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Objectives: We aimed to cardiologically evaluate the consequences of glycosaminoglycan (GAG) accumulation in the large vessels of patients with mucopolysaccharidosis (MPS)., Methods: The left ventricular wall thickness, left ventricular mass (LVmass) were evaluated and aortic annulus diameter (AA), aortic sinus valsalva diameter (SV), sinotubular junction diameter (STJ), systolic aortic diameter (ADs), diastolic aortic diameter (ADd) body indices were obtained by dividing by the surface area. Aortic distensibility and stiffness index were obtained using aortic strain. Ejection fraction, mitral E and A velocities, mitral early diastolic tissue velocity (e'), E/A ratio, and E/e' ratio were evaluated., Results: The LVED-i, LVmass-i, AA-i, SV-i, STJ-i, ADs-i, and ADd-i values were significantly higher in the MPS group. While the E and e' velocities and E/A ratio were significantly low in the MPS group, the A velocity and E/e' ratio were significantly high. While the stiffness index, SBP, and PP values were significantly higher in the MPS group, the aortic strain and distensibility were significantly lower. There was a correlation between the stiffness index and the aortic strain, distensibility, SBP, PP, and ventricular function. Cardiac function, aortic diameter, and aortic elasticity characteristics were similar between patients with MPS who received ERT and those who did not., Conclusions: In the MPS group, aortic elasticity properties were impaired, and aortic stiffness increased. ERT has positive effects on cardiac function, aortic diameter, and aortic stiffness in MPS patients. An increased LVmass-i and impaired ventricular geometric structure in patients with MPS may be associated with increased aortic stiffness., (© 2024 Walter de Gruyter GmbH, Berlin/Boston.)

Kirigami is the art of cutting paper to create three-dimensional figures for primarily aesthetic purposes. However, it can also modify the mechanical behavior of the resulting structure. In the literature, kirigami has been applied to modify the material's structural behavior, such as by changing its elasticity, rigidity, volume, or any other characteristic. This article examines the behavior of a pattern of rectangular kirigami cuts on a thermoplastic polyurethane soft material structure and its influence on the mechanical parameters of the macrostructure. The results demonstrate that rectangular kirigami patterns significantly affect the stiffness of the test specimens, changing from 1635 N/m to 4020 N/m. In elongation, there is a variation from 176.6% to 218% by simply altering the height of the rectangular cut. This enables the adjustment of the soft material structure's stiffness based on the geometry of the propagating kirigami cuts. [ABSTRACT FROM AUTHOR]

The Magazine of Concrete Research has awarded the Magazine of Concrete Research Prize to a paper published in 2022 by Lye et al. The paper discusses the importance of considering the influence of aggregate stiffness in estimating creep and shrinkage of concrete, as current design codes and models inaccurately estimate these properties. The authors propose two empirical models for estimating creep coefficient and shrinkage strain of concrete, taking into account various types of aggregates and the proportion of cement used. The paper provides valuable insights for designing structures with long-term integrity. [Extracted from the article]

In recent years, demographers have parsed variation in survivorship into two distinct components: the shape and the pace of ageing. The pace of ageing is defined by measures of longevity such as mean life expectancy or maximum longevity, whereas measures of the shape of ageing attempt to classify different shapes of the survivorship curve. We recently published a paper pointing out that a commonly used discretization of a shape measure, Keyfitz' entropy, does not correctly classify survivorship curves into negatively and positively senescing curves (de Vries et al., 2023). In that paper, we also suggested an alternative, accurate discrete‐time version of Keyfitz' entropy. de Vries et al. (2023) ended with two open questions, both of which have been answered by Giaimo (2024) now: (1) Can a discrete‐time entropy measure of survivorship be generalized beyond age‐based population models? Giaimo (2024) introduce a new formula that achieves this. (2) Will a discretization of Keyfitz' derivation of his measure as the elasticity of lifespan to a uniform change in mortality lead to the same formula as a discretization of Keyfitz' result? Giaimo (2024) answers: no.Here, we briefly discuss the implications of the results obtained by Giaimo (2024), and the implementation of his new formula into the Rpackage Rage, which is widely used for comparative demographic studies.We showcase the strength of the new method by reanalysing a comparison of Keyfitz' entropy to another shape measure. We find that the comparison is significantly altered by using Giaimo's new Keyfitz' formula.This example strengthens Giaimo's (2004) words of warning in approaching discretizations with attentiveness. [ABSTRACT FROM AUTHOR]

The paper investigates a problem concerning the equilibrium of a solid body containing a thin rigid inclusion and a crack. It is assumed that the body is hyperelastic, therefore, it is described within the framework of finite strain theory. One of the peculiarities of this problem is a global injectivity constraint, which prevents the body, the crack faces and the inclusion from both mutual and self penetration. First, the paper deals with the differential formulation of the problem. Next, we consider energy minimization, showing that the latter provides the weak formulation of the former. Finally, the existence of the weak solution is demonstrated through the use of the variational technique. This article is part of the theme issue 'Non-smooth variational problems with applications in mechanics'. [ABSTRACT FROM AUTHOR]

In this paper, we study the asymptotic behavior of transmission system for coupled Kirchhoff plates, where one equation is conserved and the other has dissipative property, and the dissipation mechanism is given by fractional damping (- Δ) 2 θ v t with θ ∈ [ 1 2 , 1 ] . By using the semigroup method and the multiplier technique, we obtain the exact polynomial decay rates, and find that the polynomial decay rate of the system is determined by the inertia/elasticity ratios and the fractional damping order. Specifically, when the inertia/elasticity ratios are not equal and θ ∈ [ 1 2 , 3 4 ] , the polynomial decay rate of the system is t - 1 / (10 - 4 θ) . When the inertia/elasticity ratios are not equal and θ ∈ [ 3 4 , 1 ] , the polynomial decay rate of the system is t - 1 / (4 + 4 θ) . When the inertia/elasticity ratios are equal, the polynomial decay rate of the system is t - 1 / (4 + 4 θ) . Furthermore it has been proven that the obtained decay rates are all optimal. The obtained results extend the results of Oquendo and Suárez (Z Angew Math Phys 70(3):88, 2019) for the case of fractional damping exponent 2 θ from [0, 1] to [1, 2]. [ABSTRACT FROM AUTHOR]

Purpose: This paper aims to present two Anand's model parameter sets for the multilayer silver–tin (AgSn) transient liquid phase (TLP) foils. Design/methodology/approach: The AgSn TLP test samples are manufactured using pre-defined optimized TLP bonding process parameters. Consequently, tensile and creep tests are conducted at various loading temperatures to generate stress–strain and creep data to accurately determine the elastic properties and two sets of Anand model creep coefficients. The resultant tensile- and creep-based constitutive models are subsequently used in extensive finite element simulations to precisely survey the mechanical response of the AgSn TLP bonds in power electronics due to different thermal loads. Findings: The response of both models is thoroughly addressed in terms of stress–strain relationships, inelastic strain energy densities and equivalent plastic strains. The simulation results revealed that the testing conditions and parameters can significantly influence the values of the fitted Anand coefficients and consequently affect the resultant FEA-computed mechanical response of the TLP bonds. Therefore, this paper suggests that extreme care has to be taken when planning experiments for the estimation of creep parameters of the AgSn TLP joints. Originality/value: In literature, there is no constitutive modeling data on the AgSn TLP bonds. [ABSTRACT FROM AUTHOR]

This paper proposes, for particle-based materials, a higher-order nonlocal elasticity continuum model that includes the Piola peridynamics and the Eringen nonlocal elasticity. When referring to particle-based materials, we denote systems that can be modeled as assemblies of material points (or particles). Note that this paper is not devoted to granular materials, then factors such as the topology of contacts, granulometry, grain sizes, shapes, and geometric structure are not considered. Additionally, when referring to Piola peridynamics, we specifically denote the particular peridynamic model developed by Piola, which differs from the commonly adopted approach to peridynamics. The proposed higher-order nonlocal elasticity continuum model offers several advantages. First, it can describe interactions between material points over longer ranges than those considered by Eringen nonlocal elasticity. Second, it exhibits similar characteristics to gradient-type theories and Piola peridynamics, enabling the consideration of more complex external and contact actions, including Nth order forces and stresses. Furthermore, the proposed deterministic model is developed to lay the foundation for a stochastic formulation applicable to uncertain particle-based materials. We want to emphasize that the aim of this paper is not to unify Eringen nonlocal elasticity with the various existing peridynamic models. [ABSTRACT FROM AUTHOR]

The paper presents an identification process of model parameters of a thin nickel-titanium alloy wire based on experimental research. The wire made of NiTi alloy was subjected to a tensile test to obtain the stress-strain characteristic. Parameters of the non-linear material model were identified based on the obtained experimental results. The material model used in the conducted research may be used for simulation of the shape memory effect and pseudoelasticity of the shape memory alloy. The generated results of numerical simulations have a good approximation with the conducted experimental tests. [ABSTRACT FROM AUTHOR]

Purpose: The main aim of the current paper is to find a numerical plan for hydraulic fracturing problem with application in extracting natural gases and oil. Design/methodology/approach: First, time discretization is accomplished via Crank-Nicolson and semi-implicit techniques. At the second step, a high-order finite element method using quadratic triangular elements is proposed to derive the spatial discretization. The efficiency and time consuming of both obtained schemes will be investigated. In addition to the popular uniform mesh refinement strategy, an adaptive mesh refinement strategy will be employed to reduce computational costs. Findings: Numerical results show a good agreement between the two schemes as well as the efficiency of the employed techniques to capture acceptable patterns of the model. In central single-crack mode, the experimental results demonstrate that maximal values of displacements in x- and y- directions are 0.1 and 0.08, respectively. They occur around both ends of the line and sides directly next to the line where pressure takes impact. Moreover, the pressure of injected fluid almost gained its initial value, i.e. 3,000 inside and close to the notch. Further, the results for non-central single-crack mode and bifurcated crack mode are depicted. In central single-crack mode and square computational area with a uniform mesh, computational times corresponding to the numerical schemes based on the high order finite element method for spatial discretization and Crank-Nicolson as well as semi-implicit techniques for temporal discretizations are 207.19s and 97.47s, respectively, with 2,048 elements, final time T = 0.2 and time step size τ = 0.01. Also, the simulations effectively illustrate a further decrease in computational time when the method is equipped with an adaptive mesh refinement strategy. The computational cost is reduced to 4.23s when the governed model is solved with the numerical scheme based on the adaptive high order finite element method and semi-implicit technique for spatial and temporal discretizations, respectively. Similarly, in other samples, the reduction of computational cost has been shown. Originality/value: This is the first time that the high-order finite element method is employed to solve the model investigated in the current paper. [ABSTRACT FROM AUTHOR]

Novel engine fan blades are made of 3D woven composite materials and incorporate a protective metallic layer at the leading edge. The end-of-life of such structures involves complicated disassembly and recycling processes. In this paper, laser-shock is being investigated as an environmentally friendly disassembly method. In this context, symmetric laser-shock experiments that have been conducted in a previous work using a time delay between the shots have been proven successful for debonding initiation and propagation as they manage to effectively focus the tensile stress field developed by the shock waves at the bondline. In this paper, a numerical model simulating the symmetric laser-shock disassembly of titanium/CFRP specimens has been developed using the LS-Dyna explicit FE code. The aim is to give a deeper insight into the physical mechanisms and to optimize the experimental process. To simulate the behavior of the titanium part, the Johnson-Cook material model in combination with Grüneisen equation of state has been employed, while for the composite part a progressive damage material model incorporating high-strain rate effects has been used. The bondline between the two parts has been modeled using cohesive zone elements. To obtain tensile and shear elastic and strength properties at high strain rates for the composite damage model, tension and punch shear Split-Hopkinson Bar tests have been conducted. The numerical results correlate well with back-face velocity profiles obtained from single sided laser shock experiments and with debonding patterns in the adhesive, observed in electron microscopy images, induced by symmetrical laser shock experiments. After the validation, the numerical model has been used successfully to simulate a larger disassembly process composed of 16 consecutive shots. [ABSTRACT FROM AUTHOR]

The term "viscoelastic pipe" refers to high polymer pipes that exhibit both elastic and viscoelastic properties. Owing to their widespread use in water transport systems, it is important to understand the transient flow characteristics of these materials for pipeline safety. Despite extensive research, these characteristics have not been sufficiently explored. This study evaluates the impact of friction models on the transient flow of viscoelastic pipes across various Reynolds numbers by employing an energy analysis approach. Given the complexity and computational demands of two-dimensional models, this paper compares the accuracy of one-dimensional and quasi-two-dimensional models. Notably, the superiority of the quasi-two-dimensional model in simulating viscoelastic pipelines is demonstrated. Owing to the interaction between pressure waves and fluid within viscoelastic pipes, fluid–structure coupling significantly attenuates pressure waves during transmission. These findings shed light on the constitutive properties of viscoelastic pipes and the influence of pipe wall friction models on transient hydraulic characteristics, building upon prior studies focused on elastic pipes. Nevertheless, numerous factors affecting transient flow in viscoelastic pipes remain unexplored. This paper suggests further analysis of strain effects, starting with temperature and pipe dynamics, to enhance the understanding of the coupling laws and flow mechanisms in viscoelastic pipelines. [ABSTRACT FROM AUTHOR]

Recently, composite PVDF membranes with good performance have triggered enormous interest because of their great potential application. However, the uncertainty of mechanical properties limits their application. Herein, this paper reveals the elastic modulus properties of the loading angle between warp and tensile direction using the uni-axial tensile test of SH-1050P membrane textile. In addition, the bi-axial tensile test with different loading ratios was implemented. Both uni-axial and bi-axial ductile load-displacement/stress-strain curves are featured. It is the first to establish a relationship between the elastic modulus and the loading angle using a theoretical method based on the assumption that there is no slippage and crease between yarns and matric. Furthermore, simulations with different textile parameters were carried out to verify the theoretical results. The key finding is that the elastic modulus under uni-axial load can be divided into two stages, which are elasticity and plasticity. Both of which are proportional to the sine function applied to two times the loading angle. The Poisson's ratio of SH-1050P textile can be considered as a fixed value of 0.11. This conclusion can be extended to similar textiles. The outcome of this paper contributes to a deeper understanding of the PVDF memrane's mechanical behavior and presents a novel insight into its response to different loading conditions. [ABSTRACT FROM AUTHOR]

This paper investigates ESG from the perspective of changes in input elasticities of substitution and complementarity. Rather than compute these elasticities from the cost function, we compute them from the Input Distance Function (IDF). Our data are from Refinitiv Eikon Datastream database. We focus on the US economy due to her global role in the world economy and hence spillover effects of uncertainties on the rest of the world. The data consist of 5,798 companies comprising 38 US industries that span for 12 years from 2009 to 2020 and include: (i) financial data on sales, capital and employees; (ii) two financial ratios and (iii) three main ESG indicators. We compute Antonelli Elasticity of Complementarity (AEC) and Allen-Uzawa Elasticity of Substitution (AES) from the translog of IDF function. We find that the standard inputs have positive AEC elasticities; however, ESG cross-elasticities exhibit negative signs, classifying them as q-substitutes. Therefore, an increase in one of the ESG values leads to a decrease in the marginal value of the other. On the other hand, AES elasticities have a negative sign only for the Governance-Environment "doublet'; the rest of the pairs are positive implying that they are p-complements. [ABSTRACT FROM AUTHOR]

In this paper, we investigate various stabilisation problems of a hybrid system of elasticity, consisting of a thin tape, which moves axially between two sets of rollers. We present a control solution, which works simultaneously, for three variants of the tape model. In particular, we design boundary feedback control laws via Lyapunov's second method. The resulting closed-loop system for the general case is then analysed, where we prove the existence and uniqueness of solution using the semigroup theory of linear operators; furthermore, we prove the exponential decay of the solution via a frequency domain theorem. The stabilisation of the two other special cases is derived implicitly from the general case proofs presented in the paper. Finally, the paper is concluded by presenting computer simulations to support the theoretical results. [ABSTRACT FROM AUTHOR]

Optimizing the regeneration process of surgically created anastomoses (blood vessels, intestines, nerves) is an important topic in surgical research. One of the most interesting parameter groups is related to the biomechanical properties of the anastomoses. Depending on the regeneration process and its influencing factors, tensile strength and other biomechanical features may change during the healing process. Related to the optimal specimen size, the range and accuracy of measurements, and applicability, we have developed a custom-tailored microcontroller-based device. In this paper, we describe the hardware and software configuration of the latest version of the device, including experiences and comparative measurements of tensile strength and elasticity of artificial materials and biopreparate tissue samples. The machine we developed was made up of easily obtainable parts and can be easily reproduced on a low budget. The basic device can apply a force of up to 40 newtons, and can grasp a 0.05-1 cm wide, 0.05-1 cm thick tissue. The length of the test piece on the rail should be between 0.3 and 5 cm. Low production cost, ease of use, and detailed data recording make it a useful tool for experimental surgical research.

Age-related cataract is the most frequent cause of blindness in the world being responsible for 48% of blindness and affecting more than 10% of the working population. Currently there is no objective data of the lens biomechanical properties so the process by which the cataract affects the lens's properties (e.g. hardness and elasticity) is still unclear. A modified animal model was produced to create different severities of nuclear cataract. Different doses of sodium selenite were injected in two different moments of the rat' eyes maturation resulting in 12, 13 and 11 rats with incipient, moderate and severe cataract, respectively. The nucleus and cortex's hardness and the stiffness were measured using NanoTest™. Statistically significant differences were found between healthy and cataractous lenses. Statistically significant differences were also found between the different nuclear cataract degrees (p = 0.016), showing that the lens' hardness increases with cataract formation. The nucleus shows a higher hardness increase with cataract formation (p = 0.049). The animal model used in this study allowed for the first time the characterization of the lens's hardness and elasticity in two regions of the lens, in healthy and cataractous lenses., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Miguel Caixinha reports financial support was provided by Foundation for Science and Technology. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Cell polarization can be guided by substrate topology through space constraints and adhesion induction, which are part of cellular mechanosensing pathways. Here, we demonstrated that protein tyrosine phosphatase Shp2 plays a crucial role in mediating the response of cells to substrate spatial cues. When compared to cells spreading on surfaces coated uniformly with fibronectin (FN), cells attached to 10 μm-width FN-strip micropattern (MP), which provides spatial cues for uniaxial spreading, exhibited elongated focal adhesions (FAs) and aligned stress fibers in the direction of the MP. As a result of uniaxial cell spreading, nuclei became elongated, dependent on ROCK-mediated actomyosin contractility. Additionally, intracellular viscoelasticity also increased. Shp2-deficient cells did not display elongated FAs mediated by MP, well-aligned stress fibers, or changes in nuclear shape and intracellular viscoelasticity. Overall, our data suggest that Shp2 is involved in regulating FAs and the actin cytoskeleton to modulate nuclear shape and intracellular physical properties in response to substrate spatial cues., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

In situ forming poly(dimethylaminoethyl methacrylate-co-glycidylmethacrylate)/Chitosan, P(DMAEMA-co-GMA)/Chitosan, (PDG/CS) cryobeads based on "dropwise freezing into cryogenic liquid method" combined with "blending with polymer method" are promising for applications due to their pH-responsiveness and stability under physiological conditions. Based on classical contact mechanics, Hertzian elasticity of semi-interpenetrated network (semi-IPN) cryobeads was analyzed to examine whether there is a direct correlation between elastic properties of single particle and its macroscopic behavior. A one-step procedure has been proposed to design chitosan-interpenetrated cryobeads with a cationic nature via combination of structural properties as well as functionality of chitosan containing primary and secondary hydroxyl and amino groups. The study is focused on characterization of network formation kinetics in different shapes and how different production variables affect the elasticity/swelling performance of cross-linked system. The elastic properties of semi-IPN cryobeads were improved by both adding chitosan to copolymer PDG structure and lowering the gelation temperature to cryogelation conditions. The results obtained highlighted the importance of composition to modulate elasticity, the influence of preparation temperature and shape of cryobeads on their elasticity. Findings regarding the topography-dependent local elastic properties of chitosan-incorporated semi-IPN gels offer possibilities for modulating the behavior of chitosan-based soft materials., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

The equine hoof wall has outstanding impact resistance, which enables high-velocity gallop over hard terrain with minimum damage. To better understand its viscoelastic behavior, complex moduli were determined using two complementary techniques: conventional (∼5 mm length scale) and nano (∼1 µm length scale) dynamic mechanical analysis (DMA). The evolution of their magnitudes was measured for two hydration conditions: fully hydrated and ambient. The storage modulus of the ambient hoof wall was approximately 400 MPa in macro-scale experiments, decreasing to ∼250 MPa with hydration. In contrast, the loss tangent decreased for both hydrated (∼0.1-0.07) and ambient (∼0.04-0.01) conditions, over the frequency range of 1-10 Hz. Nano-DMA indentation tests conducted up to 200 Hz showed little frequency dependence beyond 10 Hz. The loss tangent of tubular regions showed more hydration sensitivity than in intertubular regions, but no significant difference in storage modulus was observed. Loss tangent and effective stiffness were higher in indentations for both hydration levels. This behavior is attributed to the hoof wall's hierarchical structure, which has porosity, functionally graded aspects, and material interfaces that are not captured at the scale of indentation. The hoof wall's viscoelasticity characterized in this work has implications for the design of bioinspired impact-resistant materials and structures. STATEMENT OF SIGNIFICANCE: The outer wall of horse hooves evolved to withstand heavy impacts during gallop. While previous studies have measured the properties of the hoof wall in slowly changing conditions, we wanted to quantify its behavior using experiments that replicate the quickly changing forces of impact. Since the hoof wall's structure is complex and contributes to its overall performance, smaller scale experiments were also performed. The behavior of the hoof wall was within the range of other biological materials and polymers. When hydrated, it becomes softer and can dissipate more energy. This work improves our understanding of the hoof's function and allows for more accurate simulations that can account for different impact speeds., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

The paper is concerned with the boundary conditions of explicit gradient elasticity of Mindlin's type in dynamics. It has been argued in an earlier paper that acceleration terms should not be present in the boundary tractions because of objectivity arguments. This is discussed in the present paper in more detail, and it is supplemented by assuming the validity of the principle of material frame indifference. Furthermore, new examples are discussed in order to illustrate that significant differences exist in the responses predicted by boundary tractions with and without acceleration terms. [ABSTRACT FROM AUTHOR]

This paper deals with an innovative nondestructive technique for composites (local-IET), which is based on the Impulse Excitation Technique (IET) and, in the presence of damage, assesses the degradation of the elastic properties of a local region of the laminate by reversibly clamping its boundaries. In this paper, a numerical analysis of the sensitivity of the local-IET to the delamination damage mechanism is conducted. Firstly, a Finite Element (FE) model of the local-IET test is determined through experimental investigations on undamaged composite laminates, which cover a wide range and are made of glass or carbon fibers, through resin infusion or pre-preg consolidation and with unidirectional or fabric textures. The vibrational response of a glass fiber composite with local delamination is then assessed with the local-IET. By modeling the delamination in the simulation environment, the effectiveness of the FE model in replicating the vibrational response, even in the presence of delamination, is shown through a comparison with the experimental results. Finally, the FE model is exploited to perform a sensitivity analysis, showing that the technique is able to detect the presence of delamination. [ABSTRACT FROM AUTHOR]

The paper contains a parametric dynamic analysis of cable-strut domes. The special structures named tensegrity are considered. Two qualitative different tensegrity domes, i.e., the Geiger dome and the Levy dome are taken into account. The aim of the study is to compare the dynamic behaviour of such structures. The first stage of analysis involves the identification of initial prestress forces (system of internal forces, which holds structural components in stable equilibrium) and infinitesimal mechanisms. The second stage focuses on calculating natural frequencies, while in the last, the impact of time-independent external loads on vibrations is studied. The influence of initial prestress and external load on the dynamic response of the structures is considered. A geometrically non-linear model is used to analysis. Presented considerations are crucial for the next step in the analysis, i.e., dynamic stability analysis of the behaviour of tensegrity structures under periodic loads. [ABSTRACT FROM AUTHOR]

In this paper, we have synthesised cholesteryl 4-allyloxybenzoate (MB), crosslinking agent dodecane-1,12-diyl bis(undec-10-enoate) (MG), and A'BGF series liquid crystalline elastomer (LCE) films which take polymethylhydrosiloxane (A') as the backbone, MB as the cholesteric liquid crystal (LC) monomer, and MG and bis-vinyl silicone oil (MF) with different reactivities as cross-linking agent for exploring the effect of the change of MF content on the properties of the elastomeric films. The experimental results show that the synthesised MB, MG, and the LCE films are all consistent with the molecular design; MB is an enantiotropic cholesteric LC. The synthesised LCE films are cholesteric LCs, have certain selective reflection characteristic, higher thermal stability, and their Tg decreased down to 3.9°C as MF increasing. During the heating and cooling, the liquid crystalline properties of the LCE films have a good reversibility. Among the synthesised LCE films, A'BGF-2 has stretching radio of 264.8% at room temperature, with the best elastic properties. By adjusting the ratio of MF, the content of small-molecule MB remained in the films can be changed, which will affect the optical properties and elasticity of the LCE films. The experiments provide a method for the preparation of highly elastic side chain LCE film. [ABSTRACT FROM AUTHOR]

In this paper we consider the problem of minimizing functionals of the form E (u) = ∫ B f (x , ∇ u) d x in a suitably prepared class of incompressible, planar maps u : B → R 2 . Here, B is the unit disk and f (x , ξ) is quadratic and convex in ξ . It is shown that if u is a stationary point of E in a sense that is made clear in the paper, then u is a unique global minimizer of E(u) provided the gradient of the corresponding pressure satisfies a suitable smallness condition. We apply this result to construct a non-autonomous, uniformly convex functional f (x , ξ) , depending smoothly on ξ but discontinuously on x, whose unique global minimizer is the so-called N - covering map, which is Lipschitz but not C 1 . [ABSTRACT FROM AUTHOR]

The literature about the asymptotic numerical method (ANM) is reviewed in this paper as well as its application to hyperelasticity and elastoplasticity. ANM is a generic continuation method based on the computation of Taylor series for solving nonlinear partial differential equations. Modern techniques of high-order differentiation provide simple tools for computing these power series, the corresponding algorithms for finite strain elasticity and elastoplasticity being summarized here. Taylor series is not only a computation tool, but it contains also useful information about the structure of the considered solution curve. The paper ends with a short historical account about the development of this numerical method. [ABSTRACT FROM AUTHOR]

By considering the joint effects of the KelvineHelmholtz (KH) and RayleigheTaylor (RT) instabilities, this paper presents an interpretation of the wavy patterns that occur in explosive welding. It is assumed that the elasticity of the material at the interface effectively determines the wavelength, because explosive welding is basically a solid-state welding process. To this end, an analytical model of elastic hydrodynamic instabilities is proposed, and the most unstable mode is selected in the solid phase. Similar approaches have been widely used to study the interfacial behavior of solid metals in high-energy-density physics. By comparing the experimental and theoretical results, it is concluded that thermal softening, which significantly reduces the shear modulus, is necessary and sufficient for successful welding. The thermal softening is verified by theoretical analysis of the increase in temperature due to the impacting and sliding of the flyer and base plates, and some experimental observations are qualitatively validated. In summary, the combined effect of the KH and RT instabilities in solids determines the wavy morphology, and our theoretical results are in good qualitative agreement with experimental and numerical observations. [ABSTRACT FROM AUTHOR]

Polyamide 12 (PA12) is vastly utilized in many additive manufacturing methods, such as Selective Laser Sintering (SLS), and a better understanding of its mechanical behaviors promotes available knowledge on the behaviors of 3D-printed parts made from this polymer. In this paper, SLS-produced standard tensile specimens are studied under monotonic and cyclic tension tests, as well as stress relaxation experiments, and the obtained force-displacement responses are shown to be consistent with a hyper-viscoelastic material model. This finding is also observed in typical pantographic structures produced by the same manufacturing parameters. To propose a constitutive model for predicting these behaviors, the convolution integral of a strain-dependent function and a time-dependent function is developed where the material parameters are determined with the use of both short-term and long-term responses of the specimens. Numerical results of the presented model for standard test specimens are shown to be in good agreements with the experimental ones under various loading conditions. To prove the capabilities of the proposed model in studying any SLS-produced part, finite element implementation of the constitutive equations is shown to provide numerical results in agreement with the empirical findings for tensile loading of the 3D-printed pantographic structure., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 Kadkhodaei et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Elastic carbon aerogels have promising applications in the field of wearable sensors. Herein, a new strategy for preparing carbon aerogels with excellent compressive strength and strain, shape recovery, and fatigue resistance was proposed based on the structure design and carbonization optimization of nanocellulose-based precursor aerogels. By the combination of directional freezing and zinc ion cross-linking, bacterial cellulose (BC)/alginate (SA) composite aerogels with high elasticity and compressive strength were first achieved. The existance of zinc ions also significantly improved the carbon retention rate and inhibited structural shrinkage, thus making the carbon aerogels retain ultra-high elasticity and fatigue resistance after compression. Moreover, the carbon aerogel possessed excellent piezoresistive pressure sensing performance with a wide detection range of 0-7.8 kPa, high sensitivity of 11.04 kpa -1 , low detection limit (2 % strain), fast response (112 ms), and good durability (over 1,000 cycles). Based on these excellent properties, the carbon aerogel pressure sensors were further successfully used for human motion monitoring, from joint motion to and speech recognition., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Living organisms form complex mineralized composite architectures that perform a variety of essential functions. These materials are commonly utilized for load-bearing purposes such as structural stability and mechanical strength in combination with high toughness and deformability, which are well demonstrated in various highly mineralized molluscan shell ultrastructures. Here, the mineral components provide the general stiffness to the composites, and the organic interfaces play a key role in providing these biogenic architectures with mechanical superiority. Although numerous studies employed state-of-the-art methods to measure and/or model and/or simulate the mechanical behavior of molluscan shells, our understanding of their performance is limited. This is partially due to the lack of the most fundamental knowledge of their mechanical characteristics, particularly, the anisotropic elastic properties of the mineral components and of the tissues they form. In fact, elastic constants of biogenic calcium carbonate, one of the most common biominerals in nature, is unknown for any organism. In this work, we employ the ultrasonic pulse-echo method to report the elasticity tensor of two common ultrastructural motifs in molluscan shells: the prismatic and the nacreous architectures made of biogenic calcite and aragonite, respectively. The outcome of this research not only provides information necessary for fundamental understanding of biological materials formation and performance, but also yields textbook knowledge on biogenic calcium carbonate required for future structural/crystallographic, theoretical and computational studies., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Igor Zlotnikov reports financial support was provided by TU Dresden. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

A full understanding of the material properties of skin tissue is crucial for exploring its tribo-mechanical behaviour. It has been widely accepted that the mechanical behaviour of skin tissue for both small and large deformations can be accurately described using a hyperelastic model, such as the one developed by Ogden. However, obtaining these Ogden parameters for in-vivo skin by in-vivo experiments no matter the indentation or suction tests is a significant challenge. The mathematical model used to describe the material behaviour during the test should consider not only the material nonlinearity but also the geometrical confinement of the tissue, the large deformations induced, and the fact that the specimens are relatively thin. A range of contact models is available to describe the contact behaviour during the indentation test. However, none of them can be used for hyperelastic materials with small thickness under large deformations. Simultaneously explaining material nonlinearity and geometric nonlinearity, either through theoretical equations or numerical calculations, poses a significant challenge. In this research, we propose a pragmatic method to obtain Ogden parameters for in-vivo skin tissue by combining experimental indentation results and numerical simulations. The indentation tests were used to obtain the force-indentation depth curves, while the numerical simulations were used to obtain the strain fields. The method assumes the material behaviour of specimens can be linearized in each small deformation increment, and the contact model developed by Hayes can be applied to accommodate each increment. Then, the linear elastic behaviour in each increment can be described by the elastic modulus E which were obtained using Hayes model, and the principal stresses in each increment were subsequently obtained using Hooke's law. By combining all stress fields, overall stress-strain curves can be constructed, from which the hyperelastic Ogden parameters can be obtained. A second numerical simulation of the hyperelastic indentation was then performed using the obtained Ogden parameters, allowing a comparison of the experimental and simulated relationships between force and indentation., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Magnetic resonance elastography (MRE) and diffusion-weighted imaging (DWI) are complementary imaging techniques that detect disease based on viscoelasticity and water mobility, respectively. However, the relationship between viscoelasticity and water diffusion is still poorly understood, hindering the clinical translation of combined DWI-MRE markers. We used DWI-MRE to study 129 biomaterial samples including native and cross-linked collagen, glycosaminoglycans (GAGs) with different sulfation levels, and decellularized specimens of pancreas and liver, all with different proportions of solid tissue, or solid fractions. We developed a theoretical framework of the relationship between mechanical loss and tissue-water mobility based on two parameters, solid and fluid viscosity. These parameters revealed distinct DWI-MRE property clusters characterizing weak, moderate, and strong water-network interactions. Sparse networks interacting weakly with water, such as collagen or diluted decellularized tissue, resulted in marginal changes in water diffusion over increasing solid viscosity. In contrast, dense networks with larger solid fractions exhibited both free and hindered water diffusion depending on the polarity of the solid components. For example, polar and highly sulfated GAGs as well as native soft tissues hindered water diffusion despite relatively low solid viscosity. Our results suggest that two fundamental properties of tissue networks, solid fraction and network polarity, critically influence solid and fluid viscosity in biological tissues. Since clinical DWI and MRE are sensitive to these viscosity parameters, the framework we present here can be used to detect tissue remodeling and architectural changes in the setting of diagnostic imaging. STATEMENT OF SIGNIFICANCE: The viscoelastic properties of biological tissues provide a wealth of information on the vital state of cells and host matrix. Combined measurement of viscoelasticity and water diffusion by medical imaging is sensitive to tissue microarchitecture. However, the relationship between viscoelasticity and water diffusion is still poorly understood, hindering full exploitation of these properties as a combined clinical biomarker. Therefore, we analyzed the parameter space accessible by diffusion-weighted imaging (DWI) and magnetic resonance elastography (MRE) and developed a theoretical framework for the relationship between water mobility and mechanical parameters in biomaterials. Our theory of solid material properties related to particle motion can be translated to clinical radiology using clinically established MRE and DWI., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

The mechanical attributes of soft tissues within the gastrointestinal (GI) tract are crucial for the effective operation of the GI system, and alterations in these properties may play a role in motility-related disorders. Various constitutive modeling approaches have been suggested to comprehend the response of soft tissues to diverse loading conditions. Among these, hyperelastic constitutive models based on finite elasticity have gained popularity. However, these models fall short in capturing rate- and time-dependent tissue properties. In contrast, finite viscoelastic models offer a solution to overcome these limitations. Nevertheless, the development of a suitable finite viscoelastic model, coupled with a variational formulation for efficient finite element (FE) implementation, remains an ongoing challenge. This study aims to address this gap by developing diverse finite viscoelastic constitutive relations and applying them to characterize soft tissue. Furthermore, the research explores the creation of compressible, nearly incompressible, and incompressible versions of viscoelastic constitutive relations, along with their variational formulation, to facilitate efficient FE implementation. The proposed model demonstrates remarkable accuracy in replicating experimental results, achieving an R 2 value exceeding 0.99., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Mechanical properties are becoming fundamental for advancing the comprehension of cellular processes. This study addresses the relationship between viscoelastic properties and the cellular mineralization process. Osteoblast-like cells treated with an osteogenic medium were employed for this purpose. Additionally, the study explores the impact of hydroxyapatite (HA) and hydroxyapatite/silver (HA/Ag) composite on this process. AFM relaxation experiments were conducted to extract viscoelastic parameters using the Fractional Zener (FZ) and Fractional Kelvin (FK) models. Our findings revealed that the main phases of mineralization are associated with alterations in the viscoelastic properties of osteoblast-like cells. Furthermore, HA and HA/Ag treatments significantly influenced changes in the viscoelastic properties of these cells. In particular, the HA/Ag treatment demonstrated a marked enhancement in cell fluidity, suggesting a possible role of silver in accelerating the mineralization process. Moreover, the study underscores the independence observed between fluidity and stiffness, indicating that modifications in one parameter may not necessarily correspond to changes in the other. These findings shed light on the factors involved in the cellular mineralization process and emphasize the importance of using viscoelastic properties to discern the impact of treatments on cells., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

This study presents a comprehensive analysis of hyperelastic thin cylindrical shells exhibiting initial geometrical imperfections. The nonlinear equations of motion are derived using an improved formulation of Donnell's nonlinear shallow-shell theory and Lagrange's equations, incorporating the small strain hypothesis. Mooney-Rivlin constitutive model is employed to capture the hyperelastic behavior of the material. The coupled nonlinear equations of motion are analytically solved using Multiple-Scale method, which effectively accounts for the inherent nonlinearity of the system. To ensure the model's accuracy, the linear model is verified by comparing the results with those obtained through hybrid finite element method. Subsequently, the model with only geometrical nonlinearity is evaluated against other research works existing in the open literature to ensure its reliability and precision. Finally, the results of the model, considering both geometrical and physical nonlinearity, are verified against the results obtained from Abaqus software. The main objective of this research is to provide a detailed understanding of the response of hyperelastic thin cylindrical shells in the presence of initial geometric imperfections. In this order, the impact of three distinct geometric imperfections - axisymmetric, asymmetric, and a combination of driven and companion modes - on the natural frequency is examined. The behavior of each of these geometric imperfections is investigated by varying their respective coefficients. The numerical results indicate that geometric imperfections enhance the natural frequency, and employing different models for imperfections leads to a variation in this trend. In the amplitude response of hyperelastic cylindrical shells, two peaks coexist, reflecting the softening and hardening responses of the system. Distinct initial geometric imperfections influence these two peaks., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

In the field of virtual surgery and deformation simulation, the identification of elastic parameters of human soft tissues is a critical technology that directly affects the accuracy of deformation simulation. Current research on soft tissue deformation simulation predominantly assumes that the elasticity of tissues is fixed and already known, leading to the difficulty in populating with the elasticity measured or identified from specific tissues of real patients. Existing elasticity modeling efforts struggle to be implemented on irregularly structured soft tissues, failing to adapt to clinical surgical practices. Therefore, this paper proposes a new method for identifying human soft tissue elastic parameters based on the finite element method and the deep neural network, UNet. This method requires only the full-field displacement data of soft tissues under external loads to predict their elastic distribution. The performance and validity of the algorithm are assessed using test data and clinical data from rhinoplasty surgeries. Experiments demonstrate that the method proposed in this paper can achieve an accuracy of over 99% in predicting elastic parameters. Clinical data validation shows that the predicted elastic distribution can reduce the error in finite element deformation simulations by more than 80% at the maximum compared to the error with traditional uniform elastic parameters, effectively enhancing the computational accuracy in virtual surgery simulations and soft tissue deformation modeling., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Biological tissues decay over time after harvesting, which alters their biomechanical properties. This poses logistical challenges for studies investigating passive arterial biomechanics as tissues need to be characterized shortly after excision. Freezing and cryopreservation methods can help alleviate the need for biomechanical testing of fresh tissue in human ex vivo studies. However, these methods tend to eliminate or reduce arterial cell functionality and affect passive biomechanics. Furthermore, their impact on dynamic arterial biomechanics remains unknown despite arterial viscoelastic properties being an integral component contributing to arterial stiffness under in vivo loading conditions. The present study aims to investigate the impact of rapid cooling and subsequent storage at -80 °C on the passive viscoelastic properties of arterial tissue and aid in ascertaining whether this is a suitable method to delay tissue analysis for studies investigating passive arterial biomechanics. Control and frozen abdominal rat aorta segments were quasi-statically and dynamically tested using a biaxial testing set-up. The results were modeled using a constituent-based quasi-linear viscoelastic modeling framework, yielding directional stiffness parameters, individual constituent biomechanical contributions, and a quantification of viscoelastic stiffening under dynamic pressurization conditions. Frozen samples displayed significantly decreased wall thickness, viscoelastic dissipation, viscoelastic stiffening, and significantly decreased circumferential deformation with changes in luminal pressure. Furthermore, frozen samples displayed significantly increased circumferential stiffness, pulse wave velocity, and collagen load bearing. Consequently, these changes should be considered when utilizing this tissue preservation method to delay biomechanical characterization of rat aortic tissue., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Wireless modules that provide telecommunications and power-harvesting capabilities enabled by radio-frequency (RF) electronics are vital components of skin-interfaced stretchable electronics 1-7 . However, recent studies on stretchable RF components have demonstrated that substantial changes in electrical properties, such as a shift in the antenna resonance frequency, occur even under relatively low elastic strains 8-15 . Such changes lead directly to greatly reduced wireless signal strength or power-transfer efficiency in stretchable systems, particularly in physically dynamic environments such as the surface of the skin. Here we present strain-invariant stretchable RF electronics capable of completely maintaining the original RF properties under various elastic strains using a 'dielectro-elastic' material as the substrate. Dielectro-elastic materials have physically tunable dielectric properties that effectively avert frequency shifts arising in interfacing RF electronics. Compared with conventional stretchable substrate materials, our material has superior electrical, mechanical and thermal properties that are suitable for high-performance stretchable RF electronics. In this paper, we describe the materials, fabrication and design strategies that serve as the foundation for enabling the strain-invariant behaviour of key RF components based on experimental and computational studies. Finally, we present a set of skin-interfaced wireless healthcare monitors based on strain-invariant stretchable RF electronics with a wireless operational distance of up to 30 m under strain., (© 2024. The Author(s), under exclusive licence to Springer Nature Limited.)

The effects of various hydrocolloids (guar gum, xanthan gum, and carboxymethyl cellulose) on the texture, rheology, and microstructural properties of modeling clay prepared with cassava starch were investigated. Notably, incorporation of 3 % guar gum and 4 % xanthan gum into starch-based modeling clay resulted in enhancements of 94.12 % and 77.47 % in cohesiveness, and 64.70 % and 66.20 % in extensibility, respectively. For starch-based modeling clay with added guar gum and xanthan gum, compared to formulations without hydrocolloids, the linear viscoelastic range exceeded 0.04 %, and the frequency dependence of both maximum creep compliance (Jmax) and storage modulus (G') was significantly reduced. This indicates a more stable network structure and enhanced resistance to deformation. Results from Fourier Transform Infrared (FTIR) spectroscopy and X-ray diffraction (XRD) confirmed that the physical interactions between starch and various hydrocolloids, along with the addition of these hydrocolloids, inhibited the degradation effect of thermomechanical processing on the crystalline structure of starch. With the addition of guar gum, it is observed that a continuous and dense network structure forms within the starch-based modeling clay, and starch particles are distributed uniformly. In conclusion, hydrocolloids enhances the properties of starch-based modeling clay, introducing an innovative solution to the modeling clay sector., Competing Interests: Declaration of competing interest The authors declare that they have no commercial or associative interests that have appeared to inappropriately influence this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

During physiological and pathological processes, cells experience significant morphological alterations with the re-arrangement of cytoskeletal filaments, resulting in anisotropic viscoelasticity. Here, a structure-based cell model is proposed to study the anisotropic viscoelastic mechanical behaviors of living cells. We investigate how cell shape affects its creep responses in longitudinal and perpendicular directions. It is shown that cells exhibit power-law rheological behavior in both longitudinal and perpendicular directions under step stress, with a more solid-like behavior along the longitudinal direction. We reveal that the cell volume and cytoskeletal filament orientation, which have been neglected in most existing models, play a critical role in regulating cellular anisotropic viscoelasticity. The stiffness of the cell in both directions increases linearly with increasing its aspect ratio, due to the decrease of cell volume. Moreover, the increase in the cell's aspect ratio produces the aggregation of cytoskeletal filaments along the longitudinal direction, resulting in higher stiffness in this direction. It is also shown that the increase in cell's aspect ratio corresponds to a process of cellular ordering, which can be quantitatively characterized by the orientational entropy of cytoskeletal filaments. In addition, we present a simple yet robust method to establish the relationship between cell's aspect ratio and cell volume, thus providing a theoretical framework to capture the anisotropic viscoelastic behavior of cells. This study suggests that the structure-based cell models may be further developed to investigate cellular rheological responses to external mechanical stimuli and may be extended to the tissue scale. STATEMENT OF SIGNIFICANCE: The viscoelastic behaviors of cells hold significant importance in comprehending the roles of mechanical forces in embryo development, invasion, and metastasis of cancer cells. Here, a structure-based cell model is proposed to study the anisotropic viscoelastic mechanical behaviors of living cells. Our study highlights the crucial role of previously neglected factors, such as cell volume and cytoskeletal filament orientation, in regulating cellular anisotropic viscoelasticity. We further propose an orientational entropy of cytoskeletal filaments to quantitatively characterize the ordering process of cells with increasing aspect ratios. Moreover, we derived the analytical interrelationships between cell aspect ratio, cell stiffness, cell volume, and cytoskeletal fiber orientation. This study provides a theoretical framework to describe the anisotropic viscoelastic mechanical behavior of cells., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.)

In order to break the limitation that only three ideal outer boundaries (infinity, constant pressure and closed) are considered in the traditional reservoir model, the paper introduces elasticity into the outer boundary condition, and establishes a nonlinear spherical seepage model for fractal composite reservoir that considers the quadratic pressure gradient, wellbore storage, skin factor and effective radius under the elastic outer boundary condition. The dimensionless bottom-hole pressure in real space is obtained by the process of variable substitution, similar construction method and numerical inversion, while the characteristic curves are plotted to analyze the influence laws of main parameters and elasticity. The results show that the ideal outer boundary conditions previously studied are only special cases of the elastic outer boundary conditions. Furthermore, the elastic outer boundary expands the scope of data interpretation, and makes the model more general. Meanwhile, it can be seen that the similar construction method is simpler and more effective than the traditional methods for solving nonlinear models. In addition, it is further demonstrated that neglecting the quadratic pressure gradient can cause large errors. This study not only provides a new idea for well testing analysis of reservoirs but also for solving more complex seepage models. [ABSTRACT FROM AUTHOR]

Convex hull computation is a critical problem in computational geometry with a wide range of applications. Existing approaches focus on separate algorithms for calculating the convex hull of polygons and curvilinear polygons, leaving room for improvement in terms of efficiency and accuracy. To address these limitations, we propose the "Simulation of Progressively Supporting Elastic lines" (SPSEL) algorithm, which leverages the physical properties of elastic lines and their progressive support process. The SPSEL algorithm efficiently computes the convex hull of generic polygons that contain both straight and curved edges. This paper provides a comprehensive overview of the SPSEL algorithm, including its terminology, overall process, and specific methods used in key algorithmic steps. Comparative tests are conducted to assess its performance, and the experimental results demonstrate the superior performance of the SPSEL algorithm compared to the Johnstone's algorithm, specifically designed for curved convex hulls. The SPSEL algorithm exhibits efficiency and effectiveness in handling various types of generic polygons, showcasing its potential for achieving linear-time operations. Furthermore, the paper discusses the possibilities of extending the SPSEL algorithm to address the computation of convex envelopes for 3D shapes, a challenging research area with theoretical and practical implications. Overall, the SPSEL algorithm offers an advanced solution for computing convex hulls of polygons with both straight and curved edges, demonstrating improved efficiency and accuracy compared to existing methods. These findings contribute to the field of computational geometry and have broad implications for applications requiring convex hull computation in diverse domains. [ABSTRACT FROM AUTHOR]

For a given material, controllable deformations are those deformations that can be maintained in the absence of body forces and by applying only boundary tractions. For a given class of materials, universal deformations are those deformations that are controllable for any material within the class. In this paper, we characterize the universal deformations in compressible isotropic implicit elasticity defined by solids whose constitutive equations, in terms of the Cauchy stress σ and the left Cauchy-Green strain b , have the implicit form f (σ , b) = 0 . We prove that universal deformations are homogeneous. However, an important observation is that, unlike Cauchy (and Green) elasticity, not every homogeneous deformation is constitutively admissible for a given implicit-elastic solid. In other words, the set of universal deformations is material-dependent, yet it remains a subset of homogeneous deformations. [ABSTRACT FROM AUTHOR]

This paper reports the systematic study on the structure, magnetic properties and magnetoelastic properties for the Fe100− x Ga x (001) thin films epitaxially grown on the different substrates of GaAs(001) and MgO(001) using the sputtering technique. The alloy composition dependence of effective magnetoelastic coupling coefficient B eff along the FeGa [110] direction indicated that the largest magnetoelastic coupling was obtained for the Fe–Ga layer with x = 30 grown on the MgO substrate, which was evaluated to be B eff = − 9.4 × 107 erg cm−3. Considering the results of structural analysis and magnetization measurement, the different crystallite sizes depending on the kind of substrate may give rise to the different magnetoelastic coupling strengths between the Fe–Ga layers on the MgO and the GaAs. The magnetostriction along the Fe–Ga [111] direction λ 111 was also estimated with the assumption of plausible elastic property of Fe–Ga, and showed the values comparable to the reported value of bulk Fe–Ga. This means the large magnetostriction can be obtained even for the Fe–Ga thin films epitaxially grown not only on the GaAs(001) but also on the MgO(001). The findings in this work will give a guideline for designing spintronic applications with a Fe–Ga layer exhibiting a large magnetoelastic coupling. [ABSTRACT FROM AUTHOR]

The physically based deformable curve models are widely used to simulate thin one-dimensional objects in computer graphics, interactive simulation, and surgery simulation. These models consider objects to be rods described by an adapted frame curve that contains the rod's centerline as well as the orthonormal material frame of each point on the centerline. However, they pose challenges including fine discretization, redundancy in modeling slender rods, and maintaining accuracy and stability. In this paper, we propose a novel physically based deformable B-spline curve model that regards curves as rods consisting of parallel fibers and derive elastic potential energy only from curves' representations. Therefore, our model does not take rotation-based adapted frames into consideration and reduces degree of freedom. Our model divides the curves into infinitesimal elements in parameter space and derives the analytical relationship between elastic potential energy function and curves' representations through the change of total length of infinitesimal elements' fibers. Our model can support material attributes in the real world and maintain the reality and stability of the solution. We employ isogeometric analysis to solve the dynamic equations derived from our deformable model as isogeometric analysis is suitable to solve the dynamic equations of parametric models. We compare the scenarios in the real world, our model's simulation results, and other model's results to demonstrate the reality of our models. The results are in line with expectation. We design several examples to demonstrate our models' applications. [ABSTRACT FROM AUTHOR]

The paper addresses the problem of finding the necessary and sufficient conditions to be satisfied by the engineering moduli of an anisotropic material for the elastic energy to be positive for each state of strain or stress. The problem is solved first in the most general case of a triclinic material and then each possible case of elastic syngony is treated as a special case. The method of analysis is based upon a rather forgotten theorem of linear algebra and, in the most general case, the calculations, too much involved, are carried out using a formal computation code. New, specific bounds, concerning some of the technical constants, are also found. [ABSTRACT FROM AUTHOR]

As the size of a layered structure scales down, the adhesive layer thickness correspondingly decreases from macro- to micro-scale. The influence of the material microstructure of the adhesive becomes more pronounced, and possible size effect phenomena can appear. This paper describes the mechanical behaviour of composites made of two solids, bonded together by a thin layer, in the framework of strain gradient and micropolar elasticity. The adhesive layer is assumed to have the same stiffness properties as the adherents. By means of the asymptotic methods, the contact laws are derived at order 0 and order 1. These conditions represent a formal generalization of the hard elastic interface conditions. A simple benchmark equilibrium problem (a three-layer composite micro-bar subjected to an axial load) is developed to numerically assess the asymptotic model. Size effects and non-local phenomena, owing to high strain concentrations at the edges, are highlighted. The example proves the efficiency of the proposed approach in designing micro-scale-layered devices. This article is part of the theme issue 'Non-smooth variational problems with applications in mechanics'. [ABSTRACT FROM AUTHOR]

The dynamic modulus of asphalt mixture is an important factor in the design of asphalt pavement, and many scholars have proposed different models for estimating the dynamic modulus of asphalt mixture, but there are almost no studies on the prediction of the dynamic modulus of semi-flexible materials. In order to analyze and estimate the dynamic modulus of semi-flexible materials, we set up a high-performance cementitious paste (HPCP) semi-flexible material and a reference group Stone Mastic Asphalt (SMA-16) under multiple conditions, first measured its dynamic modulus in the laboratory, and analyzed the dynamic modulus characteristics of the material, and then used the equation the estimation equation proposed by Witczak et al. (Witczak1-37A) as a benchmark to introduce a new parameter, grouting mass ratio (Pb) to develop a Witczak- G prediction model to compare and validate the predicted dynamic modulus with the measured values. The results show that compared with SMA-16, HPCP semi-flexible material exhibits higher dynamic modulus and lower phase angle, and its temperature sensitivity and deformation resistance are significantly better than those of SMA-16. Under the influence of porosity and Pb factor, the dynamic modulus is positively correlated with both factors, and the phase angle increases first and then decreases, showing strong elastic properties. In this paper, we propose a dynamic modulus prediction model based on viscosity and Pb, Witczak-G, which predicts the highest coefficient of determination (R2) of the predicted dynamic modulus as high as 0.99 after initial fitting and validation, which indicates that the Witczak-G model is suitable for predicting the dynamic modulus of semi-flexible materials injected with HPCP. [ABSTRACT FROM AUTHOR]