Search

In this work, the effect of random substitution modes of Fe and Ni on the stability and mechanical properties of Co3Ti-based intermetallics was investigated using first principles calculations through occupancy modes, electronic structures, energies, and elastic constants. The results show that FeCo type substitution favors ductility while NiCo type substitution favors strength. Compared to the above two types of substitution, FeTi type substitution is favorable for obtaining a balance between stability and ductility, but it is not easy to achieve energetically. Synergy of three types of substitutions enables stability and equilibrium mechanical properties of Co3Ti-based multi-component intermetallics. In addition, the anti-site substitution of neighboring Co and Ti atoms interchanging their positions may be a key step in the formation of FeTi type substitutions in terms of energy. This work provides useful data and insights into the design and utilization of Co3Ti-based multi-component intermetallics. [ABSTRACT FROM AUTHOR]

The thermomechanical behavior of materials is known to be sensitive to preexisting defects in their microstructure. In this paper, non-equilibrium molecular dynamics simulations have been used to investigate the effects of the microvoid size on the plastic deformation in single-crystal iron shock-compressed along the [ 001 ] crystallographic direction. The higher the microvoid radius, the faster the kinetics of dislocations. Thus, as the microvoid radius increases, the plastic activity evolves from a regime where the deformation is dominated by twin activities to a regime where both twin and dislocation activities play an essential role and then to a regime where the deformation is dominated by dislocation slip. Furthermore, in both defect-free and defective initial crystal states, the elastic precursor wave is observed to decay with propagation distance, resulting in a constitutive functional dependence of the yielding pressure, σ E , on the plastic deformation rate, ε ˙ p. In the regime where both deformation twinning and dislocation slip play important roles, the constitutive behavior is consistent with the original Swegle–Grady model and is in overall agreement with experimental data and thermomechanical simulations. [ABSTRACT FROM AUTHOR]

Meso-scale calculations of energy localization and initiation in energetic material microstructures must capture the deformation and collapse of pores and high-temperature shear bands, which lead to hotspots. Because chemical reaction rates depend sensitively on temperature, predictive continuum models need to get the pore-collapse dynamics and resulting hotspot temperatures right; this imposes stringent demands on the fidelity of thermophysical model forms and parameters and on the numerical methods employed to perform high-resolution meso-scale calculations. Here, continuum material models for β-HMX are examined in the context of shock-induced pore collapse, treating predictions from all-atom molecular dynamics (MD) simulations as ground truth. Using atomistics-consistent material properties, we show that the currently available strength models for HMX fail to correctly capture pore collapse and hotspot temperatures. Insights from MD are then employed to advance a Modified Johnson–Cook (M-JC) strength model, which is shown to capture key aspects of the physics of shock-induced localization in HMX. The study culminates in a MD-guided strength model for β-HMX that produces continuum pore-collapse results in better alignment on several aspects with those predicted by MD, including pore-collapse mechanism and rate, shear-band formation in the collapse zone, and temperature, strain, and stress fields in the hotspot zone and the surrounding material. The resulting MD-informed/MD-determined M-JC model should improve the fidelity of meso-scale simulations to predict the detonation initiation of HMX-based energetic materials in microstructure-aware multi-scale frameworks. [ABSTRACT FROM AUTHOR]

We employed all-atom molecular dynamics simulations to explore the mechanical response of bending, twisting, and overwinding for double-stranded DNA (dsDNA). We analyzed the bending and twisting deformations, as well as their stiffnesses, using the tilt, roll, and twist modes under stretching force. Findings indicate that the roll and twist angles vary linearly with the stretching force but show opposite trends. The tilt, roll, and twist elastic moduli are considered constants, while the coupling between roll and twist modes slightly decreases under stretching force. The effect of the stretching force on the roll and twist modes, including both their deformations and elasticities, exhibits sequence-dependence, with symmetry around the base pair step. Furthermore, we examined the overwinding path and mechanism of dsDNA from the perspective of the stiffness matrix, based on the tilt, roll, and twist modes. The correlations among tilt, roll, and twist angles imply an alternative overwinding pathway via twist–roll coupling when dsDNA is stretched, wherein entropic contribution prevails. [ABSTRACT FROM AUTHOR]

The cytoskeleton, a dynamic network of structural proteins within cells, is essential for cellular deformation and responds to external mechanical cues. Here, based on the structure of the cytoskeleton, combined with the biochemical reactions of the activator RhoA and the inhibitor F-actin, we develop a novel mechanochemical cytoskeleton model to investigate the mechanical behavior of cells. Interestingly, we find that active stress fibers exhibit diverse dynamical modes at specific inhibitor concentration thresholds. The existence of concentration differences and sustained mechanochemical feedback in activators and inhibitors trigger a global oscillation of isolated cells. In addition, under uniaxial and biaxial stretches, activators and inhibitors preferentially diffuse toward the more significantly deformed cytoskeletal elements, and their dynamic interactions regulate the cell to align with the main stretching direction. Our findings, consistent with many experimental results, provide fundamental insights into cytoskeletal remodeling and cellular mechanosensing mechanisms. [ABSTRACT FROM AUTHOR]

Flexible electronic devices with skin-like properties are hailed as revolutionary for the development of next-generation electronic devices, such as electric-skin and humanoid robotics. Graphene is intrinsically flexible due to its structural thinness in nature and are considered next-generation materials for wearable electronics. These devices usually experience a large mechanical deformation in use so as to achieve intimate conformal contact with human skin and to coordinate complex human motions, while heat dissipation has been a major limitation when the device is under a large mechanical strain. Unlike the small deformation (<1%) induced by intrinsic material factors such as lattice mismatch between material components in devices, a large mechanical deformation (>1%) by an external loading condition could lead to apparent changes to global geometric shapes and significantly impact thermal transport. In this study, we investigated the thermal conductivities of graphene under several large mechanical strains: 2.9%, 4.3%, and 6.1%. We used a refined opto-thermal Raman technique to characterize the thermal transport properties and discovered the thermal conductivities to be 2092 ± 502, 972 ± 87, 348 ± 52, and 97 ± 13 W/(m K) for the relaxed state, 2.9%, 4.3%, and 6.1% tensile strain, respectively. Our results showed a significant decreasing trend in thermal conductivities with an increasing mechanical strain. The findings in this study reveal new thermal transport mechanisms in 2D materials and shed light on building novel flexible nanoelectronic devices with enhanced thermal management. [ABSTRACT FROM AUTHOR]

Surface pattern formation of Smart Cut™ silicon-on-insulator (SOI) substrates is investigated using a new process derived from this technology. The local control of SOI surface roughness is achieved by using hetero-temperature surface activated bonding to introduce locally bespoke shear stresses into bonded silicon wafers. The finite element method is used to back up experimental measurements of these large deformations to determine the amount of shear stresses introduced into the structure, and to determine its impact on the fracture mechanism. [ABSTRACT FROM AUTHOR]

A gradient nano-grained (GNG) structure demonstrates satisfactory surface strength. However, the underlying mechanism responsible for its strengthening lacks sufficient research. To explain how gradient nano-grained structures improve surface strength in detail, large-scale parallel molecular dynamics simulations are utilized in this study to investigate the mechanical deformation behavior of BCC tungsten with varying grain sizes during spherical nanoindentation. The findings suggest that a well-designed gradient structure can promote rational plasticity and an appropriate distribution of internal atomic stress. The critical point of maximum stress and hardness is observed when the initial grain size is 4.5 nm, with an average grain size of 7.1 nm. The interaction between grain boundary slip and migration in small grains, along with the enhanced activity of grain boundary dislocations in large grains, collectively contributes to the enhancement of the strength and hardness of the GNG structure. Compared with a homogeneous nano-grained structure, the gradient nano-grained structure exhibits a more rational distribution of dislocations and stress relaxation effects to enhance strength. The present work utilizes the molecular dynamics nanoindentation method to study GNG materials, providing a methodology for investigating the surface strengthening effects of GNG structures at the atomic scale and effectively revealing potential mechanisms for resisting surface deformation in GNG structures. [ABSTRACT FROM AUTHOR]

Metallic glasses (MGs) are of high strength but limited plasticity at room temperature (RT) due to localized shear in the intrinsically heterogeneous structure. Here, we investigate the variation of structural heterogeneity and plasticity of a Zr-based MG after high-temperature (T) tension under different stresses (σ) at 579 K (0.9Tg, where Tg is the glass transition temperature). The correlation length (ξ) of the heterogeneous structure and the average Young's modulus ( E ¯ ) increase with σ when σ is below 160 MPa; when σ exceeds 160 MPa, both ξ and E ¯ decrease with σ, leading to the improvement of the plasticity. This research could be enlightening for improving the plasticity of MGs at RT through tuning their structural heterogeneity with high-T deformation. [ABSTRACT FROM AUTHOR]

A Belousov–Zhabotinsky (BZ) gel is a unique biomimetic system that undergoes autonomous volume oscillations induced by the redox oscillation of the BZ reaction. In a previous study, researchers reported that the oscillations of two BZ gels coupled by compression were synchronized by a mechanical interaction. They mathematically explained the synchronization behavior using a phase oscillator model. As a different approach to the previous study, a physicochemical investigation of the phenomenon will lead to a better understanding of the functional biological rhythms essential for life. In this study, we construct a simple phenomenological model to understand the synchronization of BZ gels. The model consists of two parts. One is the dynamics of the chemical reactions in the BZ gels. We use a phenomenological model based on the Oregonator for the BZ reaction. The other is the dynamics of the mechanical deformation of the BZ gel. Using approximations, we extract the parameters essential for the synchronization of a mechanical interaction. Thus, we can derive a novel equation for the deformation dynamics of mechanically coupled BZ gels. By combining these two parts, we perform numerical calculations. This allows us to find that the synchronization of the two BZ gels is less likely to occur under stronger compression. We explain this trend through one physicochemical parameter in our model: the volume fraction of the BZ gel in the reduced state. [ABSTRACT FROM AUTHOR]

This paper utilizes a coupled chemomechanical model that integrates chemical reactions, diffusion, and mechanical deformation to describe the high-temperature interfacial reactions and stress evolution within an enamel coating/Ni-based super-alloy system. Through finite element simulation, we conduct a comprehensive analysis of multiple reactions and processes at the interface. Experimental characterization of the concentration distribution of various elements is employed to verify the accuracy of the proposed chemomechanical model. Additionally, the simulation reveals that the interface region experiences compressive circumferential stress, which can potentially lead to interfacial failure due to buckling. On the other hand, the enamel coating undergoes tensile circumferential stress, resulting in the formation of vertical surface cracks. These findings hold practical implications for the development of advanced coatings with enhanced durability and performance. Future research can further optimize coating design and enhance the reliability of high-temperature applications based on these results. [ABSTRACT FROM AUTHOR]

In this paper, a Zr–5W alloy was fabricated via casting. In order to obtain the mechanical properties of the material, quasi-static compression tests at room temperature and split Hopkinson pressure bar tests at various temperatures were carried out. The x-ray diffraction result showed that the main components of the alloy were αZr and W2Zr, where αZr is the matrix and W2Zr is the reinforcement. The metallographic characterization results showed that there were two main forms of W2Zr in the material, namely, large particle boundary and small diffuse submicrometer precipitates. The reinforcements of both distributions have the effect of increasing the strength of the material, but the small submicrometer W2Zr precipitates would cause microcrack nucleation during the late plastic deformation stage, resulting in damage softening. In order to make theoretical calculations of the mechanical properties of materials, the Johnson–Cook (JC) constitutive model and Zerilli–Armstrong (ZAM) constitutive model of the material were obtained. It was found that the JC constitutive model had poor consistency in describing material properties. Although the consistency of the ZAM constitutive model was higher than that of the JC constitutive model, it still had obvious shortcomings. Combined with the deformation mechanism of the alloy, a modified constitutive relation was established by adding damage softening terms based on the hexagonal close-packed metal constitutive model inferred by the kinetics of heat-activated dislocations. The relative error results of all working conditions show that the correlation consistency of the improved constitutive model in this paper is significantly better than that of JC constitutive and ZAM constitutive. [ABSTRACT FROM AUTHOR]

Van der Waals (vdW)-layered materials, such as graphite, exhibit unique mechanical properties owing to their structural and mechanical anisotropies. This study reports the development of a mechanical model that reproduces the characteristics of the nonlinear and reversible bending deformation of vdW-layered materials, while taking into account the microscopic mechanism of the discrete interlayer slips. The vdW-layered material was modeled as a stack of interacting discrete deformable layers (semi-discrete layer model), and the interlayer interaction was modeled using a cohesive zone model that reproduced the localized interlayer slip. Using the finite-element method, out-of-plane bending deformation analyses were performed on the cantilevers of the highly oriented pyrolytic graphite (HOPG) and MoTe2, and the validity of the model was verified by comparing it with the experimental results. The model accurately reproduced the loading and unloading behaviors in the experiments for the submicron HOPG cantilevers or the large nonlinear and reversible deformation with a hysteresis loop. Furthermore, the model reproduced well the characteristics of the bending experiments for the micro-MoTe2 cantilevers, or the intermittent decrease in stiffness during the loading process and deformation restoration during the unloading process. These results demonstrated that the designed semi-discrete layer model can be universally applied to reproduce the bending deformation characteristics of a variety of vdW-layered materials and can be employed to effectively elucidate the underlying deformation mechanisms. [ABSTRACT FROM AUTHOR]

Utilizing molecular dynamics simulation, this study aims to explore the phase transformation behavior of porous nanocrystalline (NC) NiTi shape memory alloys (SMAs) when subjected to cyclic deformation. The influences of porosity and cyclic deformation on the phase transformation of NC NiTi SMAs are examined and discussed. The simulation results show that the increase in the porosity and number of cycles leads to a decrease in both the critical phase transformation stress and peak stress whereas an increase in the residual martensite, phase boundary, and interstitial atoms; the related results can be supported by previous experiments. After cyclic deformation, the reduction in the potential energy for the entire system during the tensile phase occurs at an earlier stage, indicating that the martensitic transformation occurs earlier as the number of cycles increases. Notably, the dissipated energy demonstrates a decrease with an increasing number of cycles, and the potential energy during the austenite elastic unloading stage undergoes a transition from a decreasing to an increasing trend due to the presence of residual martensite increasing with the number of cycles. [ABSTRACT FROM AUTHOR]

A coupled Mori-Tanaka/finite element strategy was implemented to capture deformation profiles of aluminum AA 6063 cylindrical and hexagonal tubes reinforced with 60% variable coir-fiber thickness (5 mm, 10 mm) coir-fiber under variable oblique crushing. By a representative volume element (RVE) defined elastic moduli of the reinforcement phase hybrid tubes were simulated for the effect of reinforcement layer thickness under the Johnson-Cook's and Hashin's intralaminar damage with cohesive zone modeling. As, transformations in deformation underscored variabilities in shape, multicellularity and reinforcement thickness, a correlation is found between loading angles and peak crushing forces in evolving a lightweight absorber consistent with extreme oblique impacts. [ABSTRACT FROM AUTHOR]

Stretching separation and reflexive separation are two collision regimes that give rise to satellite droplets, significantly impacting the droplet size distribution. However, the influence of high pressure on these regimes remains unclear. This paper investigates the collision dynamics of binary equal-size droplets under varying ambient pressures using the volume of fluid method and adaptive mesh refinement. The results show that vortices, generated during droplet motion changes or ligament ruptures, facilitate mass transport within the droplet–droplet deformation. Additionally, this paper summarizes four phases of droplet deformation in the separation regimes, which are delayed in stretching separation and advanced in reflexive separation with increasing ambient pressure. Elevated ambient pressure restricts droplet movement, resulting in tougher ligament fractures, smaller satellite droplets, and an expanded coalescence regime boundary. Unlike previous works, this paper incorporates gas kinetic and dissipation energies during droplet collisions at high pressures, revealing that at 7 MPa, the gas dissipation energy is comparable to the liquid dissipation energy and cannot be neglected. To account for these effects, a pressure-dependent formula is integrated into the composite collision model under the Lagrangian framework, offering enhanced predictions of droplet size within the stretching separation regime. [ABSTRACT FROM AUTHOR]

CaBi 4 Ti 4 O 15 (CBT) ceramics are promising piezoelectric materials that have been widely studied for high-temperature applications. Despite significant advancements in the electrical performance of CBT ceramics, the understanding of their mechanical behaviors remains limited, which is unfavorable for designing ceramics with high stability and reliability during high-temperature service. This work investigated the mechanical properties and fracture behaviors of Nb/Mn co-doped CaBi 4 Ti 4 O 15 (CBTNM) with various doping levels, focusing on stress-strain responses and ferroelastic deformation behaviors under uniaxial compression and multi-field coupling conditions. HRTEM analysis reveals small-scale layered domain wall structures on the surface of plate-like grains. The fracture and compressive strengths of CBTNM ceramics initially decrease and then increase with an increase in doping content, and the underlying mechanisms are related to grain size, defects, and densification. CBTNM ceramics exhibit nonlinear stress-strain responses due to ferroelastic deformation under compressive loading, and the resultant irreversible domain switching strain increases with an increase in doping content, while poling can further increase the residual strain. Under multi-field loading conditions, CBTNM ceramics undergo more ferroelastic deformation events and exhibit larger residual strain. The micro-cracks, pores, complicated fracture modes, and degraded fracture surfaces with fragmental and rough features are mainly responsible for the lower elastic modulus and inferior mechanical response. This work enhances our understanding of the mechanical behaviors of high-temperature piezoelectric ceramics and provides guidance for designing high-performance piezoelectric materials for complex environmental applications. [ABSTRACT FROM AUTHOR]

The hazelnut possesses a significant economic value and is extensively consumed on a global scale. Physico-mechanical properties such as linear dimensions, deformation, force, stress, and energy play an important role in the processing of hazelnut and hazelnut kernels, quality assessment, and the development of harvesting and post-harvest technologies. The data used in the data set was determined by applying compression tests and artificial neural networks, support vector regression, and multiple linear regression methods were applied to the data obtained. The aim of the study ws to determine the deformation energy of hazelnuts and hazelnut kernels based on some mechanical properties of hazelnuts using nondestructive machine learning methods instead of traditional measurement methods with minimum error, minimum labor, and in the shortest time. The average R2 for kernels and hazelnuts was ANN 95.2%, SVR 89.6%, and MLR 86.1%. The average MSE for kernels and hazelnuts was ANN 0.006, SVR 0.012, and MLR 0.072. The machine learning methods used in the study provided results close to the ideal statistical metrics. According to the analyses of the machine learning methods, results similar to the optimal statistical metrics were obtained. The most successful and least-error methods were the artificial neural network, support vector regression and multiple linear regression, respectively. [ABSTRACT FROM AUTHOR]

It has been observed in experiments that, for some materials, when a sheet is subjected to increasing equal biaxial tensile forces on its edges, its deformation can change from homogeneous equal biaxial extension to homogeneous unequal biaxial extension. Such response has been analyzed in the literature as a bifurcation from the base deformation to a new deformation. The analyses have used a constitutive equation that expresses the stress tensor as a function of a deformation tensor. The present work is concerned with analyzing this bifurcation using a new class of constitutive equations in which the deformation tensor is expressed as a function of the stress tensor. Using such a model for an incompressible isotropic nonlinear elastic material, a condition is derived for determining when during an equal biaxial extension of a sheet, there is a bifurcation into an unequal biaxial extension. An example is provided using a constitutive equation that has been fit to experimental data. [ABSTRACT FROM AUTHOR]

This study presents comprehensive numerical modeling methods for simulating early‐age stress (EAS) relaxation in cementitious materials, based on the autogenous deformation (AD), elastic modulus, creep, and stress continuously tested by a mini temperature stress testing machine (Mini‐TSTM) and a mini AD testing machine from a very early age (i.e., from a few hours to a week). Four methods for converting creep compliance to relaxation modulus were discussed in detail and used for the one‐dimensional (1D) and three‐dimensional (3D) simulation of stress evolution in the Mini‐TSTM test. Furthermore, virtual creep and relaxation tests were conducted using an exponential algorithm with either the Kelvin or Maxwell chains to show their applicability in simulating the viscoelastic behavior of early‐age cementitious materials. The results showed that the exponential algorithm with the Maxwell chain using an exponential conversion function from creep to relaxation obtains good prediction accuracy of EAS in 3D analysis. The numerical solutions of the Volterra integral of creep compliance can lead to a negative relaxation modulus, thus introducing stress calculation errors in both 1D and 3D analysis. [ABSTRACT FROM AUTHOR]

The flow and deformation of cement-based materials accompanies the full cycle of three-dimensional concrete printing (3DCP) and profoundly affects the quality of printed structures. Therefore, rheology is closely related to 3DCP technology. However, since printing materials undergo complex changes (from fluid to solid) during the entire process, it is extremely difficult to obtain the rheological parameters of the material accurately, which makes it difficult to characterise the material's properties and explore the rheological laws within the technical cycle. In this regard, this article starts from the perspective of rheology, systematically reviews the performance requirements of 3DCP technology for printing materials, critically discusses the existing methods for characterisation of material printability, including various conventional and unconventional methods, and clarifies the scope of application of each method. In addition, this article introduces several buildability models based on consideration of the time dependency of the printing material and indicates the direction for the optimisation of the performance of printing materials. [ABSTRACT FROM AUTHOR]

We present a mid-Late Cretaceous to present day tectonic reconstruction model for Aotearoa-New Zealand. Our GPlates model comprises 50 rigid crustal blocks grouped into regions with common deformation histories set within a well-defined Australia-Pacific-Antarctica plate circuit tied to a published global paleomagnetic absolute reference frame. Within the model, four distinct periods of deformation are recognised from both near- and far-field observations. A key model assumption is the continuity of basement terranes between North and South Zealandia prior to Middle Eocene rifting and Late Oligocene initiation of transform motion. To complement the rigid crustal block model, continuously closing polygons show a ∼25% decrease in plate boundary area since the Middle Eocene that has been compensated for by corresponding increases in crustal thickness. A kinematic fault-propagation fold model demonstrates the plausibility of post-Late Oligocene asymmetric oroclinal folding on both sides of the evolving transform boundary. 'Missing' areas of map section common to previous tectonic reconstructions can be reconciled through contraction, elongation and vertical-axis rotation of continental crust within the deformation zone ahead of northward propagation of the Alpine Fault. This tectonic reconstruction model provides an open, accessible, and testable foundation for current and future paleogeographic and tectonic studies across Zealandia. [ABSTRACT FROM AUTHOR]

The Dabashan Fold‐and‐Thrust Belt is an important natural laboratory for exploring the Meso‐Cenozoic intracontinental orogenic evolution in China. Due to the severe lack of post‐Early Cretaceous strata, little attention has been paid to Cenozoic tectonic in the Dabashan. This study presents structural analysis, in‐situ U‐Pb dating of calcite in conjunction with petrographic and stable isotopic analyses along the eastern segment of the Chengkou Fault in the Dabashan. Structural analysis coupled with U‐Pb dating of syn‐kinematic calcite slickenfibres suggests two discrete S‐N compressional strike‐slip deformation events associated with localized E‐W extension along the eastern segment of the Chengkou Fault have occurred at the Early Eocene (~57–50 Ma) and Late Oligocene‐Early Miocene (~23–17 Ma), respectively. We tentatively related the Cenozoic deformation events in the study area to the clockwise rotation of the Sichuan Basin, resulting from the combined far‐field stress effects between the India, Eurasia and western Pacific plates. [ABSTRACT FROM AUTHOR]

This research aims to establish the semi-analytical approach for nonlinear dynamic buckling and vibration responses of functionally graded graphene platelet reinforced composite (FG-GPLRC) circular plates and spherical shells subjected to time-dependent radial pressure and thermal loads. The higher-order shear deformation theory with von Karman's nonlinearities and the nonlinear viscoelastic foundation model is used to establish the expression of the fundamental equations of considered structures. The shells and plates are considered with clamped and immovable edge, and shallow curvature of the shells is applied. The Lagrange function is applied to establish the total energy of structures, and the potential function of viscous damping of the viscoelastic foundation is expressed using the Rayleigh dissipation function. The motion equation of the structures can be formulated using the Euler–Lagrange function. The dynamic responses are obtained using the numerical method, and the critical dynamic buckling loads are obtained using the dynamic buckling criterion of Budiansky–Roth. The large effects of material parameters, geometrical parameters, and nonlinear viscoelastic foundation on dynamic responses of considered structures are investigated and discussed in many numerical examples. [ABSTRACT FROM AUTHOR]

The physical cementation and grain breakage effects play a vital role in influencing the mechanical properties of hydrate-bearing sediment. In this study, a thermodynamic model for hydrate-bearing sediment considering stress history, grain breakage, and drainage condition is developed based on granular thermodynamic and critical state theory. The concept of breakage ratio is defined and incorporated into the critical state line to capture the grain breakage effect under a large range of confining pressures. To describe the structural effects induced by cementation and stress history, a new cementation degradation term and the structure factor of stress history are incorporating into the elastic potential function. By employing a rigorous parameter calibration approach, the theoretical model is applied and verified under various stress histories, hydrate saturations, and confining pressures, and a comparison is drawn between with/without considering grain breakage effect. The theoretical model, accounting for the grain breakage effect, demonstrates superior prediction accuracy and can reflect the inhibitory effect of hydrate saturation on grain breakage under high stress, as well as the strength and deformation characteristics under diverse drainage conditions and stress histories. [ABSTRACT FROM AUTHOR]

Several regularized formulations exist in the literature, such as nonlocal constitutive models, for the objective simulation of localized deformations in quasibrittle materials that prevent the well-known pathological dependence on the employed mesh. Although they usually require a significant discretization to represent the localization zone of a given material, characterized by some length scale linked to its microstructure, scaling techniques exist to derive representative parameters for full-scale simulation of geotechnical problems. However, the softening response observed in conventional triaxial or uniaxial compression tests is not solely a constitutive feature but also the result of a complex boundary value problem (BVP), where the specific localization pattern formed affects the global response of the experiment. Therefore, constitutive softening parameters should be backcalculated through the simulation of a given laboratory test as a BVP. However, as demonstrated in this paper, the cylindrical geometry of the samples in conventional tests hinders the onset of localization, resulting in a stiffer response that underestimates the resulting nominal softening rate. Within this context, the paper aimed to demonstrate the complexity and difficulty in the determination of a softening rate for nonlocal constitutive models from data of conventional triaxial tests performed on cylindrical specimens and to provide relevant insights toward a practical procedure for the determination of parameters in regularized simulations of quasibrittle geomaterials for practical applications. [ABSTRACT FROM AUTHOR]

The use of heaving and pitching fins for underwater propulsion of engineering devices poses an attractive outlook given the efficiency and adaptability of natural fish. However, significant knowledge gaps need to be bridged before biologically inspired propulsion is able to operate at competitive performances in a practical setting. One of these relates to the design of structures that can leverage passive deformation and active morphing in order to achieve optimal hydrodynamic performance. To provide insights into the performance improvements associated with passive and active fin deformations, we provide here a systematic numerical investigation in the thrust, power, and efficiency of 2D heaving and pitching fins with imposed curvature variations. The results show that for a given chordline kinematics, the use of curvature can improve thrust by 70% or efficiency by 35% over a rigid fin. Maximum thrust is achieved when the camber variations are synchronized with the maximum heave velocity, increasing the overall magnitude of the force vector while increasing efficiency as well. Maximum efficiency is achieved when camber is applied during the first half of the stroke, tilting the force vector to create thrust earlier in the cycle than a comparable rigid fin. Overall, our results demonstrate that curving fins are consistently able to significantly outperform rigid fins with the same chord line kinematics on both thrust and hydrodynamic efficiency. [ABSTRACT FROM AUTHOR]

Buffer energy absorbing structures have very high use value in daily life, industrial production, aerospace and other fields. Cylindrical shells are used as a highly efficient buffer and energy absorbing structure due to their own structure and good mechanical properties. Taylor impact experiments were conducted on three types of structural cylindrical shells (non grooved, inner grooved, and outer grooved) and numerical model was also established to study and analyze the dynamic response characteristics of the three types of structural cylindrical shells. Finally, the deformation mechanism of the cylindrical shell was analyzed theoretically to explore the impact of grooving treatment on the deformation of the cylindrical shell. The results show that with the increase of impact velocity, the length of the cylindrical shells of the three structures decreased, and the diameter of the impact end and the maximum diameter increased. Each of the three specimens had a convergence velocity(convergence velocity: The impact end diameter of cylindrical shell is the initial impact velocity at the maximum diameter), that is, when the impact velocity was greater than or equal to the convergence velocity, its maximum diameter was equal to the diameter of the impact end. When the impact velocity exceeded a certain value, the deformation modes of the three types of cylindrical shells changed. The comparison of experimental and simulation results proved the effectiveness of the numerical model. The maximum stress was always above the impact end face. It was concluded from the theoretical analysis Due to the stress concentration at the groove, the stress distribution and internal stress distribution of the cylindrical shell were affected, which in turn affected the deformation and energy absorption capacity of the cylindrical shell. At the same impact velocity, the outer grooved cylindrical shell has the shortest buffer time and the BW specimen had the most gentle buffer curve before 35μs. [ABSTRACT FROM AUTHOR]

The rare earth element Gd was added into a resulfurized steel to enhance its performance. Non-metallic inclusions in the steel, the hardness and the microstructure of the steel were analyzed. The addition of Gd resulted in the formation of Gd–O–S and Gd–S inclusions which served as cores of MnS inclusions so that the resistance to the deformation of inclusions was improved. When the content of the total gadolinium (T.Gd) increased from 0 to 198 ppm, the hardness of the steel matrix increased from 60.4 to 80.4 HRA. The microstructure predominantly consisted of a substantial number of pearlites with a minor presence of ferrites distributed in a network-like pattern. The distribution of ferrites along the grain boundary was weakened when the T.Gd content in the steel was 79 ppm. The tensile fracture of the steel exhibited a mixed ductile-brittle pattern while its impact fracture displayed brittle characteristics. [ABSTRACT FROM AUTHOR]

Solidification end reduction is an effective approach to control the central porosity during continuous casting of round bloom, although it is not widely reported. In the present work, a three-dimensional finite element model has been developed with coupling heat transfer and mechanical deformation for a φ690 mm continuously cast round bloom, and verified by the surface temperature, shrinkage zone width, reduction crack location, and deformed contour shape. It is found that the contact width between roller and the bloom increases with the increase of reduction amount and approximately in a parabolic relationship. To cover the whole range of the shrinkage zone, the total reduction amount should not be smaller than 25 mm as the width of the shrinkage zone is about 120 mm. The bulge width along the horizontal direction during reduction increases as the total reduction amount increases, and the relationship can be fitted by a parabolic equation. The reduction thickness in the shrinkage zone is larger when the reduction amount is higher, and it also follows parabolic relationship. The deformation in the shrinkage zone is more obvious when the reduction is conducted before crater end. The reduction efficiency for φ690 mm round bloom before solidification is between 20 and 30 pct, while after solidification is roughly between 12 and 20 pct. It increases with the increase of apparent reduction amount, mainly related to the increase of the strain rate. The deformation of the shrinkage zone in φ690 mm round bloom with 30 mm apparent reduction in continuous casting and hot rolling has been compared. The equivalent strain in the shrinkage zone of the round bloom in continuous casting is about 0.047 to 0.052, while that in hot rolling is about 0.031 to 0.036, indicating the reduction efficiency of the former is about 1.5 times higher than the latter. [ABSTRACT FROM AUTHOR]

In Bonito (J. Comput. Phys. 448:110719, 2022), a local discontinous Galerkin method was proposed for approximating the large bending of prestrained plates, and in Bonito (IMA J. Numer. Anal. 43:627-662, 2023) the numerical properties of this method were explored. These works considered deformations driven predominantly by bending. Thus, a bending energy with a metric constraint was considered. We extend these results to the case of an energy with both a bending component and a nonconvex stretching component, and we also consider folding across a crease. The proposed discretization of this energy features a continuous finite element space, as well as the discrete Hessian used in Bonito (J. Comput. Phys. 448:110719, 2022; IMA J. Numer. Anal. 43:627-662, 2023). We establish the Γ -convergence of the discrete to the continuous energy and also present an energy-decreasing gradient flow for finding critical points of the discrete energy. Finally, we provide numerical simulations illustrating the convergence of minimizers and the capabilities of the model. [ABSTRACT FROM AUTHOR]

Reduced-order simulation is an emerging method for accelerating physical simulations with high DOFs, and recently developed neural-network-based methods with nonlinear subspaces have been proven effective in diverse applications as more concise subspaces can be detected. However, the complexity and landscape of simulation objectives within the subspace have not been optimized, which leaves room for enhancement of the convergence speed. This work focuses on this point by proposing a general method for finding optimized subspace mappings, enabling further acceleration of neural reduced-order simulations while capturing comprehensive representations of the configuration manifolds. We achieve this by optimizing the Lipschitz energy of the elasticity term in the simulation objective, and incorporating the cubature approximation into the training process to manage the high memory and time demands associated with optimizing the newly introduced energy. Our method is versatile and applicable to both supervised and unsupervised settings for optimizing the parameterizations of the configuration manifolds. We demonstrate the effectiveness of our approach through general cases in both quasi-static and dynamics simulations. Our method achieves acceleration factors of up to 6.83 while consistently preserving comparable simulation accuracy in various cases, including large twisting, bending, and rotational deformations with collision handling. This novel approach offers significant potential for accelerating physical simulations, and can be a good add-on to existing neural-network-based solutions in modeling complex deformable objects. [ABSTRACT FROM AUTHOR]

While there have been previous works that explored methods to enhance the aesthetics of images, the automated beautification of 3D shapes has been limited to specific shapes such as 3D face models. In this paper, we introduce a framework to automatically enhance the aesthetics of general 3D shapes. Our approach employs a reference-based beautification strategy. We first performed data collection to gather the aesthetics ratings of various 3D shapes to create a 3D shape aesthetics dataset. Then we perform reference-based editing to edit the input shape and beautify it by making it look more like some reference shape that is aesthetic. Specifically, we propose a reference-guided global deformation framework to coherently deform the input shape such that its structural proportions will be closer to those of the reference shape. We then optionally transplant some local aesthetic parts from the reference to the input to obtain the beautified output shapes. Comparisons show that our reference-guided 3D deformation algorithm outperforms existing techniques. Furthermore, quantitative and qualitative evaluations demonstrate that the performance of our aesthetics enhancement framework is consistent with both human perception and existing 3D shape aesthetics assessment. [ABSTRACT FROM AUTHOR]

We propose MiNNIE, a simple yet comprehensive framework for real-time simulation of nonlinear near-incompressible elastics. To avoid the common volumetric locking issues at high Poisson's ratios of linear finite element methods (FEM), we build MiNNIE upon a mixed FEM framework and further incorporate a pressure stabilization term to ensure excellent convergence of multigrid solvers. Our pressure stabilization strategy injects bounded influence on nodal displacement which can be eliminated using a quasiNewton method. MiNNIE has a specially tailored GPU multigrid solver including a modified skinning-space interpolation scheme, a novel vertex Vanka smoother, and an efficient dense solver using Schur complement. MiNNIE supports various elastic material models and simulates them in real-time, supporting a full range of Poisson's ratios up to 0.5 while handling large deformations, element inversions, and self-collisions at the same time. [ABSTRACT FROM AUTHOR]

The collapse-prone nature of eucalyptus wood has implications for the measurement of drying rheological characteristics, particularly free shrinkage. The study outlined the calculation method for drying strain and the determination of drying stress direction. It also analyzed the free shrinkage properties of the wood, as well as the variations in elastic strain, viscoelastic strain, and mechano-sorptive creep strain throughout the drying process. The findings indicate the following: 1, there were no significant differences in free tangential shrinkage between the layers of the specimens. 2, the free tangential shrinkage of the layers was greater than that of the specimens. 3, the use of fresh thin wood that has not been subjected to drying stresses was recommended for accurate measurement of free shrinkage strains, as steaming does not fully reverse the plasticizing deformation caused by drying. 4, the collapse of eucalyptus wood in the early stages of drying hindered the reversal of tensile strain in elastic, viscoelastic, and mechano-sorptive behaviors. [ABSTRACT FROM AUTHOR]

In this paper, small-scale testing techniques—nanoindentation and micropillar compression—were used to investigate the deformation mechanisms, size effects, and strain rate sensitivity of (100) and (110) single-crystal Gum Metal at the micro/nanoscale. It was observed that the (100) orientation exhibits a significant size effect, resulting in hardness values ranging from 1 to 5 GPa. Conversely, for the (110) orientation, this effect was weaker. Furthermore, the yield strength obtained from the micropillar compression tests was approximately 740 MPa for the (100) orientation and 650 MPa for the (110) orientation. The observed deformations were consistent with the established features of the deformation behavior of body-centered cubic (bcc) alloys: significant strain rate sensitivity with no depth dependence, pile-up patterns comparable to those reported in the literature, and shear along the {112}<111> slip directions. However, the investigated material also exhibited Gum Metal-like high ductility, a relatively low modulus of elasticity, and high yield strength, which distinguishes it from classic bcc alloys. [ABSTRACT FROM AUTHOR]

The three-dimensional (3D) stress waves of coal samples were studied using a true triaxial split Hopkinson pressure bar compression rod. The results indicate that the 3D strain of the coal samples increased gradually under vibration load. The 3D stress wave of coal samples showed attenuation characteristics, and the change amplitude of the stress wave of coal samples along the direction of dynamic load was the most obvious. The amplitude of stress wave was the largest in the axial direction constrained by pre-stressing 3 MPa, while the amplitude of stress wave in the lateral 2 MPa pre-stressing was smaller than that under the constraint of 1 MPa. The results showed that the main deformation of coal samples was along the impact direction, while the larger horizontal and vertical lateral binding forces limited the deformation of coal samples. The Fourier transform was performed on the 3D stress wave of the coal samples, and the change in the amplitude of the stress wave spectrum was correlated positively with the vibration. The spectrum amplitude of the coal samples under the pre-stressed 3 MPa constraint (axial) direction was the largest, while the spectrum amplitude of the coal samples under the lateral 2 MPa pre-stressed constraint was smaller than that under the binding 1 MPa. However, the main frequency of the three-way stress wave was distributed in 0–10 kHz. By calculating the energy consumption rate and wave velocity decay rate, it was verified that the damage of coal samples increased with increase in dynamic load. This experimental testing provides an effective testing method for studying the 3D stress waves of coal samples under complex stress medium conditions. In addition, a dynamic constitutive model of coal was constructed according to the mechanical behavior of coal and rock mass and the measured data. [ABSTRACT FROM AUTHOR]

Understanding the deformation mechanism in polycrystalline metals is critical to use them in high-value high-risk applications. Here, we report an automated framework based on lattice rotation analysis for accurately identifying slip system and assessing the multiple slip activities in large data set of polycrystalline Zr, aims to statistically provide deep insight on deformation mechanism of Zr. Results show that multiple slip is the dominant slip system rather than single slip system. This method can be applied as a complementary method to the intragranular misorientation axis (IGMA) method and can act as bridges between macro-mechanical response and microstructural deformation mechanisms. [ABSTRACT FROM AUTHOR]

The article concerns the modeling of the transverse impact of an impactor (test sample) on the surface of an infinite elastic layer. The Laplace transform with respect to time and the Hankel transform with respect to the radius for the axisymmetric case were applied. The propagation of elastic waves in the layer and local deformations in the contact zone are taken into account. Impact force, impact time and the coefficient of restitution were examined. The results are compared with the elastic half-space. The calculations carried out showed that for layer thicknesses of more than five impactor diameters, the layer can be considered as a half-space. [ABSTRACT FROM AUTHOR]

The embryo of Volvox globator, a monolayer spheroidal cell sheet, undergoes an inversion to release its flagella during the late stage of its development. This inversion, known as the type-B inversion, initiates from the equator. Other types of inversions also exist, such as the inversion from the anterior pole of Volvox carteri and the bowl-shaped inversion of Pleodorina. These inversions can be regarded as axisymmetric processes, during which complex fold patterns are generated. The invagination of the cell sheet plays a crucial role in embryonic development, and our aim is to understand this process from an interdisciplinary point of view, with a particular focus on the mechanical aspects. In this work, we first develop a morphoelastic shell theory for general deformations of biological shells, incorporating both active and passive biomechanical effects, as well as membrane and bending effects. By means of asymptotic analysis, we establish an analytical framework to study axisymmetric deformations of morphoelastic shells focusing mainly on the membrane effects. For illustrative purposes, we apply this framework to investigate the invagination of Volvox globator embryo. The underlying active stretches driving this process are derived analytically by inverse analysis of experimental data through the morphoelastic shell model. We highlight a two-order remodeling strategy that generates the observed invagination pattern: the Gaussian morphing of the cell sheet creates the first fundamental form of the stress-free folded patterns, while a secondary remodeling generates the membrane tension necessary to balance the external pressure and the second fundamental form of the invaginated pattern. This remodeling strategy unveils the complex interplay between geometry, mechanics, and biological processes during Volvox globator embryogenesis. [ABSTRACT FROM AUTHOR]

The micro-bond potential and stress tensor in Peridynamics are examined. A new form of the 3D micro-bond potential is proposed in terms of the components of the bond length change. The present micro-bond potential provides a new route to unifying the classical 3D bond-based and ordinary state-based Peridynamics, and it also appears to be central to developing potential-based bond failure criteria, especially for the ordinary state-based Peridynamics. Besides, a new measure of Peridynamic stress is introduced. Different from the available Peridynamic stress tensors, the present Peridynamic stress is derived from the deformation state in a direct way and equivalent to the Cauchy stress to some extent. Moreover, the Peridynamic partial stress is critically reexamined. Straightforward proof shows the exact relationships among the Peridynamic partial stress, the present Peridynamic stress and the first Piola stress. [ABSTRACT FROM AUTHOR]

Enhancing the strength and ductility of metallic materials simultaneously is crucial for numerous industrial applications, yet it remains a formidable challenge due to the typical trade-off between these two properties. This study introduces an innovative approach to surmount this challenge by employing a composite bar design that leverages necking inhibition mechanisms for simultaneous improvements in both strength and ductility. The composite bars, comprising aluminum cores reinforced with spirally wound fiber-reinforced polymer (FRP) strands, were fabricated in various configurations to investigate different necking behaviors. Through uniaxial testing, the composite bars exhibited notable increases in both strength and ductility, attributed to the strategic design of the FRP winding angle and FRP content. This design effectively modulates the necking behavior, thereby enhancing the composite bars' mechanical properties. Analysis of the strain distribution further elucidated the role of the spiral FRP strands in necking prevention. The composite bar design method outlined in this study offers a viable strategy for enhancing the mechanical performance of metallic materials, significantly reducing the risk of abrupt failure under high loads and deformations. [ABSTRACT FROM AUTHOR]

The rise of flexible electronics has sparked a demand for components, such as loudspeakers, that seamlessly integrate into various applications while maintaining their performance. However, current loudspeakers typically rely on electromechanical systems, necessitating significant space for components such as coils and magnets. This limits their flexibility and usage in thin, conformable devices. To address this, a paper‐based thermoacoustic (TA) loudspeaker utilizing carbon nanotubes (CNTs) via inkjet printing is introduced. This TA loudspeaker demonstrates exceptional flexibility and durability, maintaining high acoustic performance across human‐audible frequencies up to 20 kHz, even when subjected to extensive mechanical deformation. Additionally, employing inkjet printing technology streamlines their manufacturing processes, offering a cost‐effective solution with scalability for mass production. Furthermore, an origami‐inspired 3D folding architecture enhances the loudspeaker's portability and enables versatile shape configurations, thus broadening its utility across electronic devices. These demonstrations offer a potential solution for next‐generation audio systems in flexible electronics. [ABSTRACT FROM AUTHOR]

An affected layer will be formed on workpiece surface in grinding process, which affects the fatigue strength and life. The simulation and experiment were used to study the grinding force, grinding temperature field, stress field, strain field, as well as the characteristics of the affected layer (residual stress, microhardness, and microstructure) in grinding AerMet100 with white alumina grinding wheel and CBN grinding wheel. The variation law of the grinding force, grinding temperature, equivalent stress field, and equivalent strain field during the grinding process and their influence on the formation of surface affected layer were revealed. The results show that the ground surface is mainly affected by grinding heat, while the grinding sub surface (i.e., plastic deformation zone) is greatly affected by plastic tensile (or compression) effect of grinding force; the microstructure of the ground surface deviates along the grinding direction and presents fibrous structure, with grain elongation, and when the grinding parameters are large, a white layer structure appears on the ground surface; the temperature rise softening effect for surface microhardness is the dominant factor with the white alumina grinding wheels; the metal strengthening effect for surface microhardness caused by mechanical plastic deformation of grinding force is the dominant factor with the CBN grinding wheels; for the white alumina grinding wheels, the residual tensile stress caused by grinding heat is relatively significant; for the CBN grinding wheel, the grinding surface generally presents residual compressive stress, and the residual compressive stress caused by mechanical plastic deformation caused of grinding force plays a dominant role. [ABSTRACT FROM AUTHOR]

In recent years, the application of non-uniform pressure in flexible-die forming, such as viscous pressure forming and magnetorheological pressure forming, has become increasingly prevalent in manufacturing thin-walled components. Non-uniform pressure is primarily employed to change the shape of the sheet, while its effects on thickness reduction and fracture behaviors remain intricate. In this study, the mechanisms of non-uniform pressure to decrease thickness reduction and delay fracture instability in bulge forming are revealed. Non-uniform pressure changes the principal stresses, resulting in distinct deformation behaviors. Numerical simulations indicate that both too large and too small pressure weights lead to severe thickness thinning and increase the risk of fracture instability. Theoretical equations of the polar strain and instability strain are derived to reveal the mechanisms. The characteristics of non-uniform pressure to decrease thickness reduction and delay instability are outlined. Viscous pressure bulge tests are conducted, and the experimental results of bulged shapes, thickness uniformity, polar strains, and instability behaviors validate the theories. The fracture strain under the non-uniform pressure condition shows a 5.6% increase compared with the uniform pressure condition. This study proves that non-uniform pressure can promote sheet formability, suggesting promising applications in sheet metal forming. [ABSTRACT FROM AUTHOR]

The hot compression experiments were performed at a deformation temperature of 720 °C to 870 °C and a strain rate of 0.0005 s−1 to 5 s−1. The strain‐compensated Arrhenius constitutive equation and the hot processing map at a strain of 0.6 were established, and the dynamic recrystallization behaviors of the alloy in different power dissipation (η) regions were studied. The results show that the correlation coefficient (R) and average relative errors (AARE) of the established constitutive equations are 0.999 % and 2.523 % in the β phase region, and 0.988 % and 7.709 % in the α+β phase region, respectively. The hot processing map shows that the deformation parameters in the high power dissipation regions range from 810 °C to 870 °C/0.0005 s−1 to 0.005 s−1, accompanied by a power dissipation factor of 0.41 to 0.55. These regions result from a combination of continuous and discontinuous recrystallization mechanisms. With the decrease in the power dissipation value, the appearance of deformation bands (DBs) and localized flow (FL) in the microstructure increased. [ABSTRACT FROM AUTHOR]

Mechanical metamaterials—structures with unusual properties that emerge from their internal architecture—that are designed to undergo large deformations typically exploit large internal rotations, and therefore, necessitate the incorporation of flexible hinges. Kirigami structures, made by introducing ordered cuts in a planar material, are one such example. In the mechanism limit, these structures consist of rigid bodies connected by ideal hinges that deform at zero energy cost. However, fabrication in this limit has remained elusive. Here, we demonstrate that the integration of textile hinges provides a scalable platform for creating large kirigami metamaterials with mechanism‐like behaviors. Further, leveraging recently introduced kinematic optimization tools, we show that textile hinges enable extreme shape‐morphing responses, paving the way for the next generation of mechanism‐based metamaterials. [ABSTRACT FROM AUTHOR]

Introduction Methods Results Conclusion Tracheal decellularization is one of the main processes to provide tracheal substitutes for tracheal replacement. Recently, studies have been held for agents and combinations of processes for tracheal decellularization with different outcomes. This study aimed to evaluate the efficacy of tracheal decellularization by the immunogenic cellular elements using residual deoxyribonucleic acid (DNA) contents (ng/mg) and the preservation of biomechanical integrity by glycosaminoglycan (GAG) content (μg/mg), modulus tensile strength (MPa), ultimate tensile strength (MPa), and stress loading of 50% deformation (N).We conducted a meta‐analysis based on PRISMA criteria. Data from experimental studies in MEDLINE, Scopus, and ScienceDirect from inception to August 21, 2023, were sought and computed using RevMan 5.4. The outcomes of tracheal decellularization were evaluated through effect size estimates based on pooled Standardized Mean Difference (SMD) with 95% CI.Tracheal decellularization has significantly reduced the DNA and GAG content after the process (SMD: −11.77, 95% CI [−13.92, −8.62], p < 0.00001; SMD: −6.70, 95% CI [−9.55, −3.85], p < 0.00001). No significant outcomes were observed in modulus and ultimate tensile strength result (SMD: −0.14, 95% CI [−0.64, 0.36], p = 0.58; SMD: 0.11, 95% CI [−0.57, 0.80], p = 0.75). The stress loading of 50% deformation was observed to significantly lower (SMD: −1.61, 95% CI [−2.49, −0.72], p = 0.0004).Tracheal decellularization has been proven to effectively remove immunogenic cells. However, extracellular matrix integrity and biomechanical properties vary among different decellularization techniques, indicating a need for further refinement to achieve better preservation. [ABSTRACT FROM AUTHOR]