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In this article, we thoroughly analyze the effect of the single-tendon and antagonistic tendons actuation on the tension loss of multisegment tendon-driven continuum manipulators (TD-CMs) with irregular geometry. To this end, we propose a generic analytical modeling approach and an iterative algorithm that can solve the unknown correlation between the distributed friction force, tendons’ tension transmission loss, and planar deformation behavior of TD-CMs during tendons’ pulling and releasing phases. The proposed generic model solely relies on known input tendons’ tensions and does not require a priori knowledge of the manipulator’s shape and/or other experimental conditions. To investigate the influence of the actuation type on the tension loss and deformation behavior of TD-CMs, we fabricated two different TD-CMs and performed various simulation and experimental studies with the single-tendon and antagonistic tensions actuation. The obtained results indicate the importance of considering the effect of the distributed friction force and actuation type on the tension(s) loss of multisegment TD-CMs. Moreover, it clearly demonstrates the efficacy and accuracy of the proposed model in providing insights and understanding of tension transmission process in various types of actuations in multisegment TD-CMs with irregular geometry.

The emerging 4D printing techniques open new horizons for fabricating self-actuated deformable objects by combing strength of 3D printing and stimuli-responsive shape memory materials. This work focuses on designing self-actuated deformable solids for 4D printing such that a solid can be programmed into a temporary shape and later recovers to its original shape after heating. To avoid a high material cost, we choose a dual-material strategy that mixes an expensive thermo-responsive shape memory polymer (SMP) material with a common elastic material, % for fabricating objects, which however leads to undesired deformation at the shape programming stage. We model this shape programming process as two elastic models with different parameters linked by a median shape based on customizing a constitutive model of thermo-responsive SMPs. Taking this material modeling as a foundation, we formulate our design problem as a nonconvex optimization to find the distribution of SMP materials over the whole object as well as the median shape, and develop an efficient and parallelizable method to solve it. We show that our proposed approach is able to design self-actuated deformable objects that cannot be achieved by state of the art approaches, and demonstrate their usefulness with three example applications.

Many applications and contexts including materials science, metallurgy, and solid-state physics, are concerned with the study of the behavior of viscoelastic materials. In addition, any composite or complex construction containing embedded polymers exhibits viscoelastic behavior under static and dynamic stress conditions. Wide types of linear/nonlinear constitutive models have been proposed to define the viscoelastic deformation process of viscoelastic materials in order to explore their mechanical behavior. However, it has been shown that the constitutive relationship in the integer-order of stress-strain available in conventional viscoelastic models may fail in some types of situations and do not match well with empirical evidence. In this paper, a novel mathematical model is provided that uses Caputo-Fabrizio fractional-order derivatives to describe the viscoelastic phenomena and is consistent with thermodynamic principles. The Caputo-Fabrizio kernel has many features, such as nonlocality and non-singularity in addition to the exponential form. The suggested model is used to study the dynamic reactions of an unbounded body with a spherical cavity made of viscoelastic material subjected to time-varying heat. Using the Laplace transform technique, numerical calculations of many physical fields are obtained and explored in depth.

The purpose of this paper is to present a shape preserving topology optimization method to prevent the adverse effects of the mechanical deformation on the Radar Cross Section (RCS). The optimization will suppress the variation of RCS on the perfect conductor surface by structural design. On the one hand, the physical optics method is utilized to calculate the structural RCS, which is based on the surface displacement field obtained from the finite element analysis of the structure. The corresponding design sensitivities of topology optimization are derived analytically and solved by the adjoint method. On the other hand, the RCS variation and mechanical performance are taken into account simultaneously by extending a standard compliance-based topology optimization model. Two optimization formulations are discussed in an illustrative example, where the influences of upper limits of the compliance and the RCS variation are considered. Two more examples are further tested to show the ability and validity of the proposed optimization method.

Although many soft robots, capable of crawling or climbing, have been well developed, integrating multimodal locomotion into a soft robot for transitioning between crawling and climbing still remains elusive. In this work, we present a class of inchworm-inspired multimodal soft crawling-climbing robots (SCCRs) that can achieve crawling, climbing, and transitioning between horizontal and vertical planes. Inspired by the inchworm’s multimodal locomotion, which depends on the “ $\Omega$ ” deformation of the body and controllable friction force of feet, we develop the SCCR by 1) three pneumatic artificial muscles based body designed to produce “ $\Omega$ ” deformation; 2) two negative pressure suckers adopted to generate controllable friction forces. Then a simplified kinematic model is developed to characterize the kinematic features of the SCCRs. Lastly, a control strategy is proposed to synchronously control the “ $\Omega$ ” deformation and sucker friction forces for multimodal locomotion. The experimental results demonstrate that the SCCR can move at a maximum speed of 21 mm/s (0.11 body length/s) on horizontal planes and 15 mm/s (0.079 body length/s) on vertical walls. Furthermore, the SCCR can work in confined spaces, carry a payload of 500 g (about 15 times the self-weight) on horizontal planes or 20 g on vertical walls, and move in aquatic environments.

To study the hot deformation behavior of Mg–8.3Gd–4.4Y–1.5Zn–0.8Mn (wt%) alloy, hot compression tests were conducted using a Gleeble–3500 thermal simulator at temperatures ranging from 653 to 773 K, true strain rates of 0.001–1 s−1, and a deformation degree of 60%. Results of hot compression experiments show that the flow stress of the alloy increases with the strain rate. The true stress–true strain curves are corrected by correcting the effect of temperature rise in the deformation process. Activation energy, Q, equal to 287380 J/mol and material constant, n, equal to 4.59 were calculated by fitting the true stress–true strain curves. Then, the constitutive equation was established and verified via finite element simulation. Results of the hot processing map show that the probability of material instability increases with the degree of deformation, which indicates that the material is not suitable for large deformation in a single pass. On the whole, the alloy is appropriate for multipass processing with small deformation and a suitable processing temperature and strain rate are 733 K and 0.01 s−1, respectively.

Clay brick masonry unit (CBMU) walls are widely used in building structures, and its damage and protection under explosion loads have been a matter of concern in the field of engineering protection. In this paper, a series of full-scale experiments of the response characteristics of 24 cm CMBU walls unreinforced and reinforced with polyurea elastomer subjected to blast loading were carried out. Through setting 5.0 kg TNT charges at different stand-off distances, the damage characteristics of masonry walls at different scaled distances were obtained. The reinforcement effect of different polyurea coating thicknesses and methods on the blast resistance performance of masonry walls under single and repeated loads were also explored. Five failure grades were summarized according to the dynamic response features of masonry walls. Based on the stress wave propagation pattern in multi-media composite structures, the internal stress distribution of masonry walls were analyzed, and the division basis of the masonry walls’ failure grades was then quantified. Combined with Scanning Electron Microscope(SEM) images, the deformation characteristics of soft and hard segments of polyurea and effects of detonation products on microstructures were revealed respectively, which provides an important reference for the design and application of polyurea in the blast resistance of clay brick masonry walls.

The landslides have an important influence on the force and deformation of existing tunnels, which may adversely affect the liner structures and even endanger normal operation. Current scholars have made few efforts to investigate the reinforcement measures for existing tunnels in the landslide region, and even paid less attention to probe into the pile-anchor strengthening mechanics. A new kind of pile-anchor strengthening system for existing tunnels has been proposed in this paper considering the influences of deforming landslides, in which the anti-slide pile, the anchor cable and the tunnel lining were integrated as one force whole. In order to observe the pile-anchor strengthening mechanics, three physical model tests for comparative analyses were established in case of the tunnel axis parallel to the sliding direction of landslide, including the conditions without reinforcements, only with anti-slide pile and full with the pile-anchor strengthening system. Specially for the pile-anchor strengthening model tests, the extra experimental evaluation for the interaction mechanics between existing tunnel and landslide was added, such as, the tunnel diameter of 40 and 50 mm and the pile-anchor of three and six pairs. In addition, three-dimensional numerical models were implemented to analyze the landslide deformation and the internal force of tunnels after installing the pile-anchor strengthening system. Comparing with non-reinforcement, the bending moment of tunnel and contact stress at interface between tunnel and landslide at the position of 200 m away from tunnel entrance with six pairs pile-anchor reinforcement dropped by 97.2% and 50%. The results show that the deformation of landslide, the bending moment of existing tunnel and the contact stress at the interface between tunnel and landslide pronouncedly diminish after taking the pile-anchor strengthening measures. The new combined pile-anchor system has higher bearing capacity and stability, which can further improve the operation safety of existing tunnels in landslide region.

The continental collision-induced far-field intraplate deformation may be topographically separated from or coherent with the collision front, the mechanism of which is poorly constrained. Here, we build a series of 2D thermo–mechanical models to explore the controlling factors of distal orogenesis in the framework of a composite terrane sandwiched between two strong continental blocks. The model results suggest that the development of distal orogenesis requires a strong rheological heterogeneity in the overriding lithosphere. Two types of far-field collisional effects with distinct patterns of topographic evolution are identified, characterized by (I) a delayed and discrete distal orogenesis separated from the collision front by a low-relief, less-deformed terrane interior, and (II) an instant distal orogenesis subsequently integrated into a progressively growing plateau. These two types of far-field orogenesis are revealed to be analogous to the development of the Kopet Dagh and northern Tibet. The comparisons between model results and geological observations provide significant constraints on the dynamics of crustal-scale deformation propagation and the formation of distinct lithospheric architectures.

Pre-driven longwall retracement roadway (PLRR) is commonly used in large mine shaft. The support crushing disasters occur frequently during the retracement, and roof management is necessary. Taking the 31107 panel as research background, the roof breaking structure of PLRR is analyzed. It is concluded that the roof cutting with vertical hydraulic fracture (HF) at a specified position, that is, fixed-length roof cutting, can reduce support load and keep immediate roof intact. The extended finite element method (XFEM) is applied to simulate hydraulic fracturing. The results show that both the axial and transverse hydraulic fracturing cannot effectively create vertical HFs. Therefore, a novel construction method of vertical HF based on the stress shadow effect (SSE) is proposed. The stress reversal region and HF orientation caused by the prefabricated hydraulic fracture (PF) are verified in simulation. The sub-vertical HFs are obtained between two PFs, the vertical extension range of which is much larger than that of directional hydraulic fracturing. The new construction method was used to determine the field plan for fixed-length roof cutting. The roof formed a stable suspended structure and deformation of the main PLRR was improved after hydraulic fracturing.

Objective: This study develops a biomedical ultrasound imaging method to infer microstructural information (i.e., tissue level) from imaging mechanical behavior of skeletal muscle (i.e., organ level). Methods: We first reviewed the constitutive model of skeletal muscle by regarding it as a transversely isotropic (TI) hyperelastic composite material, for which a theoretical formula was established among shear wave speed, deformation, and material parameters (MPs) using the acoustoelasticity theory. The formula was evaluated by finite element (FE) simulations and experimentally examined using ultrasound shear wave imaging (SWI) and strain imaging (SI) on in vivo passive biceps brachii muscles of two healthy volunteers. The imaging sequence included 1) generation of SW in multiple propagation directions while resting the muscle at an elbow angle of 90; 2) generation of SW propagating along the myofiber direction during continuous uniaxial muscle extension by passively changing the elbow angle from 90 to 120. Ultrasound-quantified SW speeds and muscle deformations were fitted by the theoretical formula to estimate MPs of in vivo passive muscle. Results: Estimated myofiber stiffness, stiffness ratio of myofiber to extracellular matrix (ECM), ECM volume ratio all agreed with literature findings. Conclusion: The proposed mathematical formula together with our in-house ultrasound imaging method enabled assessing microstructural material properties of in vivo passive skeletal muscle from organ-level mechanical behavior in an entirely noninvasive way. Significance: Noninvasive assessment of both micro and macro properties of in vivo skeletal muscle will advance our understanding of complex muscle dynamics and facilitate treatment and rehabilitation planning.

Nowadays, the demand for using jack-up platforms to carry out a large percentage of deep-water oil and gas exploration is steadily increasing. The response of jack-up platforms to the severe dynamic loads that may be encountered during the structure life is not examined enough. Therefore, this study attempts to investigate the response of jack-up platforms performance under the effect of dynamic loads due to wave, wind, earthquake and tsunami forces using the finite element method for two models with the lowest and highest hull elevations. The jack-up platform is located in the Gulf of Mexico. Earthquake accelerations are applied to the model in high and moderate seismic levels. In addition, tsunami waves are applied to the platform in three different directions at 0°, 45° and 90°. This study utilised Airy's linear wave approach to assess the surface elevations and wave kinematics. The reference wind velocity is 10 knots at 10 m over the mean water level. Results indicate that the dynamic response of the structure is affected by the height of the platform and by the increase of the platform hull elevation. The combination of the El-Centro earthquake, dead and live loads provides the major impact on the platform at the lowest (70 m) and highest (85 m) hull elevations. The comparison of all result proves that the jack-up platform hull under high earthquake intensity and tsunami waves with 45° has experienced maximum deformation. Moreover, raising the deck will increase the response of the dynamic load and displacements but will negatively affect the platform.

Soil arching and tensioned membrane effects are two main load transfer mechanisms for geosynthetic-reinforced pile-supported (GRPS) embankments over soft soils or voids. Evidences show that the tensioned membrane effect interacts with the soil arching effect. To investigate the soil arching evolution under different geosynthetic reinforcement stiffness and embankment height, a series of discrete element method (DEM) simulations of GRPS embankments were carried out based on physical model tests. The results indicate that the deformation pattern in the GRPS embankments changed from a concentric ellipse arch pattern to an equal settlement pattern with the increase of the embankment height. High stiffness geosynthetic hindered the development of soil arching and required more subsoil settlement to enable the development of maximum soil arching. However, soil arching in the GRPS embankments with low stiffness reinforcement degraded after reaching maximum soil arching. Appropriate stiffness reinforcement ensured the development and stability of maximum soil arching. According to the stress states on the pile top, a concentric ellipse soil arch model is proposed in this paper to describe the soil arching behavior in the GRPS embankments over voids. The predicted heights of soil arches and load efficacies on the piles agreed well with the DEM simulations and the test results from the literature.

Hall–Petch slope (k), an important parameter in Hall–Petch relation, describes the efficiency of strengthening effect by grain boundaries. Previously, a highly texture dependent k for Mg alloys is frequently reported, but, in the present study, we report a weak texture dependence of k in a rare-earth containing Mg-2Zn-1Gd plate with two peaks of (0002) poles inclining approximately ± 30° away from the ND toward the TD. Although there is a strong mechanical anisotropy between tension along the TD and RD, the k for TD-tension (280 MPa μm1/2) is quite similar to that for RD-tension (276 MPa μm1/2). Here, RD, TD and ND refer to the rolling direction, transverse direction and normal direction of the plate, respectively. The weak texture dependence of k is well predicted by the compound use of the activation stress difference between neighboring grains (ΔStress) and the geometric compatibility factor ( m ′ ). By analyzing how the texture affects the values for ΔStress and m ′ , the mechanism for this texture independence of k is ascribed to the activation of a high fraction of additional deformation mode, besides the predominant one for both RD-tension and TD-tension, namely, prismatic slip accompanied by a high fraction of basal slip for RD-tension and basal slip accompanied by a high fraction of prismatic slip for TD-tension. This will lead to multiple deformation transfer modes and, consequently, the effect of texture on the ease of deformation transfer across grain boundaries is weakened. As a result, there is a similar k for TD-tension and RD-tension.

This study focuses on the effect of lateral mass impact on ring-stiffened thin-walled cylindrical shell. Cylindrical shells were fabricated to validate the numerical modeling and analytical techniques, and drop tests were performed using a rigid spherical indenter. Next, stiffened-ring cylindrical shells with various structural size parameters were simulated using ABAQUS software. The relationships between the impact force, deformation displacement, and rebound velocity were established, on the basis of impact mechanics theory and simulation results. It derived fitting functions to analyse the relationship between the maximum load and maximum displacement of ring-stiffened cylindrical shell under dynamic mass impact. Based on the validation of the simulation model, the fitting function data were compared with the simulation results, and the functions showed a good accuracy. Besides, the parameters, mass ratio and stiffened-ring mass ratio were used to reflect the effect of the mass change in the ring-stiffened cylindrical shell. Furthermore, parametric studies on ring-stiffened cylindrical shell models were conducted to analyse the progressive impact responses.

The propagating margins of igneous sills (and other sheet intrusions) may divide into laterally and/or vertically separated sections, which later inflate and coalesce. These components elongate parallel to and thus record the magma flow direction, and they can form either due to fracture segmentation (i.e., “segments”) or brittle and/or non-brittle deformation of the host rock (i.e., “magma fingers”). Seismic reflection data can image entire sills or sill-complexes in 3-D, and their resolution is often sufficient to allow us to identify these distinct elongate components and thereby map magma flow patterns over entire intrusion networks. However, seismic resolution is limited, so we typically cannot discern the centimeter- to meter-scale host rock deformation structures that would allow the origin of these components to be interpreted. Here, we introduce a new term that defines the components (i.e., “elements”) of sheet-like igneous intrusions without linking their description to emplacement mechanisms. Using 3-D seismic reflection data from offshore NW Australia, we quantify the 3-D geometry of these elements and their connectors within two sills and discuss how their shape may relate to emplacement processes. Based on seismic attribute analyses and our measurements of their 3-D geometry, we conclude that the mapped elements likely formed through non-elastic-brittle and/or non-brittle deformation ahead of the advancing sill tip, which implies they are magma fingers. We show that thickness varies across sills, and across distinct elements, which we infer to represent flow localization and subsequent thickening of restricted areas. The quantification of element geometries is useful for comparisons between different subsurface and field-based data sets that span a range of host rock types and tectonic settings. This, in turn, facilitates the testing of magma emplacement mechanisms and predictions from numerical and physical analogue experiments.

In this article, pre-assembly hot-press pressure and thermal expansion effects in gas-diffusion layers (GDLs) are addressed to explore the practicalities of the constitutive model reported in the companion article. A facile technique is proposed to include deformation history dependent residual strain effects. The model is implemented in the numerical environment and compared with widely followed conventional models such as isotropic and orthotropic material models. With the normal and accelerated thermal expansion effects no significant variation in stresses or strains is reported with the compressible GDL model in contrast to the conventional incompressible form of the GDL model. The present work identifies the critical differences with advanced and extended variants of the model along with conventional GDL material models in terms of planar stress/strain distribution and the membrane response. Finally, the model is simulated for micro-cyclic stress loads of varying amplitudes that imitate the real working conditions of fuel cell. The inelastic energy dissipation in GDLs is predicted using the proposed model, which is utilized further to distinguish the safe (elastic) and unsafe (inelastic shakedown) operating limits. The inelastic collapse of GDLs is shown to be a active function of high amplitude micro-cyclic load with high initial clamping load.

The problem as to whether an inclusion when embedded in an elastic infinite matrix with a perfectly bonded interface could achieve uniform internal stress has been studied extensively in the literature. It has been shown that in almost all cases ellipsoidal shape (including elliptical shape for two-dimensional deformation) is the only inclusion shape ensuring the uniformity of the stress inside the inclusion if the external loading exerted remotely on the edge of the matrix is uniform. From a practical point of view, this result remains valid for a non-uniform remote loading imposed on the matrix provided the product of the inclusion's size and the gradient of the non-uniform loading is small enough (as compared with the overall level of the stress field induced by the non-uniform loading at the inclusion's position). In this paper, we explore the possibility of designing an inclusion enclosing uniform internal stress in an elastic infinite plane under anti-plane shear deformation for a non-uniform remote loading with arbitrary gradients. We derive the equations with respect to the parameters describing the configuration of the inclusion leading to a uniform internal stress inside the inclusion for a general polynomial remote loading, and establish the analytic and numerical solutions for the shape of the inclusion which are illustrated via several examples.

Drying of fine hair and fibers induces dramatic capillary-driven deformation, with important implications on natural phenomena and industrial processes. We recently observed peculiar self-assembly of hair bundles into various distinct patterns depending on the interplay between the bundle length and the liquid drain rate. Here, we propose a mechanism for this pattern selection, and derive and validate theoretical scaling laws for the polymorphic self-assembly of polygonal hair bundles. Experiments are performed by submerging the bundles into a liquid bath, then draining down the liquid. Depending on the interplay between the drain rates and the length of the fibers, we observe the bundles morphing into stars (having concave sides), polygons (having straight edges and rounded corners), or circles. The mechanism of self-assembly at the high drain regime is governed by two sequential stages. In the first stage of the high drain rate regime, the liquid covers the outside of the bundles, and drainage from inside the bundle does not play a role in the self-assembly due to the high viscous stress. The local pressure at the corners of the wet bundles compresses the fibers inward blunting the corners, and the internal lubrication facilitates fiber rearrangement. In the second stage, the liquid is slowly draining from within the fiber spacing, and the negative capillary pressure at the perimeter causes the fibers to tightly pack. In the slow drainage regime, the first stage is absent, and the fibers slowly aggregate without initial dynamic rearrangement. Understanding the mechanism of dynamic elastocapillarity offers insights for studying the complicated physics of wet granular drying.

Addendum variation effects on the Short Carbon Fiber (SCF) reinforced Polyamide66 (PA66) composite spur gear. By using percentage variations of 00,10,20,30,40,50,60 by weight of SCF in PA66. The addendum variation coefficients are considered in steps from a lower negative value to a higher positive value. The lower limit value is called an undercutting limit, and the higher value is called a peaking limit. Different addendum variation values of −0.4, −0.2, 0, +0.2 and + 0.4 mm and different percentage of SCF in PA 66. The performance parameters of spur gears like total deformation, Von-Mises, maximum principle, shear stress, and factor of safety are evaluated by using FEM analysis. The results show that when the addendum decreases, Von-Mises, maximum principal stress decrease, and total deformation, Shear stress, FOS increases. When the addendum increases, Von-Mises, shear stress, FOS decreases, and total deformation, maximum principal stress increases. Maximum principal stresses at the gear root on the tensile side were used to assess the bending strength of the gear. High deformation causes high shear stresses and is useful for the selection of gear material of particular applications. Based on the analysis results, Von-Mises stress and cyclic loading were instrumental in predicting deformation and gear failure.

The influence of surface roughness on the interfacial dynamic recrystallization kinetics and mechanical properties of Ti-6Al-3Nb-2Zr-1Mo hot-compression bonding joints was systematically investigated. It is found that for the bonding interface of rough surfaces, elongated fine grains are formed at the bonding interface due to shear deformation of the interfacial area. As the surface roughness increases, the proportion of elongated grains drastically decreases as they further reorient to form equiaxed grains along the bonding interface of rougher surfaces resulting from severe incompatible deformation of the interface area. Meanwhile, high-density geometrically necessary dislocations accumulate around the interfacial recrystallization area to accommodate the incompatible strain and lattice rotation. A rotational dynamic recrystallization mechanism is thereby proposed to rationalize the formation of fine interfacial recrystallization grains during bonding of rough surfaces. In contrast to that of rough surfaces, bonding interface of polished surfaces exists in the form of straight interface grain boundaries without fine grains under the same deformation conditions. While with the increase of deformation strain, small grain nuclei form along the bonding interface, which is associated with discontinuous dynamic recrystallization assisted by strain-induced boundary migration of interface grain boundaries. Moreover, the bonding joints of rough surfaces show lower elongation compared with that of polished surfaces. This is because the formation of heterogeneous fine grains with low Schmid factor along the bonding interface of rough surfaces, leading to worse compatible deformation capability and thereby poor ductility of bonding joints.

R-factor (Response reduction factor) is an important design consideration in seismic design of structures, which is assumed to consider energy dissipation of structures by means of ductility. So, proper estimation of R-factor is required for seismic design of structures which will account for ductile deformation so that suitable detailing of reinforcement can be done. In case of irregular structures, where the torsion effect is the predominant factor, accurate estimation of R-factor is even more difficult. Therefore, in the present study, an attempt has been taken to determine R-factor for plan irregular buildings. A G +7 storied building is considered and irregularity effect has been incorporated by C and L-shaped configuration. The design of the buildings has been done following Indian Standards. Modeling and analysis have been done using SAP2000. Plastic hinges have been considered to represent material nonlinearity. Mander’s confinement model has been considered. Nonlinear Static (Pushover) following FEMA 440 methods with uniform lateral load variations has been done. Initial tangent stiffness has been followed in equal area method during bi-linearization of pushover curve. It can be stated that apart from material strength and geometrical configuration, performance requirement of the buildings is the most important factor for selection of R-factor.

Centrifuge model tests on slopes subject to shaking and rainfall have been performed to examine the response of slopes with shaking-induced cracks to subsequent rainfall and evaluate the corresponding landslide-triggering mechanisms. The failure pattern of the slope subject to shaking and then rainfall was found different from that of the slope subject to only rainfall. When shaking caused cracks on the slope shoulder and rupture line below, the mobilized soil slid along the slip surface that extended to the rupture line, the main crack became the crown of the undisturbed ground once the slope was subject to a subsequent rain event, and the progression of the landslide was related to the rainfall intensity. During the landslide caused by light rainfall, the main scarp kept exposing itself in the vertically downward direction while the ground behind the main crack in the crack-containing slope remained undisturbed. The detrimental effect of cracks on soil displacement was more evident when the slope was exposed to heavy post-shaking rainfall, resulting in a rapid and massive landslide. Additionally, the volume of displaced material of the landslide, the main scarp area on the upper edge, and the zone of accumulation were larger in the crack-containing slope subject to heavy rainfall, in comparison with those in the crack-free slope. The deformation pattern of slopes with shaking-induced cracks during rainfall was closely related to rainfall intensity and the factor of safety provided a preliminary estimation of slope stability during rainfall. Moreover, even when subjected to the same rainfall, the slopes with antecedent shaking-induced cracks displayed different levels of deformation. The slope that experienced larger shaking had greater deformation under the following rainfall, and the shaking-induced slope deformation also controlled the slip surface location. Finally, the velocity of rainfall-induced landslide could be greatly influenced by the prior shaking event alone. Despite being under light rainfall, the slope that has encountered intense previous shaking exhibited an instant landslide.

The concrete-faced rockfill dam (CFRD) is one of the widely constructed dam types, the concrete slab is the key anti-seepage structure of CFRD, and its safety directly affects the safety of the dam. In view of the traditional reliability analysis methods are complicated to calculate and cannot assess concrete slab cracking risk in real-time. In this paper, through the analysis of the response mechanism of slab stress and dam deformation, the coupling relationship between the reliability of concrete slab and monitoring data is revealed. Considering the randomness of the material parameters of CFRD, the limit state functions of concrete slab cracking are established by the response surface method (RSM). The accurate numerical simulation of the construction and operation process of CFRD is realized through the back analysis, then the time-variant reliability calculation of the concrete slab is realized. By analyzing the correlation between concrete slab reliability and some key factors such as dam displacement, water level, and time, a coupled evaluation model of reliability and monitoring data is proposed. Houziyan CFRD is selected as an example, the engineering application shows that the simulation relative error by using this coupled evaluation model is less than 5.0%, this model has the advantages of high efficiency, good precision, and strong applicability. The real-time reliability analysis of the concrete slab is realized and a new method for prediction and early warning of concrete slab cracking of CFRDs is provided.

Research and development of biocomposites for Unmanned Aerial Vehicle (UAV) structures have become relevant throughout the last decade, due to their cost and lightweight accompanied with good mechanical properties. Moreover, Blended Wing Body configurations (BWB) have aroused special interest, because of their aerodynamic efficiency, manufacturing simplicity and increased fuel economy. In this context, the present study investigates the strength distribution in a semi-monocoque structure of a blended wing body UAV using a composite material based on pre-load jute fibers. For this aim, a three-dimensional numerical simulation with a unidirectional fluid–solid coupling is implemented in a steady analysis at cruise conditions. The air pressure distribution is calculated using computational fluids dynamics (CFD), which then incorporates the aerodynamic loads within the structural module and using finite element method (FEM) determines the static stress distribution and deformation. The properties and manufacturing characteristics of jute-based composite material used in the numerical analysis were incorporated in the analysis and the numerical model was validated against experimental data. Based on the comparison between the structure built by pre-load jute fibers-based composite material and EPO foam, the results show that the proposed material reduces the deformation in 65% and performs better mechanically.

While perception of high-viscosity solutions (η>1000cP) is speculated to be linked to filiform papillae deformation, this has not been demonstrated psychophysically. Presently, just-noticeable-viscosity-difference thresholds were determined using the forced-choice staircase method and high-viscosity solutions (η=4798–12260cP) with the hypotheses that the tongue would be chiefly responsible for viscosity perception in the oral cavity, and that individuals with more, longer, narrower filiform papillae would show a greater acuity for viscosity perception. Subjects (n=59) evaluated solutions in a normal, “unblocked” condition as well as in a “palate blocked” condition which isolated the tongue so that only perceptual mechanisms on the lingual tissue were engaged. Optical profiling was used to characterize papillary length, diameter, and density in tongue biopsies of a subset (n=45) of participants. Finally, psychophysical and anatomical data were used to generate a novel model of the tongue surface as porous media to predict papillary deformation as a strain-detector for viscosity perception. Results suggest that viscosity thresholds are governed by filiform papillae features. Indeed, anatomical characterization of filiform papillae suggests sensitivity to high-viscosity solutions is associated with filiform papillae length and density (r=0.68, p

International audience; This paper analyzes the compaction behavior of assemblies composed of soft (elastic) spherical particles beyond the jammed state, using three-dimensional non-smooth contact dynamic simulations. The assemblies of particles are characterized using the evolution of the packing fraction, the coordination number, and the von Misses stress distribution within the particles as the confining stress increases. The packing fraction increases and tends toward a maximum value close to 1, and the mean coordination number increases as a square root of the packing fraction. As the confining stress increases, a transition is observed from a granular-like material with exponential tails of the shear stress distributions to a continuous-like material characterized by Gaussian-like distributions of the shear stresses. We develop an equation that describes the evolution of the packing fraction as a function of the applied pressure. This equation, based on the micromechanical expression of the granular stress tensor, the limit of the Hertz contact law for small deformation, and the power-law relation between the packing fraction and the coordination of the particles, provides good predictions from the jamming point up to very high densities without the need for tuning any parameters.

This paper presents a new contact boundary condition for finite volume simulations of frictional contact problems involving geometrical and material non-linearities. Deformation of bodies in contact is described by the updated Lagrangian form of the momentum equation which is discretised in space using the cell-centred finite volume method. The proposed contact boundary condition is based on the finite volume implementation of the penalty based segment-to-segment contact force calculation method in which normal contact pressure, governed by a penalty law, is integrated across the discretised contact surface, enforcing contact constraints in an integral manner. Such an approach, as opposed to the pointwise contact force calculation algorithm, allows for more accurate and more robust treatment of the contact area edge, simultaneous calculation of contact forces on both contact surfaces as well as smoother contact force during large sliding. The proposed numerical method is tested on challenging mechanical contact problems showing very good agreement with the available benchmark results.

Biomimicry can be termed as the concept that involves the imitation of models, systems and elements of the nature to solve complex human problems. When compared to the conventional techniques, it is an efficient, innovative and sustainable way and thus has scope in future. The various levels in biomimicry are utilized in the construction of the structures inspired from the nature thus paving way to innovation and sustainability. Various information can be learnt from nature when it comes to solving our challenges in a sustainable way. Nature builds to shape, because shape is cost effective and it minimizes the expenditure on materials while maximizing the effectiveness to achieve the desired functions. In this study the analysis of the conventional pin jointed plane frame is done first using STAAD. Pro to identify the compression and tension members in the frame. The various conventional frame models are modelled and analyzed. The finite element analysis is done using ANSYS 2020R2. A conventional pin jointed plane frame of height 4 m, bay width 4 m and strut length of 5.66 m were analyzed to know its member properties. A conventional pin jointed frame with horizontal springs provided at both the sides of the frame was modelled and analyzed. The optimized mimicked members are assembled to form the mimicked frame and analyzed. The various parameters such as total deformation, directional deformation, normal stress, equivalent stress, maximum principal stress and minimum principal stress were compared for the pin jointed plane frames. The present study helps in the reduction of material usage and self-weight of elements thus resulting in a sustainable and efficient structure

Knitting is an effective technique for producing complex three-dimensional surfaces owing to the inherent flexibility of interlooped yarns and recent advances in manufacturing providing better control of local stitch patterns. Fully yarn-level modelling of large-scale knitted membranes is not feasible. Therefore, we use a two-scale homogenisation approach and model the membrane as a Kirchhoff-Love shell on the macroscale and as Euler-Bernoulli rods on the microscale. The governing equations for both the shell and the rod are discretised with cubic B-spline basis functions. For homogenisation we consider only the in-plane response of the membrane. The solution of the nonlinear microscale problem requires a significant amount of time due to the large deformations and the enforcement of contact constraints, rendering conventional online computational homogenisation approaches infeasible. To sidestep this problem, we use a pre-trained statistical Gaussian Process Regression (GPR) model to map the macroscale deformations to macroscale stresses. During the offline learning phase, the GPR model is trained by solving the microscale problem for a sufficiently rich set of deformation states obtained by either uniform or Sobol sampling. The trained GPR model encodes the nonlinearities and anisotropies present in the microscale and serves as a material model for the membrane response of the macroscale shell. The bending response can be chosen in dependence of the mesh size to penalise the fine out-of-plane wrinkling of the membrane. After verifying and validating the different components of the proposed approach, we introduce several examples involving membranes subjected to tension and shear to demonstrate its versatility and good performance., 24 pages, 14 figures

The article presents a brief overview of the life path of the Swiss mathematician and mechanic Leonard Euler, considers the history of the emergence of the formula for calculating stability, shows options for taking into account the fl exibility of an element in the calculations of reinforced concrete structures, the disadvantages of the Euler curve and the features of its application in relation to structures made of high-strength concrete and concrete hardening under pressure. An example of the result of using a non-linear deformation model in the calculations of eccentrically compressed reinforced concrete elements with the introduction into the algorithm for calculating a coeffi cient that takes into account the eff ect of buckling (defl ection) of an element on its bearing capacity is given.

Many materials demonstrate a dependence of mechanical properties on the type of stressed or deformed states. This is most noticeable in the dependence of the processes of shear and bulk deformation. Such materials include rocks, structural graphite, concrete, some grades of steel, cast iron, and aluminum. The main properties of these materials are an absence of a "single curve" relationship between the intensity of stresses and the intensity of deformations. Under shear conditions, bulk deformations can occur. Such materials can be described by constitutive equations that depend on the parameter of the type of a stress state, which is the ratio of the first invariant of the stress tensor to the stress intensity. Thus, these defining relations give the dependence of the strain tensor components on the stress tensor components. Such defining relations can be quite cumbersome, and therefore do not allow an analytical treatment to obtain defining relations that give the dependence of the components of the stress tensor on the components of the strain tensor. The paper proposes the constitutive relations obtained from the analysis of test results of various materials, which properties depend on the type of deformed state. Conditions are derived for material constants that ensure the uniqueness of the solution of boundary value problems. Based on experimental data obtained under the conditions of the proportional loading of various rocks: limestone and talcochlorite, as well as the results of mechanical tests of several grades of concrete, the constants of the mathematical model are determined. The results of the experimental studies are compared with theoretical dependencies predicted by the model. The limited applicability of the proposed constitutive relations is established.

Rock masses with remarked rock structure are likely to be highly anisotropic; thus, the relative orientation of the tunnel with respect to the rock structure will affect the tunnel behavior. Displacements measured at the walls of tunnels in highly anisotropic rock masses often reveal an asymmetric deformation pattern around the tunnel perimeter, which is often interpreted as the result of rock heterogeneity or changing geology. However, numerical and analytical investigation of tunnels in anisotropic rock masses show that the tunnel axis misalignment with the principal directions of stress and material anisotropy induce anti-symmetric axial displacements (i.e., axial distortion of the tunnel cross section) far behind the tunnel face. Near the face, the axial distortion is partially constrained, causing asymmetric radial displacements. In this study, tunnels excavated with and against dip of the major rock mass discontinuity are explored using 3D FEM modeling. A detailed analysis on the mechanisms associated with the direction of excavation is provided. It is shown that the asymmetric displacements near the face may strongly affect the displacements measured at the tunnel walls, which may explain the asymmetric displacements commonly observed on tunnels in anisotropic rock.

The dominant structural systems used for high-rise buildings are tube-type systems. Tall tube-type structures act as a cantilever box girder and become prone to the shear lag phenomenon. This phenomenon causes nonlinear stress along the side of the tubular structures, while the beam theory assumes the stress to be linear. This mechanism reduces the efficiency of tube-type structural systems to resist lateral loads. This study explains a detailed discussion of the shear lag effect and the cause of its existence in two cases, positive and negative, through simple numerical analyses. To this end, the impact of lateral deformation on the shear lag effect was investigated in three tube-type structural systems: framed tube, diagrid, and hexagrid with different heights of 50-, 80-, and 110- story buildings subjected to wind load. The lateral deformation of the model structures was compared with the planer deformation (shear and bending deformation) of the cantilever box girder as the benched mark. Analysis results illustrated that the tube type structural system configuration affected the shear and bending deformation portions and the shear lag effect. Based on the results, the direction of the shear flow was changed according to the slope direction of the tangent line of the deflection curve (first deviation) and caused two cases, positive and negative ones. From the numerical results of candidate models, when the tangent line's angle became zero, the shear lag became minimum. When the curvature of the deflection curve (second deviation) was changed (upward into inward), the shear lag became maximum.

Total Lagrangian - Smoothed Particle Hydrodynamics (TL-SPH) is a classical algorithm to improve the tensile instability encountered in the conventional Eulerian kernel-based SPH method for solid mechanics. Meanwhile, the gradient correction usually is employed in TL-SPH to enhance the consistency of approximation, which would generate unavoidable time costs. Therefore, a simplified gradient correction under the initial configuration is derived. Aiming at different particle configurations, the corresponding selection modes are provided and verified. Then the simplified gradient correction is introduced into TL-SPH, which is the Improved TL-SPH (ITL-SPH) method. Firstly, a classical example – elastic rubber collision is simulated to verify ITL-SPH has the same ability as TL-SPH to improve tensile instability. Then, the convergence and high efficiency of ITL-SPH is demonstrated via the uniaxial tension of a plate. Moreover, the plate with square and triangle holes also is simulated to show the adaptation and stability of ITL-SPH for the extreme boundary. Under the Total Lagrangian frame, the treatment to model the crack is necessary. So, this paper proposes a damage model and combines it with the ITL-SPH method for crack initiation and propagation, which is verified by the plate with holes and the notched beam examples.

The deformation capacity of a viscoelastic damper (VED) is generally limited by the thickness of the VE pad. In this study, a VED with fail-safe mechanism was developed and its seismic performance was evaluated by a series of experiments of full-scale two-story reinforced concrete (RC) frame before and after seismic retrofit. The VED is composed of high damping rubber viscoelastic pads and is installed vertically between stories. One bare frame and two retrofitted frames with different damper capacities were tested under cyclic loads to validate the effectiveness of the newly developed dampers. The Bouc Wen model was developed to simulate the seismic behavior of the damper, which turned out to represent the behavior of the VED accurately. As a case study, the proposed VED was applied to seismic retrofit design of a 4-story RC moment framed structure, and it was found that the proposed retrofit scheme could adequately improve the seismic performance of the structure by reducing both inter-story and residual displacements.

In the light of the shortcomings of the calculation method for the diagonal crack width, a new method based on the bond-slip theory is proposed. In view of it is difficult to measure the external load or to predict the crack width accurately in actual earthquake scenario, it is difficult to evaluate the damage degree of seismic-damage column, the width calculation method of transverse cracks and diagonal cracks based on the flexural deformation and shear deformation is established. On this basis, a method and process for calculating the maximum crack width based on the horizontal displacement of the seismic-damaged RC column is proposed, and the analytical solution of the damage index of the RC column based on the crack width is obtained. The analysis of an example proves that the new method can be used to accurately calculate the crack width based on the horizontal displacement of the RC column, and the dynamic evolution process of the crack width and its failure mode can be revealed. In addition, the example analysis also proves that the damage value of the RC column obtained from the analytical solution of the damage index is reasonable and credible. This study can provide strong support for the rapid assessment of the seismic-damaged RC columns.

A constitutive model that explicitly considers the gradual recruitment of collagen fibers is applied to investigate the uniaxial properties of human ascending aortic aneurysms. The model uses an effective stretch, which is a continuum scale kinematic variable measuring the true stretch of the tissue, to formulate the fiber stress. The constitutive equation contains two shape parameters characterizing the stochastic distribution of fiber waviness, and two elastic parameters accounting for, respectively, the elastic properties of ground substance and the straightened collagen fibers. The model is applied to 156 sets of uniaxial stress-stretch data obtained from 52 aneurysm samples. Major findings include (1) the uniaxial response can be well described by a quadratic strain energy function of the effective strain; (2) the ultimate stretches, when measured in terms of the effective stretch, are closely clustered around 1.1, in contrast to a much wider range in the original stretch; and (3) the ultimate stress correlates positively with the fiber stiffness. The age dependence and directional differences of constitutive parameters are also investigated. Results indicate that only the waviness depends strongly on age; no clear alterations occur in elastic parameters. Further, the fibers are wavier and stiffer in the circumferential direction than in the longitudinal direction. No other parameters exhibit significant direction difference. STATEMENT OF SIGNIFICANCE: We introduced a constitutive model which explicitly accounts for collagen fiber recruitment to investigate the uniaxial properties of human ascending aortic aneurysm tissues. Uniaxial response data from 156 specimens were considered in the study. It was found that the seemingly dissimilar response curves are, in fact, similar if we measure the deformation using an effective stretch which factors out the uncrimping deformation. The rupture stretches in terms of the effective stretch are closely packed around 1.1. And the stress-stretch curves collapse to a canonical curve after a transformation.

The average shear-bearing ratio (β) of buckling restrained brace (BRB) is a key parameter, affecting the seismic performance of buckling restrained braced steel frames (BRBF). In order to determine the dynamic response of multi-story BRBF with different β values, two kinds of structural models are established, one is with the rigid connection of beam-column joints, and the other model has both hinged and rigid joints. The nonlinear time-history analysis of multi-story BRBF structures are carried out by selecting the seismic waves with predominant period close to the first mode period of each research model, and the seismic waves that are significantly different from it. The influence of β on the shear displacement, bending displacement and vibration mode of the structure are revealed: when β ≤ 30%, the story drift of multi-story BRBF structure is mainly shear deformation and the first vibration mode is predominant. When β increases, the bending deformation of the story drift increases. The second vibration mode of the structure is predominant when β ≈ 90%. It is suggested that the equivalent seismic force of multi-story BRBF structure with β > 30% should not be calculated by the base shear force method.

Large earthquakes in the Tibetan Plateau generally occur on block-boundary faults and produce coseismic surface ruptures that indicate the sense of block movement. However, seismic hazard in the block is less concerned. The Mw 7.3 Maduo earthquake on 22 May 2021 hit the internal Bayan Har block, which provides a rare opportunity to study the deformation features of the intra-block tectonics in central Tibet and related kinematics implications. We developed the high-resolution survey via the DJI drone of Phantom 4 Pro RTK and detailed field observations, to sum up the typical characteristics of the Maduo coseismic surface rupture zone. Then we classified these surface ruptures based on rupture orientation, spatial distribution, and stress state and analyzed their kinematic mechanisms. Our results indicate that (1) the typical surface ruptures of the Maduo earthquake are shear fractures, tensional cracks, and mole tracks, which follow the Riedel shear model; (2) the Riedel shear structures reveal a sinistral strike-slip movement sense for the seismogenic fault, accordant with regional tectonics; (3) seismic potential on minor faults in the interior block should be emphasized highly. This study will not provide insights into the kinematics of surface ruptures on a strike-slip fault but will strengthen the understanding of seismic hazards on an intra-block active fault.

A new type of the y-shaped (Y) bracing system composed of three brace members arranged in a y-shaped geometry, frictional mechanism for energy dissipation and pre-compressed axial springs to provide the self-centering capability is developed and studied in this paper. To improve the seismic performance of the self-centered y-shaped (SCY) braced frame, it is designed such that the structural steel members including beam, columns and braces other than the self-centering member remain within the elastic range of steel material leading to protect the structural elements from damages under lateral loading. The mechanics of this system are explained, the equations governing its hysteretic responses are outlined and scaled validation tests of two frames with different geometries are conducted under the condition of reversed cycles of loading. The results of the two tested frames under the quasi static loading show that the SCY braced frame has stable hysteretic loops which ensure a constant level of energy dissipation. Analytical findings which were verified by the results of the experimental tests show that increasing the length of the self-centering element increases the force capacity of the SCY braced frame and the self-centering element experiences the greatest deformation under lateral loading in a specific length and angle.

Multiple ballistic impacts are carried out on a 2024-T4 aluminum alloy by spherical steel projectiles (5-mm diameter) at ∼ 400 m s − 1 , to investigate its dynamic deformation and damage. The ballistic impact process is captured with high-speed photography. Postmortem samples are characterized with optical imaging, three-dimensional laser scanning, microhardness testing and electron backscatter diffraction. With increasing number of impacts, crater diameter increases slightly, but crater depth and crater volume increase significantly, and strain accumulation leads to microhardness increase overall. Crater parameters all follow power-law relations with the number of impacts. Twin-like deformation bands and macroscopic deformation twins are produced by impact as a result of spontaneous dislocation self-pinning under high strain rate, large shear deformation. Under multiple impacts, shear strain accumulation in the arc-shaped region of the crater induces deformation twinning when it exceeds a critical value ( ∼ 1.1 − 1.6 ). It is highly possible that the deformation twins are related to deformation bands, since they both share one set of the { 111 } pole with the initial matrix grain. A finite element method model is optimized to reproduce experimental observations and interpret deformation mechanisms.

Recently, we corrected the Green's functions for holes/cracks in composite laminates under coupled stretching-bending deformation. Through these corrected Green's functions, the fundamental solutions required for the special boundary element of holes/cracks in composite laminates are derived. By the use of dual coordinates, the derived fundamental solutions can be further applied to the cases of inclined holes and cracks. Moreover, a formula evaluating the stress intensity factors by using boundary nodal displacements and tractions is derived. With these closed-form solutions, the special boundary element developed in this study can deal with various kinds of hole/crack problems in composite laminates. Their loads can be in-plane tension, compression, or shearing, out-of-plane force, bending or twisting, distributed or concentrated, on the surfaces or along the edges; their boundaries can be simply supported, clamped, or free edges; their defects can be a hole or a crack with horizontal or inclined orientation; their laminates can be symmetric or unsymmetric. No matter which kind of conditions, no meshes are required on the hole and crack surfaces. And the stress intensity factors of cracks can be calculated directly without requiring any meshes along the crack surfaces or near the crack tip.

In this study we test whether principal components of the strain rate and stress tensors align within Switzerland. We find that 1) Helvetic Nappes line (HNL) is the relevant tectonic boundary to define different domains of crustal stress/surface strain rates orientations and 2) orientations of T- axes (of moment tensor solutions) and long-term asthenosphere cumulative finite strain (from SKS shear wave splitting) are consistent at the scale of the Alpine arc in Switzerland. At a more local scale, we find that seismic activity and surface deformation are in agreement but in three regions (Basel, Swiss Jura and Ticino); possibly because of the low levels of deformation and/or seismicity. In the Basel area, deep seismicity exists while surface deformation is absent. In the Ticino and the Swiss Jura, where seismic activity is close to absent, surface deformation is detected at a level of ~2 10E−8/yr (~6.3 10E−16/s)., Scientific Reports, 8, ISSN:2045-2322

An analytical approach is established to analyze the mechanical behavior of a unidirectional (UD) composite subjected to an in-plane shear. The effects of the interface debonding on the in-plane shear strength and plasticity of the composite are evaluated respectively. The volume-averaged internal stresses of the fiber and matrix are calculated through Bridging Model. Owing to the stress fluctuation in the matrix caused by other phases (such as the imbedded fiber and interface crack), the homogenized matrix stresses must be converted into true values based on a stress concentration factor (SCF). A new in-plane shear SCF of a composite with debonded interface is derived and applied to the predictions of strain and strength in this paper. Moreover, the contribution of the relative slippage between fiber and matrix to the non-linear shear deformation of the composite is analyzed. Finally, the efficiency and accuracy of our theory are verified with a series of examples. The approach is very efficient because the calculation can be achieved with explicit expressions mainly based on the constituent material properties. The comparisons between predicted strength and deformation with the experimental results show that our analytical approach can give out reliable underlying data for multi-scale analysis. Moreover, this theoretical method can tell if and how much the interface of a composite needs to be modified for a given load environment.

In order to study the instantaneous mechanical properties of rock mass discontinuities with different 3D morphologies during the shear process, the Brazilian splitting method is used to prepare natural rock mass discontinuities, and the high-precision 3D scanning test of discontinuities is carried out. The Z 2 is selected as the evaluation parameter of the discontinuities. Based on the graded cyclic shear test results of discontinuities, the influence of the morphology characteristics on the strength and deformation characteristics is analyzed. With the increase of shear times, the 3D morphology characteristic parameters of the structural plane decrease steadily after the graded cyclic shear. Based on the test curve, the graded cyclic shear characteristics of rock mass discontinuities are analyzed from the shear deformation, and the shear process of the discontinuities is finely divided by combining with the variation characteristics of shear stiffness. Combined with the 3D morphology parameters, an empirical formula for the shear strength of discontinuities is proposed. Through verification, the effect of the new model is better than that of the classical JRC-JCS model.

Detailed quasi-in-situ grain-by-grain slip trace analysis and EBSD analysis were performed on the as-extruded, under-aged, and peak-aged Mg–10Y (wt pct) sheets to investigate the precipitate effects on the individual slip activities and plastic heterogeneity during room temperature compression. The sheet exhibited a significant age-hardening response whose yield strength increased by 63 pct after the peak-aged treatment. In the as-extruded condition, deformation was dominated by pyramidal II $$\langle c + a\rangle$$ slip (42.3 pct) followed by basal $$\langle a\rangle$$ slip (31.0 pct) and then pyramidal I $$\langle c + a\rangle$$ slip (21.1 pct). After the peak-aged treatment, the frequency of basal $$\langle a\rangle$$ slip increased to ~ 70 pct, and the pyramidal I/II slips significantly decreased to ~ 20 pct, which indicates the precipitate strengthening on pyramidal $$\langle c + a\rangle$$ slips was significantly over basal $$\langle a\rangle$$ slip. Most activated slip systems (68.2 pct) exhibited large normalized Schmid factors ( $${m}_{\mathrm{nor}}$$ > 0.3), but substantial (18.2 pct) hard-oriented slip systems ( $${m}_{\mathrm{nor}}$$ < 0.1) were also activated, suggesting local stress deviation. The magnitude/distribution of intragranular misorientation angle and geometrically necessary dislocation (GND) density inside a grain cannot be correlated with the visibility of slip trace from a statistical viewpoint. The extremely high GND density near grain boundary (GB) was closely related to (i) significant disparity of max Schmid factors for a particular slip mode and/or (ii) high GB misorientation between adjacent grains.

The blade and disc's interface region (dovetail) is an integral part that plays an essential role in advanced flight machines. In this region, the major source of stress arising is the rotation of an engine shaft. Concerning this, geometry, material selection, and stress calculation need to perform at the predesign phase. This paper proposes four-directional braided ceramic matrix composites (CMCs) for the dovetail region because of its high transverse and shear strength, with less weight and thermal resistance. Due to the heterogeneous characteristics of proposed four-directional CMCs, homogenized mechanical properties are calculated for dovetail under non-isotropic conditions using multi-scale modeling and mechanics of structure genome method (MSG) for homogenization. After optimizing the dimensions for shape and minimizing the mass in the design study, the estimated homogenized mechanical properties are used to conduct a three-dimensional non-linear finite element (FE) analysis of the disc-dovetail assembly to check the feasibility of braided CMC’s dovetail over conventional dovetail. A comparative study between conventional and proposed dovetail material is made for the first time using the FE analysis results. Four-directional braided CMC (SiC/SiC) fits the blade disc interface region from a strength point of view because it shows less deformation, stress, and high stability than conventional Ti-alloy.

This research was carried out to understand the nature of strike-slip Jhelum Fault zone and to propose a model for the surface to subsurface deformation pattern. Field data along with satellite images are used to construct the geological map. Moreover, the subsurface model has been proposed using the mechanism of dip-isogons in computer application which connects points of equal inclination or dip on the outer and inner bounding surfaces of a folded layers. The proposed geological map and subsurface model shows that the Jhelum Fault when propagated in the south from Hazara-Kashmir Syntaxis forms a continuous shear zone on surface with some discontinuous exposure of splay faults rather than exposed as continuous discrete break. Likewise, the subsurface cross sections show that deformation along the fault zone is accumulated by splay faults from the main Jhelum Fault, which forms a positive flower structure with steep north-eastward dips, which is characteristics of strike-slip movement along Jhelum Fault Zone. The vertical stratigraphic throw along these faults shows small offsets and little east–west shortening, indicating that the major slip along the fault is strike slip.