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Soft materials are an important class of materials. They play critical roles both in nature, in the form of soft tissues, and in industrial applications. Quantifying their mechanical properties is an important part of understanding and predicting their behavior, and thus optimizing their use. However, there are often no agreed upon standards for how to do so. This also holds true for quantifying their fracture toughness; that is, their resistance to crack propagation. The goal of our work is to fill this knowledge gap using blood clot as a model material. In total, we compared three general approaches, some with multiple different implementations. The first approach is based on Griffith’s definition of the critical energy release rate. The second approach makes use of the J-Integral. The last approach uses cohesive zones. We applied these approaches to 12 pure shear experiments with notched samples (some approaches were supplemented with unnotched samples). Finally, we compared these approaches by their intra- and inter-approach variability, the complexity of their implementation, and their computational cost. Overall, we found that the simplest method was also the most consistent and the least costly one: the Griffith-based approach, as proposed by Rivlin and Thomas in 1953. [ABSTRACT FROM AUTHOR]

The Sonid Zuoqi ductile detachment zone is located at the southeastern margin of the Central Asian orogenic belt (CAOB), striking EW and dipping to the S. The major rock type of the Sonid Zuoqi ductile detachment zone is mylonite derived from granite. The sequence of mylonite features is: (1) S and C foliations of mylonite, and (2) extensional crenulation cleavage (ecc) or C' and the kinematic vorticity (Wk) value changed from 0.70 to 0.95 and from 0.37 to 0.69, respectively; the strain type of the mylonites within the Sonid Zuoqi ductile detachment zone is compressional to planar strain. The strong deformation mylonite and Halatu plutons yielded a zircon U‐Pb age of 244 Ma and a zircon (U‐Th)/He age of 214 Ma, respectively. Based on the strain and kinematic vorticity analysis, together with the zircon U‐Pb and zircon (U‐Th)/He ages and the regional tectonic background, the study area experienced three stage evolution: tangential simple‐shear (244 Ma), simple‐shear‐dominated general shear represented by upper crustal extension (224 Ma) and pure–shear–dominated general shear represented by the Halatu pluton doming (214 Ma), which constrained the early Mesozoic NE‐SW crustal extension at the southeastern margin of the CAOB. This NE‐SW extension probably originated from the post‐orogenic extensional collapse of the CAOB, subsequent exhumation being controlled by the far afield effects of the closure of the Mongol‐Okhotsk belt. [ABSTRACT FROM AUTHOR]

Concrete beam under pure shear load conditions The shear force capacity of reinforced concrete components is usually investigated experimentally by subjecting the test specimens to vertical loads. These loads induce internal forces in the form of bending moments and shear forces. However, these internal forces cannot be controlled independently under such loading conditions. This article presents a test set‐up that allows a constant bending moment and a constant shear force of any magnitude to be generated in reinforced concrete beams. The loading situation to generate a constant shear force in a beam with a rectangular cross‐section was realized in three component tests. In addition, an FEM model was developed for comparative calculations. The component tests showed a brittle failure. With regard to the load‐displacement behavior and the calculated load‐bearing capacities, there was good agreement between the component tests and the corresponding FEM simulations. The test setup presented here is generally considered suitable for generating a state of pure shear force in reinforced concrete beams. [ABSTRACT FROM AUTHOR]

Background: For an anisotropic thin-walled tube without changing its circular geometry, only the experimental data of initial yield and subsequent plastic deformation along the axial and circumferential directions can be obtained till now. These experimental data are not sufficient to construct an anisotropic constitutive relation for simulations of tube deformation processes. Objective: A novel shear test of tubular materials is proposed to achieve the state of shearing plastic deformation along the axial direction of thin-walled tubes. Methods: Two semi-circle mandrels and one specially designed tubular specimen are used in the shear experiment. Optimizations of the specimen shape and mandrel structure were carried out by using FE simulation. The influence of the specimen shape, such as the length of the shear zone and the length of the axial slot, on the stress state of the shear zone was discussed. A thin-walled 5052 aluminum tube was used in the shear experiment using the optimized specimen shape. To understand the corresponding relationship between the tensile properties and the shear properties of an anisotropic tube, the uniaxial tension stress-strain relationship was equivalently transformed to the shear stress-stain relationship using the Mises, Tresca, Hill48, and Barlat-lian constitutive functions. Results: After optimizing the specimen shape, the shearing condition of the tested tube is closer to the pure shear stress state. Based on the tests, the pure shear stress state can be maintained to a large deformation extent. The experimental shear stress-strain relationship was compared with the converted stress-strain relationship based on the uniaxial tension tests using the Mises, Tresca, Hill48, and Barlat-lian constitutive functions. The results show a large difference between the transformed stress-strain relationship and the shear stress-strain relationship. Conclusions: This testing method can provide necessary empirical data with the principal stress directions along the direction at an angle of 45° to the tube axis. The shear plastic deformation properties of some anisotropic materials cannot be equivalently described by the experimental data of the tensile test. The shearing characteristics obtained by this novel experimental method can be applied to the characterizations of anisotropic constitutive relations for simulations of tube deformation processes. [ABSTRACT FROM AUTHOR]

Pure shear tests of textured magnesium AZ31B sheet samples were carried out using a 5 kN Kammrath & Weiss in situ tension-compression stage in a scanning electron microscope in combination with real-time electron backscatter diffraction lattice orientation mapping. The sample design was optimized to produce a pure shear stress in the central gauge zone. Distributions of the deformation twins were correlated with finite element simulations using a linear-elastic constitutive law considering large deformations to show that twins form in areas where the principal compressive stress σ 3 * is a maximum and that they form normal to the trajectories of that minor principal stress. Mappings of the same area at different load values revealed the formation and growth of individual twins and their relationship to the internal elastic strain of individual grains as indicated by the internal grain disorientation. All twins observed were of the extension type, with an 86.3° disorientation with respect to the parent grains. A more detailed study was conducted using transmission electron microscopy to correlate with the EBSD observations and to further elucidate the twin structures within samples. [ABSTRACT FROM AUTHOR]

Nowadays precast concrete multi‐story dual system structures require Finite Element Method structural analysis. The stiffness of the vertical connections between wall panels influences the internal forces distribution. European standard EN 1992‐1‐1 recommends verification of strength and deformability of precast connections to be assisted by testing. Six different connection layouts were tested under pure shear with a special attention towards deformability. All connections showed close to/equivalent monolithic initial stiffness. Depending on the connection layout, the post‐cracking stiffness is reduced. The equation for shear resistance of interfaces between concrete cast at different times according to EN 1992‐1‐1 can lead to significant estimation errors due to its weak physical meaning (in disagreement with experimental observed failure mechanisms). A non‐linear finite element analysis solution strategy is validated by experimental results that shows how stochastic parameters can inflict large variation in terms of strength and stiffness. [ABSTRACT FROM AUTHOR]

The equations governing the simple shear deformation of an incompressible inelastic material undergoing finite strain are derived in this paper. The constitutive assumptions are kept in their most general form to allow the incorporation of widely used viscoplastic or viscoelastic models from the literature. It is shown that, while for a hyperelastic material the simple shear problem is completely determined by a single parameter, the amount of shear, in the viscoplastic case, the elastic deformation is the superposition of a triaxial stretch and a simple shear, whose determination requires the solution of three coupled nonlinear evolution equations. We evaluate such a solution for different material models and compare it with three-dimensional finite element simulations to assess its accuracy. We further assess the performance of these models using experimental data from filled rubber, focusing on their ability to capture the observed behaviour, such as the well-known Payne effect. Additionally, we extend our simple shear solution to address torsion and the extension of thin-walled cylinders. These derivations and analyses offer valuable insights for experimentalists engaged in the mechanical characterization of soft materials. [ABSTRACT FROM AUTHOR]

Torsion shaft was found broken as strip operation of the air starter was completed, while air starter over-speeding message came on multiple functional display (MFD) during startup of an aero-engine. Two failed shaft parts were received by the investigating team for failure analysis. The failure of both the components has occurred under the influence of maximum shear stress acting perpendicular to the shaft major axis. The fracture surfaces show the presence of shear dimples, the extent of which increases from center to periphery of the shaft. Rubbing is observed across the major part, most likely due to the running of the shaft for few cycles even after the failure of the shaft. Microstructure, hardness values and chemical compositions of both failed shaft parts indicate that the material of construction is close to 30KhGSHA. Two distinct appearances with whitish and bluish color along with slight difference in dimensions as well as in microstructures (discontinuous and continuous banding) indicate the probability that the received failed parts belong to two different shafts. However, the parts are said to be from one single failed shaft only, as by the user. Thus, the above-mentioned differences have been ascribed to the local variations in thermo-mechanical processing employed and subsequent heat treatment. An additional factor may have been frictional heating which has altered the microstructures in localized regions. [ABSTRACT FROM AUTHOR]

Pure shear tests of textured magnesium AZ31B sheet samples were carried out using a 5 kN Kammrath & Weiss in situ tension-compression stage in a scanning electron microscope in combination with real-time electron backscatter diffraction lattice orientation mapping. The sample design was optimized to produce a pure shear stress in the central gauge zone. Distributions of the deformation twins were correlated with finite element simulations using a linear-elastic constitutive law considering large deformations to show that twins form in areas where the principal compressive stress σ3* is a maximum and that they form normal to the trajectories of that minor principal stress. Mappings of the same area at different load values revealed the formation and growth of individual twins and their relationship to the internal elastic strain of individual grains as indicated by the internal grain disorientation. All twins observed were of the extension type, with an 86.3° disorientation with respect to the parent grains. A more detailed study was conducted using transmission electron microscopy to correlate with the EBSD observations and to further elucidate the twin structures within samples.

The paper presents the equations of the linear moment theory of elasticity for the case of arbitrary anisotropy of material tensors of the fourth rank. Symmetric and skew-symmetric components are distinguished in the defining relations. Some simplified versions of linear defining relations are considered. The possibility of Cauchy elasticity is allowed when material tensors of the fourth rank do not have the main symmetry. For material tensors that determine force and couple stresses, we introduce eigenmoduli and eigenstates that are invariant characteristics of an elastic moment medium. For the case of plane deformation and constrained rotation, an example of a complete solution of the two-dimensional problem is given when there are only shear stresses. The solutions turn out to be significantly different for anisotropic and isotropic elastic media. [ABSTRACT FROM AUTHOR]

Tissue mimicking materials are designed to represent real tissue in applications such as medical device testing and surgical training. Thanks to progress in 3D-printing technology, tissue mimics can now be easily cast into arbitrary geometries and manufactured with adjustable material properties to mimic a wide variety of tissue types. However, it is unclear how well 3D-printable mimics represent real tissues and their mechanics. The objective of this work is to fill this knowledge gap using the Stratasys Digital Anatomy 3D-Printer as an example. To this end, we created mimics of biological tissues we previously tested in our laboratory: blood clots, myocardium, and tricuspid valve leaflets. We printed each tissue mimic to have the identical geometry to its biological counterpart and tested the samples using identical protocols. In our evaluation, we focused on the stiffness of the tissues and their fracture toughness in the case of blood clots. We found that the mechanical behavior of the tissue mimics often differed substantially from the biological tissues they aim to represent. Qualitatively, tissue mimics failed to replicate the traditional strain-stiffening behavior of soft tissues. Quantitatively, tissue mimics were stiffer than their biological counterparts, especially at small strains, in some cases by orders of magnitude. In those materials in which we tested toughness, we found that tissue mimicking materials were also much tougher than their biological counterparts. Thus, our work highlights limitations of at least one 3D-printing technology in its ability to mimic the mechanical properties of biological tissues. Therefore, care should be taken when using this technology, especially where tissue mimicking materials are expected to represent soft tissue properties quantitatively. Whether other technologies fare better remains to be seen., (© 2024 Wiley Periodicals LLC.)

How the crust in the core of the Eastern Himalayan Syntaxis (EHS) deforms responding to the India‐Asia collision remains ambiguous. Here we present the first high‐resolution receiver functions image of crustal structure along a new NW‐SE trending dense nodal array crossing the core of the EHS. Two sets of low velocity zones (LVZs) are clearly observed: one with a flat style beneath the western Lhasa terrane and Higher Himalaya at 18–20 km depth and the other with two west‐dipping shapes below the western Yarlung‐Zangbo suture within 10–30 km depth. These LVZs caused by partial melting and aqueous fluids are disconnected, impeding the formation of crustal flow. A discontinuous east‐dipping intra‐crustal discontinuity and a sharp Moho offset of 7 km under the Aniqiao‐Motuo shear zone are identified, suggesting that the underthrusting of the Indian lower crust and pure shear mechanisms jointly dominate crustal deformation in the core of the EHS. Plain Language Summary: The tectonic evolution of the Eastern Himalayan Syntaxis (EHS) involves complex tectonic activities such as collision, subduction, and rapid exhumation, making the EHS an ideal site for studying the dynamics of continental collision processes. Strong crustal shortening occurs during the formation of the EHS, but the specific mechanism that accommodates this crustal deformation remains unclear. In this study, we construct a novel seismic image of crustal structure with unprecedented details along a recently deployed dense nodal array that traverses the core of the EHS. We observe two unconnected groups of low velocity zones, which call into question the validity of the crustal flow model in the core of the EHS. Our observations indicate that the underthrusting of the Indian lower crust and pure shear mechanisms, rather than a model of vertically coherent deformation, account for the present crustal deformation in the core of the EHS. Key Points: First high‐resolution image of crustal structure in the core of the Eastern Himalayan Syntaxis is constructed from P receiver functionsTwo disconnected groups of low velocity zones are observed in upper to middle crust, which prevents the development of crust flowAn intra‐crustal interface and a Moho offset we find suggest that underthrusting and pure shear mechanisms dominate crustal deformation [ABSTRACT FROM AUTHOR]

We study the shear behavior of pristine and uniaxially thermoformed auxetic foams using three different shear testing techniques and finite element simulations. A novel simple shear test rig with sliding lateral supports was developed and compared to fixed simple shear and diagonal pure shear rigs. The three rigs yield similar results at shear strains under 8 %, but the fixed simple shear rig shows a significant rise in shear modulus and stiffness at higher strains. In contrast, the sliding simple shear and diagonal pure shear rigs exhibit similar linear results up to 20 % shear strain. The thermoformed auxetic foam displays strong orthotropy, with a shear modulus of 35 kPa along the thermoforming direction and 0.1 MPa in the transverse directions. The pristine foam shows good isotropy under shear, with a similar 50 kPa shear modulus in all directions. The auxetic foam expands slightly along the thermoforming direction at high strains, while the pristine foam and auxetic foam in other directions show noticeable shrinkage. Finite element models based on 3D μ-CT scans, using a new boundary coupling element to apply periodic boundary conditions, closely matched the experimental results. The simulations revealed the deformation mechanisms within the foam cell structures that contributed to the observed orthotropic shear behavior. [ABSTRACT FROM AUTHOR]

Ideal morphologic representation of geologic structures using standard curves/surfaces can have far-reaching implications in estimating resources. From NW Lesser Himalaya (Uttarakhand state, India), field photographs of fully developed sigmoid-shaped brittle shear P- and ductile shear S- planes that crop out on the NW–SE (sub)vertical natural sections of rocks are matched by drawing curves using the B-spline tool in Rhinoceros software 5 SR service in 2D. These curves are advantageous to handle since the user can control their degrees, the control points are not the deciding factors, and that local modifications in shapes are permitted, unlike the Bézier curves. Sigmoid shapes are analyzed in detail using six shape parameters (lengths in between control points: L1, L2 and L3; angles in between control points: α1, α2 and α3). Good correlations between L3 vs. L1, L2 vs. L3 and L1 vs. L2 reveal the relation between wavelength (λ) and amplitude of the sigmoids that are classified into four types. Strong correlation between α2 vs. α3 and (α3−α1) vs. (α1− α2) suggest only the Type I, II and III sigmoids possess 180° rotational symmetry. Regression models (R2 values) demonstrate that the sigmoid geometries are governed by (1) pre-existing or co-evolving regional structures and (2) lithologic composition. [ABSTRACT FROM AUTHOR]

One of the great challenges in the pure shear and simple shear tests is to maintain the deformation state and deformation homogeneity of a specimen under large deformations. For this reason, the aim of this work is to investigate the state of shear deformation and degree of deformation homogeneity of three different shear specimens. A simple and easily replicable methodology was proposed to estimate the degree of deformation homogeneity of specimens, while a time-independent kinematic vorticity parameter was employed to identify pure shear and simple shear deformation states. All data were obtained from full-field displacements that were extracted with the two-dimensional digital image correlation (2D-DIC) method. Specimens of polytetrafluoroethylene (PTFE) were tested using the modified slotted shear test and the V-notched rail shear test, which are used to induce a simple shear state. The planar tensile test was used to produce a pure shear state in a thin sheet of rubber-like material. For small deformations, both slotted and V-notched shear tests induced a good degree of deformation homogeneity along the shear path between the notches of specimens, mainly in the central region. However, the V-notched specimens buckled at large deformation, producing a decrease in the degree of deformation homogeneity. In this case, the results were qualitatively assessed due to the errors associated with out-of-plane motions. High degree of deformation homogeneity was also observed in pure shear specimens. All tests demonstrated to be effective for inducing a state of pure shear or simple shear. Results show that the two approaches can be used as supplementary tools for determining the state of shear deformation and degree of deformation homogeneity.

Background: A shear constraint was very recently proposed by Abedini et al. (Int. J. Solids and Structures 151: 118–134 2018) to evaluate and calibrate advanced non-quadratic anisotropic yield criteria and to eliminate what they called non-physical numerical artifacts in those criteria. Objective: This investigation points out that such a shear constraint is in fact unnecessary for plane-stress orthotropic plasticity in general. Methods: Using the well-known Hill's 1948 quadratic and Gotoh's 1977 quartic yield functions for orthotropic sheet metals in plane stress, it is shown analytically that pure shear stressing and pure shear straining loading conditions are not equivalent except for very special cases. By conducting a series of shearing experiments on an aluminum sheet metal, the actual test results are shown not to provide any unequivocal supporting evidence at all to the newly proposed shear constraint. Results: The so-called non-physical numerical artifacts of the non-equivalence in pure shear stressing and pure shear straining of a sheet metal are in fact the intrinsic features of an anisotropic material in general. Conclusions: The newly proposed shear constraint should thus not be accepted to be universally applicable at all for anisotropic plasticity modeling of sheet metals. Such a proposed constraint itself shall be regarded as a provisional simplifying assumption of reduced anisotropy only for some particular sheet metals under consideration. [ABSTRACT FROM AUTHOR]

The extreme stretching of dielectric elastomers in sensors, actuators and energy harvesting devices is a common phenomenon where the materials are prone to fracture under the influence of flaws and notches. In this work, we have investigated the length of flaw sensitivities of two widely used dielectric materials, acrylic (VHB) and silicone (Ecoflex) elastomers under a pure shear loading and established that the length of flaw sensitivity of acrylic is almost double than that of silicone. Therefore, the acrylic elastomer is safer to operate for small notches as compared to the silicone material. However, within the flaw-sensitive length, failure stretch, fracture toughness and failure stress are more for Ecoflex than those for VHB. It is found that the failure stretch and the fracture toughness decrease drastically after the length of flaw sensitivities for both materials. Also, the failure stress keeps on decreasing with an increase in notch length for both materials. Afterwards, a simple phenomenological relation is proposed for fitting experimental results under a pure shear loading with only two parameters. The mathematical relation is valid for both the materials and covers the notch sensitivity with a good agreement. [ABSTRACT FROM AUTHOR]

This paper presents the analytical solution of the crack tip fields as well as the crack parameters in an infinitely large composite plate with a central crack subjected to pure shear loading. To this end, the complex variable method is employed to formulate an asymptotic solution for the crack tip fields in an anisotropic plane. Using a stress‐based definition of the crack tip modes of loading, only the mode II crack parameters are found to be non‐zero under pure shear load. Special focus is given to the determination of the higher order parameters of the crack tip asymptotic field, particularly the first non‐singular term, ie, the T‐stress. Unlike the isotropic materials, in which the T‐stress is zero under pure shear, it is found that the T‐stress is non‐zero for the case of anisotropic materials, being the only material‐dependent crack tip stress parameter. The veracity of our exact crack tip fields is assessed and verified through a comparison made with respect to the finite element (FE) solution. Finally, we demonstrate the significance of the T‐stress on stresses near the crack tip in composite plates under pure shear loads. [ABSTRACT FROM AUTHOR]

Shear is a basic deformation mode governing yielding, plasticity and fracture in metallic solids. For amorphous metals, due to various constraints, little work is available in addressing directly shear deformation and shear-induced mechanical property changes which are vital to the mechanistic understanding of this new class of disordered materials. Here, by using a finite deformation theory, we examine the pure shear deformation in a bulk metallic glass in a large range of shear strains. With the continuum approach, we show systematically for the first time the detailed shear deformation behaviours, shear-induced normal stress and strain relations, softening in the elastic constants, volume dilatation and free energy change induced by the shear deformation. These results point to two major consequences from the shear deformation, one is the mechanical degradations and the other material degradation which is responsible for the changes in the mechanical properties of the disordered materials. [ABSTRACT FROM AUTHOR]

In-plane shear is considered as the main deformation mechanism during the forming of fabrics on double curved geometries. Non-Crimp Fabrics (NCFs) are more and more used in the industry thanks to their high mechanical performances. The uniaxial bias extension (UBE) test is commonly used for characterizing the in-plane shear behavior of fabrics. However, presence of slippages calls the reliability of this test into question for NCF material. These slippages lead to a macroscopic kinematic which does not respect the fundamental hypotheses of UBE test theory. The variety of NCF architectures is usually pointed while the lack of standardized experimental methods is seldom discussed. The first section of this paper presents a two-way approach to detect slippage on an NCF. This approach is based on two kinematical descriptions of the UBE test. The first one assumes a pure shear behavior whereas the second one assumes a simple shear behavior. These behaviors correspond respectively to the rotation of fibers and to the slippage of fibers from a macroscopic point of view. In the second section, the two-way approach is used to analyze experimental UBE tests. This investigation highlights the influence of the sample width on the deformation mode during a UBE test. More precisely, it is shown that increasing the sample width of NCF specimens improves the UBE test reliability. [ABSTRACT FROM AUTHOR]

Folds in rocks are commonly used in geology for strain analysis. They contain information about rock rheology, and the kinematics and mechanics of deformation. The systematic analysis of the evolution of stress and strain during rock folding can provide key information on the mechanical behaviour of rocks and the efficiency of the folding process. In order to investigate the evolution of rock rheology during fold development, a series of two-dimensional simulations of single-layer folding are presented here. They are run using the finite element method BASIL, integrated within the software platform ELLE, to simulate linear and non-linear viscous deformation. The kinematics of deformation, the competence ratio between the folding layer and surrounding matrix as well as the stress exponent of the power-law viscous material are systematically varied. The results allow comparing the stages of folding under different deformation kinematic conditions. For all simulations the folding amplification process starts when the second invariant of the strain rate tensor in the competent layer deviates from the theoretical strain rate curve for a homogeneous material, which corresponds to a viscosity ratio between layer and matrix of m = 1. The relative time when the fold amplification starts is determined by the viscosity ratio between the competent layer and its surrounding matrix, the initial layer orientation with respect to the shear plane, the kinematics of deformation and the stress exponent. The folding process is more effective in cases with high viscosity ratio, non-linear rheology and layers initially oriented at a low angle with respect to the shear plane, because the second invariant of the strain rate tensor at the layer deviates earlier from the theoretical curve. The results also show differences depending on the boundary conditions, where (1) folding a competent layer requires less work in simple shear than in pure shear, and (2) the geometrical softening experienced by the competent layer due to fold development is followed by a hardening stage in pure shear and by a major softening phase in simple shear. The simulation results suggest that the decrease of stress of a competent layer without decreasing the mechanical strength has a direct influence on the behaviour of a lithospheric layer around the crust-mantle boundary, which may experience geometrical softening depending on the tectonic settings rather than material softening due metamorphic reactions or grain size reduction. • Simulations of a single layer deformed in pure and simple shear are presented. • The stress and strain evolution of the layer during deformation is investigated. • Viscosity ratio, layer orientation and stress exponent have a first-order impact on folding. • Geometrical softening is clearly observed in pure and simple shear simulations. [ABSTRACT FROM AUTHOR]

Abstract Fracture patterns in folds are resulting from complex tectonic history. Indeed, in thrust and fold belts fractures occurred because of three different stress tensors: (1) Regional field stress, (2) Tensile stress in hinge area or (3) simple shear in limbs. Therefore, the same regional stress field could create too many different fracture and joint types. Detailed works have characterized fractures observed in nature, but only few studies have linked the fractures to the fold kinematics. On the other hand, we believe that fold kinematics have a key role in fracture amplitude and distribution. For this reason, we studied the fracture network affecting the Jebel Sehib, a typical fault-propagation fold of the Gafsa basin, southern Tunisia. On the same bed, and all over fold parts, we measured the fracture net density. The results showed clear difference in fracture density spread with highest density in the forelimb, medium in the backlimb and lowest in the hinge area. The, we compared the results with the theoretical kinematics of related fold/fracture models. We concluded that the fracture net is mainly anterior to the folding process. In fact, at the beginning of compressive stress, layer parallel shortening (LPS) occurred and generated homogenous fracture net in a pure shear regime attested by conjugated shear joints. During the growth of the fault-propagation fold, the existing fracture net is locally reactivated and amplified by limb simple shear as prospected in the mechanical behaviour of the fault-propagation fold. This leads to higher fracture density in the steeper flank. This hypothesis can be generalised to at least all fault-related folds in which limb simple shear is present. In the Jebel Sehib case study, we observed the flexural flow (internal deformation of the rock) because of the chosen massive limestone reference bed. In other natural examples, most of the beds accommodate simple shear by a flexural slip and rarely by flexural flow. This work have direct consequences on fractured reservoirs exploration in fault-related folds. Highlights • Relationship between fractures density and folding in fault propagation fold. • Fault-related fold kinematics and mechanical behaviour. • Limb simple shear mechanics while folding. • Fracture density study on a massive limestone bed. • Role of inherited faults in foreland basin folding. [ABSTRACT FROM AUTHOR]

The Bauschinger effect during the plastic deformation of metals, i.e., steels of a number of grades, is presented. The hypothesis of an even dependence of the asymptotic value βm in a function β(e), which characterizes the Bauschinger effect, on Lode parameter μ is considered. A relation is proposed to determine β as a function of cumulative strain e, Lode parameter μ, and parameter βm determined by reverse loading under conditions of pure shear () and linear stress state (). Talypov's hypothesis about an even dependence of βm on μ in tension–compression and compression–tension loading cycles is experimentally substantiated. The experimental data confirm the calculated values of β(e) at a sufficient accuracy. [ABSTRACT FROM AUTHOR]

In order to estimate mode I fracture strain energy release rate of a rubber upon monotonic loadings, the material is submitted to pure shear and single edge notch tension tests. Catastrophic failure happens suddenly for both tests, revealing mirror-like crack surfaces, assessing the fragile fracture. Nonetheless, Griffith failure analysis could be carried out on pure shear tests only. This analysis leads to an energy release rate value that allows challenging approximate expressions existing in the literature for pure shear and single edge notch tension tests. The pure shear approximate expression provides quantities that match the Griffith analysis. Meanwhile, the strain energy release rate values calculated directly from the single edge notch tension tests differ significantly from the values obtained in pure shear. This discrepancy is explored and possible explanations are discussed showing that pure shear tests should be favored. [ABSTRACT FROM AUTHOR]

Quantifying the higher-mode effects on the seismic demands of buildings may benefit not only the awareness of characteristics of the seismic responses of buildings, but also the development of rapid/simplified methods for the seismic assessment of buildings. This study proposes an approach that is applicable for quantifying the aforementioned effects, covering the full range of building heights and deformation types. The vehicle used in this proposed approach is the generalized building model, which has been modified from the conventional cantilever beam model. In addition to building height and deformation type, the strength ratio of each vibration mode and the site class of buildings are the parameters considered in this study. The higher-mode effects on floor displacements, inter-story drift ratios, floor accelerations, and base shears with relation to the aforementioned parameters are investigated. Finally, the proposed approach is verified via the investigation of the higher-mode effects of a 20-story exemplar building. [ABSTRACT FROM AUTHOR]

This paper considers the characteristics of severe plastic deformation (SPD) to estimate its efficacy and to compare different processing techniques. In contrast to effective strains by von Mises and Hencky, the rotation component of the strain rate is included in the analysis as a mode of deformation, which ranges from simple shear to pure shear. Distortions of material elements during a uniform plane plastic flow are calculated using a kinematic approach. For the fixed deformation mode, the current state is defined by the accumulated shears that are identical to the von Mises effective shear strains. In specific cases of pure shear and simple shear, the accumulated shears match the specific distortions of round or square elements prescribed by Hencky or von Mises approach, respectively. The mode of deformation is important to the structural effects of SPD. In general, two separated characteristics, accumulated shear and the coefficient of deformation mode, are necessary to describe strains during SPD. [ABSTRACT FROM AUTHOR]

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Macroscopic failure of polystyrene has been investigated under pure shear and simple tension by isochronal static tests in air at room temperature. A number of crazes were clearly observed under both stress states. The craze initiation identified under pure shear provides an obvious counterevidence to the current criteria, which involve explicitly the dilatational stress term as a requisite for craze initiation. A criterion expressed by a product form of the maximum principal stress and the maximum principal shear stress with an isotropic stress term was examined. The proposed criterion was marked to predict α priori a peculiar feature that the craze initiation never takes place under biaxial compression. A theoretical ratio of critical stress for craze initiation under pure shear to that under simple tension coincided with the experimental result.