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In this paper, the first‐principles method is used to calculate the electronic structure of the intrinsic WSe2 system and the Ca adsorbed WSe2 system under shear deformation, and the diffusion barrier of Ca on WSe2 is studied in depth. The results show that shear deformation can effectively reduce the band gap of WSe2 system, and shear deformation can easily lead to the transition from semiconductor properties to metal properties. The adsorption of Ca leads to the change of the band structure of WSe2. The contribution of Ca‐d electrons leads to an increase in the peak in the range of 3–6 eV. The shear deformation reduces the diffusion barrier of Ca on the WSe2 surface. This paper provides an improvement method for the application of WSe2 in the field of battery. [ABSTRACT FROM AUTHOR]

Highlights Textile composites are advanced materials composed of preforms combined with matrix materials. The fiber structure in the preform has a significant impact on the mechanical properties of the composite. Precise control over preform dimensions and internal fiber structural uniformity, termed ‘accurate shape control’, is essential to ensure reliable and stable composite component mechanical properties. This paper reviews current research progress on fabric deformation mechanisms, focusing on experimental characterization and numerical simulation. Experimental methods for fabric deformation include tensile, compression, bending, and shear deformation, whereas numerical methods encompass macroscopic continuum, discrete, and semi‐discrete models. The insights offered in this paper will aid a greater understanding of fabric deformation mechanisms, enabling an accurate prediction of complex shape molding and effective process parameter design, ultimately facilitating the structural design and engineering applications of textile composites. Recent trends and challenges in the study of fabric deformation mechanisms are presented. The experimental methods for fabric deformation were summarized and evaluated. Representative numerical modeling techniques and simulation methods are discussed. Some recommendations on potential future research directions are detailed. [ABSTRACT FROM AUTHOR]

The mechanical response of granular materials, exemplified by frictional grain interactions, is characterized by a critical state in which deformation occurs without change of material volume or stresses when subjected to large shear deformation. In this work, a granular micromechanics approach (GMA) based continuum model is used to investigate the emergence of such a critical state. The continuum description is constructed through mechanical concepts based upon elastic and dissipation energies defined for a generic grain‐pair interaction. A hemivariational principle provides the basis for considering the evolution of damage and plasticity phenomena comprising grain‐pair contact loss and irreversible deformation. As a consequence, the Karush–Kuhn–Tucker (KKT)‐type conditions are derived, which give the evolution equations for the irreversible phenomena. Notably, in this derivation there is no invocation of flow rules and other similar assumptions of classical phenomenological continuum damage and plasticity. Further, Piola's ansatz is elaborated to kinematically connect granular micromechanics of grain‐pair to the continuum description. While the concept of critical state analysis has been handled with either phenomenological approaches or discrete numerical frameworks, in the present paper this concept is examined within a micromechanics‐based continuum description. The constitutive model is established and the coupled damage and plastic irreversible quantities are assessed. The critical state is shown to emerge as grain‐pair related damage and plastic evolution in a competitive/collaborative manner during the imposed loading path. [ABSTRACT FROM AUTHOR]

In this paper, a numerical critical shear crack model, in which the shear‐flexural coupling effect is considered and the full process of stress and strain is captured, is proposed to evaluate the post‐peak behavior of reinforced concrete (RC) and steel fiber reinforced concrete (SFRC) beams. The shape of critical shear crack is identified by combining the modified compression field theory considering the bridge effect of steel fibers and the section analysis method. Based on the shape of critical shear crack, the shear capacity of beam members is provided by the shear tension zone and the shear compression zone. The shear capacity of the shear tension zone is calculated by the modified compression field theory and that of the shear compression zone is determined by multiaxial strength criterion of concrete. The vertical displacements caused by the flexure deformation and shear deformation are deduced by the moment area method and integration of shear strain. To verify the proposed numerical approach, a test database of 486 RC beams and 313 SFRC beams was established to predict the shear strength, and the force‐displacement relationships of twelve beam members are used to validate the feasibility for full process analysis. The stochastic analysis of beams with different failure modes is conducted via GF‐discrepancy‐based point selection method and probability density evolution method. The limitation between different failure modes is defined according to the degradation percent of shear capacity and it is taken as threshold value of failure domain, and the failure probability analysis indicates that the designed flexure beam member suffered severe degradation of shear capacity, resulting in a significant decline in safety probability. [ABSTRACT FROM AUTHOR]

This paper uses the analytical method with arbitrary boundary conditions to model and analyze the free vibrations of multi‐directionally functionally graded porous (MFGP) doubly‐curved shallow shells resting on the Pasternak foundation in a temperature environment. It is anticipated that all mechanical parameters, except Poisson's ratio, will change in the direction of length, width, and thickness. To comprehensively describe the shell's displacement, strain, and stress fields, a modified first‐order shear deformation theory (FSDT) with an assumption of cosine distribution shear stresses has been developed. The fact that the enhanced FSDT theory does not require the use of shear correction and that the shear stress at the two free faces of the shells is zero are two of the theory's most significant advantages. Using Hamilton's principle and improved FSDT, one may get the governing equation for free vibration analysis of MFGP doubly‐curved shallow shells. The Galerkin approach is proposed to solve the governing equation of MFGP doubly‐curved shallow shells with various boundary conditions. The trustworthiness of the article is evaluated via its publication in the article model's several special cases. From this point on, a collection of findings about the natural frequency of MFGP doubly‐curved shallow shells is identified and shown in the form of tables and graphs. The results provided in this manuscript can be used as a benchmark solution for further studies as far as the vibration behavior of the MFGP doubly‐curved shallow shells is concerned. [ABSTRACT FROM AUTHOR]

In this paper, the dynamic performance of Multi‐layered Sandwich Composite Cylindrical Open Shells (MSCCOS) with double‐layered soft cores is analyzed for the first time by adopting the First‐order Shear Deformation Theory (FSDT). For accomplishing this aim, vibration differential equations of MSCCOS are derived based on Hamilton's variance principle. Then, the closed‐form Navier solution is introduced to obtain the numerical results of differential equations. Subsequently, the effectiveness and accuracy are discussed by several comparisons. Ultimately, the dramatic effect of different structural and material parameters on natural frequencies and associated loss factors is investigated and described vividly. Because shear deformation and rotary inertia of all layers are considered in vibration differential equations, thin and moderately thick MSCCOS could be researched, and some interesting discoveries for the dynamic performance of MSCCOS are derived. Highlights: A vibration model of five‐layered composite open shell was obtained.The optimal structure parameters maximizing the damping properties are shown.Dynamics properties of five‐layered composite open shell are presented. [ABSTRACT FROM AUTHOR]

Analogous electrical networks were previously derived from the Euler–Bernoulli and Kirchhoff–Love theories to represent beams and plates, respectively, for use in multimodal structural vibration damping. However, these networks do not account for shear deformations or rotary inertia, which can result in suboptimal vibration damping performance when used on moderately thick beams and plates. In this paper, we investigate the incorporation of shear deformation and rotary inertia using Timoshenko–Ehrenfest beam theory and Mindlin–Reissner plate theory to develop improved electrical networks that can more accurately represent thick beams and plates. Our findings suggest that the inclusion of shear deformation and rotary inertia can significantly improve the frequency coherence of the electrical networks and multimodal vibration damping for thicker structures. The electrical analogs presented here are of use for various applications, especially to conveniently design complex circuit topologies in fields spanning from vibration attenuation to energy harvesting. [ABSTRACT FROM AUTHOR]

Graphene is a highly conductive and exceptional material that has shown potential for significantly improving the piezoelectric and mechanical properties of piezoelectric matrix. This paper examines the stability of composite plates surface bonded with graphene‐reinforced composite piezoelectric (GRCP) actuators. However, the significant differences in material characteristics at the interfaces will pose some challenges in analyzing the buckling behavior of piezoelectric composite plates by means of existing higher‐order shear deformation theories. To address this issue, a refined plate theory is developed for the buckling analysis of piezoelectric composite plates. The developed theory includes a new interlaminar shear stress field that precisely describes the distribution of interlaminar shear stresses, which differs from earlier higher‐order theories. It should be emphasized that the finite element formulation can be simplified by removing the second‐order derivatives of in‐plane displacement parameters from interlaminar shear stresses. In terms of the developed theory, a four‐node C0 quadrilateral plate element is introduced to examine the buckling behavior of piezoelectric composite plates. Furthermore, the modified interlaminar shear stress field is absorbed into the strain energy, significantly improving the ability to predict the critical loads of composite plates with GRCP actuators. The refined plate model is evaluated through the utilization of three‐dimensional (3D) elasticity solutions and results obtained from other associated theories. Numerical results demonstrate that the refined plate model is capable of producing favorable results, and a comprehensive examination is conducted to analyze the effects of significant parameters on the buckling behaviors of piezoelectric composite plates. This study sets a solid foundation for future research and development on the application of graphene‐reinforced composite piezoelectric actuators in composite structures. Highlights: Buckling analysis of composite plates with GRCP actuators is conducted.A refined plate theory with modified interlaminar shear stresses is developed.The ability to predict critical loads can be significantly improved.The finite element formulation can be simplified based on the proposed model.Comprehensive parametric studies on buckling behavior are caried out. [ABSTRACT FROM AUTHOR]

Reinforced concrete deep beams in bridges and other critical infrastructure are subjected to millions of load cycles during their service life. At the same time, they typically work with high shear and develop critical diagonal cracks. The cyclic loading across the cracks results in fatigue damage of the shear‐resisting mechanisms, which needs to be taken into account in the assessment of existing structures, and in particular in members with small amount of shear reinforcement built according to early design codes. To aid the development of advanced assessment approaches for such structures, this paper presents five large‐scale fatigue tests of deep beams with a stirrup ratio of 0.134%. The beams are preloaded to develop complete diagonal cracks, and then are subjected to cycles with different minimum and maximum load. The focus is placed on detailed crack measurements, needed for the development of crack‐based assessment approaches. The crack data is analyzed with the help of the two‐parameter kinematic theory to quantify important deformations. It is shown that the fatigue across the shear cracks is associated mainly with degradation of aggregate interlock and progressive damage in the critical loading zones. It is also shown that as the maximum load is decreased, the fatigue life increases, and the failure mode can switch from shear to flexure. [ABSTRACT FROM AUTHOR]

This paper presents and analyzes the nonlinear buckling responses of three types of shallow imperfect panels (cylindrical panel, parabolic panel, and half‐sinusoid panel) made from functionally graded graphene reinforced composite (FG‐GRC) on nonlinear elastic foundations subjected to axial compressive load in thermal environments. The nonlinear governing equations are formulated on Reddy's higher‐order shear deformation shell theory (HSDST) and take into account von Karman‐type nonlinearity. A new approximation technique to determine the stress function in average sense is developed and Galerkin's method is used to obtain the algebraically nonlinear equation system. Then, the simple calculation process can be used to solve the obtained equation systems, and the formulations to calculate the critical buckling loads and postbuckling load‐deflection curves are expressed in explicit form. The results can be flexibly applied to FG‐GRC panels with different curvatures in engineering designs. The effects of panel types, geometrical parameters, temperature increase, initial imperfection, and nonlinear elastic foundations on the critical buckling loads and postbuckling curves of cylindrical, parabolic, and half‐sinusoid FG‐GRC panels are discussed in numerical results. Numerical results also show a small disadvantage in the load‐carrying capacity of cylindrical panels compared to parabolic panels and half‐sinusoid shallow panels. Highlights: Postbuckling of cylindrical, parabolic, and half‐sinusoid panels are studied.The panels are made of functionally graded graphene reinforced composite.Reddy's higher‐order shear deformation shell theory is applied.A new approximation technique to determine the stress function is developed.Critical buckling loads and postbuckling expressions are explicitly obtained. [ABSTRACT FROM AUTHOR]

During a shear process the vibrational mode structure of a non‐crystalline model material will change under load. Thus, we expect an effect on the characteristic boson peak, which correlates with numerous features of disordered materials. In this paper, we perform shear deformation on two‐dimensional random network materials and investigate the distribution of their vibrational density of states (VDOS). Furthermore, the spectra of eigenvalues are studied in detail using similar approaches to investigate the eigenvectors and specifically their change due to load and plastic rearrangements. [ABSTRACT FROM AUTHOR]

In this paper, the double‐side direct shear experiments on the specimens with and without grooves were conducted to measure the shear load‐deformation curves of steel fiber‐reinforced concrete containing recycled coarse aggregate (SFRCA). The evaluation method for shear toughness was proposed first, and then the effects of water–cement ratio, replacement ratio of recycled coarse aggregate, volume content of steel fibers, and shear section height on the shear toughness of SFRCA were experimentally analyzed. The results showed that the proposed shear toughness evaluation method could reflect the shear toughness of SFRCA. The effects of the replacement ratio of recycled coarse aggregate and the volume content of steel fiber on the shear toughness of specimens with grooves had the same trend as those of specimens without grooves. The shear toughness ratio of SFRCA increased with the increase of the volume content of steel fibers, and decreased with the increase of water cement ratio and the replacement ratio of recycled coarse aggregate, respectively. Moreover, the residual shear toughness ratio increased almost linearly with increasing water–cement ratio, replacement ratio of recycled coarse aggregate, and volume content of steel fibers, and decreased with the increase of shear deformation, respectively. Finally, the formula for calculating the residual shear toughness ratio of SFRCAC was proposed by fitting the test results. [ABSTRACT FROM AUTHOR]

Small amounts of shear reinforcement are often assumed to increase the shear capacity of RC beams, compared to an identical beam without shear reinforcement. However, in a recent experimental campaign, the shear capacity of beams with a shear reinforcement ratio below the minimum requirements according to the design standards turned out to be similar to identical beams without shear reinforcement. This paper presents a detailed analysis of why the shear capacity may be similar for beams without‐ and beams with small amounts of shear reinforcement. This includes the influence of small amounts of shear reinforcement on the shear behaviour and shear‐transferring mechanisms. The analysis shows that the crack development is more severe at the ultimate load for beams with a small amount of shear reinforcement compared to beams without shear reinforcement. This more severe crack development is shown to cause an overestimation of the shear contribution from aggregate interlock when applying a well‐known constitutive model often used for beams without shear reinforcement. Therefore, a new expression for the aggregate interlock stresses is proposed. A comparison of the proposed expression with Mixed‐Mode crack opening tests shows a good agreement with the test for both small and large crack openings. By applying the proposed expression on the measured crack kinematics it is shown that for a large shear contribution from aggregate interlock the shear contribution from the shear reinforcement is very limited and as the aggregate interlock stresses decrease the shear contribution from the shear reinforcement increases. This shift in the governing shear‐transferring mechanism can help to improve the requirements for the minimum shear reinforcement often found in the design standards. [ABSTRACT FROM AUTHOR]

The strength and deformation of full‐scale adhesively bonded multi‐material joints is studied in this paper. Four joints with a thick layer of methyl methacrylate adhesive (MMA) have been manufactured in shipyard conditions. In two specimens, cracks have been introduced at steel–adhesive and composite–adhesive interfaces. One cracked and one un‐cracked specimen were subjected to quasi‐static tensile testing; the two remaining specimens were stepwise loaded/unloaded with increasing load until failure. The strain in the adhesive layers was measured with digital image correlation (DIC). This showed a predominant shear deformation and dissimilar shear strain patterns for different bond lines. Fibre Bragg (FBG) sensors were used to monitor strains at steel and composite constituents and to detect the onset and evolution of damage in the un‐cracked specimen. Strains measured by FBG sensors correspond well with DIC results at nearby regions. All specimens failed by delamination of the composite panel near the composite–adhesive interface. [ABSTRACT FROM AUTHOR]

During earth pressure balance (EPB) shield tunnelling, a three‐dimensional stress redistribution occurs, which leads to development of soil arching. In this paper, development of soil arching by stress redistribution in two types of soils, silty and sandy soil is studied. A three‐dimensional numerical model was first developed and validated using the case study of the extension of Dwaraka Najafgarh Metro Corridor of Phase‐III of Delhi MRTS. Using the validated model numerous simplified numerical analyses were carried out to determine the evolution of soil arching in both silty and sandy soil. The variation in stresses (σxx, σyy and σzz), deformation and shear strain were evaluated and, on this basis, the extent of the loosened region and soil arching region was determined for both soil types. Furthermore, impact of different parameters (i.e., face pressure, grout pressure, C/D ratio and diameter of tunnel) on the evolution of loosened region above tunnel crown was assessed. Based on the numerical analysis, the extent of loosened region in the vertical direction for silty soil was determined to be 1.21D from the tunnel crown and the extent for the sandy soil was determined to be only 0.73D. While in the horizontal direction, the loosened region extends up to 0.72D and 0.37D for silty and sandy soils respectively. An optimal range of different parameters which must be adopted at the time EPB shield tunnelling in silty and sandy soil is recommended. [ABSTRACT FROM AUTHOR]

In this paper, the shear behavior of glass fiber reinforced polymer (GFRP) bars reinforced ultra‐high‐performance concrete (UHPC) beams was investigated through experimental tests. Eight GFRP bars reinforced UHPC I‐beams were tested until shear failure with various stirrup ratio, reinforcement ratio, and shear span to depth ratio. The shear capacity, load–deflection relationship, cracking pattern, and failure mode were investigated in detail. The results show that the shear span to depth ratio has the greatest influence on the shear capacity of the beam among the three parameters, followed by the stirrup ratio and reinforcement ratio. The stirrup configuration can significantly improve the shear capacity and deformation resistance of the beam and can effectively reduce the stress concentration caused by the uneven distribution of steel fibers, which affects the failure mode of the beam. Increasing the stirrup ratio and reinforcement rate can improve the stiffness of the beam after cracking, and the larger the shear span to depth ratio is, the more significant the improvement effect is. Moreover, the stirrup enables the full development of the tensile capacity of GFRP bars. The existing equations of shear strength from five design codes and seven literatures are compared to the experimental results of 54 UHPC beams. It showed that the formula from the codes AFGC‐2013 and JSCE‐2006 codes is more accurate. The equations by Kwak, Jin, and Thiemicke's provide the best predictions. [ABSTRACT FROM AUTHOR]

This paper presented the formulation of a novel hypoplastic model for sand considering both the cyclic mobility and large accumulative shear deformation in the post‐liquefaction stage. Based on experimental observations and existing modeling response, two constitutive ingredients were incorporated into the hypoplastic model to improve its prediction accuracy. First, the fabric change effect was considered, enabling a satisfactory simulation of effective stress reduction under undrained cyclic loading. The second component was the introduction of the semifluidized state concept to reflect the modulus degradation and deviatoric strain development of sand at low‐stress state. The capability of the proposed model is demonstrated by the comparisons between the model responses and experimental results of the cyclic behavior of sand under different test conditions. Remarkably, the liquefaction phenomenon and increasing deviatoric strain amplitude during the post‐liquefaction stage were reproduced well by the model. [ABSTRACT FROM AUTHOR]

This paper proposed a new analytical approach for the nonlinear buckling behavior of axially compressed functionally graded graphene reinforcement composite laminated (FG‐GRCL) stiffened cylindrical panels with the piezoelectric layers resting on the Pasternak's elastic foundation in the uniformly distributed temperature change. A design for the reinforcement of stiffened cylindrical panels is applied where the polymer matrixes of panels and stiffeners are reinforced by graphene sheets. The effects of FG‐GRCL stiffeners are modeled using the improved smeared stiffener technique, which is developed by applying the anisotropic higher‐order shear deformation beam theories for curved and straight stiffeners. The fundamental formulations are obtained by applying Reddy's higher‐order shear deformation theory (HSDT), and taking into account the von Kármán geometrical nonlinearities. The algebraically nonlinear equilibrium equations are achieved by employing Galerkin's procedure, and then they can be solved by using the ordinary calculation process. Some important remarks on the nonlinear buckling of stiffened FG‐GRCL cylindrical panels are archived from the numerical investigation process. [ABSTRACT FROM AUTHOR]

In this paper, N, Nb composite doped lithium iron phosphate structure was constructed, and its thermodynamic stability, intercalation voltages, volume change rate, electronic structure properties, and mechanical properties were systematically investigated using the first principles. The results of formation energy demonstrate that the N and Nb composite doping system meets the thermodynamic stability requirements and can exist consistently. In the process of de‐lithium, the volume change rate of the anion‐cation hybrid doping system is significantly decreased, and the intercalation voltage is increased, which indicates that the doping makes the cycling performance and energy density of the material improved. A radical shift in the material's electronic structure after doping is conducive to the enhanced conductivity of lithium iron phosphate. Besides, studies on the elastic properties of materials demonstrated that both N and Nb doping inhibited the generation of microcracks and diminished the occurrence of shear deformation. [ABSTRACT FROM AUTHOR]

Multi‐directional forging technology, as a representative severe plastic deformation technology, is urgent to be developed because it has strong microstructure refinement and performance improvement effects. In this paper, multi‐directional forging experiments of TA15 titanium alloy with different passes were carried out at 700 °C using unrestricted multi‐directional forging die structure. Then the samples of TA15 titanium alloy after multi‐directional forging deformation were subjected to a high‐temperature vacuum annealing treatment. The test results reveal TA15 alloy was effectively refined through multi‐directional forging without any cracking with the increasing of deformation passes. The mechanism of grain refinement during multi‐directional forging included dynamic recrystallization, grain crushing and adiabatic shear deformation bands refinement. The amount and grain size of recrystallization grains increased when the annealing time increased from 1 hour to 4 hours. Supplemented by annealing, the adiabatic shear deformation bands microstructure with the mixed microstructure of coarse αp and fine αs were obtained and the hardness after multi‐directional forging and annealing was investigated. The yield strength and ultimate tensile strength increased by 26.1 % and 25.5 % respectively when the deformation pass increased to 3 passes compared with the initial specimen. The present work revealed that multi‐directional forging deformation combined with appropriate annealing could represent an efficient route to improve the microstructure and mechanical property of TA15 alloy. [ABSTRACT FROM AUTHOR]

Passive materials in human skeletal muscle tissues play an important role in force output of skeletal muscles. This paper introduces a multiscale modeling framework to investigate how age‐associated variations on microscale passive muscle components, including microstructural geometry (e.g., connective tissue thickness) and material properties (e.g., anisotropy), influence the force output and deformations of the continuum skeletal muscle. We first define a representative volume element (RVE) for the microstructure of muscle and determine the homogenized macroscale mechanical properties of the RVE from the separate mechanical properties of the individual components of the RVE, including muscle fibers and connective tissue with its associated collagen fibers. The homogenized properties of the RVE are then used to define the elements of the continuum muscle model to evaluate the force output and deformations of the whole muscle. Conversely, the regional deformations of the continuum model are fed back to the RVE model to determine the responses of the individual microscale components. Simulations of muscle isometric contractions at a range of muscle lengths are performed to investigate the effects of muscle architectural changes (e.g., pennation angles) due to aging on force output and muscle deformation. The correlations between the pennation angle, the shear deformation in the microscale connective tissue (an indicator for the lateral force transmission), the angle difference between the fiber direction and principal strain direction and the resulting shear deformation at the continuum scale, as well as the force output of the skeletal muscle are also discussed. [ABSTRACT FROM AUTHOR]

In this paper, the in‐plane shear deformation of unbalanced 3D interlock woven reinforcement (IWR) was investigated through experiments and finite element modeling. Five specimens with five layers warp (six layers weft) were designed and prepared. The warp is 792 tex carbon tows and weft is 396 tex carbon tows. This kind of reinforcement is unbalanced because that the linear density of warp is different from that of weft. The in‐plane shear deformation of unbalanced 3D IWR was tested by bias extension test. The bias extension process was simulated by finite element method from macro and meso scales. The results of simulation are basically consistent with experiments. The bias extension process can be divided into three stages: Meso scale deformation stage, multiscale deformation stage and Reinforcement failure stage. At meso scale deformation stage, the tensile load and shear angle are small when the displacement is less than 7.5 mm. There is no obvious change in the macro scale, while the weft slipping in the meso scale mainly occurs in area B. The deformation of B1 and B2 are asymmetric because the linear density of warp is different from that of weft. In the multiscale deformation stage, asymmetric deformation at the macro scale begins to appear when the displacement is between 7.5 mm and 20 mm. There is obvious in‐plane shear deformation in area C at the meso scale. In the reinforcement failure stage, A large number of weft yarns are pulled out from the reinforcement in area B. [ABSTRACT FROM AUTHOR]

The dynamic stability response of a micro sandwich beam with leptadenia pyrotechnica rheological elastomer (LPRE) core is studied. The top and bottom layers respectively are assumed as piezoelectric reinforced with carbon nanotubes (CNTs) and porous functionally graded materials (FGM). The core and top layers are affected by magnetic and electric fields for the magnetic and piezoelectric characteristics of the layers, respectively. The Halpin‐Tsai micromechanics theory for obtaining the effective material properties of the nanocomposite layer is utilized. On the basis of Kelvin‐Voigt model, the structural damping of the smart micro beam is assumed. The microstructure is located on the viscoelastic model which is simulated using Visco‐Pasternak platform. The size effects are assumed according to the theory of strain gradient including three‐length scale constants. The various theories of first‐order shear deformation beam theory (FSDBT), third‐order shear deformation beam theory (TSDBT), parabolic shear deformation beam theory (PSDBT), and exponential shear deformation beam theory (ESDBT) are utilized for driving the governing equations according to the Hamilton's principle. The motion final relations are solved by the differential quadrature method (DQM) for presenting the dynamic buckling area. The effects of different components such as volume percentage and distribution of GPLs, porosities, magnetic field of LPRE, applied voltage, FG index, structural damping, and geometric components of the micro sandwich beam on the dynamic stability reign (DIR) of the system are shown. The results with other researcher papers are compared. The results show that the DIR increases by applying a magnetic field to the LPRE layer. [ABSTRACT FROM AUTHOR]

In this paper, the nonlinear bending of functionally graded carbon nanotube‐reinforced composite (FG‐CNTRC) shell exposed to thermomechanical loading is perused. It is assumed that the composite shell is reinforced in the longitudinal axis and is also made from a polymeric matrix. Mechanical features of the constituents are obtained based on the modified rule of mixture, and they are considered to be temperature dependent (TD). Using the first‐order shear deformation shell theory (FSDT) as well as von Kármán type of geometrical nonlinearity, the equilibrium mathematical relations are derived. Utilizing the dynamic relaxation (DR) procedure combined with the central finite difference method, these mathematical relations are solved in diverse boundary conditions. Finally, roles of carbon nanotube (CNT) distributions, boundary conditions, shell radius, thickness‐to‐radius ratios, volume fraction of CNTs, mechanical loads, thermal gradient, and temperature dependency are examined on the results. From the numerical results, it can be inferred that in the shell with the CC boundary condition, the FG‐O distribution of nanotubes has the maximum deflection, and the lowest deflection belongs to the uniform distribution. However, in the SS boundary condition, the highest and lowest values of deflections are related to V and uniform distributions, respectively. [ABSTRACT FROM AUTHOR]

In the last decades, increasing traffic loads have led to higher requirements on the bearing capacity of existing and also new bridges. In particular, many bridge structures built in the 1960s and 1970s often contain less web reinforcement than the nowadays required minimum web reinforcement. In this context, the shear resistance under cyclic loading is of special interest. For this reason, experimental tests were conducted on prestressed concrete beams with and without shear reinforcement at the Institute of Structural Concrete of RWTH Aachen University within the last years to investigate the shear fatigue strength. The specimens were able to resist more load cycles than predicted by the approaches implemented in the Eurocodes for bridges. Based on the test results, design models for shear under cyclic loading should be reviewed and improved, especially with regard to the assessment of existing structures. This paper describes the recent tests on 20 I‐shaped prestressed beams with web reinforcement. [ABSTRACT FROM AUTHOR]

In this paper modal analysis is performed on a symmetric aluminum beam which is coated with functionally graded material containing porosities. A polynomial function is used to vary the density and elasticity through the thickness of the coating, while the effective elastic modulus and density are found with classical lamination theory. To achieve a truthful modeling the gradually changing mechanical properties of the coating are modeled as 25 layers of material, while each individual layer is isotropic and homogeneous. MATLAB is used to write a finite element code and Timoshenko beam elements are used to include shear deformation effects. To show the influences of crack location, crack depth, porosity and the polynomial function index on the natural beam frequencies a parametric study is conducted. Multiple boundary conditions were also considered and it was found that the natural frequency values were significantly affected by the studied parameters. [ABSTRACT FROM AUTHOR]

This paper presents a new theory for the shear capacity of reinforced concrete members without shear reinforcement. While recognizing that there are multiple failure mechanisms, the theory attributes the opening of a critical flexural shear crack as the lower bound of the shear capacity. It proposes that the shear displacement of an existing flexural crack can be used as the criterion for the unstable opening of the critical flexural shear crack. Based on the theory, the paper presents a simplified shear evaluation model. Compared with the current shear provisions in the design codes, the model is characterized by good accuracy and a solid physical background. It demonstrates a great flexibility for dealing with complex design conditions. As an example, the paper discusses the possibility of extending the theory to the shear resistance of higher-strength concrete. The suggested method provides a more logical and fluent transition from normal- to high-strength concrete and shows good agreement with experimental observations. [ABSTRACT FROM AUTHOR]

Innovative composite deck slab for railway bridges – experimental investigations on the fatigue resistance of the dowel strips A newly developed, extremely slender Steel‐Concrete‐Steel‐Composite (SCSC) plate is intended to serve as a deck slab for trough railway bridges. The multi‐layer structure of the plate consists of two steel cover plates with an unreinforced concrete core, hence the name of sandwich plate. Perforated shear connectors, welded alternately to only one of the outer steel plates, work together to ensure the transmission of the shear flow between the outer plates, by activation of diagonal concrete compression struts between adjacent dowel bars. After the examination of the static load bearing capacity in former research programs [1, 2], the current investigations are focussed on the fatigue behaviour of the SCSC plate, whereby the focus lies on the investigation of the relation between the amplitude of the traffic load and the bearable number of load cycles of the SCSC plate till crack initiation in the shear connectors. A detailed description of the numerical modelling of the SCSC plate using the Abaqus/Explicit [4] software and the calculation of the fatigue life of the dowel strips using the notch strain concept [5] are described in [6, 7]. This paper gives an overview of the planning, execution and evaluation of the experimental investigations and compares the experimental and the numerical results regarding the fatigue life of the dowel strip. [ABSTRACT FROM AUTHOR]

The existing punching shear design provisions according to current codes have either a semi‐empirical (e.g., Eurocode 2) or a more physical (e.g., Model Code 2010) background. Although the design procedures are very similar, the predicted punching shear capacities may differ significantly, depending on the background of the design provisions and the considered influences. Recent test series on reinforced concrete footings without shear reinforcement and with high amounts of shear reinforcement are available and can be used for the evaluation and improvement of the current provisions. Nevertheless, the evaluation of the code equations for the design of the shear reinforcement (failure inside the shear‐reinforced zone) is still not possible since systematic test series on footings with a varying amount of shear reinforcement have not yet been conducted. To investigate the punching shear behavior of reinforced concrete footings with low and medium amounts of shear reinforcement, three systematic test series (11 specimens) with stirrups as shear reinforcement were conducted. In the tests, the amount of shear reinforcement was varied by changing the stirrup diameter only. Further investigated influences were the shear span‐depth ratio and the effective depth. In this paper, the results of the test series are discussed and compared to the predictions according to Eurocode 2, Model Code 2010, and the draft of the second generation of Eurocode 2. [ABSTRACT FROM AUTHOR]

A precast wall‐type building is constructed by stacking wall panels and slabs. This paper presents a study of the in‐plane shear behavior of vertical grouted joints between precast panels. Thirteen jointed wall panel specimens were tested under direct shear. Based on the results, analytical expressions were developed to predict the shear load versus slip behavior. These can be used in computational models of precast wall type buildings, through modeling of shear springs between the panels. To demonstrate the application, a numerical analysis of an isolated jointed shear wall was performed. The wall was modeled for three cases, (a) monolithic wall, (b) two walls with a gap and (c) two walls with shear links. Based on non‐linear pushover analysis, it was demonstrated that the modeling of jointed walls using shear links reduces the conservatism inherent in a model neglecting the shear transfer across the joint. [ABSTRACT FROM AUTHOR]

We report Magnetospheric Multiscale observations of reconnection in a thin current sheet at the interface of interlinked flux tubes carried by converging reconnection jets at Earth's magnetopause. The ion skin depth‐scale width of the interface current sheet and the non‐frozen‐in ions indicate that Magnetospheric Multiscale crossed the reconnection layer near the X‐line, through the ion diffusion region. Significant pileup of the reconnecting component of the magnetic field in this and three other events on approach to the interface current sheet was accompanied by an increase in magnetic shear and decrease in Δβ, leading to conditions favorable for reconnection at the interface current sheet. The pileup also led to enhanced available magnetic energy per particle and strong electron heating. The observations shed light on the evolution and energy release in 3‐D systems with multiple reconnection sites. Plain Language Summary: The Earth and the solar wind magnetic fields interconnect through a process called magnetic reconnection. The newly reconnected magnetic field lines are strongly bent and accelerate particles, similar to a rubber band in a slingshot. In this paper we have used observations from NASA's Magnetospheric MultiScale spacecraft to investigate what happens when two of these slingshot‐like magnetic field lines move toward each other and get tangled up. We found that the two bent magnetic field lines tend to orient themselves perpendicular to each other as they become interlinked and stretched, similar to what rubber bands would do. This reorientation allows the interlinked magnetic fields to reconnect again, releasing part of the built‐up magnetic energy as strong electron heating. The results are important because they show how interlinked magnetic fields, which occur in many solar and astrophysics contexts, reconnect and produce enhanced electron heating, something that was not understood before. Key Points: Magnetic flux pileup observed upstream of reconnecting current sheet at the interface of converging reconnection jetsMagnetic flux pileup was accompanied by increase in magnetic shear and decrease in Δβ, leading to conditions favorable for reconnectionMagnetic flux pileup leads to enhanced available magnetic energy per particle and strong electron heating [ABSTRACT FROM AUTHOR]

This work describes the identification of the shear modulus of open cell polyurethane thermoformed auxetic foams from 3- and 4-point bending tests. The foams are incorporated in sandwich beams with carbon fibre/epoxy face skins, and benchmarked against similar sandwich structures made with the conventional counterpart open cell foam. Three types of beams are tested: one with auxetic foams, another type related to a conventional foam core with the same thickness of the auxetic porous materials, and a third type of beam consisting in conventional foam with a thickness corresponding to an iso-weight configuration to the auxetic specimen. The auxetic foam has a shear modulus 7% lower than the one of the bulk conventional specimens, but higher shear stresses at large deformations and a smoother strain stiffening response compared to the beams with the conventional thinner core. The paper also highlights the low shear wave speed of these auxetic foams compared to other porous polymers used in helmet and head protection applications, as well as potential uses of the quasi-zero-stiffness behavior here observed for the auxetic foam sandwich beam. [ABSTRACT FROM AUTHOR]

This paper presents a nonlinear viscoelastic model for polymer nanocomposites and the computed model response to large amplitude oscillatory shear flow. The model predicts the stress in a mixture of entangled polymer chains, with different convective constraint release (CCR) rates for free chains and nanoparticle‐attached chains, through an averaging scheme which is consistent with double reptation in the Marrucci–Ianniruberto constitutive equation. The nonlinear response of the mixture is evaluated both numerically in terms of Q and by an asymptotic analysis in terms of four frequency dependent parameters of medium amplitude oscillatory shear (MAOS) as well as the intrinsic nonlinearity parameter Q0. In the case of free polymer chains alone, the MAOS signatures are comparable to those of the Giesekus model with the notable difference of a minimum in the elastic parameter [e1] at De >1. The viscous nonlinear parameters of the mixture model depart significantly from those of the free chains, especially in mixtures where the CCR parameter for attached chains is larger than that for the free chains: [v1] has a prominent minimum and [v3] has a prominent maximum near De = 2/c, the low frequency plateau region, along with a higher Q0 compared to the matrix at all Deborah numbers. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019, 57, 62–76 The nonlinear viscoelastic response to large amplitude oscillatory shear of mixtures of entangled polymer chains—both unattached and attached to nanoparticle surfaces—has been modeled using a double reptation formulation of the Marrucci–Ianniruberto tube model. The mixture model developed here also incorporates different convective constraint release (CCR) parameters (βa > βf) for the two types of chains in nanoparticle filled polymer melts. The results show that entanglements between the particle attached chains lead to the greatest extent of nonlinearity. [ABSTRACT FROM AUTHOR]

In this paper, the mean stress relaxation behavior of simple Al‐alloy 2024‐T3 specimens and also the mean stress relaxation around the hole of cold expanded specimen are studied. The analyses are performed through the combination of the nonlinear isotropic hardening and Chaboche nonlinear kinematic hardening model accompanied by the results of experimental tests. The strain‐controlled axial tests are performed at two different strain amplitudes, while the stress‐controlled tests of cold expanded specimens are performed for three different imposed load amplitudes. The constitutive equations of the hardening model are coded as a UMAT subroutine in FORTRAN programming language and implemented in the commercial finite element code of ABAQUS. The accuracy of the hardening model has been proved in two steps: first by simulations of mean stress relaxation during the uniaxial strain‐controlled cyclic tests and second by simulation of strain ratcheting during the stress‐controlled cyclic loading. The stress and strain distributions after cold expansion process are examined as well as the mean stress relaxation due to cyclic loading. The results show the influences of imposed stress amplitude on increasing mean stress relaxation and also the effect of cold expansion level on reducing the mean stress relaxation. [ABSTRACT FROM AUTHOR]

The paper presents the results of 20 shear tests on full scale thermal insulating clay unit masonry walls. The types of units used (units with large chambers filled with mineral wool pads and units with small corings filled with mineral wool granulate) as well as the tested wall geometries and vertical loads are representative of the most common wall constructions currently used in housing in Germany. The aim of the investigations was the verification of the shear resistance of thermal insulating clay unit masonry under realistic conditions and comparison with the design rules in the codes and national technical approvals. The current design rules for clay unit masonry in DIN EN 1996‐1‐1/NA are rather conservative compared to the test results for thermal insulating units. [ABSTRACT FROM AUTHOR]

This paper presents the newly established ACI‐DAfStb database of shear tests on slender prestressed concrete beams without stirrups subjected to point loads. From the 574 collected tests 214 tests remain for the comparison with shear design approaches after the control and selection procedures were applied. The main features of these tests are described. Subsequently, these tests are used to perform evaluations of the shear design procedures of EC2, fib Model Code 2010, and ACI 318‐14. [ABSTRACT FROM AUTHOR]

This paper investigates the punching behavior of reinforced concrete flat slabs supported on rectangular columns under concentric loading. Based on the critical shear crack theory, a new model is proposed to determine the punching shear strength of slabs. In this model, a rectangular slab is replaced with an elliptical surface with the same area. The efficiency of the model is validated through comparisons made with experimental studies in the literature. Furthermore, results are compared with three different codes, namely, ACI, Eurocode 2, and FIB Model Code 2010. Finally, an alternative approach is introduced to facilitate the calculation of the punching shear capacity of slabs with column rectangularity considerations. For the experimental tests available in the literature, good shear strength predictions were obtained by the two proposed models. [ABSTRACT FROM AUTHOR]

Installation of building utilities often requires the creation of openings near existing slab–column connections. These openings reduce the concrete area that sustains the shear stresses, thus, the developed shear stresses are increased and contribute to the risk of punching shear failure. In this paper, nonlinear finite element analysis (FEA) using a previously calibrated coupled plasticity‐damage model for concrete is performed for interior slabs with square openings. An interior reinforced concrete flat slab without shear reinforcement, which was tested under gravity loading, is considered as the reference slab. The effect of the location and the size of the opening on the punching shear resistance are examined. Punching shear predictions according to ACI 318‐14, Eurocode 2‐2004, and fib Model Code 2010 are compared to the FEA results. Finally, probabilistic analyses using the Monte Carlo simulation are considered, and fragility analysis is performed to estimate the probability of the punching shear resistance related to the size and distance of the opening. [ABSTRACT FROM AUTHOR]

In recent years, the cosα method has attracted engineers as a new method of X‐ray stress measurement using the whole Debye–Scherrer (D–S) ring recorded on a two‐dimensional detector. The principle of the cosα method was first proposed by Taira, Tanaka & Yamasaki [J. Soc. Mater. Sci. Jpn, (1978), 27, 251–256] for in‐plane biaxial stress analysis and later extended by Sasaki and co‐workers [Sasaki & Hirose (1995). Trans. Jpn Soc. Mech. Eng. Part A, 61, 2288–2295; Sasaki, Takahashi, Sasaki & Kobayashi (2009). Trans. Jpn Soc. Mech. Eng. Part A, 75, 219–227] to the triaxial state of stress. The method proposed by Sasaki and co‐workers utilizes several D–S rings taken at different incident angles of X‐rays in order to determine triaxial stresses. In the present paper, the cosα method was applied to measure triaxial residual stresses of uni‐directionally machined surfaces of a carbon steel made by grinding, milling and planing. A recommended procedure for experimental measurements of in‐plane normal and shear stresses and out‐of‐plane shear stress is proposed, together with a new method for determination of the out‐of‐plane normal stress. The tilt angle of X‐ray incidence for stress determination is recommended to be larger than 35°, where the stress constant is low and the stress sensitivity is high. Normal incidence is recommended for the determination of out‐of‐plane shear stresses. The out‐of‐plane shear stress along the cutting direction was characteristic of uni‐directionally machined surfaces and increased with cutting severity in the order of grinding, milling and planing. The in‐plane normal stress was compressive for ground and milled surfaces, and the magnitude of compression was larger in the direction perpendicular to the cutting direction. On the basis of the stress values measured under different tilt angles, it is suggested that the magnitude of in‐plane normal residual stress increases near the surface. The out‐of‐plane normal stress determined by the new method indicated a small compression. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, an analytical study is carried out on the work‐hardening, elastic‐plastic stress distributions in a cracked body under antiplane shear deformation. A modified Ramberg‐Osgood law is introduced to describe the material behaviour, and stress and strain fields are derived in closed form. Compared with the conventional Ramberg‐Osgood formulation, the new law includes the effect of a new parameter, κ, which allows the transition from the ideally elastic behaviour (low stress regime) to the power law behaviour (large stress regime) to be controlled, thus providing 1 more degree of freedom to better fit the actual behaviour of engineering materials. A discussion is carried out on the features of stresses and strains close to and far away from the crack tip. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, the bending singularities of a notched plate are investigated through the finite element method. The computed singular parameters, including the singularity orders and associated corner functions, are compared with those of classical plate theory and first‐order shear deformation plate theory (FSDPT); the comparisons demonstrate the inaccuracy of the boundary conditions in classical plate theory. The thickness effects are then investigated through the finite element method. The results show that although the singularity parameters computed by finite element agree with those of the FSDPT in the interior of the plate, the FSDPT is not applicable at the notch tip on the top or bottom surface because of substantial free surface effects. For a very thin plate, the inconsistence in the comparison slightly increases because of the free surface effects. [ABSTRACT FROM AUTHOR]

In this paper, a numerical model to predict flow-induced shear failure along pre-existing fractures is presented. The framework is based on a discrete fracture representation embedded in a continuum describing the damaged matrix. A finite volume method is used to compute both flow and mechanical equilibrium, whereas specifically tailored basis functions are used to account for the physics at discontinuities. The failure criterion is based on a maximum shear strength limit, which changes with varying compressive stress on the fracture manifold. The displacements along fracture manifolds are obtained such that force balance is achieved under conditions, where shear stress of the failing fracture segment is constrained to the maximum shear strength at the segment. Simultaneously, the fluid pressure is computed independently of the shear slip. A relaxation model approach is used to obtain the maximum shear limit on the fracture manifold, which leads to grid convergence. [ABSTRACT FROM AUTHOR]

The paper presents the results of an experimental program carried out on 96 concrete pullout specimens prepared with natural and recycled aggregates using 10 and 12 mm diameter deformed steel bars. Steel rebars were concentrically embedded in pullout specimens with two embedded length of 5 and 10 times the rebar diameter. The present work includes six recycled concrete aggregate mixtures and two conventional concrete mixtures with C25/30 and C35/45 target class of compressive strength and S4 class of workability. For both series, specimens were fabricated with different incorporation ratios of fine and coarse recycled aggregates and only coarse recycled aggregates. Tensile load was applied gradually until the pullout failure occurred and the slip between the rebar and concrete was measured at the free and loaded ends for each loading level. Furthermore, systematic observations of failure surface have been made at both macroscopic and microscopic scales. Test results showed that for the same class of compressive strength the bond strength and related failure mechanisms remain very close and the obtained values are, at least, four times higher than the predicted values by Eurocode 2. The experimental results of this study, together with an extensive number of results reported in the literature, were used to describe the variation of bond strength with concrete compressive strength, embedded length, and concrete cover. In addition, an analytical bond-slip relationship is proposed and the parameters of bond-slip law were calibrated by an optimization algorithm. [ABSTRACT FROM AUTHOR]

T-beams are acknowledged as economic and efficient structural members widely used for floor slab construction systems. In many cases, according to practice in some countries, the beams do not present transverse reinforcement, and their shear strength is governing for dimensioning the width of the web. Although experimental investigations have shown that the presence of the compression flange enhances the shear capacity with respect to equivalent rectangular cross sections, most current design codes neglect this phenomenon, which leads to the overdesign of these members. In this paper, the role of the compression flange of slender T-beams with concentrated loads is investigated with reference to its influence on the shape of the critical shear crack and to the associated shear transfer actions (STA) of the beam. The flanges are considered elements that allow the smearing of applied loads over a certain length of the web. This consideration, in combination with the mechanical model of the Critical Shear Crack Theory ( CSCT), allows a consistent treatment of the phenomenon and leads to simple design expressions accounting for the role of flanges. The results of the proposed model are compared together with design codes (Model Code 2010, Eurocode 2, and ACI 318-11) and other shear design approaches to a database of 239 beams on T-shaped members. The comparison shows that the role of flanges is finely accounted with the proposal based on the CSCT, leading to consistent agreement and to strength predictions that are more suitable for design purposes than the other investigated design models. [ABSTRACT FROM AUTHOR]

A shearing interference microscope using a Savart prism as the shear plate is proposed for inspecting step-heights. Where the light beam propagates through the Savart prism and microscopic system to illuminate the sample, it then turns back to re-pass through the Savart prism and microscopic system to generate a shearing interference pattern on the camera. Two measurement modes, phase-shifting and phase-scanning, can be utilized to determine the depths of the step-heights on the sample. The first mode, which employs a narrowband source, is based on the five-step phase-shifting algorithm and has a measurement range of a quarter-wavelength. The second mode, which adopts a broadband source, is based on peak-intensity identification technology and has a measurement range up to a few micrometres. This paper is to introduce the configuration and measurement theory of this microscope, perform a setup used to implement it, and present the experimental results from the uses of the setup. The results not only verify the validity but also confirm the high measurement repeatability of the proposed microscope. [ABSTRACT FROM AUTHOR]

In the authors' previous study, the dual potential capacity model (DPCM) was proposed to evaluate the shear strengths of reinforced concrete (RC) members, in which the shear contributions of both the cracked tension zone and the compression zone are considered. In this paper, the main concept and formulations of the proposed DPCM were briefly introduced, and the simplified DPCM was developed for the practical application of the proposed model. A total of 1019 data sets of shear test results on RC members were collected for detailed verifications of the detailed and simplified DPCM. The verification results demonstrated that the proposed models can appropriately assess the effects of key influential factors including compressive strength of concrete, shear span-to-depth ratio, size of coarse aggregate, sizes of members, and shear reinforcement on the shear strengths of RC members. [ABSTRACT FROM AUTHOR]

The first step in the design of a structure is the definition of the geometry. This process includes the definition of the depth of slabs and beams. The depth of a flexural member is often determined by control of deflections, which can only be checked in detail at an advanced stage of the project. In order to optimize the design process, it is therefore very important to choose well the span-to-depth ratio at the beginning. In order to achieve this task in an easy manner, a lower limit to the slenderness of the beams in terms of span divided by the effective depth is proposed in most major codes. However, current proposals are rather coarse and are not necessarily on the safe side. In this paper, a new formulation for the slenderness limits, based on the physics of the problem, is presented. This formulation includes the effect of the composition of the load (live load to total load ratio) as well as the possibility of using different limits to maximum deflection and considering different, more general, support conditions. It is therefore more complete and has a larger application field than current proposals. [ABSTRACT FROM AUTHOR]

This paper presents a comprehensive experimental study and detailed mechanistic interpretations of the shear deformation of three-dimensional (3D) reinforcements. Six types of 3D angle interlock glass fiber preforms (3DAP) were fabricated using a range of weave parameters including the fabric density, fabric layer, and yarn linear density. A modified picture frame was developed to ensure a pure shear load during the test. Through a series of comprehensive tests, our results demonstrated that the fabric density played a key role in the mechanical properties of 3DAP and that the reinforcements with low fabric density and yarn linear density were easy to shear. The shear deformation mechanism was analyzed based on the meso-structure. It is expected that this research will provide preliminary work for building a theoretical model of 3D woven preform. POLYM. COMPOS., 38:244-251, 2017. © 2015 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

Load bearing behaviour of layered ceiling elements made of regular and porous lightweight concrete Lightweight and efficiently bearing steel reinforced elements may be achieved through the application of regular and porous concrete in a three-layer cross-section. While exterior layers of higher strength carry bending moments, a lightweight core layer material holds up to shear stresses. In order to quantify the potential of this construction method, the bearing behaviour of 18 layered ceiling elements with six different geometries was investigated. The goals were both to identify different failure modes, as well as evaluate the suitability of commonly used calculation procedures. The following paper shows that an optimal usage of cross-sections of ceiling elements can already achieved by using concrete with strengths between 5 MN/m2 and 20 MN/m2. The efficiently bearing elements are characterized by the fact, that both the concrete, the reinforcing steel and the layer's interface are highly stressed both under pressure and tension. The tested specimens showed both a tensile bending and interface failure with a partly very high utilization of the flexural compressive zone. [ABSTRACT FROM AUTHOR]

Purpose: Features extracted from axial-shear strain images of breast masses have been previously utilized to differentiate and classify benign from malignant breast masses. In this paper, we compare shear strain patterns exhibited by both the full-shear (axial and lateral component) versus only the axial-shear strain component for differentiating between bound masses (malignant) when compared to unbound masses (benign). Methods: We examine different breast mass characteristics such as mass shape, asymmetric location of masses, stiffness variations, and mass bonding characteristics to background tissue to assess their impact on shear strain patterns generated due to a uniaxial applied deformation. Two-dimensional finite element simulations of both circular and elliptical inclusions embedded within a uniform background were utilized. Different degrees of bonding were characterized using friction coefficient values ranging from 0.01 to 100 denoting loosely bound to firmly bound masses. Single-inclusion tissue-mimicking phantoms mimicking firmly bound and loosely bound ellipsoidal masses oriented at four different angles to the applied deformation were studied to corroborate the mass differentiation performance. Results: Our results indicate that the normalized axial-shear strain and full-shear strain area features are larger for bound when compared to unbound masses. A higher stiffness ratio or contrast between the inclusion and background also improves differentiation. Larger applied deformations reduce the discrimination performance for masses with friction coefficients lower than 0.4, due to increased mass slippage with applied deformations. Potential errors with the use of these features would occur for unbound inclusions at larger applied deformations and for asymmetric mass positions within the background normal tissue. Conclusions: Finite element and tissue-mimicking phantom results demonstrate the feasibility of utilizing both the normalized axial-shear and full-shear strain area features to classify breast masses. Differentiation between bound or unbound masses was not affected by the mass size or shape for masses where the applied deformation is normal to the mass surface. Shear strain patterns vary significantly especially within unbound masses, when the mass surface is not normal to the applied deformation. Discrimination performance for unbound masses was improved by utilizing only the normalized shear strain area patterns located outside the mass as illustrated in this paper. [ABSTRACT FROM AUTHOR]