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Through the improvement of supporting structure and the utilization of the interaction between surrounding rock and supporting structure, the synergistic system of energy-absorbing yielding anti-impact supporting structure and surrounding rock is established. The process of energy absorption device, energy-absorbing yielding anti-impact supporting structure and synergistic system under impact is simulated to analyze the properties of them. The following conclusions could be drawn. The deformation and yielding process under compression of energy absorption device is divided into five stages. Compared with the traditional supporting structure, the energy-absorbing yielding anti-impact supporting structure has the reaction force with lower value and smaller fluctuation range before the deformation of the energy absorption device reaches the third ascending section. The synergy between surrounding rock and supporting structure plays an important role in roadway support. Compared with the supporting structure without surrounding rock, the reaction force of the supporting structure in the synergistic system is lower, and a stationary stage is added in the early stage of the reaction force curve. [ABSTRACT FROM AUTHOR]

Abstract: A nanoscale quasi-continuum (QC) model for exploring the mechanical properties of human erythrocyte/red blood cell (RBC) membranes is presented in this paper. The so-called higher order Cauchy–Born rule (HCB rule) is utilized as the linkage between the deformation of the spectrin network/cytoskeleton and that of the corresponding equivalent continuum. By incorporating the second order deformation gradients into kinematic description, the resulting QC model can capture the curvature effect of nanoscale membranes accurately in a geometrically consistent way. Based on the proposed QC model, a variationally consistent meshless computational scheme is developed for simulating the finite deformation of human erythrocyte/RBCs. The obtained deformation and wrinkling patterns are in good agreement with those from the existing experiments. [Copyright &y& Elsevier]

Abstract: In the present study, a meshless computational framework for simulating the large deformation behaviors of single-walled carbon nanotubes (SWCNTs) at finite non-zero temperatures is established based on the so-called temperature-related higher order Cauchy-Born rule (THCB rule) where the second-order deformation gradient is involved in the kinematic description of the deformation of SWCNTs. The Helmholtz free energy is used as the thermodynamic potential and the local harmonic approximation (LHA) is adopted to construct the nanoscale quasi-continuum constitutive model. The proposed numerical approach is then applied to four numerical examples under different loading conditions. It is found that the results obtained by the proposed numerical framework agree well with those from molecular dynamics simulations. [Copyright &y& Elsevier]

Abstract: In previous work about axisymmetric adhesive contact on power-law graded elastic materials, the contact interface was often assumed to be frictionless, which is, however, not always the case in practical applications. In order to elucidate the effect of friction and the coupling between normal and tangential deformations, in the present paper, the problem of a rigid punch with a parabolic shape in non-slipping adhesive contact with a power-law graded half-space is studied analytically via singular integral equation method. A series of closed-form analytical solutions, which include the frictionless and homogeneous solutions as special cases, are obtained. Our results show that, compared with the frictionless case, the interfacial friction tends to reduce the contact area and the indentation depth during adhesion. The magnitude of the coupling effect depends on both the Poisson ratio and the gradient exponent of the half-space. This effect vanishes for homogeneous incompressible as well as for linearly graded materials but becomes significant for auxetic materials with negative Poisson’s ratio. Furthermore, influence of mode mixity on the adhesive behavior of power-law graded materials, which was seldom touched in literature, is discussed in details. [Copyright &y& Elsevier]

Abstract: Nanoscale twin boundaries play a significant role in the yield behavior of nanowires. They serve as both a source of dislocation nucleation and a generator of the repulsive force which acts against the nucleation of dislocations. In the present paper molecular dynamics (MD) simulations are performed to investigate the tensile deformation of twinned gold nanowires (NWs) of finite length. Emphasis is placed on competing mechanisms in the initial yield of nanowires: dislocation source number vs. repulsive force, both of which are controlled by the twin boundary spacing. The simulation results reveal that with decreasing twin boundary spacing there is a transition from softening to strengthening due to a change in the dominant mechanism of plastic deformation. An analytical model based on kinetic rate theory is also established to provide an insight into the competing mechanisms indicated by the simulation results. [Copyright &y& Elsevier]

A temperature-related multiscale quasi-continuum (QC) model is presented herein for the investigation of the finite deformation behaviors, especially buckling and post-buckling, of open-tip single-walled carbon nanocones (SWCNCs) in thermal environments. The hyper-elastic constitutive model is established with the use of so-called temperature-related higher-order Cauchy–Born (THCB) rule as the kinematic description for the deformation of SWCNCs. The corresponding meshless computational scheme is developed to accomplish the numerical simulation of the deformation responses of SWCNCs. The numerical results reveal that the present approach is effective and efficient for the prediction of the buckling behaviors of SWCNCs at finite temperature. It is found that the buckling and post-buckling of SWCNCs are strongly dependent on the rotation angle of cutting lines, the top radius, the height and the apex angle. The mechanical properties and buckling of SWCNCs with large top radius and apex angle are close to those of graphene. [ABSTRACT FROM AUTHOR]

Tension–compression asymmetry, thermal-mechanical coupling, and finite deformation effects are common characters of many biological materials and engineering structures. By introducing different elastic constants under tension and compression, a thermo-mechanical bi-modulus constitutive model and a subsequent efficient computational analysis framework are proposed in the finite deformation regime. After we validate the convergence, accuracy, and robustness of the algorithm, we investigate the mechanical behavior of human brain tissue under varying intracranial pressure and temperature. Furthermore, with the use of the proposed bi-modulus thermoelasticity model, the classic tension-field theory is regularized, and wrinkling region and its evolution in membranes under thermomechanical loads can be effectively predicted, as an alternative to the computationally intensive post-buckling analyses. • A constitutive law accounting for TCA, thermal-mechanical coupling, and finite deformation effects is proposed. • An efficient iterative method for bi-modulus thermoelastic structures is developed. • Thermoelastic responses of human brain tissue is simulated. • Wrinkling regions of membranes in thermo-mechanical environment are efficiently predicted. [ABSTRACT FROM AUTHOR]

In this work, an explicit three-dimensional (3D) topology optimization approach is presented for multi-material composite structures accounting the finite deformation effect. The proposed method employs different sets of 3D Moving Morphable Voids (MMVs) to identify each phase material, resulting in explicit geometric descriptions of the optimized composite structures and a reduction in the number of design variables. The decoupling between the topology description and finite element analysis of composite structures enables the removal of redundant degrees of freedom, thereby mitigating the convergence issue of finite deformation analysis caused by low-density elements and leading to significant computational savings. Numerical experiments of composite structures with two- and three-phase materials are optimized to validate the accuracy and efficiency of the proposed method. The results demonstrate that, under finite deformation, the distribution of each phase material in optimized 3D composite structures is significantly affected by the amplitude of external loads, and the optimized layout could be quite different from its counterpart under small deformation assumption. • An explicit 3D topology optimization method is developed for composite structures with finite deformation. • The redundant DOFs removal technique is extended to solve the convergence issue and improve efficiency of FEA. • Optimized structures composed of 2- and 3-phase materials illustrate the effectiveness of the proposed approach. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Specimens with various geometries to achieve multiaxial stress states. • The twins and stress-states play a key role in the voids nucleation and deformation. • The twins provide more sites for void nucleation and constrain void shape change. • The voids can coalesce to reach large size under the low stress-triaxiality. Abstract In situ scanning electron microscope (SEM) investigation is carried out on high-entropy alloy (HEA) specimen with various geometries to realize the multi-axial stress states. The dimple structure on the fracture surface is quantified and the nucleation of void is examined. The deformation twins can provide more sites for void nucleation and constrain shape change of the voids. Even under the low stress-triaxiality, the void can coalesce to reach large size accompanying twinning. The evolution of void size and density deduced from the fractograph is important to quantify ductile fracture of HEA. [ABSTRACT FROM AUTHOR]

Abstract In the present work, we intend to show how to perform structural topology optimization under finite deformation with the use of explicit geometry description. To this end, a Moving Morphable Void (MMV)-based approach is developed. Compared to existing approaches in the literature, the advantages of the proposed method consist in the fact that it can not only reduce the number of design variables substantially, but also alleviate the convergence problems associated with nonlinear structural response analysis significantly. Furthermore, smooth structural boundaries with explicit B-spline descriptions, which are always desirable for CAD/CAE softwares, can also be obtained straightforwardly via this approach. Numerical examples provided demonstrate the effectiveness of the proposed approach. [ABSTRACT FROM AUTHOR]

More precise modeling on ductile fracture of metals at the scale from micron to meter is still urgently needed in many engineering applications. Due to the variety of metal and its alloys, a lack of understanding on the mechanisms and quantitative experimental data impede building and assessing mechanics models for ductile fracture at different length scales. In this paper, in situ tensile tests are carried out in Transmission Electronic Microscope (TEM) on copper, high entropy alloy and aluminium alloy. We examine the full process of void growth and coalescence of neighboring voids under the view of the TEM. Nanotwins on the ligament between neighboring voids lead to a new coalescence mechanism for copper and high entropy alloy. Necking and shearing coalescence of aluminium alloys are clearly illustrated, which are demonstrated by the samples with manually drilled hole before by SEM (Scanning Electronic Microscope). The quantitative data on the evolution of void geometry are recorded, and are then used to verify the existing coalescence models in the literature. It is found that the McClintock model for void coalescence provides a better prediction than the Brown-Embury model (including the modified Brown-Embury model). A multiscale homogenization framework for in situ experiments can be further used to extract the stress state around the voids, and explaining the importance of stress-state on cavitation/nucleation, growth and coalescence of voids. [ABSTRACT FROM AUTHOR]

Abstract: A cohesive zone model for two-dimensional adhesive contact between elastic cylinders is developed by extending the double-Hertz model of Greenwood and Johnson (1998). In this model, the adhesive force within the cohesive zone is described by the difference between two Hertzian pressure distributions of different contact widths. Closed-form analytical solutions are obtained for the interfacial traction, deformation field and the equilibrium relation among applied load, contact half-width and the size of cohesive zone. Based on these results, a complete transition between the JKR and the Hertz type contact models is captured by defining a dimensionless transition parameter μ, which governs the range of applicability of different models. The proposed model and the corresponding analytical results can serve as an alternative cohesive zone solution to the two-dimensional adhesive cylindrical contact. [Copyright &y& Elsevier]