今日更新：International Journal of Solids and Structures 1 篇，Journal of the Mechanics and Physics of Solids 2 篇，Mechanics of Materials 5 篇，International Journal of Plasticity 1 篇，Thin-Walled Structures 5 篇
International Journal of Solids and Structures
Hybrid intelligent framework for designing band gap-rich 2D metamaterials
Mohamed Shendy, Mohammad A. Jaradat, Maen Alkhader, Bassam A. Abu-Nabah, T.A. Venkatesh
doi:10.1016/j.ijsolstr.2024.113053
设计富带隙二维超材料的混合智能框架
An artificial intelligence machine learning-based design framework is proposed to design lattice-based metamaterials with hexagonal symmetry that deliver wide band gaps at user-desired frequency ranges between 0 and 1000 kHz. The design approach starts by selecting a traditional, easy-to-manufacture parent lattice-based material that does not necessarily exhibit wide or functional band gaps. Subsequently, the parent lattice is transformed into a band-gap-rich lattice by superposing periodic triangular-shaped perturbations (i.e., zigzag-sine-based curvatures) with controllable frequencies and magnitudes on its ligaments. Finally, the frequency and magnitude parameters needed to deliver a specific band gap between 0 and 1000 kHz are determined using a hybrid intelligent framework, developed based on an Adaptive Neuro-Fuzzy Inference Systems (ANFIS). The ANFIS network integrates fuzzy logic expert models and artificial neural networks’ machine learning capabilities. Such a hybrid network is known for its ability to model strongly nonlinear and complex data. The data used in training the ANFIS models is generated using parametric finite element-based simulations where band gaps corresponding to a wide range of perturbation frequencies and magnitudes are computationally determined. The parametric study showed a nonlinear and complex topology-band gap characteristic relation; however, the Adaptive Neuro-Fuzzy Inference System (ANFIS) proved capable of modeling the observed complex topology-band gap behavior efficiently. The accuracy of the ANFIS models exceeded 99 % in several design ranges (i.e., perturbation parameters ranges). These were designated as high-accuracy design regions and were highlighted in the proposed design approach. Using multiple case studies with different band gap requirements, the ANFIS-based design framework proved effective in delivering customized lattice-based metamaterials with user-defined band gap frequencies.
A generalized strain model for spectral rate-dependent constitutive equation of transversely isotropic electro-viscoelastic solids
M.H.B.M. Shariff, R. Bustamante, J. Merodio
doi:10.1016/j.jmps.2024.105838
横向各向同性电粘弹性固体谱率相关本构方程的广义应变模型
We model the constitutive equation for nonlinear electro-viscoelastic transversely isotropic solids with short term memory via a generalized strain method, where the method is a change with respect to the methods that have been done in the last decades regarding mechanics of nonlinear solids. Our generalized strain model uses spectral invariants with a clear physical interpretation and hence they are attractive for use in experiments. The constitutive equation contains single-variable functions, which are easy to deal with when compared to multivariable functions. The effects of viscosity and electric fields are analysed via the boundary value problem results. The efficacy the proposed prototype is scrutinized by comparing our theory with experimental data.
Rayleigh surface waves of extremal elastic materials
Yu Wei, Yi Chen, Wen Cheng, Xiaoning Liu, Gengkai Hu
doi:10.1016/j.jmps.2024.105842
极端弹性材料的瑞利表面波
Extremal elastic materials here refer to a specific class of elastic materials whose elastic matrices exhibit one or more zero eigenvalues, resulting in soft deformation modes that, in principle, cost no energy. They can be approximated through artificially designed solid microstructures. Extremal elastic materials have exotic bulk wave properties unavailable with conventional solids due to the soft modes, offering unprecedented opportunities for manipulating bulk waves, e.g., acting as phonon polarizers for elastic waves or invisibility cloaks for underwater acoustic waves. Despite their potential, Rayleigh surface waves, crucially linked to bulk wave behaviors of such extremal elastic materials, have largely remained unexplored so far. In this paper, we theoretically investigate the propagation of Rayleigh waves in extremal elastic materials based on continuum theory and verify our findings with designed microstructure metamaterials based on pantographic structures. Dispersion relations and polarizations of Rayleigh waves in extremal elastic materials are derived, and the impact of higher order gradient effects is also investigated by using strain gradient theory. This study provides a continuum model for exploring surface waves in extremal elastic materials and may stimulate applications of extremal elastic materials for controlling surface waves.
Spatio-temporal physics-informed neural networks to solve boundary value problems for classical and gradient-enhanced continua
Duc-Vinh Nguyen, Mohamed Jebahi, Francisco Chinesta
doi:10.1016/j.mechmat.2024.105141
基于时空物理的神经网络解决经典连续体和梯度增强连续体的边值问题
Recent advances have prominently highlighted physics informed neural networks (PINNs) as an efficient methodology for solving partial differential equations (PDEs). The present paper proposes a proof of concept exploring the use of PINNs as an alternative to finite element (FE) solvers in both classical and gradient-enhanced solid mechanics. To this end, spatio-temporal PINNs are designed to represent continuous solutions of boundary value problems within spatio-temporal space. These PINNs directly incorporate the equilibrium and constitutive equations in their differential and rate forms, bypassing the requirement for incremental implementation. This simplifies application of PINNs to solve complex mechanical problems, particularly those involved in the context of gradient-enhanced continua. Moreover, traditional meshing is no longer required as it is replaced by a point cloud, making it possible to overcome meshing drawbacks. The results of this investigation prove the effectiveness of the proposed methodology, especially with regards to non-monotonic loading conditions and irreversible plastic deformation. Compared to classical FE approaches, the proposed spatio-temporal PINNs are more readily applied to complex problems, which are tackled in their raw form. This is especially true for gradient-enhanced continuum problems, where there is no need to introduce additional degrees of freedom as in classical FE approaches. However, PINNs training generally requires more computation time, a challenge that can be mitigated by employing the concept of transfer learning as shown in this paper. This concept, which is very useful when performing parametric studies, involves applying knowledge grained from solving one problem to another different but related one. The use of PINNs as mechanical solvers is shown to be highly promising in the forthcoming era, where advancements in GPU technology can further enhance their performance in terms of computation time.
Oligo-cyclic Loading-induced Evolution of Stress Distribution and Apparent Amorphous Modulus in Lamellar Stacks of High-density Polyethylene
Hang GUO, Renaud G. RINALDI, Sourour TAYAKOUT, Morgane BROUDIN, Olivier LAME
doi:10.1016/j.mechmat.2024.105137
低循环加载诱导高密度聚乙烯片层堆应力分布和表观非晶态模量的演化
Assessing the resistance of high-density polyethylene (HDPE) against earthquake-like loads involves understanding the changes in structure and properties induced by oligo-cyclic loading at various length scales. To study the evolution of stress distribution and intrinsic properties within lamellar stacks from pristine to oligo-cyclic loading pre-conditioned materials, simultaneous in-situ SAXS/WAXS measurements were performed. During the elastic deformation of each pristine and preconditioned sample, crystal strain was tracked using the in-situ WAXS technique. Based on the established elastic tensor of the crystalline structure in polyethylene, we calculated the microscopic stress values within crystalline lamellae. In the pristine sample, lamellar stacks exhibit closely series-like coupling in the equatorial region and parallel-like coupling in the polar region of the spherulite. In the pre-conditioned sample, stress is primarily concentrated in the intra-fibrillar region, where the crystalline and amorphous phases are series-coupled, and strong strain concentration occurs in the inter-fibrillar region. By combining the local strain in the amorphous layer within the lamellar stacks in the equatorial region of the spherulite and the intra-fibrillar region with series-coupled lamellar stacks, measured by in-situ SAXS tests, the apparent amorphous modulus at the lamellar stack scale can be determined. This modulus changes from 71-106 MPa in the equatorial region of pristine spherulites to a notable 2000-7000 MPa in the intra-fibrillar region under the influence of oligo-cyclic pre-loading. Importantly, this apparent modulus is affected by both crystallization conditions and molecular structure, with molecular parameters exerting the primary influence.
Planar metamaterial with sign-switching Poisson’s ratio based on self-contact slits
Ying Gao, Qingxu Liu, Yuntong Du, Xingyu Wei, Hong Hu, Zhengong Zhou, Jian Xiong
doi:10.1016/j.mechmat.2024.105138
基于自接触狭缝的符号开关泊松比平面超材料
The emergence of artificial metamaterials not only enables many physical and mechanical properties that are not accessible by natural materials but also provides people with new opportunities to break down particular limitations in engineering. In this work, a new metamaterial characterized by unusual sign-switching Poisson’s ratio is introduced. Different from all conventional and auxetic materials that exhibit reversed lateral deformation under tension and compression, the new metamaterial proposed here always expands in the direction orthogonal to the applied load. Our design relies on a planar construction perforated with periodically distributed self-contact slits. The mechanical responses of the proposed metamaterial subjected to uniaxially tensile, compressive, and bending loads are systematically investigated using a combination of numerical simulations and experimental tests. It is found that a lateral expansion effect is also induced for the bending test. Based on its unique property, a new concept of implant is developed to reduce the risk of loosening after total hip replacement. The demonstrative example highlights the potential applications of the new metamaterial in various fastening systems.
Hierarchical elastoplasticity of cortical bone: Observations, mathematical modeling, validation
Valentina Kumbolder, Claire Morin, Stefan Scheiner, Christian Hellmich
doi:10.1016/j.mechmat.2024.105140
皮质骨的分层弹塑性:观察，数学建模，验证
Motivated by the water layer-coated nanoscale bone mineral crystals and the elastoplastic behavior seen at the extracellular scale, we develop a six-step hierarchical micromechanics model for the elastoplasticity of cortical bone. For that purpose, the Eshelby problem-based concentration-influence tensor concept is generalized for a multi-scale situation, quantifying the mechanical interaction between elastic and plastic strains between material phases across six orders of magnitude in observation scale. This hierarchical interaction scheme is complemented by non-associated Mohr–Coulomb plasticity assigned to the mineral crystal phases, and a return mapping algorithm which adapts classical computational mechanics approaches for the realm of semi-analytical continuum micromechanics. Founded on elastic and strength properties of molecular collagen and hydroxyapatite, the model passes experimental validation against ultrasonic and quasi-static tests at the extrafibrillar, extracellular, extravascular, and cortical observation scales, across different tissue and species. It reveals cortical bone strength to increase nonlinearly with the vascular porosity, and to depend bi-linearly on the extracellular mass density, while elucidating plastic spreading events at the nanocrystal scale, which are fundamentally different in tensile and compressive loading.
A novel three dimensional failure criterion for quasi-brittle materials based on multi-scale damage approach
Lu Ren, Zhao-Min Lv, Fu-Jun Niu, Zi-Peng Qin, Lun-Yang Zhao
doi:10.1016/j.mechmat.2024.105142
基于多尺度损伤方法的准脆性材料三维破坏准则
In this paper, we propose a novel three-dimensional micromechanics-based failure criterion to assess the load-bearing capacity of quasi-brittle materials under complex multiaxial stress conditions. This criterion not only inherits benefits of the multi-scale friction-damage coupling modeling approach but also accounts for the effect of the intermediate principal stress. Physically, the initiation and propagation of microcracks contribute to the damage, and the failure of the material ultimately occurs due to the unstable growth of microcracks. Simultaneously, plastic deformation, which results from frictional sliding along microcracks, is intimately coupled with the damage process. Employing friction-damage coupling up-scale analyses and introducing a novel parabolic local frictional law, we derive a new nonlinear compression meridian criterion within the upscaling framework. Moreover, by incorporating a Lode dependence function, this criterion effectively addresses variations in strength induced by the intermediate principal stress. To validate this criterion, we utilize data from triaxial compression, triaxial extension, and true triaxial tests conducted on various rock materials and concrete, all of which demonstrate excellent agreement.
An anisotropic damage visco-hyperelastic model for multiaxial stress-strain response and energy dissipation in filled rubber
Lionel Ogouari, Qiang Guo, Fahmi Zaïri, Thanh-Tam Mai, Kenji Urayama
doi:10.1016/j.ijplas.2024.104111
填充橡胶多轴应力-应变响应及能量耗散的各向异性损伤粘-超弹性模型
In this article, we introduce a novel physically-based anisotropic damage visco-hyperelastic model designed to predict the history-dependent inelastic behavior of multiaxially stretched filled rubber. The model integrates both the anisotropic Mullins effect and intrinsic viscosity through the consideration of internal physics, represented by two distinct networks: an elastic ground network and a superimposed viscous network. The rupture of molecular bonds within the elastic network chain backbone is modeled using statistical mechanics, while the effects of anisotropy-induced chain orientation at the upper scale are addressed through a microsphere-based scale transition method. The intrinsic viscosity is represented by the viscous network, which is governed by time-dependent equations to account for the viscous overstress. The influence of fillers is captured through the concept of strain amplification, applied to the two networks within the rubber matrix. The effectiveness of the model in capturing the biaxial behavior of filled rubber is evaluated by comparing its outputs with experimental data from a filled rubber system. This assessment specifically considers the impact of pre-stretching under various loading conditions and across a wide range of filler concentrations. Notably, it successfully predicts anisotropic stress-strain response and energy dissipation, and the coupled effects of damage and viscosity.
Effect of orbital hybridization inspired tessellation strategy on the mechanical properties of lattice structures
Mohit Sood, Chang Mou Wu, Chih Wei Tang
doi:10.1016/j.tws.2024.112396
轨道杂化激发镶嵌策略对晶格结构力学性能的影响
The work presents a noble orbital hybridization-inspired tessellation approach for lattice structures, which may modify the characteristics of a lattice. The strategy organizing lattice unit cells according to sp, sp2, sp3, and sp3d2 hybridization patterns. Material extrusion (MEX) was employed to manufacture the tessellated structures, and it was investigated using static and dynamic loads. The sp3-inspired tessellation displayed the greatest energy absorption and revealed two separate failure modes: layer-wise and layer-coupled cell failure. The sp3-inspired tessellated structure displayed the greatest modulus and plateau stress. The current approach was effectively employed to modify the static and dynamic mechanical characteristics of lattice unit cells.
The corrugated steel (CS) reinforcement method has been adopted for strengthening dilapidated bridges and culverts owing to its advantages of convenient construction, good corrosion resistance, and high deformability. However, the current design method for corrugated steel retrofitted damaged reinforced concrete (CSRDRC) arches is excessively conservative as it only considers the bearing capacity of the CS, neglecting the contributions of the original reinforced concrete (RC) structure and the infill layer. This paper studied the behaviour of CSRDRC arches under three-point loading experimentally and numerically. The experimental results demonstrate that the bearing capacity and initial stiffness of the arches are significantly enhanced after CS reinforcement. The increase in damage degree of the original structure has a slight effect on the bearing capacity and initial stiffness, but an obvious adverse effect on the ductility of the CSRDRC arches. A finite element model (FEM) was developed and verified against test results and then utilized to conduct parametric analysis. Finally, a simplified formula was proposed for predicting the axial compressive bearing capacity of CSRDRC arches.
Unilateral buckling of thin plates by complementarity eigenvalue analyses
J.M. Figueiredo, F.M.F. Simões, A. Pinto da Costa
doi:10.1016/j.tws.2024.112387
薄板单边屈曲的互补特征值分析
In this work, the analysis by the finite element method of thin plates subjected to buckling in the presence of unilateral punctual obstacles, that is, supports that allow the plate to move in one direction but prevent the motion in the opposite direction, is addressed. An appropriate algorithm based on the solution of a semi-smooth system of equations, that results from the formulation of the unilateral buckling problem as a complementarity eigenvalue problem, is used. Rectangular and square plates are analysed under various membrane loadings, including compression and shear. The conformal Bogner–Fox–Schmit (BFS) finite element is employed to compute the bifurcation loads and the corresponding instability modes in scenarios with and without unilateral obstacles. For each plate and type of loading, the six lowest bifurcation loads and corresponding modes are computed for different levels of mesh refinement. The results confirm that the convergence of bifurcation loads obtained using the BFS element is monotonically decreasing as the mesh is refined. It is also confirmed that, when unilateral obstacles are present, the lowest bifurcation load, known as the critical load, can never be lower than the one of the homologous problem without unilateral obstacles.
Recovery resilience framework of replaceable AB-BRB for seismic strengthening during the aftershock stage
Xu-Yang Cao, Dejian Shen, Kun Ji, Zhe Qu, Chun-Lin Wang
doi:10.1016/j.tws.2024.112389
可替换AB-BRB在余震阶段抗震加固中的恢复弹性框架
Earthquakes cause serious damage to structures, and seismic strengthening is an effective solution to improving structural capacity. With the development of prefabricated technology, the assembled buckling-restrained braces (BRBs) have garnered significant attention in structural engineering due to their potentials to enhance seismic resilience and to guarantee recoverability behavior. At this stage, research on the replaceable performance of assembled BRBs is limited in the current body of literature. The specific focus on the replaceability aspect of assembled BRBs, including the ease of replacing individual components or the entire brace system, has not been extensively explored. Meanwhile, research on earthquake resilience during the aftershock stage is relatively limited at present. Despite the recognition of the significant and prolonged impact of aftershocks on communities and infrastructure, there is a paucity of comprehensive studies specifically focusing on the resilience strategies and measures required during this stage. The authors formerly proposed a novel assembled bolt-connected BRB (AB-BRB), and experiments have been conducted to verify its hysteretic and replaceable behaviors. In this paper, the recovery resilience of the proposed replaceable AB-BRB for seismic strengthening is further assessed, especially during the aftershock stage. The replacement realization of AB-BRB in analysis is first introduced. Then the recovery resilience framework for assessment during the aftershock stage is proposed. Finally an implementary example is given to perform the recovery resilience framework, in which two cases and three scenarios are discussed in detail. In general, after using the AB-BRB for seismic strengthening, the recovery time obviously decreases and the resilience index obviously increases when compared with the results in un-strengthened scenario (scenario 3), which demonstrates that the retrofitted system possesses a better resilience recovery capacity. For EEL in case 1, the recovery days are given to be 298.7446 before strengthening (scenario 3), and the results drop to 165.4133 (scenario 1) and 147.0295 (scenario 2) after strengthening. Correspondingly, the resilience index is calculated as 0.5022 before strengthening (scenario 3), and the results increase to 0.7101 (scenario 1) and 0.7411 (scenario 2) after strengthening. Similar conclusions can be given for case 2 and other intensity levels. Meanwhile, after performing the replacement operation of AB-BRB (scenario 2), the seismic performance of the retrofitted system further enhances during the aftershock stage (i.e., less recovery days and larger resilience index). For case 1 and recovery form 1, the resilience index for 1 month is signified as 0.6272, 0.6869 and 0.2066 from scenario 1 to 3, and the resilience index for 3 months is signified as 0.8182, 0.8561 and 0.4965 from scenario 1 to 3. Compared with scenario 1, the recovery ability in scenario 2 is further ensured and the potential risk is further controlled, which demonstrates the importance of replaceable capacity of AB-BRB for resilience improvement especially during the aftershock stage.
Influence of bionic texture on the mechanical properties of 6061Al/CFRTP laser joints
Jingcheng Li, Yixuan Zhao, Xueyan Zhang, Jianhui Su, Caiwang Tan, Jin Yang, Xiaoguo Song, Wei Song, Guanghui Guo
doi:10.1016/j.tws.2024.112393
仿生织构对6061Al/CFRTP激光接头力学性能的影响
Joining carbon fiber reinforced thermoplastic composites (CFRTP) with metals is a significant challenge for lightweighting in the automotive sector. The lower strength of hybrid joints limits their applications in the relevant fields. In this study, three distinct surface textures were applied to 6061 aluminum alloy (6061Al), including a traditional groove texture and two novel bionic textures (shark skin and fish scale), to enhance the strength of the hybrid joint between the materials. The impact of these textures on the mechanical properties of 6061Al/CFRTP hybrid joints was investigated through experimental methods and finite element simulations. The results indicated that the stress distribution at the interface of the bionic textured samples was more uniform, reducing stress concentration at the interface. Furthermore, the hybrid joint strength was improved as the bionic texture hindered crack initiation and propagation and facilitated crack deflection. Compared to the untextured samples, the fish scale textured samples exhibited the highest strength, which increased by 431.3 % relative to the untextured samples.
