今日更新：Journal of the Mechanics and Physics of Solids 1 篇，Mechanics of Materials 1 篇，International Journal of Plasticity 1 篇，Thin-Walled Structures 6 篇Journal of the Mechanics and Physics of SolidsNumerical and Experimental Crack-tip Cohesive Zone Laws with Physics-Informed Neural NetworksH. Tran, Y.F. Gao, H.B. Chewdoi:10.1016/j.jmps.2024.105866基于物理信息神经网络的裂纹尖端内聚区规律的数值和实验研究The cohesive zone law represents the constitutive traction versus separation response along the crack-tip process zone of a material, which bridges the microscopic fracture process to the macroscopic failure behavior. Elucidating the exact functional form of the cohesive zone law is a challenging inverse problem since it can only be inferred indirectly from the far-field in experiments. Here, we construct the full functional form of the cohesive traction and separation relationship along the fracture process zone from far-field stresses and displacements using a physics-informed neural network (PINN), which is constrained to satisfy the Maxwell-Betti's reciprocal theorem with a reciprocity gap to account for the plastically deforming background material. Our numerical studies simulating crack growth under small-scale yielding, mode I loading, show that the PINN is robust in inversely extracting the cohesive traction and separation distributions across a wide range of simulated cohesive zone shapes, even for those with sharp transitions in the traction-separation relationships. Using the far-field elastic strain and residual elastic strain measurements associated with a fatigue crack for a ZK60 magnesium alloy specimen from synchrotron X-ray diffraction experiments, we reconstruct the cohesive traction-separation relationship and observe distinct regimes which suggest corresponding transitions in the micromechanical damage mechanisms.黏聚区规律代表了材料沿裂纹尖端过程区的本构牵引与分离响应，它将微观断裂过程与宏观破坏行为联系起来。由于在实验中只能间接地从远场推断出内聚带定律的确切函数形式，因此阐明内聚带定律的确切函数形式是一个具有挑战性的逆问题。在这里，我们利用物理信息神经网络(PINN)构建了沿断裂过程带的远场应力和位移的内聚牵引和分离关系的完整函数形式，该网络被约束于满足麦克斯韦-贝蒂的互易定理，并具有互易间隙以解释塑性变形的背景材料。我们的数值研究模拟了小尺度屈服I型加载下的裂纹扩展，结果表明，即使对于那些牵引-分离关系发生急剧转变的区域，PINN在反提取大范围模拟黏结区形状的黏结牵引和分离分布方面也是鲁棒的。利用同步x射线衍射实验得到的ZK60镁合金试样的远场弹性应变和残余弹性应变，重构了疲劳裂纹的内聚牵引-分离关系，并观察到微观力学损伤机制的不同转变。Mechanics of MaterialsFailure analysis of unidirectional fiber reinforced plastics based on computational micromechanics and PUCK failure theoryXiaofei Pang, Yonglyu He, Xun Chen, Shufeng Zhangdoi:10.1016/j.mechmat.2024.105169基于计算细观力学和PUCK破坏理论的单向纤维增强塑料失效分析Achievement of accurate and reliable failure criterion is fundamentally important for designing composite structures. This study comprehensively evaluated the failure of unidirectional fiber-reinforced plastics (FRP) from the perspectives of failure theory and computational micromechanics. Further, PUCK failure criterion was analyzed in detail to identify the specific effects of the interfacial reinforcement coefficient on the failure mechanism. The representative volume element model of FRP with randomly distributed fibers was established. The comparative analysis of the results between current failure theory and experiment, indicates that the load bearing capacity of FRP under bi-axial compressive stress and shear stress is understated by the PUCK failure criterion. Microscopic finite element analysis was adopted to investigate the failure envelope of FRP, considering interface reinforcement coefficient. The results reveal that the strength of FRP under the combination of moderate transverse compressive stress and in-plane shear stress is significantly affected by the interface reinforcement coefficient. The accuracy of PUCK failure criterion heavily depends on the value of the interface reinforcement coefficient and if the criterion does not consider the coefficient, it can cause notable error on strength prediction. Consequently, determination of interface reinforcement coefficient would be helpful to achieve more accurate failure criterion for FRP.获得准确可靠的失效准则对复合材料结构的设计至关重要。本文从破坏理论和计算细观力学的角度对单向纤维增强塑料(FRP)的破坏进行了综合评价。进一步对PUCK破坏准则进行了详细分析，明确了界面配筋系数对破坏机制的具体影响。建立了具有代表性的纤维随机分布FRP的体积元模型。对现有破坏理论与试验结果的对比分析表明，PUCK破坏准则低估了FRP在双轴压应力和剪切应力作用下的承载能力。考虑界面配筋系数，采用细观有限元方法研究FRP的破坏包络线。结果表明:在中等横向压应力和面内剪应力作用下，界面配筋系数对FRP强度有显著影响;PUCK破坏判据的精度很大程度上取决于界面配筋系数的取值，如果不考虑界面配筋系数，则会对强度预测产生较大的误差。因此，界面配筋系数的确定有助于获得更准确的FRP破坏判据。International Journal of PlasticityA 3D finite deformation constitutive model for anisotropic shape memory polymer composites integrating viscoelasticity and phase transition conceptChengjun Zeng, Yunqiang Hu, Liwu Liu, Xiaozhou Xin, Wei Zhao, Yanju Liu, Jinsong Lengdoi:10.1016/j.ijplas.2024.104139结合粘弹性和相变概念的各向异性形状记忆聚合物复合材料三维有限变形本构模型The phase transition theory of shape memory polymers (SMPs) often involves a phenomenological assumption that the reference configuration of the newly transformed phase deviates from that of the initial phase. This distinction serves as a crucial mechanism in the manifestation of the shape memory effect. However, elucidating the precise definition of the reference configuration of the transformed phase poses a significant challenge in the formulation of the constitutive model. To tackle this challenge, a three-dimensional (3D) finite deformation constitutive model incorporating effective phase evolution for SMPs has been developed. This model merges insights from the classical viscoelastic framework with the phase transition theory. The anisotropic thermo-viscoelastic constitutive model is further developed by introducing hyperelastic fibers, which integrate the anisotropy of the fibers into a continuous thermodynamic framework through structure tensors. Implemented within the ABAQUS software via a user material (UMAT) subroutine, the proposed model has been meticulously validated against experimental data, showcasing its prowess in simulating stress-strain responses and shape memory characteristics of SMPs and their composites (SMPCs). This innovative model stands as an invaluable instrument for the design and of sophisticated SMP and SMPC structures.形状记忆聚合物(SMPs)的相变理论通常涉及一个现象学假设，即新转变相的参考构型偏离初始相。这种区别是形状记忆效应表现的关键机制。然而，在本构模型的制定中，阐明转换相的参考构型的精确定义是一个重大的挑战。为了应对这一挑战，研究人员开发了包含有效相演化的smp三维有限变形本构模型。该模型融合了经典粘弹性框架与相变理论的见解。引入超弹性纤维，将纤维的各向异性通过结构张量整合到一个连续的热力学框架中，进一步发展了各向异性热粘弹性本构模型。该模型通过用户材料(UMAT)子程序在ABAQUS软件中实现，并通过实验数据进行了仔细验证，展示了其在模拟应力应变响应和smpc及其复合材料(smpc)形状记忆特性方面的能力。这种创新的模型是设计和复杂的SMP和SMPC结构的宝贵工具。Thin-Walled StructuresDynamic Analysis of Carbon Fiber-Wound Reinforced Composite Truncated Conical Shell Under Thermal Conditions: Theory and Experimental ValidationShufeng Lu, Richa Hu, Hailong Qiao, Yang Yang, Wei Zhang, Xiaojuan Songdoi:10.1016/j.tws.2024.112496热条件下碳纤维缠绕增强复合材料截锥形壳的动力学分析:理论与实验验证This work aims to investigate the dynamic behavior of a carbon fiber-wound reinforced composite (FW-RC) truncated conical shell structure under various operating conditions, including transverse excitation and winding pre-stress in thermal environment. In particular, a dynamic model for the FW-RC truncated conical shell is established, taking into account the first-order shear deformation theory and the von Karman geometric relationship. By utilizing Hamilton's principle and Galerkin method, the dynamic equations for the FW-RC truncated conical shells are derived. The natural frequencies of the system are afterward determined, and a vibration test bench is constructed specifically for the truncated conical shells. The validity of the theoretical model is verified by measuring the natural frequency of the specimen. In addition, the effects of various factors such as temperature field, pre-stress, boundary conditions, geometric parameters, and fiber winding parameters on the inherent characteristics and dynamic behavior of the system are further studied. By delving into these aspects, a comprehensive understanding of the dynamic behavior of FW-RC truncated conical shell structures can be achieved, which is of great significance for their design and application in practical engineering scenarios.本文旨在研究碳纤维缠绕增强复合材料(FW-RC)截顶锥形壳结构在不同工况下的动力行为，包括横向激励和缠绕预应力。考虑一阶剪切变形理论和von Karman几何关系，建立了FW-RC截锥壳的动力模型。利用Hamilton原理和Galerkin方法，推导了FW-RC截顶圆锥壳的动力学方程。随后确定了系统的固有频率，并搭建了专门针对截锥壳的振动试验台。通过对试件固有频率的测量，验证了理论模型的有效性。此外，还进一步研究了温度场、预应力、边界条件、几何参数、纤维缠绕参数等因素对系统固有特性和动态行为的影响。通过对这些方面的深入研究，可以全面了解FW-RC截锥壳结构的动力特性，对其设计和实际工程应用具有重要意义。Design of lattice metamaterials under the equal strength concept and research on the mechanical properties of their sandwich structuresChenglin Tao, Zhao Wang, Rui Zhao, Zeliang Liudoi:10.1016/j.tws.2024.112498 等强度概念下晶格超材料的设计及其夹层结构的力学性能研究This study proposes a novel lattice metamaterial with equal strength struts based on the concept of equal strength of beams, which has been designated the strut-enhanced body-centered cubic lattice structure (EBCC). The structure is capable of effectively reducing the stress concentration of the lattice structure at the nodes and increasing the structural energy absorption. The effective elastic properties of EBCC unit cells are investigated in detail under periodic boundary conditions (PBC), and the results show that the deformation response of the unit cell under compressive loading is dominated by bending. A novel sandwich structure, designated S-EBCC, was developed utilizing EBCC as the core material. The effects of geometrical parameters and relative density on the deformation mechanism and mechanical properties of the sandwich structure were analyzed through experiments, numerical simulations and theoretical predictions. The results show that under compressive loading, the stress concentration at the nodes of the EBCC structure is effectively improved and the peak stress is reduced while the energy absorption is increased compared with the traditional S-BCC structure. Under three-point bending load, the larger the strut angle of the S-EBCC structure, the higher the load capacity. Comparison of experimental and theoretical results shows that the failure modes of the S-EBCC structure under both compressive and three-point bending loads are plastic yield.基于梁的等强度概念，提出了一种具有等强度杆的新型晶格超材料，并将其命名为杆增强体心立方晶格结构(EBCC)。该结构能够有效降低节点点阵结构的应力集中，增加结构的能量吸收。详细研究了周期边界条件下EBCC单元格的有效弹性特性，结果表明，在压缩载荷作用下，单元格的变形响应以弯曲为主。以EBCC为核心材料，开发了一种新型的夹层结构，称为S-EBCC。通过实验、数值模拟和理论预测，分析了几何参数和相对密度对夹层结构变形机理和力学性能的影响。结果表明:与传统的S-BCC结构相比，在压缩荷载作用下，EBCC结构节点应力集中得到有效改善，峰值应力降低，能量吸收增加;在三点弯曲荷载作用下，S-EBCC结构的杆角越大，承载能力越高。实验结果与理论结果的比较表明，S-EBCC结构在压缩和三点弯曲荷载作用下的破坏模式均为塑性屈服。Energy dissipation and power flow analysis based on acoustic black hole laminated beamsWeijie Yu, Yuhao Zhao, Mingfei Chen, Guoyong Jindoi:10.1016/j.tws.2024.112503基于声黑洞层合梁的能量耗散与潮流分析To enhance the understanding of the dynamic performance of composite beams, assessing their energy accumulation and dissipation capabilities is crucial. The purpose of this paper is to establish a dynamic analysis model of acoustic black hole (ABH) laminated beams based on the Timoshenko beam theory and isogeometric method and to analyze structural intensity and power flow. The vibration governing equation for the ABH laminated beam is derived by calculating its potential and kinetic energy. The convergence of the results is confirmed through multiple mesh refinements, while the model's accuracy and applicability are substantiated through comparisons with the literature, traditional finite element simulations, and experimental data. This investigation into the power flow and structural intensity under varying parameter conditions elucidates the energy transfer mechanisms within ABH laminated beams, offering valuable insights for the deployment of ABH technologies in practical engineering applications.为了提高对组合梁动力性能的认识，对其能量积累和耗散能力进行评估是至关重要的。本文的目的是基于Timoshenko光束理论和等几何方法建立声黑洞(ABH)层合梁的动力学分析模型，并对其结构强度和功率流进行分析。通过计算ABH层合梁的势能和动能，推导出ABH层合梁的振动控制方程。通过多次网格细化验证了结果的收敛性，并通过与文献、传统有限元仿真和实验数据的对比验证了模型的准确性和适用性。本研究对不同参数条件下的功率流和结构强度进行了研究，阐明了ABH层合梁内部的能量传递机制，为ABH技术在实际工程应用中的部署提供了有价值的见解。In-plane crashworthiness study of bio-inspired metallic lattice structure based on deep-sea glass spongeHongbo Zhang, Dayong Hu, Haojie Peng, Wentao Yuan, Zhen Zhang, Zhenyu Yang, Zhixian Zhangdoi:10.1016/j.tws.2024.112505 深海玻璃海绵仿生金属晶格结构的机内耐撞性研究Inspired by the double-diagonal reinforced configuration of deep-sea glass sponges, a metallic bio-inspired lattice structure (BLS) was fabricated using additive manufacturing (AM) techniques. In-plane quasi-static compression tests demonstrated the energy absorption (EA) of BLS was improved by about 60% compared to conventional lattice designs. Subsequent experimental and numerical investigations examined the effects of wall thickness, elucidating the corresponding variations in crashworthiness indicators. The study revealed that when the wall thickness increased from 0.40 mm to 0.60 mm, the EA and mean crushing force (Pm) exhibited a substantial increment of 58.1% and 91.1%, respectively. The finite element (FE) simulations underwent experimental validation, exhibiting satisfactory agreement. Parametric studies using the validated FE model explored the effects of geometric factors, such as diagonal distance, unit size, unit number and graded thickness on the crushing performance of BLS. Results indicated that enhancing the EA performance of BLS was achievable by concurrently reducing the unit size and increasing the unit number. The maximum EA achieved was 3535.5 J, representing a 62.9% improvement compared to the initial configuration, which exhibited an EA of 2170.7 J. Additionally, the introduction of graded thickness facilitated a controllable collapse pattern, thereby improving the crashworthiness performance. Lastly, the in-plane dynamic crushing simulations were conducted, identifying three distinct collapse patterns, where the U-Mode exhibiting a negative Poisson's ratio (NPR) behavior. A deformation mode map and rigid-perfectly plastic-lock (R-PP-L) model were developed to evaluate the dynamic response of BLS under varying relative density (RD) and impact velocity (V). These findings provided valuable insights for designing sponge-inspired structures with enhanced crashworthiness performance.受深海玻璃海绵双对角线增强结构的启发，采用增材制造(AM)技术制造了金属仿生晶格结构(BLS)。平面内准静态压缩试验表明，与传统的点阵设计相比，BLS的能量吸收提高了约60%。随后的实验和数值研究检查了壁厚的影响，阐明了相应的耐撞性指标的变化。研究表明，当壁厚从0.40 mm增加到0.60 mm时，EA和平均破碎力(Pm)分别大幅增长58.1%和91.1%。有限元模拟结果与实验结果吻合较好。利用验证的有限元模型进行参数化研究，探讨了对角线距离、单元尺寸、单元数量和分级厚度等几何因素对BLS破碎性能的影响。结果表明，通过同时减小单元尺寸和增加单元数量，可以提高BLS的EA性能。最大EA为3535.5 J，与初始配置的2170.7 J相比，提高了62.9%。此外，渐变厚度的引入促进了可控的坍塌模式，从而提高了耐撞性能。最后，进行了面内动态破碎模拟，确定了三种不同的破坏模式，其中u型表现为负泊松比(NPR)行为。研究人员建立了变形模式图和刚性-完美塑性锁(R-PP-L)模型，以评估BLS在不同相对密度(RD)和冲击速度(V)下的动态响应。这些发现为设计具有增强耐撞性能的海绵结构提供了有价值的见解。Energy absorption structure with negative stepped plateau force characteristics under quasi-static loadsXin Wang, Liuxiao Zou, Chaocan Cai, Ruojun Wang, Xin Huang, Huiran Zou, Minglong Yang, Zengyan Jiang, Weilong Yindoi:10.1016/j.tws.2024.112506准静态载荷下具有负阶梯平台力特性的吸能结构The force-displacement curve is the key to determine the energy absorption performance. Customizing the force-displacement curve enables the design of more advanced and efficient energy absorption systems. In this paper, we introduce a negative stepped plateau force structure (NSPFS) design by combining crooked plate units with curved and straight combined cross-section (CSCC) units. First, the NSPFS is fabricated by using additive manufacturing technology, and a compression experiment is conducted to validate the design methodology. Then, a finite element model is developed and compared with the experimental results to verify its effectiveness. The peak force (PF) and mean crushing force (MCF) of the crooked plate unit are primarily controlled by wall thickness t1 and initial angle θ1. When θ1=1.146° and t1=1.0mm of crooked plate unit, the lowest point of the plateau phase decreases by 84% compared to the PF, and the ratio of PF to MCF is 4.9. When the PF of the crooked plate unit is greater than the PF of the CSCC unit, the structure has the characteristics of negative stepped plateau force. More phase plateau forces can be obtained when multiple NSPFS are compressed in series. When multiple NSPFS units are compressed in parallel, multi-phase continuous negative stepped plateau force can be achieved. Therefore, NSPFS allows for the customization of complex force-displacement curves through series and parallel design.力-位移曲线是确定吸能性能的关键。定制力-位移曲线可以设计出更先进、更高效的能量吸收系统。本文介绍了弯曲板单元与弯曲直截面组合单元相结合的负阶梯式平台受力结构设计。首先，采用增材制造技术制备了NSPFS，并进行了压缩实验来验证设计方法。建立了有限元模型，并与实验结果进行了对比，验证了该方法的有效性。弯板机组的峰值力(PF)和平均破碎力(MCF)主要受壁厚t1的控制初始角θ1。当θ1=1.146°和t1=1.0mm弯板单元时，平台相最低点较PF降低84%，PF与MCF之比为4.9。当弯板单元的PF大于CSCC单元的PF时，结构具有负阶梯平台力的特征。对多个NSPFS进行串联压缩可以得到更多的相平台力。当多个NSPFS单元并联压缩时，可以实现多相连续负阶梯平台力。因此，NSPFS允许通过串联和并联设计定制复杂的力-位移曲线。Characterization of the stress-state dependent ductile fracture behavior for Q960 ultra-high-strength structural steelMingxu Shang, Hua Yang, Sebastian Münstermanndoi:10.1016/j.tws.2024.112508Q960超高强度结构钢应力状态相关韧性断裂行为表征Ultra-high-strength structural steels are gaining popularity in civil engineering due to their exceptional strength-to-weight ratio. However, their inherent lower ductility compared to normal strength structural steel warrants particular attention and further investigation for safety assessment. In this study, a total of 24 specimens made of Q960 ultra-high-strength steel (UHSS), including 21 tensile specimens with various stress states and 3 three-point bending specimens, were tested to assess its mechanical behavior undergoing large deformation. Subsequently, the impact of stress state on plasticity, damage evolution and fracture initiation was analyzed and characterized. The Bai-Wierzbicki yield surface with a deviatoric associated flow rule was identified to characterize the complex plasticity behavior of Q960 UHSS. With respect to damage evolution, the stress-state dependent fracture energy Gf was proposed in this study to describe the damage softening behavior. The uncoupled Hosford-Coulomb locus with a non-linear weight function was utilized to predict the fracture initiation behavior. Finally, the utilized stress-state dependent constitutive models for Q960 UHSS, with the calibrated parameters and user-defined material subroutine VUMAT, were successfully verified through the three-point bending test with good agreement. Moreover, based on a parametric analysis of radius-to-thickness ratio, the bendability design regarding the minimum radius-to-thickness ratio of Q960 UHSS was proposed.由于其卓越的强重比，超高强度结构钢在土木工程领域日益受到青睐。然而，与普通强度结构钢相比，其固有的塑性较低，这一特性在安全评估中值得特别关注和深入研究。在本研究中，总共对 24 个由 Q960 超高强度钢（UHSS）制成的试样进行了测试，其中包括 21 个处于不同应力状态的拉伸试样和 3 个三点弯曲试样，以评估其在大变形情况下的力学行为。随后，分析并表征了应力状态对塑性、损伤演化和断裂起始的影响。采用具有偏应力相关流动法则的 Bai-Wierzbicki 屈服面来刻画 Q960 UHSS 的复杂塑性行为。对于损伤演化，本研究提出了与应力状态相关的断裂能 Gf ，以描述损伤软化行为。利用具有非线性权重函数的非耦合 Hosford-Coulomb 轨迹来预测断裂起始行为。最后，通过三点弯曲试验成功验证了所采用的 Q960 UHSS 应力状态相关的本构模型，校准后的参数和用户自定义材料子程序 VUMAT 与试验结果吻合良好。此外，基于对半径厚度比的参数分析，提出了 Q960 UHSS 关于最小半径厚度比的弯曲性设计方案。来源：复合材料力学仿真Composites FEM
