今日更新:International Journal of Solids and Structures 4 篇,Mechanics of Materials 1 篇,International Journal of Plasticity 2 篇
Inverse calibration of out-of-plane shear anisotropy parameters of sheet metal
Bojan Starman, Tomaž Pepelnjak, Andraž Maček, Miroslav Halilovič, Sam Coppieters
doi:10.1016/j.ijsolstr.2025.113313
板料面外剪切各向异性参数的反校正
The accurate description of sheet metal forming processes such as blanking, riveting, incremental forming, and ironing strongly depends on understanding the material’s through-thickness shear resistance and plastic behavior. A three-dimensional model of plastic anisotropy is required to capture this behavior, but calibrating the out-of-plane shear parameters is often challenging. Researchers frequently assume isotropy or set the in-plane and out-of-plane shear parameters equal. More advanced approaches use a crystal plasticity model, which also requires calibration based on available material texture data. In this work, we introduce an out-of-plane shear test procedure that combines a macromechanical test with digital image correlation to inversely calibrate the shear anisotropy parameters of the YLD2004-18p yield function. This method efficiently characterizes both in-plane and out-of-plane shear anisotropy in medium-thick sheet metals.
准确描述钣金成形过程,如落料、铆接、增量成形和熨烫,在很大程度上取决于对材料的全厚度抗剪切性和塑性行为的理解。三维塑性各向异性模型需要捕捉这种行为,但校准面外剪切参数往往具有挑战性。研究人员经常假设各向同性或将面内和面外剪切参数设置为相等。更先进的方法使用晶体塑性模型,该模型也需要基于可用的材料纹理数据进行校准。在这项工作中,我们介绍了一种面外剪切试验程序,该程序将宏观力学试验与数字图像相关相结合,以反向校准YLD2004-18p屈服函数的剪切各向异性参数。该方法有效地表征了中厚金属板的面内和面外剪切各向异性。
Energy-based PINNs using the element integral approach and their enhancement for solid mechanics problems
Junwei Chen, Jianxiang Ma, Zhi Zhao, Xiaoping Zhou
doi:10.1016/j.ijsolstr.2025.113315
基于能量的单元积分pin及其对固体力学问题的改进
Despite the growing interest in physics-informed neural networks (PINNs) for computational mechanics, significant challenges remain in their widespread application. This work proposes an energy-based PINN method rooted in the principle of virtual work, which states that the external work done on a system is equal to its strain energy. This proposed method discretizes the model into nodes and constructs elements based on these nodes. The strain energy of each element is computed through numerical integration, and the total strain energy of the model is obtained by summing these elemental contributions. Simultaneously, the external work is calculated based on the nodal forces. These calculations, combined with the principle of virtual work, allow for the definition of the model’s physical properties. A deep neural network (DNN) is then trained to map the model’s coordinates to their corresponding displacements, utilizing the defined physical properties. Furthermore, this paper proposes a method to accelerate the learning process of energy-based PINNs by using a simpler and converged model to speed up convergence and to improve the overall accuracy of more complex models. Numerical results demonstrate that the proposed approach effectively solves stress concentration and singularity problems in solid mechanics with high accuracy.
尽管人们对物理信息神经网络(pinn)在计算力学中的应用越来越感兴趣,但在其广泛应用中仍存在重大挑战。这项工作提出了一种基于能量的PINN方法,该方法基于虚功原理,即对系统所做的外部功等于其应变能。该方法将模型离散为节点,并基于这些节点构造元素。通过数值积分计算各单元的应变能,将各单元的贡献相加得到模型的总应变能。同时,根据节点力计算外功。这些计算,结合虚功原理,可以定义模型的物理性质。然后训练深度神经网络(DNN)利用定义的物理属性将模型的坐标映射到相应的位移。此外,本文还提出了一种加速基于能量的pinn学习过程的方法,通过使用更简单和收敛的模型来加快收敛速度,并提高更复杂模型的整体精度。数值结果表明,该方法能有效地解决固体力学中的应力集中和奇点问题,精度较高。
Measurement and calculation method for circumferential plastic strain ratio of anisotropic aluminum alloy tubes
Xiao-Lei Cui, Qianxi Sun, Yichun Wang, Shijian Yuan
doi:10.1016/j.ijsolstr.2025.113311
各向异性铝合金管周向塑性应变比的测量与计算方法
To improve the finite element analysis (FEA) accuracy of forming hollow tubular components, it is urgent to determine the circumferential mechanical properties of thin-walled tube blanks, especially the plastic strain ratio rθ, and further investigate their anisotropic deformation and hardening behaviors. In this paper, a new segment-type ring expansion test (SRET) method was established for directly measuring rθ based on digital image correlation (DIC). It was shown by theoretical analysis that an approximately uniaxial and uniform stress state can be generated when the number of segments is 12 and the initial width-to-diameter ratio of the specimen is about 0.10. It was experimentally proved that the relative error of the measured rθ of 304 stainless steel welded tube was less than 1 % compared with the r-value of the original 304 sheet. Then, the rθ of aluminum alloy (6061) tubes was obtained by the SRET method, and the biaxial tensile deformation of the tubes was realized by a controllable biaxial tension test. It is shown that the axial and circumferential plastic strain ratios were 0.460 and 0.638, respectively. The strain path of equal-biaxial stress deviated from the equal-biaxial strain path, and the strain paths of σz/σθ= 0.75 and 1.333 (reciprocal) were asymmetrically distributed along the equal-biaxial strain line. These results indicate the tubes’ apparent anisotropic deformation behaviors. Finally, the effect of rθ and yield criterion on predicting the anisotropic hardening behavior was analyzed using the effective stress–strain curve. The results illustrate that rθ must be considered, and the Balart89 yield criterion with higher order has higher accuracy compared with the Hill48 yield criterion. This research is significant for improving and evaluating the prediction accuracy of plastic constitutive models.
为了提高空心管状件成形的有限元分析(FEA)精度,迫切需要确定薄壁管坯的周向力学性能,尤其是塑性应变比 rθ,并进一步研究其各向异性变形和硬化行为。本文基于数字图像相关(DIC)技术,建立了一种新的分段式环向扩张试验(SRET)方法,用于直接测量 rθ。理论分析表明,当分段数为 12 且试样初始宽度与直径之比约为 0.10 时,可产生近似单轴且均匀的应力状态。实验表明,304 不锈钢焊接管的 rθ 测量值与原始 304 板材的 r 值相比,相对误差小于 1%。然后,通过 SRET 方法获得了铝合金(6061)管的 rθ,并通过可控双轴拉伸试验实现了管材的双轴拉伸变形。结果表明,轴向和周向塑性应变比分别为 0.460 和 0.638。等双轴应力的应变路径偏离了等双轴应变路径,而 σz/σθ = 0.75 和 1.333(倒数)的应变路径沿等双轴应变线呈不对称分布。这些结果表明管材表现出明显的各向异性变形行为。最后,利用有效应力 - 应变曲线分析了 rθ 和屈服准则对预测各向异性硬化行为的影响。结果表明必须考虑 rθ,且与 Hill48 屈服准则相比,更高阶的 Balart89 屈服准则具有更高的精度。这项研究对于提高和评估塑性本构模型的预测精度具有重要意义。
Constitutive modelling and validating of annealed copper under various stress states, strain rates and temperatures
Yutian Du, Zejian Xu, Hongzhi Hu, Mengyu Su, Ang Hu, Fenglei Huang
doi:10.1016/j.ijsolstr.2025.113312
退火铜在不同应力状态、应变速率和温度下的本构建模和验证
Metallic materials and structures are often subjected to a wide range of strain, strain rate, temperature and stress state during the engineering application. In order to study the plastic and deformation characteristics of metallic materials under complex stress states, it is necessary to use a constitutive model that considers the effects of stress states. Based on shear specimens suitable for hydraulic Instron testing machines and Hopkinson bar systems (SHPB and SHTB), the compression-shear and tension-shear specimens are designed to achieve complex stress states. Through a combination of test and parallel finite element simulation, stress–strain curves of the material under various stress states were obtained. Additionally, mechanical property tests were conducted on specimens under typical stress states (uniaxial compression, uniaxial tension, and shear) at a wide range of strain rates and temperatures. To describe the plastic mechanical behavior of materials, a new plastic constitutive model considering temperature, strain rate, and stress state is proposed. Then the model was embedded into the ABAQUS/Explicit finite element software through the VUMAT user material subroutine for numerical simulation. The performance of the new model was systematically compared and analyzed with that of Johnson-Cook model and Xu et al.’s model. The ability of the prediction of plastic deformation in Taylor impact test was evaluated for different models. The results show that the new constitutive model is suitable for predicting the impact deformation associated with complex strain rates, temperatures, and stress states.
在工程应用过程中,金属材料和结构往往要承受大范围的应变、应变速率、温度和应力状态。为了研究复杂应力状态下金属材料的塑性和变形特性,有必要采用考虑应力状态影响的本构模型。以适用于液压压力试验机和霍普金森杆系统(SHPB和SHTB)的剪切试件为基础,设计了压剪和拉剪试件,以实现复杂的应力状态。通过试验与平行有限元模拟相结合,得到了材料在不同应力状态下的应力应变曲线。此外,在较宽的应变速率和温度范围内,对试件进行了典型应力状态(单轴压缩、单轴拉伸和剪切)下的力学性能测试。为了描述材料的塑性力学行为,提出了一种考虑温度、应变速率和应力状态的塑性本构模型。然后通过VUMAT用户材料子程序将模型嵌入到ABAQUS/Explicit有限元软件中进行数值模拟。将新模型的性能与Johnson-Cook模型和Xu等人的模型进行了系统的比较和分析。对不同模型在Taylor冲击试验中预测塑性变形的能力进行了评价。结果表明,该本构模型适用于复杂应变率、温度和应力状态下的冲击变形预测。
A poroelastic model of the optic nerve shows a significant effect of fluid pressure on the nerve fibers.
Denis Kucherenko, Arina Korneva
doi:10.1016/j.mechmat.2025.105299
视神经的孔弹性模型显示了流体压力对神经纤维的显著影响。
The structure of the optic nerve resembles a cylindrical composite where the pia mater surrounds the nervous tissue which is saturated with interstitial fluid. This interstitial fluid is necessary for effective nerve conduction of visual signals. The reaction of the optic nerve to physiological loads remains unknown. Current computational and material models do not fully capture the complexities of this tissue’s structure, particularly the biofluid has not yet been considered as a load-supporting material. We developed a microstructurally motivated analytical model of a cylindrical composite with a poroelastic core and an elastic outer layer subjected to an axial load. We examined the effect of the geometry and the material parameters of the composite on the stress distribution across the composite. We found physiologically relevant conditions when the outer layer and the biofluid support most of the applied stress relative to the solid constituents of the core. The model shows that the fluid pressure can be as large as one third of the applied stress. The model makes possible the fluid pressure injuring nerve fibers. This scenario is missing in studies modeling the optic nerve as an elastic solid. We examined how variations in outer layer thickness and compressibility of animal nerves or materials stiffen the stress-strain response. This study provides guidelines for measuring and comparing the material parameters between diseased, aged, and healthy nerves and similar biomaterials. The model can be used to analyze mechanics of similar composites.
视神经的结构类似于一个圆柱形的复合物,其中软脑膜包围着充满间质液的神经组织。这种间质液对于视觉信号的有效神经传导是必要的。视神经对生理负荷的反应尚不清楚。目前的计算和材料模型并没有完全捕捉到这种组织结构的复杂性,特别是生物流体尚未被认为是一种负载支撑材料。我们开发了一个微观结构驱动的圆柱形复合材料的分析模型,具有孔弹性核心和弹性外层受到轴向载荷。我们研究了复合材料的几何形状和材料参数对复合材料应力分布的影响。我们发现了与生理相关的条件,当外层和生物流体相对于核心的固体成分支持大部分施加的应力时。该模型表明,流体压力可达施加应力的三分之一。该模型使液体压力损伤神经纤维成为可能。在将视神经建模为弹性固体的研究中,这种情况是缺失的。我们研究了动物神经或材料的外层厚度和可压缩性的变化如何使应力-应变反应变硬。本研究为测量和比较患病、衰老和健康神经与类似生物材料之间的材料参数提供了指导。该模型可用于类似复合材料的力学分析。
Manipulating the interfacial structures in titanium alloys containing interstitial solutes delivers ultra-high strength and ductility
Hang Zhang, Xuanzhe Li, Jinyu Zhang, Suzhi Li, Shaohua Gao, Gang Liu, Jun Sun
doi:10.1016/j.ijplas.2025.104288
控制含间隙溶质的钛合金的界面结构可提供超高的强度和延展性
Design structural characteristics of interfaces is the key for ultra-strong titanium (Ti) alloys by tuning polymorphic α-precipitates. However, the conventional tri-modal structure, characterized by various interfaces, usually shows large ductility but low yield strength caused by numerous soft α-precipitates. This work focuses on manipulating multiple interfacial structures to endow a newly designed tri-modal Ti-4.9Al-4.4Cr-2.45Mo-1.6Zr alloys with the superior strength-ductility synergy assisted by interstitial solutes, beyond conventional high-strength Ti alloys. Here, an interstitial solute alloying strategy is utilized not only to form hard-yet-deformable α-precipitates, but also to achieve the controllably stepwise α-precipitation sequence to manipulate interfacial structures and thus slip transmission modes in Ti alloys. In particular, the coherent twin boundaries (CTBs) between secondary α-nanolamellae formed via dislocation-interstitial atom interactions can efficiently hinder dislocation motion but promote dislocation transmission in the soft transformed β-matrix. This strategy provides new insights into designing high-performance interstitial solute-tolerant alloys for cost-effective and lightweight applications.
设计界面结构特征是调整多晶α-析出物的关键。而传统的三模态结构,由于界面多样,由于α-软相较多,塑性大,屈服强度低。本工作的重点是操纵多个界面结构,赋予新设计的三模态Ti-4.9 al -4.4 cr -2.45 mo -1.6 zr合金在间隙溶质的辅助下具有优于传统高强度钛合金的强度-塑性协同作用。本文采用间隙溶质合金化策略,不仅可以形成坚硬且可变形的α-析出相,还可以实现可控制的逐步α-析出序列,从而控制界面结构,从而改变Ti合金中的滑移传递模式。特别是,位错-间隙原子相互作用形成的次生α-纳米片间的相干孪晶界(CTBs)可以有效地阻碍位错运动,但促进位错在软相变β-基体中的传递。这一策略为设计具有成本效益和轻量化应用的高性能间质耐溶质合金提供了新的见解。
Effect of precipitate phase on the plastic deformation behavior of Alloy 718: in-situ tensile experiment and crystal plasticity simulation
Guanghao Guo, Wenqiang Zhang, Bin Zhang, Jiachen Xu, Shuang Chen, Xianjue Ye, Yuefei Zhang, Ze Zhang
doi:10.1016/j.ijplas.2025.104286
析出相对718合金塑性变形行为的影响:原位拉伸实验与晶体塑性模拟
In this study, in-situ tensile experiments were conducted on three samples containing different precipitate phases (δ, γ″ and γ′) to investigate the effects of these precipitates on the tensile deformation mechanisms of Alloy 718. Local plastic deformation was characterized by digital image correlation (DIC) and electron back-scatter diffraction (EBSD). The plasticity was analyzed in terms of slip, lattice rotation, slip transfer, and intergranular cooperative deformation. The dislocation accumulation is slower in the γ matrix, promoting uniform plastic deformation within grains via single slip, resulting in excellent intragranular deformation capability for the sample without any precipitates. In contrast, the γ″ and γ′ phases facilitate dislocation multiplication and impede dislocation motion, causing rapid dislocation pile-up within grains, leading to local stress concentrations. These stress concentrations can activate secondary slip systems early, resulting in uneven intragranular deformation and limiting the grains’ plastic deformation capacity for the sample with γ′′ and γ′. At grain boundaries, the δ phase hinders slip transfer, restricting the capacity for intergranular coordinated deformation, resulting in the formation of microcracks along the grain boundaries. These microcracks, along both the δ phase and the grain boundaries, contribute to the reduction in plasticity of the sample with δ phase. The effects of γ″ and γ′ phases are similar, as they limit grain deformation by influencing dislocation accumulation within grains, while the δ phase at grain boundaries reduces the tensile plasticity of Alloy 718 by impeding intergranular deformation coordination.
通过原位拉伸实验,研究了不同析出相(δ、γ″和γ′)对718合金拉伸变形机制的影响。采用数字图像相关(DIC)和电子背散射衍射(EBSD)对局部塑性变形进行了表征。从滑移、晶格旋转、滑移传递和晶间协同变形等方面分析了材料的塑性。位错在γ基体中的积累速度较慢,通过单次滑移促进晶粒内均匀的塑性变形,从而使样品具有良好的晶内变形能力,且无析出物。相反,γ″和γ′相促进位错增殖,阻碍位错运动,导致位错在晶粒内快速堆积,导致局部应力集中。这些应力集中可以早期激活二次滑移系统,导致晶内变形不均匀,限制了γ′和γ′试样的塑性变形能力。在晶界处,δ相阻碍了滑移转移,限制了晶间协调变形的能力,导致沿晶界形成微裂纹。沿δ相和晶界的微裂纹导致δ相试样的塑性降低。γ″和γ′相的作用相似,它们通过影响位错在晶内的积累来限制晶粒变形,而晶界处的δ相通过阻碍晶间变形配位来降低合金718的拉伸塑性。