【新文速递】2023年12月26日固体力学SCI期刊最新文章

今日更新：International Journal of Solids and Structures 2 篇，Journal of the Mechanics and Physics of Solids 1 篇，Mechanics of Materials 1 篇，Thin-Walled Structures 2 篇

International Journal of Solids and Structures

Research on dynamic deformation behaviors of laser-driving metal sheet precision forming

Xingquan Zhang, Hangxuan Liu, Yinkai Wang, Shiwei Duan, Yan Zhang, Jinxiu Fang, Shanbao Pei, Wenfeng Hu

doi:10.1016/j.ijsolstr.2023.112631

激光驱动金属板精密成形的动态变形行为研究

Laser shock forming (LSF) is an advanced sheet forming technology. With the aid of forming die, it can realize sheet precise forming, and has extensive application prospects in aeronautic and electronics industries. In the paper, a two-dimensional axial symmetric numerical model of SUS304 stainless steel is established. Finite element method is utilized to explore the dynamic deformation behaviors of the laser-driving sheet impacted by the forming die. The results show that the node velocity of metal sheet increases in an oscillatory manner during initial stage and then it starts to bulge. After collision with die cavity bottom, the central region of metal sheet jumps up reversely, and experiences repeating damped vibration. The metal sheet gradually exhausts the obtained kinetic energy from the shock wave, and the flat sheet is finally shaped into the geometrical shape of die cavity. The sheet forming precision can be improved by way of increasing laser shock pressure. The corresponding experiments are also carried out to verify the predicted results. The applied method and gained results can provide a reference for theoretical research and parameters optimization in LSF.

激光冲击成形（LSF）是一种先进的板材成形技术。借助成形模具，它可以实现板材的精密成形，在航空和电子行业具有广泛的应用前景。本文建立了 SUS304 不锈钢的二维轴对称数值模型。利用有限元方法探讨了激光驱动板材在成形模冲击下的动态变形行为。结果表明，金属片的节点速度在初始阶段以振荡方式增加，然后开始隆起。与模腔底部碰撞后，金属片的中心区域反向跃起，并经历重复的阻尼振动。金属片逐渐耗尽从冲击波中获得的动能，最终形成符合模腔几何形状的扁平金属片。通过增加激光冲击压力可以提高金属板的成型精度。为验证预测结果，还进行了相应的实验。所应用的方法和获得的结果可为 LSF 的理论研究和参数优化提供参考。

Energy processes and phase transition in granular assemblies

Xiaoxiao Wang, Yang Liu, François Nicot

doi:10.1016/j.ijsolstr.2023.112634

颗粒集 合体中的能量过程和相变

Granular assemblies are an illustrative example of complex material where unexpected macroscopic properties may emerge when they are subjected to a given loading. The complexity is the consequence of the huge geometrical disorder governed by particle rearrangements, entailing plastic dissipation at contacts. This local dissipation, associated with the global geometric disorder, is probably a key ingredient responsible for various macroscopic features, such as the strain localization in dense granular assemblies leading to the formation of a shear band. Based on a discrete element method (DEM), this manuscript investigates the energy processes at the microscopic scale in granular assemblies along biaxial loading paths for dense and loose assemblies. The localized shear band domain in a dense specimen is inspected. The analysis of elastic processes suggests a maximum capacity for storing elastic energy, giving rise to a phase transition from a homogeneous state to a heterogeneous one. This phase transition is marked by a significant release of elastic energy associated with plastic dissipation. The elastic-to-plastic energy transfer is shown to be a key ingredient to reach the stationary state regime characterized by a unique dynamic equilibrium. It is signaled by the constant ratios of elastic storage and plastic dissipation over the available energy, whatever the initial density of granular assemblies. Finally, the energy processes inside the shear band domain are shown to be largely dominated by intense plastic dissipation. This suggests that the shear band acts as an optimal dissipative structure in dense specimens where elastic mechanisms continue to be active at a much higher level than they are in the outside shear band domain.

颗粒集 合体是复杂材料的一个示例，当它们受到特定载荷时，可能会出现意想不到的宏观特性。这种复杂性是由颗粒重新排列所导致的巨大几何无序造成的，并在接触处产生塑性耗散。这种与全局几何无序相关的局部耗散可能是造成各种宏观特征的关键因素，例如致密颗粒集 合体中的应变局部化导致剪切带的形成。本手稿基于离散元素法（DEM），研究了致密和疏松装配体沿双轴加载路径的颗粒装配体微观尺度的能量过程。对致密试样中的局部剪切带域进行了检测。对弹性过程的分析表明，储存弹性能量的能力达到了最大值，从而产生了从均质状态到异质状态的相变。这种相变的特点是与塑性耗散相关的弹性能量的显著释放。从弹性到塑性的能量转移是达到以独特的动态平衡为特征的静止状态的关键因素。无论颗粒集 合体的初始密度如何，弹性存储和塑性耗散与可用能量的恒定比率都表明了这一点。最后，剪切带域内的能量过程主要由强烈的塑性耗散主导。这表明剪切带在致密试样中是一种最佳耗散结构，其弹性机制的持续活跃程度远高于剪切带域外部。

Journal of the Mechanics and Physics of Solids

Initializing intragranular residual stresses within statistically equivalent microstructures for crystal plasticity simulations

Ritwik Bandyopadhyay, Krzysztof S. Stopka, Michael D. Sangid

doi:10.1016/j.jmps.2023.105529

为晶体塑性模拟初始化统计等效微结构中的粒内残余应力

We propose a mechanics framework to compute intragranular or type III residual stress within a polycrystalline aggregate for which experimental characterization of residual stress is unknown. The framework is built upon the inter-relationship between intragranular misorientation (IGM), geometrically necessary dislocation (GND), and long-range internal stress. Given a spatial distribution of IGM, we first calculate the spatial distribution of GND density; subsequently, we calculate the internal stress and strain fields due to the GND distribution. For demonstration, we consider a synthetic microstructure of a hexagonal close-packed material, namely Ti-7Al, wherein the grain size and orientation distributions are statistically equivalent to the distributions obtained via experimental characterization. We refer to this microstructure as a statistically equivalent microstructure (SEM). In an SEM, each grain is usually treated as a pristine crystal and therefore, the SEM contains no IGM. We propose a technique to introduce IGM within the SEM and, subsequently, calculate the GND density and residual stress distributions in a consistent manner. In the process, we ensure that statistical distributions of the IGM and residual strain within the SEM are statistically equivalent to the same obtained from the experimental characterization of Ti-7Al. While establishing statistically equivalent residual stress, the thermal effects during processing of Ti-7Al are implicitly taken into account. Next, we perform crystal plasticity finite element simulations to demonstrate the implications of the initialization of IGM and type III residual stress. Although the IGM and residual stress are related, the results suggest that the type III residual stress initialization has a much more pronounced effect on microplasticity-driven damage mechanisms, such as high cycle fatigue, even within a well-annealed material such as Ti-7Al, thereby emphasizing the need for its initialization for microstructure-sensitive fatigue analysis. Finally, we demonstrate that initializing thermally induced residual stress within Ti-7Al SEM through a cooling simulation, accounting for the anisotropic nature of the coefficient of thermal expansion, yields a grain-averaged residual stress distribution statistically similar to that obtained from our framework and is a special case of the type II residual stress implementation.

我们提出了一个力学框架，用于计算多晶体内部的晶内应力或 III 型残余应力，该多晶体的残余应力实验特征尚不清楚。该框架建立在粒内错向（IGM）、几何必要位错（GND）和长程内应力之间的相互关系之上。给定 IGM 的空间分布，我们首先计算 GND 密度的空间分布；然后计算 GND 分布引起的内应力和应变场。为了演示，我们考虑了一种六方紧密堆积材料（即 Ti-7Al ）的合成微观结构，其中的晶粒尺寸和取向分布在统计上等同于通过实验表征获得的分布。我们将这种微观结构称为统计等效微观结构（SEM）。在 SEM 中，每个晶粒通常被视为原始晶体，因此 SEM 中不包含 IGM。我们提出了一种在 SEM 中引入 IGM 的技术，并随后以一致的方式计算 GND 密度和残余应力分布。在此过程中，我们确保扫描电子显微镜内的 IGM 和残余应变的统计分布在统计学上等同于从 Ti-7Al 的实验表征中获得的相同分布。在建立统计等效残余应力的同时，还隐含地考虑了 Ti-7Al 加工过程中的热效应。接下来，我们进行了晶体塑性有限元模拟，以证明初始化 IGM 和 III 型残余应力的影响。虽然 IGM 和残余应力是相关的，但结果表明 III 型残余应力初始化对微塑性驱动的损伤机制（如高循环疲劳）具有更明显的影响，即使是在 Ti-7Al 这种退火良好的材料中也是如此，从而强调了在进行微结构敏感疲劳分析时对其进行初始化的必要性。最后，我们证明了通过冷却模拟初始化 Ti-7Al SEM 中的热诱导残余应力，考虑到热膨胀系数的各向异性，可得到与我们的框架所得到的残余应力分布在统计上相似的晶粒平均分布，是第二类残余应力实施的一个特例。

Mechanics of Materials

Implicit multiscale finite element analysis of polymer physics-based multiscale constitutive model for elastomers

Jiwon Jung, Gun Jin Yun

doi:10.1016/j.mechmat.2023.104904

基于聚合物物理的弹性体多尺度构成模型的隐式多尺度有限元分析

This paper proposes a multiscale visco-hyperelastic constitutive model that can predict the material behavior bridging molecular properties to response at the continuum level and its integration within implicit finite element analysis. The proposed model incorporates all parameters having actual physical meaning obtained from molecular simulations based on the tube theory. Despite the advantages that the constitutive equation was determined from molecular network characteristics, applications of the model have been restricted to the simple shape of Finite Element (FE) models with a few cases of specific deformations, owing to its complexity and absence of the implicit formulation. Therefore, the application of the model to the 3D implicit FE analysis with a tangent stiffness was proposed by applying numerical differentiation with the complex step derivative approximation (CSDA) method. Combined with the Neo-Hookean hyperelasticity model, the results from the example analysis applied to the tensile specimen model were examined to manifest the visco-hyperelastic characteristics of elastomers under cyclic loading, stability of the analysis, and further discussion on the visco-hyperelastic constitutive model were proposed.

本文提出了一种多尺度粘弹性-超弹性构造模型，该模型可以预测材料行为，将分子特性与连续层面的响应联系起来，并将其集成到隐式有限元分析中。该模型包含了基于管理论的分子模拟中获得的所有具有实际物理意义的参数。尽管该模型的构成方程是根据分子网络特征确定的，但由于其复杂性和缺乏隐式表述，该模型的应用仅限于有限元（FE）模型的简单形状和少数特定变形情况。因此，通过使用复杂阶梯导数近似（CSDA）方法进行数值微分，提出了将该模型应用于具有切线刚度的三维隐式 FE 分析。结合 Neo-Hookean 超弹性模型，对应用于拉伸试样模型的实例分析结果进行了检验，以体现弹性体在循环加载下的粘-超弹性特性、分析的稳定性，并对粘-超弹性构成模型提出了进一步的讨论。

Thin-Walled Structures

Research on somatosensory shock wave pressure measurement method based on PVDF film

Yongjian Zhang, Changan Di, Peng Peng, Dahai Li, Xinge Si, Bin Ji

doi:10.1016/j.tws.2023.111520

基于 PVDF 膜的体感冲击波压力测量方法研究

Piezoelectric pressure sensors and human tissue have different pressure impedance coefficients, which results in a discrepancy when accurately measuring the real somatosensory shock wave pressure (SSWP). The aim of this research is to develop a method that can realistically characterize SSWP measurements. To achieve this, the study uses the finite element method to analyze the response of both human tissue and piezoelectric pressure sensors to the same shock wave load. The numerical simulation results show a significant difference in the pressure response between the two under identical shock wave loads. Based on this, the working mode and equivalent model of Polyvinylidene fluoride (PVDF) film for measuring SSWP are determined. Using the finite element method, the same shock wave pressure load is applied to PVDF films with thicknesses of 20μm, 50μm, 100μm, as well as human tissue. The results reveal a good agreement between the pressure response of the PVDF film and human tissue. As the thickness of the PVDF film decreases, particularly at 20μm thickness, the accuracy improves. Additionally, a comparative experiment is conducted using a bionic dummy model. The outcomes indicate that PVDF film is more stable than piezoelectric pressure sensors and can accurately characterize the real SSWP, aligning with the numerical simulation results by up to 98.4%.

压电压力传感器和人体组织具有不同的压力阻抗系数，这导致在精确测量真实体感冲击波压力（SSWP）时存在差异。本研究的目的是开发一种能真实描述 SSWP 测量值的方法。为此，研究采用有限元法分析人体组织和压电压力传感器对相同冲击波负载的响应。数值模拟结果表明，在相同的冲击波负载下，两者的压力响应存在显著差异。在此基础上，确定了用于测量 SSWP 的聚偏二氟乙烯（PVDF）薄膜的工作模式和等效模型。利用有限元方法，对厚度分别为 20μm、50μm、100μm 的聚偏二氟乙烯（PVDF）薄膜和人体组织施加了相同的冲击波压力载荷。结果表明，PVDF 膜和人体组织的压力响应非常一致。随着 PVDF 薄膜厚度的减小，尤其是 20μm 厚度时，精确度有所提高。此外，还使用仿生假人模型进行了对比实验。结果表明，PVDF 膜比压电压力传感器更稳定，能准确表征真实的 SSWP，与数值模拟结果的吻合度高达 98.4%。

Ground shock attenuation performances of wire-rope-based meta-isolators

Yang Liu, Dongyu Shi, Yu Li, Sanfeng Liu, Huguang He, Hailong Chen, Hualin Fan

doi:10.1016/j.tws.2023.111538

基于钢丝绳的元隔离器的接地冲击衰减性能

In this research, two types of novel meta-isolators were designed based on traditional wire-rope isolators and made by embedding mass-spring resonators into the wire-rope isolator. Measurement methods to reveal attenuation abilities of these meta-isolators were suggested through quasi-static cyclic loading tests, shaking table tests, and in-field explosion experiments. In the quasi-static tests, meta-isolators have greater hysteresis area under the same excitation displacement, which represents much greater energy consumption. Using shaking table tests and measurement, the vibration attenuation ability of the meta-isolators is improved in the designed resonant frequency, and the response amplitudes are significantly reduced compared with the conventional wire-rope isolators. Blast-induced ground shock experiments reveal that the meta-isolators indeed have an advantage over the conventional isolators in the aspect of shock resistance and the attenuation efficiency exceeds 98%, providing a new idea and reference for protective engineering.

本研究在传统钢丝绳隔振器的基础上，通过在钢丝绳隔振器中嵌入质量弹簧谐振器，设计了两种新型元隔振器。通过准静态循环加载试验、振动台试验和现场爆炸实验，提出了揭示这些元隔离器衰减能力的测量方法。在准静态试验中，元隔离器在相同的激励位移下具有更大的滞后面积，这意味着更高的能量消耗。通过振动台试验和测量，元隔振器在设计共振频率下的减振能力得到提高，响应振幅比传统钢丝绳隔振器显著减小。爆炸引起的地面冲击实验表明，元隔振器在抗冲击方面确实比传统隔振器更有优势，衰减效率超过 98%，为防护工程提供了新的思路和参考。