今日更新:International Journal of Solids and Structures 1 篇,International Journal of Plasticity 1 篇,Thin-Walled Structures 2 篇
An indentation method to determine the constitutive parameters of hyperelastic films under large deformation: Theoretical model, experiments and simulations
Haoyuan Che, Martine Ben Amar, Wei Zhu, Shengjun Fan, Jinsong Leng, Fei Jia, Yanju Liu
doi:10.1016/j.ijsolstr.2024.113007
一种确定大变形下超弹性薄膜本构参数的压痕方法:理论模型、实验与仿真
The characterization of the mechanical properties of soft films is of great importance for their applications. In our previous research, we demonstrate the existence of a maximum load occurring during the indentation process of a perforated film by a spherical indenter. Based on this result, an approach to obtain the shear modulus of the film material using the method of finite element analysis has been proposed. However, our previous work does not consider the effect of friction between the film and the indenter, which has a significant influence on the value of the maximum load. Here, a theoretical model is presented which takes into account the role of friction. The reliability and accuracy of the theoretical model are validated by comparison with simulations and experimental results. In addition, the indenter eccentricity and round hole shape deviations which commonly occur in actual indentation tests, are investigated by combining indentation test measurements with finite element analysis. The performance of this method on porous films is also analyzed experimentally and numerically. The results reveal that this indentation method is still effective for porous films. This work provides a fundamental understanding of the mechanism of the indentation method and is expected to provide a new perspective for local characterization of films, even with multiple holes.
软膜力学性能的表征对其应用具有重要意义。在我们之前的研究中,我们证明了球形压头在穿孔膜压痕过程中存在最大载荷。在此基础上,提出了一种利用有限元分析方法求得薄膜材料剪切模量的方法。然而,我们之前的工作没有考虑薄膜和压头之间的摩擦的影响,这对最大载荷的值有很大的影响。在这里,提出了一个考虑摩擦作用的理论模型。通过与仿真和实验结果的比较,验证了理论模型的可靠性和准确性。此外,将压痕试验测量结果与有限元分析相结合,对实际压痕试验中常见的压痕偏心和圆孔形状偏差进行了研究。实验和数值分析了该方法在多孔膜上的性能。结果表明,这种压痕方法对多孔膜仍然是有效的。这项工作提供了对压痕方法机制的基本理解,并有望为具有多个孔的薄膜的局部表征提供新的视角。
3D microstructure-based modelling of ductile damage at large plastic strains in an aluminum sheet
Abhishek Sarmah, Shahryar Asqardoust, Mukesh K Jain, Hui Yuan
doi:10.1016/j.ijplas.2024.104088
基于三维微观结构的大塑性应变下铝板韧性损伤模型
Damage initiation in high-strength aluminum alloys with a precipitate-rich matrix is typically particle-driven. In AA7075-O temper, particle cracking and decohesion are the primary void nucleation mechanisms. However, the impact of particle-induced voiding on subsequent void growth and coalescence remains inadequately understood. Given that void growth and coalescence are inherently three-dimensional (3D) phenomena, conventional two-dimensional microstructure-based numerical models fail to accurately capture these damage evolution processes. The current work investigates void growth and coalescence phenomena in AA7075-O by developing 3D finite element (FE) real microstructure based models, created from plasma focused ion beam-scanning electron (PFIB-SEM) tomography and 3D electron back scattered diffraction (3D-EBSD). The models incorporate three key damage processes: particle cracking, particle decohesion, and matrix damage, to examine their effects on void growth and coalescence behavior in AA7075-O. Additionally, the influence of aluminum matrix grains on damage evolution in AA7075-O is explored. Complementary multi-scale modeling tools, along with in-situ scanning electron microscopy (SEM) and in-situ micro-X-ray computed tomography (μXCT), were employed for validation and supplementary insights. It is shown that 3D RVEs can capture the general 3D experimental trends in plastic heterogeneity and damage development at the microstructural length scale. Also, void growth and coalescence is influenced by the local stress fields, which in turn is dictated by particle morphology, particle cracking and decohesion. Particle cracking can accelerate the final specimen fracture, while particle decohesion promotes void growth but delays final coalescence. Void coalescence is shown to occur through void sheeting mechanism while the influence of grain characteristics on ductile void damage progression is found to be relatively limited.
在富含析出物的高强度铝合金中,损伤的起裂通常是由颗粒驱动的。在AA7075-O回火中,颗粒开裂和脱聚是主要的空穴形核机制。然而,颗粒诱导的空穴对随后的空穴生长和合并的影响仍然没有得到充分的了解。由于空洞生长和聚并是固有的三维(3D)现象,传统的基于二维微观结构的数值模型无法准确捕捉这些损伤演化过程。目前的工作是通过建立基于等离子体聚焦离子束扫描电子(PFIB-SEM)断层扫描和3D电子背散射衍射(3D- ebsd)的三维有限元(FE)真实微观结构模型来研究AA7075-O中的空洞生长和聚并现象。该模型包括三个关键损伤过程:颗粒开裂、颗粒脱黏和基体损伤,以研究它们对AA7075-O中空洞生长和聚结行为的影响。此外,还探讨了铝基晶粒对AA7075-O损伤演化的影响。互补的多尺度建模工具,以及原位扫描电子显微镜(SEM)和原位微x射线计算机断层扫描(μXCT),用于验证和补充见解。结果表明,三维RVEs可以在微观结构长度尺度上捕捉塑性非均质性和损伤发展的一般三维实验趋势。此外,孔隙的生长和聚并受局部应力场的影响,而局部应力场又受颗粒形态、颗粒开裂和脱黏的影响。颗粒开裂可加速试样的最终断裂,而颗粒脱黏可促进空洞的生长,但会延迟试样的最终聚并。孔洞聚并是通过孔洞片化机制发生的,而晶粒特征对塑性孔洞损伤进展的影响相对有限。
Post-fire behavior and resistances of S890 ultra-high strength steel circular hollow section beam–columns
Jiahao Zhang, Hua Yang, Andi Su
doi:10.1016/j.tws.2024.112322
S890超高强度钢圆空心截面梁柱的火后性能及耐火性能
An experimental and numerical modeling program was carried out to investigate the post-fire structural behavior and residual resistances of S890 ultra-high strength steel (UHSS) circular hollow section (CHS) beam–columns after exposure to elevated temperatures and presented in this paper. Eighteen CHS beam–column specimens were tested, with heating, soaking and cooling of specimens, post-fire tensile coupon tests as well as measurements of initial global geometric imperfections firstly performed. Finite element (FE) models were developed and validated against the available experimental results, and then adopted for generating further numerical data covering a wider spectrum of member lengths, cross-sectional dimensions and loading combinations to expand the data pool. Owing to the absence of design provisions for steel structures after exposure to elevated temperatures, the relevant ambient temperature design interaction curves outlined in the current European, American and Australian specifications are evaluated for their applicability to S890 UHSS CHS beam–columns after exposure to elevated temperatures, with post-fire material properties used. The assessment results revealed that the codified provisions in the European, American and Australian specifications can lead to safe but slightly conservative resistance predictions for S890 UHSS CHS beam–columns after exposure to elevated temperatures, except for a few unsafe data points (for the elevated temperature of 800 °C) predicted by the Australian standard.
本文采用实验和数值模拟方法研究了S890超高强度钢(UHSS)圆空心截面(CHS)梁柱在高温下的火灾后结构行为和残余抗力。对18个CHS梁柱试件进行了试验,首先进行了试件的加热、浸泡和冷却、火灾后的张拉副试验以及初始全局几何缺陷测量。建立了有限元模型,并根据现有的实验结果进行了验证,然后采用有限元模型生成了涵盖更广泛的构件长度、截面尺寸和加载组合的进一步数值数据,以扩大数据池。由于钢结构在高温下的设计缺乏规定,我们评估了当前欧洲、美国和澳大利亚规范中概述的相关环境温度设计交互曲线对S890 UHSS CHS梁柱在高温下的适用性,并使用了火灾后的材料性能。评估结果显示,除了澳大利亚标准预测的一些不安全数据点(对于800°C的高温)外,欧洲、美国和澳大利亚规范中的法规规定可以导致S890 UHSS CHS梁柱暴露于高温后的安全但略保守的阻力预测。
Dynamic analysis of stepped functionally graded conical shells with general boundary restraints using Jacobi polynomials-Ritz method
Lin Lu, Cong Gao, Jiawei Xu, Haichao Li, Jiajun Zheng
doi:10.1016/j.tws.2024.112304
用Jacobi多项式- ritz方法分析具有一般边界约束的阶梯功能梯度圆锥壳的动力
This study investigates the dynamic behaviors of stepped functionally graded conical shells under general boundary restraints. The properties of functionally graded material change continuously through the thickness in the framework of the general four parameter power-law distributions. A numerical analysis framework is formulated utilizing the Jacobi polynomials-Ritz method. The construction of the dynamic model incorporates the first-order shear deformation theory, domain decomposition approach and virtual spring method, with the introduction of the Jacobi orthogonal polynomials to delineate displacement functions. Through the Ritz method, both the free and forced vibrational behaviors of the structure are delineated. Moreover, the vibration response of the structure in time domain is ascertained utilizing the Newmark-β integral approach. This study offers a detailed examination of the influence exerted by factors including truncation number, and the Jacobi parameter on the convergence of the presented method. The veracity of the current approach is verified by juxtaposing its findings with those derived from the Finite Element Method and existing literatures. Additionally, the investigation explores the dynamic features of the stepped structure subject to different construction parameters, boundary restraints, and power-law distribution, as demonstrated through a comprehensive set of numerical examples.
研究了阶梯式功能梯度锥形壳在一般边界约束下的动力特性。在一般四参数幂律分布框架下,功能梯度材料的性能随厚度的变化而连续变化。利用雅可比多项式-里兹方法建立了数值分析框架。动力学模型的构建结合了一阶剪切变形理论、区域分解法和虚拟弹簧法,并引入了雅可比正交多项式来描述位移函数。通过Ritz方法,描述了结构的自由振动和强迫振动行为。此外,利用Newmark-β积分法确定了结构的时域振动响应。本文详细考察了截断数和Jacobi参数等因素对所提方法收敛性的影响。通过将现有方法的结果与有限元法和现有文献的结果并列验证了当前方法的准确性。此外,通过一组综合的数值算例,研究了不同施工参数、边界约束和幂律分布下阶梯结构的动力特性。