今日更新:International Journal of Solids and Structures 1 篇,Journal of the Mechanics and Physics of Solids 1 篇,Mechanics of Materials 1 篇,Thin-Walled Structures 1 篇
Multiscale simulation of polymer curing of composites combined mean-field homogenisation methods at large strains
Peter Lenz, Rolf Mahnken
doi:10.1016/j.ijsolstr.2023.112642
复合材料聚合物固化的多尺度模拟,结合大应变下的均场均质化方法
This work introduces a coupled thermo-chemo-mechanical framework for simulating the polymerisation process of composites, accounting for large strains. The framework encompasses the microscale, mesoscale and, macroscale. The microscale represents a step-growth polymerisation mechanism, which is modelled as a system of multiple growing spheres. These spheres are further decomposed into concentric layers of solid, resin, and curing agent material. At the mesoscale, the composite is divided into inclusions and the polymer matrix. The macroscale is considered as a homogeneous material. In order to describe the behaviour of the heterogeneous scales, mean-field homogenisation methods are employed. These methods have been developed before for linear elastic materials. However, considering finite deformations, a special treatment is necessary to accurately account for the effects of such deformations. Effective properties at all scales are obtained using the Mori–Tanaka, Voigt, Reuss, and Voigt–Reuss–Hill average mean-field homogenisation method. The results demonstrate how the different homogenisation methods influence the curing process and, consequently, the macroscopic response of the composite material.
这项研究引入了一个热-化学-机械耦合框架,用于模拟复合材料的聚合过程,并考虑到大应变。该框架包括微观尺度、中观尺度和宏观尺度。微观尺度代表一种阶跃生长聚合机制,它被模拟为一个由多个生长球组成的系统。这些球体进一步分解成固体、树脂和固化剂材料的同心层。在中尺度上,复合材料分为夹杂物和聚合物基体。宏观尺度被视为均质材料。为了描述异质尺度的行为,采用了均场均质化方法。这些方法以前是针对线性弹性材料开发的。然而,考虑到有限变形,有必要采用特殊的处理方法来准确地解释这种变形的影响。使用 Mori-Tanaka、Voigt、Reuss 和 Voigt-Reuss-Hill 平均均场均质法获得了所有尺度上的有效特性。结果表明了不同的均质化方法如何影响固化过程,进而影响复合材料的宏观响应。
Enhancing toughness through geometric control of the process zone
Sage Fulco, Michal K. Budzik, Kevin T. Turner
doi:10.1016/j.jmps.2024.105548
通过对加工区的几何控制提高韧性
Material architecture provides an opportunity to alter and control the fracture process zone shape and volume by redistributing the local stresses at a crack tip. Properly designed structures can enlarge the plastic zone and enhance the effective toughness. Here, we use a pillar array as a model structure to demonstrate how variations in geometry at a crack tip control the size and shape of the plastic zone and can be used to engineer the effective toughness. Elastic–plastic finite element simulations are used to show how the pillar width, spacing, and height can be varied to tailor the size and shape of the plastic zone. A set of analytical mechanics models that accurately estimate the shape, volume, and resulting toughness as a function of the base material properties and geometry are also presented. A case study extends the analysis to sets of non-regular pillar arrays to illustrate how architecture can be used to alter toughness along the crack path.
材料结构通过重新分配裂纹尖端的局部应力,为改变和控制断裂过程区的形状和体积提供了机会。设计合理的结构可以扩大塑性区并提高有效韧性。在此,我们以支柱阵列为模型结构,展示了裂纹尖端几何形状的变化如何控制塑性区的大小和形状,并可用于设计有效韧性。我们使用弹塑性有限元模拟来展示如何通过改变支柱的宽度、间距和高度来调整塑性区的大小和形状。此外,还介绍了一套分析力学模型,该模型可准确估计形状、体积和由此产生的韧性与基础材料特性和几何形状的函数关系。案例研究将分析扩展到非规则支柱阵列,以说明如何利用结构沿裂纹路径改变韧性。
Mean field homogenization schemes using averages of stress, strain and strain energy density and applications
Tao Fu, Chuanying Li, Hao Hu, Xianghe Peng
doi:10.1016/j.mechmat.2024.104911
使用应力、应变和应变能密度平均值的平均场均质化方案及其应用
The average of stress (AS) and average of strain (AN) were often used in the development of conventional mean-field homogenization (MFH) schemes, but their correlation with the average of strain energy density (AE) has rarely been discussed. In this work, we examined the correlations of AE with AS and AN, and found that AE can be reduced to the product of AS or AN under uniform boundary stress or linear surface displacement associated with a uniform strain field. By introducing a reference matrix and using any two among AE, AS and AN, three MFH schemes were developed: NS (using AN and AS); NE (using AN and AE); and SE (using AS and AE). Following the concept of the Mori-Tanaka's (MT) method, three MFH schemes obtained above were reduced to MT-NS, MT-NE and MT-SE, respectively. Effective elastic properties of composites consisting of isotropic elastic matrices and spherical isotropic elastic inclusions were predicted using these schemes and compared with experimental results. The comparison revealed that MT-SE and MT-NS can reasonably replicate the experimental results in the case of moderate particle volume fractions and ratios between the Young's moduli of matrix and the reinforcement particles, demonstrating the validity of the MFH schemes. This work is significant because it not only clarifies the correlation of AE with AN and AS, but also provides more options for the development of MFH schemes, which can enrich the theory and methods for the analysis of the effective properties of composites.
应力平均值(AS)和应变平均值(AN)经常被用于传统均场均质化(MFH)方案的开发,但它们与应变能量密度平均值(AE)的相关性却很少被讨论。在这项工作中,我们研究了 AE 与 AS 和 AN 的相关性,发现在均匀边界应力或与均匀应变场相关的线性表面位移条件下,AE 可以简化为 AS 或 AN 的乘积。通过引入参考矩阵并使用 AE、AS 和 AN 中的任意两个,开发出三种 MFH 方案:NS(使用 AN 和 AS);NE(使用 AN 和 AE);SE(使用 AS 和 AE)。按照森田中(Mori-Tanaka,MT)方法的概念,上述三种 MFH 方案分别简化为 MT-NS、MT-NE 和 MT-SE。利用这些方案预测了由各向同性弹性基体和球形各向同性弹性夹杂物组成的复合材料的有效弹性特性,并与实验结果进行了比较。比较结果表明,在颗粒体积分数和基体与增强颗粒的杨氏模量比适中的情况下,MT-SE 和 MT-NS 可以合理地复 制实验结果,证明了 MFH 方案的有效性。这项工作意义重大,不仅阐明了 AE 与 AN 和 AS 的相关性,还为 MFH 方案的开发提供了更多选择,丰富了复合材料有效性能分析的理论和方法。
Numerical simulation of corroded circular hollow section steel columns: A corrosion evolution approach
Yun Zhao, Xuhong Zhou, Fei Xu, Tak-Ming Chan
doi:10.1016/j.tws.2024.111594
腐蚀圆形空心截面钢柱的数值模拟:腐蚀演变方法
This study introduces a numerical simulation method for corroded circular hollow section steel columns, utilising a newly developed corrosion evolution model. This model was formulated by characterising the corrosion morphology and calibrating parameters throughout the entire corrosion process. An interpolation method was implemented to estimate the number of corrosion pits, based on experimentally measured corrosion ratios. Consequently, this allowed for the numerical prediction of the time-varying corrosion morphologies. Finite element (FE) models, incorporating this corrosion evolution model, were constructed. These corroded column models underwent validation through comparison with experimental findings. To further establish the effectiveness of the proposed FE models in predicting the structural behaviour of corroded members, FE models were also developed using the traditional uniform thickness reduction approach for comparative analysis. The results revealed that the proposed FE models for corroded structures offer a more accurate prediction of mechanical performance, particularly in instances of severe corrosion damage.
本研究利用新开发的腐蚀演化模型,介绍了腐蚀圆形空心截面钢柱的数值模拟方法。该模型是通过描述整个腐蚀过程中的腐蚀形态和校准参数而建立的。根据实验测得的腐蚀比,采用内插法估算腐蚀坑的数量。因此,这样就可以对随时间变化的腐蚀形态进行数值预测。结合这种腐蚀演变模型,构建了有限元 (FE) 模型。这些腐蚀柱模型通过与实验结果的对比进行了验证。为了进一步确定所提出的有限元模型在预测腐蚀构件结构行为方面的有效性,还使用传统的均匀减厚方法开发了有限元模型,以进行对比分析。结果表明,针对腐蚀结构提出的有限元模型能够更准确地预测机械性能,尤其是在严重腐蚀损坏的情况下。