Complex materials play an essential role in many applications, ranging from turbine blades, car chassis, computer and cell phone cases, battery systems, and stretchable and wearable electronics to biomedical applications. Those materials often operate and must maintain their high performance in harsh environments. The advancement of computational methods at multiple scales opens new possibilities for the design of such complex materials and the optimization of their intrinsic properties under extreme events. The bridging of different length and time scales, though, still represents an area of active research with many unresolved challenges. For example, material degradation is considered as a typical multiscale process, controlled by nanoscale defects, highly affecting the macroscopic material response. In order to discuss the methods of modeling of multiphysics aspects of complex materials behavior, the International Symposium on Multiscale Computational Analysis of Complex Materials was organized on August 29–31, 2017, at the Technical University of Denmark/DTU, Copenhagen. The symposium topics included multiscale multiphysics modeling of materials; computational materials science; micromechanics of materials; scale bridging and homogenization; materials under extreme environments; hierarchical, biological, and natural materials; and nanomaterials. Several selected papers from this symposium are presented in this issue of the International Journal for Multiscale Computational Engineering . In the paper “A Damage Particle Method for Smeared Modeling of Brittle Fracture,” by Jiun-Shyan Chen (University of California, San Diego), a new damage particle method based on the smeared fracture modeling approach is presented which allows the capturing of moving strong discontinuities. This work was presented at the symposium as a keynote presentation in the Multiscale Composites session. The paper “A Multi-Scale/Multi-Domain Model for the Failure Analysis of Masonry Walls,” by Professor Patrizia Trovalusci (University of Roma, Italy) and her colleagues, was a keynote presentation in the Structured Materials session. In this paper, a novel multiscale/multidomain approach for nonlinear analysis of masonries is presented. In the Porous and Granular Materials session, the paper by Professor Waiching Sun (Columbia University), “An Adaptive Reduced-Dimensional Discrete Element Model for Dynamic Responses of Granular Materials with HighFrequency Noises,” was presented. In this paper, a dimensional-reduction framework based on proper orthogonal decomposition (POD) for nondissipative explicit dynamic discrete element method (DEM) simulations is presented. The approach allows faster and more efficient discrete element simulations. Several presentations were made in the Crystalline Materials session at the symposium. In the paper “Modelling Plastic Deformation of Nano/Submicron-Sized Tungsten Pillars Under Compression” by Shuozhi Xu (University of California, Santa Barbara), coarse-grained atomistic simulations via the concurrent atomistic-continuum (CAC) method are performed to investigate compressive deformation of nano/submicron-sized pillars in body-centered cubic (BCC) tungsten. This work is the first attempt to simulate BCC systems using the CAC method and highlights the significance of the surface roughness in the deformation of the samples. An important direction of computational mechanics of materials is multifunctional materials, e.g., with electrical, sensing functionality and high mechanical performance. In this area, two papers were selected for this issue. In the paper “Variationally Consistent Computational Homogenization of Micro-Electro-Mechanics at Finite Deformations,” by Professor Marc-Andre Keip and colleagues (University of Stuttgart, Germany), a variationally consistent approach of computational homogenization to large-deformation microelectromechanics is presented. A phase-field model for microstructure evolution in ferroelectrics is linked to an electromechanical macrocontinuum. Krzysztof Grabowski and colleagues from AGH University of Science and Technology, Poland, developed a multiscale model to predict mechanical properties of carbon nanotube reinforced sensing composites in their paper “Multiscale Model-Based Sensitivity Analysis of Mechanical Response of CNT/Polymer for Strain Sensing.”

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社论

复杂材料在许多应用中发挥着重要作用，从涡轮叶片、汽车底盘、计算机和手机外壳、电池系统、可拉伸和可穿戴电子产品到生物医学应用。这些材料经常运行并且必须在恶劣的环境中保持其高性能。多尺度计算方法的进步为这种复杂材料的设计和极端事件下其内在特性的优化开辟了新的可能性。然而，不同长度和时间尺度的桥接仍然代表着一个活跃的研究领域，其中有许多未解决的挑战。例如，材料降解被认为是典型的多尺度过程，受纳米级缺陷控制，高度影响宏观材料响应。为了讨论复杂材料行为的多物理场方面的建模方法，复杂材料多尺度计算分析国际研讨会于 2017 年 8 月 29 日至 31 日在丹麦技术大学/DTU 哥本哈根举行。研讨会主题包括材料的多尺度多物理场建模；计算材料科学；材料的微观力学；规模桥接和同质化；极端环境下的材料；等级、生物和天然材料；和纳米材料。本次研讨会的几篇精选论文发表在本期《国际多尺度计算工程杂志》上。在Jiun-Shyan Chen（加州大学圣地亚哥分校）的论文“A Damage Particle Method for Smeared Modeling of Brittle Fracture”中，提出了一种基于涂抹裂缝建模方法的新损伤粒子方法，该方法允许捕获移动的强不连续性。这项工作在研讨会上作为多尺度复合材料会议的主题演讲进行了介绍。Patrizia Trovalusci 教授（意大利罗马大学）及其同事的论文“用于砌体墙失效分析的多尺度/多域模型”是结构材料会议的主题演讲。在本文中，提出了一种用于砌体非线性分析的新型多尺度/多域方法。在多孔和颗粒材料环节，孙伟清教授（哥伦比亚大学）发表了论文“An Adaptive Reduced-Dimensional Discrete Element Model for Dynamic Responses of Granular Materials with HighFrequency Noises”。在本文中，提出了一种基于适当正交分解 (POD) 的降维框架，用于非耗散显式动态离散元方法 (DEM) 模拟。该方法允许更快和更有效的离散元件仿真。在研讨会的晶体材料会议上做了一些演讲。在 Shuozhi Xu（加州大学圣巴巴拉分校）的论文“压缩下纳米/亚微米尺寸钨柱的塑性变形建模”中，通过并发原子连续体 (CAC) 方法进行粗粒度原子模拟以研究压缩体心立方 (BCC) 钨中纳米/亚微米尺寸柱的变形。这项工作是首次尝试使用 CAC 方法模拟 BCC 系统，并突出了表面粗糙度在样品变形中的重要性。材料计算力学的一个重要方向是多功能材料，例如，具有电气、传感功能和高机械性能。在这方面，本期选择了两篇论文。在 Marc-Andre Keip 教授及其同事（德国斯图加特大学）的论文“有限变形下微机电的变相一致计算均质化”中，提出了一种对大变形微机电进行计算均质化的变分一致方法。铁电体微观结构演化的相场模型与机电宏观连续体相关联。