| 基于均匀化理论的复合材料安定性分析方法 |
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| 作者姓名： | 秦方 张乐乐 黄松华 陈耕 |
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| 作者单位： | 1.北京交通大学机械与电子控制工程学院，北京 100044 |
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| 基金项目： | 国家自然科学基金资助项目（51475036） |
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| 摘 要： | 周期性非均质复合材料具有微观结构特征，需要均匀化理论进行宏观和微观的多尺度分析来研究其性能表现。针对其耐久强度性能，应用塑性极限安定下限定理，特别分析了其在长期交变载荷下的安定状态。结合工程应用目标，提出一种全新的代表性单元边界条件，结合圆锥二次优化算法进行数值计算，可以从材料微结构和组分性能出发，经过弹性应力场求解确定位移边界载荷数值，最终由优化求解得到复合材料板材的面内塑性性能容许域。所求得的应力域以单向应力为基，可根据结构宏观的单向应力状态变化幅值直接进行安定状态与否的判定。通过文中的多个算例，验证了所编写的软件及计算流程的可行性及数值准确性，展示了该方法在工程模型中的应用场合和工程实践意义。
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| 关 键 词： | 复合材料 极限安定分析 均匀化理论 代表性单元 圆锥二次优化 |
| 收稿时间： | 2019-01-06 |
Shakedown analysis method for composites based on homogenization theory |
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| Affiliation: | 1.School of Mechanical, Electronic and Control Engineering, Beijing Jiaotong University, Beijing 100044, China2.Institute for Materials Applications in Mechanical Engineering, RWTH Aachen University, Aachen 52062, German |
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| Abstract: | Direct methods of plastic analysis are widely used in composites analysis to determine material strength for safety assessment or lightweight optimization design. Multi-scale processing of periodic heterogeneous composite material is needed due to its existing of microstructure. The standard method is to determine the macroscopic properties from the calculation results of microcosmic representative volume elements (RVEs) by using the homogenization theory. However, in current practice, there are some disadvantages of transforming the micro strain domain to the macro stress shakedown domain when considering multiple external loads. The domain cannot fully demonstrate the shakedown condition, and it is impossible to evaluate a known loading combination only from the knowledge of whether the load leads to the shakedown state. To overcome this disadvantage, a new comprehensive approach was proposed to enhance endurance limit strength of composites under variable loads for long term. Considering the example of in-plane strength analysis, for microcosmic RVEs, a new set of boundary condition was defined in the form of uniform strain. The boundary condition was derived from the elastic response under unit loads by using Hook’s law and stiffness matrix. The resulting elastic stress field was used later for plastic shakedown analysis. Based on the lower bound theorem of plastic mechanics, optimization programming for load factor was performed, and after proper mathematical reformulation, the conic quadratic optimization problem could be solved efficiently. Macro-stress shakedown domain can be obtained after scale-transformation of the RVE results. The bases of this stress domain are unidirectional stress in geometry space. The stress amplitude of a structure can be evaluated by this domain for determining the shakedown state in a simple and practical manner. Further, changes in the boundary condition of RVE do not affect the limit and elastic analysis. Finally, few numerical examples were presented for verification and illustration. This approach can be expanded to three dimensions and employed for more complex structures. |
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