低速冲击下复合材料层合板非局部渐进失效分析及剩余强度研究

发布时间：2018-10-10 14:11

【摘要】：碳纤维增韧环氧树脂基复合材料具有轻质、高强、可设计性优良的特点,因此一直备受各界研究者们的青睐。近年来,渐进损伤分析方法(CDM)被广泛地应用于航空航天复合材料结构。然而,层合板的渐进损伤和连续刚度退化通常表现出高度的非线性。如何理解能量耗散后的损伤演化机理至关重要。复合材料层合板在低速冲击载荷下的失效破坏机理尤为复杂,通常伴随着应变局部化现象的产生。本文旨在针对复合材料层合板的面内损伤,引入由Ba?ant等人发展起来的非局部积分理论,通过在渐进失效模型中嵌入VUMAT子程序来解决低速冲击载荷下复合材料的局部化问题。仿真结果表明,非局部渐进失效模型能够很好地模拟复合材料试样在不同载荷条件下的失效演化和动力学响应,有效地改善了复合材料分析模型的网格敏感性问题。为进一步验证非局部渐进失效冲击模型的有效性,通过试验与有限元仿真相结合的方法,围绕民机复合材料结构冲击后剩余压缩、剩余剪切强度问题展开了研究。首先,针对T700/QY8911和T700/3234复合材料层合板的在低速冲击下的损伤演化及冲击响应进行非局部有限元模拟,将改进的Hashin准则、双线性及指数型损伤演化规律引入子程序中,验证了非局部算法在解决冲击损伤模拟问题中的准确性。然后,通过ABAQUS重启动分析,将冲击损伤以预定义场(形式赋予复合材料无损结构,分别完成了低速冲击-压缩/剪切模拟的全过程,仿真结果与试验吻合良好,大大提高了剩余强度模型的分析精度。最后,研究了引入冲击损伤后的复合材料梁腹板结构在剪切载荷下的失效机理和承载特性,发现在子层屈曲和纤维断裂的共同作用下,试验件最终失去承载能力,发生沿45?方向的失效破坏。结合非局部渐进失效模拟,完成了对复合材料梁腹板结构损伤容限的初步评估。
[Abstract]:Carbon fiber toughened epoxy matrix composites have been favored by researchers for their advantages of light weight, high strength and good designability. In recent years, the progressive damage analysis method (CDM) has been widely used in aerospace composite structures. However, progressive damage and continuous stiffness degradation of laminated plates usually show high nonlinearity. How to understand the mechanism of damage evolution after energy dissipation is very important. The failure mechanism of composite laminated plates under low speed impact loads is particularly complicated and usually accompanied by strain localization. Aiming at the in-plane damage of composite laminates, the nonlocal integral theory developed by Ba?ant et al is introduced to solve the localization problem of composites under low speed impact by embedding VUMAT subroutine in the progressive failure model. The simulation results show that the nonlocal progressive failure model can well simulate the failure evolution and dynamic response of composite specimens under different loading conditions and effectively improve the mesh sensitivity of composite analysis model. In order to further verify the effectiveness of the non-local progressive failure impact model, the residual compression and residual shear strength of civil aircraft composite structures after impact were studied by means of the combination of test and finite element simulation. Firstly, the damage evolution and impact response of T700/QY8911 and T700 / 3234 composite laminates under low speed impact are simulated by non-local finite element method. The improved Hashin criterion, bilinear and exponential damage evolution rules are introduced into the subroutine. The accuracy of the nonlocal algorithm in solving the impact damage simulation problem is verified. Then, through the ABAQUS restarting analysis, the impact damage is predefined in the form of the composite structure, and the whole process of the low-speed impact-compression / shear simulation is completed, respectively. The simulation results are in good agreement with the test results. The precision of residual strength model is greatly improved. Finally, the failure mechanism and load-bearing characteristics of composite beam web structure with impact damage under shear load are studied. It is found that under the joint action of sub-layer buckling and fiber fracture, the ultimate bearing capacity of the specimen is lost and the bearing capacity is 45? Directional failure. Combined with nonlocal progressive failure simulation, the damage tolerance of composite beam web structure was evaluated.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB33

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