缝合复合材料低速冲击损伤研究

通过三维动力学有限元法,采用空间杆单元来描述缝线,结合试验系统地研究了缝合复合材料的低速冲击损伤问题。采用修正的赫兹接触定律计算冲击接触力,NewMark直接积分法求解运动方程,求解冲击过程中的应力应变;在Chang和Hou等的分层扩展准则基础上,提出一修正的分层扩展准则并考虑纤维断裂,建立了分析低速冲击损伤面积的方法;对相同铺层的缝合与未缝合复合材料层板进行了低速冲击试验。分析结果与实验结果具有良好的一致性,证明本文中提出的修正的分层扩展准则是正确的。计算及试验结果均表明,在相同冲击能量作用下,缝合使冲击损伤面积明显减小。 

STUDIES ON LOW-VELOCITY IMPACT DAMAGE OF STITCHED COMPOSITES

A 3D dynamic finite element method with stitching threads is described by the space bar element and combined with experiment work to study the damages of the stitched composites induced by the low-velocity impact in this paper. Impact induced contact forces by modified Hertz contact law are obtained, the dynamic equations are solved with NewMark direct integral scheme, and strain and stress during impact are obtained. A modified delamination criterion considering fibre failure is proposed based on that of Chang and Hou, and the method to analyse the impact induced failure area is developed. Impact tests on the stitched and unstitched composite laminates with the same ply sequence are performed. Good agreement is found between experiment and finite element computing resuits, and the results indicate that stitching greatly reduces the extent of the impact damage area at the same impact energy level.