复合材料抗冲击性能和结构压缩设计许用值

 从复合材料结构压缩设计许用值的概念和复合材料的冲击后压缩强度性能出发，讨论按NASA标准得到的CAI值与它们的关系，指出传统的CAI值不能充分反映复合材料体系的抗冲击性能，且与结构压缩设计许用值无任何联系。在对复合材料结构完整性要求和作者的试验研究，和对国外文献总结的基础上，提出复合材料抗冲击性能应包括损伤阻抗和损伤容限两方面。大量的试验数据证实复合材料层压板抗冲击性能存在拐点现象，在对拐点附近复合材料层压板的破坏机理研究基础上，建议用拐点附近的性能建立复合材料层压板抗冲击性能的评定体系，即可以用表面层在冲击下保持其完整性的最大能力(最大接触力)来表征复合材料体系的损伤阻抗(韧性)；用出现拐点后基本不变的压缩强度(破坏应变)门槛值来表征复合材料体系的损伤容限。

Behaviors of Composite Materials to Withstand Impact and Structural Compressive Design Allowableness

In this paper the relationship between CAI obtained by NASA test standard and compressive design allowableness of composite structure are discussed based on the concept of structural design allowableness and the compressive-after-impact behaviors of composites, and it is pointed out that the traditional CAI values could not reflect the behaviors of composite materials to withstand impact adequately and no relationship between CAI values and structural compressive design allowableness existed. Based on the integrity requirements of composite structures, experimental study by authors and the conclusions from available references, it is pointed out that the behaviors of composite materials to withstand impact should include both the damage resistance and the damage tolerance. Large numbers of test data verify that the knee point phenomenon of composite material to withstand impact existed. Based on failure mechanisms, it is proposed that the behavior evaluation system of composite system to withstand impact is based on the properties at the knee point, that is, the maximum capability to keep integrity of the front plies (the maximum allowable contact force) characterizing the damage resistance and the threshold of dent depth(or impact energy)-compressive strength(or failure strain) curves characterizing the damage tolerance.