复合材料开孔层板压缩渐进损伤试验

为研究碳纤维增强树脂基复合材料开孔层板在压缩加载过程中的损伤起始、演化方式和损伤特点,采用微距拍摄、逐级加载超声C扫描、X光扫描和扫描电子显微镜观测4种观测手段对国产CCF300/5228A45/0/-45/90]4s、452/02/-452/902]2s、454/04/-454/904]s3种铺层方式的开孔层板进行了压缩试验研究。对压缩载荷作用下开孔层板的损伤起始和损伤演化进行了观察和对比。对试验中观测到的纤维微屈曲、纤维挤出、孔边开裂和分层扩展等现象之间的关系进行了分析和说明。试验结果表明:压缩载荷下45°和90°铺层相邻位置为层板易分层位置,含45°和90°铺层相邻位置的开孔层板渐进损伤过程较为明显:开孔层板在压缩载荷下较早出现损伤,损伤的起始和演化缓解了孔边应力集中,促使压缩应变能在孔边逐步释放,推迟开孔层板压缩破坏的发生,提高层板压缩承载能力。研究结果可为材料结构损伤容限设计提供依据。

Test on progressive damage of open-hole composite laminates under compression load

In order to study damage initiation, evolution ways and damage characteristic of carbon fiber reinforced resin matrix composites open-hole laminates under compression load, compressive tests of open-hole domestic CCF300/5228A laminates of three kinds of layup 45/0/-45/90]_4s, 45₂/0₂/-45₂/90₂]_2s, 45₄/0₄/-45₄/90₄]_s were investigated based on four methods: macro photography, ultrasonic C-scan together with multi-stage loading, X-scan and scanning electron microscope. The damage initiation and damage propagation of open-hole laminates under compression load were observed and compared. The fiber micro-buckling, fiber extrusion, cracks and delamination on hole edge during tests were analyzed and explained. The test results show that delamination occurs easily at positions between 45° and 90° layups of laminates under compression load. Phenomenon of progressive damage is obvious at the edge of the hole in laminates within positions between 45° and 90° layups. The relief of stress concentration and strain energy on the hole edge are caused by the early initiation and propagation of damage. The relief delays the final failure and increases compressive bearing capacity of the laminates. The results can provide a guidance for the damage tolerance design of composite structures.