阶梯形修理复合材料层合板拉伸性能研究

为获得不同参数对阶梯形修理结构拉伸力学性能的影响,本文开展了试验研究.针对铺层数目为8层的复合材料层合板,分别研究了阶梯数目为2个、4个和8个的无附加层的情况.另外针对4个阶梯的情况,研究了附加层数目的影响.作为对比,对相同修理区大小情况下的斜切形挖补修理结构也进行了测试.结果显示,对阶梯形修理结构,拉伸强度随阶梯数目的增加而增加,当阶梯数目由2个增加到8个时,修理接头的强度恢复率由36%增加到67%.通过引入附加层能够有效的提高修理结构的强度,但随着附加层的引入以及附加层数目的增加,修理结构强度的分散性变大.阶梯形修理和斜切形挖补修理的对比显示,相同修理面积的情况下,由于斜切形挖补修理能够提供更加均匀的胶膜应力分布,斜切形挖补的修理效率要高于阶梯形修理,相比4个阶梯的阶梯形修理,斜切形挖补修理强度能够提高25%.最后,根据修理接头表面各点的应力/应变分布规律,获得了拉伸载荷作用下修理接头的失效机理和失效过程.

Tensile performance of stepped-lap repair of composite laminates

To obtain the effect of different parameters on the tensile performance of stepped-lap repaired composite laminates, the repaired specimens were investigated experimentally. In terms of the laminates with 8 plies, stepped-lap repaired specimens with 2, 4 and 8 steps were tested, respectively. In addition, the stepped-lap joint with 4 steps was studied with different number of external plies. As a comparison, a tapered scarf repair with the same bonding area was also tested. Results showed that the tensile strength of stepped-lap repairs increased with increasing the number of steps. When the number of steps increased from 2 to 8, the strength recovery rate of the repaired joint increased from 36% to 67%. The introduction of external plies could also improve the efficiency of repairs. However, the dispersion of the repair strength increased with the increase of external plies. As the stress distribution in the adhesive film is more uniform for the tapered scarf joint, its repair strength is higher. Compared the stepped-lap repaired joint with the tapered scarf joint with the same bonding area, the repair efficiency of the latter is higher. Take the 4 stepped-lap repaired joint for example, its repair strength is increased by 25% compared with that of the tapered scarf joint. Finally, according to the stress/strain distribution on the surface of the repaired joints, the failure mechanism and failure process of the repaired joints under tensile load were obtained.