复合材料翼盒壁板低速冲击接触力、凹坑特性及其模拟

为预测复合材料层合板的低速冲击特性,提出一种基于弹簧-质量模型的冲击分层响应模拟方法。首先根据假定的分层数量和分层面积计算分层前后的弯曲刚度与挠度变化,进而模拟出含分层过程的冲击头运动时间历程。然后,由冲击头的加速度计算接触力,并基于材料的弹-塑性接触定律计算出永久凹坑深度。随后,对共固化复合材料翼盒的壁板进行了低速冲击实验,冲击点分为3种类型:2个梁间蒙皮的中点位置、蒙皮与翼梁T型连接的胶接区边界和梁的正上方。接着,分析对比了不同冲击点的接触力、分层阈值力和凹坑深度的特点。最后,使用所提出的模型计算第1种冲击点的接触力、永久凹坑深度和吸收能量,并分析了矩形板长宽比对薄膜刚度及接触力的影响。结果表明:模拟的接触力与实测结果吻合良好,对永久凹坑深度和吸收能量的模拟精度也较高,所提模拟方法有效;随着长宽比的减小,薄膜刚度迅速增大,从而使接触力显著增大。 

Contact force and indentation characteristics due to low velocity impact of composite wing-box panel and their simulations

In order to predict the low-velocity impact characteristics of composite laminates, a simulation method for impacting delamination response was proposed based on spring-mass model. First, the changes of flexural rigidity and deflection before and after delamination were calculated according to the presupposed delamination number and delamination area, therefore the time histories of tup motions with the delamination event was simulated. Then, contact force was calculated by the acceleration of tup, and the permanent indentation depth was calculated based on the elasto-plastic contact law of material. Whereafter, the low-velocity impact experiment was carried out on the panel of co-curing composite wing box, and the impact sites were divided into three types: the mid-point position of the skin between two spars, the boundary of the T joint bonding area of skin and spar, and the point just over the spar. After that, the characterstics of contact force, delamination threshold force and indentation depth of different impact sites were contrasted and analyzed. Finally, the contact force, permanent indentation depth and absorbed energy of impact site of the 1st type were calculated by the proposed model, as well as the influences of length-width ratio of rectangle plate on the membrane stiffness and contact force were also analyzed. The results show that the simulated contact force is well agreed with the measured result, and the accuracy of simulations for permanent indentation depth and absorbed energy are also acceptable, thus the proposed model is available. The membrane stiffness increases rapidly with the length-width ratio decreasing, thereby promotes the contact force increase significantly.