编织复合材料机身隔框的冲击动力学特性

为提高飞行器的适坠性能,对二维三轴编织复合材料机身隔框的冲击动力学特性进行研究。基于连续介质损伤力学建立了机身隔框在冲击载荷作用下的有限元模型。该模型根据不可逆热力学理论并结合Weibull分布建立损伤扩张准则,采用Hashin失效准则确定损伤阈值函数。在迭代过程中,剪应力与正应力相互耦合,且分别考虑材料在纵向和横向的损伤破坏。在此基础上研究了材料参数变化对机身隔框冲击动力学性能的影响,并对各种情况下的瞬态动力学特征和能量吸收特性进行对比分析。数值结果表明该有限元模型能够准确求解编织复合材料机身隔框的非线性瞬态动力学问题,载荷峰值和吸收的能量分别与试验结果相差1.5%和4.7%,且纵向的弹性模量和压缩强度等材料参数对机身隔框的冲击动力学响应影响较大。

Impact dynamic characteristics of braided composite fuselage frame

To improve the crashworthiness of aircraft,the impact dynamic characteristics of 2D triaxial braided composite fuselage frame were investigated.Based on continuum damage mechanics,a finite element model of the fuselage frame under impact load was developed where irreversible thermodynamic theory combined with Weibull distribution and Hashin failure criterion were utilized to establish the damage growth law and determine damage threshold function,respectively.Shear stress was coupled with normal stress and the damage modes in both longitudinal and transverse direction of the material were considered independently in the iteration procedure.On this basis,the effects of varying material parameters on the impact dynamic performances of the frame were analyzed,and the transient response characteristics and energy absorption behaviors were compared further.Numerical results show that the finite element model is able to deal with this nonlinear transient dynamical problem accurately.The deviation between the simulation and the test on peak load is 1.5 ％,while absorbed energy is 4.7％.Besides,the longitudinal material parameters such as Young's modulus and compression strength have a significant influence on the dynamic response of the fuselage frame.