热声载荷下C/SiC薄壁层合板结构动力学响应计算与寿命分析

Dynamic Response Calculation and Life analysis of C/SiC Composite Laminates under Thermoacoustic load

高超音速飞行器薄壁结构在工作环境下承受着复杂的高温强噪声载荷,高温会使材料性能发生变化,导致局部区域出现热声疲劳破坏,影响结构的耐久性和完整性。针对此类问题,基于薄壁结构大挠度非线性振动理论,构建热声载荷下四边固支C/SiC薄壁层合板结构的数值仿真模型,并对其进行了动力学响应计算,研究了不同热声载荷组合下的振动响应规律,并采用线性累计损伤理论对结构进行疲劳寿命的预估和分析。结果表明,热声载荷对碳/碳化硅薄壁层合板的非线性响应影响不同,热载荷通过改变结构基频来影响结构非线性响应。四边固支C/SiC薄壁层合板在热声载荷作用下表现出非线性随机振动特性,并且呈现在平衡位置随机振动、随机跳变等多种运动状态,跳变运动给结构造成更大的的损伤更大。

The thin-wall structure of hypersonic aircraft is subjected to complex high temperature and strong noise loads in the working environment.High temperature will change the material properties,leading to thermoacoustic fatigue damage in local areas,and affecting the durability and integrity of the aircraft structure.Based on the nonlinear vibration theory of thin-walled structures with large deflection,a numerical simulation model of thin-walled structures with four sides and fixed support C/SiC was constructed under thermoacoustic load,and the dynamic response of the structure was calculated.The vibration response of the structure under different temperature and pressure levels was studied,and the fatigue life of the structure was estimated and analyzed by the rain-flow counting method.The results show that the thermal load and the acoustic load affect the nonlinear characteristics of the structure in different ways,and the thermal load affects the nonlinear characteristics of the structure by changing the fundamental frequency.The four sides fixed C/SiC thin-walled laminates show a variety of motion states under the thermoacoustic load,showing nonlinear random vibration characteristics.The more severe the jumping motion,the greater the damage and the lower the fatigue life reduction.