碳化硅纤维增强碳化硅基复合材料的疲劳行为模拟分析

Simulation analysis of fatigue behavior of SiC fiber reinforced SiC matrix composites

连续碳化硅纤维增强碳化硅基复合材料(SiC_(f)/SiC)因其轻质、耐高温和高损伤容限的优点而成为下一代航空发动机的重要热结构材料。然而,疲劳实验周期长、成本高的缺点严重制约了对复杂细观结构SiC_(f)/SiC的深入理解及其工程应用。为充分发挥SiC_(f)/SiC的优势与可调性,实现对结构载荷响应预测并进行优化设计,本文采用疲劳迟滞模型和渐进损伤理论分别对单向、正交和二维编织SiC_(f)/SiC的疲劳寿命曲线进行了分析。通过对界面剪应力(±20%)、纤维强度(±5%)、纤维威布尔模量(±1%)和纤维体积分数(±5%)进行偏值处理实现了对SiC_(f)/SiC疲劳寿命的敏感性评价,得到的疲劳寿命曲线上下限能够包络主要实验结果。根据上述分析结果,验证了以损伤参数控制危险估计和保守估计的疲劳寿命曲线拟合方法,并以SiC_(f)/SiC涡轮叶片模拟结构为例现实了该方法用于实际工程评价分析的可行性。

The continuous carbon fiber reinforced silicon carbide matrix composite(SiC_(f)/SiC)has become an important thermal structural material for the next generation of aerospace engines due to its advantages of lightweight,high-temperature resistance,and high damage tolerance.However,the long fatigue test cycles and high costs severely limit the in-depth understanding and engineering applications of complex microstructures of SiC_(f)/SiC.To fully exploit the advantages and tunability of SiC_(f)/SiC,and to achieve the prediction of structural load response and optimization design,this study analyzed the fatigue life curves of unidirectional,orthogonal,and twodimensional braiding SiCf/SiC using fatigue hysteresis models and progressive damage theory.The sensitivity evaluations of SiC_(f)/SiC fatigue life were achieved by adjusting parameters such as interfacial shear stress(±20%),fiber strength(±5%),fiber Weibull modulus(±1%),and fiber volume fraction(±5%)through bias processing.The resulting upper and lower bounds of the fatigue life curves enveloped the primary experimental results.Based on the above analysis,a method for fitting fatigue life curves was verified,controlling hazard estimation and conser vative estimation with damage parameters.The practicality of this method for practical engineering evaluation was demonstrated with simulated structures of SiC_(f)/SiC turbine blades.