复合材料涡轮轴结构损伤演化及失效机理

Damage evolution and failure mechanism of composite turbine shaft structure

针对连续纤维增强复合材料涡轮轴结构损伤演化及失效机理分析,基于宏-细观力学跨尺度分析方法,建立了与轴结构试验件尺寸相符合的有限元仿真计算模型及细观力学代表体积元(RVE)模型,预测轴结构的损伤演化并分析其失效机理。反向扭矩下,[45]_(6)轴结构的损伤始于界面开裂,裂纹向两侧钛合金扩展,钛合金的剪切变形最终带动纤维的断裂;正向扭矩下,[45]_(10)轴结构的损伤始于基体损伤,断口两侧钛合金相互挤压摩擦,最终将纤维剪断。开展复合材料失效模式验证试验,通过声发射及扫描电镜技术,实现对失效过程中不同失效模式的判别。将仿真结果与试验结果进行对比验证,验证了模型和方法的有效性。模拟涡轮轴结构在扭转载荷下的损伤演化过程及失效机理,预测失效强度。结果表明:0°和90°铺层时扭转强度最低,45°铺层时扭转强度最高,提高近3倍。本文研究提出的预测模型及分析结论为纤维增强复合材料的设计和应用提供依据。

For continuous fiber reinforced composites turbo-shaft structural damage evolution and failure mechanism analysis,based on the macro-mechanics and meso-mechanics analysis method of crossscale,a finite element simulation model with the same size of the shaft structure verification model and a micro-mechanics representative volume element(RVE)model was established.The damage evolution of shaft structure was predicted and its failure mechanism was analyzed.Under reverse torque,the damage of[45]_(6) shaft structure structure began with interface cracking,the cracks were extended to both sides of titanium alloy,and the shear deformation of titanium alloy finally drove the fiber fracture.Under forward torque,the damage of[45]_(10) shaft structure began with matrix damage,titanium alloys on both sides of the fracture were pressed against each other,and finally the fiber was cut.The failure mode verification experiment of composite shaft structure was carried out,different failure modes in the failure process were identified by acoustic emission and scanning electron microscopy techniques.The simulation results were compared with experiment results to verify the validity of the model and method.The damage evolution process and failure mechanism of the turbo-shaft structure under torsional load were simulated and the failure strength was predicted.The damage evolution process and failure mechanism of turbo-shaft structure under torsional load were simulated and the failure strength was predicted.The results showed that the torsional strength was the lowest when the layer was laid at 0°and 90°,and the highest when the layer was laid at 45°,which increased nearly three times.The prediction model and analysis conclusions could provide a basis for the design and application of fiber reinforced composites.