纤维增强复合材料涡轮轴结构疲劳寿命预测

研究了连续纤维增强复合材料低压涡轮轴结构在给定低循环载荷作用下的疲劳寿命估算方法.考虑连续纤维增强复合材料结构特性，研究了基于局部应力应变法的低周疲劳寿命预测方法，并对预测方法的有效性进行了验证.基于此方法，计算了某型航空发动机低压涡轮轴的最大应力、应变和疲劳寿命.结果表明:在0°~90°范围内，45°铺层角度的复合材料层疲劳寿命值最大；当金属厚度不变，外层金属和首层复合材料层的疲劳寿命随复合材料厚度增加而增大；当轴结构壁厚保持6mm不变，减小复合材料层的厚度，同时相应增大最内层或最外层金属包套的厚度，其结构疲劳寿命都随着复材层的厚度减小而减小;外层金属包套的寿命则远大于首层复合材料的疲劳寿命. 

Fatigue life prediction of fiber reinforced composites turbine shaft structure

The method of estimating the fatigue life of the low pressure turbine shaft structure made of continuous fiber reinforced composite material under given low cycle loading was studied.Structural characteristics of continuous fiber reinforced composites were considered,low cycle fatigue life prediction method based on the local stress strain theory was studied,and the efficiency of the method was proved.A certain type of low pressure turbine shaft of the engine was selected for reference,the maximum stress,strain and fatigue life were calculated with the method.Result showed that,the fatigue life value of the 45° angle of composites layer was the biggest within the scope of the 0°-90°;when the thickness of the metal remained unchanged,the composite material fatigue life of outer metal and the first layer increased with the increasing thickness of the composites;when the shaft wall thickness was 6 mm,if reducing the thickness of the composites layer,and increasing the inner or the outer metal coating thickness,the structure fatigue life decreased as composites layer thickness decreased;the life of the outer metal coating was longer than the fatigue life of the first layer's composite materials.