复合材料桨叶结构损伤演化模型

与金属材料桨叶相比,复合材料桨叶因具有更加优良的抗疲劳性能而被广泛应用到直升机旋翼上。但由于复合材料破坏机理复杂,疲劳性能分散,影响因素众多,导致复合材料桨叶疲劳现象尚处于研究探索之中,在复合材料的微观失效机制与宏观结构的力学性能之间仍然缺少一座桥。鉴于此,文章利用典型复合材料试样的拉伸疲劳实验数据,建立了基体裂纹、纤维断裂和界面脱胶等损伤变量累积模型,从断裂能的角度出发构建了基体裂纹密度、纤维断裂面积与复合材料属性之间的函数关系,分析了基体裂纹密度、纤维断裂面积等损伤变量对复合材料工程性能参数的影响。利用复合材料宏观力学理论,研究了各物理损伤变量对桨叶刚度特性的影响,采用连续损伤变量的状态方程建立了复合材料桨叶的损伤演化模型,这种以有理多项式为状态转移函数微分模型能很好地体现复合材料桨叶在疲劳初期和疲劳末期刚度快速损伤的现象。

Structural Damage Accumulation Model of Composite Rotor Blade

Compared to metal material blades, composite blades are widely used on helicopter rotors because of their supe?rior fatigue resistance. However, due to the complex failure mechanism of the composite material, the fatigue performanceis dispersed, and the influenc factors are numerous, the fatigue phenomenon of the composite blade is still under researchand exploration. There is still a missing bridge between the microscopic failure mechanism of the composite material andthe mechanical properties of the macrostructure. In view of this, the cumulative model of damage of matrix, fiber fractureand interfacial debonding was established based on the tensile fatigue experimental data of typical composite samples.From the point of view of fracture energy, the relationship between matrix crack density, fiber fracture area and compositeproperties was established. The effects of damage variables such as matrix crack density and fiber fracture area on the per?formance parameters of composite engineering were analyzed. Based on the phenomenological theory, the influence ofphysical damage variables on the stiffness characteristics of the blade was studied. The damage evolution model of compos?ite blade was formulated by using the state equation of continuous damage variable. This differential model with rationalpolynomials as the state transfer function can well reflect the rapid damage of the composite blade at the initial stage of fa?tigue and the end fatigue.