基于刚度下降的疲劳累积损伤模型的研究

复合材料在静态和动态载荷作用下的损伤是十分复杂的,对损伤的精确建模是关系到复合材料力学行为描述的关键问题.从应变等效性假设出发,通过分析和描述疲劳过程中刚度和应变的演化规律,提出能够描述材料疲劳损伤演化过程的、以应变定义的和在疲劳过程中真实地反映材料动态本构关系的损伤因子,建立考虑残余应变的刚度下降复合材料疲劳损伤模型.T300/KH-304是我国新近研制的高性能航空复合材料,应用此模型开展对其疲劳损伤行为的分析与研究.在岛津液压伺服试验机上,加载频率控制在4.1?Hz,对这种材料的层合板进行4个常幅应力水平的疲劳实验,建立了T300/KH-304复合材料的疲劳模型的数学表达,经验证模型优于经典的疲劳模型的S-N曲线拟合精度,最大的误差仅为2.4％,且能反应疲劳损伤的发展规律.

Fatigue damage accumulation model based on stiffness degradation

Damage of composite materials is very complex under static and fatigue loads. It is important for mechanical behavior to model the damage of composite materials. To simulate fatigue damage and predicate the fatigue life of composite material, a new fatigue model is given according to the strain equivalence principle and considering the deficiency of fatigue damage accumulation. T300/KH-304, which is recently studied, is a high capability composite material for aero-engine. All samples were tested in an SHIMADZ servo-hydraulic fatigue machine under computer control. The load was cycled at a frequency of approximately 4.1Hz. Samples were carried in the constant amplitude fatigue test of the composite materials under different stress levels. This damage model was set up for T300/KH-304 laminate. The result of this model prediction is closer to the test than using S-N cure. The relative error is less than 2.4%. The fatigue damage evolution law of the composites materials could also be described. This model need be studied further.