Fatigue life prediction and experiment research for composite laminates with circular hole

Based on the fatigue prediction model of exponential function and Whitney-Nuismer(WN) criterion of static strength for the composite material laminate with a circular hole, the stress correct factor (β) was put forward and a new fatigue prediction model for composite material laminate was set up. T300/KH304, which is recently studied and is a high capability composite material, was used as the raw material. In order to gain the factor β, the fatigue experiments of the laminates with holes in different diameters and the same ratio of width to diameter were conducted. The fatigue analysis and tests of the laminates with a hole 5 mm in diameter are carried out at different stress levels, and the results meet the engineering requirement. The simple, prompt and practical method is provided for the prediction of S-N curve of composite laminate with a circular hole.     

航空发动机复合材料机匣在轴向压力和内压耦合作用下屈曲特性的有限元分析

复合材料是60年代出现的一种性能优异的新型材料,目前在航空航天结构领域里已得到了一些应用.本文利用线性板壳理论和线性屈曲模型,对航空发动机树脂基复合材料外涵道机匣构件的特点进行结构有限元建模和在轴向和径向载荷单独和耦合作用下屈曲特性进行有限元分析,可供航空发动机的复合材料机匣的结构设计参考.     

带孔复合材料层合板疲劳理论研究

基于复合材料层合板静强度的"平均应力准则"和经典的指数函数疲劳预测理论以及所提出应力修正因子β,建立了一种带孔的复合材料层合板疲劳预测模型.针对复合材料T300/KH304进行了带孔层合板在不同应力水平下的疲劳试验研究及模型验证,模型预测结果满足工程要求,为含圆孔层合板S-N曲线的预测提供了简单、快捷、实用的方法.     

Pulse electrical arc stimulator based on single-electrode for active exercise in tail-suspension rat

To make rat do active exercise to counteract bone loss in the rat tail-suspension model, a pulse electrical stimulator based on single-electrode with a low-current and a high-voltage was designed. The stimulator was controlled by SCM (single chip micyoco) that could accurately control the stimulation duration and the interval between stimulations, and cease the operation after the recorded number of stimulation had reached the value set by the program. With the help of posture estimation part, the device would operate intelligently by determining whether to stimulate or not, depending on the posture of rat’s limb. Software was developed to make operator control the stimulator using computer, save the experiment data and print the report. In practical experiment, the voltaic arc is generated by the stimulator, and impacted on the rat’s thenar. This induced pain to the rat and the rat would actively contract its hindlimb to evade the pain, so active exercise was carried out. The tail-suspension rats were trained twice every day for 14 d. At the 0 and 14th day, bone mineral density of rat femurs was determined by dual energy X-ray absorptiometry (DXA). The results show that the active exercise stimulated by the pulse electrical arc stimulator can attenuate weightlessness-induced bone loss, and this device is a convenient steady performance electrical stimulator that can surely induce rat’s hindlimb to do active exercise.     

轴向压力和端部转矩载荷联合作用下机匣结构稳定性的数值分析

以某航空发动机复合材料外涵道机匣构件进行结构有限元建模与线性屈曲特性的有限元分析。联接机匣的金属夹层板可起到提高机匣屈曲临界载荷的作用。利用圆柱壳体耦合载荷的研究成果,分析机匣受轴向压力和端部扭矩单独及组合作用下的屈曲行为规律,进而为航空发动机的结构设计提供参考依据,但要求得精确解还需通过实验进行适当的修正。