Nonlinear dynamic modeling of a helicopter planetary gear train for carrier plate crack fault diagnosis

Planetary gear train plays a significant role in a helicopter operation and its health is of great importance for the flight safety of the helicopter. This paper investigates the effects of a planet carrier plate crack on the dynamic characteristics of a planetary gear train, and thus finds an effec- tive method to diagnose crack fault. A dynamic model is developed to analyze the torsional vibra- tion of a planetary gear train with a cracked planet carrier plate. The model takes into consideration nonlinear factors such as the time-varying meshing stiffness, gear backlash and viscous damping. Investigation of the deformation of the cracked carrier plate under static stress is performed in order to simulate the dynamic effects of the planet carrier crack on the angular displacement of car- rier posts. Validation shows good accuracy of the developed dynamic model in predicting dynamic characteristics of a planetary gear train. Fault features extracted from predictions of the model reveal the correspondence between vibration characteristic and the conditions （length and position） of a planet carrier crack clearly.

薄煤层铲板车轮辋开裂分析与优化

轮胎作为承载整车的关键部件,不仅可以传递驱动力和制动力,还可以吸收和缓和车辆行驶时所受的部分冲击和振动,还能保证整车有良好的乘坐舒适性和行驶平顺性。而轮辋则是安装和支撑轮胎的部件,一旦轮辋开裂,会导致轮胎漏气,致使轮胎软蹋,造成较严重的安全事故。以矿区薄煤层铲板车轮辋开裂为研究对象,采用Abaqus有限元分析软件对轮辋的应力分布情况进行分析,同时对轮辋开裂区域结构进行宏观金相实验。结果表明,轮辋焊缝中存在焊缝缺陷,使得轮辋结构承载能力降低,在外载荷作用下发生焊缝开裂,据此从工艺和结构进行优化改进,通过仿真分析及整车运行,得到优化后的结构能经受住各种恶劣工况考验,以验证改善措施的有效性。

直升机行星架疲劳裂纹扩展寿命预测

直升机行星齿轮保持架(简称行星架)是传动系统的重要部件,其可靠性对于直升机的飞行安全至关重要。行星架疲劳裂纹故障的发生、发展受多种因素影响,其故障诊断和寿命预测都有难度。为准确预测行星架疲劳裂纹寿命,研究了其裂纹故障发生、发展规律,提出了基于对数线性的方法,将裂纹扩展过程离散化处理,采用Paris公式,定量描述裂纹扩展速率,结合Miner准则,累积其疲劳损伤过程,最终得到随裂纹长度变化的行星架剩余使用寿命数值。利用有限元软件ANSYS Workbench的疲劳寿命模块对计算得到的数值结果进行了仿真对比,验证了方法的精确性和有效性。