This study investigated the fatigue fracture of bilateral drive drum shafts in casting bridge cranes including its fracture morphology and factors, such as materials, manufacturing processes, and loads. Seven conditions were designed to test the effects of changes in the speed and torque of the drum shafts during startup, commissioning and braking under different loads. A dynamic model was developed for the structure and control system of the hoisting mechanism. Changes in the speed and torque of the motor and drum shafts were simulated under common operating conditions such as speed and load changes of the motor, control asynchrony and single-motor towing. The results showed that asynchronous motor starting and braking, motor dragging and other behaviors led the left and right drum shafts undergo oscillated torque with a value reached 2 × 10⁵ N∙m in a period of approximately 13 s, and a residual torque about 3 × 10⁴ N∙m was retained after braking. The torques on the drum shafts changed suddenly during the processes of starting, shifting and braking. Dynamic loading was the root cause of fatigue fracture of the drum shafts.

中文翻译：

---

铸造桥式起重机滚筒轴断裂失效的试验研究、模拟与分析

本研究调查了铸造桥式起重机双边驱动滚筒轴的疲劳断裂，包括其断裂形态和材料、制造工艺和载荷等因素。设计了七个条件来测试在不同负载下启动、调试和制动过程中滚筒轴的速度和扭矩变化的影响。建立了起升机构结构和控制系统的动力学模型。模拟了电机转速和负载变化、控制异步和单电机牵引等常见工况下电机和滚筒轴的转速和扭矩变化。结果表明，异步电机启动和制动、电机拖动等行为导致左右滚筒轴发生振荡扭矩，值达到2×10在大约 13 s 的时间内产生^{5 N∙m，制动后保持约 3 × 10 4} N∙m 的残余扭矩。在启动、换档和制动过程中，滚筒轴上的扭矩会发生突变。动态载荷是滚筒轴疲劳断裂的根本原因。