The bridge crane demonstrates dynamics behavior that the flexible mode has a natural frequency depending on the string length. In this project, a portable bridge crane is designed and made to demonstrate this dynamical phenomena by changing speed and string length. The portable bridge crane requires a light mass and a small size. At the same time, because it needs to be observed in a two-dimensional plane, the trolley must be able to move horizontally on a bridge with tracks, and the speed of the trolley needs to be controlled by a speed controllable motor. The crane needs to suspend a weight of 1 kg to demonstrate the change in natural frequency. The length of the rope needs to be adjustable. In addition, in order to ensure the stability of the instrument, it is necessary to reduce the impact force of the collision when the trolley hits the ends of the rail. Therefore, a soft stop is necessary to stop the motion of the cart before the collision at the end. In this way, the stability of the structure can be guaranteed in order to avoid tipping due to collision. Our portable bridge crane will demonstrate the effect of changing the speed and the string length on the natural frequency.
Mechanical Engineering Design Project (MEMS 411)
Shen, Daniel; Mau, Man Kit; Lu, Haoxiang; and Xu, Kaijun, "MEMS 411: Portable Bridge Crane with Pulleys" (2021). Mechanical Engineering Design Project Class. 141.