2018, 39(12): 1377-1389.
doi: 10.21656/1000-0887.380185
Abstract:
During the launching process of electromagnetic rails, the armature slides along the rails, and high-temperature friction occurs on the rail-armature interface, so the rail is liable to damages due to wear, erosion and strength loss. Thus, copper-based composite materials are used to enhance the strength and ablation resistance of the inner surface of the rail. The steel-copper composite electromagnetic rails were studied. While electrified, the armature and the rails constituted a closed loop, and a strong magnetic field formed between the rails, then the armature moved along the rails under the pushing force from the magnetic field. In this process, due to the interaction between the current and the magnetic field, a repulsive force acted between the 2 rails. At the same time, the armature was greatly heated by the strong current, and the thermal expansion of the armature brought extrusive forces on the lateral rails. According to this force condition, the composite rails were simplified as a mechanical model of double-layer beams under a uniformly distributed load and a rigid stamp force. The forces by the armature on the rail surface were solved and the stress state of the composite layers was obtained with the basic equations in the elastic half plane. Hence, the polynomial fitting of the copper-steel interfacial stress was got with the MATLAB software. The boundary conditions of the copper layer surface were determined, the local stresses of the copper layer surface were analyzed, and the relationships between the stress and the loading voltage, as well as the thickness ratios of composite layers, were acquired. The results provide a foundation for the strength design of composite launching electromagnetic rails.
