轴向冲击下薄壁圆柱壳的屈曲行为的实验研究

由于薄壁圆柱壳比厚壁圆柱壳的不均匀性更大，薄壁圆柱壳的轴向动力屈曲比厚壁复杂得多。了解轴向冲击下薄壁圆柱壳的屈曲行为，有助于进行吸能构件设计。介绍了采用落锤实验进行圆柱壳的动力屈曲行为研究中，超薄壁圆柱壳的一些特殊屈曲行为，在实验中观察到随着径厚比的增加，折屈边数有相应增加的趋势，存在过渡区。经吸能特性分析，随着圆柱壳径厚比的增加，平均压垮载荷和一个基本变形单元能量吸收量增加，有效压缩距离和一个基本变形单元的初始长度增加，但有效压缩距离与基本变形单元长度之比保持不变；在壁厚相同的条件下，能量吸收量与圆柱壳半径成正比。     

A New Damper for Tracked Vehicle Suspension

The passive suspension system of tracked vehicle is designed to get its suspension parameters based on a certain common velocity and a certain road surface roughness. Its performance optimization only exists in a certain operating mode without far-ranging adaptability. Holding the damper basic frame form and applying semi-active suspension system based on MR (magnetorheological) damper, the vehicle can keep its optimum efficiency between energy dissipation and vibration reduction in all kinds of operating modes. Theoretical analysis and experiments show that the damping performances provided by this MRF(magnetorheological fluids) vane damper are same as those provided by traditional damper, and the new damper has the better controllability and adaptability.     

Sn-Ag基无铅焊料应变率效应的研究

随着人们环保意识的增强,在世界范围内开展了对无铅焊料的研究和开发。利用分离式Hopkinson压杆实验技术研究了Sn-Ag系无铅焊料在不同应变率下的动态压缩性能。实验表明Sn-Ag系无铅焊料有的明显应变率效应:与静载荷作用下的情况相比,冲击载荷作用下的屈服和流动应力有显著的提高;与锡铅焊料相比,其动态力学性能有明显的优势。