Crashworthiness of double-cell conical tubes with different cross sections subjected to dynamic axial and oblique loads

Thin-walled tubes are increasingly used in automobile industries to improve structural safety.The present work deals with the collapse behavior of double-cell conical tubes subjected to dynamic axial and oblique loads.Crashworthiness of these tubes having different sections(e.g.,circular,square,hexagonal,octagonal,decagonal)was numerically investigated by using an experimentally validated finite element model generated in LS-DYNA.Geometry of these tubes was then optimized by decreasing the cross section dimensions at the distal end while the weight remained unchanged.Octagonal conical tube was finally found to be more preferable to the others as a collision energy absorber.In addition,square and circular tubes showed diamond deformation mode,while the other tubes collapsed in concertina mode.A decision making method called TOPSIS was finally implemented on the numerical results to select the most efficient energy absorber.

Miner线性累积损伤理论在滚筒洗衣机轴承寿命计算中的应用

以预测滚筒洗衣机的轴承使用寿命为目标,根据滚筒洗衣机的工作原理,对滚筒洗衣机受力模型进行简化。基于此阐述滚筒洗衣机轴承寿命计算的方法,将轴承基本寿命计算分为三个部分进行:a)基于简化的受力模型,推导出轴承承受力表达式;b)结合ISO 281《滚动轴承额定动载荷及额定寿命》中轴承基本寿命计算公式,计算洗衣机不同工况下的循环载荷;c)引入Miner线性累积损伤理论,探讨循环载荷与总当量载荷的关系。根据洗衣机的变幅循环载荷受力特点,将ISO 281与Miner线性累积损伤理论结合应用于滚筒洗衣机轴承寿命计算,推导出平均当量动载荷表达式,回答了不同工况下的循环载荷与总当量动载荷之间的关系。