7A04铝合金厚壁筒扩口成形工艺研究

基于刚塑性有限元方法的数值模拟,对7A04铝合金厚壁筒扩口成形过程进行了分析,比较了不同温度、不同摩擦条件下扩口的应变分布和成形力变化。在此基础上进行了相应的工艺实验研究。结果表明,模拟结果和实验结果基本一致;在制定的工艺参数下,实现了铝合金厚壁筒的大比率扩口,为铝合金厚壁筒扩口成形技术的应用提供了依据。

Influence of lunar regolith compressibility on sampling performance of thick wall spiral drills

A 2 m class robotic drill was sent to the Moon and successfully collected and returned regolith samples in late 2020 by China.It was a typical thick wall spiral drill(TWSD)with a hollow auger containing a complex coring system to retain subsurface regolith samples.Before the robotic drill was launched,a series of laboratory tests were carried out to investigate and predict the possible drilling loads it may encounter in the lunar environment.This work presents how the sampling performance of the TWSD is affected by the regolith compressibility.Experiments and analysis during the drilling and sampling process in a simulated lunar regolith environment were conducted.The compressibility of a typical lunar regolith simulant(LRS)was measured through unidirectional compression tests to study the relationship between its inner regolith stress and bulk density.A theoretical model was established to elucidate the cutting discharge behavior by auger flights based on the aforementioned relationship.Experiments were conducted with the LRS,and the results show that the sampling performance is greatly affected by the flux of the drilled cuttings into the spiral flight channels.This work helped in scheduling reasonable drilling parameters to promote the sampling performance of the robotic drill in the Chinese Chang’E 5 mission.

铝制易拉罐罐身成形有限元模拟

以铝制易拉罐罐身成形过程为研究对象,在考虑材料三向应力的基础上,采用各向同性体单元进行变形体的离散处理,利用Ls-dyna模拟计算平台建立了相应的全工序有限元模型,对成形过程中铝制易拉罐罐身的壁厚变化进行了模拟分析,并基于罐身成形试验壁厚分布结果进行了模型模拟精度的验证。同时,基于此三向应力模型研究了模具表面摩擦系数对铝制易拉罐罐身成形的影响规律。结果表明:基于该模型模拟得到的罐身壁厚分布规律与实际测量结果相符;较高的冲头摩擦系数以及较低的减薄拉深模具摩擦系数有利于减少罐身成形开裂的发生,从而提高易拉罐罐身的生产效率。