Workability of 1045 spheroidized steel under superimposed hydrostatic pressure

Workability tests were performed on spheroidized {dy1045} steel to investigate the variation of forming limits due to the suppression of void growth under superimposed hydrostatic pressure. Results showed that increasing pressure enhances formability, as expressed by the increasing intercept and decreasing slope of the forming-limit line. A continuum mechanical model based on the growth and coalescence of voids under externally applied pressure is proposed that ex-plains the experimental results.     

壁厚对称波动圆环在静水压力作用下的临界外压

为了进行不均匀壁厚圆环和圆管的临界外压计算,从研究壁厚关于2个正交轴对称且波动变化的圆环在均匀静水压力作用下的平面内稳定性入手,采用傅里叶级数逼近圆环屈曲的变系数常微分方程的解,导出圆环屈曲的特征方程,分别求得圆环对称屈曲和反对称屈曲的临界外压系数.用最小相对误差拟合法得到了精度较高的临界外压系数拟合公式,其最大相对误差仅为±0.68%.分析表明,壁厚不均匀度越大,临界外压越小.采用平面应变假设,推广得到超长变壁厚圆管在均匀静水压力作用下的临界外压计算公式,并应用于某煤矿工程中超长圆钢管的局部稳定性计算,算例中当壁厚在公称壁厚和最小允许壁厚之间波动变化时,临界外压降低18.21%.