濮良贵机械设计第九版课后习题答案完整版

B截面

WB?0.1d3?0.1?503?12500mm3 ζcaB? C截面

WC?0.1d3?0.1?453?9112.5mm3 ζcaC?M'caC315.868??34.66MPa WC9112.5?10?9M'caB523.173??41.85MPa WB12500?10?9 轴的材料为45号钢正火，HBS?200,ζB?560MPa,?ζ?1??51MPa ζcaC?ζcaB??ζ?1?，故安全。