任意截面的任意点处，正应力<img src="https://static.zxtiku.com/wangke/imgs/topic/91003dd7490d87c6da55c2aab6767490.png"/>与切应力<img src="https://static.zxtiku.com/wangke/imgs/topic/176e75601b7b308145c6a93c9a064dfc.png"/>的夹角<img src="https://static.zxtiku.com/wangke/imgs/topic/1f8bfc1dc6e2ada565bcd328d14720a6.png"/>