图5-7-4所示正方形截面杆AB,力F作用在xOy平面内,与x轴夹角α。杆距离B端为a的横截面上最大正应力在α=45°时的值是α=0时值的( )。[2014年真题]
图5-7-4
A、<img width="40" height="33" src="http://admintk.100xuexi.com/UpLoadImage/2013-05-07/0bd414cf-77e2-4037-ab22-5e6dcf38c1f6.png" />
B、<img width="45" height="20" src="http://admintk.100xuexi.com/UpLoadImage/2013-05-07/2ba72c8c-e3ea-4984-af9f-5f85e98282b2.png" />
C、<img width="42" height="34" src="http://admintk.100xuexi.com/UpLoadImage/2013-05-07/017779fc-0457-41ca-8d32-94d91cf75c67.png" />
D、<img width="29" height="20" src="http://admintk.100xuexi.com/UpLoadImage/2013-05-07/ea277758-bdaa-4f43-a0b0-4708b1a811a4.png" />
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