顶角为2q的菱形结构，受沿对角线CO的力的作用。为了用虚位移原理求杆AB的内力，解除杆AB，代以内力则C点的虚位移与A，B点的虚位移的比为drC:drA:drB=__________________，内力FA=______________。http://image.zhihuishu.com/zhs/onlineexam/ueditor/201901/48062e54c3f04a17aa4e021130310f70.png
举一反三
- 机构在图示瞬时有，若A点的虚位移为drA，则B点的虚位移的大小drB=____________________，OC杆中点D的虚位移的大小drC=_________________________。http://image.zhihuishu.com/zhs/onlineexam/ueditor/201901/78a1ce1550834117b5fb6d4e762ea8d8.png
- 图示结构 AB 杆的内力为零。http://image.zhihuishu.com/zhs/onlineexam/ueditor/201906/bf5c3bb145c44afda431de3540f917cf.png
- 图示曲柄连杆机构，已知曲柄OA长L，重量不计，连杆AB长2L，重P，受矩为M的力偶和水平力Ｆ的作用，在图示位置平衡。若用虚位移原理求解，则必要的虚位移之间的关系为___________，力F的大小为_____________________。<img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201901/be06434307bd424abfc4ebfe02661f7a.png" /> A: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201901/b8e7b964d1c84aeca7b22ddef4de87a2.png" />;<img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201901/a584946cde17410c945d6611ff2113b5.png" /> B: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201901/1aaef24e28ee477ab25dae0a400bf23f.png" />;<img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201901/f3b395453e1d48bdadff2e37dfbbb626.png" /> C: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201901/be37912822f0451bb15639b7fa0589f1.png" />;<img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201901/6d1112b5c1b4446b93578138388ed79f.png" /> D: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201901/89b7bcef6b51410cb624a654747d56ee.png" />;<img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201901/0e2b78f437914a1eb8327d13185eaedf.png" />
- 如图所示桁架结构，F=140kN,图中各三角形都等腰直角三角形（边长l)。用虚位移原理求杆件CK的内力，采用虚速度法：[img=492x500]180339346508d70.png[/img] A: D点的虚位移为零 B: E点的虚位移为零 C: H点的虚位移为零 D: C点的虚位移为零
- 如图所示桁架结构，F=140kN,图中各三角形都等腰直角三角形（边长l)。用虚位移原理求杆件BD的内力，采用虚速度法:[img=492x500]18033934021319f.png[/img] A: 点C的虚位移为零 B: 点B的虚位移不为零 C: 点H的虚位移为零 D: 点D的虚位移为零