《材料力学》课程教学课件（PPT讲稿）第四章 弯曲内力 Internal forces in beams（例题2）

Y例题3La-bxB2.列剪力方程和弯矩方程fx+选择坐标系RBR选取分段点wwwwwsmoAC段Q(x)0<r<a)mo(个)Rw一AmoM(x)(0<r<a)XZL(L)RB=mo-CB段aQ(x)AN三1WmoM(x)X

例题3 2.列剪力方程和弯 矩方程 AC段 l m Q x 0 ( ) = 选择坐标系 选取分段点 x l m M x 0 ( ) = (0 < x  a) (a < x  l ) CB段 l m Q x 0 ( ) = (a < x < l ) ( ) ( ) 0 l x l m M x = − − (0  x < a) A B l a b mo C RA RB y x x ( ) 0 B m R l = ( ) 0 A m R l = 

3.作剪力图和弯矩图mVAC段bmocBXAQ(x)(0<x≤a)LmoM(x)(0≤x<aRRB1AQmCB 段moXQ(x) =(a<x<l)1Mmoa/l !mo(l-x)M(x)1x(a<x≤ )mgb/l

3.作剪力图和弯矩图 AC 段 CB 段 x Q l m0 x M A B l a b C RA RB x y mo l m Q x 0 ( ) = x l m M x 0 ( ) = (0 < x  a) (0  x < a) (a < x  l ) l m Q x 0 ( ) = (a < x < l ) ( ) ( ) 0 l x l m M x = − − m a l 0 m b l 0