34.4 Rotation of Crystal dur ing Slip .I. The cause of rotation Due to constraints, or boundary conditions, imposed on the crystal The rule of rotation 1)axis of rotation R L=+(·n)b R‖L×团b×l
§4.4 Rotation of Crystal during Slip ◆ Ⅰ.The cause of rotation: Due to constraints, or boundary conditions, imposed on the crystal. ◆ Ⅱ.The rule of rotation : 1) axis of rotation ∥ ∥ R R L l b l L l l n b = + ( )
2)During slip, the S.D. tends to approach to loading direction in tension During slip, the S P. tends to approach to compression plane in compression
2) During slip, the S.D. tends to approach to loading direction in tension. During slip, the S.P. tends to approach to compression plane in compression. F F F F F F F F
Slip band (1000 atoms) Slip line(100 atoms) Distance between slip bands ( (b)
ll. The consequence of rotation 1. Change in length of the specimen ① n tension L=1+y(l·n)b L=I1+2y cos A cos o+r2 cos2 o L Xb sin Aon cos sin n ② In compression A=a-y(a·b)n
◆ Ⅲ.The consequence of rotation : 1. Change in length of the specimen 2 2 L = l 1+ 2 cos cos + cos ① In tension L l l n b = + ( ) cos cos sin sin 0 0 l L b n ② In compression A a a b n = − ( )
2. Change in orientation (1 Orientation change and multislip (2) Geometrical softening in tension Schmid's law [=o coS/ cos at the onset of slip: t=tc=const =0, coS n, cOS Fcosn F cos/ cOS COS y个→4→a√cos COS
② Geometrical softening in tension Schmid’s law at the onset of slip: = cos cos = = const. C y o o = cos cos o o o o A F A F cos cos ) cos ( cos = = o C cos cos = 2. Change in orientation ① Orientation change and multislip