Hysteretic Internal Friction

It i s emphasized t h a t a d i s t r i b u t i o n func t ion i n both the d i s l o c a t i o n loop lengths and obstac le s t rengths must be considered t o develop a q u a n t i t a t i v e theory f o r the h y s t e r e t i c d i s s i p a t i o n o f energy. That i s when d i s l o c a t i o n surmounts an undulat ing i n t e r n a l s t ress f i e l d and t h e break-away i s r e s t r i c t e d by a r e s t o r i n g force considered t o be t h a t o f d i s l o c a t i o n 1 i n e tension. The s ign i f i cance o f the average f r i c t i o n s t ress r e s i s t i n g d i s l o c a t i o n motion being re1 ated t o the d i s l o c a t i o n s t r u c t u r e and i m p u r i t y e f f e c t s i n copper i s demonstrated. The amp l i t de dependen i n t e r n a l f r i c t i o n i n copper i n the decrement range o f 3 X 10. ' t o 2 X 101 i s shown t o be h y s t e r e t i c i n nature and can be analyzed by the KresselBrown and Roberts theor ies y i e l d i n g r e a l i s t i c d i s l o c a t i o n s t r u c t u r a l parameters.