On the Yield Behavior of Unplasticized P. V. C. : Analogy with the Yielding of Mild Steel

Abstract

We can recognize that there are two steps in the yield process of unplasticized P. V. C.. The first step of yielding is a process, during which the stress-strain curve reaches its maximum point and drops to the lower yield point ; we may call it the "initial yielding". The original local contraction can be seen in a part of the specimen. When such local contraction proceeded to a limiting value corresponding to the strain ε₁, a new yielding or contraction of the cross section is caused in the neighbouring part of yielded ; such yielding or the second step of yield may be called the "progressive yielding". The above two steps of yielding may be considered as analogous to the process of the upper and lower yield of the mild steel. Such phenomena of yielding are remarkably affected by the stretching speed ν_st. We established a relation between the stretching Speed ν_st and the yield strain ε₁, the velocity of propagation of plastic strain wave c, i.e. ν_st=c·ε₁.