Leather Viscoelasticity Of Study

In this paper, the stress-relaxation bahivior of pig shoe upper leather was studied by generalized Maxwell models. The expression of relaxation modulus and the rheological constants obtained by the model were used to calculate the stress relaxation-time spectrum in a second-order approximation method. The form of the spectrum was discussed in detail, and the relaxation-time spectrum can be used to describe the stress relaxation of leather well. The stress relaxation behaviors of five cattlehide shoe upper leathers with different strain were investigated. With stress relaxation measurement of cattlehide shoe upper leathers and a suitable curve fitting method, a three-dimensional stress relaxation diagram of cattlehide shoe upper leathers is built up. This stress-strain-time coordinate diagram can be used to predict the stress of leathers in different strain and relaxation time. The relaxation rate of different relaxation units in pig shoe upper leather was studied with stress-relaxation experiments of the leathers with different strain. Both the behaviors of stress-relaxation and stress-strain of different leathers were demonstrated having a close relationship with the leather's service performance and procedures in leather making.The influences of humidity and strain on the mechanical properties of pig soft leather were studied with stress-strain curves obtained by uniaxial tension experiment. The set and mechanical behavior of partially processed pig soft leather has also been investigated in this paper. High values of set were produced by drying under strain and the tensile moduli of the leathers with set were raised obviously with the increase of the strain. The pig soft leather shrinks with the decrease of the relative humidity of the air in which it was placed. The area of the leather dropped sharply with the decrease of the relative humidity of the air, but there is no great difference in the shrinkage rate for different locations of the leather.