有限ひずみ域での引張・ねじり組合せ負荷におけるポリエチレンおよびポリプロピレン材の応力-ひずみ曲線

抄録

In order to investigate a constitutive equation at finite strains for crystalline polymers of polyethylene (PE) and polypropylene (PP), stress responses were investigated under various strain paths such as proportional, cruciform, circular paths and cyclic ones under combined tension-torsion. It was shown that ( 1 ) for creep tests at relatively low stress, creep strain increases with an increase in time, and the ratio of torsional to axial strain is nearly equal to the ratio of torsional to axial stress, ( 2 ) the degree of a cross hardening or softening caused due to a change in the principal deformation direction is much less than that in steel and ( 3 ) the strain history greatly influences to the stress-strain behavior of PP, but not PE.