A thermo-mechanical study of mode I, small-scale yielding crack-tip fields in glassy polymers

The objective of this work is to study the stress and temperature fields ahead of a blunted notch under mode I, small-scale yielding situations. The investigation is motivated by the observation that certain polymers and polymer blends exhibit a marked increase in fracture toughness with increase in loading rate. To this end, the thermo-mechanics of glassy polymers within the framework of finite deformation elasto-viscoplasticity is discussed along with a finite element procedure to solve the resulting coupled equations. The results indicate that heat diffusion from the plastic zone leads to wider shear bands and larger heat-affected zones. Moreover, increase in loading rate has a noticeable effect on the rate of temperature rise, crack-tip opening displacement and the stress intensity factor at which crazing is expected to initiate in front of the crack tip.