THE SIGNIFICANCE OF J(3) TO THE PREDICTION OF SHEAR BANDS

The need to include the third deviatoric invariant J(3) in a yield fun ction is examined using the Mohr-Coulomb diagram. Two J(3) modified Dr ucker-Prager criteria are proposed to predict shear bands. The predict ions are compared to that of the Drucker-Prager criterion and verified by experimental data on Various polymers and a polyphenyl ether lubri cant from the open literature. The analysis procedure provides a means to deduce the orientation and magnitude of principal stresses from th e direction of shear localization observed in experiments. Copyright ( C) 1997 Elsevier Science Ltd.