AN ADAPTIVE CONTINUUM/DISCRETE CRACK APPROACH FOR MESHFREE PARTICLE METHODS

Abstract

A COUPLED CONTINUUM/DISCRETE CRACK MODEL FOR STRAIN SOFTENING MATERIALS IS IMPLEMENTED IN A MESHFREE PARTICLE CODE. A COUPLED DAMAGE PLASTICITY CONSTITUTIVE LAW IS APPLIED UNTIL A CERTAIN STRAIN BASED THRESHOLD VALUE - THIS IS AT THE MAXIMUM TENSILE STRESS OF THE EQUIVALENT UNIAXIAL STRESS STRAIN CURVE - IS REACHED. AT THIS POINT A DISCRETE CRACK IS INTRODUCED AND DESCRIBED AS AN INTERNAL BOUNDARY WITH A TRACTION CRACK OPENING RELATION. WITHIN THE FRAMEWORK OF MESHFREE PARTICLE METHODS IT IS POSSIBLE TO MODEL THE TRANSITION FROM THE CONTINUUM TO THE DISCRETE CRACK SINCE BOUNDARIES AND PARTICLES CAN EASILY BE ADDED AND REMOVED. THE EFG METHOD AND AN EXPLICIT TIME INTEGRATION SCHEME IS USED. THE INTEGRALS ARE EVALUATED BY NODAL INTEGRATION, AN INTEGRATION WITH STRESS POINTS AND ALSO A FULL GAUSS QUADRATURE. SOME RESULTS ARE COMPARED TO EXPERIMENTAL DATA AND SHOW GOOD AGREEMENT. ADDITIONAL COMPARISONS ARE MADE TO A PURE CONTINUUM CONSTITUTIVE LAW.