EVALUATION OF DISSIPATION ENERGY OF ISOTROPIC CONTINUUM DAMAGE MECHANICS MODEL WITH ADAPTIVE TIME-STEP CONTROL APPROACH

Abstract

This paper proposes an algorithm to evaluate dissipation energy of an isotropic continuum damage mechanics model with an adaptive time-step control approach. The algorithm takes place at each integration point under the scope of finite element analysis. The total amount of the dissipation energy of one structure can be used to verify the conservation law of energy, where the summation of the elastic strain energy and the dissipation energy should be equal to the total work by external force. However, the paper shows that this condition may not be valid when the unstable crack propagation occurs. When the crack propagation is unstable, the development of damage can be driven by stored strain energy without external load. The strains at the beginning and ending time within one increment at the damaged elements will give inaccurate dissipation energy by the classic trapezoidal integration scheme. In addition, this paper proposes a new damage evolution shape function with C1 continuity of the strain-stress curve under the uniaxial tension test, which is used to demonstrate the numerical procedure of the adaptive algorithm.