A strain based criterion for creep crack initiation
Commonly,for components under creep loading,the maximum tolerable inelastic strain is limited to 1 %.The strains are calculated for components which are free from defects,using appropriate material models.Within the fabrication process internal defects such as crack or cavities cannot be avoided,especially for large thick-walled components.For these internal defects fracture mechanic concepts must be applied for safety assessment.Existing fracture mechanics concepts such as the Two-Criteria-Diagram or the Time-Dependent-Failure-Assessment-Diagram do not include the effect of the materials ductility which has a clear effect on crack initiation process.Under creep load,the strains within the crack tip region dominate local material separation.Therefore a concept is introduced,which formulates a deformation exhaustion rule.With this procedure a better material utilisation is achieved.In a next step,crack initiation is calculated using an internal damage variable,which can be used as a life time parameter.Within this approach,the influence of a multiaxial state of stress on the damage evolution must be implemented.This procedure simplifies crack initiation assessment,replacing fracture mechanic methods by the evaluation of the damage variable.
Creep crack initiation failure criterion creep strain
A.Hobt A.Klenk K.Maile
MPA University of Stuttgart,Pfaffenwaldring 32,7569 Stuttgart Germany
国际会议
北京
英文
1-9
2013-06-16（万方平台首次上网日期，不代表论文的发表时间）