FEM ANALYSIS OF THERMAL STRESS DISTRIBUTION NEAR THE CRACK TIP BASED ON FCM CONCEPT

摘要

Based on the Fictitious Crack Model (FCM) and Duan- Nakagawa's Model concepts, Some model fracture problems with the fracture process zone subjected to uneven change of temperature are analyzed in this paper. Except the fracture process zone, the whole specimen is assumed as elastic. According to the linear relationship of stress and crack opening displacement on the process zone (the tensile strain softening curve), the fictitious free-mass springs whose stiffness varies with the displacement on the nodes of the fictitious crack, are added on the process zone. Controlled by the tensile strength f1 and the critical crack tip opening displacement (CTOD <,C>), the stress and the displacement distribution, the fracture process zone initiation and development of the concrete specimen with the general load increasing are analyzed by the finite element method. As a practical example, the whole fracture processes is simulated, which is an edge notched beam with simply supported or fixed at two ends subjected to the temperature difference between the top and the bottom faces. The results show that the calculation is stable and holds some reference values in the practical civil engineering.