In this paper, stress intensity factors of multiple cracks in thick-walled cylinders subjected to thermal load have been determined by means of th integration, using FEM. The proposed programme can also be applied to the computation of the stress intensity factors for other plane problems under the loadings of either mechanical forces or temperature fields or both. In the meantime, this progrom has provided functions to form meshes of elements and compute coordinates of nodes automatically. A. practical example... In this paper, stress intensity factors of multiple cracks in thick-walled cylinders subjected to thermal load have been determined by means of th integration, using FEM. The proposed programme can also be applied to the computation of the stress intensity factors for other plane problems under the loadings of either mechanical forces or temperature fields or both. In the meantime, this progrom has provided functions to form meshes of elements and compute coordinates of nodes automatically. A. practical example for the polyethlence reaction cylinders has been given in the final part of this paper, in which the number of cracks are taken as 1, 2, 4, 8, 16 and 36. The functional relations between the stress intensity factors and crack numbers as well as crack depth are obtained. Besides, some features of the stress intensity factors for the case of internal multi-cracks are also discussed and then the fatique life can be predicted. According to the analysis proceeded above, some conclusions can be made as follows:(1) The stress intensity factors decrease with the crack number increasing from 2 to 36.(2) The values of stress intensity factors for one crack and four cracks are very close as the crack depth α/H<0.4. But when α/H>0.4, the value of SIF for one crack drops rather quickly.(3) The stress intensity factors increase with the increase of crack depth when it is subjected to mechanical forces, and just on the contrary when it is subjected to temperature fields.(4) When the crack depth α/H≤0.01, the influence of crack number on the stress intensity factors is not great.( 5) The results obtainted by means of the displacement method, stress method, J-integration using FEM are essentially in agreement with one anotherBesides, there are also some similar features for the different radius ratio of the cylinders. |