Based on the axisymmetric and 3-D finite element models, the axial-load and stress distributions on each thread of the threaded connection have been studied. The effect of helix and the elastic-plastic behavior of the material at the thread roots have been explored. Simulation results indicate that the axial-load and stress distributions obtained from the axisymmetric finite element model show good agreement with the results of 3-D analysis in both elastic and plastic states with the same mesh density. So the axisymmetric model can be used to study the axial-load and the stress distributions of the threaded connection subjected to axial-load. The axial-load and stress distributions in threads are very sensitive to the applied load. With increasing the applied forces, the axial-load and stress distributions over teeth become homogeneous eventually.

Self-loosening is one of the major failure reasons for bolted joints. Utilizing the finite element method, a 3-Dimension finite element model under dynamic shear loading is built to study the loosening of bolted fastener phenomenon. And the effect of increment step length, initial clamping force, amplitude of the shear load, thread tolerance, friction coefficients on the loosening process are studied.

The stresses around the fillet of fillet rolled crankshaft section in bending fatigue test are quite complicated, which include the residual stresses induced by fillet rolling process and bending stresses caused by bending fatigue test loads. In this paper, the corresponding three dimensional finite element models of roller- shaft are created and the residual stresses near the fillet of crankshaft section are obtained by flexible-flexible contact computation. Then the transient analysis of bending fatigue test based on modal superposition method is carried out and the bending stresses are got. The results of stress can be used to the bending fatigue design of crankshafts.

For the fracture failure phenomena occurred in random vibration experiment of the isolation clamp cylinder on the aerospace vehicles, the NX NASTRAN was used to make the finite element modeling for the overall structure of cylinder and analyze the random vibration response. The simulation results show that the maximum RMS stress of the clamp was 96 MPa at the test load conditions. The position of the maximum RMS stress is consistent with the one where fracture happens during vibration test. According to finite element analysis results, the original structure has been modified. The maximum RMS stress of modified structure is only 21.8 MPa.

To study the effects of the nonhomogeneous material properties on the stress in an induction quenched crankshaft, the FEM model considering the nonhomogeneous material properties was established to simulate the stress in the crankshaft under the explosion pressure. Results showed that the nonhomogeneous properties almost didn’t vary the Mises stress distribution rule in the crankshaft. The maximum Mises stress, the ratio of the elastic modulus of the surface layer and the matrix followed a linear rule nearly. Moreover, the maximum Mises stress increased with the ratio. Besides, effect of elastic modulus distribution in the transition layer on the maximum stress could be ignored. To simplify the establishment of the FEM model, the elastic modulus could be set to either equal to the surface layer’s or the matrix’s.