Computational study of main bearing bore and bush deformation in assembly state

For the computation of loss of roundness and eccentricity based on the minimum zone circle method, an improved simplex optimization algorithm was proposed and used to study main bearing bore and bush assembling deformation. Simulated main bearing boring process in assembly by a finite element model updating method, the main bearing bush deformation under different pre-tightening forces and bush interferences was studied. The main bearing bore and bush assembling deformation was measured and partial computational results were validated. The results show that when maintaining the horizontal bolt pre-tightening force constant, the variation of the loss of roundness of main bearing bore is approximately linear with vertical pre-tightening force increase; the effect of friction coefficient between engine block and main bearing cap is negligible. The variation of main bearing assembling deformation with bush interference rise is linear generally; the loss of roundness of main bearing bush with considering the effect of boring process is about 2% of that without it.