Analysis of Tolerance Value on Torsion Bar and Output Shaft assembly for Automotive EPS

Torsion bar need to be pressed into output shaft for electrical power steering assembly, but the tolerance value should be determined when designing the torsion bar and output shaft model. There is initial penetration between torsion bar and output shaft finite element after meshing the 3D model, then study and eliminate the penetration, and find the maximum equivalent stress and deformation of X axis is 0 when offset value is -0.077mm after simulation based on different offset value . The tolerance value is calculated based on interfere fit between torsion bar and output shaft which let the torsion bar can not slip when 50Nm external load applied. Verify the analysis result by testing at test bench, and the test result is closed to the analysis result.