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Press-fit connection
by Dr. Dušan Gabriel
Problem description
Consider a press-fit connection consisting of a shaft and a nave. Let the radii r2=2r1=1 m. The inner radius of the nave is less than the one of the shaft by the interference Δr1. Determine the contact pressure developed between the two parts.
Material properties
E=2×105 MPa, ν=0.3.
Support
Axisymmetric–plane stress.
Loading
Δr1=0.6667×10−3 m.
Solution
In the absence of external forces, we have no definite tolerance for the residual vector criterion, which, therefore, cannot be used directly for this and similar self-equilibrium problems. We may, however, control the magnitude of the out-of-balance vector in the .oL
file manually until it reduces to a ‘reasonable small’ value. To this end, we first execute the solver with default tolerance values on the RP line which will cause the program to stop after NITER iterations have been performed. When satisfied, we re-execute the solver with the convergence criteria disabled by setting RTOL=XTOL=−1 and the solution is obtained in the next iteration step.
The relation between the contact pressure pc and the interference Δr1 can be expressed as pc=EΔr1r1(1+r22+r21r22−r21)=2×1050.6667×10−30.5(1+1+0.521−0.52)=100 MPa.
The computed distribution of radial and hoop stresses in the shaft and nave with the penalty parameter set to ξ=1015 N/m3 is shown below. The analytical solution is plotted by a solid line.