Effect of welding on bearing capacity of launch vehicle tank based on Neuber formula

The maximum internal pressure in large launch vehicle tank made of 2219 aluminum alloy in the process of liquid bulge test was estimated according to Neuber formula. The small-area mechanical property of the joint was tested through micro-mechanical tests. The theoretical elastical stress concentration factor of welded toes at different structural models was obtained by linear-elastic finite element method. Finally, the small-area mechanical properties were adopted in the finite element model and the elastic-plastic structural analysis was carried out to verify the accuracy of Neuber formula in the calculating the bearing capacity of the tank. By comparison, the predicted local mechanical properties and stress concentration caused by geometrical defects seriously affect the bearing capacity of structure. Under extremely hazardous condition, the stress concentration factor could reach 5.156, and bearing capacity was only 1.21 MPa, as 37.81% of that one without weld. The stress variation of neuber formula was 8.5% and the strain variation was 2.3%, so the precision of Neuber formula is relatively high to estimate the bearing capacity of structure.