基于Neuber公式的焊接制造对运载火箭储箱承载力的影响

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

利用Neuber公式对大型运载火箭的2219铝合金储箱液压过程中能够承受的内压力进行估算.其中,接头微区的力学性能通过微小力学试验得到,不同结构模型接头焊趾处的弹性理论应力集中系数通过线弹性有限元法得到.最后将微区力学性能代入有限元模型进行弹塑性计算,验证Neuber公式计算贮箱承载力的精度.对比发现,在承载力预测中,接头局部的力学性能以及几何缺陷引起的应力集中情况都会严重影响结构的承载力,极端危险条件下的应力集中系数可以达到5.156,而承载压力仅有1.21 MPa,为无焊缝时承载力的37.81%;Neuber公式的应力误差为8.5%,应变误差为2.3%,其估算结构承载力的精度比较高.

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.