椭圆形封头管口有限元分析加载方法的探讨

Discussion of Loading Mode in Finite Element Analysis for Nozzles on Elliptical Head

以标准椭圆形封头中心接管为分析模型,着重分析了其在设备内压、螺栓预紧力及垫片反力的共同作用下的真实应力状态,并与简化后的加载条件及模型的计算结果作对比,得出对于带法兰盘的封头开孔有限元模型,加载螺栓压紧力和垫片反力的模型与只施加内压轴向平衡压力的模型相比,法兰本身的应力强度最大值会大大增加,但孔边应力强度的计算结果相差不大,工程上可接受。对于不带法兰盘的封头开孔有限元模型,只加载接管端部内压轴向平衡压力的简化加载方法,计算出来的孔边应力强度最大值是偏保守的。开孔率越大,法兰盘对接管的加强作用越强。

In this article,regarding elliptical head connecting with central nozzle as the analysis model,the true stress distribution in the model which is loaded with inner pressure,bolt pre-tightening force and gasket reaction force was emphatically analyzed.By comparing with the result obtained by simplified loading condition and model,it was found that the maximum stress intensity in flange itself increased greatly in the first loading method,but the values of stress intensity at the conjunction of head and nozzle in both methods were very similar,so the second method is acceptable in engineering application.For the model without flange and loaded with inner pressure axial balance pressure on the end of nozzle,the stress intensity at the conjunction of head and nozzle is conservative.The bigger the nozzle is,the more strengthening effect the flange plate will give to nozzle.