Finite Element Analysis On The Plastic Limit Load Of Welded Piping Tee Under The External Load

Piping tee,as one of the important components in pressure piping system,is widely used in petrochemical engineering,power plant and oil gas transportation etc.．Because of the geometric complexity of the tee and the difficulty of mathematic analysis,there has not been yet a mature and simple stress computing method．Considering the general failure mode of the piping tee is plastic failure, the plastic limit load for the piping tee is an important design parameter in engineering．By means of the non-linear finite element analysis,the defect-free tee under bending moment was researched in this paper．On basis of the limit load solutions of defect-free tee,the influence of the locally-thinned defect of the tee under moment and combined load on the plastic limit load was analyzed in detail．The main contents and achievements were summarized as follows:(1) The three-dimension finite element models of both defect-free and defected welded piping tee were established．The suitable preprocess programs for the subject were made．(2) The plastic limit moment database about piping tee were built,and the effect of the geometric sizes on the plastic limit moment for piping tee were investigated．(3) By simplifying the effect factors of the bottom-thinned tee's plastic limit load,the plastic limit load of different bottom-thinned tee under moment or combined loads was gained．Meanwhile,the relation between the plastic limit load and main effect factors were studied,and the failure mode of the bottom-thinned tee's was presented.(4) Based on the finite element analysis,the engineering estimated formulae of tee's plastic limit load under external load were fitted．...