Since The Finite Element Analysis, Enhanced Ultra-high Pressure Elbows

Superhigh pressure curved pipe is a pipeline element of supperhigh pressure equipment, whose quality and carrying capacity directly affect safety run and life of application of all ductworks. The carrying capacity and fatigued life of a equipment can be heightened by autofrettaged before it served. A finite element analysis calculational model was established with ANSYS. A curved pipe was a example whoseφ×t = 78×22, the relative bend radius (R/D=2-10), whose distributing rule of elasticstress about R/D was analysised when it is loaded in inside pressure, the approximate calculating formula of the elastic stress was gained, and confirmed the internal side of internal wall is the dangerous point. The programme about the plasticity analysis of superhigh pressure curved pipe was programmed with APDL of ANSYS, calculation proved that the plastic limited load is independent of outer diameter, and which is relational about R/D and K. 25 different curved pipes whose material is 34CrNi3MoA were calculated and the approximate calculating formula of limited load which is correlative with R/D and K based on Von Mises yield rule was gained. A superhighpressure curved pipe was a example, whose φ×t = 78×22 and R/D=3, its plasticstress and residual stress's distributing rule was gained. The failure of superhigh pressure curved pipe may be resulted by static strength and fatigue crack. The theoretic optimum overstrain pressure of the curved pipe based on Tresca yield rule and equal static intensity rule and based on fatigue strength was gained.