Abstract: This paper presents new general deforming force formulae of the plane strain combined extrusion with smooth container by the unit deforming region technique of U. B. T. and standardization upper bound modes of combined extrusion are developed as well. A comparison is completed among values from the formulae and other theories as well as some experiments. It is shown that the results are quite identical either the perfect rigid plastic material or the strain-hardened material. The geometrical arrangement of U. B. T. can be obviously determined by use of these standardization modes. It is a simple and effective method to obtain a optimum solution of U. B. T. rapidly.

Key words: Fatigue failure, Hydraulic pipeline fittings, Load calibration test, regression analysis