A method for making a three-dimensional principal stress theoretical forming limit diagram for plastic forming of pipes

Abstract

The invention discloses a pipe fitting plastic forming three-dimensional principal stress theory forming limit diagram manufacture method. The method comprises the steps that the pipe fitting is cut and manufactured to one-way tensile specimens, and a tensile test is conducted on the one-way tensile specimens to obtain basic parameters of the pipe fitting; on the basis of the basic parameters, a first ultimate principal stress and a second ultimate principal stress are obtained in different thickness direction stress conditions; according to a preset third principal stress, the first ultimate principal stress and the second ultimate principal stress, the three-dimensional principal stress theory forming limit diagram is drawn. According to the manufacture method, the basic parameters of the pipe fitting are obtained through the one-way tensile test, so that according to the basic parameters of the pipe fitting, the first ultimate principal stress and the second ultimate principal stress are obtained, and according to the first ultimate principal stress, the second ultimate principal stress and the preset third principal stress, the three-dimensional principal stress theory forming limit diagram is drawn; by introducing the thickness direction stress, the three-dimensional principal stress theory forming limit diagram is formed, and therefore the accuracy of pipe fitting forming limit prediction is improved.

Description

technical field [0001] The invention relates to the field of plastic forming of pipes, in particular to a method for making a three-dimensional principal stress theoretical forming limit diagram for plastic forming of pipes. Background technique [0002] The plastic forming of light alloy plates and pipe components has gradually developed into a dominant position in modern industrial production, especially in the fields of aerospace, automobile manufacturing, chemical light industry, and equipment manufacturing. According to statistics, the number of sheet metal forming parts accounts for 50% of the total number of aircraft parts and more than 75% of the total number of car parts. If it is replaced by light alloy materials, the overall performance of the product will be greatly improved. The important feature of plate and pipe components is that the dimension in the thickness direction is smaller than that in the length and width direction. Through forming processes such as ...

AI Technical Summary

Problems solved by technology

However, the characteristics of the new forming process make the adaptability of the given plane stress assumptions in the traditional thin shell theory questionable. reduced by nearly 90% and 60%, the yield ratio of the original pipe σ s / σ b Reduced from 0.899 of the original pipe to 0.174-0.359 after treatment; most high-strength aluminum alloy, magnesium alloy and titanium alloy pipes and plates need to be formed by warm forming process, and the strength and yield ratio of the material after heating will significantly reduce

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