Forming limit of local loading forming of Ti-alloy large-scale rib-web components considering defects in the transitional region

Abstract

The forming quality in the transitional region largely determines the formability of local loading forming of the large-scale rib-web component. Thus, it is very critical to determine the forming limit considering defects in the transitional region during local loading forming. In this paper, the stepwise searching method based on Kriging metamodels of defect indexes is adopted to determine the above forming limit. First, the finite element (FE) simulation of the transitional region during local loading forming and the evaluation indexes for folding and cavum defects are introduced. Then, the Kriging metamodels of defect indexes are developed based on quantities of FE simulation results under various geometry parameters. During Kriging metamodeling, in order to guarantee the accuracy of the metamodel in the global design space and interesting region simultaneously, the space-filling maximin Latin hypercube designs (maximin LHDs) and sequential sampling approach are employed to design sample points. After metamodeling, extra random samples designed within the whole space are simulated to validate the developed Kriging metamodels. At last, the method of determining the forming limit considering defects in the transitional region is presented and applied to two specific transitional region models. It is realized through stepwise searching based on Kriging metamodels of defect indexes. The application results show that the proposed method is an effective and reliable method to determine the forming limit considering defects in the transitional region. It would provide an important guideline in the processing design of local loading forming of titanium alloy large-scale rib-web components.