Forming defects control in transitional region during isothermal local loading of Ti-alloy rib-web component

Abstract

The forming quality of transitional region plays a key role in the performance of titanium alloy large-scale ribweb component under isothermal local loading forming. In this work, a local eigen model of transitional region in the local loading forming of large-scale rib-web component is extracted so as to catch the detail-forming characteristics of transitional region with low computation time in simulation and experiment cost. Then, based on the local eigen model, the mechanism of forming defects in transitional region and their dependence on processing parameters are studied by the combination of physical experiment and verified finite element (FE) simulation. It is found that the second loading step can be divided into two forming stages according to the material flow pattern: (1) the transverse flow stage and (2) the stable forming stage. In the transverse flow stage, there exists long-range transverse flow of web material and excessive transverse flow would lead to the formation of folding and cavum defects. Moreover, the severities of defects are well correlated with the quantity of material transferred into the first-loading region in this stage. For a certain reduction amount, decreasing spacer block thickness and increasing friction both can decrease the quantity of transferred material and then suppress the development of folding and cavum defects, while the deformation temperature and loading speed have little effect on the quantity of transferred material and defects. In the end, an effective way is put forward to suppress and prevent the defects in transitional region during the local loading forming of titanium alloy large-scale rib-web component.

Robust optimization of consistency in filling of rib-grooves for titanium alloy multi-rib eigenstructure

“…Orthogonal design by inside and outside array is an experimental design, in which two experimental design tables are arranged vertically to examine the influence of one factor on another, taking into account both deterministic and uncertain factors [34,21]. Based on the inner array and the outer array of robust design, the geometric parameters of UTB are arranged in the outer array with Box-Behnken design (BBD), and the uncertainty factors, such as billet manufacturing deviation, die manufacturing error and friction factor are arranged in the inner array with Uniform Design (UD), as shown in Table 5.…”

Robust optimization of consistency in filling of rib-grooves for titanium alloy multi-rib eigenstructure

“…Orthogonal design by inside and outside array is an experimental design, in which two experimental design tables are arranged vertically to examine the influence of one factor on another, taking into account both deterministic and uncertain factors [34,21]. Based on the inner array and the outer array of robust design, the geometric parameters of UTB are arranged in the outer array with Box-Behnken design (BBD), and the uncertainty factors, such as billet manufacturing deviation, die manufacturing error and friction factor are arranged in the inner array with Uniform Design (UD), as shown in Table 5.…”

Practicality and formability of integrally stiffened tube hydro-assisted forming

“…The forming technology of such component is a key technology which has great impact on the development of airplane. To solve this problem, some scholars analyzed spinning forming [5,6] and isothermal forging technologies [7,8]. But the results indicate that these technologies can only be used to form the components with thickness bigger than 3 mm, which was far thicker than that needed in modern warplanes.…”