Abstract
Press-braking bending is widely applied in the manufacture of aircraft integral panels because of the advantages of strong adaptability to different contours, simplicity of bending tools, short manufacturing time and low process cost. However, a simulation of bending process requires long-time calculation and consumes extensive computational resources. Considering the factors that the original model (ORM) of an integral panel is large and the press-braking bending is used only for the local area of integral panels with heavy thickness in practice, an equivalent calculation method for press-braking bending analysis of integral panels is proposed. The local bending area of an integral panel is simplified to a model of plate in this method. An exponential strengthening model is used to derive the equations of stress, strain and forming radius of the ORM and its simplified model (SPM). Meanwhile, the equivalent parameters of the SPM are determined and deduced based on three principles: that the material begin to be yielded simultaneously, the ultimate stress of the ORM is the same as that of the SPM at the same punch displacement, and the forming radii of neutral surfaces of the ORM and the SPM are identical after springback. The distribution of the stress and strain determined by finite element (FE) simulations are compared, and the FE simulations indicate that the contour curve of the SPM is in fairly good agreement with the profile of the ORM under the same bending process parameters, and the maximum difference is 13.17%. The computational efficiency is increased by more than 48%. Therefore, the proposed approach is quite suitable for industrial applications to improve the bending quality and efficiency of integral panels.
Highlights
Aircraft integral panels have been widely used in aerospace vehicles due to their advantages of lightweight design, high strength, and high structural efficiency [1,2,3]
The efficiency of finite element (FE) simulation calculated with simplified model (SPM) is compared with original model (ORM) analysis
An equivalent calculation method for press-braking bending analysis of integral panels is proposed to solve the problem that long-time calculation and extensive computational resources are required for simulating the bending forming process with an ORM
Summary
Aircraft integral panels have been widely used in aerospace vehicles due to their advantages of lightweight design, high strength, and high structural efficiency [1,2,3]. The dimensions of an aircraft integral panel are quite large, and the stiffeners are plentiful and complicated, which lead to tremendous meshing and calculating time This press-braking bending process consists of multiple times of bending and springback. The accuracy of the equivalent models established by the aforementioned literature is acceptable, the following limitations still exist: (1) The errors because of the integrally stiffened panel being directly equivalent to a rectangular thin plate are large due to the structure changes; (2) The stress and strain distribution of the forming process are not analyzed and evaluated in detail; (3) The main equivalent parameters are almost not analyzed, and the consistency of the contours between the ORM and the SPM should be guaranteed as far as possible under the same bending process parameters;. Are compared, and the contours at the end of the forming process are compared between the FE models and the experimental results
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