Abstract
Electromagnetic forming (EMF), as a high-speed forming technology by applying the electromagnetic forces to manufacture sheet or tube metal parts, has many potential advantages, such as contact-free and resistance to buckling and springback. In this study, EMF is applied to form several panels with stiffened ribs. The distributions and variations of the electromagnetic force, the velocity and the forming height during the EMF process of the bi-directional panel with gird ribs are obtained by numerical simulations, and are analyzed via the comparison to those with the flat panel (non-stiffened) and two uni-directional panels (only with X-direction or Y-direction ribs). It is found that the electromagnetic body force loads simultaneously in the ribs and the webs, and the deformation of the panels is mainly driven by the force in the ribs. The distribution of force in the grid-rib panel can be found as the superposition of the two uni-directional stiffened panels. The velocity distribution for the grid-rib panel is primarily affected by the X-directional ribs, then the Y-directional ribs, and the variation of the velocity are influenced by the force distribution primarily and secondly the inertial effect. Mutual influence of deformation exists between the region undergoing deformation and the deformed or underformed free ends. It is useful to improve forming uniformity via a second discharge at the same position. Comparison between EMF and the brake forming with a stiffened panel shows that the former has more advantages in reducing the defects of springback and buckling.
Highlights
The development of the modern fuselage structure in aerospace industry makes it necessary to pursue possible methods to form the parts with a desired contour
In order toDiscussion study the influence of ribs on the formation of the stiffened panels, four types of
The forming rules of the bi-directional stiffened panels with grid ribs during the electromagnetic incremental forming (EMIF) process are studied by FE simulations aided by experiments
Summary
The development of the modern fuselage structure in aerospace industry makes it necessary to pursue possible methods to form the parts with a desired contour. The stiffened panels (integrally stiffened structure) have become one of the important parts of modern aircrafts, benefiting from their high strength, high structural efficiency and low weight. The stiffened panels forming technology, is one of the key technologies in aerospace industry. The improved structural stiffness of the stiffened panels, due to the stiffened ribs, increases the forming difficulty. Creep age forming (CAF), which appeared in the 1980s, is accomplished by combining creep forming and age hardening simultaneously. This process is widely applied in aircraft manufacture [2]. One of the key problems during CAF is the springback because the plastic strain level is very low and the elastic strain maintains a high level after forming [4]
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