Hydroforming

About: Hydroforming is a research topic. Over the lifetime, 2796 publications have been published within this topic receiving 26293 citations. The topic is also known as: Bulge forming.

Deformation characteristics in hydro-mechanical forming process of thin-walled hollow component with large deformation: experimentation and finite element modeling

Abstract: The automobile exhaust manifold regularly has a multi-valved shape that used to be formed by the combination of stamping and welding. The current study intended to investigate and develop a tube hydro-mechanical forming (THMF) process to form an integral automobile exhaust manifold that has the characters of large deformation and small corner. It included three stages such as pre-forming stage, die-forming stage, and calibration stage. In addition, the non-feasibility of one-step hydroforming process was proved by FE modeling and experimental for the target component. An optimal loading path was obtained through the principle of dichotomy for pre-forming stage and die-forming stage, corresponding to the maximum thinning ratio of 19.7% and 13.27% respectively. The variation of stress and strain states were analyzed for the whole process. As a consequent, the thickness distribution exhibited a V-shaped along axial direction at each stage, while a fluctuated distribution after die-forming was presented along radial direction in the multi-valved area. For the final component, a maximum thinning ratio of 28.53% and the large deformation above 60% obtained from FE modeling kept a reasonable agreement with that achieved from experiments. It showed that THMF has advantages of not only decreasing the internal pressure but also improving the formability of tube.

Method for hydroforming tubular body

Abstract: PROBLEM TO BE SOLVED: To provide a method for preventing defective formation due to cracks and wrinkles by allowing loading path not to cause the appearance region of the cracks and the wrinkles when hydroforming a tubular body by the combination of the internal pressure and the forcing amount of a shaft into the tubular body. SOLUTION: The limit line W of crack and the limit line S of wrinkle-buckling between the internal pressure and the forcing amount of the shaft are beforehand prepared in accordance with the material and the size of a tube stock to be worked and a shape to be formed, and the internal pressure and the forcing amount of the shaft are imparted from the beginning of the start of the working so that the loading paths (1), (2) pass through the limit line W of crack and the limit line S of wrinkle-buckling. COPYRIGHT: (C)2004,JPO&NCIPI

Microstructural evolution and failure mechanism of an extrusion welded aluminum alloy tube during hydroforming processing

Abstract: During hydroforming of Al alloys, cracking often limits the production of specific frames for next-generation transportation vehicles. In this study, microstructural evolution and cracking behavior of an extrusion welded aluminum alloy blank tube were characterized to uncover the failure mechanisms during hydroforming process. Electron back-scattered diffraction, transmission electron microscope, and scanning electron microscope were employed to characterize the grains, textures, and local micro-crack sites. Experimental results demonstrated that grains in the welds region were significantly larger than those in the neighboring regions. Along the weld region, large grains typically with high-misorientation with respect to neighboring grains were identified as the preferred crack nucleation sites. Plastic incompatibility due to preferential yielding in the larger (softer) grains as compared to the surrounding finer (harder) grains is postulated as the origin for local strain localization that leads to cracking in the weld regions during hydroforming.

Study on the forming of sandwich shells with closed-cell foam cores

Abstract: The efficiency and safety of vehicles represent today one of the most important lines of developing in the automotive industry, for example by the introduction of new materials. In fact, the investment in advanced materials represents one of the most important strategies to reduce injury among vehicle occupants in traffic accidents. Associated with the development of safety systems, there is also the possibility of improving efficiency by the introduction of materials that lead to weight reduction, having a direct impact on fuel consumption and carbon dioxide emissions. Metallic foams are one of these materials, due to the excellent ratio between mechanical properties and density. The main goal of this investigation is to study the mechanical behaviour of aluminium sandwich structures, composed by a metallic foam core with two outer layers of metallic sheets. With this work, the authors intend to contribute to a better understanding and consequently to provide design guidelines for the plastic forming of these composites. In order to correctly characterize the mechanical behaviour of the sandwich structure, the foam core and sheets were tested separately. For the aluminium sheet a series of tensile tests were performed, using samples obtained along three different angles to the rolling direction. For the metal foam core, uniaxial compression tests were used. Finally, with the numerical model defined considering isotropic and anisotropic constitutive models, a set of numerical and experimental bulge tests were performed to evaluate the capacity of forming of these panels, using hydroforming processes.