EFFECT OF METAL-COMPOSITE LAYER THICKNESS ON SPRINGBACK AFTER U- BENDING

摘要

A sudden increase in the usage of automotive vehicles results in sudden increases in the fuel consumption which results in an increase in air pollution. To cope up with this challenge federal government is implying the stricter environmental regulation to decrease air pollution. To save from the environmental regulation penalty vehicle industry is researching innovation which would reduce vehicle weight and decrease the fuel consumption. Thus, the innovation related to light-weighting is not only an option anymore but became a mandatory necessity to decrease fuel consumption. To achieve this target, the industry has been looking at fabricating components from high strength to ultra-high strength steels or lightweight materials. With the usage of advanced high strength steels, the lightweight was achieved by reducing a gage thickness without compromising the strength aspect. However due to their high strength property often challenges occurred are higher machine tonnage requirement, sudden fracture, geometric defect, etc. The geometric defect comes from the elastic recovery of a material, which is also known as a springbuck. Springbuck is commonly known as a manufacturing defect due to the geometric error in the part, which would not be able to fit in the assembly without secondary operation or compensation in the forming process. It is learned that the springbuck of the material increases with an increase in the material strength and/or decrease in material thickness. In advanced high strength steels, higher strength and lower gage thickness options make the part prone to higher springbuck. Due to these many challenges, other research route involved is composite material, where light materials can be used with high strength muteriul to reduce the overall vehicle weight. This generally includes, tailor welded blanks, multilayer muteriul, mechanical joining of dissimilar material, etc. Due to substantial use of dissimilar materials, these parts are also called as hybrid components. It was noted that the part weight decreases with the use of hybrid components without compromising the integrity and safety. In the previously published paper in IMECE2017the study was focused on equal layer thickness of metal and composite in bilayer material. In this paper, a springbuck analysis was performed considering bilayer metal by varying the thickness of the metal as well as the composite. For this two dissimilar materials aluminum and composite was considered as bonded material. This material wus then bent on u free bend die. The biluyer springbuck was compured with different luyer thickness of metal and composite and in different condition like aluminum layer on punch side and then on die side. These results were then compured with the baseline springbuck of only aluminum thin and thick layer.