Effect of metal-composite layer thickness on springback after U-bending

A sudden increase in the usage of automotive vehiclesresults in sudden increases in the fuel consumption whichresults in an increase in air pollution. To cope up with thischallenge federal government is implying the stricterenvironmental regulation to decrease air pollution. To savefrom the environmental regulation penalty vehicle industry isresearching innovation which would reduce vehicle weight anddecrease the fuel consumption. Thus, the innovation related tolight-weighting is not only an option anymore but became amandatory necessity to decrease fuel consumption. To achievethis target, the industry has been looking at fabricatingcomponents from high strength to ultra-high strength steels orlightweight materials. With the usage of advanced high strengthsteels, the lightweight was achieved by reducing a gagethickness without compromising the strength aspect. Howeverdue to their high strength property often challenges occurredare higher machine tonnage requirement, sudden fracture,geometric defect, etc. The geometric defect comes from theelastic recovery of a material, which is also known as aspringback. Springback is commonly known as amanufacturing defect due to the geometric error in the part,which would not be able to fit in the assembly withoutsecondary operation or compensation in the forming process. Itis learned that the springback of the material increases with anincrease in the material strength and/or decrease in materialthickness. In advanced high strength steels, higher strength andlower gage thickness options make the part prone to higherspringback. Due to these many challenges, other research routeinvolved is composite material, where light materials can beused with high strength material to reduce the overall vehicleweight. This generally includes, tailor welded blanks, multilayer material, mechanical joining of dissimilar material, etc.Due to substantial use of dissimilar materials, these parts arealso called as hybrid components. It was noted that the partweight decreases with the use of hybrid components withoutcompromising the integrity and safety. In the previouslypublished paper in IMECE2017the study was focused on equallayer thickness of metal and composite in bilayer material. Inthis paper, a springback analysis was performed consideringbilayer metal by varying the thickness of the metal as well asthe composite. For this two dissimilar materials aluminum andcomposite was considered as bonded material. This materialwas then bent on a free bend die. The bilayer springback wascompared with different layer thickness of metal and compositeand in different condition like aluminum layer on punch sideand then on die side. These results were then compared with thebaseline springback of only aluminum thin and thick layer.