Firas Jarrar

Constitutive Modeling for the Simulation of the Superplastic Forming of AA5083

The AA5083 alloy is already being used in applications that require lightweight construction and moderate strengths. In order to carry out accurate simulations of the superplastic forming of this alloy, the used constitutive models should be able to predict the deformation and thinning behavior during the forming process. In this paper, we compare the dome height and pole thickness evolution during gas bulge forming using different AA5083 constitutive material models. The models considered have different levels of complexity and are fitted using either tensile or biaxial experimental data. The simulation results are also compared with experimental data from literature. In addition, recommendations are made for developing accurate material models for the considered AA5083 alloy.

Inclination Angle Effect on the Thickness Distribution in a Superplastic Formed Long Rectangular Pan

In the superplastic process, the non-uniformity of the produced part thickness and the possibility of severe thinning are among the major disadvantages. This paper presents a parametric study on the superplastic forming of a Pb-Sn sheet into the shape of a long rectangular pan. A two dimensional plain strain finite element model was used to predict the forming times and thinning profiles of the formed Pb-Sn pan. The effect of varying the sidewall inclination angle was investigated for different friction conditions at the die-sheet interface. Results showed that increasing the side wall inclination angle reduced the forming time and provided a better thickness distribution.

Defects and Remedies in Stamping of Advanced High Strength Steels

Abstract: In recent years, the use of advanced high strength steels (AHSS) in the automotive industry has increased due to their potential in reducing weight, leading to lower fuel consumption and carbon dioxide emissions. The AHSS structures would be the optimum choice for many applications; however, there are many defects to overcome in their stamping. In this present study, different types of defects and remedies of AHSS stampings are presented. Keywords: Advanced high strength steel, AHSS, Failure analysis, Damage behavior of multiphase steels, Failure prediction. 1. INTRODUCTION Lightweight materials, such as composites, aluminum, and magnesium alloys are commonly used in the automotive and aerospace industries. However, when lower density materials (such as Al and Mg alloys) are used, thicker parts are required to compensate for their lower strength. In addition, there are some difficulties in the cold forming of such low-density alloys. After the oil crisis in the 1970s, the steel industry has started to develop the dual-phase (DP) steels (ferritic-martensitic) in order to decrease fuel consumption and exhaust tail pipe emissions. DP steels are part of broader type of steels which are known as advanced high strength steels. These AHSS offer up to five times the strength relative to the mild steels. Therefore, they can be an attractive alternative to lightweight materials in achieving lightweight structuring. Obviously, AHSS are not considered to be lightweight materials, however; due to their high yield strength, the sheet thicknesses can be significantly reduced and consequently weight reduction can be achieved. Advanced high strength steel tubes are currently used as side impact door beams, seat structures, and instrument panel beams in automobiles [1]. AHSS have been being increasingly used in automobile structural components due to their corrosion resistance, toughness, and high resistance to impact. In specific, Martensitic Steels (MS) are typically used to provide collision protection by minimizing the deformation from sideward impacts [2]. A more extensive use of AHSS in the automotive industry would cause a significant reduction in weight without