42nd International Deep Drawing Research Group Conference - IDDRG 2023

Cost and time for die tryouts are significant within the car industry. A major contributing factor is that elastic deflections of dies and presses are usually not considered during the virtual die design and forming simulation phase. Active surfaces of stamping dies are only cambered based on previous experiences of tool types and presses. However, almost all stamping dies and presses are...

In a deep drawing process, the friction at the sheet metal-die contact interface affects the material flow in the flange as well as in die entry radius region, affecting product quality significantly. The accuracy of predicted drawing force and thinning in deep drawing simulation strongly depends on friction modelling. The Coulomb’s friction model with a constant coefficient of friction is...

The use of Advanced High Strength Steel (AHSS) allows for lightweighting of sheet steel components, with maintained structural integrity of the part. This has enabled a wide-spread use of the materials and an ever increasing development of new, even stronger AHSS grades. However, with increased strength comes limited formability. Thus, the use of conventional cold forming processes is not...

Abstract: Uncoupled ductile fracture models have gained popularity for accurate prediction of fracture in ductile metallic sheets due to their ease of implementation. Accurate description of anisotropic fracture behavior is an active research field for sheet metal forming. In the present study, three isotropic ductile fracture models, i.e., modified Mohr-Coulomb, Hosford-Coulomb and DF2016...

Dual-phase steels (DP steels) consist of ferrite and hard martensitic phase. As they combine high strength and good formability at low production costs, they are widely used for automotive applications. Compared with the DP steels with lower strength, the DP1180 steel is more special for the volume fraction of martensite is higher than that of ferrite. In this paper, the evolving plastic...

Anisotropy plays a significant role in engineering, especially in the field of sheet metal forming. This particular characteristic stems mainly from the crystallographic structure of the metals and the influence of the rolling process, inducing preferred orientations of the grains. In this context, the crystal plasticity theory plays an important role as it accounts for the anisotropic nature...

In this study, a new test method using protruding punch was proposed, that can separate bending and stretch deformations. In this test, the blank contact with the top and shoulder of punch, and the bending angle can be constant. After the bending angle becomes constant, stretch deformation can be applied while the bending deformation remains constant. In addition, this test method can control...

ABSTRACT
The calibration of material data to properly describe the stress response of a specific material under various loading conditions in finite element analysis (FEA) is still a challenging task. Not only that new steel grades or aluminum alloys are investigated by the material manufacturers to enhance certain characteristics of their product such as stiffness, strength, or maximum...

Sheet metal forming (SMF) simulations are traditionally carried out with rigid active forming surfaces. This means that the elasticity and dynamics of presses and die structures are ignored. The only geometries of the tools included in the simulations are the active forming surfaces. One reason for this simplification is the large amount of computational power that is required to solve finite...

Sheet metal forming (SMF) simulations are traditionally carried out with rigid tool surfaces. This research aims to enable simulations with elastic dies for industrial-sized stamping dies. This is important for die try-out, digital twins, production control, and other topics in the current frontier of SMF research. No method in the literature is fully developed for simulations with industrial...

ABSTRACT
In finite element analysis (FEA), improving the accuracy of the prediction capability of material cards to obtain the correct stress response of a specific material is still a major challenge in the field of forming technology. Furthermore, new aluminium alloys or steel grades are steadily released by the material manufacturers, differing in their attributes such as stiffness,...

Recent developments aimed at reducing cumulative CO2 emissions in the energy sector and e-mobility are leading to an increase in the production volumes of formed components made from thin metallic foils used for alternative energy supply concepts. Thus, components such as bipolar plates in fuel cells and a variety of parts in e-motors and batteries are being manufactured in ever higher...

The Yoshida-Uemori model is a combined hardening model coupled with the elastic evolution modulus which depends on the equivalent plastic strain. This model is implemented in the most used FEA stamping codes with occasionally some variations in the form of material cards. The material cards are requested regularly by the car manufacturers, in order to get a more accurate prediction of...

Virtual experiments based on crystal plasticity simulations are a common approach to predict the texture-induced plastic anisotropy of polycrystalline sheet metals. Such simulation approaches utilise a crystal plasticity constitutive model that describes the deformation behaviour of single crystals on the base of crystallographic slip. However, there are different mathematical formulations of...