FEA-based development of a new tool for systematic experimental validation of nonlinear strain paths and design of test specimens

Materials Research Proceedings

2023

Abstract. The material behaviour after non-proportional strain paths is subject of numerous current investigations. These investigations show that in addition to the stress state, a change in the direction of loading also has a significant influence on the material behaviour. In this work, the influence of non-proportional strain paths on the mechanical properties such as tensile strength, uniform strain, elongation at fracture and yield strength as well as the influence on formability is determined. For this purpose, a dual-phase steel CR330Y590-DP, with a thickness of 0.8 mm, is investigated in more detail. The material is pre-strained to different strain values and then further examined with Nakajima and tensile tests. The influence of the loading direction is determined by five different post-strain directions (0°, 22,5°, 45°, 67.5°and 90°) to the initial pre-strain direction. In addition to the method according to the standard, the yield strength is determined by a temperature-dependent determination method, which is based on the thermoelastic effect. This method has already been qualified for simple uniaxial tensile tests and a relation to the microstructural behaviour was proven. Thus, it provides valuable conclusions on the microstructural behavior for the tests performed within this study with a change in the loading direction.

Section: Methodsmentioning

confidence: 99%

Investigation of the influence of loading direction after pre-forming on the formability and mechanical properties of DP600

Materials Research Proceedings

2023

“…The pre-forming of the specimens has been realized on a hydraulic press using a modified Marciniaktool, proposed by Weinschenk and Volk [9], a more detailed description of the tool can be found there. The punch speed is set to a constant value of 15 mm/s and the blank holder force is set to 1200 kN.…”

Section: Methodsmentioning

confidence: 99%

Experiments on forming behaviour of the aluminium alloy AA6016

IOP Conf. Ser.: Mater. Sci. Eng.

Valencia

Gerke

et al. 2022

Investigation of the sheet metal formability is an important issue in the design of components. During metal forming different deformation histories occur which may cause various damage and failure mechanisms on the micro-level affecting the quality of products. Therefore, description of the material characteristics by means of a linear limit change curve is not sufficient because the remaining formability and the fracture processes also depend on deformation history. For this purpose the aluminium alloy AA6016 is systematically investigated in order to obtain their forming capability as well as the damage and fracture behaviour after complex deformation paths. Different uniaxial tests with various initially unloaded and preloaded specimens have been performed to identify the effect of the forming history, the loading direction and the stress state on the formability and the mechanical parameters of the investigated material. The results can be used to propose a critical ratio between the pre-strain and the change in loading direction from which on shear failure occurs instead of necking behaviour leading to the loss of formability.

“…To achieve different pre-strains, we used a specially manufactured tool and frequently used by us for this purpose on a hydraulic press [12]. This tool is shown in Figure 1.…”

Section: Pre-strain Conditionsmentioning

confidence: 99%

Innovative experimental setup for the investigation of material models with regard to strain hardening behavior

Maier

Eder

IOP Conf. Ser.: Mater. Sci. Eng.

et al. 2023

Sheet metal formed parts are often produced in multistage processes. The multi-directional deformations that occur in this process pose a challenge for sufficiently accurate modeling of the material behavior. In this paper, we present an experimental methodology and its potential that serves as a basis for a comprehensive validation of material models with respect to multi-directional deformation. Therefore, we present the experimental results of pre-strained DP600 specimens, which we afterwards subjected by the MUC-Test. The MUC-Test has already been established as a methodology for validating material models under proportional loading. By using pre-strained specimens, this methodology can be extended to non-linearities in the load history. For the purpose of the paper, we pre-strain the sheet material in three conditions: uniaxial tension, plane strain and equibiaxial tension. Thus, we show that the MUC-Test is suitable for the representation of multi-directional strain histories and useful for comprehensive validation of material models.