List of Abstracts 2016: SESSION C - SIMULATION OF TECHNOLOGICAL PROCESSES AND MATERIAL
Date: November 10, 2016
A well-known method of materials formability description is the Forming Limit Diagram (FLD) where FLC (Forming Limit Curve) represents major and minor principal strains present in the plane of deformed sheet corresponding to the occurrence of the necking. The current paper is dealing with anisotropy influence on FLC. This effect is going to be studied with the use of mild steel DC01. Uniaxial tensile tests were performed for basic characterisation of sheet samples with the use of contact-less measuring devices. Hills anisotropic criterion is considered here and for its application experimental investigation has to be carried out in order to provide input data for the model applied. In order to assess the anisotropy experimentally, the specimens were extracted and tested in Rolling Direction (RD), Transverse Direction (TD) and 45° Skew Direction (SD) for the Lankford ratios determination. Detailed stress state description of the material investigated was carried out with the use the stress triaxiality and Lode angel parameter and transformations from conventional space into stress state provide a profound insight into the necking phenomenon. According to the experimental and numerical results it was found, it is necessary to take anisotropy effects into account for the material investigated.
In this paper, cyclic plasticity response of 08Ch10N10T austenitic steel under large strain amplitude loading is presented. Non-Masing behaviour and strain-amplitude dependent cyclic hardening is observed and analysed. Impact on testing and modelling associated with this phenomenon are described.
To face challenges like damping effects or weight reduction in the automotive sector, new hybrid material combinations are developed. One possibility is the combination of several symmetric material layers with varying material characteristics to achieve in the component production less weight and appropriate stiffness in comparison to components produced with sheet metal. This article deals with the characterization of deep drawing behaviour of layered sandwich structures. The behaviour of the several layers and the layer interaction have been taken into account for the technical design of a deep drawing process. An material layer characterization is performed. Instabilities as interlaminar failures, ruptures or wrinkling of the structure have been investigated as part of additional experimental characterization tests on the basis of various deep drawing process parameters. Finally, the experimental data is used as input for the numerical modelling and simulation of layered structures. The FE simulation includes the material behaviour of the layers and layer interactions with cohesive zone modelling. Based on the results an important contribution for prediction accuracy in the numerical simulation has been provided.
The aim of this study was the evaluation of the parameters for the material model description in simulation of plasticity and fracture in shearing processes. The experimental measurements and the simulations were performed at room temperature for TWIP steel and 38MnVS6. The behaviour of materials was described using MARC/MENTAT and DEFORM software based on the finite element method. The material model was made up on the basis of tension test. The fracture criteria were based on the experimental failure during tension and torsion tests. The fracture models Normalized Cockcroft-Latham and Oyane were used for subsequent simulation of shearing. The description of shearing comprised not only the initiation of a fracture but also the growth of the fracture until the material parts are separated. This issue was solved by means of two numerical methods, the softening and the element deletion.
Date: November 11, 2016
By sheet metal forming processes the forming limits and component characteristics are defined through the process specific loads. In deep drawing processes the maximum deep draw ratios as well as the springback behaviour of the metal components are depending on the stress distribution in the component material during the forming process. While exceeding the load limits, a failure in the component material occurs, which can be avoided by additional force transmission activated in the deep drawing process before the forming limit of material is achieved. This contribution deals with numerical investigation for process effect of additional force transmission concerning the extension of the forming limits. Here, the steel material H340LA is analysed numerically relating to two different part geometries, rotational symmetric part and cap profile. Both, the FEA of conventional and forming process with additional force transmission are carried out. The estimated result of additional force transmission effect is used for comparison with the numerical results of conventional deep drawing process.
Production of multi-rifled seamless steel tubes in Železiarne Podbrezová is quite a new technology. Therefore, a lot of technological questions emerges (process technology, input feedstock dimensions, material flow during drawing, etc.) Pilot experiments to fine tune the process cost a lot of time and energy. For this, numerical simulation would be an alternative solution for achieving optimal parameters in production technology. This would reduce the number of experiments needed, lowering the overall costs of development. However, to claim the numerical results to be relevant it is necessary to verify them against the actual plant trials. Searching for optimal input feedstock dimension for drawing of multi-rifled tube with dimensions Ø28.6 mm × 6.3 mm is what makes the main topic of this paper. As a secondary task, effective position of the plug – die couple has been solved via numerical simulation. Comparing the calculated results with actual numbers from plant trials a good agreement was observed.
The metal or steel content in a used tire, originally incorporated to improved tire properties (resistance, adherence ...) was recovered by cryogeic-grinding process. The tire has been precooled with liquid nitrogen for ten minutes and then ground with cryogenic grinding process, where we obtained a mixture of steel and ultra-fine powder tire. We subsequently recovered steel or metal mixed with ultra-fine powder of the tire, after cryogenic grinding process by magnetic separation steel recovered by cryogenic grinding of used tires were characterised by optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction analysis (XRD).
This paper provides a study of carbide dissolution during heating of bearing steel using computational thermodynamics and kinetics. 100Cr6 steel was used for the experimental work and calculations using the Thermo-Calc and Dictra. Carbide dissolution was calculated at different fully and partially austenization temperatures from 840 to 1200 C. The calculations also give the distribution of the alloying elements at carbide and austenite phase boundaries. In experimental work, LM and SEM were used to study microstructures. SEM micrographs were evaluated with line intercept technique and carbide size and quantity were determined. The experimental results were compared with calculations providing good correlation.