ABSTRACT of the Doctoral Thesis
To be able to simulate the cutting process one first has to characterise the mechanical properties of the materials of interest. At least those properties have to be characterised, which are important for the cutting process: the materials plasticity and damage behaviour.
To determine the flow curves that describe the plastic properties of the materials considered in this work, mainly tensile tests on flat samples and combined rolling- and tensile test experiments are done.
For the determination of the damage behaviour besides micro-tensile tests on cylindrical specimens also microscopic investigations are carried out.
To be able to check for correspondence between experimental and numerical results the punching force as it evolves during the cutting process is recorded which can afterwards be compared to the numerical results. Also the geometry of the cutting edge, from the experiments and the simulation are compared. To be able to do this in a more quantitative way, the cut edges from micro photographs, showing the experimental result and the field plots showing the cut edge out of the simulation are described through so called cut edge parameters. To define these parameters, the cut edge is subdivided into certain regions which can be characterised through measuring their vertical or horizontal length and their vertical or horizontal angle (with respect to the undeformed top of the cut sheet). The correspondence between experimental and numerical results is found to be acceptable.
As this work is part of an ECSC-project dealing with the corrosion of cut edges of organic coated sheets, also corrosion tests and the measurement of the degree of delamination at the cut edges are of interest. The investigations shall show whether there is a connection between the geometry of the cut edge and the degree of delamination as is found after the corrosion test in the region of the cut edge. This question could not be clarified satisfactorily because of experimental limitations.
As further examples of application of the FE-Methode in the fields of the cutting process, three dimensional calculations, one assisting the design of an inline cutting tool and the other concerning investigations on the trimming of coils, are carried out.
Also tools for computer assisted measurement and image processing are developed. One tool assists the measurement of the cut edge namely the determination of the cut edge parameters and the other one is a fully automatic image processing tool for measuring the degree of delamination in the region of the cut edge. The latter has been developed further into a commercial product called SMART which stands for Surface Multianalyses and Reporting Tool.