Werkstoffkennwerte für die Lebensdauerberechnung von Strukturen aus Stahlfeinblechen für den Automobilbau

Materials Data for Fatigue Life Calculation of Steel Sheet Structures for Automotive Engineering Within a joint project of the steel and automotive industry 17 steel sheet materials for automotive engineering in various delivery and forming conditions at temperatures of –40 °C, 22 °C and 100 °C were investigated. In the course of 37 test series strain controlled fatigue curves to crack initiation and stress‐strain‐curves under monotonic and cyclic loading were determined. All experimental data, hysteresis loops and determined cyclic properties are available in a database. A correlation between the mechanical properties from tensile tests and the properties from strain controlled cyclic experiments seems to be possible.     

Effect of friction coefficient change on internally shaped tubes drawing process using finite elements method

Presented article is focused on the effect of friction coefficient of drawing mandrel surface on parameters of the drawing process. Drawing of tubes with the internally shaped surface is complex problematics. Creation of internal ribbing is determined by many deformation zones which affect stress and strain acting in forming process. Finite elements method application on solving presented problematics gives the opportunity to simulate and optimize process without expensive prototype mandrels. Research if mainly focused on the shape and properties of drawing mandrel. For simulations purposes were selected three friction coefficients which are common in drawing process in dependence of tool surface and coating in combination with lubrication. Acquired results show behavior of strains and stresses in drawing process. Maximal values of observed parameters accompanied with jump changes are mostly pronounced in inner layer. Obtained values are applicable for setting of lubrication in drawing process from the perspective of elimination jump changes in stresses which can shorten life time of mandrel and lower quality of final product.