Numerical and Experimental Fracture Mechanical Investigations of Clinchable Sheet Metals Made of HCT590X

摘要

Joining is used in many areas of manufacturing, where constructions from individual components or metal sheets are formed into complex structures. A simple and industrial common method for joining dissimilar and coated materials is clinching. Damage caused by the joining process or by the service load can lead to cracks in the vicinity of the joint, to crack propagation because of time-varying loading and subsequently to the entire failure of the technical component. For the prevention of these damage cases, first of all knowledge about the fracture mechanical material parameters regarding the original material state of the sheet metals used within the clinching process are essential. In the context of this paper the fracture mechanical behavior of the raw sheet metals utilized within the clinching process is presented with the help of experimental as well as numerical investigations. Due to the low thickness of 1.5 mm of the metal sheets, it is essential to develop a special specimen in order to determine the crack growth rate curve including the fracture mechanical parameters like the threshold against crack growth AKI,th and the fracture toughness Kic of the base material HCT590X. For the experimental determination of the crack growth rate curve the geometry factor function as well as the calibration function of the special specimen need to be known. These characteristic functions are numerically computed. After the experimental validation of the calibration function, crack growth rate curves are recorded for the stress ratios R = 0.1, R = 0.3 and R = 0.5 to examine the mean stress sensitivity. In addition, for the investigation of the impact of the anisotropy due to rolling the different rolling directions of 0° and 90° in relation to the starting crack are taken into account.