FE-simulation of machining processes with a new material model

• Published in: Journal of materials processing technology 2014-03, Vol.214 (3), p.599-611
• Main Authors: Buchkremer, S., Wu, B., Lung, D., Münstermann, S., Klocke, F., Bleck, W.
• Format: Article
• Language: English
• Subjects: AISI 1045; Chip formation; Chips; Computer simulation; Cutting; Cutting simulation; Damage; Extended MBW model; Iron; Material model; Mathematical models; Medium carbon steels; State of stress; Stresses; Turning
• ISSN: 0924-0136
• DOI: 10.1016/j.jmatprotec.2013.10.014

In the field of materials mechanics the influence of the state of stress on the plastic deformation behavior of metals is known since decades. However, the state-of-stress influences are usually not considered in structural or processing simulations. Nevertheless, its application in the numerical investigation of manufacturing processes seems very promising since, for example, machining processes are characterized by complex states of stress. Consequently, its incorporation in the computation of the workmaterial's flow stress may increase the physical conformity and accuracy of cutting FE-analysis. This paper presents the creation and experimental validation of a 3D-FEM model of the longitudinal turning process with an extended modified Bai–Wierzbicki material model (extended MBW model). This newly developed material model evaluates the influence of state of stress as well as damage on the strain hardening behavior. In addition, it takes temperature and strain rate effects into consideration, whose influences are both typically higher in cutting processes than in structural–mechanical problems. For the validation of the proposed material model, longitudinal turning experiments were conducted on AISI 1045 steel. Four different cutting tools and process conditions were investigated, which cover a broad range from finishing to roughing. A high speed camera was used to film the chip formation and chip flow in order to compare it to the simulation results. The three cutting forces components were also collected. Measured chip temperatures were taken from the literature. The validation showed that the implementation of the selected material model results in a close agreement between experimentally obtained and predicted chip geometries, cutting forces and chip temperatures.