TY - THES

T1 - FE - simulation of chip formation in inhomogeneous materials

AU - Distlberger, Stefan

N1 - embargoed until 17-04-2019

PY - 2014

Y1 - 2014

N2 - The chip formation in today's machining is a complex process that has not been completely understood yet. The process is defined by friction, chip formation, material, cutting force, hole inclusions in the cut material and many more aspects. Correlations between some of these aspects are analyzed in this thesis by using the commercial finite-element software ABAQUS Standard. This thesis presents a survey of today's simulation techniques and ways to facilitate chip formation simulations. A semi automated tool is developed which allows to simulate a 2D chip formation of a homogeneous material or an inhomogeneous material in ABAQUS Standard. The tool automates the remeshing process to avoid severe element distortion. It also automates the time consuming manual process of the modeling itself. The pertaining routines are coded in Python and Fortran. To visualize results, the author provides a further tool for rendering videos as well as utilities for investigating certain aspects of the process, such as the change of the chip's width or the contact forces over time. The influences of three different element sizes are discussed: A decreasing element size results in a decrease of the chip's width, an increased rake angle of the chip and a decrease of the tool's contact force. A homogeneous specimen with decreasing chip thickness is simulated to investigate the decrease of the tool's force and the decrease of the chip's width over time. Two models are compared: The first one shows chip formation with the chip getting in contact with itself. The second model shows chip formation where the chip is trimmed before self contact can occur. Both models show a change in the chip's width and contact length between tool and workpiece. An inhomogeneous model is presented to study the effects of an inclusion moving through the primary deformation zone of the chip. The size of the inclusion and the position are varied. It is confirmed that the size and the position of an inclusion have a great impact on the chip's formation. The results show the formation of a sharp notch in the chip when a large inclusion is positioned near the workpiece's surface.

AB - The chip formation in today's machining is a complex process that has not been completely understood yet. The process is defined by friction, chip formation, material, cutting force, hole inclusions in the cut material and many more aspects. Correlations between some of these aspects are analyzed in this thesis by using the commercial finite-element software ABAQUS Standard. This thesis presents a survey of today's simulation techniques and ways to facilitate chip formation simulations. A semi automated tool is developed which allows to simulate a 2D chip formation of a homogeneous material or an inhomogeneous material in ABAQUS Standard. The tool automates the remeshing process to avoid severe element distortion. It also automates the time consuming manual process of the modeling itself. The pertaining routines are coded in Python and Fortran. To visualize results, the author provides a further tool for rendering videos as well as utilities for investigating certain aspects of the process, such as the change of the chip's width or the contact forces over time. The influences of three different element sizes are discussed: A decreasing element size results in a decrease of the chip's width, an increased rake angle of the chip and a decrease of the tool's contact force. A homogeneous specimen with decreasing chip thickness is simulated to investigate the decrease of the tool's force and the decrease of the chip's width over time. Two models are compared: The first one shows chip formation with the chip getting in contact with itself. The second model shows chip formation where the chip is trimmed before self contact can occur. Both models show a change in the chip's width and contact length between tool and workpiece. An inhomogeneous model is presented to study the effects of an inclusion moving through the primary deformation zone of the chip. The size of the inclusion and the position are varied. It is confirmed that the size and the position of an inclusion have a great impact on the chip's formation. The results show the formation of a sharp notch in the chip when a large inclusion is positioned near the workpiece's surface.

KW - cutting simulation

KW - chip formation

KW - remeshing

KW - severe mesh distortion

KW - cutting of inhomogeneous materials

KW - Simulation des Schneidprozesses

KW - Spanbildung

KW - Remeshing

KW - große Netzverformungen

KW - Zerspanen inhomogener Werkstoffe

M3 - Diploma Thesis

ER -