An eulerian finite-element model for determination of deformation state of a copper subjected to orthogonal cutting
- PDF / 773,215 Bytes
- 8 Pages / 612 x 786 pts Page_size
- 47 Downloads / 156 Views
9/27/04
9:09 PM
Page 2393
An Eulerian Finite-Element Model for Determination of Deformation State of a Copper Subjected to Orthogonal Cutting A. RACZY, M. ELMADAGLI, W.J. ALTENHOF, and A.T. ALPAS An Eulerian finite-element (FE) model was developed to predict the stress and strain distributions in the material subjected to the orthogonal machining process. Metallographic sections taken from commercially pure copper samples and subjected to orthogonal cutting were examined to determine the local strain gradients generated in the material ahead of the cutting tool tip. Local flow stress values were estimated from the microhardness measurements. Experimental flow stress and equivalent plastic strain values were found to obey a Voce-type exponential relationship, which was used in the development of the material model for the numerical simulations. The sizes of both the primary deformation zone (350 m) and the secondary deformation zone (50 m) predicted by the numerical model were in agreement with the experimental observations. The experimental results showed that the equivalent strain was 3.65 in the material 50 m directly ahead of the tool tip, which compared well with the numerically observed strain (3.50). According to the numerical observations, along the primary shear plane, the high tool tip stress of 410 MPa decreased to 260 MPa near the chip root. Numerical and experimental stress and strain distributions correlated well in terms of both magnitudes and distributions, indicating that the application of an Eulerian FE approach served to predict the deformation state of the material ahead of the tool tip successfully.
I. INTRODUCTION
DETERMINATION of stress and strain distributions within the workpiece ahead of the tool tip during the machining process has been the subject of several research studies, both from experimental and numerical viewpoints. The associated plastic deformation zones, namely, the primary deformation zone (PDZ) within the workpiece ahead of the tool tip and the secondary deformation zone (SDZ) adjacent to the rake face, are illustrated in Figure 1. One of the first theories of deformation geometry of the workpiece was developed by Piispanen[1] and Merchant,[2] which assumed deformation occurred along a single shear plane producing a “stack of cards” type geometry behavior during chip formation. Merchant[3] derived the location of this plane by the principle of minimization of plastic deformation work. Recht[4] and Okushima and Hitomi[5] expanded the concept of deformation along a single shear plane to incorporate a plastic deformation zone with a finite thickness in the material ahead of the tool tip. A more complete depiction of the material behavior during machining that considered a dynamic equilibrium between work hardening and the recovery process was proposed by von Turkovich.[6] Detailed experimental work of Lemaire and Backofen[7] and Ramalingam and Black[8] are among the first that investigated the role of microstructure on machinability. In parallel with the experimental st
Data Loading...
