Numerical and experimental investigation of Johnson–Cook material models for aluminum (Al 6061-T6) alloy using orthogonal machining approach

Sohail Akram,Syed Husain Imran Jaffery,Muhammad Fahad,Liaqat Ali,Mushtaq Khan,Aamir Mubashar

doi:10.1177/1687814018797794

Abstract

This research focuses on the study of the effects of processing conditions on the Johnson–Cook material model parameters for orthogonal machining of aluminum (Al 6061-T6) alloy. Two sets of parameters of Johnson–Cook material model describing material behavior of Al 6061-T6 were investigated by comparing cutting forces and chip morphology. A two-dimensional finite element model was developed and validated with the experimental results published literature. Cutting tests were conducted at low-, medium-, and high-speed cutting speeds. Chip formation and cutting forces were compared with the numerical model. A novel technique of cutting force measurement using power meter was also validated. It was found that the cutting forces decrease at higher cutting speeds as compared to the low and medium cutting speeds. The poor prediction of cutting forces by Johnson–Cook model at higher cutting speeds and feed rates showed the existence of a material behavior that does not exist at lower or medium cutting speeds. Two factors were considered responsible for the change in cutting forces at higher cutting speeds: change in coefficient of friction and thermal softening. The results obtained through numerical investigations after incorporated changes in coefficient of friction showed a good agreement with the experimental results.

Highlights

Modeling of material processing and in-service performance of materials pose great difficulty while analyzing high material deformation rate of structural materials.[1]
orthogonal tube turning (OTT) was reported to have a high degree of accuracy in terms of acquiring force data, as the effects of centrifugal forces, chip curling, and surface velocity are negligible in this experimental setup.[8]
All experiments were conducted on ML-300 Computer Numerical Control (CNC) Turning Machine manufactured by YIDA Precision Machinery Company, Taiwan

Summary

Introduction

Modeling of material processing and in-service performance of materials pose great difficulty while analyzing high material deformation rate of structural materials.[1]. Advances in Mechanical Engineering arises due to large strains, strain rates, and adiabatic conditions These conditions result in increased temperature and associated changes in material properties, microstructure, and deformation processes.[1] understanding of complex deformation mechanisms and failure responses requires development of accurate constitutive material models which can reliably describe the thermo-mechanical behavior.[2]. OTT was reported to have a high degree of accuracy (over 99%) in terms of acquiring force data, as the effects of centrifugal forces, chip curling, and surface velocity are negligible in this experimental setup.[8] OTT has the advantage of being highly flexible and adjustable on shop floor.[7] This method has been widely used by the previous researchers and can effectively model the orthogonal machining setup used in the simulations presented in this article. FEM predictions showed good overall agreement with the experimental results for selected machining conditions

Experimental setup

À sin a

Methodology validation

Discussion

Findings

Conclusion