A novel approach to accelerate attainment of thermal steady state in coupled thermomechanical analysis of machining

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Authors
Deshpande, Amit Anand
Madhavan, Viswanathan
Advisors
Issue Date
2012-06
Type
Article
Keywords
Finite elements , Coupled thermomechanical analysis , Machining , Steady state , Specific heat , Thermal Inertia , Tool wear , Thermal waves
Research Projects
Organizational Units
Journal Issue
Citation
Deshpande, Amit Anand & Viswanathan, Madhavan. 2012. “A novel approach to accelerate attainment of thermal steady state in coupled thermomechanical analysis of machining”. International Journal of Heat and Mass Transfer, Volume 55, Issues 13–14, June 2012, Pages 3869–3884
Abstract

A novel approach for obtaining the steady state temperature distribution of cutting tools involves reducing the specific heat capacity of the cutting tool by a scale factor and carrying out a short duration single step thermomechanical analysis. Reduction of the specific heat causes the thermal time constant of the tool to be reduced by the same scale factor, making it closer to the mechanical time constant required for stabilization of the chip geometry, and enables rapid attainment of mechanical and thermal steady state conditions. As expected, FEA results show that the steady state temperature distribution achieved by the reduced specific heat approach is exact. Results obtained from a single step simulation of the first 1200 μs of cutting, using this approach, are found to be more accurate than those obtained using the time consuming multistep analysis approach used to date. Rapid attainment of an accurate steady state temperature distribution permits tool wear rate to be calculated accurately using tool wear models. This enables tracking of changes in tool geometry due to wear over time, and resulting changes in the machining process and part quality produced. It is also shown that this approach is essential for accurate simulation of processes such as saw-tooth chip formation, where the ‘steady state’ involves local periodic thermomechanical changes, and leads to accurate thermomechanical results so long as the specific heat of the local region experiencing significant thermal oscillations is not scaled. An estimate for the size of this boundary layer, related to the wavelength of the thermal waves, is also given. The reduced specific heat approach can be used in many other applications involving a range of phenomena coupled with temperature, where the thermal changes are the most sluggish and take the most time to reach steady state.

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Publisher
Elsevier
Journal
Book Title
Series
International Journal of Heat and Mass Transfer;2012, v.55, issues 13-14
PubMed ID
DOI
ISSN
0017-9310
EISSN