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A specific device for enhanced measurement of mechanical dissipation in specimens subjected to long‐term tensile tests in fatigue
Author(s) -
Delpueyo D.,
Balandraud X.,
Grédiac M.,
Stanciu S.,
Cimpoesu N.
Publication year - 2018
Publication title -
strain
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.477
H-Index - 47
eISSN - 1475-1305
pISSN - 0039-2103
DOI - 10.1111/str.12252
Subject(s) - dissipation , materials science , thermoelastic damping , thermography , ultimate tensile strength , tensile testing , thermal , composite material , structural engineering , infrared , thermodynamics , engineering , optics , physics
Abstract This paper presents a calorimetric approach to the measurement of mechanical dissipation in specimens subjected to cyclic tensile tests. Mechanical dissipation, that is, the heat power produced by the material due to mechanical irreversibility, can potentially be deduced from the temperature changes captured on the specimen surface by infrared thermography. However, a difficulty arises for long‐term cyclic tests: Results are easily skewed by any change in the specimen's environment. The problem is amplified by the fact that mechanical dissipation is in general small compared to the heat sources associated with thermomechanical couplings, making its estimation difficult. The paper proposes a simple procedure to extract a well‐resolved estimation of mechanical dissipation by solving two key points specific to long‐term cyclic tests: (a) the reduction of the parasitic effects associated with changes in the specimen's environment by using a specific device based on two references samples and (b) the choice of relevant thermal data acquisition parameters. A test is performed on a copper‐based shape‐memory alloy whose calorific response comprises three origins of heat sources: thermoelastic coupling, phase transformation, and mechanical irreversibility. The results obtained demonstrate the relevancy of the approach in extracting mechanical dissipation from the thermal response of the specimen subjected to long‐term tensile tests in fatigue.