Thermomechanics and Infra-Red Imaging

Challenges in synchronising high speed full-field temperature and strain measurement

ABSTRACT The overall motivation for the research described in the paper is an enhanced understanding of the behaviour of fibre reinforced polymer composites subjected to high velocity loading. In particular, the work described here considers a method that allows the collection of synchronised high speed full-field temperature and strain data to investigate the complex viscoelastic […]

The use of infrared thermography at high frame rates

ABSTRACT Composite materials are finding increased use in applications where impact and high strain rate loading form a significant part of a component’s service loads. It is therefore imperative to fully characterise the thermomechanical response of composite materials at high strain rates. The work described in the paper forms part of a project investigating the […]

In Situ Heat Generation and Strain Localization of Polycrystalline and Nanocrystalline Nickel

ABSTRACT Commercially available polycrystalline nickel (Ni200; grain size: 30 ^m) and electrodeposited nanocrystalline nickel (grain size: 30 nm) were analyzed for the phenomena of in-situ heat generation and strain localization during plastic deformation at room temperature. Tensile specimens according to ASTM E8 standard dimensions were tested at a strain rate of 10-2/s to record the […]

Dissipative and coupling effects accompanying the natural rubber elongation

ABSTRACT Rubber-like materials can undergo very large strains in a quasi-reversible way. This remarkable behavior is often called hyper (or entropic) elasticity. However, the presence of mechanical loops during a load-unload cycle is not consistent with a purely elastic behavior modeling. Using Digital Image Correlation and Infra-Red Thermography, the present study aims at observing and […]

Experimental estimation of the Inelastic Heat Fraction from thermomechanical observations and inverse analysis

Abstract A new method to estimate the inelastic heat fraction (Taylor and Quinney Beta coefficient) during the deformation of a titanium material is proposed. It is based on (1) thermomechanical full field measurements during the loading and on (2) an inverse analysis. First, two cameras (a visible and an infrared) are used to measure the […]

Energy balance properties of steels subjected to high cycle fatigue Part 1

ABSTRACT This paper presents an experimental protocol developed to locally estimate different energy balance terms associated with the high cycle fatigue (HCF) of steels. Deformation and dissipated energy are respectively derived from displacement and temperature fields obtained using digital image correlation (DIC) and quantitative infrared thermography (QIRT) techniques. The combined processing of visible and infrared […]

Energy balance properties of steels subjected to high cycle fatigue Part 2

Thermoelastic response Until crack onset, we observed quasi-uniform patterns of thermoelastic nature as expected for a simple tension-compression test. Besides, the experiments showed that Asthe increased linearly with stress and the load frequency as predicted by a linear thermoelastic law [5]. An example of the distribution of thermoelastic source amplitudes is given in Fig.6. Fig. […]

Contribution of Kinematical and Thermal Full-field Measurements for Identification of High Cycle Fatigue Properties of Steels

ABSTRACT Using kinematical and thermal full-field measurements for identification of mechanical parameters has become a very promising area of experimental mechanics. The purpose of this work is to extend the use of non-conventional tests and full field measurements (kinematical and thermal) to the identification of the fatigue properties of a dual-phase steel. A particular attention […]

Dissipative energy : monitoring microstructural evolutions during mechanical tests

ABSTRACT Fatigue characterization is an expensive operation commonly undertaken in industry. Some authors thus developed experimental measurement methods based on the materials thermomechanical behaviour to provide faster fatigue limit estimations. Yet, the physical ground of these methods needs to be understood. In this work, it has been assumed that heat dissipation phenomena are related to […]

Bidirectional Thermo-Mechanical Properties of Foam Core Materials Using DIC

KEYWORDS: PVC foam, Modified Arcan fixture, Digital image correlation, Thermal degradation, Finite element analysis ABSTRACT Polymer foam cored sandwich structures are often subjected to aggressive service conditions which may include elevated temperatures. A modified Arcan fixture (MAF) has been developed to characterize polymer foam materials with respect to their tensile, compressive, shear and bidirectional mechanical […]

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