Identification of heat source fields from infrared thermography: Determination of ‘self-heating’ in a dual-phase steel by using a dog bone sample

Abstract

a b s t r a c tFrom infrared thermography, a quantitative analysis of heat dissipation sources is proposed via the thermomechanical modeling of a fatigue test on a specimen with a varying cross-section. A new procedure is introduced to achieve this goal, and its application to an experimental case of self-heating at a single load level is shown to provide complete identification of a probabilistic model of micro-plasticity.

Thermographic Method Based Accelerated Fatigue Limit Calculation for Steel X5CrNi18-10 Subjected to Rotating Bending

“…Since the specimen or the structural element subjected to static load [11][12] [13] or dynamic load is a source of heat generated as a result of internal processes, mainly those related with plastic deformation [14] [15] [16], then the methods which base on specimen temperature measurements, in particular contactless thermographic methods, are very useful for modelling the fatigue process [17].…”

Digital image correlation and infrared measurements to determine the influence of a uniaxial pre-strain on fatigue properties of a dual phase steel.

“…For a 1D thermal diffusion problem, the local heat equation conduction is written as [10] ρCθ(x, t) − λ ′ ∂ 2 θ(x, t)…”

“…Due to the noise of the thermal signal and the regularizing effect of heat diffusion, the reconstruction of heat source maps is still a difficult task. In this paper, to handle the inverse problem, 37007-p. 5 the theoretical result of the heat source is used to build a theoretical temperature field from a particular basis proposed by [10]. In this case, the identification of the heat source consists in minimizing the difference between the calculated temperature and the experimental one.…”

“…with a, b, c parameters that have to be identified and θ ′ ak and θ ′ bk functions of the components of the Fourier basis [10]. To include the influence of a plastic pre-strain, the modification of the intensity of the process, that drives the scenario of microplasticity appearance, leads to consider a thermal source…”

POD Preprocessing of IR Thermal Data to Assess Heat Source Distributions

“…For uniaxial tests performed on thin flat samples, a first possibility is to work with a diffusion equation integrated over the specimen cross-section [14]. The specimen gage length is denoted by L. With ϑ(x, t) now denoting the mean temperature variation at time t over the cross section S(x), and x being the longitudinal coordinate, the 1D heat diffusion equation can be formulated as:…”