Stress Analysis of Holes in Thick Plates

Emery

Quinn

et al. 2006

Meas. Sci. Technol.

In thermoelastic stress analysis, an infrared detector is used to obtain the small temperature change resulting from the thermoelastic effect. The output from the detector, known as the thermoelastic signal, is dependent on both the surface stresses and the surface temperature of the component under investigation. For quantitative thermoelastic stress analysis, it is important that the response resulting from changes in the surface temperature is decoupled from the response resulting from the stress changes. In this paper, a means of decoupling the response is presented that involves making corrections for increases in surface temperature so that the thermoelastic signal is dependent only on the stresses. The underlying theory is presented and a correction factor is developed using an experimental approach. A methodology for applying the correction factor to full-field data is provided. The methodology is validated through a number of case studies and applied to a composite component subject to fatigue damage initiated at a central hole.

Section: S = F (σ )(T )mentioning

confidence: 99%

Section: Theoretical Basismentioning

confidence: 99%

A temperature correction methodology for quantitative thermoelastic stress analysis and damage assessment

Emery

Quinn

et al. 2006

Meas. Sci. Technol.

“…Some unpublished work based on experimental data provided in Ref. [6] has indicated that equation ( 8) is valid. However, a means of experimental validation was required, hence the motivation for this work.…”

Section: Experimental Approachmentioning

confidence: 99%

“…However, the effect was minimal and often within the noise of the experimental data and thus was largely ignored. It has been noted that the thermoelastic signal from the Deltatherm system varies significantly with temperature [6] and could not be compensated for by the application of equation ( 3). This is due to the differences in detector material and operating wavelength.…”

Section: Introductionmentioning

confidence: 99%

Development of a Temperature Calibration Device for Thermoelastic Stress Analysis

Quinn

Eyre³

et al. 2004

AMM

“…The 74°C increase in temperature caused by the localised heating above far exceeds that caused by the effect of viscoelastic heating alone; in Ref [4] this was reported to result in a temperature change of the order of 30°C for an epoxy based composite. The considerable heating experienced in either case would significantly affect the thermoelastic data [5,6] as reported by previous studies, therefore a means of correcting for this increase is necessary.…”

mentioning

confidence: 92%

Identification of Damage in Composite Structures Using Thermoelastic Stress Analysis

Emery

Cunningham

2005

KEM

The application of a cyclic load on a composite material containing damage has the effect of heating due to the material viscoelasticity. This is exaggerated in the proximity of interlaminar failure because of friction between plies. Quantitatively studying a stressed component subject to these conditions using Thermoelastic Stress Analysis (TSA) has been inaccurate, as the localised heating has an effect on the thermoelastic response. Hence the thermoelastic signal from damaging composites will contain a stress-induced component and a temperature-induced component. In this paper a process is described that allows the thermoelastic signal to be de-coupled into a stress component and a temperature component. This is achieved using a combination of infra-red thermography and TSA. The process is based on the use of a special calibration device. The paper provides an experimental verification of the de-coupling using actual damaged composite components.