SOLUTION SHEET

ThermoESA System

Thermoelastic Stress Analysis (TSA) sensor for advanced,
stress visualisation in materials testing

Thermoelastic stress response
image of an aluminium coupon
with cut-outs

Industrial, in-situ measurement of stress in metallic & composite
components
Thermoelastic Stress Analysis (TSA) is an imaging technique which provides
high-fidelity measurements of stress in objects under cyclic, elastic loading.
TSA employs an infrared imaging sensor with an advanced image processing
algorithm to convert thermo-elastically induced temperature changes into an
image of surface stress.
The technique has a long history of successful use in Aerospace Testing,particularly in identifying and quantifying stress concentrations in metallic
and composite structure with geometrically complex & safety-critical features.

Thermoelastic stress response image of a strut joint under compression, attached to a truss member
under tension

Key benefits
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In-situ (during testing) measurement & processing
Optical, full-field measurement technique
Minor (or even no) surface preparation
Easy finite element model (FEM) validation
Simple operation: point, focus, and measure
Uses an uncooled LWIR (Long Wave Infrared) camera with <1 mK resolved
sensitivity

Thermoelastic stress response
image of a 3D-printed geodesic
truss under torsional loading

High-fidelity imaging that gets better over time
One of the key advantages of TSA, specifically in the application of materials
testing, is the techniques intrinsically high thermal sensitivity that isdependent on two key factors; the material properties of the inspected
object and the time spent observing it.
As such, TSA provides in-situ (semi real-time) measurements of (progressivelyimproving) stress images. Given longer observation times, image noise canbe reduced to a point where stress imagery can resemble an FE simulation invisual quality.

Thermoelastic stress response imageof aluminium sample in a 3-point
bending test

An aluminium coupon sample is tested within the elastic regime under cyclic (fatigue) loading. The
left-side is the FEM model and the right-side is the measurement result at different time intervals
using TSA

An optical, point, shoot & measure experimental measurementtechnique
TSA is an optical, non-contact measurement technique meaning it requires
no mechanical connection to the test object surface. A measurement canbe performed over the entire optically visible surface, yielding full-fieldresults. The MiTE software suite enables users to fuse stress and visualchannels for improved, detailed insight and analysis.
More importantly users do not need to calibrate the sensor and provided
the surface is non-reflective (with high emissivity), the surface does notneed to be prepared before inspection. Simply point, shoot, and measure!

Quick & reliable FEM validation
The thermoelastic effect produces a change in surface temperature that is
directly proportional to change in stress.
Stress visualization of elastically loaded objects allow FEM models to be
rapidly tested, refined and validated
The technique can be applied to structural features of almost arbitrarycomplexity, as such, model validation can be undertaken more rigorously
than with other experimental measurement methods.
The ThermoESA sensor can produce stress images that can be easily
mistaken for a FEM numerical simulation, but without all the uncertainty.

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Thermoelastic stress response imageof a spanner under a cyclic bending
load, acquired in just minutes

Ground-breaking thermal sensitivity of less than 1 millikelvin
The innovative concept behind the ThermoESA stems from the use of acompact, rugged, and “uncooled” LWIR (Long Wave Infrared) camera.
Together with sophisticated signal processing and custom-built timing
electronics, the ThermoESA can achieve a ground-breaking thermal
sensitivity of less than 1 mK (millikelvin). Through using the correlation“lock-in” technique, the ThermoESA has the ability to generate highsignal-to-noise (SNR) images.
Cooled” detectors, which have higher sensitivity compared to “uncooled”
detectors, have very good signal-to-noise (SNR) properties at the start ofa cyclic measurement. However, the SNR does not improve at the samerate as for an “uncooled” detector allowing the ThermoESA to achieve
exceptionally high image quality.

Front & rear side of theThermoESA sensor

MiTE Suite showing the thermoelastic response of a 3D printed truss structure

A compact, industrial tool with a powerful software
Packaged with the ThermoESA system is the powerful MiTE Suite software
package, offering a comprehensive set of tools for advanced stressimaging and analysis.
The software delivers a range of features, including: full complex-valued
thermoelastic response, real-time display of visual and infrared image,semi real-time display (user selectable update rate) of the thermoelastic
response, plotting functions, point and RoI metrics, and stress, strain &temperature change calibration.
The ThermoESA is a complete & fully equipped TSA system supplied
as one sensor with cables, thus making setup quick and easy. Allcomponents (apart from a Laptop PC) are supplied within one, heavy-dutytransport case for rugged protection on-the-go.
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Side images of the ThermoESAsensor

Technical specifications

Order information

Solution Sheet SS_0846_v1. Subject to change without notice. Copyright © 2024.
Dantec Dynamics. All Rights Reserved. www.dantecdynamics.com