Thermal distribution and stress analysis by infrared thermography
While a coupon with a hole is cyclically loaded in the tensile machine, a thermal camera records its surface temperature. The thermoelastic temperature change is computed from the image sequence synchronised with the load signal; regions of stress concentration are marked on the map and compared with the limit.
Amplitude and phase maps are written to the research record together with the load data; a region above the limit is reported with its coordinates and the display shows the load and temperature signals together.
- 01 Clamping
- 02 Cycling
- 03 Sync
- 04 Analysis
- 05 Report
The coupon is clamped; the thermal camera is focused on the gauge region.
- Temperature amplitude
- —
- Load amplitude
- —
- Cycles
- —
Scenes are illustrative simulations; they are not customer references or performance guarantees.
Need
The thermoelastic temperature change is a few thousandths of a degree; ambient light, reflections and the self-heating of the coupon bury this signal. Without locking to the load signal, stress cannot be read from a single image.
Solution approach
The coupon surface is coated matt with high emissivity; the thermal camera looks at the gauge region from a tripod at the side. The machine applies cycles at a fixed frequency and the camera records in sync with the load signal. Averaging locked to the load frequency separates the temperature amplitude from noise; the amplitude is proportional to the stress sum and the map shows the concentration.
Process steps
- 01
Clamping
The coupon is clamped; the thermal camera is focused on the gauge region.
- 02
Cycling
The machine applies a cyclic load at a fixed frequency.
- 03
Sync
Thermal images are recorded in sync with the load signal.
- 04
Analysis
Averaging locked to the load frequency extracts the temperature amplitude; the map builds up.
- 05
Report
The amplitude is compared with the limit; marked regions are written to the record.
Related applications
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