The application of infrared thermography to the measurement of transient temperature fields generated by
fusion welding of ship structures is described. The purpose is to capture real data from practical welding
situations, which can then be used as input to computational simulation of welding manufacturing
operations (virtual fabrication). Workpiece distortion due to thermal mismatch strains constitutes a major
technological and economic problem in welding fabrication, and there is worldwide research interest in
simulation techniques that facilitate off-line investigation of methods to reduce distortion in real
applications. The effectiveness of such methods depends critically on the thermal input stage, where the
complex effects of variable arc energy transfer, non-linear material properties, and workpiece / fixture
heat-sink variables are present in a practical case. Thermography provides a unique method to measure
such parameters on a whole-field basis.
The paper presents measurement comparisons made on large welded plate structural components
between whole-field thermographic data, thermocouple data, finite-element thermal analysis, and
analytical approaches. The paper also addresses relevant thermal imagery problems in this context, such
as emissivity calibration and compensation methods for lens distortion. Thermography is shown to be an
ideal way to identify the outcomes of practical features such as thermal discontinuities in the workpiece
and the effects of weld preparation and process variables on the thermal transfer efficiency of the welding
process electrical energy.peer-reviewe
