Non-contact evaluation of stresses and deformation behaviour in pre-cracked dissimilar welded plates

Full field infrared radiometry based on thermoelastic and thermoplastic theory is introduced for the non-contact evaluation of stress and deformation distributions in mechanically dissimilar material systems. A charge-coupled device (CCD) camera is also employed to investigate the crack tip opening displacement (CTOD). The methods are applied to evaluate the case of cracks located in the vicinity of and orientated parallel to an electron beam weld between dissimilar steel plates loaded in uniaxial tension perpendicular to the weld line. The results are in agreement with the current knowledge of stress and deformation behaviour in dissimilar material systems, and show good correlation with finite element analyses of the problem. Thermoplastic analysis proves to be particularly useful in providing a full-field qualitative map of the plastic deformation distribution. For deformations beyond the elastic limit, the CCD camera offers a flexible alternative to the use of clip gauges in CTOD evaluation.