TWA 26 was established in the late 1990s by VAMAS.

The aim is to bring together those concerned with the use of optical techniques for full field measurements of stress and strain in order to develop internationally accepted standards.

The scope of the TWA embraces all techniques for optically evaluating strain fields including:

• Photoelasticity
• Moiré method
• Laser speckle and interferometry methods
• Image correlation
• Thermoelastic methods

Integration with FE methods for the purpose of validating numerical analyses will form an additional part of the work of this TWA.

A draft pre-standard has been developed by a European consortium, SPOTS and reviewed by members of TWA 26. It is being passed to VAMAS for approval and submission to ISO for publication as a TTA.