The Versailles Project on Advanced Materials and Standards (VAMAS) is an international collaborative programme which was set up to promote the underpinning research and development that is required to be undertaken as a precursor to the preparation of new standards relevant to advanced materials. It is intended that the programme leads to agreed international collaboration standards which will aid trade world-wide.

Technical Working Areas (TWA) have been identified which cover a range of topics in these fields. TWA20 is concerned with the measurement of residual stress in materials. Between 1996 and 2001 TWA20 dealt with stress measurement by neutron diffraction. This led to the release in 2001 of an ISO TTA 'Polycrystalline materials - Determination of residual stresses by neutron diffraction'.

TWA20 is currently addressing stress measurement by high energy synchrotron X-ray measurement. The main objectives are to:

	Establish accurate and reliable procedures for determining residual stress by synchrotron diffraction.
	Examine a variety of samples in which residual stresses have been introduced by different techniques.
	Conduct inter-laboratory comparisons to establish reproducibility.
	Assemble the necessary information for preparing a standard.