This paper presents an experimental investigation of a new method for damage detection based on the most fundamental concept in continuum mechanics: strain compatibility. Compliance with this principle implies a deformed material is free from discontinuities, which are indicative of many types of structural damage. Therefore the principle of strain compatibility, in its ability to identify discontinuities, is very promising as a new foundation for future research into non-destructive evaluation and structural health monitoring technologies. The proposed method has many advantages compared to existing damage detection techniques, such as its invariance to material properties, type and intensity of loading, and the geometry of the structure. In this paper, a proposed formulation of the strain compatibility equation for beam structures, which is invariant to loading intensity, is presented. An experimental investigation of the proposed algorithm was conducted on a delaminated cantilever beam, utilising a PSV-3D scanning laser vibrometer. The experiment demonstrated that the strain compatibility technique can accurately locate delamination damage in composite beam structures.