A new interferomemtric method of two-dimensional stress analysis

An interformetric method of obtaining the two principal stresses separately in two-dimensional stress distribution is described. An analytical interpretation is given of the relation between the stress-strain state of a transparent elastic plate and the light intensity of the plate observed through the Mach-Zehnder interferometer. The isopachic fringes which give the distribution of the sum of the principal stressesσ1 +σ2 are modulated by simultaneous appearance of the isochromatic fringes which related to the distribution of the difference of principal stressesσ1 -σ2. Accordingly, a single pattern obtained by this method provides sufficient information for evaluating the two principal stresses separately.As examples, a few two-dimensional cases are treated and some practical procedures for carrying out the experiment are described. The feasibility of this method for the general three-diensions frozen-stress model is also discussed.