Stress analysis photoelastic method

This photoelastic stress analysis is a technique for the nondestructive determination of stress and strain components at any point in a stressed product by viewing a transparent plastic product. If not transparent, a plastic coating is used such as certain epoxy, polycarbonate, or acrylic plastics. This test method measures residual strains using an automated electro-optical system. 

The indirect analytical nondestructive evaluation methods of interest are thermal analysis, finite element stress analysis, strain gauging, photoelasticity and brittle coatings. 

Other methods available for nondestructive evaluations are indirect in nature, but may be useful in certain situations. These methods will only be discussed in a cursory fashion and more detailed aspects can be obtained from the literature. It is useful to note that stress in any structure plays a vital role, and that the methods involved in determining stress in an engineering component or structure in the process conditions is of vital importance. The methods used in determining stress are finite element stress analysis, strain gaging, the photoelastic method and brittle coatings. 

Photoelastic stress analysis helps a processor determine why a part broke and how to prevent similar failures in the future. Parts ranging in size from structural composites to tiny thermoplastic heart valves can all be tested easily. The test method is also a valuable tool for predicting where prototype parts may fail, such as in poorly designed features... 

The photoelastic method for experimental stress analysis is very popular among design engineers and failure analysts and has proved to be an extremely versatile, yet simple, technique. 

Photoelastic analysis, one of several related testing techniques, is easy to use and usually a more economical and positive method than computer analysis. From the information it provides, the test can lead to better-designed, lower-cost products. Traditionally used to test the integrity of metal parts, photoelastic analysis is now being used to physically test thermoplastics as well as thermosets. For transparent plastics, the analysis can be made directly on the plastic. For nontransparent plastics, a transparent coating is used. Actual parts and representative models can be tested by a simple procedure. The former may be stressed under actual use conditions, whereas models are tested under simulated conditions. 

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