Quantification of Flaws in Fibered Composite Structures Using Interferometric Fringe Patterns
ARMY MISSILE RESEARCH DEVELOPMENT AND ENGINEERING LAB REDSTONE ARSENAL AL GROUND EQUIPMENT/MATERIALS DIRECTORATE
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This study concerns the nondestructive detection and quantification of flaws and voids in thin, cylindrical, fiber reinforced, composite, structures. Three different types of flaws were investigated using real-time and double exposure optical holography, and Youngs Fringe method of speckle interferometry. The theory for each technique and photographs of the fringe patterns are presented. The fringe density plots were made by both manual and computer methods and the flaw sizes were determined. The displacements and strains were computed. A computer program using conventional finite elements was used to theoretically compute the displacements near the border of the flaws. A new crack tip element was suggested to improve the results in the region of the flaw border. The results show that flaws in their fiber reinforced composite structures can be detected and the size determined by either optical holographic or speckle interferometric techniques.
- Laminates and Composite Materials
- Test Facilities, Equipment and Methods
- Rocket Engines