Quantitative Analysis of Impact Damaged Composite Tension-Torsion Specimens Using Laser Speckle Interferometry.
ARMY MISSILE COMMAND REDSTONE ARSENAL AL GROUND EQUIPMENT AND MISSILE STRUCTURES DIRECTORATE
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Test specimens in the form of standard tensile coupons were fabricated from XP250 composite laminate material manufactured by the 3M Company. A series of six different wrap angles, measured from and symmetric to the longitudinal specimen axis was used. At each wrap angle eight specimens were fabricated with flaws due to dynamic impact loading. Five unflawed specimens were also fabricated for comparison purposes. Each of the flawed specimens and one unflawed specimen at each wrap angle were individually placed in an apparatus for generating low load level tension and torsion. Laser speckle interferograms of the specimens were made and analyzed. The ratio of the strain in the flawed region of each specimen was compared to the unflawed specimens at each wrap angle using laser speckle interferometry. These results were correlated with the ultimate strength of each specimen obtained in a simple tension test using an Instron machine. Comparison of results was favorable. Author
- Laminates and Composite Materials