FATIGUE IN SHEAR BY BENDING OF STRUCTURAL SANDWICH CONSTRUCTIONS
NORTHROP AIRCRAFT INC HAWTHORNE CA
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The Dynamic Test Method was successfully applied for obtaining core fatigue in shear by reversed bending of a double cantilever beam sandwich specimen containing heavy tip-end masses. The testing approach consists of applying forced vibrations at resonant frequency with an electromagnetic shaker for each stress level desired. Reliable and reproducible S-N fatigue curves were produced on adhesive-bonded aluminum alloy and brazed stainless steel specimens containing representative shear test areas. The uniformity of the core cell geometry and quality of the interface bond were found to have a significant effect on the fatigue life of the sandwich construction. Problems associated with specimen support, shear and bending stresses, symmetrical balancing, stress concentrations, and transmissibility response were overcome through refinement of specimen configuration and test procedure.
- Structural Engineering and Building Technology