Browsing by Author "Pasupuleti, Shashank"

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    A Comprehensive Data Set of CFRP Impact Damage Accumulation Through a Novel Impact Experimental Setup
    (2021-08-25) Pasupuleti, Shashank; Brake, Matthew
    In the following work, a low-velocity impact pendulum inspired by the Charpy and Izod testing impact pendulum was designed and manufactured to examine the in-plane strain response of IM7/8552-1 carbon fiber/epoxy composite specimens under the CFCF plate condition. The pendulum itself covers an impact energy range similar to the Charpy and Izod low-velocity impact testing setup, yet allow the pendulum to be applied to extended Tribology and Fracture Mechanics studies without a notched sample. Tensile tests were performed on six 16-ply composite samples to characterize the IM7/8552-1 composite within a comprehensive data set and to ensure that DIC as a non-contact strain measurement tool would suffice for impact testing. Impact tests were also performed at four different swing angles associated with four different impact energies. At each impact level, three 16-ply 2” x 1” samples per layup configuration were repeatedly struck at the same swing angle until the samples failed. In-plane strain plots of each impact sample’s rear surface were compiled for each sample through DIC in each direction: the longitudinal (x) direction parallel to the composite’s 0° fibers, the lateral (y) direction perpendicular to those fibers, and the shear strain associate with this plane. The results from the strain plots and collected force vs. time plots were utilized to investigate a critical impact energy, the discrepancy between the number of hits to failure each composite stacking sequence can endure, and patterns in the residual strain with each isolated hit at these distinct impact energies. These determinations are made to contribute to properly characterize composites in the framework of damage tolerance philosophy and “slow-growth” to enhance current composite damage modeling efforts in the pursuit of fatigue after impact.