Abstract
Sandwich panels with composite laminate skins having [(±45C)2,(0C,0G)4,(±45C)2] stacking sequence (subscript C for carbon fibers, G for glass) and containing barely visible impact damage (BVID) induced on the whole sandwich structure impacted at low energy, were tested in edge after-impact-compression with load direction parallel and transversal to the fibers direction (0-dir.). The morphology of impact damage on the sandwich structure was determined by using ultrasonic C-Scan and visual observation of laminate cross section. A Digital Image Correlation (DIC) system was used to measure the delamination evolution during the test. Two different failure behaviors were observed in two different impacted panels. Panel with fibers oriented transversally to the compressive load showed an opening (Mode-I) propagation of a delamination, while the panel with fibers parallel to the load showed shear (Mode-II) propagation. The static load such to determine local buckling of the composite face and failure was experimentally measured. An analytical model was implemented to predict the static strength of laminate with Mode-I opening. An FE model was instead built to predict the local buckling failure mode of the laminate with BVID, which is the first phenomenon to appear. The results of the analytical model and the numerical simulation correlate well with the test.
Highlights
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As aresubject subjecttoto impact in many applications during their life, many researchers in the last decades have investigated the influence of impact damage service life, many researchers in the last decades have investigated the influence of impact damage on static and fatigue strength and studied the damage mechanism of these structures
Time consuming in the preprocessing phase and a non-negligible margin of error exists. It model is time consuming in the preprocessing phase and a non-negligible margin of error is recommended to use the analytical model which has an error of compared exists
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in Materials. The authors of [11,12,13,14,15,16] experimentally investigated the compressive strength of impacted sandwich panels They claim that the residual strength is 40% of the Materials 2021, 14, 5553. Kassapoglou et al [17] developed an analytical model to predict compressive buckling of sandwich panels with elliptical cracks (delamination) in the area creativecommons.org/licenses/by/. They claim that the residual strength is 40% of the undamaged specimens. Kassapoglou et al [17] developed an analytical model to predict compressive buckling of sandwich panels with elliptical cracks (delamination) in the area of the interface composite/core. The FE model was developed to predict local buckling, which is the first failure mode observed in the tests
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