Bending behavior of sandwich structures with different fiber facing types and extremely low-density foam cores

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Uzay Ç. , Geren N. , Bortepe M. H. , Bayramoğlu M.

MATERIALS TESTING, vol.61, pp.220-230, 2019 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Volume: 61
  • Publication Date: 2019
  • Doi Number: 10.3139/120.111311
  • Title of Journal : MATERIALS TESTING
  • Page Numbers: pp.220-230


Sandwich structures offer innovative alternative solutions to many weight-critical industrial fields due to their lightweight and very high flexural rigidity compared to conventional materials. A vast number of sandwich configurations can be produced from a variety of materials for use as face sheets and core as well as matrix. Although there are many sandwich structures available in the literature to obtain the desired mechanical and physical properties, the usage of very low-density core materials is very limited. In this study, carbon and glass fiber fabrics having woven plain and +/- 45 degrees fiber orientations and industrial PVC foam core having extremely low density of 40 kg x m(-3) and 48 kg x m(-3) were used for manufacturing the sandwich panels. Eight different configurations were constructed by hand lay-up followed by vacuum bagging. According to ASTM C393/C393M standard, the sandwiches were subjected to three-point bending (TPB) tests. After performing the TPB tests, the composite sandwich specimens were examined under a stereomicro-scope to determine failure modes. The primary failure modes under quasi-static bending loading were found to be top face sheet failures due to fiber and matrix cracks and delamination, and core shear failures due to core crushing just below the top facing and core fractures. In addition, the consistency of the test results were verified and the effects of parameters were investigated by using statistical variance (ANOVA) and regression analysis. The study provides a valuable contribution to the literature regarding sandwich structures having extremely low-density foam core materials and may contribute to the material universe by introducing strong, stiff and lightweight sandwich composites. It provides a comprehensive comparison by considering the effect of different fiber types, fabric fiber orientations and core densities.