Papers by Keyword: Interlaminar Properties

Abstract: The present research work describes the fabrication and interlaminar properties testing of carbon fiber aluminum metal laminates (CARALL). CARALL was fabricated through hand layup process followed by compression molding technique and interlaminar properties were assessed through double cantilever beam (DCB) test short beam and flexural test. Different treatments were performed on the surface of aluminum alloy and parameters were optimized to ensure good adhesion between metal sheet and carbon composite layer. Pull-off adhesion test was performed to gauge the adhesion strength of epoxy resin on aluminum alloy sheet. Effect of Multi-wall carbon nanotubes (MWCNTs) was also investigated on the interlaminar properties of CARALL. Treated surface of aluminum alloy sheet was examined under Optical and Field Emission Scanning Electron Microscopy (FE-SEM). Porous surface was evident on aluminum sample due to surface treatment which contributes towards better adhesion between epoxy resin and metal surface through mechanical interlocking and diffusion mechanism. FE-SEM and stereo microscopy was also performed on fractured DCB samples and underlying fracture mechanism was discussed. Test results demonstrated that addition of MWCNTs deteriorated the interlaminar properties of CARALL by weakening the interface between treated aluminum surface and carbon composite.

Abstract: Based on the “ex-situ” toughening concept, thermoplastic nylon (PA) nonwoven fabric with high porosity was chosen as the toughening layer, and the interlaminar toughened composites were fabricated via RTM process. Compression strength after impact (CAI) properties were investigated as well as the toughening mechanism. The results indicated that there is no bicontinuous phase structures formed by reaction-induced phase decomposition and inversion. The PA nonwoven fabrics still kept the original structure in composites interlaminar, and formed a macroscopical bicontinuous structure with the matrix resin, which also showed remarkable toughening effect. The CAI value increased from 212MPa to 281MPa.

Abstract: The influences of low temperature on the interlaminar properties for PBO fiber/epoxy composites have been studied at liquid nitrogen temperature (77 K) in terms of three point bending test. Results showed that the interlaminar shear strength at 77 K were significantly higher than those at room temperature (RT). For the analysis of the test results, the tensile behaviors of epoxy resin at both room temperature and liquid nitrogen temperature were investigated. The interface between fiber and matrix was observed using SEM images.

Abstract: Failure by delamination of composite laminates due to low velocity impact damages is critical because of the subsurface nature of delamination. Traditional methods such as stitching and Zpinning, while improving interlaminar properties in woven composites, lead to a reduction of the inplane properties. To alleviate these problems, use of Tetra Ethyl Orthosilicate (TEOS) nano fibers manufactured using electrospinning technique in fiber Glass-Epon composite laminates is investigated for their potential to improve the interlaminar properties. Electrospun coated fiber glass woven mats are impregnated with epoxy resin using Heated-Vaccum Assisted Resin Transfer Moulding (H-VARTM) process. The interlaminar properties of the nano engineered hybrid composites obtained using ASTM Double Cantilever Beam (DCB) tests and short beam shear tests are compared with those without the presence of electrospun fiber layers, to study their influence. The short beam shear tests revealed a 20% improvement due to presence of TEOS interlaminar electrospun nanofibers. It is also noteworthy that fibers cured at different temperature levels had variation in performance as observed in MSBS test results.