Papers by Keyword: Honeycomb Sandwich Composite

Abstract: The experimental investigation on the compressive properties of honeycomb sandwich composite panels was carried out in this paper. The local compressive specimens and global compressive specimens were manufactured for compressive experiment. The test fixture has been designed and manufactured to examine the compressive behavior of honeycomb sandwich panel. The results indicate that there is no buckling occurred in local compressive specimen skin during the whole compressive experiment. The average failure load of local compressive specimens is 106884 N. The local buckling increases with the loading until the global compressive specimens are unstable. The fracture positions locate along the horizontal line at the middle height of global compressive specimen, which is different from local compressive specimens. The average buckling load and failure load of global compressive specimen are 31850 N and 82282 N respectively.

Abstract: This paper investigates nonlinear responses of honeycomb sandwich composite under externally applied loads theoretically and experimentally. In the experimental work, honeycomb sandwich composites made of an aluminum honeycomb core and glass fiber reinforced polymer (FRP) laminate surfaces were loaded under in-plane tension and out-of plane bending up to failure. Stress-strain curves or load deflection plot together with elastic moduli and ultimate strengths were obtained. An energy approach was used to establish a nonlinear constitutive relationship for the honeycomb sandwich composites. Making use of the superimposition ability of the strain energies of all of the walls of the RVE, a nonlinear constitutive relationship for the honeycomb core was obtained. The thus obtained relationship was incorporated with a laminate theory and the bridging model to analyze nonlinear responses of the honeycomb core and FRP surface sandwich composites up to failure. The composite failure was detected micromechanically, i.e., based on the failure status of its constituent aluminum core, reinforcing fiber, polymer matrix, and adhesion layer. Stiffness discount was applied respectively to the failed composing element. The predicted nonlinear stress-strain curves under tension and load-deflection relationship under three-point bending were compared with the experimental measurements. Favorable correlations have been obtained.

Abstract: Theoretical formulas for effective elastic modulus and Poisson's ratio of honeycomb core materials were proposed considering the bending, axial and shear deformations of cell walls. Theoretical results obtained by the formulas showed orthotropic elasticity and large Poisson’s ratio, which were comparable to results by finite element analysis(FEA). Tensile test of honeycomb sandwich composite(HSC) plates was performed for analysis of their deformation behaviors and interlaminar stresses. Equivalent plate model using the theoretical results of honeycomb core layer show that interlaminar shear stress occurring due to large difference of Poisson’s ratio between skin and honeycomb core layers led to the delamination in HSC plate under tensile loading. Load-displacement behavior of HSC specimen simulated by equivalent plate model coincided fairly with that of detailed FEA model similar to experimental results.

Abstract: The strength characteristics as well as local deformation behaviors of honeycomb sandwich composite (HSC) structures under three-point bending loads were investigated in consideration of various failure modes such as skin layer yielding, interface-delamination as well as shear deformation and local buckling in the core layer. Various types of aluminum honeycomb core and skin layer were used for this study. Their finite-element simulation was performed to analyze stresses and deformation behaviors of honeycomb sandwich plates. The results were very comparable to the experimental ones. Consequently, thicker skin layer, smaller cell size of honeycomb core and less delamiantion had dominant effects on the improvement in strength and deformation behaviors of honeycomb sandwich plates.