Characterization of balsa sandwich structures with fiber reinforced epoxy face sheets
Rico Blei, Rafal Stanik, Maik Gude, Andrzej Czulak
Quarterly No. 3, 2017 pages 126-130
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abstract The aim of this study was to examine the effect of different material combinations and process parameters on the material characteristics of sandwich structures. Therefore, the material properties of sandwich structures made from woven fabrics (glass/ flax fibers) and powder epoxy resin as well as balsa cores were investigated. These material combinations are highly interesting for customized lightweight constructions as they bear the potential to construct three-dimensional free shape structures. The structural set-up observed during this study consists of balsa wood which is covered with two outer layers of fiber reinforced epoxy resin. In order to compare the effects of these outer layers on the material behavior, specimens with woven fabrics made out of glass and flax fibers were manufactured. During a hot pressing process, the fiber bed was infiltrated with powder epoxy resin while being pressed to the balsa core. To determine the material characteristics of the manufactured composite, mechanical tests such as 4-point-bending (DIN 51227) and peel tests (DIN EN 1464) were executed. Further investigations consisted of microscopic analyses to ensure quality control of the specimens. Additionally, the degree of wood penetration was examined during this screening process. It was revealed that the specimens with glass face sheets yielded a higher flexural strength (average: 19.54 MPa) and modulus (1815.12 MPa) than the flax specimens (strength: 16.14 MPa; modulus: 1353.83 MPa). Furthermore, the average peel resistance of the glass specimens (1.54 N/mm) was slightly higher than the average value of the flax fabric specimens (1.38 N/mm). Concerning the infiltration behavior, greater penetration of the balsa core was noted when using glass face sheets. Keywords: glass epoxy composite, flax epoxy composite, woven fabrics, powder processing, balsa sandwich structure, material characterization