Some Aspects Concerning the Mechanical Characterization versus Manufacturing Technology of Sandwich Composite Materials

Abstract

The paper presents aspects observed during classic three-point test bending of various sandwich materials. These aspects outline the need to spare special attention to such test, in connection with the particular material and service life conditions it will endorse. Such special care is needed in conditions of scarcity of dedicated standards and some evasive formulations in the existing ones.

Study upon the Damage Tolerance of Thick Sandwich Materials

“…The sandwich materials studied in this research work will be used in the manufacturing of platforms of the tower supporting green energy power units and storage water tanks. The work continues previous studies [4,5,6] intended to offer arguments for the best choice of the material, in terms of nominal mechanical characteristics, reliability and low cost maintenance.…”

“…The sandwich materials having impregnated paper honeycomb core and GFRP skins prove to have high resistance. In order to increase the range of allowable deflections under bending loading in which they exhibit considerably higher strength than the counterparts with foam cores [4,5,6], the double core solution is a fully advisable one. The mid layer between the twin cores protects the bottom core from damages that might occur during low velocity impact events.…”

“…The thick sandwich materials studied in this work represent an extension of some of the previously evaluated sandwich materials. As the sandwiches with honeycomb core have proved to have the best specific strength [5], extension of this type of sandwiches was considered for heavy loaded materials embedded in the platforms, from single core to double core sandwiches. Specifically, the architecture of these materials was as follows: two 30 mm thick honeycomb cores with a mid-layer in-between, sandwiched between glass fiber reinforced polyester (GFRP) skins.…”

Links between Low Velocity Impact Results and the Residual Mechanical Performance of Sandwich Composite Materials

“…The materials used for the impact tests were sandwich materials having honeycomb or foam cores, and were described in the twin paper [3], where the bending behaviour was described. Only the 100 mm wide samples were impacted, in order to make possible the alignment with the small dimension imposed by the specific standard [4], which formalizes a rather common rule in dimensioning the samples used for such tests.…”

“…The next series of low velocity impact tests were made on samples having similar core materials, but thick skins [3]. The apparent damage produced on the impacted sides was always in the class of BVD and nothing was transmitted on the opposite side.…”