The influence of impactor energy and geometry on degree of damage of glass fiber reinforced polymer subjected to low-velocity impact
Konrad Dadej, Patryk Jakubczak, Jarosław Bieniaś, Barbara Surowska
Quarterly No. 3, 2015 pages 163-167
DOI:
keywords: fibre-reinforced polymer composite, low-velocity impact, delamination, impactor geometry, failure
abstract The presented research was devoted to determining the influence of impactor geometry on the degree and character of failure of a glass fibre reinforced epoxy matrix subjected to low-velocity impact. Furthermore, the relevance of impact energy and lay-up configuration of each composite plate were analysed. The subject of the tests were autoclave manufactured 8-ply glass/epoxy prepregs of the following lay-up [0/90]2s, [±45]2s and [0/±45/90]s. The laminates were subjected to low-velocity impact tests according to norm ASTM D7136 with the application of hemispherical impactors: 12.7 mm (0.5"), 25.4 mm (1") and 38.1 mm (1.5"), for three impact energies 5, 10 and 15 J. The conducted tests indicate the correlation between the diameter of the indenter and the load applied, on the degree and character of damage of the glass/epoxy composites, i.e. the higher the load, the greater the laminate failure, regardless of the lay-up configuration. Similarly, the degree of failure is greater when the diameter of the hemispherical impactor is smaller. The dominating types of failure are delaminations at the interface between the composite layers, and matrix cracks. This might occur as a result of considerable shear stresses at the laminate interface and delamination observed after impact with a smaller-diameter impactor. This is best observed in the case of a quasi-isotropic lay-up configuration, where the superposition of the delamination surface area was the highest. The use of a hemispherical impactor of the largest diameter causes bending stresses in the lower layers of the composite, and the presence of characteristic cracks in the matrix and/or at the fibre/matrix interface.