Experimental studies on the punch shear characterization of glass/epoxy/CNTs laminate nanocomposites

The effects of specimen diameter to punch diameter (span ratio) and loading velocity are experimentally studied on quasi‐static punch shear (QS‐PS) properties of laminate nanocomposites. Nanocomposites specimen in this work is composed of 12 layers of plain weave glass fibers with areal density of 200 g/m² which are made by hand lay‐up method under pressure. Resin is composed of a two‐component epoxy; diglycidyl ether of bisphenol A (Epon 828) as the base and modified cycloaliphatic amine (Epikure F‐205) as the curing agent. Multi‐walled carbon nanotubes (MWCNTs) modified by hydroxide (COOH) are used with 0%, 0.1%, 0.5%, and 1% ratio in weight with respect to the matrix. Also, two span ratios (5 and 10) and two loading velocities (5 mm/min and 500 mm/min) are utilized. Test results show that with a half span ratio in neat samples, the total penetration energy is approximately constant but the contact force increases about 20%, displacement at peak load decreases about 57%, and target plate deformation is reduced until full penetration. With increase of loading velocity from 5 to 500 mm/min, total absorbed energy of neat samples is increased about 47%. The results show that carbon nanotubes reduce the strength of the composites in which their failure mechanism is shear type. POLYM. COMPOS., 39:E2096–E2105, 2018. © 2017 Society of Plastics Engineers