Three-point bending properties of carbon fiber/honeycomb sandwich panels with short-fiber tissue and carbon-fiber belt interfacial toughening at different loading rate

The bending performances at different loading rate are studied for carbon fiber/honeycomb sandwich panels toughened by short aramid fiber tissues and carbon fiber belts. The carbon fiber belts are stitched cross the pores of honeycomb core for interfacial improvements. Three-point bending tests at different loading rates are carried out to investigate the effect of short aramid fiber tissue and carbon fiber belt on mechanical properties of carbon fiber/honeycomb sandwich specimens. Experimental results firstly indicate that the short-aramid-fiber interfacial toughening and carbon fiber belts toughening could both enhance the energy absorption and peak load of sandwich specimens at loading rates ranging from 2 mm/min to 500 mm/min. The failure modes and microstructures of toughened specimens are observed to analyse and explain the underlying mechanism of enhancing effect. It is illustrated that crack isolation phenomenon is found to be the main mechanism for avoiding interfacial damage of the sandwich specimen.