An Experimental and Numerical Study of Low Velocity Impact of Unsaturated Polyester/Glass Fibre Composite

In this paper validation of experimental and numerical results of low-velocity impact tests of unsaturated polyester/glass fibre composite laminate has been carried out. Impact response of composite laminates was experimentally studied with drop-tower Instron 9250HV determining impact force, energy absorption and deflection. In addition, quasi-static testing equipment Zwick Z100 has been used to determine material mechanical properties to ensure good input data for numerical predictions. Numerical model has been created with the finite element commercial code ANSYS/LS-DYNA to simulate impact response of composite laminate. Also non-destructive ultrasonic B- and C- scan imagining with USPC&nbsp;3010 system has been used to identify the deformation regions in the specimens and compare to simulation results. During the impact test all samples were perforated, showing brittle response followed by matrix cracking and delamination. Overall good agreement between experimental and simulation results was achieved, comparing impact characterizing parameters as load, energy and deflection. Discrepancy has been observed between ultrasonic scanning and simulation code ANSYS/LS-DYNA results of rupture and delamination. Simulation shows less uniform and larger deformation than it was experimentally observed.http://dx.doi.org/10.5755/j01.ms.17.4.773</p

Polyisoprene/Nanostructured Carbon Composites for Applications in Temperature Sensors

The studies of electrical properties of thepolyisoprene (PI) matrix/high structure carbon black (HSCB)composites (PCBC) with various concentrations (8, 9, 10 and 11mass parts) of filler have been carried out in the temperatureinterval of 90K–330K. In this paper we focus on the investigationof direct current (DC) conductivity in a low-temperature regionwith negative temperature coefficient of resistivity (NTCR). Ithas been proven that variable range hopping (VRH) conductionis dominated by hopping of carriers among localized states in alow-temperature range. At higher temperatures the nearestneighbour hopping (NNH) conductivity or constant rangehopping charge transport takes place. The reversibility as well assmall hysteresis of resistance change versus temperatureindicates prospective temperature sensor application for PCB