In this study, the dynamic response and energy absorption characteristics of different combinations of fiber-reinforced pultruded hybrid composites made of unidirectional glass and graphite fiber/epoxy have been investigated. High strain-rate compression experiments were conducted on cylindrical specimens at an average strain rate of 700/s using a modified Split Hopkinson Pressure Bar (SHPB). Failure was monitored with a high-speed video camera, and effects of hybridization on the dynamic behavior of pultruded composites were evaluated. It was found that for a given fiber volume fraction, placing glass fibers in the inner core results in a higher ultimate compressive strength, specific energy absorption, and in general a better dynamic performance with lower density.

The excited state properties of dyes become important under intense illumination of a short laser pulse. The pulse induces a significant population in an excited state which will have different absorptive properties, this causes a change in absorption of the incident pulse within its duration. An increase in absorption arises from molecules in an excited state having an absorption greater than the corresponding ground state.The z-scan technique has been used to measure the induced absorption of a carbocyanine dye 1,1′,3,3,3′,3′- Hexamethylindtricarbocyanine Iodide (HITCI) for laser pulses of different wavelengths. An optical parametric oscillator pumped by the third harmonic of a Q-switched Nd:YAG laser was used. Z-scans were taken at a number of different wavelengths between 460 and 630 nm. Data is presented which shows the spectral region where induced absorption occurs. An eight level rate equation model is used to predict the non-linear behaviour and to fit to the experimental data, good correlation is found between the model and data.