Experimental modeling of nonlinear photothermal effects in composite materials

摘要

An experimental model system was developed in order to investigate the nonlinear effects that originate from vibrating boundaries in photothermal techniques. It followed a primary investigation that demonstrated the effect of thermoelastic bending particularly studied in fiber reinforced composite laminates. The model consisted of such a laminate with a hole and a metallic piston piece that was made to fit exactly inside the hole. The piston position, and consequently the width of the air gap between laminate and piston, was periodically varied while collecting a IR radiometric photothermal signal. The nonlinear effect caused by the varying boundary condition experiment resulted in the generation of mixing frequency components in the photothermal signal.