2004 Volume 45 Issue 6 Pages 1839-1846
Titanium nickel fiber reinforced composites have great potential as intelligent materials. In this paper, titanium nickel fiber reinforced polycarbonate composites are developed with different prestrains of the embedded titanium nickel fiber. The effect of reducing the stress concentration, the enhancement of mechanical properties and the resistance to deformation of the titanium nickel fiber reinforced polycarbonate composites were investigated. The stress intensity factor, KI, was determined using photoelasticity and digital image processing to examine the crack closure effect in the titanium nickel fiber reinforced polycarbonate composites. The result shows that the crack closure effect is dramatically improved. The shape memory effect and the thermal expansion behavior of the matrix, caused by temperature increases, improve the resistance to fracture by decreasing the stress intensity factor, KI. The effect of crack closure is attributed to the compressive stress field in the matrix due to the shrinkage of the titanium nickel fibers above the austenitic finishing temperature (Af).