Six image phase stepped photoelasticity for the quantification of the stress field around 25μm reinforcing fibres

Abstract

a b s t r a c tA six image phase stepped photoelastic technique has been applied for the measurement of the interfacial shear stress distribution in the matrix resin along a reinforcing E-glass fibre of $25 lm in diameter at its end and at a fibre-break. Contour maps of the isochromatic fringe order and its corresponding isoclinic angle, which are related to the principal stress difference and direction relative to the fibre axis, could be obtained continuously using this photoelastic technique. Thus the actual interfacial shear stress along the fibre can be calculated. Furthermore in the presence of a fibre-break, interfacial debonding and matrix yielding during stress transfer was investigated. The micro-mechanics are shown to differ at a fibre-break compared to a fibre-end.

Visualization and Quantification of Stresses at the Ends of Short Fibers Embedded in Epoxy Resin

“…However, not only the properties of the constituents themselves, but also the properties of the interphase, which governs the transfer of forces between the relatively weak and compliant matrix and the reinforcing fibers [11] have an effect on the macroscopic properties of the composite. Several research groups have used the photoelastic effect [12,13] to visualize stress distributions at the interphase along the fiber as well as between adjacent fibers [14][15][16][17][18][19][20][21][22]. Photoelasticity allows quantification of shear stresses along the fiber interface as well as the distribution of principal stress differences.…”