Photoelastic characterisation of interfacial stress distribution of a single short-fibre model composite under tensile loading

摘要

The shear stresses at the interface between a polyester fibre and an epoxy matrix in a short single-fibreudmodel composite specimen were measured using photoelasticity. A dark-field circular polariscope wasudemployed to monitor the stress field in the matrix during tensile loading. With this method, the stressudlevel of a Nth isochromatic fringe in the matrix intersecting the fibre can be obtained. The modeludcomposite specimen was loaded in uniaxial tension and the isochromatic patters along the fibre-matrixudinterface were recorded for several increments of load. In the experiment, it was observed that theudnumber of fringes increased with the applied load, which indicated an increase in the stress transferudfrom the matrix to the fibre. Debonded zones were also identified where the shear stresses were at audminimum. The shear stress vs distance along the fibre plot showed that monitoring isochromatic fringeudpatterns can accurately measure the stress transfer and stress distribution at the interface in theudthermoplastic-thermosetting system presented in this work.