Application of bridging-law concepts to short-fibre composites - Part 2. Notch sensitivity

This is the second paper in a series of four where notch sensitivities, fra cture energies and bridging laws are studied in short-fibre polymer composi tes. Estimates based on an order-of-magnitude criterion indicate that previ ous notch sensitivity studies on short-fibre composites are limited to smal l notch sizes in the ductile region. For this reason, centre-hole notch sen sitivity is studied experimentally as a function of relatively large notch diameters in the range 15-60 mm. The materials have different matrices, gla ss-fibre content and fibre lengths. The onset of notch sensitivity is obser ved for all materials (glass-mat thermoplastics, sheet-moulding compounds a nd chopped-strand-mat laminates), although large notch sizes are required. The reasons for this are discussed as well as the influence of different ma terial parameters. On the basis of the material bridging law and laminate Y oung's modulus, it was possible to rank different short-fibre composites wi th respect to notch sensitivity. (C) 2000 Elsevier Science Ltd. All rights reserved.