Accession Number : ADP006006

Title :   The Static Strength of Bolted Joints in Fibre Reinforced Plastics,

Corporate Author : IMPERIAL COLL OF SCIENCE AND TECHNOLOGY LONDON (UNITED KINGDOM) DEPT OF AERON AUTICS

Personal Author(s) : Matthews, F. L.

Report Date : MAR 1988

Pagination or Media Count : 9

Abstract : Joints in glass fibre/epoxy (GFRP) and 'Kevlar' fibre/epoxy (KFRP) laminates show similar characteristics to those in carbon fibre/epoxy (CFRP) but with differences brought about by the low elastic modulus of glass of fibres, and the low compressive strength of 'Kevlar' fibres. The current paper presents data for GFRP laminates manufactured manufactured from layers of unidirectional fibre prepreg, and for KFRP laminates manufactured from layers of balanced, bi-directional, woven fabric prepreg. Comparative data for CFRPeek is also given. As far as GFRP is concerned, tests on single-hole joints show that the effects of width, end distance, hole size, bolt clamping pressure and stacking sequence are similar to those in CFRP. In general, strength levels for GFRP are about 20% below tose for CFRP. The best lay-up is judged to be 0/ + or - 45, with 60% of the plies at + or - . A stronger inter-delaminate rather than showing in-plane shear or tensile cracking. Due to the nature of the prepreg the range of possible lay-ups for KFRP is restricted; only 0/90, + or - are tested. Bearing strengths are generally in the range 500-600 MN/m2, i.e. 25-30% below GFRP. Overall behaviour is found to be similar to other FRP although the ultimate failure mode is almost invariably tensile. There is evidence that the inherent compressive characteristics of 'Kevlar' fibre contribute to the low bearing strength. Surprisingly, although ver large hole distortions are seen at failure there is very little evidence of resin cracking. (SDW)

Descriptors :   *BOLTED JOINTS, *FIBER REINFORCEMENT, *REINFORCED PLASTICS, *STRENGTH(MECHANICS), BEARING STRENGTH, BOLTS, CARBON FIBERS, CLAMPS, COMPRESSIVE PROPERTIES, CRACKS, FABRICS, FAILURE, FIBERS, GLASS FIBERS, HOLES(OPENINGS), LAMINATES, LAYERS, LOW STRENGTH, MODULUS OF ELASTICITY, PAPER, POLYMERS, PRESSURE, RANGE(DISTANCE), SEQUENCES, SIZES(DIMENSIONS), STACKING, STATICS, TENSILE PROPERTIES, UNIDIRECTIONAL, WEAVING.

Subject Categories : Laminates and Composite Materials
      Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE