A technique for the measurement of reinforcement fibre tensile strength atsub-millimetre gauge lengths

The strength of composite reinforcement fibres is normally measured on samp les of much greater length than the actual residual fibre lengths found in many composite materials. This is due to a number of limitations of the sta ndard techniques which are employed. We present a description of a techniqu e which enables values for the tensile strength of composite reinforcement fibres at short gauge lengths to be obtained. The technique is based on an adaptation of a micro-mechanical test apparatus for fibre pullout measureme nts. Data is presented which was obtained at gauge lengths of 180-380 mum o n E-glass and S-2 glass(R) fibres taken from different chopped reinforcemen t products. The technique can be used at gauge lengths as short as 20 mum. The data indicates that the values of average fibre strength in these produ cts are significantly below the pristine glass strength values. (C) 2000 El sevier Science Ltd. All rights reserved.