Tj. Matthams et Tw. Clyne, Mechanical properties of long-fibre thermoplastic composites with laser drilled microperforations 2. Effect of prior plastic strain, COMP SCI T, 59(8), 1999, pp. 1181-1187
An examination is presented of how the mechanical properties of a PPS-based
carbon-fibre composite, in which an array of fine holes had been generated
by laser drilling, are affected by the prior imposition of large plastic s
trains. This was done in order to explore how a typical high temperature fo
rming operation would be likely to change the microstructure of such microp
erforated material and hence to affect its mechanical properties. Tensile s
trains of up to 200% were imposed in a drawing operation, with imposed tran
sverse constraint sufficient to ensure that the fibres remained within the
plane of the specimen. After drawing, specimens were tested to failure in t
ension at room temperature. It has been found that the strength and stiffne
ss of the material remains relatively dose to the corresponding values prio
r to deformation for strains of up to about 50%. Above this level, both str
ength and stiffnesses were observed to decrease fairly rapidly. These resul
ts have been explained in terms of the microstructural changes which accomp
any the drawing process. (C) British Crown Copyright 1999, DERA. Published
by Elsevier Science Ltd with permission.