SYMPOSIA PAPER Published: 01 January 1986

Effect of Stress Biaxiality on the Transverse Tensile Strain-to-Failure of Composites


Thermoplastic matrices are now available with neat resin strain-to-failure values of up to 100%. These high strain-to-failure values could be expected to result in dramatically higher transverse strain-to-failure values in thermoplastic composites than epoxy composites. However, measurements of the transverse strain-to-failure of some thermoplastic composites have revealed only a modest increase in transverse strain capability. The objective of this work was to show that the matrix is biaxially stressed in a transverse tension test and that this significantly reduced strain-to-failure values.

To accomplish this objective, a specimen configuration was designed to introduce biaxial stresses into the neat resin. Data was generated on polyetheretherketone and polycarbonate, both ductile thermoplastics. Test results showed that biaxial stresses reduced the strain-to-failure of these materials by well over an order of magnitude. Thus, this work shows that, while a thermoplastic matrix's ductility may translate into composite toughness and delamination resistance, it does not necessarily translate into dramatically increased composite transverse strain-to-failure values.

Author Information

Nicholls, DJ
Captain, AFA/DFEM, U. S. Air Force Academy, Colorado Springs, CO
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Developed by Committee: D30
Pages: 109–114
DOI: 10.1520/STP35344S
ISBN-EB: 978-0-8031-4963-2
ISBN-13: 978-0-8031-0447-1