| dc.description.abstract | The accurate development of material allowables is a fundamental aspect of any
successful engineering design. Successful testing and development of material properties will
lead to accurate analysis of a structure, and predictable behavior of the end design. However, in
some cases (especially for laminated composite materials) the overall behavior of a structure
cannot be predicted by small scale testing. One of the leading causes of this is that edge effects
have a larger influence on small specimens, leading to under-prediction of overall material
behavior.
An experimental study was conducted to investigate the influence of machining induced
surface damage, and the viability of multiple techniques to mitigate that damage in order to
produce coupon specimen results that are more representative of the behavior of a bulk laminate.
Coupon extraction was conducted utilizing a rotary diamond saw. Two edge treatments were
tested (application of a commercially available cyano-acrolate adhesive, and a commercially
available epoxy resin). A pair of laminates was tested; each was designed to be susceptible to
delamination at a known position.
Tensile testing showed that application of a cyano-acrolate edge treatment improves the
performance of narrow 30 degree specimens by a margin of 11%. A statistically significant
difference was not observed in 45 degree laminates, epoxy coated specimens, or wide specimens.
There was a statistically significant performance difference between narrow and wide specimens,
including edge treated specimens. A 6% performance gap remained between narrow cyanoacrolate
coated specimens, when compared against wide specimens. This indicates that edge
stresses are only partially mitigated by the edge treatment applied to the coupon. | |
