| Name: | Description: | Size: | Format: | |
|---|---|---|---|---|
| 551.34 KB | Adobe PDF |
Advisor(s)
Abstract(s)
The specific characteristics of composite materials, like carbon fibre reinforced plastics, have been
leading to their rising importance and widespread use. As these parts are normally produced in a nearnet
shape, secondary operations, like drilling, are necessary prior to their assembly in complex
structures. It is still difficult to define a machining process that enables free damage holes, due to the
peculiar laminar nature of these materials. So, the definition of a drilling process that minimizes
delamination and increases reliability in produced parts combined with satisfactory cost and
productivity is still of major importance in the composites manufacturing industry.
In this paper two sets of unidirectional coupons from plates with carbon fibre as reinforcement and
epoxy resin as matrix, are drilled using five different drilling tool strategies and two feed rates for
uneven damage extension. One of the strategies is the use of a pre-drilling option. Then the
delamination is assessed using enhanced radiography and, finally, two diverse mechanical tests are
performed on the resulting coupons: three point bending and pin bearing.
The results allowed establishing and modelling, with the help of statistical tools, the relations
between the damaged area caused by drilling and the material’s mechanical resistance. The bending
resistance does not vary greatly with the damage area. On the other hand, the bearing resistance
decreases with the increase of the damaged area.
Description
Keywords
Composite materials Drilling damage Damage quantification Mechanical testing