Composite Materials Testing
This page details some testing of some simple composite laminates I have constructed. Epoxy resin has been used as the matrix, carbon tissue, kevlar cloth and glass tissue have been used as reinforcements, and balsa as a core material. The tests were performed in order to (a) gauge the strength of the balsa-epoxy-carbon/kevlar laminated fins that I have been making, and (b) to determine tensile strength of epoxy-woven cloth composites that might be used to construct motor casings (hopefully coming soon!). Also, unreinforced balsa and plywood has been tested for comparison purposes.
The epoxy resin system used was from West System. The 105 resin was used in conjunction with the 206 (slow) hardener. Both resin and hardener were dispensed from pumps to ensure that the proportion of resin to hardener was accurate. Fiber reinforcements tested were carbon fiber tissue (0.5oz/yd2, 17g/m2, from Shadow Composites), woven kevlar cloth (7oz/yd2, 235g/m2, from Shadow Composites), and glass fiber tissue (weight unknown, source unknown). A core of 3/32" (2.4mm) balsa wood was used. The plywood samples tested were 6mm birch plywood.
Samples were constructed by cutting 1cm x 5cm pieces of the reinforcement material and balsa core, and a piece of reinforcement was wetted out with epoxy and placed either side of the core material. The laminate was then compressed between two sheets of polythene (black bin bag) with weight applied for 24 hours at room temperature. The polythene sheets were easily removed, and the excess resin squeezed out of the laminate was removed using a file.
Masses were measured on a laboratory balance to two decimal places. Dimensions of each sample were measured using a micrometer. Tensile strength tests were performed by Dr. Owen J. Guy in the Materials Engineering Department at the University of Wales Swansea.
| Sample type | Sample # | Mass / g | Thickness / mm | Cross-sectional area / m2 | Breaking force / N | Tensile strength / N m-2 |
|---|---|---|---|---|---|---|
| Plywood | 1.1 | 2.33 | 6.1 | 6.4 x 10-5 | 2295 | 35.9 x 106 |
| 1.2 | 2.42 | |||||
| 1.3 | 2.50 | |||||
| Balsa | 2.1 | 0.16 | 2.1 | 2.1 x 10-5 | 250 | 11.9 x 106 |
| 2.2 | 0.18 | 2.1 | 2.1 x 10-5 | 250 | 11.9 x 106 | |
| 2.3 | 0.16 | 2.1 | 2.1 x 10-5 | 147 | 7.0 x 106 | |
| Balsa-Glass tissue | 3.1 | 0.74 | 2.9 | 3.0 x 10-5 | 620 | 20.7 x 106 |
| 3.2 | 0.76 | 3.0 | 3.1 x 10-5 | 608 | 19.6 x 106 | |
| 3.3 | 0.74 | 2.9 | 2.9 x 10-5 | |||
| Balsa-Carbon tissue | 4.1 | 0.56 | 2.7 | 2.7 x 10-5 | 917 | 34.0 x 106 |
| 4.2 | 0.59 | 2.6 | 2.6 x 10-5 | 812 | 31.2 x 106 | |
| 4.3 | 0.62 | |||||
| Balsa-Woven Kevlar | 5.1 | 0.82 | 3.0 | 3.2 x 10-5 | 2075 | 64.8 x 106 |
| 5.2 | 0.89 | 3.2 | 3.6 x 10-5 | 1763 | 49.0 x 106 | |
| 5.3 | 0.80 |
Coming soon! Or you can draw your own.