EC! Laminate Sample #4:
- Reinforcement: 200g RC200 woven, 300g HEC300 unidirectional
- Resin: Gurit SE84LV
- Core: none
See below for laminate fiber volume fraction calculation based on 3000g / square meter of fiber and the as-weighed panel.
- Fiber Weight Fraction: 0.67
- Fiber Volume Fraction: 0.55
Total weight: 14.75 oz (418g) per square foot. Approx 4.4kg per square meter. Thickness 2.94mm.
Note: The video title has the wrong weights because “4” and a “3” are close together on the keyboard – and I’m not much of a proof-reader. Sorry!
Video:
Details:
Symmetrical laminates are mirrored about their mid-plane or “neutral axis”. Here the plies are mirrors of each other across this middle ply of 200g woven. This limits the possibility of warping. Quasi-Isotropic (QI) laminates have approximately the same quantity of fiber running in each direction, so here there are 600g or uni at 0,90,+45,-45 degrees. Balanced laminates have equal numbers of opposing laminates – if there are two plies at +45, there will also be 2 at -45. Thicker laminates or lighter material make symmetry, balance and QI orientation easier because the “steps” are less distinct. Here the 200g surface layers are there to make cutting easier and to toughen the surface. The middle one is there to bring the total thickness to 3mm. Ideally it would be alternating unidirectional plies all the way through.
Note: this graphic is wrong in that the word “balanced” should be “symmetrical” – I messed this up.
Fiber Volume Fraction Calculation:
Things to Improve:
The only real issue here was the excess bleed of resin. Even so, 32% resin is probably not mechanically inferior to 37% resin – but its getting close! The easiest solution would be to ramp the temperature faster, causing the resin to start to gel sooner and not have as much opportunity to bleed off. Using a smaller or reduced-area perforated release film would help too. Pre-preg peel ply would help as well – but I don’t have any of that.