First Layup

Nicholas A -

Hello everyone!

This week, I made the composite panel for the control group that I will cut and test next week. The hand layup process is fairly simple. First, I do my best to cut 12 inch by 12 inch squares from the roll of fiberglass. This can be difficult because the weave can stretch and bend on the table, so when I cut it, I don’t get perfect squares. I cut out 8 layers to make sure the panel will be thick enough to test. Then, the epoxy is mixed with hardener in a cup. I stipple the epoxy mixture onto each layer of fabric to saturate it with epoxy. Once a layer is saturated, I add the next one until I have all the layers. The epoxy cures in about 24 hours, so I can leave it when I’m done. 

The composites I am making are fiber-matrix composites, meaning they have a weave of fibers surrounded by a filler material. In this case, I am using fiberglass with an epoxy matrix. Composite laminates (laminate being the entire assembly) have a certain number of layers, each called a ply or lamina, each aligned in a specific direction. I am making an 8-layer composite, meaning I have 8 sheets of fiberglass that I stack onto each other. All of my layers are aligned in the 0 direction, meaning they all face the same way with respect to a predetermined direction. However, layers could be made in 30, 45, or 90 degree angles as well. Having layers oriented in different directions changes the overall characteristics of the laminate. 

I’ve attached a picture of the final laminate curing on the table. Next week, I’ll add grips to the laminate, cut it, and perform the tests.

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    dishita_k
    Nice work on the composite panel! It sounds like making sure the fiberglass squares were even squares was a bit of a challenge. I'm curious to learn more about how the different layer orientations (0, 30, 45, 90 degrees) affect the characteristics of the laminate. Could you please explain that a bit?
    March 4, 2024 at 4:41 pm - Reply
    nicholas_a
    Hi Dishita, making even squares out of the fiberglass is a bit difficult, but I think I've found a good technique. Having different layer orientations affects how the laminate responds to stresses. For this project, I am assuming a single layer is orthotropic, meaning it has different elastic properties in the x, y, and z directions. If we orient this layer at 30 degrees, for example, since it has different properties in each direction, it won't necessarily strain in the same direction as the force. This is caused by the fibers carrying the load in a certain way. You can imagine the entire laminate as more or less a sum of how each individual layer responds to force. We can use this to optimize the laminate to be able to handle forces in the way we want.
    March 6, 2024 at 11:01 am - Reply
    Ms. Bennett
    Hi Nick, this looks like really interesting hands-on aspect of your project. Did you do this work in a lab? Or was it on your own?
    March 7, 2024 at 9:38 am - Reply
    nicholas_a
    Hi Ms. Bennet, this work is done at the machine shop of AXFAB at ERAU.
    March 12, 2024 at 11:58 am - Reply

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