Bow Optimization Choices
We were surprised by how flexible the first version of the bow was. It was designed with some flexibility in mind, but we felt that this version was able to deflect much too easily for us to be able to actually store energy in it. In light of this, we have opted to make multiple design changes in order to optimize further prints. Specifically, the center of the bow had visible stress concentrations when the bow was flexed which contributed to less than desirable performance. In addition, we noted that too low of an overall height was chosen for the drawstring attachment points which caused the drawstring to drag across the main body. In order to mitigate this, the center of the bow will be doubled in the middle (0.5″ thickness) and then taper down to 0.25″ thickness on the sides. This should serve to increase the overall inertia of the bow and lead to a higher energy dissipation upon firing. Lastly, the drawstring attachment points will be elevated by 0.25″ in order to eliminate dragging across the body. We felt comfortable with our print orientation as it did a great job of loading the fibers axially and therefore distributed the forces well.
We have sent our updated Solidworks files to the TA and are waiting on version 2 of our bow. Upon receiving version 2, we will conduct more thorough testing and take pictures for this blog post.