Bottom Panel Dilemna and Compromises

Context:

Bottom panel was intended to be structural, requiring high levels of manufacturing precision wrt cure temperatures, pressures as well as layer composition.
Bottom panel, upon returning from lockdown 1, had a layer of cured epoxy adhesive film on it (shown above).
Cured epoxy does not bond well with new uncured epoxy

Phase 1: assessing if the current layup was “good enough”

During the initial cure (containing 4 layers of carbon fiber, 1 layer of adhesive film and nomex core), vacuum was not fully achieved. This leads to poor layer compaction as well as poor carbon fiber cure quality (see carbon fiber basics pages for more info). Upon inspection, it was determined that there were not enough physical defects to justify redoing the entire panel. However, there were enough to call into question the panel’s actual mechanical properties vs the stated/assumed properties used in the simulations. Thus, it was decided that the bottom panel needed to move forward as a non-structural panel. This meant there were changes to the chassis that needed to be made, in order to ensure that it could handle the loads.

Phase 2: making the most of what we have

The bottom panel needs to be adhered to the chassis. This posed a challenge because, as mentioned above, cured epoxy is hard to work with.

After trials, research and consultations with Prof. Montesano, it was decided that we would opt for the mechanical bonding option. This meant utilizing surface imperfections to bond as opposed to chemical bonding (epoxy).

Phase 3: planning and execution

This is primarily outlined in the “demolding and reinforcements” page in the same folder as this page.