Adhesive Strength

The battery modules must be secured to the catamaran in such a way so that in rollover, the modules do not come loose from the catamaran. As the car rolls over, the adhesive is loaded more similar to peel loading (where all of the force is concentrated on the leading edge) than to shear or normal loading as it would be in normal operation. Peel strength is generally used on materials that are flexible, so for our case, I am wondering if the loading will be more similar to an unequally distributed loading, or just a load with normal and shear components, as the steel of the clickbond bases is likely stronger than the adhesive (or at least on the same order of magnitude).

To note, all of these calculations assume that the carbon fiber layers DO NOT delaminate.

So, we must do some calculations to figure out if the adhesive will be adequate. The following links/images help to explain some of the testing methods and calculations.

https://www.andilog.com/define-peel-strength.html
https://www.admet.com/testing-applications/testing-standards/astm-d3330-tape-adhesion-strength-testing/

https://www.youtube.com/watch?v=I1SWCqNnE7c

The peel strength is defined as the average load during the test, divided by the width of the leading edge of the sample.

Clickbond Loading

Details:
Width of front edge → assume width of the trimmed baseplate = 19.1mm
Battery Module Mass = 50 cells * 50g + 200g = 2.7kg → 3kg (approx.)
5G rollover applied force = 3kg * 9.81 = 30N (approx.)

Peel Loading = Rollover Force / Width of Front Edge
= 30N / 19.1mm = 1.57N/mm = 1.57kN/m

For CB359 adhesive, the max is 10.5kN/m, so we have a large margin of safety, which I am comfortable with, given the fudging and guessing of some of the numbers.

For completeness, let’s also check shear (though I’m positive it won’t fail in this manner).

Shear Loading = Force / area = 30N / (pi * (31.8/2)²) = 0.04MPa
Max Load = 31.0MPa (according to datasheet for CB539)
Factor of Safety = 31.0 / 0.04 = 775.

This is a comically large factor of safety, but proves that the adhesive we would like to use is more than adequate - but the peel will definitely fail first (or the catamaran)

Clickbond Datasheet, adhesive values given on Pg 51: https://www.clickbond.com/Uploads/SupportPDF/636360848351405271.pdf