Monday, March 13, 2017

Front battery boxes in the build process finally

I got some feedback on the previous blog.  It was decided that the stresses in the weld would be marginal.  We also did a few more assembly studies and could not decide if the boxes would be able to slide in to the vehicle.  THEREFORE, a slight adjustment and a few more runs on the analysis has yielded:

The changes include taller tubes, 1"->1.5" on the horizontal sections.  The 45° center section, this reduced the stress on the lower side of the section from when it was 90° degrees, and further allowed the battery box more room to slide into the rear section.  The front I-Beam connection also changed from welding to the center webbing to sitting on the beam, this significantly changed the area of loading for the better and will further aid the insertion of the DMOC into the bay under the hood.

All around a marginally more difficult design to cut and weld, but the safety factor went up to 2.7 at yield and 3.7 to ultimate on a 3-2-1 loading.  I don't see us applying a million pothole cycles while turning at speed and applying full brakes.   Then again, we use Windsor road almost every day...
Thank to Don and Brad for their stress analysis discussions leading to this solution.
FYI, the analysis was done by; taking the PTC ProE solid model, importing it into (, using the split surface tool in OnShape such that uniform loads could be applied to the z-bars, importing the OnShape model into (, using Simscale to mesh, load, apply boundary conditions, and post process the FEA.

Material has been ordered!!!!  We might actually get something done over Spring Break!

 The boxes each hold 11 modules for 22 in the front.  We have reconfigured the Leaf cell connections in the retainer, next step, figure out the order to put the pins back in the connector for the BMS:

We have two identical pieces like the one above.  The missing connections in the corners are where we will attach between the packs.

1 comment:

  1. Glad you got this part figured out, looks like it should be a solid plan to move ahead with.