FAQ #295
How to fill out the SES EV Accumulator tab

Last Updated On 01/30/2020 06:33 PM by

sayovitz

Question
What is an accumulator side mount? Or a chassis side mount?
Answer
For accumulator mounting, the SES considers the accumulator modules as one solid block.
Most likely, your modules are basically rectangular.
Most likely, all the modules in the accumulator form a larger rectangle.
If it's not a rectangle, maybe it's an L-shape made of two rectangles.
Think in blocks.

Start by imagining your accumulator as a block with planar surfaces.
If it is a rectangle it has a front, a back, a top, a bottom, a left, and a right.
Most likely, you will have 10 mounts (Cells L22-23 -> Cell K25), and the five on the front match the five on the back, or the five on the right match the five on the left (U24, U25).

-- Accumulator mount sections --
These are broken into three subsections.

1. Where the fastener is in shear, at the centerpoint, what is the minimum distance to the block representation of the accumulator in the X, Y, and Z views?
"Outside" shows where the mount is sticking out. (In front of, to the left of, above, etc.)
Any "outside" measurements count towards AA65, "Total Surface Offset", which is the minimum lever distance from the fastener shear plane to the block representation of the accumulator.
Any "between" measurement is where the mount is between two planes.
Also in this section: Checks for fastener shear, fastener from the accumulator side, fastener tearout from the accumulator side.

2. If the mount is sticking out, it has to have sufficient bending strength.
The image in AY28 shows how to find the measurements for this section.
Sufficient bending strength is needed for:
the fastener trying to move around its axis, gusset thickness parallel to the shear plane
the fastener trying to move ALONG its axis, gusset thickness parallel to the axis

3. If the mount sticks out from the accumulator, the mount itself has to attach to the accumulator skin.
It may be bolted, bonded, or welded. (AA100)
Make a selection, and the appropriate cells will be activated.
If the mount material sticking out is continuous with the accumulator skin, select "Welded".

-- Chassis mount sections --
These are broken into four subsections.

4. Same ideas as Section 1, just on the chassis side instead of the accumulator side.
How far does the mount stick out from the chassis at the point where the fastener is in shear?
Note: Fastener shear should be identical to the accumulator section, since it's the same fastener/fasteners.

5. For a tube frame section, a bending check on the tubes themselves.
If the rest of your design is EQ, we will not reject for a low number here.
See FAQ 283: https://www.fsaeonline.com/cdsweb/rqa/ViewFAQ.aspx?faqnum=283
It is intended to make teams think about the underlying structure, and try to put your mounts in a smart, strong location.

6. Same ideas as Section 2, mount bending strength on the chassis side.

7 Same ideas as Section 3, mount attachment to chassis.
If the mount sticks out from the chassis, the mount itself has to attach to the chassis skin.
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