Wednesday, April 19, 2017

Friends of the project

I know it is not proper etiquette to go back and change pages in the blog at later dates, but the number of people stepping forward to help on the project is important to me.  I will only list a little about each person to recognize them for their support until they say they want more information about them or their business added.  Come back and visit this page to see who else is helping.

Top listing has no choice, THANK YOU to my lady for letting me play in not an inexpensive way on a project that had/has a lot of risk.  Oh, yeah, and to my boys for humoring me, but I know they want to drive it!

The final inspiration, he knew I was interested and provided a connection to tip the scale and get us going: Wolf

Project design overview soundboards :
Dad, despite this being a really dumb idea that takes time away from more important things... he can still be goated into a theoretical discussion. :)
Trapp
Wolf
Drew
Jeremy

Manufacturing:
Trapp
Parish
Coverdill
Pre-Pack Machining

Electronics and computers:
Wolf
Elboco
Jack

Software:
Wolf

FEA:
Don
Brad
OnShape.com
SimScale.com
Prabhu

Welding:
James.Brownfield@ColdwellBanker.com
Cy
Parish

Materials:
MetalsDepot.com
ModernImports.com
Kiszka
MacksRecycling.com

The I-Beam is in.

The main new load bearing member is in the car permanently.  From a Civil Engineers perspective, "This is so cute," as the beam is 2.33"W x 3"T.  I have no idea why they make one so small, but it works for us! 
Positioning the I-Beam into the frame for welding.

You can see at the top end of the I-Beam that we added a plate.  The plate allowed us to do the difficult welds out of the car, and better match the thickness of the car sheetmetal to ease the welding in the car.  The in-car weld goes around all 4 sides of the plate.  Thank you to Keith for the insight in making the engineered system more manufacturable.

James welding in the I-beam
We caught James Brownfield in action and had a bit of fun with him.  No matter how many times we told him that the welding helmet would darken automatically he obviously has been using the traditional welder mask all his life and would twitch his head to flip the helmet up and down for each weld.  Constantly expanding his horizons, I learned during this visit that in addition to being a precision instrument maker, that he also does real estate brokering.  James.Brownfield@ColdwellBanker.com
As opposed to my plan for some coarse and messy good old fashioned stick welding, James preferred TIG and they are much prettier than I could ever do.

Z-Bar battery frame with doubler plates tacked in position.
 I was not convinced the welds on the Z-Bar would hold as predicted and James had the suggestion of adding doubler plates to the sides spanning the welds.  We welded the joints, ground them flat, and then TIG welded the doubler plates all-around.  The image also shows the addition of the spanner angle iron.  These angle parts serve two functions, they significantly stiffen the Z-bars for side loading and they provide the lower attachment points for for the battery boxes.

Z-bar doubler plates
I-beam in, front battery boxes in place.
In the above image you can see the water pump and vacuum pump resting on the I-beam.  We are now int he process of determining the exact placement of the pumps.  They will hang from the underside of the I-beam,  Above the beam will be the DMOC controller and the 12V battery.

Friday, April 7, 2017

Battery frame progress

The I-Beam front support member of the battery frame was fitted last night.  Hopefully it warms up enough today to put some paint on it so we can weld it in fully along with the rest of the frame soon.

A donation to the cause a friend has shared a cut-off saw.  A little maintenance, fresh wires, oil, and a fresh blade made it cut like butter!  Manufactured in 1941! We found the thread standards in 1941 must not quite have matched today's standards when replacing some of the frame bolts.

I-beam test fit.  It will be welded at both ends to the main car frame.  It will have the battery frame set on top of it and the DMOC.  The A/C compressor, water pumps, vacuum pump, and steering pump will be hung from it.
Battery box with side holes for the battery compression rods.

Battery box with lower holes for battery and battery frame attachment.

Monday, March 27, 2017

Battery boxes and support frame build.

We ordered metal and have been working to get the boxes made and frame complete.  This has been a productive weekend.
If you want more explanation just ask in the comments, the pictures seem to be enough for most folks.

Mock-up of battery boxes

Donation of a cut-off saw to the project.  Blades are on order, apparently the standard size used in 1941 is not standard today.














  
Battery frame pieces cut to shape.
Taped together for a test fit.












































Tack weld together.  OH, AND another donation of an old stick welder!           


Battery boxes welded up.  10 of 11 modules shown, 11 modules do fit, we checked.  Next step here to drill 13 holes for holding the batteries in place and paint orange.
Firewall plate fit check, a bit more cutting and grinding to go on this plate.
The A/C drain hose will come out where the two holes in the middle are, and The right corner will be removed to allow for the re-installation of the shifter.
Last test fit before welding the frame in place.
If you look near the top center of the picture you can just see the corner of the license plates that arrived last week.  $18/year!
AND YES! The hood still closes with a full inch to spare.

Everything fits, we will get some pictures of the complete battery frame after the firewall plate is trimmed and front I-beam is welded in. 


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 (https://cad.onshape.com/), using the split surface tool in OnShape such that uniform loads could be applied to the z-bars, importing the OnShape model into (https://www.simscale.com/), 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.


Sunday, February 12, 2017

More on the battery box calculations

We have been doing some structural calculations.
The boxes each have 11 modules @ 8lbs ea.  therefore ~110 lb per battery box
The DMOC645 is ~ 60lb
Therefore ~300lb for the system.
We have looked online and consulted others with our best standard maximum loading guess as:
3g V+ 2g Lat + 1g Long
2g Lat + 2g brake on 20% grade  We live more than 50miles from ANY grade therefore we are not worried about the 2g down 20% grade...But it was surprising to us that the brakes do not exert more than a 1g load at full capability.
The frame will be made from A36 steel:
minimum yield strength of 36,000 psi (250 MPa)
ultimate tensile strength of 58,000–80,000 psi (400–550 MPa).
Based on these numbers we will design daily usage to  3-2-1.  Our safety factor will therefore be 1.8 to failure and likely due to impact of some sort.
EVERYONE likes pretty pictures:  The frame was designed in CREO 2, cleaned in OnShapeCad, and analyzed in SimScale.  The tubes are hollow 0.065" thick and 1" square.  The I-beam is 3"x2" and the smallest we can get but cheaper than C-Channel and Square tube of the same modulus.  The mesh is quad and tet.

1g Vertical Stress Field

1g Vertical Displacement Field
Nothing to see here, load is well under the 250MPa yield stress.

Unfortunately the scale is in black and does not show.  I set the max to 250MPA.  The max displacement is 2mm in the 3g loads.














Interesting only until you look at the actual value of the red section.  The displacement is a fraction of a millimeter.  The system does not react symmetrically because the area where the near tube connects to the right plate is in front of the exhaust tunnel and therefore not supported as rigidly.  I did do a check on the system where I fixed the tunnel area and the system did behave symmetrically.



3g Vertical, 2g Lateral, 1g Long. Stress Field

3g Vertical, 2g Lateral, 1g Long. Displacement Field

5g Vertical, 5g Lateral, 5g Long. Stress Field




































From the analysis, there will be local yielding under a 5g load, but the maximum tensile strength will not be exceeded.  A crash would likely apply more than 5g to the system, but then significant other deformation of the frame has occurred at that point too.


5g Vertical, 5g Lateral, 5g Long. Displacement Field

My hand calculations are on the same order of magnitude, SO please point out my errors if you see them.

  The thickness of the rear plate was 0.25", I have rerun the results, there are not surprises.  I will run a 0.125" plate instead.

NEXT STEP ORDER MATERIAL!

Tuesday, January 31, 2017

Battery boxes have slowed us way down.

We are currently working to ensure the I-beam and square tubes will be sufficient to hold the batteries, DMOC and other electronics.  ~300 pounds
Ortho view driver's side
Driver's side
Top view