CarBEN EV5 Full Sized Prototype Construction - 5 Seat Electric Car From Scratch

[NeilBlanchard]

The hatch door will be latched in the opening, and the rear doors will overlap at an angle and brace that plane.

[jakobnev]

I happend upon this episode of "How it's made" and it really reminded me of this thread:

http://www.youtube.com/watch?t=640&v=UFqw5MQ-4nA

Car factory of the (near) future perhaps?

[NeilBlanchard]

The foam in the airplane fuselage has a 10mm foam core? Wow, that is pretty thin.

[jjackstone]

IIRC Neil,

Each time the core thickness between the layers of composite doubles, the strength cubes. Just for an example, if the 10mm layup could handle 10 pounds of stress, then a 20mm thick layup should be able to handle a 1000 pounds(10 to the 3rd power) of stress. These are just made up numbers. No idea what these thicknesses can really handle. I do have a two foot long, twelve inch wide, 3/4" honeycomb core laminated with just glass that I can't even begin to bend by placing it over my knee.
JJ

[NeilBlanchard]

Well, the 5" thick sides and rocker panels will be über strong?

By the way, I got a quote on the Smart ForTwo windshield, wiper system, and the vent bezel at the base of the windshield where the wiper arms pivot - and the total cost is about $820. Not bad, really. The next major expense with be the fiberglass.

Does anybody have suggestions on where to find a *manual* steering system?

[sheepdog 44]

Current bid is $150, selling tomorrow at noon.
Copart

[freebeard]

Does anybody have suggestions on where to find a *manual* steering system?

https://www.google.com/search?q=dune+buggy+parts

[3-Wheeler]

Originally Posted by jjackstone

IIRC Neil,

Each time the core thickness between the layers of composite doubles, the strength cubes. Just for an example, if the 10mm layup could handle 10 pounds of stress, then a 20mm thick layup should be able to handle a 1000 pounds(10 to the 3rd power) of stress. These are just made up numbers. No idea what these thicknesses can really handle. I do have a two foot long, twelve inch wide, 3/4" honeycomb core laminated with just glass that I can't even begin to bend by placing it over my knee.
JJ

Hi Jack,

Actually for a "rectangle" shape in bending, when the thickness doubles, the strength goes up by four (T^2). This is for a material of solid section, i.e. one material, not a composite.

In the Machinery Handbook this is known as Z Section Modulus.

The theory is something like this:

1) When the section thickness doubles, there is twice as much material to take the load.
2) Since the thickness is now double, there is fiber strength that is twice as far from the neutral axis, and therefore twice as much strength based on that alone.
3) When you add 1) and 2) together, one ends up with four times the strength.

Now when talking composites, all this assumes that the "core" (foam) can handle the shear loads and/or compressive loads from the "skin" in the composite, without delaminating and/or buckling.

Composites modify the above listed Z-Section due to the single layer of glass on the thinner and thicker sections of foam, so the strength increase is not strictly defined by T^2 anymore. You can see that modeling composite structures is not an easy undertaking.

If one were talking about the torsional stiffness of a drive-shaft, then you are correct, that it goes up by the cube of the shaft diameter (D^3).

Hope this helps, Jim.

[NeilBlanchard]

Here's the Framingham Earth Day Festival web site:

Come Celebrate Earth Day 2013 At our 3rd Annual Festival! « Framingham Earth Day Framingham Earth Day

This is the Facebook page: https://www.facebook.com/FraminghamE...93192404113417

See you there, I hope!

[JethroBodine]

Neil, I'm thinking of coming down for the day and was wondering, since your place isn't too far from there, maybe a quick peek at your progress in person? Maybe? Pretty please with sugar on top?

I looked on Google maps for the location and found it on the Center Common off Edgell Rd just North of Rt 9. If I take part of the "One Gallon Challenge" route, it's about 135 miles one way. If I cut across lower NH it's about 111 miles. Good chance for some practice.