Ramp Materials

[Matt Gardner]

My team is VERY, VERY new, so any input from a veteran team would be appreciated. We have designed our ramp system, but do not know what material to build it out of. We have an aluminium fram completed but need a material to mount on it to support the robots we will lift. Weight is a slight issue, we have considered:

- Lexan
- 1/4 inch plywood
- Expanded Aluminium
- Expanded Steel

Any input on our ideas and especially NEW SUGGESTIONS would be wonderful, thanks...

[burkechrs1]

Steel is a definate no, and lexan can get up there in weight as well. Aluminum can be heavy but you could also cheese it if need be. Plywood can be heavy too especially in sheets for a ramp. Your best bet if you can get it would probably be diamond plate. It isnt that heavy, and it's alos strong. We're using carbon fiber with honeycomb filling but that is a little pricey. If you have the money i say do that.

[Hunter]

Originally Posted by Matt Gardner

My team is VERY, VERY new, so any input from a veteran team would be appreciated. We have designed our ramp system, but do not know what material to build it out of. We have an aluminium fram completed but need a material to mount on it to support the robots we will lift. Weight is a slight issue, we have considered:

- Lexan
- 1/4 inch plywood
- Expanded Aluminium
- Expanded Steel

Any input on our ideas and especially NEW SUGGESTIONS would be wonderful, thanks...

Plywood would probably be your best option, without the ability to purchase high priced composites or honey comb paneling, or fancy sheet metal working, plywood will provide your best strength and rigidity for the weight, and is very simple to work with. Typical softwood plywood has density per unit area around 13%-14% that of aluminum, and birch plywood around 23% that of aluminum. Because of the decreased density your moment of inertia about the thickness will be much greater for a similar weight and will provide much higher strength. Also plywood is dirt cheap when compared with aluminum so it will be much easier to keep spares on hand.

[Dad1279]

1279 has used alumalite: https://www.harborsales.net/fullshee...Faced%20Panels

Light & easy to cut.

[MattLi]

Using: A semicircircular wheel, a TON of aluminum fencing, and an axle (aluminum shaft).

Problems: Danger to robots (we don't know if will may capsize with two robots)

[Madison]

Originally Posted by Dad1279

1279 has used alumalite: https://www.harborsales.net/fullshee...Faced%20Panels

Light & easy to cut.

Out of curiosity, what's the weight per square foot for a 1/4" or 3/8" thick piece? I wonder if it's worth our time to investigate replacing our corrugated polycabonate with this.

[Matt Gardner]

From what I've researched (it does not seem that common) it is .375 lb./sq. ft. (for a 6mm thick piece) Our team figures our ramp covering would weigh only 10 lb. if using it (awesome). My only problem is that I cannot find many teams that have used this material and do not know how well it stands up to the weight of a robot. (Moreover, it comes in a variety of colours, also awesome)

[Doug G]

We're using a carbon fiber / foam sandwich that we made ourselves. Each 40" x 38" panel weighs around 4-5 lbs. We then have an aluminum kickstand and track that sits underneath the ramp with a FP/BaneBot winch to raise the kickstand. With the motor/winch/kickstand and ramp it comes to 10 lbs per ramp.

[MrForbes]

Originally Posted by Matt Gardner

From what I've researched (it does not seem that common) it is .375 lb./sq. ft. (for a 6mm thick piece) Our team figures our ramp covering would weigh only 10 lb. if using it (awesome). My only problem is that I cannot find many teams that have used this material and do not know how well it stands up to the weight of a robot. (Moreover, it comes in a variety of colours, also awesome)

It looks like Alumalite is a sign material, two thin sheets of aluminum with a corrugated plastic core. I didn't find any specs on how strong it is in bending in a quick google search. My wild guess is that it might work as a ramp material if you can support it well, perhaps every 6 inches or so (width). But it probably dents rather easily if you apply a concentrated load to it, and might buckle. Hard to say without more info....

[Matt Gardner]

I realize the normal application, but it's not used for those little wimpy signs, either. If you look here:

http://www.signboards.com/Applications/index.asp

you can see the type of signs that its being used to build. I figure these need to be strong and impact-resistant just because they are always outside...

What I really need is feedback from someone who's used Alumalite in the past...anyone?

[MrForbes]

Originally Posted by Matt Gardner

I figure these need to be strong and impact-resistant just because they are always outside...

If those signs can stand up to the occasional flying robot, they should be able work as ramp material?

I agree, you do need some input from someone who has played with the material, or used it on a robot or something. Since it's not a structral material, there seems to be no or very little structural info about it available.

If you can estimate the thickness of the aluminum layers, you could calculate the moment of inertia and estimate the bending strength under static loading conditions. As an example, I just calculated the stress due to bending, assuming a 6" wide ramp, 3 feet long, 100 lbs load at the center. Material .25" thick, each aluminum face 0.020" thick. The maximum bending stress would be about 70,000 psi, which is about four times the yield stress of soft aluminum, and about twice the yield stress of typical heat treated aluminum alloys.

So, you would need to provide support for the ramp about every foot of length to make it strong enough to adequately support a robot....is my guess....

[Dan Zollman]

I can't really find anything about Alumalite used for something other than signs. Since it would be used in big sheets outdoors, it must be made to hold up against wind and rain. But doesn't that mean that bending isn't the force it needs to resist, since wind and rain probably hits the sign evenly? In addition, signs can have a lot of framing and support behind the surface, so it would probably have short distances between supports.
Impact is probably the only thing it's designed to resist, while I don't think it would work for a robot like 1712's since we need to save weight with as great a distance between supports as possible.

I could be wrong about all of that, but I'm just trying to figure this out. It just doesn't seem to me that Alumalite is the right kind of material for a platform/ramp surface.

[Matt Gardner]

With the frame we are building at the moment we have supports about a foot apart, I do believe... I have to check up on that tomorrow...It's true that what really matters is what kind of weight it can support, mostly I'm just wishfully thinking. I'm trying to contact the company again tomorrow to see if I can find out more information. As for impacts, we hopefully won't have any, we want smooth driving up the ramp, and smooth driving off. We are using a totally different material for the sides as well, a much stronger one... and we're hoping no manipulators smash into our ramps, either...(again with the wishful thinking)

[DonRotolo]

Team 1676 is using a welded aluminum frame of 1" square stock with 1/16" wall, covered by 1/2" steel hardware cloth (looks like giant window screen with 1/2" holes) that is 'welded' at the intersections. The approx. 30" x 35" ramp weighs about 5 pounds.

Don

[Tapoore]

Originally Posted by Matt Gardner

With the frame we are building at the moment we have supports about a foot apart, I do believe... I have to check up on that tomorrow...It's true that what really matters is what kind of weight it can support, mostly I'm just wishfully thinking. I'm trying to contact the company again tomorrow to see if I can find out more information. As for impacts, we hopefully won't have any, we want smooth driving up the ramp, and smooth driving off. We are using a totally different material for the sides as well, a much stronger one... and we're hoping no manipulators smash into our ramps, either...(again with the wishful thinking)

We are going to use Alumilite for at least part of our lifters. The stuff seems REALLY strong. I believe we are planning to use it unsupported across a section about 2' X 3'. I don't know if the stuff comes in different thicknesses, but ours is about 3/8" thick. We chose it because it is for the ramp that leads up to out lifters, and it needs to be almost indestructible because of the impact from robots driving into it.

The only thing we don't like about it is the price. It is $200 for a 4' X 8' piece!