Something I was not able to search on the NET.

It depends on how well they are laminated!

If your are talking about plywood and the two pieces are laminated using the same method that was used in their original manufacture then the result will be as strong as the 'h' mm ply (assuming correct orientation of plies...and that the plies are of consistent material ...e.g. it's not decorative faced ply).

In fact generally laminating timber will give a stronger result as the imperfections and grain can be 'averaged out' (for want of a better expression)

Two sheets of steel laminated together with blu-tac will not be as strong as the single sheet.

Thanks for your reply !

If I use rivetting or a plastic or fiber to join the metallic sheets will the joint be strong enough so as to be used under heavy cyclic stresses and vertical loading patterns.

Glued, laminated beams ("Glue-lams") are interesting to the designers of timber structures. Significant strength and rigidity can be obtained by laminating timber pieces together, and the limits of size imposed by making a structural timber element from a single tree are absent.

A building extension at these co-ordinates has two of these in softwood, 350 x 175 x 6500mm, as structural elements. How the builder managed to install these at 4.5m above ground level using only 3 people and no crane tackle is a thing of great wonder. They have been left uncovered and suitably decorated as both an architectural detail and a tribute to his ingenuity.

Hi PW

Got a pic?

I recently saw the 'gridshell' building at the Weald and Downland Open air museum in Sussex...Brilliant

(as mentioned on 'Grand Designs') ..a new take on an oak frame using a grid of thin laths ...execllent website...just google 'em if you want a butchers.

Del

Abhinav,

The strength of the laminated sheets for sure increases but there would be limitations of using the system or laminated sheets of metal. THe reson is bonding.

Plastic rivets might not help you for the bonding. Can you briefout where you intend to use the concept.

For making automobile frames we require sheets of 4 or 5 mm width(Say).

So is it possible to achive better physical properties by taking thinner sheets and laminating them.

If we look at the frame of a Truck ( generally a c - channel) , the sheet metal used is about 4 to 7 mm thick depending upon the payload of the truck.

If we can achive similar properties by using thinner sheets be laminating them together is what I intend to finde out.

This was a typical construction technique for increasing the strength of I beams. You rivet 1 or more continuous strips to the top and bottom flanges. But again, you need an engineer that is a specialist in structural or mechanical.

Check out Zyplex, a laminated panel produced by DOFASCO in Hamilton, Ontario.

see <www.zyplex.com>

Dofasco uses presses to laminate a proprietary core with sheets of light gauge steel, you might contact Zyplex and get all the structural and material properties.

I believe it's also patented, and you might search on the USPO for the patent.

Good luck

The joining of the layers is critical. If it slides then doubling the thickness only doubles the capacity under bending loads. But if they are intimately joined then with doubling the material I believe they will have an increase in stiffness 4 fold, since it is the moment of inertia of the cross sectional area. (But I am an EE, you need a structural or mechanical eng. for a real opinion, and this is a distant memory from school days (or is it daze?)).

Multiple spot welds correctly positioned would do the trick.

For structural automotive use I would use the thicker material, it will be more reliable and cheaper in the long run, even if you need to upgrade bending/cutting equipment.

The flex and vibration could easilly cause a poorly designed laminated part to fail (conversely, a well designed spot welded box section would be better!)

I don't suppose anyone has ever upgraded their equipment and found they didn't use it.

Laminated metal sheeting and composite laminated materials have been used in the construction of aircraft for some time now. There are a myriad of techniques that are used, some of them being closely guarded secrets.

I would suggest having a look at some of the older more common methods that are used in aviation as they are more than likely already tried anything you can think of..

One question though, do you need to use metal? There are many composite materials that are stronger, lighter and cheaper than metal so would probably be a good idea to have a look at what else may be used for the construction.

I saw an experiment that was carried out recently, using the dies form the metal presses that had been used to construct sheet metal components for cars. With very little modification they use them to manufacture plastic equivalents to the metal components. The result was a component that was several time stronger, a fraction of the weight, cost less to produce, took no longer to manufacture, was not susceptible to corrosion and could be manufactured with minimal modifications to the existing equipment.

Can you plese direct me to that report , it would be of great healp for me.I also belive composites can be used in many more applications in the vehicle than is being used today.

Also where to look for Laminated metal sheeting and composite laminated materials studies that have sufficient material online for study.

Regards,

Abhinav

Unless welding is done properly, metal may crystalize and be more succeptable to cracks and fractures. You are better off starting with the proper guage metal than trying to build up to specifications. The other possibility is riveting and banding the steel such as truck springs.

The bigger issue in making a laminate in my mind is the corrosion issues that you will get between the layers. In norhtern or seaside areas where there is road and sea salt, that laminate will be a mess in no time. Go with the thicker gauge.

My $0.02

Here are my answers to your question based on my own experience with laminated materials. If you are asking if two 3mm sheets laminated together are stronger than a 6mm sheet ... the answer as far as I know is ... no. I'm guessing you were hoping that two 2mm sheets laminated together would be equal in strength to a 5mm solid sheet. Or something along that line of reasoning. Again ... to my knowledge ... no.

The advantaged of the laminated metallic materials that I have used, came in the area of lighter weight, for the same stiffness. But for that, you sacrificed thickness. Also, for that you need a composite laminate, i.e. two sheets of very thin metal, sandwiching a thicker sheet of some other non-metallic material. It's the extra distance between the two outer layers, and the absolute bond between the materials which gives you strength (stiffness) that is equal to a single sheet of heavier sheet metal. So you end up with 1) Stiffer, 2) Lighter, 3) Thicker.

To my knowledge, you can't get stiffer, but thinner. Not in the thicknesses that you are referring to, anyway. Or at least without relying on extremely advanced material technologies (aeronautic) such as were mentioned in the post above. And I'm guessing these types of things are beyond your budgets.