Does anyone make skid plates for our trucks that are engineered for better strength to weight? A flat plate is not a very strong shape, but most skid plates seem to be just a flat plate with bent sides. For example, take a sheet of paper and try to bend it. Now fold it in an accordion pattern and try to bend it across the folds. The ARB skid plate is along the lines of what I'm thinking since it's pressed and folded, but it's known to bend easily, so it may not be the best design. It's 3mm steel (0.118, or about 63% as thick as the standard 3/16 heavy duty steel plates), which should be enough with sufficient reinforcement.
I think it's generally preferred that skid plates be flat on the bottom so you don't get hung up on them. It's also preferred if the material facing down is slippery, like steel or even plastic (UHMW, for example, but HDPE is a cheaper option). And it needs to be thick enough (including backing material) not to be dented or punctured by sharp rocks. I think some skids, maybe for jeeps or FJs use a thin replaceable stainless sheet covering the skid, which may be made of Aluminum.
I haven't installed skid plates yet, but I imagine there would be space for reinforcement above a lot of the flat area without having to lower the plate and decrease ground clearance. For example, it looks like there's a lot of space between the transmission skid and the transmission pan, and some of that space could be used to give the plate structure.
An example would be welding parallel pieces of angle stock to the top side. The triangular sections that are formed would be many times stronger than a plain sheet, like accordion folded paper, and thinner stock could be used so overall weight is the same or decreased. I would make something like this myself, but unfortunately I don't know how to analyze the strength of a part (finite element would be good), and I don't have the equipment, skills, time, or money to fabricate something out of metal.
I'm thinking about doing a DIY gas tank skid. Since it doesn't get hot like the engine and exhaust, I can use materials other than metal with less risk of fire. It's big and flat, so it might benefit from some structure. It seems to be able to tolerate some dents, so if I mess up it wouldn't be ruined. The downside is that there's no space for additional thickness here without decreasing ground clearance, unlike some of the other skids.
Materials I'm considering are UHMW/HDPE, fiberglass, or even wood for stiffness, and a thin steel sheet for abrasion resistance. And I just remembered G10/FR4 which is basically what they use to make printed circuit boards. It's a fiberglass composite made under pressure, so the strength to weight is better than any fiberglass composite I could do at home.
McMaster-Carr
A 2ftx3ft 1/4" thick sheet is probably indestructible*, and it only weighs 15lbs by my calculations. I'm not sure how big the gas tank is, but probably not a lot more surface area than that. A thin sheet of steel would give it abrasion resistance without a lot of extra weight. G10 can be cut on a water jet or using abrasive tools (carbide or diamond) like you would use for glass or tile. I have an abrasive jigsaw blade that will cut it, but I don't know how it would handle 1/4" thick sheets.
*McMaster has material properties for it on their site. I would have to learn more about material properties to compare it to steel, but it looks like the tensile strength is higher than some grades of steel. Definitely higher than 5052-0 aluminum. If you press a sheet of it into the corner of a rock, the part closest to the rock is in compression and the part farthest from the rock is in tension. Since it's thicker than steel for the same weight, I think it has an advantage, but I'm not sure.
Higher grades of aluminum in skid plates would be nice, too, but they would probably get expensive. Jeep guys seem to be using some 6061 T6 aluminum to replace steel, and it's a lot stronger than 5052-0 aluminum, like double the strength.
I think it's generally preferred that skid plates be flat on the bottom so you don't get hung up on them. It's also preferred if the material facing down is slippery, like steel or even plastic (UHMW, for example, but HDPE is a cheaper option). And it needs to be thick enough (including backing material) not to be dented or punctured by sharp rocks. I think some skids, maybe for jeeps or FJs use a thin replaceable stainless sheet covering the skid, which may be made of Aluminum.
I haven't installed skid plates yet, but I imagine there would be space for reinforcement above a lot of the flat area without having to lower the plate and decrease ground clearance. For example, it looks like there's a lot of space between the transmission skid and the transmission pan, and some of that space could be used to give the plate structure.
An example would be welding parallel pieces of angle stock to the top side. The triangular sections that are formed would be many times stronger than a plain sheet, like accordion folded paper, and thinner stock could be used so overall weight is the same or decreased. I would make something like this myself, but unfortunately I don't know how to analyze the strength of a part (finite element would be good), and I don't have the equipment, skills, time, or money to fabricate something out of metal.
I'm thinking about doing a DIY gas tank skid. Since it doesn't get hot like the engine and exhaust, I can use materials other than metal with less risk of fire. It's big and flat, so it might benefit from some structure. It seems to be able to tolerate some dents, so if I mess up it wouldn't be ruined. The downside is that there's no space for additional thickness here without decreasing ground clearance, unlike some of the other skids.
Materials I'm considering are UHMW/HDPE, fiberglass, or even wood for stiffness, and a thin steel sheet for abrasion resistance. And I just remembered G10/FR4 which is basically what they use to make printed circuit boards. It's a fiberglass composite made under pressure, so the strength to weight is better than any fiberglass composite I could do at home.
McMaster-Carr
A 2ftx3ft 1/4" thick sheet is probably indestructible*, and it only weighs 15lbs by my calculations. I'm not sure how big the gas tank is, but probably not a lot more surface area than that. A thin sheet of steel would give it abrasion resistance without a lot of extra weight. G10 can be cut on a water jet or using abrasive tools (carbide or diamond) like you would use for glass or tile. I have an abrasive jigsaw blade that will cut it, but I don't know how it would handle 1/4" thick sheets.
*McMaster has material properties for it on their site. I would have to learn more about material properties to compare it to steel, but it looks like the tensile strength is higher than some grades of steel. Definitely higher than 5052-0 aluminum. If you press a sheet of it into the corner of a rock, the part closest to the rock is in compression and the part farthest from the rock is in tension. Since it's thicker than steel for the same weight, I think it has an advantage, but I'm not sure.
Higher grades of aluminum in skid plates would be nice, too, but they would probably get expensive. Jeep guys seem to be using some 6061 T6 aluminum to replace steel, and it's a lot stronger than 5052-0 aluminum, like double the strength.
