Stress Test on Front Crash Bars

BMalm

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I removed the front crash bars to make space for me tires and tire offset. I was getting rubbing with the zero offset so I purchased some aftermarket crash bars that fit nicely and look really good. I was curious how these new beams stacked up against the OEM ones. So I ran an FEA (Finite Element Analysis) on them so see which are stronger.

Legal.....I have to say this for legal reasons. 1.) I do not work for Ford or any aftermarket company. I did this purely on my own as a check. 2.) I do to take ANY responsibility for other peoples actions and do not make any recommendations with the information I'm supplying here. This is purely something to discuss and that is all. 3.) I do not have actual data and real world loads to apply to the FEA that I show here. There are many factors that are taken in this design. I don't know or have the data I would need to represent these in a real world situation. 4.) The crash bars are likely designed to work with the structure of the truck and predicted impacts.

I don't want to get sued by anyone for doing this, I just wanted to show the difference between the beam that comes with the truck, a modified version of that same beam, and an aftermarket beam that I purchased.

The first test run I did was with the beam that comes on the truck. The tube seamed rather light and is very thin material. Looks to be about 2mm thick wall. I applied loads to the entire back side of the tube that sticks out and kept adjusting the load until it passes a typical static stress analysis. I ended up coming up with a static load of 1150 lbs, which put the beam right on the edge of passing a load test. This is just a static test, not a dynamic test.

The second test I ran was with a modified crash bar or tube. I've seen a lot of people cut the tube back by about half the tube width. So that is what I did. I results were way worse which I expected. By removing the front side of the tube, you are removing a lot of the tube structural strength.
The results I got were complete failure at 1150lbs. I was only able to get it to pass at around 500ls which is a bit less than half.

The third run I did was with the aftermarket beam (I don't want to say who again for legal reasons). This beam was much narrower and cuts back enough to clear the tires. The beam were ALOT heavier. The wall thickness was almost double that of the OEM beam. There was also a middle rib that really helped add support. The results were pretty surprising. I was worried because the beam was a lot narrower that would be an issue but it wasn't These beams passed the load at 1150lbs by almost double. I was able to increase the load on these beams to 2000 lbs before they started to approach the danger zone. So by simple loading, it seems that the aftermarket beams were better than the other two.

Again, please understand that I do not recommended changing or altering your vehicle in any fashion. But I would say that it is defiantly safer to put an aftermarket beam in over modifying or removing the beams all together. Any engineer would recommend not removing or moding the OEM parts at all.

Take this for what it's worth. I thought the results were pretty interesting. And please don't make decisions based on what I have shown here. Your car or truck is your responsibility, and I take no responsibility for decisions you made from a web forum. I don't want anyone to get hurt or worse because of something I posted on the internet.

Aftermarket.jpg


Current Tube Mod 1.jpg


Current Tube.jpg
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NotBudule

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I removed the front crash bars to make space for me tires and tire offset. I was getting rubbing with the zero offset so I purchased some aftermarket crash bars that fit nicely and look really good. I was curious how these new beams stacked up against the OEM ones. So I ran an FEA (Finite Element Analysis) on them so see which are stronger.

Legal.....I have to say this for legal reasons. 1.) I do not work for Ford or any aftermarket company. I did this purely on my own as a check. 2.) I do to take ANY responsibility for other peoples actions and do not make any recommendations with the information I'm supplying here. This is purely something to discuss and that is all. 3.) I do not have actual data and real world loads to apply to the FEA that I show here. There are many factors that are taken in this design. I don't know or have the data I would need to represent these in a real world situation. 4.) The crash bars are likely designed to work with the structure of the truck and predicted impacts.

I don't want to get sued by anyone for doing this, I just wanted to show the difference between the beam that comes with the truck, a modified version of that same beam, and an aftermarket beam that I purchased.

The first test run I did was with the beam that comes on the truck. The tube seamed rather light and is very thin material. Looks to be about 2mm thick wall. I applied loads to the entire back side of the tube that sticks out and kept adjusting the load until it passes a typical static stress analysis. I ended up coming up with a static load of 1150 lbs, which put the beam right on the edge of passing a load test. This is just a static test, not a dynamic test.

The second test I ran was with a modified crash bar or tube. I've seen a lot of people cut the tube back by about half the tube width. So that is what I did. I results were way worse which I expected. By removing the front side of the tube, you are removing a lot of the tube structural strength.
The results I got were complete failure at 1150lbs. I was only able to get it to pass at around 500ls which is a bit less than half.

The third run I did was with the aftermarket beam (I don't want to say who again for legal reasons). This beam was much narrower and cuts back enough to clear the tires. The beam were ALOT heavier. The wall thickness was almost double that of the OEM beam. There was also a middle rib that really helped add support. The results were pretty surprising. I was worried because the beam was a lot narrower that would be an issue but it wasn't These beams passed the load at 1150lbs by almost double. I was able to increase the load on these beams to 2000 lbs before they started to approach the danger zone. So by simple loading, it seems that the aftermarket beams were better than the other two.

Again, please understand that I do not recommended changing or altering your vehicle in any fashion. But I would say that it is defiantly safer to put an aftermarket beam in over modifying or removing the beams all together. Any engineer would recommend not removing or moding the OEM parts at all.

Take this for what it's worth. I thought the results were pretty interesting. And please don't make decisions based on what I have shown here. Your car or truck is your responsibility, and I take no responsibility for decisions you made from a web forum. I don't want anyone to get hurt or worse because of something I posted on the internet.

Aftermarket.jpg


Current Tube Mod 1.jpg


Current Tube.jpg
So , TLDR , but your saying throw away unneeded factory crapbars and go crazy with wheels and tires ? I LIKE IT !!! And kudos for going out on a limb and verifying I can ditch those DAMN BARS !!!

I kid , I kid , pretty detailed analysis methinks , I wouldn't toss them, but I'd be ok with the the ones that let me creep up a size or 2 in the near future... BUT , I ride alone mostly , and would keep old ones in case I trade or sell , new owner should be made aware for my piece of mind...
 

jblc

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I have a few hesitations with your results. At a first basic question, what materials and parameters were you modeling with?

1) Dynamic analysis is what's really important here though, since deformation includes other effects that aren't well-behaving in the classical sense: buckling, heat dissipation during impact that affects strength, etc. This is quite complex and can't be captured with simple CAD FEA...so it's unclear if your results mean anything in the real world.

2) This isn't super surprising: strength is related to the area cross-section moment, even removal of a slight bit of material far from the bend axis/plane will make a large difference, since that material's moment contribution goes as radius squared.

Similarly, even a slight increase in thickness will yield large improvements -- or slightly increasing size.
 
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D Fresh

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Just want to clarify.

This was not actually tested, just a computer model?

While it's good to know we all would have guessed that by simply looking at them.

Some actual destructive testing would be more helpful. Albeit more expensive.
 


Trigganometry

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I was going to touch on this too. It’s part of an assembly that is designed to absorb energy and distribute in a way that the cab stays intact.

But if that’s the only way to go bigger tires and no rub better to have something than nothing at all.
 

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Or buy a Raptor and let Ford delete it for you...
 

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Thanks Brian,

This is great and seems similar to some testing on my beams that someone shared with me earlier. This looks like the front beam with the force coming from the front of the truck, yes?

It would be interesting to see a similar FEA test on the rear beams with the force coming toward the ribs (the rears mount with their ribs facing the front beam’s ribs), as if the force was the tire being pushEd backward into the ribbed part of the beam.
 

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I removed the front crash bars to make space for me tires and tire offset. I was getting rubbing with the zero offset so I purchased some aftermarket crash bars that fit nicely and look really good. I was curious how these new beams stacked up against the OEM ones. So I ran an FEA (Finite Element Analysis) on them so see which are stronger.

Legal.....I have to say this for legal reasons. 1.) I do not work for Ford or any aftermarket company. I did this purely on my own as a check. 2.) I do to take ANY responsibility for other peoples actions and do not make any recommendations with the information I'm supplying here. This is purely something to discuss and that is all. 3.) I do not have actual data and real world loads to apply to the FEA that I show here. There are many factors that are taken in this design. I don't know or have the data I would need to represent these in a real world situation. 4.) The crash bars are likely designed to work with the structure of the truck and predicted impacts.

I don't want to get sued by anyone for doing this, I just wanted to show the difference between the beam that comes with the truck, a modified version of that same beam, and an aftermarket beam that I purchased.

The first test run I did was with the beam that comes on the truck. The tube seamed rather light and is very thin material. Looks to be about 2mm thick wall. I applied loads to the entire back side of the tube that sticks out and kept adjusting the load until it passes a typical static stress analysis. I ended up coming up with a static load of 1150 lbs, which put the beam right on the edge of passing a load test. This is just a static test, not a dynamic test.

The second test I ran was with a modified crash bar or tube. I've seen a lot of people cut the tube back by about half the tube width. So that is what I did. I results were way worse which I expected. By removing the front side of the tube, you are removing a lot of the tube structural strength.
The results I got were complete failure at 1150lbs. I was only able to get it to pass at around 500ls which is a bit less than half.

The third run I did was with the aftermarket beam (I don't want to say who again for legal reasons). This beam was much narrower and cuts back enough to clear the tires. The beam were ALOT heavier. The wall thickness was almost double that of the OEM beam. There was also a middle rib that really helped add support. The results were pretty surprising. I was worried because the beam was a lot narrower that would be an issue but it wasn't These beams passed the load at 1150lbs by almost double. I was able to increase the load on these beams to 2000 lbs before they started to approach the danger zone. So by simple loading, it seems that the aftermarket beams were better than the other two.

Again, please understand that I do not recommended changing or altering your vehicle in any fashion. But I would say that it is defiantly safer to put an aftermarket beam in over modifying or removing the beams all together. Any engineer would recommend not removing or moding the OEM parts at all.

Take this for what it's worth. I thought the results were pretty interesting. And please don't make decisions based on what I have shown here. Your car or truck is your responsibility, and I take no responsibility for decisions you made from a web forum. I don't want anyone to get hurt or worse because of something I posted on the internet.

Aftermarket.jpg


Current Tube Mod 1.jpg


Current Tube.jpg
HI Brian,

Having lead a Chassis Design Analysis area in Light Truck Engineering for quite a few years, I have to say Kudos for your analysis, but they mean very little in the world of Crash Analysis which in non liner, non static. Radious was the software at the time to do crash analysis. It took many hours on a Cray C90 super computer of which Ford had two of these water cooled super computers. I am afraid your effort, which are laudable, might misled folks on the affect on the crash pulse into the interior of the Ranger cab.

I am uncertain in the affect on the crash pulse into the cab from non OEM bars... I fear it may actually result in a non optimal result..

So this is not misinformation but does not present the conclusive data that is necessary.

What meshing program did you use? Where are your spc's? Where are your spring elements? The frame is not an SPC. Any fatal errors in your first Mesh?

Best,
Phil
 

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Does anyone actually know the purpose of the crash bars?
I would guess it's to turn the front of the tire inward so the back wouldn't crush the foot well but that is a wild ass guess from someone with no engineering training.
 

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Does anyone actually know the purpose of the crash bars?
I would guess it's to turn the front of the tire inward so the back wouldn't crush the foot well but that is a wild ass guess from someone with no engineering training.
Standard trucks with wimpy tires does not provide enough cushion so the bars are needed to resist crush...FAT 285s can take the hit so Ford deletes them for cost savings...right????
 
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BMalm

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OK folks, I do state several times that this was just a simple static load test to show the strength difference between the three beams. This does not represent a real world crash test and that a full dynamic analysis with all the real world data and a full working model would be needed to supply that. I don't have any of this info or models to do so. With that said this was just meant to be a fun little experiment.

So please understand that the info supplied above should be taken with a big grain of salt. And yes, this was a computer simulation only.
Thanks
 

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I'm waiting fort the day that the manager in charge of deleting features from new models deletes the crash bars as an unneccary cost item.
 

Jason B

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I'm waiting fort the day that the manager in charge of deleting features from new models deletes the crash bars as an unneccary cost item.
The National Highway Traffic Safety Administration might have a problem with that.
 

irv0735

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Stuff like this is cool. I know there are vocal folks on here around keeping the crash bars... But mine bent back from someone backing into the bumper on trail and now rubs tire at 80% turn on flat ground... It's coming out when the new bumper, suspension, wheels and tires go on.
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