Well, I broke it.

[pugslyyy]

Yes and history (ancient and modern) has shown us that in order for that 'anyone' to build it strong enough they first had to build one or two that collapsed.
.

Oh yes, and as always: Light, Strong, Inexpensive. Pick any two you want.

Interestingly enough, the first cast iron bridge (1779) still stands today because it was so massively overbuilt. (They build it the same way you would build a timber bridge except they used iron)

 

[GR8ADV]

They build it the same way you would build a timber bridge except they used iron

Yes, you are spot on. This truss design was a tried an tested proven design.
.
My one and only point is really just a word or two of caution. We should all be very careful when modifying members in a design, or loading the vehicle in a manner that is outside of the parameters for which it was designed. Extending a member or the wheelbase is potentially dangerous. Loading the vehicle in a way that it was not intended is potentially dangerous. Most folks look at the vehicle load limit and that is all. It is just not that simple. For example I think Toyota did not account for people hanging crap off the back of the Tacoma's in the early 2000's with the design of the Tacoma's. The result is, that when people hung heavy bumpers/spares etc behind the axle on the rear they broke frames. I expect the reason for FUSO saying that this vehicle is not for off road use (according to MOG) is that off road can cause loading situations such as impact loading (a multiplying factor added to the actual load to account for the load bouncing) is something that that they chose not to design for. So as MOG points out, one must accommodate for this somehow or bad things will happen.
.
The manufacturers now do most of their testing via computer models. Unfortunately we do not have the benefit of that. Thus we test them in the field. Your first test is now complete. GL with the fix. Get some expert advice, and I look fwd to this baby getting back together and out in the field where it belongs! k

 

[westyss]

Amen to that !
The poor Fuso gets a much-maligned frame here on the Expo Portal.
In my research all the tens of thousands of commercial Fusos on the road seem to have no issues with sub-par frames unless they have been abused (snow plows) or rusted (snow plows, hauling corrosive materials & rust belt trucks).
Are they as strong as a comparable Iveco (1st hand knowledge), or an Isuzu (specs), IMO no. BUT are they as strong as they need to be for their designed parameters, IMO yes.
Are they a Mercedes Unimog or 1017 designed with a 3 or 4 point subframe in mine, no.
Once you start operating anything outside it's designed parameters, then the item is not at fault, it is the new designer/operator.
I’ve had my Fuso at 20%+ over GVW with no problems. Did I do that off-road, no. Did I do that long term, no. Would I make that a routine operation, no. Did I take extra precautions operating over the GVW, yes. So the burden of something going wrong was on me, not Mitsubishi.

Just to stir the pot a bit, I posted about the Turtle Ford frame break a while back but little seems to be said about that, seems all frames will break if abused or not, too many variables in the equation to define why. So, yes the Fuso frame is getting a bit of a rep on expo but it appears that it isnt limited to just these trucks.
All I know is that you need to get it fixed up some how, and looks like a sound plan is in place to get that sucker back on the road!

 

[pugslyyy]

The manufacturers now do most of their testing via computer models. Unfortunately we do not have the benefit of that. Thus we test them in the field. Your first test is now complete. GL with the fix. Get some expert advice, and I look fwd to this baby getting back together and out in the field where it belongs! k

You mean like this?

 

[GR8ADV]

You mean like this?

View attachment 236515

What program is that? In the hands of the right person this could be way cool.
.
Very interesting. So what stresses and loading are we looking at? fixed ends with spring supports or?

Thanks. Now I am really interested. Haha

 

[pugslyyy]

What program is that? In the hands of the right person this could be way cool.
.
Very interesting. So what stresses and loading are we looking at? fixed ends with spring supports or?

Thanks. Now I am really interested. Haha

This is Autodesk Inventor Pro - it has a stress analysis module that is pretty good. I wouldn't use it for absolute prediction (i.e. part will fail at XXXXX pounds) but I like it as a way to evaluate a model and find where the weak points / stress risers are.

I'm just using a generic HSLA steel in this model - close enough to what I will use to give me useful data even though it won't be exact. In the one I attached I'm using point loads of 5000 pounds in each corner and transferring it down through the crossmember gussets that the leaf springs will be bolted to.

The distortion of the frame shown is highly amplified... the actual frame deflection would be much harder to see. There is a slight bulging between the two main crossmembers - I've considered boxing the frame for 6-8" there and probably will (it's where the bumps stops will be)

 

[SkiFreak]

What program is that?

Any of the good engineering CAD applications will include stress analysis functionality (Inventor, Solidworks, Rhino etc.)
Applications like SketchUp, that many people seem to use, is primarily an architectural CAD program. It's probably about choosing the right tool for the job at hand...

 

[pugslyyy]

Any of the good engineering CAD applications will include stress analysis functionality (Inventor, Solidworks, Rhino etc.)
Applications like SketchUp, that many people seem to use, is primarily an architectural CAD program. It's probably about choosing the right tool for the job at hand...

It's been an EXTREMELY steep learning curve, but I'm able to do things a lot more easily in it than I used to!

 

[SkiFreak]

It's been an EXTREMELY steep learning curve

I feel your pain, but agree that it's worth the effort.

 

[GR8ADV]

So pugs what stresses are we looking at in the pic. I can't figure it out. Thx.

 

[mog]

I expect the reason for FUSO saying that this vehicle is not for off road use (according to MOG) is that off road ....

Not my quote or thought (see pugslyyy's post). I have not see Mitsubishi say the Fuso is not for off-road and I have see advertising from them, with the Fuso in an 'off-road' situations working as designed.
Mine has been and will be off road.
-
-

You guys would certainly know better than I, but might any of the holes be for stress relief or to calibrate stiffness under torsion?

I believe that John's point is as Mitsubishi designed the Fuso's frame (thickness, material, height, width, etc) they factored in a swiss-cheese amount of holes. Since the frame has some flex certainly they did the calculations as to the effect of those holes.
I would think now with Robinson Fuso getting a completely new engineered frame (thicker, stronger, able to leap tall buildings in a single bound) that is a mute point.
I would suspect that the area (joint) were the uber-frame joints the Fuso's stock S-frame now will be an area of concern (strong meets normal). Certainly not a place you would want a catastrophic failure.

 

[pugslyyy]

So pugs what stresses are we looking at in the pic. I can't figure it out. Thx.

linear vertical stresses, pushing down at the corners and up at the two main crossmembers. each arrow is set for 5,000 pounds so pressing down with 20,000 pounds and up with 20,000 pounds

 

[mog]

View attachment 236515

Interesting.
LoRoad just posted Bliss Mobil's stress testing on his subframe (subframe, not main truck frame) over HERE

 

[GR8ADV]

linear vertical stresses, pushing down at the corners and up at the two main crossmembers. each arrow is set for 5,000 pounds so pressing down with 20,000 pounds and up with 20,000 pounds

Well that would be the applied loading... What are these results we are seeing. They do not appear to be bending or shear stresses. Deflection?? Not questioning, just have questions.

 

[pugslyyy]

Not my quote or thought (see pugslyyy's post). I have not see Mitsubishi say the Fuso is not for off-road and I have see advertising from them, with the Fuso in an 'off-road' situations working as designed.
Mine has been and will be off road.
-
-

Next time you are in the dealership, take a look at the caution sticker on the interior of the driver's door!