Designing hinges for strength

[alangbaker]

I realize this forum is more about the machining of things than the design of things, but...

Could anyone point me toward a reference for designing hinges for maximum strength? I'm working on something for my open wheel Formula F (Formula Ford with Honda Fit engines now allowed), and I'm envisioning a hinging mechanism which will carry all the load of one corner of the car, which I'd like to be as light as possible (of course), and what I'd like to know is how to choose the relative sizes of the pin and the lugs of a piano hinge style design.

• Would a lot of small lugs be better than a smaller number of larger ones?
• What should the relative sizes of the cross-sections be when considering shear stress on the pin and the various failure modes of the lug?
• Etc.

I'm fluent in Google, but because hinges are such a common consumer item, it's very difficult to find more technical sites that might have the kind of information I'm looking for.

 

[Billtodd]

I suspect you are talking about the suspension, so try looking up ball , rose , spherical joints and bearings

 

[alangbaker]

I suspect you are talking about the suspension, so try looking up ball , rose , spherical joints and bearings

I absolutely am talking about the suspension, and I know all about ball/rose/spherical joints and bearings.

But I'm trying to do something entirely new that needs a series of linear hinges.

 

[Erich]

Soooo, if you do a bad job of design, a failure can cause bodily harm to the driver and/or others on the track.
Not thinking you will get many takers here.
Either get a degree in mechanical engineering or pay one to design it for you.

 

[jaguar36]

You’ve provided very little information. So its hard to give any real advice. For your first question though, one big lug is more weight efficient than lots of small lugs. For your second, Lug sizing is pretty easy and there are many calculators out there.

Without any other info I’d say look at other designs for light weight, race cars and planes and see if you can find a similar design.

 

[alangbaker]

Soooo, if you do a bad job of design, a failure can cause bodily harm to the driver and/or others on the track.
Not thinking you will get many takers here.
Either get a degree in mechanical engineering or pay one to design it for you.

Dude, lighten up.

I'm not asking anyone to take responsibility for the design of anything.

I'm looking for someone who can point me towards a reference for doing the calculations.

I'm already using Onshape to run simulations on the structure and for the moment, even the basic concept seems viable. And that's just sizing the components for what feels right. But I can check von Mises stress, and safety factor in the materials I'm considering.





(Both of those images are assuming the full weight of the vehicle on a single corner at 2.5g. And the maximum deflection you're seeing is 2.245mm)

But somewhere out there, there is someone who's written something on the subject, and all I'm asking is if someone knows where that might be.

 

[Scruffy887]

Think about it long and hard. Cuz I do not want to be driving full send following a car shedding parts.
Ever decide to pit a lap early and see the car leading you scatter itself all over turn one? Yeah, saw it from pit out road.

 

[alangbaker]

You’ve provided very little information. So its hard to give any real advice. For your first question though, one big lug is more weight efficient than lots of small lugs. For your second, Lug sizing is pretty easy and there are many calculators out there.

Without any other info I’d say look at other designs for light weight, race cars and planes and see if you can find a similar design.

I appreciate the thoughts but if you have a simple hinge that is basically the same as a double-shear connection (Outside lug, middle lug, outside lug) then the pin is carrying the load in shear at just two locations.

If you design a hinge with many smaller lugs, don't you reduce the load on any one shear location on the pin?

(And if there are calculators out there for lug sizing, I've yet to find one. )

 

[alangbaker]

Think about it long and hard. Cuz I do not want to be driving full send following a car shedding parts.
Ever decide to pit a lap early and see the car leading you scatter itself all over turn one? Yeah, saw it from pit out road.

With that attitude, nothing would ever get tried.

Yes: I'm going to do all the due diligence I can do on this idea I've got. I'll use the tools I've got access to in Onshape, and I'll consult with people more knowledgeable than myself. But I'm going to move forward on this.

And I've seen race cars scatter parts on multiple occasions; race cars designed by engineers. A degree is no guarantee of perfection.

 

[CalG]

Just check into the myriad of proven hinge options offered for the aviation industry.

If it's possible, it has a proven design.

 

[claya]

You might find more hinge design data in a book, not Google. A lot of old school design resources have not been captured by the net. I am also a designer, and as inconvenient as it is, books are a much better resource for certain things. Have you found any hinge calculators on the major hinge sites? Guden etc.. What you want is certainly possible, as aircraft etc use massive pin/hinge joints. But as commented, hinge design is very basic shear load engineering.

 

[alangbaker]

You might find more hinge design data in a book, not Google. A lot of old school design resources have not been captured by the net. I am also a designer, and as inconvenient as it is, books are a much better resource for certain things. Have you found any hinge calculators on the major hinge sites? Guden etc.. What you want is certainly possible, as aircraft etc use massive pin/hinge joints. But as commented, hinge design is very basic shear load engineering.

I might need to resort to books, but the web comes to me, so it makes it a lot simpler if I can find it there.

But you're right about it being pretty straight forward shear load engineering (with the wrinkle that the axial loads are going to be very significant). My background is sufficient that I can handle (mostly handle) the kinematics of what I'm trying to achieve, but because this is for MY racing car (at least to begin), I'm very invested in making sure the structural side is sound.

Thanks for the thoughts. And I'm looking at the Guden website right now.

 

[alangbaker]

Just check into the myriad of proven hinge options offered for the aviation industry.

If it's possible, it has a proven design.

Where would I look?

 

[claya]

Where would I look?

Pretty sure the aviation stuff is designed internally from 60 year old designs. Ex: A lot of carrier aircraft use folding wings. Axial loading is just shear loading in a different plane.

 

[john.k]

Airplanes use piano type hinge for control surfaces ,and the hole is generally deep hole drilled ......which is needing specialized machines and tools

 

[alangbaker]

Airplanes use piano type hinge for control surfaces ,and the hole is generally deep hole drilled ......which is needing specialized machines and tools

Deep drilling could definitely be a factor. 1/4-5/16 (ish) pins through hinges 4-5 inches long, yeah. Worst case scenario, something like 20:1, but I might be able to open the pin diameter to as much as 1/2" and get something nearer 10:1

 

[Cole2534]

It seems to me that your design is going to come undone like a zipper in the event of a hard hit. To prevent that you'd need the leading lug to be able to bear the full load. Of course, this negates the benefit of the interior sections.

Also looks like a pain in the ass to lubricate, assemble/disassemble, and fabricate. And the little lugs are fragile- what happens when you ding one?

Possibly the most important part for a racecar- it looks to be full of friction and a great way to get erratic behavior.

I appreciate your desire to try something new, but this seems like a dead end.

 

[alangbaker]

It seems to me that your design is going to come undone like a zipper in the event of a hard hit. To prevent that you'd need the leading lug to be able to bear the full load. Of course, this negates the benefit of the interior sections.

Also looks like a pain in the ass to lubricate, assemble/disassemble, and fabricate. And the little lugs are fragile- what happens when you ding one?

Possibly the most important part for a racecar- it looks to be full of friction and a great way to get erratic behavior.

I appreciate your desire to try something new, but this seems like a dead end.

Those are pretty bold predictions from someone who doesn't even know what it's intended to do.

 

[john.k]

Race cars crash all the time .....part of the fun ......generally,if you get past the scrutineers ,its all good.

 

[Cole2534]

Those are pretty bold predictions from someone who doesn't even know what it's intended to do.

You did a spectacular job of not including any real details.