Wheel stud failure

After seeing the new pic, I'm the opposite.
I'm seeing it starting at the ratcheting marks at the top, propagating to beach marks in the middle and final rapid fracture at the dark spot.
Fatigue failure...

 

Really effective technique. (Only issue is that it is dependent on bolt length, short bolt few flats, long bolt more flats, and the modulus of the clamped parts)

 

Turn-of-nut and fastener elongation are two different methods.
Turn-of-nut is +/- 15% accurate.
Fastener elongation is +/- 5% accurate

 

I thought I read a lot of posts here that started doing their own rotation after the dealer provided services and experienced broken studs. I think you may need to adjust to include dealer too (I mean we know they dont torque shit right). I can only imagine after so many on/off with the impact that it’s a matter of time I guess.

I know I check after them and find loose and over torque lugs and I use a torque wrench anytime the wheels come off

 

I would expect the dark spot to be where corrosion started. Usually, the "brighter" spots are the newest failures.

I'm not an expert in this, but the few failures I've had examined, that's the general rule of thumb that I get out of the results.

 

Sure because you are breaking 360 degrees into 6 equal segments. I've actually seen nuts with more markings than the number of flats.... I think 4 per flat. Even then, you could just break the nut down into 360 degrees or even finer for more precision. It's still a number of threads per inch (or pitch if going metric). You can still back out what you need.

But yes, elongation is the best measurement and in reality, all the methods used are to determine some type of elongation even if approximate. Bolt stretch is the whole point of a fastened joint. Have enough bolt stretch so that it doesn't loosen, but not too much that the bolt yields.

 

Strain gauges are +/- 1% accurate.

 

Breaker bar operator error .

 

OK, you guys made me go out and make sure all my lug nuts were there. They are so now I have peace of mind.

 

How do you put one on a bolt/stud? maybe one with a hollow center?

 

Yeah, you have to modify.
They seemed to be used more for testing and calibration, than actual application.

 

On those GE turbines I mentioned earlier. The big studs were actually hollowed out so you could use a heating element to "lengthen" the bolts. Then you could just turn the nuts the appropriate number of flats and once it cooled down you had the stretch. You might could stick a strain gauge in something like that, but you'd have to tighten without the heat.... hydraulic wrenches or hammer wrenches only then.

Anyways, I guess we're way off topic.

 

Interesting.

 

aint like a few have collapsed

fallen over the last year

 

Those were pins and sleeves. And the goofballs pulled all the pins ~300' up, u NEVER do that. Wind came through and did the rest

 

Update, I finally replaced my broken lug stud after 6 months.....

 

Same with cranes, kinda. U have a hydraulic head that threads onto the top of the stud, then stretches to ~200 bar then u run the nut down my "hand". Scary when u don't count the number of threads and she pops off the top.

 

Wooo!!

 

Was it overtightened?

 

Using a breaker bar on lug nuts is a no no,use a torque wrench.