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7075 aluminum thread pullout force question  
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Posted by: N74DV ^{®} 03/03/2004, 02:08:29 Author Profile Mail author Edit 
Basically what I'd like to know it if I have a 1/213 steel bolt threaded into a 7075 aluminum block about 1", what force would it take to fail the threads in the aluminum and pull out the bolt? Not looking for an exact number here just an estimate.
DJ V. Mesa, AZ 
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Thread Stress, PullOut, Engagment Calculation and Formula  
Re: 7075 aluminum thread pullout force question  N74DV  Post Reply  Top of thread  Forum 
Posted by: Administrator ^{®} 03/03/2004, 10:53:49 Author Profile Mail author Edit 
Just so everybody knows, after I publish a few hydraulic  flow formula and calculators, I will be publishing a series on this topic "Thread Stress, PullOut, Engagment Calculation and Formula". Here is my work in progress, the calculators are still being worked on:/thread_strength/thread_bolt_stress.htm
BTW, nice posts everybody! Modified by Administrator at Wed, Mar 03, 2004, 15:28:18 
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Re: 7075 aluminum thread pullout force question  
Re: 7075 aluminum thread pullout force question  N74DV  Post Reply  Top of thread  Forum 
Posted by: BJH ^{®} 03/03/2004, 10:30:17 Author Profile Mail author Edit 
Attached is some helpful info regarding threadstripout...hope it proves helpful... Thread Engagement To Prevent Stripping
Same Materials: Material the same for both internal and external threaded parts E = 2 (Ats) / [π * Dm { ½ + (n (Pd – Dm) / sq root of 3))}] where… E = length of engagement (inches)
Relative Strength: R = Ase * (Se) / Asi * (Si) where… R = relative strength factor (no units)
If R <= 1, then length of engagement is adequate. If R > 1, then the length of engagement (G) to prevent stripout is given as… G = E R Note:
Asi = π * n * E * Dm [ ( 1/2n) + {(Dm  Dp) / sq root 3}] where… Dp = maximum pitch diameter of internal thread

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Re: 7075 aluminum thread pullout force question  
Re: 7075 aluminum thread pullout force question  N74DV  Post Reply  Top of thread  Forum 
Posted by: Cragyon ^{®} 03/03/2004, 09:45:19 Author Profile Mail author Edit 
You can do the following (this is onlt an estimate), stress = load/area The area is the thread stress area, you can look in a chart or, use the following calculator /thread_stress_area_a.htm . (Use major diameter for an external thread anbd minor diameter for an internal thread your calculations) Determine the yield strength of you weakest part (the aluminum). Then, yield stress = [load maximum]/(thread stress area * number of threads of engagement) or, load maximum = [yield stress] * [thread stress area * number of threads of engagement)
Modified by Cragyon at Wed, Mar 03, 2004, 10:46:03 
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