Maximizing Thread Strength: Stress Analysis on M10 Bolt with 100 kg Load

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In summary, the study focuses on the stress analysis of an M10 bolt subjected to a 100 kg load to maximize thread strength. It examines the distribution of stress along the bolt and the impact of various factors, including material properties and thread geometry, on the bolt's performance under load. The findings aim to enhance the design and reliability of bolted connections in engineering applications.
  • #1
Aerstz
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Homework Statement
Calculate the stress in a screw thread resulting from a known force
Relevant Equations
Stress = Force / (0.25 * pi * (nominal thread diameter - 0.93194 * pitch)^2
A load of 100 kg acting in the axial direction is applied to a nut coupled with a standard M10 bolt. The nominal thread diameter is 10 mm; pitch is 1.5 mm. Thus, the stress acting on a single thread in the bolt is:

1000 N / (0.25 * pi * (10 mm - 0.93194 * 1.5 mm)^2) ≈ 17.21 MPa

17 MPa seems rather low. If a nut covers 5-threads, the total stress is therefore just 3 MPa (17/5), translating to a maximum load acting on the steel nut (assuming proof strength of ~200 MPa) of approximately 10-tons.

10-tons seems a lot of weight before a loaded M10 nut will strip a bolt of its threads, which is why I'm posting this to request clarification/verification, please?
 
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  • #3
Lnewqban said:
Please, see:
https://www.engineeringtoolbox.com/metric-nut-proof-load-d_2029.html

https://www.engineeringtoolbox.com/metric-bolts-minimum-ultimate-tensile-proof-loads-d_2026.html

https://www.engineeringtoolbox.com/steel-bolts-metric-grades-d_1428.html
Thanks. Judging by the information in these links, my calculation is about five-times out. What confuses me is that the formula I used I took from a report I produced years ago, and I cannot recall where it came from, and I am unable to find it anywhere online (I even asked an AI bot). In my report, the predicted stress was verified by FEA, so why my result here is so disagreeable with the tabulated values you linked me to I have no idea.
 
  • #4
Aerstz said:
Thanks. Judging by the information in these links, my calculation is about five-times out. What confuses me is that the formula I used I took from a report I produced years ago, and I cannot recall where it came from, and I am unable to find it anywhere online (I even asked an AI bot). In my report, the predicted stress was verified by FEA, so why my result here is so disagreeable with the tabulated values you linked me to I have no idea.
You may have your answer by now but you are confusing tensile thread stress in the bolt and nut shear stress. The tensile stress is force/area independent of thread number.

The nut shear stress is force/ nut shear area which is pi x D x nut depth, usually three thread engagement
 
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FAQ: Maximizing Thread Strength: Stress Analysis on M10 Bolt with 100 kg Load

What is the significance of analyzing thread strength in bolts?

Analyzing thread strength in bolts is crucial because the threads are the primary contact points that bear the load. Understanding their strength helps ensure that the bolt can withstand the applied forces without failing, which is essential for the safety and reliability of mechanical assemblies.

How is stress calculated for an M10 bolt under a 100 kg load?

Stress is calculated using the formula: Stress = Force / Area. For an M10 bolt, the force can be derived from the weight (100 kg), converted to Newtons (approximately 980 N), and the tensile stress area of the bolt threads is used to determine the effective area over which the load is distributed. The resulting stress can then be compared to the material's yield strength.

What factors affect the thread strength of a bolt?

Several factors affect the thread strength of a bolt, including the material properties (such as tensile strength and ductility), the thread design (such as pitch and depth), the surface finish, and any preloading or torque applied during installation. Environmental conditions, such as corrosion or temperature, can also influence thread performance.

What are the common failure modes for bolts under load?

The common failure modes for bolts under load include tensile failure (where the bolt stretches and ultimately breaks), shear failure (where the bolt fails due to lateral forces), and thread stripping (where the threads deform or shear off). Additionally, fatigue failure can occur if the bolt is subjected to cyclic loading over time.

How can the thread strength of an M10 bolt be improved?

The thread strength of an M10 bolt can be improved through several methods, including using higher-grade materials, applying surface treatments (like hardening or coating), optimizing the thread design, and ensuring proper installation techniques (such as adequate torque and preloading). Regular maintenance and inspection can also help prevent thread failure.

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