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

  • Context: Engineering 
  • Thread starter Thread starter Aerstz
  • Start date Start date
  • Tags Tags
    Load Stress
Click For Summary

Discussion Overview

The discussion revolves around the stress analysis of an M10 bolt subjected to a 100 kg axial load, focusing on the calculations of thread stress and the implications for thread stripping and nut strength. The scope includes theoretical calculations, verification against standard values, and clarification of stress types in threaded connections.

Discussion Character

  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant calculates the stress on a single thread of the M10 bolt to be approximately 17.21 MPa, suggesting that this is low and questioning the implications for thread stripping under a 100 kg load.
  • Another participant provides links to external resources that may contain relevant information about proof loads and tensile strengths of bolts and nuts.
  • A later reply indicates that the initial calculation may be significantly off, suggesting a misunderstanding between tensile stress in the bolt and shear stress in the nut, emphasizing that tensile stress is independent of the number of threads engaged.
  • The same participant notes that the shear stress in the nut should be calculated based on the nut's shear area, which is influenced by the number of threads engaged.

Areas of Agreement / Disagreement

Participants express differing views on the accuracy of the initial stress calculation and the interpretation of stress types in the context of threaded connections. There is no consensus on the correct approach or the validity of the initial calculations.

Contextual Notes

The discussion highlights potential limitations in the initial calculations, including the dependence on definitions of stress types and the assumptions made in the calculations. There is also an indication of unresolved discrepancies between the participant's calculations and standard values.

Aerstz
Messages
35
Reaction score
0
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?
 
Physics news on Phys.org
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.
 
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
 
Last edited by a moderator:

Similar threads

Tensile Stress Analysis of Bolted Connection
  • · Replies 1 ·
Replies
1
Views
2K
Reusability of nuts and tapped holes + Choosing the right material
  • · Replies 3 ·
Replies
3
Views
2K
What is the Stress in a Bolt and Spacer System?
  • · Replies 48 ·
2
Replies
48
Views
11K
Corrugated tube (bellow) under axial load
  • · Replies 2 ·
Replies
2
Views
2K
Calculating total stress in bolts that holds an actuator?
  • · Replies 5 ·
Replies
5
Views
11K
Strength calculations of threaded spindle.
  • · Replies 1 ·
Replies
1
Views
5K
Graduate Will Ice Shattering Affect the Impact Load on a Power Station Roof?
  • · Replies 3 ·
Replies
3
Views
7K