Energy dissipation of steel washers

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Discussion Overview

The discussion revolves around the use of steel washers on threaded bolts, specifically focusing on the optimum number of washers for energy dissipation towards the nut and the calculation of dissipation rates for each washer. The scope includes theoretical considerations and practical applications related to mechanical fastening and load distribution.

Discussion Character

  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • Some participants inquire about the optimum number of washers needed to effectively dissipate energy towards the nut.
  • One participant notes that standard washers serve to distribute pressure evenly and reduce friction during tightening and loosening, suggesting that they can enhance the tension applied to the bolt.
  • Another participant questions whether a single washer is sufficient or if multiple washers provide additional benefits beyond load distribution.
  • It is mentioned that depending on the application, washers may be required both at the bolt head and at the nut.
  • Some participants seek clarification on whether adding more washers increases the allowable tension on the nut or facilitates easier release of the nut.
  • One participant suggests that multiple washers of different sizes may be used to compensate for larger holes instead of using larger diameter components.

Areas of Agreement / Disagreement

Participants express varying opinions on the necessity and advantages of using multiple washers, indicating that there is no clear consensus on whether additional washers provide significant benefits in terms of tension application or ease of nut release.

Contextual Notes

The discussion does not resolve the mathematical or physical principles behind energy dissipation rates or the specific conditions under which multiple washers may be advantageous.

Evan.99
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Is there an optimum number of washers to be used on a threaded bolt in respect to dissipation of energy towards the nut? And how would one calculate the dissipation rate of each washer?
 
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Evan.99 said:
Is there an optimum number of washers to be used on a threaded bolt in respect to dissipation of energy towards the nut? And how would one calculate the dissipation rate of each washer?
Standard washers have two main purposes: To distribute the pressure of the nut evenly over the surface, so that the surface isn't damaged, and To ensure that the nut is pressed against a smooth surface, reducing the chance that it'll gradually loosen because it's in contact with an uneven surface. Another use for a washer is to reduce the friction when tightening and loosening. You can reach a greater tension on the bolt with a washer and when removing a bolt less torque is needed to break the bolt free from it tightened position. The so-called dissipation has to do with torque. The Washer should have a hardness that complies with the pressure expected based on the torque specification of the bolt.
 
Thanks. But does that mean that a single washer should always be enough or is there an advantage to having two or more (besides in cases where extra washers are used to distribute the load)?
 
Depending on the application you may need a washer at the bolt head and one at the nut for the stated reasons.
 
Ok, cheers. So just to clarify, adding more washers between the nut and the surface gives no advantage in terms of allowable tension applied to the nut or ease of releasing the nut again?
 
Evan.99 said:
Ok, cheers. So just to clarify, adding more washers between the nut and the surface gives no advantage in terms of allowable tension applied to the nut or ease of releasing the nut again?
If the hole is considerably larger than the shank people use multiple washers of different sizes to compensate instead of using a larger diameter bolt, washer and nut. Washers are used to spread the load of a bolt or screw over a larger area or to help prevent loosening under vibration.
 

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