Mechanical vibration and shock control

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Discussion Overview

The discussion revolves around controlling vibrations and shocks in electronic-mechanical components, focusing on concepts such as natural frequency, its estimation, and the implications of excitation on material failure. The scope includes theoretical understanding, practical applications, and potential learning resources.

Discussion Character

  • Exploratory
  • Technical explanation
  • Homework-related

Main Points Raised

  • One participant seeks help on controlling vibrations and shocks in electronic-mechanical components.
  • Another participant suggests formal education and mentorship for deeper understanding.
  • A query is raised about the definition and estimation of natural frequency.
  • Natural frequency is described as an inherent vibration mode of structures, which can be calculated or measured through techniques like modal analysis.
  • A request for resources on calculating natural frequency using modal analysis is made.
  • A link to a resource on modal analysis is provided by a participant.
  • A question is posed regarding how materials fail under excitation and the factors influencing this failure.
  • It is suggested that material failure is related to fatigue and strength, particularly when excitation frequency matches the natural frequency.
  • Concerns are raised about the implications of reaching or being close to the natural frequency, emphasizing the importance of understanding these dynamics.

Areas of Agreement / Disagreement

Participants express various viewpoints on the relationship between excitation frequency and natural frequency, with some suggesting that matching these frequencies can lead to failure, while others note that design and damping can mitigate risks. The discussion remains unresolved regarding the specifics of material failure mechanisms.

Contextual Notes

Participants reference concepts such as fatigue, strength of materials, and S-N diagrams, indicating a need for a foundational understanding of these topics to fully engage in the discussion.

sri.karmarkar
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Please could anyone help me on the topic "Controlling the vibration and shocks received by elctronic-mechanical components"?
 
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Sure. Take a year or two of college classes and then learn more under a mentor in the field.

Can you be a bit more specific with your request?
 
Thank you fred for your reply and suggestions.

I will start learning on the topic and will be enquiring where i get strucked. I will try to mention the topic more specific.

The first query from me
"What is natural frequency and how it can be obtained or estimated?".
 
The natural frequency is a vibration mode that is inherent to all structures. It is the frequency that the structure will vibrate at if the body is given a single impulse. In other words, it is the frequency that the body will vibrate at on its own, without an external forcing of any kind other than an initial "push."

Natural frequencies are calculated as well as measured through various techniques such as modal analysis.
 
Thanks fred.
Where can i get an example of calculating the natural frequency by modal analysis?
Please help me. Any links so that i can get a clear picture on this?
 
try this
http://cp.literature.agilent.com/litweb/pdf/5954-7957E.pdf
 
Last edited by a moderator:
Thank you so much rb.. let me go through this.
 
How the materials fails when it is subjected to excitation?
what are the influencing factors?
Material fails is it because of lone factor "excitation frequncy reaches more than the natural frequency?".
 
The influencing factors are the basics of fatigue and strength of materials. If you excite a structure's natural frequency, it can take no time at all for that structure to reach its fatigue life. It gets amplified by the fact that the alternating stresses can be quite a bit higher than one would expect at any other operating point. Take a look at a basic S-N diagram to get an idea about this.

[quote="sri.karmarkar]Material fails is it because of lone factor "excitation frequncy reaches more than the natural frequency?". [/quote]
The point to be worried about is when the excitation frequency matches the natural frequency. If you are above or below it, you shouldn't need to worry about it. Even if you do reach the natural frequency, sometimes it's not a big deal due to the design or the system's ability to dmpen vibrations. Still if you are close to the natural frequency, you need to know what the result will be. You can't ignore it. This is why we do things like shaker and modal testing.
 

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