Plate mode shape subjected to damage

In summary, the conversation discusses questions related to vibration and the possibility of changing the mode shapes of a metal plate by chipping off a small part. The speaker mentions observing mode shapes at 100 Hz and 300 Hz and wonders if both frequencies will be affected or just the top antinode part. They also mention trying to find an ANSYS user for help and the suggestion of using LISA-8 for analysis.
  • #1
bulgogii
5
0
Hello Peeps~ I have couple of questions related to vibration and I would really appreciate some help from you experts out there.

Anyways, say I have a metal plate with mode shapes observed at 100 Hz and 300 Hz as shown in the below figures. If I were to chip(cut) off a small part of the plate(top corner), will the mode shape for both frequencies totally change? or will just the top antinode part("mountain shape") will change? which frequency range (100 Hz or 300 Hz) will be more severly changed in general?
upload_2015-9-30_16-24-37.png
upload_2015-9-30_16-25-3.png


Figure 1. at 100 Hz Figure 2. at 300 Hz

This question would of been easy if I had ANSYS but... I wouldn't understand the reasons for the result anyway :(
 
Last edited:
  • #3
Ah well~ I'll try and find ANSYS user and ask for help~
 
  • #4
There was no way of answering this properly without doing full analysis on a plate with actual dimensions and constraints .

OP - try using LISA-8 . Excellent and costs nothing .
 

1. What is meant by "plate mode shape"?

"Plate mode shape" refers to the natural vibration pattern or shape of a plate when subjected to a specific type of force or load. This shape is dependent on factors such as the material properties and geometry of the plate, and is often studied in structural engineering and mechanical engineering applications.

2. How does damage affect the mode shape of a plate?

Damage to a plate, such as a crack or a dent, can alter its mode shape by changing the stiffness and mass distribution of the plate. This can lead to changes in the natural frequency and amplitude of the vibration, which can have significant effects on the performance and structural integrity of the plate.

3. What methods are used to analyze plate mode shapes subjected to damage?

Various analytical and numerical methods can be used to analyze plate mode shapes subjected to damage. These include modal analysis, finite element analysis, and experimental techniques such as laser vibrometry. Each method has its own advantages and limitations, and the choice of method often depends on the specific application and available resources.

4. How does the location of damage on a plate affect its mode shape?

The location of damage on a plate can greatly influence its mode shape. Damage near the edges or corners of the plate can have a greater impact on the mode shape compared to damage in the center. Additionally, the type of damage (e.g. crack, dent, etc.) can also affect the mode shape differently.

5. Can damage in a plate be detected by analyzing its mode shape?

Yes, changes in the mode shape of a plate can be indicative of damage. By comparing the mode shapes of a healthy plate and a damaged plate, it is possible to identify regions of damage and estimate the severity of the damage. This can be a useful tool for detecting and monitoring damage in structures without the need for physical inspection.

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