Modal analysis

- November 13, 2019 at 1:51 pm
  
  Cri1994
  Subscriber
  
  Hi everyone,
  
  I'm doing modal analysis about a simple component. the component is a bar ( 40X16X500 mm).
  
  I have a question for you.
  
  The modal analysis launched with a bar in steel(2,512Kg) gives me these modes: 51,914 Hz, 128.95 Hz, 323Hz.
  
  The modal analysis launched with a bar in magnesium alloy ( m=0,576Kg) gives me these modes: 52.337 Hz, 130,08 Hz, 326,43 Hz.
  
  I think that it is non normal. What could be the problem? The materials settings?
  
  Thanks a lot for your time
  
  Cristiano
- November 14, 2019 at 2:00 am
  
  peteroznewman
  Subscriber
  
  Modal frequency is proportional to sqrt(K/M).
  
  K is proportional to Young's Modulus.
  
  Ratio of Steel to Magnesium Young's Modulus is 2e11/4.5e10 = 4.44
  
  Ratio of Steel to Magnesium Density is 7850/1800 = 4.361
  
  Expected Ratio of Modal Frequency Steel to Magnesium = sqrt(4.44/4.361) = 1.01
  
  This tells me that the modal frequencies being almost the same is expected.

Viewing 1 reply thread

You must be logged in to reply to this topic.

Ansys Innovation Space

Boost Ansys Fluent Simulations with AWS

Computational Fluid Dynamics (CFD) helps engineers design products in which the flow of fluid components is a significant challenge. These different use cases often require large complex models to solve on a traditional workstation. Click here to join this event to learn how to leverage Ansys Fluids on the cloud, thanks to Ansys Gateway powered by AWS.

Earth Rescue – An Ansys Online Series

The climate crisis is here. But so is the human ingenuity to fight it. Earth Rescue reveals what visionary companies are doing today to engineer radical new ideas in the fight against climate change. Click here to watch the first episode.

Ansys Blog

Subscribe to the Ansys Blog to get great new content about the power of simulation delivered right to your email on a weekly basis. With content from Ansys experts, partners and customers you will learn about product development advances, thought leadership and trends and tips to better use Ansys tools. Sign up here.

Trending discussions