December 2, 2020 at 9:36 pmdbruneauSubscriber
Hi, I am trying to run an undamped Jeffcott rotor at speeds (1700-2000 rad/sec) above my critical speed (which is around 1070 rad/sec), but the support loads are unreasonably high (6000kN) in my transient analysis. Deformations are also unreasonably high. Below or slightly under critical speed they seem reasonable. I have tried modifying the majority of available parameters (ramping up the rotational velocity vs starting at high speed, decreasing the timestep, modifying internal damping, using line vs. solid models). The main reason for running the analysis in transient is to eventually estimate the bearing loads, including damping forces. Which analysis settings are important to include for supercritical rotors?December 10, 2020 at 9:22 pmDave LoomanAnsys EmployeeIn an undamped system, the steady state response at resonance is infinite, so the only thing limiting reaction forces is how quickly you pass through the critical speed. It would probably be best not to use large deflection as it will artificially increase the centrifugal force associated with lateral displacements. The rotational velocity is assumed to be centered on the undeformed axis when in actuality the rotor will spin about its center of mass. As a result lateral displacements produce huge centrifugal forces which aren't physical. Example 7.6 in the Rotordynamics Guide is a transient start-up analysis.nJanuary 10, 2021 at 5:42 pmsboSubscribernI am surprised to see that much reaction force in your analysis. Because there is no force in your analysis and only rotational velocity is defined. If you want see unbalance response in transient analysis, you should look transient analysis example in ansys manual. I cant remember example name. nViewing 2 reply threads
Ansys Innovation Space
- The topic ‘Supercritical Jeffcott Rotor Transient Analysis – Workbench’ is closed to new replies.
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.
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
- Saving & sharing of Working project files in .wbpz format
- Solver Pivot Warning in Beam Element Model
- Understanding Force Convergence Solution Output
- An Unknown error occurred during solution. Check the Solver Output…..
- What is the difference between bonded contact region and fixed joint
- The solver engine was unable to converge on a solution for the nonlinear problem as constrained.
- whether have the difference between using contact and target bodies
- Defining rigid body and contact
- Colors and Mesh Display
- A solver pivot warning or error has been detected
© 2023 Copyright ANSYS, Inc. All rights reserved.Ansys does not support the usage of unauthorized Ansys software. Please visit www.ansys.com to obtain an official distribution.