In a harmonic analysis, is the damping produced by MP,DMPR; TB,SDAMP; and DMPSTR constant vs frequency?
June 6, 2022 at 9:58 amFAQParticipant
No. For a single mode, the ratio to critical is greater at frequencies below resonance and smaller at frequencies above resonance. This is documented in the Structural Analysis Guide Section 1.2.4. You can find the complete equation in the ANSYS Help documentation, under “Mechanical APDL -> Theory Reference -> 14.3.3 equation 14-22 parameter g, mj, gEj”.
The damping contribution g is related to the damping matrix by
Omega is the excitation frequency. So (2*g/Omega) is a coefficient times the stiffness matrix like Beta damping.
Beta = 2*eta/omega
omega is the natural frequency while
2*g/Omega = 2*eta/omega:
eta (ratio to critical) = g(omega/Omega)
In a single degree of freedom test you will see the ratio to critical be higher at low excitation frequencies and lower at high excitation frequencies.
Introducing Ansys Electronics Desktop on Ansys Cloud
The Watch & Learn video article provides an overview of cloud computing from Electronics Desktop and details the product licenses and subscriptions to ANSYS Cloud Service that are...
How to Create a Reflector for a Center High-Mounted Stop Lamp (CHMSL)
This video article demonstrates how to create a reflector for a center high-mounted stop lamp. Optical Part design in Ansys SPEOS enables the design and validation of multiple...
Introducing the GEKO Turbulence Model in Ansys Fluent
The GEKO (GEneralized K-Omega) turbulence model offers a flexible, robust, general-purpose approach to RANS turbulence modeling. Introducing 2 videos: Part 1 provides background information on the model and a...
Postprocessing on Ansys EnSight
This video demonstrates exporting data from Fluent in EnSight Case Gold format, and it reviews the basic postprocessing capabilities of EnSight.
- How can I change the normalization method of the vibration modes from modal analysis?
- In the results of a modal analysis, how can I define that a frequency is an output parameter ?
- Why does the prestress from Static analysis does not add up to the stress in Random Vibration analysis?
- A Shock absorber is represented as spring element with damping constant. Modal analysis is performed using Reduced Damped (QRDAMP) solver. How to perform a Modal super position harmonic or transient analysis further ?
- What does the warning “Diagonal of the mass matrix is missing in file” indicate when using RSTMAC command?
- Why is damped frequency is lower than undamped frequency with viscous damping but larger with structural damping?
- How do I get a frequency response of acceleration in the radial direction of a cylinder?
- In a Modal Analysis of Mechanical, why aren’t the Participation Factors Summary under Solution Information displayed?
- What is mass moment of inertia in Point Mass used for?
- How to solve for harmonic response at a specific frequency in Workbench?