Modal Analysis of centrifugal pump base frame using ASNYS Workbench
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- čas přidán 13. 07. 2018
- This video explains FEA Analysis of base frame of centrifugal pump & motor. This video briefs about introduction to modal analysis, equation, assumption and limitations of modal analysis. It also explains ansys simulation part like mesh creation FEA deck preparation, analysis setting for modal analysis. It explains analysis results like mode shapes, natural frequency, participation factors, how to avoid resonance, significance of participation factor, etc.
Update in video:
For modal Analysis, the linear equation of motion for free:
Un-damped Vibration: Mü +Ku=0
Damped Vibration: Mü+Ců+Ku=0
here, u is displacement not velocity (ů).
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Truly great content. in all of the data that has been dumped in CZcams this is something highly unusual actual useful content that nobody willing to teach.
You are the best sir!
What a great understanding of software! And explanation is awesome !
I will recommend your channel to my friends also.
Thank you for Appreciation !
This video precisely explains interpretation of modal analysis. Thank you and please keep posting such videos.
Thank you for appriciation
very great
Thank you
Thanks sir keep making such great videos !!
You are the BEST !!
Thank you for Appreciation !
Love you man..Keep making more videos.............
Thank you ! Please find more videos on our channel #graspengineering
Thank you so much Sir
Precise and to the point
You are most welcome
Nicely explained , keep making videos.
Thanks
Thank you for clear explanations.
Thank you for appreciation !
Thank you
Very beautifully explained
Thanks and welcome
Great video.
and the concept of mass participation factor is itself a study in this session , thanx for your time.
if possible please make the continuation part of the analysis such as random psd , frf . indeed it's really beneficial . thanx once again.
Hello, You will find more videos on #graspengineering channel mentioned in the description. You will find random vibration video too, link:. czcams.com/video/m7fAvQa59N4/video.html
I appreciate your work. Keep it up.
Thank You !
Good explanation sir....
Thanks and welcome
Hi! Could you please tell, why behaviour of your point masses was set as Deformable and not Rigid? Dont they stiffen enough the frame?
Hi.
There is one doubt. May be very simple for others.
We are assuming acceleration load is coming due to pump and motor.
If same load is coming from external shocks which excite the fixed support first like seismic load.
Plz suggest
Sir I want to know why tapping is given on the holes of a base frame for pump and motor installation?? Why not drilling the holes.
You're the best !
You can refer from Grabcadd library
Thanks for shearing :)
Thank you !
Awesome
Thank you !
thank you very much.
Welcome !
Hi! You have taken point masses at a remote location...Is it same as Lumped mass technique?
Yes
Hi,
What is the link for the reference for the geometry shown?
please mention here if possible.
Thanks in advance
Hello Please find below link from which you can download it.
www.graspengineering.com/centrifugal-pump-base-frame-cad-model/
can you do static analysis with apply nozzle load
Hi!
How will you decide that the number of modes extracted are sufficient.
For example: You considered point mass for compressor and motor. Both point masses do not have connection with each other. But there can be twisting of the connection between compressor and motor which can add mode that might be severe. And we don't see such modes on compressor bracket and motor bracket in the shown results.
Hello, at present we are interested to analyze base frame and hence we are more interested to see the frame mode shapes. So we assumed both motor and compressor as point mass.
Surely their is impact on modeling of motor & compressor, the stiffness of both motor and compressor will impact on mode shapes and natural frequency.
The better way to perform analysis is to model the complete the frame and simplify the compressor and motor geometry and attached as per actual scenario with correct mass.
Great tutorial sir.If you provide the link of 3d models, it will be more helpful for us.
Thank you ! We referred geometry file from grab-cad library.
did you get 3d model?? if yes please share
Very helpful. What type of support would be accurate under a Block type machine foundation for modal analysis ? Is it elastic support or is it right to assign compression only supports.
Elastic or compression only supports are representation of actual support conditions in FEA. You need check your model and accordingly choose the BC in FEA.
good
Thanks
You write wrong linear equation it just [k]{U} not a {ù} (dot). {Ù} dot means velocity and it's for damping and just displacement {u} for spring.
But very good presentation I appreciate that.
Thanks for highlighting, Please kindly Check the Description.
We machine similar base frames for pumps on our planomiller in ghaziabad. Some are even 4 meters long. And over 1 metre in height .
Sapphire Engineering Company Ghaziabad
You can share product video with us. We will try to highlight in our channel.
@@graspengineering9249 email ID
Please do the harmonic analysis for the same base frame and also apply damping to the base frame super presentation by the way
Please check description playlist, We have another video of harmonic analysis on other frame.
@@graspengineering9249 for the same base frame there is harmonic analysis using workbench if there is can please put a link in the discription
Is it possible to scale this up, lets say this pump was in a basement and you'd like to see its effect on the ground floor of the building. What do you think.
Yes, their will be effect. But usually their is some medium between pump and base floor to dampen the vibrations.
i do the same simulation for rail track, but i am not getting the ration of effective mass to total mass as 80-90%.
kindly suggest the case
Try to exctract few more mode shapes to gain more mass participation factor.
I have a base frame for dynamometer that runs at 18000 rpm. I modelled 3d model and completed 6 modes. Lowest fre. Required is 30% higher than operating speed as per dyno manufacturer. I need help to understand constraints and results. Thank you
You can either use constraints as per foundation or do free free analysis without constraints, in which first 6 modes are rigid body and later on you will get required modes. If you are expecting lower frequency 30hz more than operating then you can do design changes if you are not getting.
@@graspengineering9249Thank you for reply. You have point mass for motor and pump but both has stiffness. Is it ok to just add mass? If i do free free analysis 7th mode is 120hz. If i constrain i get 330 to 430 hz depend upon how i constrain. Sorry i m asking too many questions..
While entering mass, you can even enter mass moment of inertia in respective directions, it is further more accurate. You can consider motor mass too it will further affect minor frequency.
Instead of frequency you can check mode shapes in which directions it is moving, it should match with free free.
We need to think according to realistic condition Wether we need to idealized as mass or modeled complete structure.
R u interested in consulting? Its too late for this job but next time.
If you need any kind of help or consultation please drop mail to us, We will provide help ASAP.
thank you for the video. I did not understand the point you talked about at 20:42 , why and how we assess the mass ratio ?
The respective mass ratio is important to understand the participation of the respective mode. It represent the mass contributing to that mode and the sum of total ratio represents the total participation, suppose it is 90% in x it means 90 mass is taken into account into x direction. It suppose you have less mass participation then you can use missing mass or further increase modes to account more mass.you can access through output window in APDL & solution information or output file in workbench.
can you share pump drawing ?
Please make a video on modal plus harmonic analysis. We want to know how conduct a harmonic analysis for 1 octave sweep in ansys.
Okay
Hi, one question, motor and pump in the real instalation have a coupling between them, is necessary to use any contact between masses in the software?. In the video you use masses without relation/conection between them. Is correct to do this? Thank for your video
It is not possible to create contact between mass elements, In order to consider the connections as well as consider stiffness of both motor & pump, it is necessary to model both motor & pump in FEA Model. If you are looking to study only base frame then simplest way to idealized using masses and connect to their fixing point. The first approach is more realistic, but second one will also give similar results as first approach have negligible effect on results.
@@graspengineering9249 Thanks for your answer.
@@bssj7578 Welcome!
Thank you very much sir! i have a question: after conducting this modal analysis how can we choose a damper for the frame or the motor and pump mounts? Any help will be appreciated!
It is difficult to select the modal analysis results like mode shape and natural frequency. You might further need to perform the dynamic analysis (frequency response) for various damper and their compare the results withe each other and then select the most suitable.
@@graspengineering9249 Dear sir, i have a base frame sort of like yours on which an ic engine a gearbox and a generator are mounted. Now, from what i know any structure has infinite mode shapes and the natural frequency modes should not resonate with the excitation frequencies. This is to reduce vibration and as long as the two do not resonate the system is stable right? Also can you suggest any tutorial for dynamic analysis(frequency response). Thank you very much!
hello, thank you for your video. Would you tell me where I can find out your previous video?
Welcome, You will find more videos on #graspengineering channel mentioned in the description. Please check few link for base frame FEA like czcams.com/video/m7fAvQa59N4/video.html
Hi , can we get the CAD file of the base plate u have created ?
Please find the geometry on Grab-cad Library. Refer our video for more explanation: czcams.com/video/JdJ2FTcvFKc/video.html
We manufacture similar base frames for pumps
Whether the modal analysis is for centrifugal pump or for base frame?
It is for centrifugal pump base frame. Centrifugal pump and motor are idealized using mass elements.
What is the natural frequency of centrifugal pump alone?
You can include CP geometry and check the mode shapes coming on centrifugal pump or else model separate CP and perform the simulation.
Would you be able to send a link to the video that you model frame and added weld joints?
Please check this video link for 2D midsurface and weld work in ANSYS.
czcams.com/video/hzdRHs3VWHI/video.html
Would you please explain about three different type of Modal analysis a little bit more?
Please refer theoretical part. We will cover free free and fixed type modal analysis in our blogpost.
@@graspengineering9249 Thank you. I tried your blog post and it says that blog has been removed
Thank you for the video
Sir, how validate the results. How to determine the resonance frequency?
I need to know what frequency it is failing and how to determine it
Welcome! Resonance will occur when excitation frequency of equipment matches with natural frequency. So first check excitation frequency and correlate with natural frequency, if it matches it means chances of resonance.
@@graspengineering9249 excitation frequency means prestressed frequency table data to be compared with without prestressed modal analysis.. kindly guide me sir
In present case, Motor and centrifugal pump are idealized using mass element, both of them are rotating at some frequency or having some frequency, is called excitation frequency, Which we compare with natural frequency of base frame.
@@graspengineering9249
Sir, Thank you! im studing again from your videos.
Can you please guide me reference standard journals so that I will do case study on Modal+Random vibrations.
Also please suggest us which book is more suitable to learn FEA Dynamic analysis
i want this model this frame how can i get it please tell me. if i want to do same funtion in my software then i don't have any models for pratice
Hello. Most of cad model used are refereed from grab-cad library. You can refer link of the video below: czcams.com/video/JdJ2FTcvFKc/video.html. Also we started uploading cad model too, refer this link: grabcad.com/grasp.engineering-1/models
If you can suggest I am not able to get natural frequency from modal method??
Check your FEA Model connection, if few bodies are flying then you will zero frequency. Also if you have not fixed your model then first six mode are zero frequency mode, in such case you should extract more modes.
How to verify the results are correct or not...like what are the ways
You need to verify the reactions and try to match with applied eight of the geometry.
@@graspengineering9249 thanks sir, but I didn't understand with what i need to match the reactions?
What is the natural frequencies for the motor & pump excitation ?
Please check the modal analysis table shown in video. The first natural frequency is 13.1 Hz while excitation frequency is rotating speed of the motor.
@@graspengineering9249 Thank you sir, one more doubt- Normally the motor rpm is like 1000rpm so frequency if I calculate it's 16.67Hz, so do we need to consider electrical frequency of 50hz for comparison?
@@vilashification Yes. You should consider the rotating RPM for excitation frequency. No need to consider electrical frequency.
Hey, can you tell me which video to refer to create these frames please?! And what are the dimensions of the frame?! Please provide the link or name of that video
Hello. For modeling you can refer our Spaceclaim and design modeler playlist. You can also download this model from our blogpost: www.graspengineering.com/centrifugal-pump-base-frame-cad-model/
@@graspengineering9249 I downloaded the model, did all things, but from the downloaded model while solution I'm getting error of no volume defined. And I'm not able to define the volume, please help.
How to gotten this step file for practice
You can download from our blgopost. www.graspengineering.com/centrifugal-pump-base-frame-cad-model/
May I get modeling video of this frame?
You can refer from Grabcadd library.
Sir can I get the link to download cadd file
We referred from GrabCad and then did some changes in design modeler
@@graspengineering9249 OK sir thank you
I need to do modal analysis of Electric Vehicle chassis. then how should i take different weight distribution. because there are some point loads and some UDL? if possible give me your Email ID i will briefly explain about my queries. It is very good for me if i get some help
from you.
Hi, It is similar exercise as explained in this video. You can even perform prestress modal analysis. In static analysis you apply your loads and connect results to modal analysis.
Can share your drawing file to me for study purpose?😅😅
Please refer this link for cad file. www.graspengineering.com/centrifugal-pump-base-frame-cad-model/
@@graspengineering9249 Thank you very much😍
Sir for vibration analysis.... Abaqus is better or the ansys..... ... I want to work in field of vibration .... Can i have u r email id...
For vibration both are better...ANSYS is more user friendly....Abacus is better for nonlinear simulation...
@@graspengineering9249 .. One more thing dear how u have learned all these..... I mean what are books video u have used..... R u phd student....?
Great explanation!
Can you please provide your email id
Thank you !
@@graspengineering9249 Can you please explain PSD Response curve in detail. How can we relate it to Modal analysis results
@@KanwaljeetJaura The modal analysis is used to identify mode shapes and natural frequency while PSD is used to characterized random vibration of the equipment. We will cover more information on PSD in our blog. (www.graspengineering.com)
Thanks a lot. Please provide your email id , I need to clarify my doubt