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How to Model Moving Mass in ANSYS

Ahmad Rafsanjani's picture

I want to model moving mass on a simply supported beam in ANSYS but I can not reach to analytical results, I tried defining CPs and some other methods. I want to find a linear solution and I prefer do not enter in Nonlinear analysis.

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Gopinath Venkatesan's picture

Dear Ahmad

You can simulate a moving load analysis in Ansys using transient dynamic analysis. But implementation of moving mass or moving oscillator is difficult in Ansys, and I also look forward to hear from experts here. I used Mathematica for the latter types. The modal properties of beam changes with the change in location of moving mass (if mass is considerable relative to beam mass), and you have to include updated frequency for each of the transient models that we use for regular moving load analysis.  Hope this helps.

Vgn

Graduate Student

University of Oklahoma

Ahmad Rafsanjani's picture

 Dear Gopinath Venkatesan

Thank you for your reply. I have seen some models presented by ( Andrea Mordini, Civil Engineer, Ph.D. http://www.andreamordini.com) in (ANSYS Forums: ANSYS Software Suite - moving mass) which suggests as below:

 Andrea says:

" I define the masses I need and I put some constraints on them. Then, when the masses enter the bridge, I release the constraint and I create a CP between the first mass and the first node on the bridge. In the subsequent step, I delete the CP and I create a new one with the next node on the bridge. The CP commands can be used in the SOLU processor."

But I could not follow the procedure, I hope experts here might help me according to Andrea's hint.

Best regards,

Ahmad Rafsanjani Abbasi

Iran University of Science & Technology

Gopinath Venkatesan's picture

Ahmad,

Since you are also working on moving load analysis, this may be of interest to you. There is a free software (only trial version) called BEDAS (Beam Exact Dynamic Analysis Software) is used to analyze beam structures under moving loads and masses. (forgot to include: Company name: Mecha Tools Technologies)

Regards,

Gopinath

Graduate Student 

University of Oklahoma 

Ahmad Rafsanjani's picture

ِDear Gopinath

Thank you for your suggestion. I provided the following information from this website:

 http://mechatools.com/BDS/bedas.htm

But there is no information about moving mass!!! 

 

BEDAS (Beams Exact Dynamic Analysis Software) is an easy to use bridge and  dynamic finite element program based on the exact dynamic stiffness method under the framework of exact finite éléments. BEDAS is a professional level bridge dynamic analysis  under moving loads program, with capabilities to handle most typical 2d mechanics, aeronautics and civil/structural analysis problems. It performs static, mode shapes and dynamic response analysis. It gives exact frequencies and mode shapes with only one element per span (member). Dynamic finite elements lead to higher precision of internal forces in any location of structure excited by fixed, moving and/or seismic loads. 

BEDAS is the leading 2D finite element program for the true dynamic bridge engineering under high speed moving load (pdf). The user focuses on the geometrical conditions and needs not spend time on matters regarding how to generate the finite element model.

Bedas Key Features: 

New CustomDesign feature (1,2)

Selection of base materials

   Mode shapes animation

Identification of the mode shape vibration for each beam in structure

 

  Fixed and/or moving loads analysis

  Fixed and/or moving distributed loads analysis

Seismic excitations

Loads may be applied in any location of the structure 

Load intensity may be gives by mathematical expression F(t)

The static response is given in addition to dynamic response

Visualize the solutions in displacements, velocities and accelerations (u, v and rotations), moments, shear-forces and axial-forces for the whole structure at time t between 0 and total time

Visualize the solution for the gage placed in any location 

Dynamic solution animation

Animated mode shapes, deflections and efforts diagrams

Bedas include components to get beam properties for general and standards sections.

Advanced Integrated CAD for sketching and drawing 2D frames

Pan, rotate and zoom using the mouse or keyboard

Library of complex commonly used 2D Frames can be quickly generated and assembled to form complex geometries

Results given in professional report

High Quality graphical results

Integrated units converter.

Dimensions view (quotations)

  Dynamic moving loads analysis. Use to analyze moving loads acting on

       Bridges or structures supporting mobile equipments with speeds.

BEDAS is the result of several international scientific papers and industrial experience of Dr. Kamel Henchi and the Research & development department.

Kind Regards, 

******************************************

 Ahmad Rafsanjani Abbasi

 Graduate Student

 School of Mechanical Engineering

 Acoustics Research Laboratory

 Iran University of Science and Technology

 Narmak 16844, Tehran, Iran

 rafsanjani@mecheng.iust.ac.ir

 *****************************************

Hi Abbasi, thanks for the information on BEDAS (Beams Exact Dynamic Analysis Software) , which is professional level bridge dynamic analysis  under moving loads program, with capabilities to handle most typical 2d mechanics, aeronautics and civil/structural analysis problems. Thanks once again. aplastic anemia treatment

Sir,

How toapply moving heat flux using GUI in ANSYS?

See the following reference:

Stancioiu D, Ouyang H, Mottershead JE. Vibration of a beam excited by a moving oscillator
considering separation and reattachment. Journal of Sound and Vibration 2008; 310(4-5):
1128-1140.

Ahmad Rafsanjani's picture

Dear Peter

I have seen this reference but I want to find how to model moving mass in ANSYS but the paper you mentioned does not contain this issue!

Thanks

Ahmad Rafsanjani

Acoustics Research Laboratory, IUST

rafsanjani@mecheng.iust.ac.ir

I send a solution to ur mail "rafsanjani@mecheng.iust.ac.ir"
hi i form shahrood univercity of technologoy and i master in mechanical engineering
I model a moving Load(Mass) in ansys that mooving over the simple suported baem this is very simple
U must aplead a load to first node and solve the problem and delete a load and solve again
and aplead a load to second node and solve again this loop result a good soloution to movung load.
the time inteval betwin the laod is (lenth of beam)/(velocity of load*number of node)

U can contact to me and IF U can talk and write and read Persia that very good
The moving load is the my bachelor proje

I realise this topic is more than likely closed, as there has been no activity for more than 6 months. But for future reference, there is a tutorial with accompanying ansys script, on how to model  moving load on a structure, which i have written at the following webpage www.varg.unsw.edu.au/movingload.htm . This can easily be modified to model a moving mass problem.

 

Cheers,

Gareth Forbes

www.varg.unsw.edu.au

Pandi.Pitchai's picture

Could anyone tell me how to write a uel subroutine in fortran for cohesive zone modeling based on XU-NEEDLEMAN traction separation law . 

 

With regards 

P.Pandi

IITM Madras

Ban.NguyenVan's picture

hi,

For moving load, you just simply asign to a load an amplitute with respect to the moving velocity and time.

you can have more refrence by search load amplitute in ABAQUS documentary search box

hope it help

Ban

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