Learning Forum

[dhruvdeshwal17]

I have modelled an eddy current damper, done its transient analysis. I got the various results , but keen interest is to calculated the damping force and damping coefficient associated with the dampers. Please suggest the procedure to calculated the same.nEddy Current dampers ( Basic Working) - In general ECD consist of a conducting plate and a magnet, which are placed adjacent to each other with a certain gap. A velocity (supposed) is given to the plate and the magnet remains stationary. So, as the plate move, the plate will see a change in a magnetic field by which eddy current will be generated in the plate and due to this current a magnetic field will be generated of opposite polarity as that of the magnet. Due to this generated magnetic field, the magnet experiences a force which is the damping force (In this case). n

[NKC]

Hi D_D ,

Which Ansys tool are you using?

If you are using Ansys Maxwell, you can calculate the force experienced by the magnet by assigning the force parameter to the magnet.

You can look at the Below help section to understand how to set up a transient problem.

If this did not solve your problem, explain How is your simulation setup and what results do you get with the help of some screenshots. This will help interpret the problem correctly.

Regards,

Navya

[dhruvdeshwal17]

Hi Array
Im using ANSYS 16.0 APDL

[wrbulat]

If the moving conductive region is continuous in the direction of motion (e.g., a rotating ring or disk), you can do this with a static analysis using the velocity effects feature. Mesh the conductor with SOLID236 and assign the velocity to the nodes of the conductor mesh using BF,ALL,VELO,vx,vy,vz,omegax,omegay,omegaz (specify angular velocity in units of radians/s). If you copy the text I pasted below into a text file and read it into MAPDL with the /INPUT command, you'll have an example:

fini

/cle

 

/pnu,mat,1

/num,1

 

/vie,1,1,2,3

 

/fil,236

/sys,del 236*.png

 

 

 

C*********************************************************

C*** PARAMETERS

C*********************************************************

pi=acos(-1)

 

k_nl=0 ! k_nl=0: LINEAR, k_nl=1: NONLINEAR

 

key_opt_2=0 ! KEYOPT(2) - 0: TRUE VOLT, 2: TIME INTEGRATED ELEC POT

key_opt_7=0 ! KEYOPT(7) - 0: ALL NODES, 1: CORNER NODES 

key_opt_8=0 ! KEYOPT(8) - 0: MAXWELL, 1: LORENTZ

 

r_PM=0.010 ! PM RADIUS

r1_cyl=0.012 ! CYLINDER INNER RADIUS

r2_cyl=0.015 ! CYLINDER OUTER RADIUS

r_dmn=0.025 ! RADIUS OF SURROUNNDING DOMAIN

r_gap=0.5*(r_PM+r1_cyl) ! RADIUS OF ARMINT INTERFACE IN AIRGAP

 

divr_cyl=7 ! # OF DIVISIONS IN RADIAL DIRECT IN CYLINDER

divz=5 ! # OF ELEMENT DIVISIONS IN AXIAL DIRECTION

 

l=0.050 ! CYLINDER LENGTH

l_end=0.025 ! LENGTH OF DOMAIN EXTENDING BEYOND END OF CYLINDER

 

Hc_PM=1e6 ! PM COERCIVITY

mur_PM=1.04 ! PM RELATIVE PERMEABILITY

 

rsv_cyl=3e-8 ! CYLINDER ELECTRIC RESISTIVITY

mur_cyl=1000 ! CYLINDER RELATIVE PERMEABILITY (USED IF k_nl=0)

 

RPM=50 !6000 ! ANGULAR VELOCITY, RPM (38 OK, 39 FAILS)

t_init=1e-9 ! TIME TO ESTABLISH INITIAL FIELD (NOT USED)

thta=45 ! ROTOR POSITION AT END OF TRANSIENT

t_final=t_init+(thta/360)/(RPM/60) ! TIME AT END OF TRANSIENT

nsteps=5 ! # OF TIME STEPS

 

*if,k_nl,eq,1,then

 /title,SOLID236 V15 VELOCITY EFFECTS, %RPM% RPM, CYL PERMEABILITY NONLINEAR

*else

 /title,SOLID236 V15 VELOCITY EFFECTS, %RPM% RPM, mur_cyl = %mur_cyl%

*endif

 

 

C*********************************************************

C*** GEOMETRY

C*********************************************************

/prep7

 

asel,none ! PM

pcir,r_PM,,0,90

aatt,2,2,200

 

asel,none ! CYLINDER

pcirc,r1_cyl,r2_cyl,0,90

aatt,3,3,200

 

alls

cm,keep_a,area

 

asel,none ! SURROUNDING AIR

pcirc,0,r_gap,0,90

pcirc,r_gap,r_dmn,0,90

cm,scrap_a,area

 

alls ! BOOLEAN SUBTRACTION

asba,scrap_a,keep_a,,dele,keep

cmse,u,keep_a

aatt,1,1,200

 

alls

aplo

 

 

 

C*********************************************************

C*** ATTRIBUTES, MESH

C*********************************************************

et,1,236 ! AIR

keyo,1,7,key_opt_7 ! FORCE OUTPUT

keyo,1,8,key_opt_8 ! FORCE CALCULATION

mp,murx,1,1

 

et,2,236 ! PM

keyo,2,7,key_opt_7 ! FORCE OUTPUT

keyo,2,8,key_opt_8 ! FORCE CALCULATION

mp,murx,2,mur_PM

mp,mgyy,2,Hc_PM

 

et,3,236,1 ! CYLINDER

keyo,3,2,key_opt_2 ! TRUE/TIME INTEGRATED VOLT

keyo,3,7,key_opt_7 ! FORCE OUTPUT

keyo,3,8,key_opt_8 ! FORCE CALCULATION

mp,murx,3,mur_cyl

mp,rsvx,3,rsv_cyl

 

mp,rsvx,3,rsv_cyl

 

*if,k_nl,eq,0,then

 mp,murx,3,mur_cyl

*else

 fifi1=0.94 ! hyperco 50 b-h 0.014in input, STATOR minimum

 tb,bh,3

 tbpt,defi,0,0

 tbpt,defi,2/0.01257,1.5*fifi1

 tbpt,defi,4/0.01257,1.8*fifi1

 tbpt,defi,5/0.01257,1.87*fifi1

 tbpt,defi,6/0.01257,1.93*fifi1

 tbpt,defi,8/0.01257,2.0*fifi1

 tbpt,defi,10/0.01257,2.05*fifi1

 tbpt,defi,20/0.01257,2.15*fifi1

 tbpt,defi,40/0.01257,2.195*fifi1

 tbpt,defi,50/0.01257,2.21*fifi1

 tbpt,defi,60/0.01257,2.225*fifi1

 tbpt,defi,80/0.01257,2.24*fifi1

 tbpt,defi,100/0.01257,2.25*fifi1

 tbpt,defi,150/0.01257,2.28*fifi1

 tbpt,defi,400/0.01257,2.4*fifi1

*endif

 

csys,1 ! # OF DIVISIONS THRU CYL THICKNESS

lsel,s,loc,x,r1_cyl+0.25*(r2_cyl-r1_cyl),r1_cyl+0.75*(r2_cyl-r1_cyl)

lesi,all,,,divr_cyl,,1

 

alls ! MESH AREAS

et,200,200,7

ames,all

 

csys,1 ! FULL 360 DEGREE GEOMETRY

agen,4,all,,,0,90,0

 

csys,1 ! MERGE NODES/KPS INSIDE ARMINT INTERFACE

ksel,s,loc,x,0,r_gap

lslk,s,1

asll,s,1

alls,belo,area

numm,node,1e-8,1e-8

numm,kp,1e-8,1e-8

 

csys,1 ! MERGE NODES/KPS OUTSIDE ARMINT INTERFACE

ksel,s,loc,x,r_gap,r_dmn

lslk,s,1

asll,s,1

alls,belo,area

numm,node,1e-8,1e-8

numm,kp,1e-8,1e-8

 

eplo

 

 

C********************************************

C*** EXTRUDE MESHED AREAS INTO MESHED VOLUMES

C********************************************

extopt,esize,divz,0

extopt,aclear,1

extopt,attr,1,1,1

 

csys

 

asel,s,mat,,1

type,1

vext,all,,,0,0,l/2

 

asel,s,mat,,2

type,2

vext,all,,,0,0,l/2

 

asel,s,mat,,3

type,3

vext,all,,,0,0,l/2

 

extopt,attr,0,0,0

 

vsel,s,mat,,1

alls,belo,volu

asel,r,loc,z,l/2

type,1, $mat,1, $real,1

vext,all,,,0,0,l_end

 

vsel,s,mat,,2

alls,belo,volu

asel,r,loc,z,l/2

type,1, $mat,1, $real,1

vext,all,,,0,0,l_end

 

vsel,s,mat,,3

alls,belo,volu

asel,r,loc,z,l/2

type,1, $mat,1, $real,1

vext,all,,,0,0,l_end

 

alls

vplo

 

csys,1 ! MERGE NODES/KPS INSIDE ARMINT INTERFACE

ksel,s,loc,x,0,r_gap

lslk,s,1

asll,s,1

vsla,s,1

alls,belo,volu

numm,node,1e-8,1e-8

numm,kp,1e-8,1e-8

cm,PM_v,volu

 

csys,1 ! MERGE NODES/KPS OUTSIDE ARMINT INTERFACE

ksel,s,loc,x,r_gap,r_dmn

lslk,s,1

asll,s,1

vsla,s,1

alls,belo,volu

numm,node,1e-8,1e-8

numm,kp,1e-8,1e-8

cm,cyl_v,volu

 

alls ! GO AHEAD AND MERGE ALL NODES - USE VELOCITY EFFECTS INSTEAD OF ARMINT

numm,node,1e-8,1e-8

numm,kp,1e-8,1e-8

eplo

 

 

 

C********************************************

C*** FLUX PARALLEL EXTERIOR

C********************************************

alls

asel,s,ext

csys,1

ksel,s,loc,x,r_gap

lslk,s,1

asll,u,1

!asel,u,loc,z

da,all,az

 

vsel,s,mat,,3

alls,belo,volu

asel,r,loc,z

da,all,volt

 

!alls,belo,volu

!asel,r,loc,z,l/2

!cp,1,volt,all

 

 

 

C********************************************

C*** APPLY VELOCTY TO ROTOR

C********************************************

vsel,s,mat,,3

alls,belo,volu

bf,all,velo,,,,,,RPM*2*pi/60 ! RADIANS/s

 

 

fini

 

 

C********************************************

C*** STATIC SOLVE

C********************************************

/solu

alls

pivc,off

 

*if,k_nl,gt,0,then

 

autots,on ! TURN ON AUTO TIME STEPPING

nsub,5,25,5 ! RANGE OF ALLOWABLE SUBSTEPS

outr,all,all ! SAVE ALL CALCULATED RESULTS

lnsr,on ! LINE SEARCH ALGORITHM CAN HELP WITH CONVERGENCE

kbc,0 ! RAMP APPLIED LOADS

 

*endif

 

save

solv

fini

 

 

 

C********************************************

C*** POST PROCESS

C********************************************

/post1

 

 

esel,s,mat,,3 ! CYLINDER MECHANICAL POWER (TORQUE TIMES OMEGA)

nsle

esln

emft

P_mech_cyl = 2*(2*pi*RPM/60)*_tzsum

 

 

esel,s,mat,,2 ! PM MECHANICAL POWER (TORQUE TIMES OMEGA)

nsle

esln

emft

P_mech_PM = 2*(2*pi*RPM/60)*_tzsum

 

 

vsel,s,mat,,3 ! DETERMINE HEAT PRODUCED IN CYLINDER

alls,belo,volu

set,last

etab,,jhea

etab,,volu

smult,ht,jhea,volu

ssum

*get,ht_total,ssum,,item,ht

ht_total=2*ht_total

 

 

/ann,dele

/tla,-0.25,0.90,Net Heat in Cylinder: %ht_total% W

/tla,-0.25,0.85,Cylinder Mechanical Power: %P_mech_cyl% W

/tla,-0.25,0.80,PM Mechanical Power: %P_mech_PM% W

 

 

plve,b,,,,vect,,on

/sho,png $plve,b,,,,vect,,on $/sho,close $/wait,2

 

plve,jt,,,,vect,,on

/sho,png $plve,jt,,,,vect,,on $/sho,close $/wait,2

 

rsys,1

plns,b,y

/sho,png $plns,b,y $/sho,close $/wait,2

 

plet,jhea,1

/sho,png $plet,jhea,1 $/sho,close $/wait,2

 

 

/eof

 

 

-- Bill