enquiry about the output of MPC184 General Joint
Hi, there.
I am currently attempting to use APDL Transient and MPC184 element to measure the relative rotation angle between crank and connective bar in a crank slider mechanism. There are several output options to output the calculation result of interest in MPC184, however, no matter how I adjusted the orientation of the local coordinate system required for the joint, the output results were wrong although there was some change in result values. Below is the codes I wrote, could anyone please help check and fix it? Looking forward to your reply and suggestion.
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
/PREP7
K,1,0+10,0+10,0
K,2,0+10,10+10,0
N,3,0+10,10+10,0
N,4,sqrt(3)*10+10,0+10,0
N,5,sqrt(3)*10+10,0+10,0
N,16,sqrt(3)*10+10,10+10,0 !!trial point for muscle insertion
ET,1,MPC184
KEYOPT,1,1,0 !!rigid link
KEYOPT,1,2,1 !!
ET,3,MPC184
KEYOPT,3,1,6
KEYOPT,3,4,1 !!revolute joint
ET,4,MPC184
KEYOPT,4,1,10 !!translational joint
ET,5,MPC184
KEYOPT,5,1,16 !!General Joint
KEYOPT,5,4,0
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
ET,6,BEAM188
KEYOPT,6,3,0
SECNUM,120
SECTYPE,120,BEAM,CSOLID,,0
SECOFFSET,CENT
SECDATA,0.04
MP,EX,1,200e9
MP,PRXY,1,0.3
L,1,2
LESIZE,1,,,2,,1,,,1
LSEL,s,,,1
LATT,1,,6,,,,120
LMESH,1
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
CSYS
WPCSYS
WPAVE,+10,10
CSWPLA,100,0
CSYS
WPCSYS
WPAVE,0+10,10+10,0
!WPROTA,-180
WPROTA,,180
WPROTA,90
CSWPLA,101,0
WPCSYS
WPROTA,-30 !-30 !!30
CSWPLA,103,0
!WPCSYS
!WPAVE,0,20
!CSWPLA,104,0
CSYS
WPCSYS
WPAVE, sqrt(3)*10+10,0+10,0
WPROTA,150
!WPROTA,,180
!WPROTA,30
CSWPLA,102,0
WPCSYS
WPROTA,30 !-60
CSWPLA,104,0
CSYS
WPCSYS
SECNUM,100
TYPE,1
EN,113,3,4
!EN,150,16,3
!EN,151,16,4
CSYS
SECTYPE,101,JOINT,GENE,Gen_joint1
SECJOINT,LSYS,101,103 ! Defines the local coordinate systems for the joints.
SECJOINT,RDOF,1,2,3,4,5 ! Defines the relative DOFs to be constrained.
SECNUM,101
TYPE,5
EN,101,18,3
!!!!!!!!!!!!!!!!!!!!!!!!!
SECTYPE,102,JOINT,PRIS,Translational_joint
SECJOINT,LSYS,104,104
SECNUM,102
TYPE,4
EN,102,5,
!!!!!!!!!!!!!!!!!!!!!!!!!
SECTYPE,103,JOINT,REVO,REVO_joint1
SECJOINT,LSYS,100,100
SECNUM,103
TYPE,3
EN,103,17,
!!!!!!!!!!!!!!!!!!!!!!!!!
SECTYPE,106,JOINT,GENE,Gen_joint2
SECJOINT,LSYS,102,104 ! Defines the local coordinate systems for the joints.
SECJOINT,RDOF,1,2,3,4,5 ! Defines the relative DOFs to be constrained.
SECNUM,106
TYPE,5
EN,106,4,5
NDELE,16
!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!load
ALLSEL
CSYS
WPCSYS
ALLSEL
aa=1.57*4
D,19,ROTZ,aa
!D,16,UZ,0
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!solution
ALLSEL
CSYS
/SOLU
ANTYPE,TRANS
TRNOPT,full
!solcontrol,on,on
NLGEOM,ON !!!!!Includes large-deflection effects in a static or full transient analysis
autots,AUTO !!!!!!!Specifies whether to use automatic time stepping or load stepping
TIME,1
DELTIM,0.01,0.001,0.01
TIMINT,ON
KBC,0
OUTRES,all,all
SOLVE
/PSYMB,CS,1
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! Post Processor
ALLSEL
/POST1
!CSYS,101
!RSYS,101
SET,1,25 !!!14
ETABLE,SMIS36,SMISC,36 !36 !66 !!relative rotation
ESOL,2,101,18,SMISC,36
ESEL,s,,,101
ESEL,a,,,106
PRETAB,SMIS36
ETABLE,ERAS
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
ALLSEL
ETABLE,Joint_RR,SMISC,66 !42 !36 !66 !!relative rotation
ESEL,s,,,103
PRETAB, Joint_RR
ETABLE,ERAS
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
ALLSEL
ETABLE,Joint_RU,SMISC,61 !!relative displacement
ESEL,s,,,102
PRETAB,Joint_RU
Many thanks,
Linjie Wang
PhD student
Department of Engineering and Design
University of Sussex
Brighton, BN1 9RH
United Kingdom
Just a quick guess but do you need to rotate nodes into local coord systems?
From the manual:
"NROTAT, NODE1, NODE2, NINC
Rotates nodal coordinate systems into the active system."
From PADT:
"14: NROTATE
One thing to be very aware of is that each node in a model has a rotation associated with it. By default, the UX, UY, and UZ degrees of freedom are oriented with the global Cartesian coordinate system. In ANSYS Mechanical, when you specify a load or a boundary condition as normal or tangent to a surface, the program actually rotates all of those nodes so a degree of freedom is normal to that surface.
If you need to do that yourself because you want to apply a load or boundary condition in a certain direction besides the global Cartesian, use NROTATE. You basically select the nodes you want to rotate, specify the active coordinate system with CSYS, then issue NROTATE,ALL to rotate them.
Be careful though. You don't want to screw with any rotations that ANSYS Mechanical specified."
Thank you,
Scott
Husqvarna Group | 8825 Statesville Road | Charlotte NC 28269
(980) 345-1344 | scott.richardson@husqvarnagroup.com
-----Original Message-----
From: Linjie Wang [mailto:lw302@sussex.ac.uk]
Sent: Thursday, October 19, 2017 10:07 AM
To: xansys-temp@xansystest.info
Subject: [Xansys] enquiry about the output of MPC184 General Joint
Hi, there.
I am currently attempting to use APDL Transient and MPC184 element to measure the relative rotation angle between crank and connective bar in a crank slider mechanism. There are several output options to output the calculation result of interest in MPC184, however, no matter how I adjusted the orientation of the local coordinate system required for the joint, the output results were wrong although there was some change in result values. Below is the codes I wrote, could anyone please help check and fix it? Looking forward to your reply and suggestion.
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
/PREP7
K,1,0+10,0+10,0
K,2,0+10,10+10,0
N,3,0+10,10+10,0
N,4,sqrt(3)*10+10,0+10,0
N,5,sqrt(3)*10+10,0+10,0
N,16,sqrt(3)*10+10,10+10,0 !!trial point for muscle insertion
ET,1,MPC184
KEYOPT,1,1,0 !!rigid link
KEYOPT,1,2,1 !!
ET,3,MPC184
KEYOPT,3,1,6
KEYOPT,3,4,1 !!revolute joint
ET,4,MPC184
KEYOPT,4,1,10 !!translational joint
ET,5,MPC184
KEYOPT,5,1,16 !!General Joint
KEYOPT,5,4,0
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
ET,6,BEAM188
KEYOPT,6,3,0
SECNUM,120
SECTYPE,120,BEAM,CSOLID,,0
SECOFFSET,CENT
SECDATA,0.04
MP,EX,1,200e9
MP,PRXY,1,0.3
L,1,2
LESIZE,1,,,2,,1,,,1
LSEL,s,,,1
LATT,1,,6,,,,120
LMESH,1
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
CSYS
WPCSYS
WPAVE,+10,10
CSWPLA,100,0
CSYS
WPCSYS
WPAVE,0+10,10+10,0
!WPROTA,-180
WPROTA,,180
WPROTA,90
CSWPLA,101,0
WPCSYS
WPROTA,-30 !-30 !!30
CSWPLA,103,0
!WPCSYS
!WPAVE,0,20
!CSWPLA,104,0
CSYS
WPCSYS
WPAVE, sqrt(3)*10+10,0+10,0
WPROTA,150
!WPROTA,,180
!WPROTA,30
CSWPLA,102,0
WPCSYS
WPROTA,30 !-60
CSWPLA,104,0
CSYS
WPCSYS
SECNUM,100
TYPE,1
EN,113,3,4
!EN,150,16,3
!EN,151,16,4
CSYS
SECTYPE,101,JOINT,GENE,Gen_joint1
SECJOINT,LSYS,101,103 ! Defines the local coordinate systems for the joints.
SECJOINT,RDOF,1,2,3,4,5 ! Defines the relative DOFs to be constrained.
SECNUM,101
TYPE,5
EN,101,18,3
!!!!!!!!!!!!!!!!!!!!!!!!!
SECTYPE,102,JOINT,PRIS,Translational_joint
SECJOINT,LSYS,104,104
SECNUM,102
TYPE,4
EN,102,5,
!!!!!!!!!!!!!!!!!!!!!!!!!
SECTYPE,103,JOINT,REVO,REVO_joint1
SECJOINT,LSYS,100,100
SECNUM,103
TYPE,3
EN,103,17,
!!!!!!!!!!!!!!!!!!!!!!!!!
SECTYPE,106,JOINT,GENE,Gen_joint2
SECJOINT,LSYS,102,104 ! Defines the local coordinate systems for the joints.
SECJOINT,RDOF,1,2,3,4,5 ! Defines the relative DOFs to be constrained.
SECNUM,106
TYPE,5
EN,106,4,5
NDELE,16
!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!load
ALLSEL
CSYS
WPCSYS
ALLSEL
aa=1.57*4
D,19,ROTZ,aa
!D,16,UZ,0
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!solution
ALLSEL
CSYS
/SOLU
ANTYPE,TRANS
TRNOPT,full
!solcontrol,on,on
NLGEOM,ON !!!!!Includes large-deflection effects in a static or full transient analysis
autots,AUTO !!!!!!!Specifies whether to use automatic time stepping or load stepping
TIME,1
DELTIM,0.01,0.001,0.01
TIMINT,ON
KBC,0
OUTRES,all,all
SOLVE
/PSYMB,CS,1
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! Post Processor ALLSEL
/POST1
!CSYS,101
!RSYS,101
SET,1,25 !!!14
ETABLE,SMIS36,SMISC,36 !36 !66 !!relative rotation
ESOL,2,101,18,SMISC,36
ESEL,s,,,101
ESEL,a,,,106
PRETAB,SMIS36
ETABLE,ERAS
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
ALLSEL
ETABLE,Joint_RR,SMISC,66 !42 !36 !66 !!relative rotation
ESEL,s,,,103
PRETAB, Joint_RR
ETABLE,ERAS
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
ALLSEL
ETABLE,Joint_RU,SMISC,61 !!relative displacement
ESEL,s,,,102
PRETAB,Joint_RU
Many thanks,
Linjie Wang
PhD student
Department of Engineering and Design
University of Sussex
Brighton, BN1 9RH
United Kingdom
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Husqvarna Group
Husqvarna Consumer Outdoor Products N.A.
Husqvarna Canada Corp.
Husqvarna Construction Products North America Inc.
9335 Harris Corners Parkway, Suite 500
Charlotte, NC 28269 USA
www.husqvarna.comhttp://www.husqvarna.com/
850 Matheson Blvd. West, Unit 1
Mississauga, ON L5V 0B4 Canada
www.husqvarna.cahttp://www.husqvarna.ca/
17400 W 119th Street
Olathe, KS 66061 USA
www.husqvarnacp.comhttp://www.husqvarnacp.com/
2077 Bond Street,
North Bay,
ON P1B 4V7 Canada
www.husqvarnacp.cahttp://www.husqvarnacp.ca/
Husqvarna respects your privacy and does not share or sell email addresses. If you no longer wish to receive emails from Husqvarna, please send a mail to unsubscribe@husqvarnagroup.commailto:unsubscribe@husqvarnagroup.com?subject=unsubscribe
The information in this email may be confidential and/or legally privileged. It has been sent for the sole use of the intended recipient(s). If you are not an intended recipient, you are strictly prohibited from reading, disclosing, distributing, copying or using this email or any of its contents, in any way whatsoever. If you have received this email in error, please contact the sender by reply email and destroy all copies of the original message. Please also be advised that emails are not a secure form for communication, and may contain errors.
Hi, Scott.
Thanks a lot for your quick reply.
I just tried NROTAT. The value is not correct either, even though each result of rotation angle was affected.
May I ask you one more question? Do you know how to measure the relative motions (translations and rotations) of two moving bodies after solving the transient analysis? I am quite confused how to extract those results since the local CS defined in APDL would not move with analysis results in each substep.
Many thanks,
Linjie
-----Original Message-----
From: Scott Richardson [mailto:scott.richardson@husqvarnagroup.com]
Sent: 19 October 2017 15:30
To: XANSYS Mailing List Temporary Home xansys-temp@xansystest.info
Subject: Re: [Xansys] enquiry about the output of MPC184 General Joint
Just a quick guess but do you need to rotate nodes into local coord systems?
From the manual:
"NROTAT, NODE1, NODE2, NINC
Rotates nodal coordinate systems into the active system."
From PADT:
"14: NROTATE
One thing to be very aware of is that each node in a model has a rotation associated with it. By default, the UX, UY, and UZ degrees of freedom are oriented with the global Cartesian coordinate system. In ANSYS Mechanical, when you specify a load or a boundary condition as normal or tangent to a surface, the program actually rotates all of those nodes so a degree of freedom is normal to that surface.
If you need to do that yourself because you want to apply a load or boundary condition in a certain direction besides the global Cartesian, use NROTATE. You basically select the nodes you want to rotate, specify the active coordinate system with CSYS, then issue NROTATE,ALL to rotate them.
Be careful though. You don't want to screw with any rotations that ANSYS Mechanical specified."
Thank you,
Scott
Husqvarna Group | 8825 Statesville Road | Charlotte NC 28269
(980) 345-1344 | scott.richardson@husqvarnagroup.com
-----Original Message-----
From: Linjie Wang [mailto:lw302@sussex.ac.uk]
Sent: Thursday, October 19, 2017 10:07 AM
To: xansys-temp@xansystest.info
Subject: [Xansys] enquiry about the output of MPC184 General Joint
Hi, there.
I am currently attempting to use APDL Transient and MPC184 element to measure the relative rotation angle between crank and connective bar in a crank slider mechanism. There are several output options to output the calculation result of interest in MPC184, however, no matter how I adjusted the orientation of the local coordinate system required for the joint, the output results were wrong although there was some change in result values. Below is the codes I wrote, could anyone please help check and fix it? Looking forward to your reply and suggestion.
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
/PREP7
K,1,0+10,0+10,0
K,2,0+10,10+10,0
N,3,0+10,10+10,0
N,4,sqrt(3)*10+10,0+10,0
N,5,sqrt(3)*10+10,0+10,0
N,16,sqrt(3)*10+10,10+10,0 !!trial point for muscle insertion
ET,1,MPC184
KEYOPT,1,1,0 !!rigid link
KEYOPT,1,2,1 !!
ET,3,MPC184
KEYOPT,3,1,6
KEYOPT,3,4,1 !!revolute joint
ET,4,MPC184
KEYOPT,4,1,10 !!translational joint
ET,5,MPC184
KEYOPT,5,1,16 !!General Joint
KEYOPT,5,4,0
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
ET,6,BEAM188
KEYOPT,6,3,0
SECNUM,120
SECTYPE,120,BEAM,CSOLID,,0
SECOFFSET,CENT
SECDATA,0.04
MP,EX,1,200e9
MP,PRXY,1,0.3
L,1,2
LESIZE,1,,,2,,1,,,1
LSEL,s,,,1
LATT,1,,6,,,,120
LMESH,1
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
CSYS
WPCSYS
WPAVE,+10,10
CSWPLA,100,0
CSYS
WPCSYS
WPAVE,0+10,10+10,0
!WPROTA,-180
WPROTA,,180
WPROTA,90
CSWPLA,101,0
WPCSYS
WPROTA,-30 !-30 !!30
CSWPLA,103,0
!WPCSYS
!WPAVE,0,20
!CSWPLA,104,0
CSYS
WPCSYS
WPAVE, sqrt(3)*10+10,0+10,0
WPROTA,150
!WPROTA,,180
!WPROTA,30
CSWPLA,102,0
WPCSYS
WPROTA,30 !-60
CSWPLA,104,0
CSYS
WPCSYS
SECNUM,100
TYPE,1
EN,113,3,4
!EN,150,16,3
!EN,151,16,4
CSYS
SECTYPE,101,JOINT,GENE,Gen_joint1
SECJOINT,LSYS,101,103 ! Defines the local coordinate systems for the joints.
SECJOINT,RDOF,1,2,3,4,5 ! Defines the relative DOFs to be constrained.
SECNUM,101
TYPE,5
EN,101,18,3
!!!!!!!!!!!!!!!!!!!!!!!!!
SECTYPE,102,JOINT,PRIS,Translational_joint
SECJOINT,LSYS,104,104
SECNUM,102
TYPE,4
EN,102,5,
!!!!!!!!!!!!!!!!!!!!!!!!!
SECTYPE,103,JOINT,REVO,REVO_joint1
SECJOINT,LSYS,100,100
SECNUM,103
TYPE,3
EN,103,17,
!!!!!!!!!!!!!!!!!!!!!!!!!
SECTYPE,106,JOINT,GENE,Gen_joint2
SECJOINT,LSYS,102,104 ! Defines the local coordinate systems for the joints.
SECJOINT,RDOF,1,2,3,4,5 ! Defines the relative DOFs to be constrained.
SECNUM,106
TYPE,5
EN,106,4,5
NDELE,16
!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!load
ALLSEL
CSYS
WPCSYS
ALLSEL
aa=1.57*4
D,19,ROTZ,aa
!D,16,UZ,0
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!solution
ALLSEL
CSYS
/SOLU
ANTYPE,TRANS
TRNOPT,full
!solcontrol,on,on
NLGEOM,ON !!!!!Includes large-deflection effects in a static or full transient analysis
autots,AUTO !!!!!!!Specifies whether to use automatic time stepping or load stepping
TIME,1
DELTIM,0.01,0.001,0.01
TIMINT,ON
KBC,0
OUTRES,all,all
SOLVE
/PSYMB,CS,1
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! Post Processor ALLSEL
/POST1
!CSYS,101
!RSYS,101
SET,1,25 !!!14
ETABLE,SMIS36,SMISC,36 !36 !66 !!relative rotation
ESOL,2,101,18,SMISC,36
ESEL,s,,,101
ESEL,a,,,106
PRETAB,SMIS36
ETABLE,ERAS
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
ALLSEL
ETABLE,Joint_RR,SMISC,66 !42 !36 !66 !!relative rotation
ESEL,s,,,103
PRETAB, Joint_RR
ETABLE,ERAS
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
ALLSEL
ETABLE,Joint_RU,SMISC,61 !!relative displacement
ESEL,s,,,102
PRETAB,Joint_RU
Many thanks,
Linjie Wang
PhD student
Department of Engineering and Design
University of Sussex
Brighton, BN1 9RH
United Kingdom
Xansys-temp mailing list
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Please send administrative requests such as deletion from XANSYS to xansys-mod@tynecomp.co.uk and not to the list Husqvarna Group
Husqvarna Consumer Outdoor Products N.A.
Husqvarna Canada Corp.
Husqvarna Construction Products North America Inc.
9335 Harris Corners Parkway, Suite 500
Charlotte, NC 28269 USA
www.husqvarna.comhttp://www.husqvarna.com/
850 Matheson Blvd. West, Unit 1
Mississauga, ON L5V 0B4 Canada
www.husqvarna.cahttp://www.husqvarna.ca/
17400 W 119th Street
Olathe, KS 66061 USA
www.husqvarnacp.comhttp://www.husqvarnacp.com/
2077 Bond Street,
North Bay,
ON P1B 4V7 Canada
www.husqvarnacp.cahttp://www.husqvarnacp.ca/
Husqvarna respects your privacy and does not share or sell email addresses. If you no longer wish to receive emails from Husqvarna, please send a mail to unsubscribe@husqvarnagroup.commailto:unsubscribe@husqvarnagroup.com?subject=unsubscribe
The information in this email may be confidential and/or legally privileged. It has been sent for the sole use of the intended recipient(s). If you are not an intended recipient, you are strictly prohibited from reading, disclosing, distributing, copying or using this email or any of its contents, in any way whatsoever. If you have received this email in error, please contact the sender by reply email and destroy all copies of the original message. Please also be advised that emails are not a secure form for communication, and may contain errors.
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Linjie,
For rotation you could get the locations of 2 points (nodes) per body, calculate the direction vectors at each time of interest, and calculate the rotation manually. As long as the deformation isn't too severe this may give you what you want.
Aaron Caba, Ph.D. | Sr. Member Technical Staff | Nuvotronics, Inc.
7586 Old Peppers Ferry Loop | Radford, VA 24141
www.nuvotronics.com
-----Original Message-----
From: Linjie Wang [mailto:lw302@sussex.ac.uk]
Sent: Thursday, October 19, 2017 11:52 AM
To: XANSYS Mailing List Temporary Home xansys-temp@xansystest.info
Subject: Re: [Xansys] enquiry about the output of MPC184 General Joint
Hi, Scott.
Thanks a lot for your quick reply.
I just tried NROTAT. The value is not correct either, even though each result of rotation angle was affected.
May I ask you one more question? Do you know how to measure the relative motions (translations and rotations) of two moving bodies after solving the transient analysis? I am quite confused how to extract those results since the local CS defined in APDL would not move with analysis results in each substep.
Many thanks,
Linjie
-----Original Message-----
From: Scott Richardson [mailto:scott.richardson@husqvarnagroup.com]
Sent: 19 October 2017 15:30
To: XANSYS Mailing List Temporary Home xansys-temp@xansystest.info
Subject: Re: [Xansys] enquiry about the output of MPC184 General Joint
Just a quick guess but do you need to rotate nodes into local coord systems?
From the manual:
"NROTAT, NODE1, NODE2, NINC
Rotates nodal coordinate systems into the active system."
From PADT:
"14: NROTATE
One thing to be very aware of is that each node in a model has a rotation associated with it. By default, the UX, UY, and UZ degrees of freedom are oriented with the global Cartesian coordinate system. In ANSYS Mechanical, when you specify a load or a boundary condition as normal or tangent to a surface, the program actually rotates all of those nodes so a degree of freedom is normal to that surface.
If you need to do that yourself because you want to apply a load or boundary condition in a certain direction besides the global Cartesian, use NROTATE. You basically select the nodes you want to rotate, specify the active coordinate system with CSYS, then issue NROTATE,ALL to rotate them.
Be careful though. You don't want to screw with any rotations that ANSYS Mechanical specified."
Thank you,
Scott
Husqvarna Group | 8825 Statesville Road | Charlotte NC 28269
(980) 345-1344 | scott.richardson@husqvarnagroup.com
-----Original Message-----
From: Linjie Wang [mailto:lw302@sussex.ac.uk]
Sent: Thursday, October 19, 2017 10:07 AM
To: xansys-temp@xansystest.info
Subject: [Xansys] enquiry about the output of MPC184 General Joint
Hi, there.
I am currently attempting to use APDL Transient and MPC184 element to measure the relative rotation angle between crank and connective bar in a crank slider mechanism. There are several output options to output the calculation result of interest in MPC184, however, no matter how I adjusted the orientation of the local coordinate system required for the joint, the output results were wrong although there was some change in result values. Below is the codes I wrote, could anyone please help check and fix it? Looking forward to your reply and suggestion.
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
/PREP7
K,1,0+10,0+10,0
K,2,0+10,10+10,0
N,3,0+10,10+10,0
N,4,sqrt(3)*10+10,0+10,0
N,5,sqrt(3)*10+10,0+10,0
N,16,sqrt(3)*10+10,10+10,0 !!trial point for muscle insertion
ET,1,MPC184
KEYOPT,1,1,0 !!rigid link
KEYOPT,1,2,1 !!
ET,3,MPC184
KEYOPT,3,1,6
KEYOPT,3,4,1 !!revolute joint
ET,4,MPC184
KEYOPT,4,1,10 !!translational joint
ET,5,MPC184
KEYOPT,5,1,16 !!General Joint
KEYOPT,5,4,0
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
ET,6,BEAM188
KEYOPT,6,3,0
SECNUM,120
SECTYPE,120,BEAM,CSOLID,,0
SECOFFSET,CENT
SECDATA,0.04
MP,EX,1,200e9
MP,PRXY,1,0.3
L,1,2
LESIZE,1,,,2,,1,,,1
LSEL,s,,,1
LATT,1,,6,,,,120
LMESH,1
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
CSYS
WPCSYS
WPAVE,+10,10
CSWPLA,100,0
CSYS
WPCSYS
WPAVE,0+10,10+10,0
!WPROTA,-180
WPROTA,,180
WPROTA,90
CSWPLA,101,0
WPCSYS
WPROTA,-30 !-30 !!30
CSWPLA,103,0
!WPCSYS
!WPAVE,0,20
!CSWPLA,104,0
CSYS
WPCSYS
WPAVE, sqrt(3)*10+10,0+10,0
WPROTA,150
!WPROTA,,180
!WPROTA,30
CSWPLA,102,0
WPCSYS
WPROTA,30 !-60
CSWPLA,104,0
CSYS
WPCSYS
SECNUM,100
TYPE,1
EN,113,3,4
!EN,150,16,3
!EN,151,16,4
CSYS
SECTYPE,101,JOINT,GENE,Gen_joint1
SECJOINT,LSYS,101,103 ! Defines the local coordinate systems for the joints.
SECJOINT,RDOF,1,2,3,4,5 ! Defines the relative DOFs to be constrained.
SECNUM,101
TYPE,5
EN,101,18,3
!!!!!!!!!!!!!!!!!!!!!!!!!
SECTYPE,102,JOINT,PRIS,Translational_joint
SECJOINT,LSYS,104,104
SECNUM,102
TYPE,4
EN,102,5,
!!!!!!!!!!!!!!!!!!!!!!!!!
SECTYPE,103,JOINT,REVO,REVO_joint1
SECJOINT,LSYS,100,100
SECNUM,103
TYPE,3
EN,103,17,
!!!!!!!!!!!!!!!!!!!!!!!!!
SECTYPE,106,JOINT,GENE,Gen_joint2
SECJOINT,LSYS,102,104 ! Defines the local coordinate systems for the joints.
SECJOINT,RDOF,1,2,3,4,5 ! Defines the relative DOFs to be constrained.
SECNUM,106
TYPE,5
EN,106,4,5
NDELE,16
!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!load
ALLSEL
CSYS
WPCSYS
ALLSEL
aa=1.57*4
D,19,ROTZ,aa
!D,16,UZ,0
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!solution
ALLSEL
CSYS
/SOLU
ANTYPE,TRANS
TRNOPT,full
!solcontrol,on,on
NLGEOM,ON !!!!!Includes large-deflection effects in a static or full transient analysis
autots,AUTO !!!!!!!Specifies whether to use automatic time stepping or load stepping
TIME,1
DELTIM,0.01,0.001,0.01
TIMINT,ON
KBC,0
OUTRES,all,all
SOLVE
/PSYMB,CS,1
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! Post Processor ALLSEL
/POST1
!CSYS,101
!RSYS,101
SET,1,25 !!!14
ETABLE,SMIS36,SMISC,36 !36 !66 !!relative rotation
ESOL,2,101,18,SMISC,36
ESEL,s,,,101
ESEL,a,,,106
PRETAB,SMIS36
ETABLE,ERAS
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
ALLSEL
ETABLE,Joint_RR,SMISC,66 !42 !36 !66 !!relative rotation
ESEL,s,,,103
PRETAB, Joint_RR
ETABLE,ERAS
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
ALLSEL
ETABLE,Joint_RU,SMISC,61 !!relative displacement
ESEL,s,,,102
PRETAB,Joint_RU
Many thanks,
Linjie Wang
PhD student
Department of Engineering and Design
University of Sussex
Brighton, BN1 9RH
United Kingdom
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On Oct 19, 2017, at 9:07 AM, Linjie Wang wrote:
I am currently attempting to use APDL Transient and MPC184 element
to measure the relative rotation angle between crank and connective
bar in a crank slider mechanism.
A few questions.
Are you trying to find the rigid body rotations between the crank and
the bar or the elastic deformation?
Are you looking for relative displacements of the nodes or absolute
rotations of the slider and crank?
How do you know what's wrong if you don't know what's right? How do
you know what's right?
The straightforward way to figure rigid body movement is simple
geometry. Pick 3 points and calculate the angles of the triangle
defined by those points with the model in the initial position and
then calculate the angles of the triangle with the model in the
deformed position using the nodal displacements added to the original
locations. Make yourself a diagram showing the two displaced
triangles to help with the trigonometry. Then do the math. There will
be rotations due to rigid body translation of the triangle and due to
relative movement of each leg in a mechanism like you've described. A
diagram will help sort these out if you need to.
If I were to guess, the rigid body rotations will likely be many
times greater than the elastic displacements--mechanisms are normally
designed this way to provide for precise movements, So you won't have
to try to sort out elastic and rigid body movement.
Christopher Wright P.E. |"They couldn't hit an elephant at
chrisw@skypoint.com | this distance" (last words of Gen.
.......................................| John Sedgwick, Spotsylvania
1864)
http://www.skypoint.com/members/chrisw/
Thanks, Chris.
Basically, I am using this mechanism to validate the functions of MPC184 General Joint/Revolute Joint. Because my project model is a knee joint which possesses three rotation DOFs and three translational DOFs. This Knee joint consists of two parts, tibia and femur. Each of them has its own local coordinate system and these two LCS will rotate around other two Local coordinate systems (hip joint center and ankle joint center) during one gait motion. So if I want to calculate the relative motions between femur and tibia, I need to apply matrix transformation several times in each time substep, which would be too complicated with another calculation algorithm. However, since I noticed MPC184 has the outputs of relative rotations, I attempted to build a simple model to test their validity. Unfortunately, I haven't figured it out so far.
Best regards,
Linjie
Linjie Wang
PhD student
Department of Engineering and Design
University of Sussex
Brighton, BN1 9RH
United Kingdom
On 19 Oct 2017, at 8:38 PM, Christopher Wright chrisw@skypoint.com wrote:
On Oct 19, 2017, at 9:07 AM, Linjie Wang wrote:
I am currently attempting to use APDL Transient and MPC184 element to measure the relative rotation angle between crank and connective bar in a crank slider mechanism.
A few questions.
Are you trying to find the rigid body rotations between the crank and the bar or the elastic deformation?
Are you looking for relative displacements of the nodes or absolute rotations of the slider and crank?
How do you know what's wrong if you don't know what's right? How do you know what's right?
The straightforward way to figure rigid body movement is simple geometry. Pick 3 points and calculate the angles of the triangle defined by those points with the model in the initial position and then calculate the angles of the triangle with the model in the deformed position using the nodal displacements added to the original locations. Make yourself a diagram showing the two displaced triangles to help with the trigonometry. Then do the math. There will be rotations due to rigid body translation of the triangle and due to relative movement of each leg in a mechanism like you've described. A diagram will help sort these out if you need to.
If I were to guess, the rigid body rotations will likely be many times greater than the elastic displacements--mechanisms are normally designed this way to provide for precise movements, So you won't have to try to sort out elastic and rigid body movement.
Christopher Wright P.E. |"They couldn't hit an elephant at
chrisw@skypoint.com | this distance" (last words of Gen.
.......................................| John Sedgwick, Spotsylvania 1864)
http://www.skypoint.com/members/chrisw/
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On Oct 19, 2017, at 4:30 PM, Linjie Wang lw302@sussex.ac.uk wrote:
Each of them has its own local coordinate system and these two LCS will rotate around other two Local coordinate systems (hip joint center and ankle joint center) during one gait motion.
The local systems in ANSYS don't move. They're reference systems whose orientation and translation are fixed, once they're defined. Same with element systems.
So if I want to calculate the relative motions between femur and tibia, I need to apply matrix transformation several times in each time substep, which would be too complicated with another calculation algorithm. However, since I noticed MPC184 has the outputs of relative rotations, I attempted to build a simple model to test their validity.
I don't understand much of this, but I can't imagine that an APDL function to do the arithmetic would be so complicated.
Christopher Wright P.E. |"They couldn't hit an elephant at
chrisw@skypoint.com | this distance" (last words of Gen.
.......................................| John Sedgwick, Spotsylvania 1864)
http://www.skypoint.com/members/chrisw/
Well, I hope LCS move with the model I mean, but ANSYS can't.
Thanks,
Linjie
-----Original Message-----
From: chrisw@skypoint.com [mailto:chrisw@skypoint.com]
Sent: 20 October 2017 05:54
To: XANSYS Mailing List Temporary Home xansys-temp@xansystest.info
Subject: Re: [Xansys] enquiry about the output of MPC184 General Joint
On Oct 19, 2017, at 4:30 PM, Linjie Wang lw302@sussex.ac.uk wrote:
Each of them has its own local coordinate system and these two LCS will rotate around other two Local coordinate systems (hip joint center and ankle joint center) during one gait motion.
The local systems in ANSYS don't move. They're reference systems whose orientation and translation are fixed, once they're defined. Same with element systems.
So if I want to calculate the relative motions between femur and tibia, I need to apply matrix transformation several times in each time substep, which would be too complicated with another calculation algorithm. However, since I noticed MPC184 has the outputs of relative rotations, I attempted to build a simple model to test their validity.
I don't understand much of this, but I can't imagine that an APDL function to do the arithmetic would be so complicated.
Christopher Wright P.E. |"They couldn't hit an elephant at
chrisw@skypoint.com | this distance" (last words of Gen.
.......................................| John Sedgwick, Spotsylvania 1864) http://www.skypoint.com/members/chrisw/
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On Oct 20, 2017, at 3:10 AM, Linjie Wang wrote:
Well, I hope LCS move with the model I mean, but ANSYS can't.
Hope is for buying lottery tickets, not engineering analysis. With
ANSYS, you need proof.
Christopher Wright P.E. |"They couldn't hit an elephant at
chrisw@skypoint.com | this distance" (last words of Gen.
.......................................| John Sedgwick, Spotsylvania
1864)
http://www.skypoint.com/members/chrisw/