Bolted connection joints - Pretension element

[elogesh]

Hi,

In one of the analysis requirement represented bolted connections between joint members using Prets179 with contact.

Beam 188 elements used for bolt connection. Bolt preload applied as the first load step and axial load applied as second load step.

Bolt diameter =12 mm; Bolt pre-load =50000N, Youngs modulus =2E5 Mpa Length of bolt (approx) =8 mm

Deformation of bolt = FL/AE = 0.017 mm

After performing this analysis, how to extract the bolt extension in first and second step..


Elogesh

 

[elogesh]

Dear All,

Along with this posted an attachment of APDL code to study the bolt joint stiffness ratio for simple two plate model.

But the joint stiffness ratio is affected by contact interface stiffness (FKN, Normal penalty stiffness).

The output from this execution writes an output file "Bolt_force_EX1.txt". In this you can observed that contact peneration is high(low FKN), but the bolt loads are logical and increasing under pulling external loads. But when contact penetratons are zero(High FKN), the bolt loads are decreasing and against the logic. So to decide the FKN value for rationale joint stiffness ratio, thought of seeing the bolt extension under preload and external load.But for applying the preload , the bolt divide into two halves. So not sure about the options to extract bolt beam displacement. Whetever I extracted as bolt displacement didn't match with calculated ones(FL/AE , F-force L-length, A-Area E =modulus) for the preload. Kindly let me know, how to extract bolt extension displacment and joint compression displacement under preload conditions.

Look forward for the directions from Ansys experts....

Advanced Thanks....
Elogesh


Link:

http://files.engineering.com/getfil..._v19_shell63Perfect_model_two_plate_force.txt

 

[elogesh]

Dear all,

Pl. find the APDL code pasted below.

The query is how to extract bolt deformation in structural analysis of joint members with bolted connection, which includes pre-tension elements and contact.







!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!To calculate bolt joint stiffness ratio!!!!!!!
!!!Two plate model!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

*do,a,0.01,1,0.01

PARSAV,SCALAR,'Parameters','txt',' '

Finish
/clear,start

/PREP7
PARRES,NEW,'Parameters','txt',' '


Sq_pl_dim=50 ! square plate dimension

Load_Sq_pl_dim=40 ! Square plate dimension- for load application

Bolt_dia=12 ! Bolt diameter

Bolt_rad=Bolt_dia/2 ! bolt radius

Washer_rad=1.5*Bolt_rad ! Washer diameter

Bolt_preload=50000 ! Bolt preload


Ext_force1=20000 ! External force


Plate1_thk=4 ! Thickness of joint members

Youngs_mod=2E5


Bolt_calc_stress_preload=Bolt_preload/(3.1415*Bolt_rad*Bolt_rad)
! Bolt stress calculation corresponding to preload = F/A !!!!!


Bolt_deformation=((3.1415*Bolt_rad*Bolt_rad)*(Youngs_mod))/(2*Plate1_thk)

!!!!!!!!!!!!!!!Bolt deformation =FL/AE !!!!!!!!!!

!*
ET,1,SHELL63
!*
KEYOPT,1,1,0
KEYOPT,1,3,0
KEYOPT,1,8,0
KEYOPT,1,9,0

mp,ex,1,2e5 ! Young's modulus of the material in MPa
mp,nuxy,1,0.3 ! Poissons ratio
mp,dens,1,7.85e-9 ! Density in Ton/mm3


btol,0.1e-3

R,1,4 ! Thickness of plate
RECTNG,-Sq_pl_dim,Sq_pl_dim,-Sq_pl_dim,Sq_pl_dim,
CYL4,0,0,Bolt_rad

ASBA, 1, 2

nummrg,all
numcmp,all

CYL4, , ,Bolt_rad, ,Washer_rad
aptn,all

CYL4, , ,Washer_rad, ,4*Bolt_rad
aptn,all

CSWPLA,11,0,1,1,

wprota,,90
asbw,all


wprota,,,90
asbw,all
alls
WPCSYS,-1,0
RECTNG,-Load_Sq_pl_dim,Load_Sq_pl_dim,-Load_Sq_pl_dim,Load_Sq_pl_dim,
aptn,all
WPCSYS,-1,0
CSWPLA,100,1,1,1,
CSYS,100,
asel,r,loc,x,0,Bolt_rad-1
aplot
adele,all
alls
aplot


WPCSYS,-1,0

CSWPLA,100,1,1,1,
CSYS,100,

asel,r,loc,x,0,4*Bolt_rad
aplot



esize,2

Type,1
mat,1
ESYS, 0
SECNUM, 1
MSHkey,1
amesh,all

alls

asel,u,loc,x,0,4*Bolt_rad
MSHkey,0
amesh,all

alls

agen,2,all,,,,,Plate1_thk,,0
EPLOT


ET,2,BEAM188
!*
SECTYPE, 2, BEAM, CSOLID, , 0
SECOFFSET, CENT
SECDATA,Bolt_rad,0,0,0,0,0,0,0,0,0,0,0

WPCSYS,-1,0
CSYS,0
WPAVE,0,0,0
CSYS,100
n,100000,0
n,200000,0,0,Plate1_thk/2
n,300000,0,0,Plate1_thk

TYPE, 2
MAT, 1
REAL,
ESYS, 0
SECNUM, 2
!*
e,100000,200000

*GET,High_elem_num1,ELEM,,NUM,MAX, , , ,

e,200000,300000

*GET,High_elem_num2,ELEM,,NUM,MAX, , , ,
alls

WPCSYS,-1,0

CSWPLA,100,1,1,1,
CSYS,100,

asel,r,loc,x,0,Washer_rad

ALLSEL,BELOW,AREA

nsel,r,loc,z,0
nsel,a,node,,100000

nplot

cerig,100000,all,all

allsel

asel,r,loc,x,0,Washer_rad

ALLSEL,BELOW,AREA

nsel,r,loc,z,Plate1_thk
nsel,a,node,,300000

nplot

cerig,300000,all,all

allsel

nplot

CSYS,0

nsel,r,loc,x,Sq_pl_dim
nsel,a,loc,x,-Sq_pl_dim

nsel,a,loc,y,Sq_pl_dim
nsel,a,loc,y,-Sq_pl_dim

nsel,r,loc,z,0

d,all,all,0

alls

WPCSYS,-1,0

CSWPLA,100,1,1,1,
CSYS,100,

nsel,r,loc,x,Washer_rad+1,4*Bolt_rad


Nplot

csys,0

nsel,r,loc,z,0

cm,nset1,node

alls



WPCSYS,-1,0

CSWPLA,100,1,1,1,
CSYS,100,

nsel,r,loc,x,Washer_rad+1,4*Bolt_rad


Nplot

csys,0

nsel,r,loc,z,Plate1_thk

cm,nset2,node

alls

nsel,r,loc,z,Plate1_thk
ESLN,R
EPLOT
ensym,,,,all
alls

ESEL,R,ENAME,,188
!*
PSMESH,111,pre, ,all, , 0,Z, ,200000


et,3,179

/COM, CONTACT PAIR CREATION - START
CM,_NODECM,NODE
CM,_ELEMCM,ELEM
CM,_KPCM,KP
CM,_LINECM,LINE
CM,_AREACM,AREA
CM,_VOLUCM,VOLU
/GSAV,cwz,gsav,,temp
MAT,1
R,3
REAL,3
ET,4,170
ET,5,174
KEYOPT,5,9,0
KEYOPT,5,10,2
R,3,
RMORE,
RMORE,,0
RMORE,0
KEYOPT,5,12,5
! Generate the target surface
NSEL,S,,,NSET1
CM,_TARGET,NODE
TYPE,4
ESLN,S,0
ESURF
CMSEL,S,_ELEMCM
! Generate the contact surface
NSEL,S,,,NSET2
CM,_CONTACT,NODE
TYPE,5
ESLN,S,0
ESURF
*SET,_REALID,3
ALLSEL
ESEL,ALL
ESEL,S,TYPE,,4
ESEL,A,TYPE,,5
ESEL,R,REAL,,3
/PSYMB,ESYS,1
/PNUM,TYPE,1
/NUM,1
EPLOT
ESEL,ALL
ESEL,S,TYPE,,4
ESEL,A,TYPE,,5
ESEL,R,REAL,,3
CMSEL,A,_NODECM
CMDEL,_NODECM
CMSEL,A,_ELEMCM
CMDEL,_ELEMCM
CMSEL,S,_KPCM
CMDEL,_KPCM
CMSEL,S,_LINECM
CMDEL,_LINECM
CMSEL,S,_AREACM
CMDEL,_AREACM
CMSEL,S,_VOLUCM
CMDEL,_VOLUCM
/GRES,cwz,gsav
CMDEL,_TARGET
CMDEL,_CONTACT
/COM, CONTACT PAIR CREATION - END
/COM, CONTACT PAIR PROPERTIES - START
KEYOPT,5,11,1
KEYOPT,5,12,0

RMODIF,3,3,a ! Effect of Normal penalty stiffness assessed
KEYOPT,5,9,1
KEYOPT,5,5,3

!! KEYOPT,5,2,1 ! Penalty method

KEYOPT,5,2,0 ! Augumented lagrange method

/COM, CONTACT PAIR PROPERTIES - END
/MREP,EPLOT
alls


WPCSYS,-1,0
CSWPLA,100,1,1,1,
CSYS,100,

/REPLOT
WPCSYS,-1,0
CSWPLA,100,1,1,1,
CSYS,100,
nsel,u,loc,x,Bolt_rad,Washer_rad+1
nsel,r,loc,x,Washer_rad+1,4*Bolt_rad
nplot
csys,0
!! nsel,r,loc,x,-Load_Sq_pl_dim,Load_Sq_pl_dim
nplot
!! nsel,r,loc,y,-Load_Sq_pl_dim,Load_Sq_pl_dim
nsel,r,loc,z,Plate1_thk

n,800000,0,0,Plate1_thk+0.1

Et,1000,21
R,1000,1e-3

Type,1000
Real,1000

E,800000



Cerigid,800000,all,all

nplot

cm,Ext_nodes,nodes

alls

finish

/solu



! New Pretension Section Load :: All Pret Sectns
SLOAD,ALL,9,LOCK,FORC,Bolt_preload, 1,2
alls

NSUBST,10,100,5
OUTRES,ERASE
OUTRES,ALL,ALL
TIME,1

lswrite,1
alls


/PSF,DEFA, ,2,0,1

/replo

f,800000,fz,Ext_force1

alls

NSUBST,10,100,5
OUTRES,ERASE
OUTRES,ALL,ALL
TIME,2

lswrite,2,

alls




alls
/solu
lssolve,1,2,1
finish

/post1

ESEL,R,ENAME,,188

SET,1,LAST,1,
ETABLE,Axi_for1,SMISC, 1,14

ETABLE,Dir_stress1,SMISC, 31,36


*GET,Force1_LS1,ELEM,High_elem_num1,ETAB,Axi_for1

*GET,Stress1_LS1,ELEM,High_elem_num1,ETAB,Dir_stress1


*GET,Force2_LS1,ELEM,High_elem_num2,ETAB,Axi_for1

*GET,Stress2_LS1,ELEM,High_elem_num2,ETAB,Dir_stress1

alls

ESEL,R,ENAME,,174

ETABLE,Cont_pene,NMISC, 9,10,11,12

*GET,Cont_pene_LS1,ELEM,6174,ETAB,Cont_pene

alls


SET,2,LAST,1,

ETABLE,Axi_for2,SMISC, 1,14

ETABLE,Dir_stress1,SMISC, 31,36


*GET,Force1_LS2,ELEM,High_elem_num1,ETAB,Axi_for2


*GET,Stress1_LS2,ELEM,High_elem_num1,ETAB,Dir_stress1


*GET,Force2_LS2,ELEM,High_elem_num2,ETAB,Axi_for2


*GET,Stress2_LS2,ELEM,High_elem_num2,ETAB,Dir_stress1


alls

ESEL,R,ENAME,,174

ETABLE,Cont_pene,NMISC, 9,10,11,12

*GET,Cont_pene_LS2,ELEM,6174,ETAB,Cont_pene

alls


Diff_Bolt21=Force1_LS2-Force1_LS1


alls

ESEL,S,ENAME,,174

ALLSEL,BELOW,ELEM
fsum,,both

SET,1,LAST,1,
fsum,,both
*GET,FSum_Z1,FSUM,,ITEM,FZ


SET,2,LAST,1,
fsum,,both
*GET,FSum_Z2,FSUM,,ITEM,FZ



Diff_joint21=FSum_Z1-FSum_Z2



joint_stifness_ratio1=Diff_Bolt21/Ext_force1

Diff1=Ext_force1-Diff_Bolt21-Diff_joint21



*do,i,1,2,1

SET,%i%,LAST,1,

/EFACET,1
PLNSOL, CONT,PRES, 0,1.0

*enddo

/EFACET,1
PLNSOL, CONT,PENE, 0,1.0

!!!Bolt_pre -Bolt preload !!!
!!!Joint_pre - Load at the joint interface corresponding to preload!!!!!
!!!External load - Applied external load!!!!!
!!!Bolt_Ext_load - Cumulative bolt load includes preload
!!Bolt_share_Ext - Share of external load taken by bolt
!!Joint_share_Ext - Share of external load taken by joint
!!JS_ratio - Joint stiffness ratio
!!Bolt_str_pre - Bolt stress preload
!!Bolt_str_Ext - Bolt stress external load
!!Cont_pene_LS2 - Contact penetration under external load


*CFOPEN,'Bolt_force_EX','txt',' ',APPEND
*VWRITE,'Bolt_Pre:','Joint_pre','Ext_load:','Bolt_Ext_load:','Bolt_share_Ext:','Joint_share_Ext:','JS_ratio','Bolt_str_pre','Bolt_str_Ext','Cont_pene_LS2'
(1X,A11,1X,A11,1X,A11,1X,A11,1X,A11,1X,A11,1X,A11,1X,A11,1X,A11,1X,A11)
*VWRITE,Force1_LS1,FSum_Z1,Ext_force1,Force1_LS2,Diff_Bolt21,Diff_joint21,joint_stifness_ratio1,Stress1_LS1,Stress1_LS2,Cont_pene_LS2
(F12.1,F12.1,F12.1,F12.1,F12.1,F12.1,F12.1,F12.1,F12.1,F12.1)
*CFCLOS

finish



*enddo

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!????How to extract bolt deformation under preload as well as external load!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!