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How to get capture Debonding or CFRP rupture in Load-Displacement Curve? — Ansys Learning Forum

How to get capture Debonding or CFRP rupture in Load-Displacement Curve?

Mshrest2Mshrest2 Member Posts: 5


I am modeling RCC beam with NSM CFRP strengthening. Concrete is CPT215, Steel Rebar is Reinf264, and NSM epoxy and CFRP both are both Solid185. I am trying to simulate sudden dropdown in Load-displacement curve as shown in picture of experimental result. However my analysis goes on and on when I add load steps as shown in the picture. The sudden drop down corresponds either to the debonding (more specific concrete cover separation near epoxy-concrete interface) or rupture of CFRP.


I have attached the script material properties I have applied for CF

RP, epoxy and Contact elements. Con you suggest me how to get the drop down in the curve? 


! Orthotropic Material Properties of CFRP NSM


MPTEMP,,,,,,,,  

MPTEMP,1,0  

MPDATA,EX,5,,200000

MPDATA,EY,5,,14050

MPDATA,EZ,5,,14050

MPDATA,PRXY,5,,0.29

MPDATA,PRYZ,5,,0.29

MPDATA,PRXZ,5,,0.6

MPDATA,GXY,5,,5127.5  

MPDATA,GYZ,5,,5127.5 

MPDATA,GXZ,5,,4390.6


TB, FCLI, 5, 1,9,1

!TBDATA,1,Xnt,Xnc,Ynt,Ync,Znt,Znc

!TBDATA,7,Shear,Shear,Shear

TBDATA,1,2400,2250,69,350,69,350

TBDATA,7,87,87,87


!Material Model of Epoxy adhesive of NSM

MP,EX, 6, 3400

MP,NUXY, 6,0.37

TB,MISO,6,1,2,0 

TBTEMP,0

TBPT,,0.0092,31.2

TBPT,,0.011,31.2 


ESEL,S,MAT,,1 !Select elements of concrete 

NSLE

NSEL,R,LOC,X,70,75  

NSEL,R,LOC,Y,22 

NSEL,R,LOC,Z,500,1600

CM,Target1,NODE 

!Target 1 represents the nodes of concrete adjectent to top layer of epoxy/groove


ESEL,S,MAT,,6

NSLE

NSEL,R,LOC,X,70,75  

NSEL,R,LOC,Y,22 

NSEL,R,LOC,Z,500,1600

CM,Conta1,NODE 

!Conta 1 represents the nodes of top layer of epoxy in groove


!Cohesive Zone Modelling

TB,CZM,CZM_MMODEL,1,,CBDE

!TBDATA,1,snmax,Gcn,stmax,Gct,ita,bita

!TBDATA,7,alfa

TBDATA,1,4,0.043,9.65,1.44,1 E-8,0

TBDATA,7,2


ET,8,170 !Define Target element

ET,9,174 !Define Contact element

R,31, !Defined real constant for contact

KEYOPT,9,9,1 !Exclude both initial geometrical penetration or gap and offset

KEYOPT,9,12,3 !Bonded Contact: I am using bonded contact because when i use other contact type, the analysis terminates earlier with error in element formulation


TYPE,9

REAL,31

CMSEL,S,CONTA1 

ESLN,S

ESURF          ! FORMING CONTACT ELEMENTS

ALLSEL,ALL

  

TYPE,8

REAL,31

CMSEL,S,TARGET1

ESLN,S

ESEL,R,MAT,,1 !elements of concrete, elements of discrete steel reinforcement was unnecessary selected and hence this command used

ESURF          ! FORMING TARGET ELEMENTS

ALLSEL,ALL


!Similarly Contact pair with same CZM material and different element no. and real constant was defined at left side of cross section of the groove


!Similarly Contact pair with same CZM material and different element no. and real constant was defined at common cross section of concrete and epoxy (beginning of groove in longitudinal direction)


!NOTE: The epoxy of groove is in contact with concrete in 5 sides (top, left, right,front and back, free only at the bottom). Only quarter of the beam is modeled and hence contact is defined in only three directions


!Script for load displacement curve

n_uy=NODE(75,0,1600) ! node at mid span where displacement is read


ALLSEL,ALL  

CMSEL,S,A1 ! A1 represents the nodes at which the displacement is applied as load


*GET, n_min, NODE, 0, NUM, MIN, , 


*GET, n_max, NODE, 0, NUM, MAX, , 


*GET, n_count, NODE, 0, COUNT, , ,


finish

/POST1

SET,LAST


finish

/POST26


NUMVAR, 200


ii=n_min


*do,i,1,n_count,1

rforce,2, ii,F,Y,FY

!ADD, 3, 3, 2,,FYT,,,,-0.002, !for half model

ADD, 3, 3, 2,,FYT,,,,-0.004, !for quarter model

!ii=NDNEXT(ii)

*GET, iii, NODE, ii, NXTH, , , 

ii=iii

*ENDDO

NSOL,4,n_uy,U,Y,UY

ABS,4,4,,,UY


/AXlab,X,displacement [mm]

/AXlab,Y,force [kN]

XVAR, 4

PLVAR, 3  

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