General Mechanical

General Mechanical

Modeling a beam-to-surface contact by the Conta177&Targe170 elements.

    • manu87
      Subscriber

      Hi,everybody. Inspired by the example VM278 in ANSYS help, I'm working on the problem that a beam is located within a cylinder. The beam is modeled by the Pipe288 element, while the cylinder is regarded as a rigid surface and meshed by the Targe170 element. A contact pair is established between the beam and cylinder, using Conta177& Targe170 elements. The boundary condition at the both ends are treated as a pin. In the first step, the gravity and a axial compress force is loaded. Then a rotational displacement is applied at the left end. 


      However, it seems that the contact does not work, since the contact status and the penetration ara null. The beam deforms largely, and the radial displacement exceeds the extent of the cylinder.


      Anybody would offer some help?




      The APDL file is attached as follows.


      finish


      /clear


       


      /PREP7


      L=50 ! MODELING PARAMETERS


      OD=0.5


      WT=(0.5-0.4)/2


      !*** SOLID MODEL ***


      !



      k,1,L,, 


      K,2,


      K,3,L,,-0.8/2


      K,4,,,-0.8/2


      L,1,2 ! GEOMETRY OF THE BEAM 


      L,3,4


      AROTAT,2,,,,,,1,2,360,


       


      !*** MATERIAL PROPERTIES FOR STEEL IN NEWTONS AND METERS ***


      !



      MP,EX,1,2.1E11 ! YOUNG'S MODULUS


      MP,PRXY,1,0.3 ! POISSON'S RATIO


      MP,DENS,1,7800 ! DENSITY


      MP,MU,1,0.35 ! COEFFICIENT OF FRICTION


       


      !*** ELEMENT TYPES ***


      !



      ET,1,PIPE288 ! 3-D 3-NODE PIPE


      ET,2,170 ! 3-D TARGET SEGMENT


      ET,3,CONTA177 ! 3-D LINE-TO-SURFACE CONTACT


      KEYOPT,3,2,1 ! PENALTY FUNCTION ALGORITHM


      KEYOPT,3,3,2   ! TRACTION-BASED CONTACT TYPE


      KEYOPT,3,7,1


      KEYOPT,3,10,2


       


       


       


      !*** SECTION DATA ***


      !



      ! EXAMPLE SECTION:


      SECTYPE,1,PIPE,,PIPE1 ! DEFINE PIPE SECTION


      SECDATA,OD,WT,16 ! APPLY MODELING PARAMETERS TO PIPE SECTION


      ! *** REAL CONSTANTS ***


      !



      R,2,


      RMODIF,2,3,-1e10 ! ABSOLUTE VALUE OF PENALTY STIFFNESS


       


       


       


      ! *** MESHING ***


      !



      TYPE,1   


      MAT,1 


      SECNUM,1


      LESIZE,1,1,   


      LMESH,1


       


      *GET,dnodemax,node,,num,maxd


      /pnum,node,1


       


       


      asel,s,,,all


      TYPE,2


      REAL,2


      amesh,all


       


       


       


      ! CONTACT/TARGET


      TYPE,3 ! CONTACT TYPE


      REAL,2


      MAT,1


      LSEL,S,,,1


      ESLL


      ESURF ! PLACE CONTACT ON PIPE ELEMENTS


      esel,s,real,,2


      ESEL,r,TYPE,,2


      ESURF,,REVERSE  


       


       


      /pnum,node,0


      ALLSEL,ALL


      FINISH


       


       


      /SOLU


      ANTYPE,4 


      NLGEOM,1  


      ACEL,,9.8


      d,2,UX,,,,,UY,UZ


      ddele,2,ux


      f,2,fx,5e4


      d,1,UX,,,,,UY,UZ 


      KBC,0   


      AUTOTS,1   


      OUTRES,ALL,all 


      TIME,2  


      SOLVE


       


       


      kbc,0   


      *do,i,1/30,1,1/30


      d,2,rotx,6.28*i


      timint,on   


      TIME,2+i


      AUTOTS,1


      solve  


      *enddo


       

    • John Doyle
      Ansys Employee

      Try offsetting the beam slightly so the two are not perfectly concentric.


      Also, use refined time increments with DELTIM.

    • manu87
      Subscriber

      Sorry for the delaying reply.


      Thank you for your help. I tried your method, but it did not work.


      Then I reread the help document, and the help shows that "CONTA177 is used to represent contact and sliding between 3-D target surfaces and a deformable line segment, defined by this element. The element is applicable to 3-D beam-to-surface, 3-D shell edge-to-surface, and 3-D beam-to-beam (or edge-to-edge) structural contact analyses. ". It seems that the case of 3-D beam-to-surface and 3-D beam-to-beam are distinguished. So would be there a probability that CONTA177 is just used in a non-closed surface, such as a half cylinder, or a half sphere?

    • John Doyle
      Ansys Employee

      Are you modeling the target as a rigid surface?


      If so, I think your target element surface normals might be facing outward, so the contact elements are not seeing the target elements.


      Can you try using beam to beam contact?  See See Section 5.3.1 of Contact Technology Guide.


       

    • manu87
      Subscriber

      Yes, the target surface points outwards defaultly, and it had been adjusted by the command ESURF,,REVERSE. Then the contact/target elements are seeing each other.


      I'll try the second method you metioned. But, if any ideas you get about the CONTA177 element modeling, please contact me. Thank you.

Viewing 4 reply threads
  • You must be logged in to reply to this topic.