# Modeling bolt connection with preloaded beam element

**URL:** <https://prepomax.discourse.group/t/modeling-bolt-connection-with-preloaded-beam-element/1412>\
**Category:** General Questions\
**Created:** [January 14, 2024, 10:26am UTC](https://prepomax.discourse.group/t/modeling-bolt-connection-with-preloaded-beam-element/1412 "2024-01-14T10:26:26Z")\
**Posts on this page:** 1\
**Showing post:** 5

<div class="post-metadata">

**Author:** ![FEAnalyst](https://yyz2.discourse-cdn.com/free1/user_avatar/prepomax.discourse.group/feanalyst/32/688_2.png) [@FEAnalyst](https://prepomax.discourse.group/u/FEAnalyst)\
**Post date:** [January 14, 2024, 5:25pm UTC](https://prepomax.discourse.group/t/modeling-bolt-connection-with-preloaded-beam-element/1412/5 "2024-01-14T17:25:21Z")

</div>

\*CLOAD should be applied to the reference node of the pre-tension section. Maybe there’s an issue with the way those beam elements are attached to the solid model. CalculiX documentation suggests distributing coupling and equation constraints for that. There’s a simple example that you can try first:

```auto
**
** Structure: bolt-like structure.
** Test objective: pre-tension force with beam element.
**
*NODE, NSET=Nall
       1,0.000000000000e+00,0.000000000000e+00,0.000000000000e+00
       2,0.000000000000e+00,1.000000000000e+00,0.000000000000e+00
       3,2.000000000000e-01,1.000000000000e+00,0.000000000000e+00
       4,2.000000000000e-01,0.000000000000e+00,0.000000000000e+00
       5,1.414213562373e-01,0.000000000000e+00,-1.414213562373e-01
       6,1.414213562373e-01,1.000000000000e+00,-1.414213562373e-01
       7,1.000000000000e+00,1.000000000000e+00,0.000000000000e+00
       8,1.000000000000e+00,0.000000000000e+00,0.000000000000e+00
       9,7.071067811865e-01,0.000000000000e+00,-7.071067811865e-01
      10,7.071067811865e-01,1.000000000000e+00,-7.071067811865e-01
      11,2.000000000000e-01,5.000000000000e-01,0.000000000000e+00
      12,1.847759065023e-01,0.000000000000e+00,-7.653668647302e-02
      13,1.414213562373e-01,5.000000000000e-01,-1.414213562373e-01
      14,1.847759065023e-01,1.000000000000e+00,-7.653668647302e-02
      15,6.000000000000e-01,1.000000000000e+00,0.000000000000e+00
      16,6.000000000000e-01,0.000000000000e+00,0.000000000000e+00
      17,4.242640687119e-01,0.000000000000e+00,-4.242640687119e-01
      18,4.242640687119e-01,1.000000000000e+00,-4.242640687119e-01
      19,1.000000000000e+00,5.000000000000e-01,0.000000000000e+00
      20,9.238795325113e-01,0.000000000000e+00,-3.826834323651e-01
      21,7.071067811865e-01,5.000000000000e-01,-7.071067811865e-01
      22,9.238795325113e-01,1.000000000000e+00,-3.826834323651e-01
      23,2.775557561563e-17,0.000000000000e+00,-2.000000000000e-01
      24,2.775557561563e-17,1.000000000000e+00,-2.000000000000e-01
      25,2.220446049250e-16,0.000000000000e+00,-1.000000000000e+00
      26,2.220446049250e-16,1.000000000000e+00,-1.000000000000e+00
      27,7.653668647302e-02,0.000000000000e+00,-1.847759065023e-01
      28,2.775557561563e-17,5.000000000000e-01,-2.000000000000e-01
      29,7.653668647302e-02,1.000000000000e+00,-1.847759065023e-01
      30,1.249000902703e-16,0.000000000000e+00,-6.000000000000e-01
      31,1.249000902703e-16,1.000000000000e+00,-6.000000000000e-01
      32,3.826834323651e-01,0.000000000000e+00,-9.238795325113e-01
      33,2.220446049250e-16,5.000000000000e-01,-1.000000000000e+00
      34,3.826834323651e-01,1.000000000000e+00,-9.238795325113e-01
      35,-1.414213562373e-01,0.000000000000e+00,-1.414213562373e-01
      36,-1.414213562373e-01,1.000000000000e+00,-1.414213562373e-01
      37,-7.071067811865e-01,0.000000000000e+00,-7.071067811865e-01
      38,-7.071067811865e-01,1.000000000000e+00,-7.071067811865e-01
      39,-7.653668647302e-02,0.000000000000e+00,-1.847759065023e-01
      40,-1.414213562373e-01,5.000000000000e-01,-1.414213562373e-01
      41,-7.653668647302e-02,1.000000000000e+00,-1.847759065023e-01
      42,-4.242640687119e-01,0.000000000000e+00,-4.242640687119e-01
      43,-4.242640687119e-01,1.000000000000e+00,-4.242640687119e-01
      44,-3.826834323651e-01,0.000000000000e+00,-9.238795325113e-01
      45,-7.071067811865e-01,5.000000000000e-01,-7.071067811865e-01
      46,-3.826834323651e-01,1.000000000000e+00,-9.238795325113e-01
      47,-2.000000000000e-01,0.000000000000e+00,-8.326672684689e-17
      48,-2.000000000000e-01,1.000000000000e+00,-8.326672684689e-17
      49,-1.000000000000e+00,0.000000000000e+00,-2.775557561563e-16
      50,-1.000000000000e+00,1.000000000000e+00,-2.775557561563e-16
      51,-1.847759065023e-01,0.000000000000e+00,-7.653668647302e-02
      52,-2.000000000000e-01,5.000000000000e-01,-8.326672684689e-17
      53,-1.847759065023e-01,1.000000000000e+00,-7.653668647302e-02
      54,-6.000000000000e-01,0.000000000000e+00,-1.804112415016e-16
      55,-6.000000000000e-01,1.000000000000e+00,-1.804112415016e-16
      56,-9.238795325113e-01,0.000000000000e+00,-3.826834323651e-01
      57,-1.000000000000e+00,5.000000000000e-01,-2.775557561563e-16
      58,-9.238795325113e-01,1.000000000000e+00,-3.826834323651e-01
      59,-1.414213562373e-01,0.000000000000e+00,1.414213562373e-01
      60,-1.414213562373e-01,1.000000000000e+00,1.414213562373e-01
      61,-7.071067811865e-01,0.000000000000e+00,7.071067811865e-01
      62,-7.071067811865e-01,1.000000000000e+00,7.071067811865e-01
      63,-1.847759065023e-01,0.000000000000e+00,7.653668647302e-02
      64,-1.414213562373e-01,5.000000000000e-01,1.414213562373e-01
      65,-1.847759065023e-01,1.000000000000e+00,7.653668647302e-02
      66,-4.242640687119e-01,0.000000000000e+00,4.242640687119e-01
      67,-4.242640687119e-01,1.000000000000e+00,4.242640687119e-01
      68,-9.238795325113e-01,0.000000000000e+00,3.826834323651e-01
      69,-7.071067811865e-01,5.000000000000e-01,7.071067811865e-01
      70,-9.238795325113e-01,1.000000000000e+00,3.826834323651e-01
      71,-1.110223024625e-16,0.000000000000e+00,2.000000000000e-01
      72,-1.110223024625e-16,1.000000000000e+00,2.000000000000e-01
      73,-4.440892098501e-16,0.000000000000e+00,1.000000000000e+00
      74,-4.440892098501e-16,1.000000000000e+00,1.000000000000e+00
      75,-7.653668647302e-02,0.000000000000e+00,1.847759065023e-01
      76,-1.110223024625e-16,5.000000000000e-01,2.000000000000e-01
      77,-7.653668647302e-02,1.000000000000e+00,1.847759065023e-01
      78,-2.775557561563e-16,0.000000000000e+00,6.000000000000e-01
      79,-2.775557561563e-16,1.000000000000e+00,6.000000000000e-01
      80,-3.826834323651e-01,0.000000000000e+00,9.238795325113e-01
      81,-4.440892098501e-16,5.000000000000e-01,1.000000000000e+00
      82,-3.826834323651e-01,1.000000000000e+00,9.238795325113e-01
      83,1.414213562373e-01,0.000000000000e+00,1.414213562373e-01
      84,1.414213562373e-01,1.000000000000e+00,1.414213562373e-01
      85,7.071067811865e-01,0.000000000000e+00,7.071067811865e-01
      86,7.071067811865e-01,1.000000000000e+00,7.071067811865e-01
      87,7.653668647302e-02,0.000000000000e+00,1.847759065023e-01
      88,1.414213562373e-01,5.000000000000e-01,1.414213562373e-01
      89,7.653668647302e-02,1.000000000000e+00,1.847759065023e-01
      90,4.242640687119e-01,0.000000000000e+00,4.242640687119e-01
      91,4.242640687119e-01,1.000000000000e+00,4.242640687119e-01
      92,3.826834323651e-01,0.000000000000e+00,9.238795325113e-01
      93,7.071067811865e-01,5.000000000000e-01,7.071067811865e-01
      94,3.826834323651e-01,1.000000000000e+00,9.238795325113e-01
      95,1.847759065023e-01,0.000000000000e+00,7.653668647302e-02
      96,1.847759065023e-01,1.000000000000e+00,7.653668647302e-02
      97,9.238795325113e-01,0.000000000000e+00,3.826834323651e-01
      98,9.238795325113e-01,1.000000000000e+00,3.826834323651e-01
99,0.,0.,0.
100,0.,0.,0.
101,0.,0.,0.
*ELEMENT, TYPE=B31, ELSET=Ebeam
     1, 1, 2
*ELEMENT, TYPE=C3D20R, ELSET=Evol
     2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12,
          13, 14, 19, 20, 21, 22, 15, 16, 17, 18
     3, 6, 5, 23, 24, 10, 9, 25, 26, 13, 27,
          28, 29, 21, 32, 33, 34, 18, 17, 30, 31
     4, 24, 23, 35, 36, 26, 25, 37, 38, 28, 39,
          40, 41, 33, 44, 45, 46, 31, 30, 42, 43
     5, 36, 35, 47, 48, 38, 37, 49, 50, 40, 51,
          52, 53, 45, 56, 57, 58, 43, 42, 54, 55
     6, 48, 47, 59, 60, 50, 49, 61, 62, 52, 63,
          64, 65, 57, 68, 69, 70, 55, 54, 66, 67
     7, 60, 59, 71, 72, 62, 61, 73, 74, 64, 75,
          76, 77, 69, 80, 81, 82, 67, 66, 78, 79
     8, 72, 71, 83, 84, 74, 73, 85, 86, 76, 87,
          88, 89, 81, 92, 93, 94, 79, 78, 90, 91
     9, 84, 83, 4, 3, 86, 85, 8, 7, 88, 95,
          11, 96, 93, 97, 19, 98, 91, 90, 16, 15
*ELEMENT,TYPE=DCOUP3D,ELSET=Ecoup1
10,100
*ELEMENT,TYPE=DCOUP3D,ELSET=Ecoup2
11,101
*MATERIAL,NAME=EL
*ELASTIC
210000.,.3
*SOLID SECTION,ELSET=Evol,MATERIAL=EL
*BEAM SECTION,ELSET=Ebeam,MATERIAL=EL,SECTION=RECT
0.001,0.001
0.,0.,1.
*PRE-TENSION SECTION,ELEMENT=1,NODE=99
0.,1.,0.
*NSET,NSET=FIX
49,68,61,80,73,92,85,97,8,20,9,32,25,44,37,56
*NSET,NSET=Ncoup1
5,12,4,95,83,87,71,75,59,63,47,51,35,39,23,27
*NSET,NSET=Ncoup2
6,14,3,96,84,89,72,77,60,65,48,53,36,41,24,29
*BOUNDARY
FIX,1,3
*DISTRIBUTING COUPLING,ELSET=Ecoup1
Ncoup1,1.
*DISTRIBUTING COUPLING,ELSET=Ecoup2
Ncoup2,1.
*EQUATION
2
100,1,1.,1,1,-1.
2
100,2,1.,1,2,-1.
2
100,3,1.,1,3,-1.
*EQUATION
2
101,1,1.,2,1,-1.
2
101,2,1.,2,2,-1.
2
101,3,1.,2,3,-1.
*STEP
*STATIC
*CLOAD
99,1,1.
*NODE PRINT,NSET=Nall
U
*NODE PRINT,NSET=Ncoup1,TOTALS=YES
RF
*NODE PRINT,NSET=Ncoup2,TOTALS=YES
RF
*END STEP

```

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