The torsional stiffness of a rollover protection structure (ROPS) is to be determined. The geometry of the example is shown in Figure 7. Unit force of ±1 kN are applied to constrained nodal rigid bodies in the corners of the lower longitudinal beams. Additional boundary conditions are applied to prevent large rigid body motions. The example keyword file is ROPS_linear_stiffness.key. The resulting displacement magnitude is shown in Figure 8.
Example Files: ROPS_linear_stiffness
NOTE! All examples are included in the Complete Guideline
*KEYWORD
$===============================================================================
$ Geometry
$===============================================================================
*INCLUDE
ROPS_geo.key
$===============================================================================
$ Control and output cards
$===============================================================================
*INCLUDE
../INCLUDE_FILES/control_cards_linear.key
*INCLUDE
../INCLUDE_FILES/database_cards_static.key
*CONTROL_TERMINATION
$ ENDTIM ENDCYC DTMIN ENDENG ENDMAS
1.
*CONTROL_MPP_IO_NODUMP
$===============================================================================
$ Contacts
$===============================================================================
*CONTACT_TIED_SHELL_EDGE_TO_SURFACE_CONSTRAINED_OFFSET_ID
$# cid title
101Tie 1
$# ssid msid sstyp mstyp sboxid mboxid spr mpr
11 3 4 2 0 0 0 0
$# fs fd dc vc vdc penchk bt dt
$# sfs sfm sst mst sfst sfmt fsf vsf
*CONTACT_TIED_SHELL_EDGE_TO_SURFACE_CONSTRAINED_OFFSET_ID
$# cid title
102Tie 2
$# ssid msid sstyp mstyp sboxid mboxid spr mpr
12 4 4 2 0 0 0 0
$# fs fd dc vc vdc penchk bt dt
$# sfs sfm sst mst sfst sfmt fsf vsf
$===============================================================================
$ Loading and boundary conditions
$===============================================================================
*DEFINE_CURVE_TITLE
Zero curve
1000
0., 0.
2., 0.
*BOUNDARY_PRESCRIBED_MOTION_RIGID
1001 1 2 1000
1001 2 2 1000
1001 5 2 1000
1001 6 2 1000
1001 7 2 1000
$
2001 1 2 1000
$
1002 1 2 1000
1002 2 2 1000
$
2002 1 2 1000
*DEFINE_CURVE_TITLE
Loading ramp
1001
0., 0.
1., 1.
2., 1.
*LOAD_RIGID_BODY
1001 3 1001 1.E3
2001 3 1001 -1.E3
1002 3 1001 -1.E3
2002 3 1001 1.E3
$===============================================================================
$ Additional output options
$===============================================================================
*DATABASE_HISTORY_NODE_SET
1 2 17 18
$===============================================================================
$ Simulation title
$===============================================================================
*TITLE
Linear stiffness of a ROPS
*END
*KEYWORD *INCLUDE *CONTROL_TERMINATION *CONTROL_MPP_IO_NODUMP *CONTACT_TIED_SHELL_EDGE_TO_SURFACE_CONSTRAINED_OFFSET_ID *DEFINE_CURVE_TITLE *BOUNDARY_PRESCRIBED_MOTION_RIGID *DEFINE_CURVE_TITLE *LOAD_RIGID_BODY *DATABASE_HISTORY_NODE_SET *TITLE *END