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A tip load is applied to a cantilevered beam made of shell elements. The tip of the beam is constrained to be rigid.
Introduction
LS-DYNA Implicit Workshop
Problem #3: Rigid Tip
Objective
* Learn the limitations of a linear approximation using a simple example.
Problem Description
A tip load is applied to a cantilevered beam made of shell elements. The tip of the
beam is constrained to be rigid.
Procedure
Copy the input file to your local directory Using an editor, view the input file and
answer the following questions:
1. How is the rigid tip modeled?
2. How long is the beam?
Run the simulation using the original input file.
3. What type of analysis was performed?
4. What is the tip deflection?
5. What is the angle of rotation of the rigid body (Note: rotations in the RBDOUT file
are given in radians)?
6. What is the maximum X-stress at the supported end?
7. What is the maximum X-stress in the rigid elements?
Copy the input file to a new directory. Modify the input
file to perform a nonlinear analysis, and re-run the simulation.
8. What is the tip deflection?
9. What is the angle of rotation of the rigid body?
10. What is the maximum X-stress at the supported end?
11. What is the maximum X-stress in the rigid elements?
Copy the input file to a new directory. Modify the input file to again perform a linear
analysis, but with the constrained nodal rigid body removed. Run the simulation.
12. What is the tip deflection?
13. What is the maximum X-stress at the supported end?
14. What is the maximum X-stress in the tip elements?
Why does stress develop in the rigid elements during the linear analysis? (Hint: plot
the (axial) X-displacement along the length of the beam for each simulation.)
Keywords
*BOUNDARY_SPC_NODE
*CONSTRAINED_NODAL_RIGID_BODY
*CONTROL_IMPLICIT_GENERAL
*CONTROL_IMPLICIT_SOLUTION
*CONTROL_TERMINATION
*DATABASE_BINARY_D3PLOT
*DATABASE_RBDOUT
*DEFINE_CURVE
*ELEMENT_SHELL
*END
*KEYWORD
*LOAD_NODE_POINT
*MAT_ELASTIC
*NODE
*PART
*SECTION_SHELL
*SET_NODE_LIST
*TITLE
*KEYWORD
$
*TITLE
cantilevered shell strip w/ nodal rigid body end
$
$--------------
$
*CONTROL_TERMINATION
$# endtim endcyc dtmin endeng endmas
1.000000 0 0.0 0.0 0.0
$
$--------------
$
*CONTROL_IMPLICIT_GENERAL
$# imflag dt0 imform nsbs igs cnstn form
1 1.000000
$
*CONTROL_IMPLICIT_SOLUTION
$# nsolvr ilimit maxref dctol ectol rctol lstol
1 0 0 0.0 0.0 0.0 0.0
$# dnorm diverg istif nlprint nlnorm
0 0 0 0 0
$
$--------------
$
*DATABASE_RBDOUT
$# dt binary
1.000000
$
*DATABASE_BINARY_D3PLOT
$# dt lcdt beam npltc
1.000000
$
$--------------
$
*CONSTRAINED_NODAL_RIGID_BODY
$# pid cid nsid pnode iprt drflag rrflag
99 0 1
$
*SET_NODE_LIST
$# sid da1 da2 da3 da4
1 0.0 0.0 0.0 0.0
$# nid1 nid2 nid3 nid4 nid5 nid6 nid7 nid8
15 31 32 16 14 30 46 47
48
$
$--------------
$
*BOUNDARY_SPC_NODE
$# nid cid dofx dofy dofz dofrx dofry dofrz
1 0 1 1 1 1 1 1
17 0 1 1 1 1 1 1
33 0 1 1 1 1 1 1
$
$--------------
$
*LOAD_NODE_POINT
$# nid dof lcid sf cid m1 m2 m3
16 2 1 0.500000
32 2 1 1.000000
48 2 1 0.500000
$
*DEFINE_CURVE
$# lcid sidr sfa sfo offa offo dattyp
1 0 0.0 0.0 0.0 0.0
$# a1 o1
0.0 0.0
1.00000000 5.00000000
2.00000000 5.00000000
$
$--------------
$
*PART
$# title
cantilevered shell
$# pid secid mid eosid hgid grav adpopt tmid
1 1 1
$
*SECTION_SHELL
$# secid elform shrf nip propt qr/irid icomp setyp
1 21 0.833300 3 3 0.0
$# t1 t2 t3 t4 nloc marea
0.100000 0.100000 0.100000 0.100000 0 0.0
$
*MAT_ELASTIC
$# mid ro e pr da db not used
17.0000e-043.0000e+07 0.300000 0.0 0.0 0.0
$
*PART
$# title
cantilevered shell
$# pid secid mid eosid hgid grav adpopt tmid
2 1 2
$
*MAT_ELASTIC
$# mid ro e pr da db not used
27.0000e-043.0000e+07 0.300000 0.0 0.0 0.0
$
$--------------
$
*END
Animated Result
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