Skip to content

Latest commit

 

History

History

Tubes

Telescoping Tubes Under Bending Load

Tested with CGX 2.19 / CCX 2.19

  • Telescopic structure of linear elastic tubes
  • Loaded in pure bending (no shear)
  • Surface-to-surface contact
File Contents
pre.fbd Pre-processing script for CGX
post.fbd Post-processing script for cgx
solve.inp CCX input
moment.plt Gnuplot input for the moment-time-curve
test.py Python script to run the full simulation

Preprocessing

The tube axis goes along x. The outer tube is fixed at x = 0, the inner tube overlaps with the outer tube by OVL and is loaded with a prescribed rotation at the free end.

The parameters can be changed in pre.fbd.

Parameter Value Meaning
R1 50 radius of the outer tube in mm
T1 5 wall thickness of the outer tube in mm
L1 500 length of the outer tube in mm
R2 45 radius of the inner tube in mm
T2 5 wall thickness of the inner tube in mm
TL 500 length of the inner tube in mm
OVL 150 overlap in mm
divt 2 mesh division in thickness direction
divrot 18 mesh division in hoop direction
divl 100 mesh division in longitudinal direction
> cgx -b pre.fbd

The outer end of the inner tube (turquoise) is coupled in x and z direction to the rigid body motion controlled by node 1. This node is constrained in x direction to prevent rigid body motion of the tube and in y direction to prevent free translation of the node in y direction. The load is applied as prescribed rotation about the y axis.

The outer end of the outer tube is fixed (magenta). The nodes in the plane of symmetry (red) are constrained in y-direction.

Solving

A non-linear static step with initial increment of 10% is used.

> ccx solve
> monitor.py solve

Postprocessing

> cgx -b post.fbd

Equivalent stress

Contact pressure

Moment versus time. Time is proportional to the prescribed rotation. This curve is generated in post.fbd using the commands

> dat2txt.py
> gnuplot moment.plt