Prestrain

Prestrain Wrapper

Wraps a uniaxial host material model so that a prestrain can be applied. This may be useful for modelling prestressed reinforced concrete or similar multiphase materials.

Syntax

material Prestrain (1) (2) (3) (4)
# (1) int, unique material tag
# (2) int, underlying material tag
# (3) int, amplitude tag, set to 0 to use a ramp function
# (4) double, maginutde

Remarks

It is necessary to attach an amplitude. The amplitude is in charge of applying the designated prestrain (of the specified magnitude) to the underlying material in a controlled manner.

If only a prestress is available, one can always develop a uniaxial test model to compute the prestrain from the prestress. Thus, we do not provide a Prestress counterpart.

Example

node 1 0 0
node 2 1 0

material Elastic1D 1 100
material Prestrain 2 1 0 1E-2

element T2D2 1 1 2 1 10
element T2D2 2 1 2 2 10

fix2 1 1 1
fix2 2 2 1 2

step static 1
set ini_step_size .1

converger AbsIncreDisp 1 1E-4 10 1

analyze

peek node 2

exit

The above example is a simple demonstration. The prestrain \(0.01\) will be gradually (linearly increasing from zero to the specific magnitude) applied to the second element. The system balances itself without any external load.

The final displacement of node 2 should be \(0.005\) since both elements share the same section properties.