# findStructuralIC

Find initial displacement and velocity assigned to geometric region

## Description

example

sica = findStructuralIC(structuralmodel.InitialConditions,RegionType,RegionID) returns the initial displacement and velocity assigned to the specified region.

## Examples

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Find the initial displacement and velocity assigned to the cells of a 3-D geometry.

Create a transient dynamic model for a 3-D problem.

structuralmodel = createpde("structural","transient-solid");

Create the geometry consisting of the three nested cylinders and include it in the model. Plot the geometry.

gm = multicylinder([5 10 15],2);
structuralmodel = createpde("structural","transient-solid");
structuralmodel.Geometry = gm;
pdegplot(structuralmodel,"CellLabels","on","FaceAlpha",0.5)

Set the initial conditions for each cell. When you specify only the initial velocity or initial displacement, structuralIC assumes that the omitted parameter is zero.

structuralIC(structuralmodel,"Displacement",[0;0;0],...
"Velocity",[0;0;0], ...
"Cell",1);
structuralIC(structuralmodel,"Displacement",[0;0.1;0], ...
"Cell",2);
structuralIC(structuralmodel,"Velocity",[0;0.2;0], ...
"Cell",3);

Check the initial condition specification for cell 1.

SICACell1 = findStructuralIC(structuralmodel.InitialConditions,"Cell",1)
SICACell1 =
GeometricStructuralICs with properties:

RegionType: 'Cell'
RegionID: 1
InitialDisplacement: [3x1 double]
InitialVelocity: [3x1 double]

SICACell1.InitialDisplacement
ans = 3×1

0
0
0

SICACell1.InitialVelocity
ans = 3×1

0
0
0

Use a static solution as an initial condition for a dynamic structural model. Check and plot the initial displacement.

Create a static model.

staticmodel = createpde("structural","static-solid");

Create the geometry and include it in the model. Plot the geometry.

gm = multicuboid(0.06,0.005,0.01);
staticmodel.Geometry = gm;
pdegplot(staticmodel,"FaceLabels","on","FaceAlpha",0.5)
view(50,20)

Specify Young's modulus, Poisson's ratio, and the mass density.

structuralProperties(staticmodel,"YoungsModulus",210E9, ...
"PoissonsRatio",0.3,...
"MassDensity",7800);

Apply the boundary condition and static load.

structuralBC(staticmodel,"Face",5,"Constraint","fixed");
"SurfaceTraction",[0;1E6;0]);
generateMesh(staticmodel,"Hmax",0.02);
Rstatic = solve(staticmodel);

Create a dynamic model and assign geometry.

dynamicmodel = createpde("structural","transient-solid");
gm = multicuboid(0.06,0.005,0.01);
dynamicmodel.Geometry = gm;

Apply the boundary condition.

structuralBC(dynamicmodel,"Face",5,"Constraint","fixed");

Specify the initial condition using the static solution.

generateMesh(dynamicmodel,"Hmax",0.02);
structuralIC(dynamicmodel,Rstatic)
ans =
NodalStructuralICs with properties:

InitialDisplacement: [113x3 double]
InitialVelocity: [113x3 double]

Check the initial condition specification for dynamicmodel.

sica = findStructuralIC(dynamicmodel.InitialConditions,"Cell",1)
sica =
NodalStructuralICs with properties:

InitialDisplacement: [113x3 double]
InitialVelocity: [113x3 double]

Plot the z-component of the initial displacement.

pdeplot3D(dynamicmodel,"ColorMapData",sica.InitialDisplacement(:,3))
title("Initial Displacement in the Z-direction")

## Input Arguments

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Initial conditions of a transient structural model, specified as the InitialConditions property of a StructuralModel object.

Geometric region type, specified as "Face", "Edge", or "Vertex" for a 2-D model or 3-D model, or "Cell" for a 3-D model.

Data Types: char

Geometric region ID, specified as a vector of positive integers. Find the region IDs by using pdegplot.

Data Types: double

## Output Arguments

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Structural initial condition for a particular region, returned as a GeometricStructuralICs or NodalStructuralICs object. For details, see GeometricStructuralICs Properties and NodalStructuralICs Properties.

## Version History

Introduced in R2018a