Properties for Example 1

Command	Explanation
Program Control
control.runWhile = "t <= 30";	lets the control module (cf. main.cpp) terminate the simulation once the variable t (defaults to the current simulation time in seconds) has become greater than 30.
Solver Configuration
Solver.modules = [ "integrator" ];	defines the modules, that make up the solver. In our case it is only one, called integrator.
Solver.integrator.type = "MilneDevice";	defines the type of the integrator module, in our case it's a MilneDeviceModule (this type needs to agree with the name it is declared under in the ModuleFactory)
Solver.integrator.deltaTime = 5e-5;	set the starting time step size for the integrator to \(5 \times 10^{-5}\) seconds
Material Properties
params.rod_details.material.type = "ElasticRod";	define the type of the material to be ElasticRodMaterial
params.rod_details.material.cross_section = "square";	define the rod to be of square cross-section
params.rod_details.material.side_length = "sqrt(12/2e3)";	define the sides to be \(\sqrt{12/2e3}\approx0.0775\) (meter) long
params.rod_details.material.young = "5.6e10/12";	define the rods Young's modulus to be \(5.6e10/12\approx4.67e9\) (Pascal)
params.rod_details.material.shear_modulus = 2e9;	define the rods shear modulus to be \(2e9\) (Pascal)
params.rod_details.material.density = 200.;	define the rod to have a density of \(200\) (kilogram/meter³)
File Includes
include "input.pro";	include the input.pro file defining input modules and geometry reading
include "model.pro";	include the model.pro file defining the physical model
include "output.pro";	include the output.pro file defining output modules and data collection
Additional Settings
Input.input.order = 2;	set the interpolation order for the input elements to 2 (quadratic elements)
Force Model Override
model.model.force.type = "None";	override the force model from model.pro to have no applied forces
Displacement Boundary Conditions
model.model.disp.type = "LoadScale";	set the displacement boundary condition to use load scaling (LoadScaleModel) (in dynamic simulations displacement prescribtions are prescribing accelerations)
model.model.disp.scaleFunc = "if (t<15, 6/15 * (1 - cos(2*PI/15 * t)), 0)";	define a time-dependent scaling function: a single sinusoidal half-wave during the first 15s
model.model.disp.model.type = "Dirichlet";	specify that the displacement model uses Dirichlet boundary conditions (DirichletModel) (they will apply to the acceleration in the dynamic solves)
model.model.disp.model.nodeGroups = [ "fixed" ];	apply the displacement (acceleration) boundary condition to the "fixed" node group
model.model.disp.model.factors = [ 1. ];	set the scaling factor for the displacement (acceleration) to 1.0
model.model.disp.model.dofs = [ "rz" ];	apply the displacement (acceleration) boundary condition to the rz (rotation about z-axis) degree of freedom
CSV Output Configuration
Output.disp.type = "Sample";	override the output type from output.pro to use sampling output (SampleModule)
Output.disp.file = "$(CASE_NAME)/disp.gz";	specify the output file path using the case name variable, compressed with gzip
Output.disp.dataSets = [ "free.disp.dx", "free.disp.dy", "free.disp.dz", "free.disp.rx", "free.disp.ry", "free.disp.rz" ];	define the datasets to output: all displacement and rotation components for the "free" node group
Output.disp.dataSets += "fixed.disp.rz";	append the rz displacement of the "fixed" node group to the output datasets
Output.disp.dataSets += "t";	append the time variable to the output datasets
Output.disp.separator = ",";	set the CSV separator character to comma
ParaView Visualization Output
Output.modules += "paraview";	add a ParaView output module to the existing output modules
Output.paraview.type = "ParaView";	specify the module type as ParaViewModule visualization output
Output.paraview.output_format = "$(CASE_NAME)/visual/step%i";	set the output format with case name and step numbering
Output.paraview.groups = [ "beams" ];	define the groups to include in ParaView output (beams)
Output.paraview.beams.shape = "Line3";	specify that beams should be visualized as 3D line elements
Output.paraview.beams.disps = model.model.rodMesh.child.dofNamesTrans;	include translational displacement fields in the ParaView output
Output.paraview.beams.otherDofs = model.model.rodMesh.child.dofNamesRot;	include rotational degree of freedom fields in the ParaView output
Output.paraview.beams.node_data = ["fint", "fext", "fres"];	specify node data to output: internal forces, external forces, and residual forces
Output.paraview.beams.el_data = ["strain", "stress", "mat_stress", "mat_strain"];	specify element data to output: strain, stress, material stress, and material strain
Output.paraview.sampleWhen = "t % 0.1 < deltaTime";	set the sampling condition: output when time modulo 0.1 is less than the time step size (every 0.1 seconds)

input.pro

The input.pro file defines the input modules responsible for reading geometry and defining node groups. Here are the line-by-line explanations:

Command	Explanation
Input Module Configuration
Input.modules = [ "input", "groupInput" ];	define the input modules: "input" for geometry reading and "groupInput" for node group creation
Geometry Input Settings
Input.input.type = "GMSHInput";	specify that the input module is a GMSHInputModule
Input.input.file = "$(CASE_NAME).geo";	set the geometry file path using the case name variable with .geo extension
Node Group Definition
Input.groupInput.type = "GroupInput";	specify that the groupInput module is a GroupInputModule
Input.groupInput.nodeGroups = [ "fixed", "free" ];	define two node groups: "fixed" and "free"
Fixed Group Criteria
Input.groupInput.fixed.xtype = "min";	nodes in "fixed" group have minimum x-coordinate values
Input.groupInput.fixed.ytype = "min";	nodes in "fixed" group have minimum y-coordinate values
Input.groupInput.fixed.ztype = "min";	nodes in "fixed" group have minimum z-coordinate values
Free Group Criteria
Input.groupInput.free.xtype = "max";	nodes in "free" group have maximum x-coordinate values
Input.groupInput.free.ytype = "max";	nodes in "free" group have maximum y-coordinate values
Input.groupInput.free.ztype = "max";	nodes in "free" group have maximum z-coordinate values

model.pro

The model.pro file defines the physical model and boundary conditions. Here are the line-by-line explanations:

Command	Explanation
Model Structure
model.type = "Matrix";	define the top-level model type as MatrixModel
model.model.type = "Multi";	specify that the model contains multiple sub-models (MultiModel)
model.model.models = [ "rodMesh", "fixed", "force", "disp" ];	define the four sub-models: rod mesh, fixed boundaries, forces, and displacements
Rod Mesh Configuration
model.model.rodMesh.type = "Lattice";	specify the rod mesh as a LatticeModel (for beam/rod networks)
model.model.rodMesh.prefix = "beam_";	set the prefix for beam element names to "beam_"
model.model.rodMesh.child.type = "specialCosseratRod";	define individual rod elements as SpecialCosseratRodModel
model.model.rodMesh.child.dofNamesTrans = ["dx", "dy", "dz"];	define translational degrees of freedom: x, y, z displacements
model.model.rodMesh.child.dofNamesRot = ["rx", "ry", "rz"];	define rotational degrees of freedom: rotations about x, y, z axes
model.model.rodMesh.child += params.rod_details;	inherit additional rod properties from the params.rod_details defined in main file
Fixed Boundary Conditions
model.model.fixed.type = "Dirichlet";	specify the fixed boundary conditions to use the DirichletModel
model.model.fixed.maxDisp = 0.;	set maximum displacement limit to 0 (fully constrained)
model.model.fixed.dispIncr = 0.;	set displacement increment to 0 (no movement allowed)
model.model.fixed.nodeGroups = [ "fixed", "fixed", "fixed" ];	apply constraints to "fixed" node group for all three translational DOFs
model.model.fixed.dofs = model.model.rodMesh.child.dofNamesTrans;	constrain all translational degrees of freedom (dx, dy, dz)
model.model.fixed.factors = [ 0., 0., 0. ];	set constraint factors to 0 for all translational DOFs (no movement)
model.model.fixed.nodeGroups += [ "fixed", "fixed", "fixed" ];	extend constraints to rotational DOFs for the same node group
model.model.fixed.dofs += model.model.rodMesh.child.dofNamesRot;	add rotational degrees of freedom (rx, ry, rz) to constraints
model.model.fixed.factors += [ 0., 0., 0. ];	set constraint factors to 0 for all rotational DOFs (no rotation)
Force Boundary Conditions
model.model.force.type = "Neumann";	specify the force boundary conditions to use the NeumannModel
model.model.force.initLoad = 0.;	set initial load value to 0
model.model.force.loadIncr = 0.;	set load increment to 0 (no force applied by default)
model.model.force.nodeGroups = [ "fixed" ];	apply force boundary condition to "fixed" node group
model.model.force.factors = [ 0. ];	set force scaling factor to 0 (no force applied)
model.model.force.dofs = [ "dx" ];	specify that force is applied in x-direction
Displacement Boundary Conditions
model.model.disp.type = "Dirichlet";	specify the prescribed displacements to use the DirichletModel
model.model.disp.initDisp = 0.;	set initial displacement to 0
model.model.disp.dispIncr = 0.;	set displacement increment to 0 (no prescribed displacement by default)
model.model.disp.nodeGroups = [ "fixed" ];	apply displacement boundary condition to "fixed" node group
model.model.disp.factors = [ 0. ];	set displacement scaling factor to 0 (no prescribed displacement)
model.model.disp.dofs = [ "dx" ];	specify that displacement is prescribed in x-direction

output.pro

The output.pro file defines the output modules for data collection and logging. Here are the line-by-line explanations:

Command	Explanation
Output Module Configuration
Output.modules = [ "loadextent", "disp" ];	define two output modules: "loadextent" for force tracking and "disp" for displacement data
Load Extent Output
Output.loadextent.type = "GroupOutput";	use the GroupOutputModule to extract data from the output groups
Output.loadextent.nodeGroups = [ "fixed", "free" ];	track data for both "fixed" and "free" node groups
Output.loadextent.dofs = model.model.rodMesh.child.dofNamesTrans;	include translational degrees of freedom (dx, dy, dz) in output
Output.loadextent.dofs += model.model.rodMesh.child.dofNamesRot;	add rotational degrees of freedom (rx, ry, rz) to output
Output.loadextent.dimensions = model.model.rodMesh.child.dofNamesTrans;	specify spatial dimensions for output based on translational DOFs
Displacement CSV Output
Output.disp.type = "CSVOutput";	use the CSVOutputModule to output the collected data
Output.disp.file = "$(CASE_NAME)/disp.gz";	set output file path with case name and gzip compression
Output.disp.vectors = [ "state = disp" ];	output displacement state vectors
Logging Configuration
log.pattern = "*";	set logging pattern to capture all log messages (wildcard pattern)
log.file = "-";	direct log output to standard output (console) using "-"