Overview
The model_viewer() function launches an interactive graphical interface to visualize structural models, including geometry, loads, deformed shapes, and internal force diagrams.
Function Signature
from milcapy import model_viewer
model_viewer(model: SystemModel) -> None
Parameters
The structural model to visualize. The model must have been solved (analyzed) before calling this function.
Description
The model_viewer() function provides an interactive window for exploring structural analysis results. It is equivalent to calling model.show() on a SystemModel instance.
Features
The model viewer provides:
- Model Geometry: Displays nodes, members, trusses, and finite elements
- Support Visualization: Shows restraints and boundary conditions
- Load Display: Visualizes point loads and distributed loads
- Deformed Shape: Shows displacement magnification with customizable scale
- Internal Forces: Displays axial force, shear force, and bending moment diagrams
- Reactions: Shows support reactions
- Interactive Controls: Pan, zoom, and toggle display options
- Multiple Load Patterns: Switch between different load cases
Usage
Basic Usage
from milcapy import SystemModel, model_viewer, BeamTheoriesType
# Create and solve model
model = SystemModel()
# Define materials and sections
model.add_material("steel", modulus_elasticity=2.0e5, poisson_ratio=0.3)
model.add_rectangular_section("beam", "steel", base=0.3, height=0.4)
# Build model
model.add_node(1, 0, 0)
model.add_node(2, 5, 0)
model.add_member(1, 1, 2, "beam", BeamTheoriesType.TIMOSHENKO)
# Apply boundary conditions and loads
model.add_restraint(1, True, True, True)
model.add_restraint(2, False, True, False)
model.add_load_pattern("Live Load")
model.add_point_load(2, "Live Load", fy=-100)
# Solve the model
model.solve()
# Launch viewer
model_viewer(model)
Alternative: Using model.show()
# These are equivalent
model_viewer(model)
model.show()
Requirements
The model must be solved before calling model_viewer(). If the model has not been analyzed, the function will print a warning and return without opening the viewer.
# This will fail - model not solved
model = SystemModel()
model.add_node(1, 0, 0)
model_viewer(model) # Warning: No analyzed load patterns
# Correct usage
model = SystemModel()
model.add_node(1, 0, 0)
model.add_load_pattern("Load")
model.solve() # Must solve first
model_viewer(model) # Opens viewer successfully
Viewer Interface
The interactive viewer window provides several controls:
Display Options
- Nodes: Toggle node visibility and labels
- Members: Toggle member visibility and labels
- Supports: Show/hide support symbols
- Loads: Display point and distributed loads
- Deformed Shape: Show displaced configuration
- Internal Forces: Display force diagrams
Load Pattern Selection
Switch between different load patterns to compare results:
model.add_load_pattern("Dead Load")
model.add_load_pattern("Live Load")
model.add_load_pattern("Wind Load")
model.solve()
# Viewer allows switching between all three load patterns
model_viewer(model)
Examples
Viewing a Simple Frame
from milcapy import SystemModel, model_viewer, BeamTheoriesType
model = SystemModel()
# Material and section
model.add_material("concrete", 2.1e6, 0.2)
model.add_rectangular_section("col", "concrete", 0.3, 0.3)
# Frame nodes
model.add_node(1, 0, 0)
model.add_node(2, 0, 3)
model.add_node(3, 4, 3)
model.add_node(4, 4, 0)
# Members
model.add_member(1, 1, 2, "col", BeamTheoriesType.TIMOSHENKO)
model.add_member(2, 2, 3, "col", BeamTheoriesType.TIMOSHENKO)
model.add_member(3, 3, 4, "col", BeamTheoriesType.TIMOSHENKO)
# Supports
model.add_restraint(1, True, True, True)
model.add_restraint(4, True, True, True)
# Loads
model.add_load_pattern("Lateral")
model.add_point_load(2, "Lateral", fx=50)
# Solve and view
model.solve()
model_viewer(model)
Viewing Membrane Elements
from milcapy import SystemModel, model_viewer, ConstitutiveModelType
model = SystemModel()
# Material and shell section
model.add_material("concrete", 2.1e6, 0.2)
model.add_shell_section("wall", "concrete", thickness=0.2)
# Create mesh nodes
model.add_node(1, 0, 0)
model.add_node(2, 1, 0)
model.add_node(3, 1, 1)
model.add_node(4, 0, 1)
# Add membrane element
model.add_membrane_q6i(
id=1,
node_i_id=1,
node_j_id=2,
node_k_id=3,
node_l_id=4,
section_name="wall",
state=ConstitutiveModelType.PLANE_STRESS
)
# Supports and loads
model.add_restraint(1, True, True, False)
model.add_restraint(2, True, True, False)
model.add_load_pattern("Pressure")
model.add_point_load(3, "Pressure", fx=100)
model.add_point_load(4, "Pressure", fx=100)
# Solve and view
model.solve()
model_viewer(model)
Comparing Multiple Load Cases
from milcapy import SystemModel, model_viewer, BeamTheoriesType
model = SystemModel()
model.add_material("steel", 2.0e5, 0.3)
model.add_rectangular_section("beam", "steel", 0.2, 0.3)
model.add_node(1, 0, 0)
model.add_node(2, 6, 0)
model.add_member(1, 1, 2, "beam", BeamTheoriesType.TIMOSHENKO)
model.add_restraint(1, True, True, True)
model.add_restraint(2, False, True, False)
# Multiple load patterns
model.add_load_pattern("Dead Load", self_weight_multiplier=1.0)
model.add_load_pattern("Live Load")
model.add_distributed_load(1, "Live Load", -20, -20)
model.add_load_pattern("Point Load")
model.add_point_load(2, "Point Load", fy=-50)
# Solve all patterns
model.solve()
# Viewer allows switching between Dead, Live, and Point Load cases
model_viewer(model)
Return Value
The function does not return a value. It opens an interactive window that blocks execution until closed.
Notes
- The viewer window is modal and will block Python execution until closed
- Multiple load patterns can be viewed by switching between them in the interface
- The viewer automatically calculates appropriate scaling for deformations
- Use the pan and zoom tools to explore large models
For automated plotting or non-interactive visualization, use model.plot_model() instead, which creates a matplotlib figure that can be saved to a file.
See Also
