Bracket modal analysis#

This example demonstrates a modal analysis on an L-shaped bracket using PyMechanical-MCP. The workflow extracts the first six natural frequencies and mode shapes to identify resonance risks.

Engineering objective#

Determine the first six natural frequencies and mode shapes of a five-millimeter thick L-shaped steel bracket. Identify the fundamental bending mode and higher-order twisting modes. Confirm natural frequencies are in the range of approximately 100 Hz to several kilohertz.

Geometry#

  • File: bracket.step

  • L-bracket dimensions: 100 millimeters vertical x 60 millimeters horizontal x 80 millimeters wide x 5 millimeters thick

  • Features: Two eight-millimeter mounting holes in the horizontal leg and one 15-millimeter hole in the vertical plate

Setup requirements#

Setting

Value

Material

Structural Steel (default)

Mesh

Element size is 3 millimeters for good mode-shape resolution

Fixed support

Cylindrical faces of the two mounting holes in the horizontal leg

Analysis type

Modal

Number of modes

First 6

Frequency range

0 to 10,000 hertz

Tool workflow#

  1. Connect to or launch Mechanical using connect_to_mechanical or launch_mechanical.

  2. Upload the bracket.step file using upload_file.

  3. Assign structural steel as the material to all bodies using run_python_script.

  4. Insert a modal analysis system and set the number of modes to six using run_python_script.

  5. Apply fixed supports to the bolt-hole cylindrical faces using run_python_script.

  6. Generate a three-millimeter element size mesh using run_python_script.

  7. Run the solver using solve_analysis.

  8. Retrieve and print natural frequencies using run_python_script.

  9. Capture a screenshot of Mode 1 (the fundamental mode) using screenshot.

Expected outcome#

  • Mode 1: Bending of the vertical plate (fundamental mode)

  • Modes 2 to 6: Progressive twisting and complex deformation patterns

  • Natural frequencies ranging from approximately 100 hertz to several kilohertz

Prompt example#

Perform a modal analysis on an L-shaped bracket to find the first 6 natural frequencies
and mode shapes. Upload the geometry file bracket.step.

- Material: Structural Steel (default)
- Mesh: element size 3 mm
- Fixed support on mounting hole cylindrical faces (horizontal leg)
- Modal analysis: first 6 modes, frequency range 0-10,000 Hz
- Results: Total Deformation for each mode, list of natural frequencies
- Take a screenshot of Mode 1 (fundamental mode)