feat: Comprehensive expression extraction and OP2 result extractor example
Enhanced expression extraction to find ALL named expressions in .prt files, not just specific format. Added pyNastran-based result extraction example. Expression Extraction Improvements: - Updated regex to handle all NX expression format variations: * #(Type [units]) name: value; * (Type [units]) name: value; * *(Type [units]) name: value; * ((Type [units]) name: value; - Added Root:expression_name: pattern detection - Finds expressions even when value is not immediately available - Deduplication to avoid duplicates - Filters out NX internal names Test Results with Bracket.prt: - Previously: 1 expression (tip_thickness only) - Now: 5 expressions found: * support_angle = 30.0 degrees * tip_thickness = 20.0 mm * p3 = 10.0 mm * support_blend_radius = 10.0 mm * p11 (reference found, value unknown) OP2 Result Extraction (pyNastran): - Created example extractor: op2_extractor_example.py - Functions for common optimization metrics: * extract_max_displacement() - max displacement magnitude on any node * extract_max_stress() - von Mises or max principal stress * extract_mass() - total mass and center of gravity - Handles multiple element types (CQUAD4, CTRIA3, CTETRA, etc.) - Returns structured JSON for optimization engine integration - Command-line tool for testing with real OP2 files Usage: python optimization_engine/result_extractors/op2_extractor_example.py <file.op2> Integration Ready: - pyNastran already in requirements.txt - Result extractor pattern established - Can be used as template for custom metrics Next Steps: - Integrate result extractors into MCP tool framework - Add safety factor calculations - Support for thermal, modal results
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Claude
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optimization_engine/result_extractors/op2_extractor_example.py
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optimization_engine/result_extractors/op2_extractor_example.py
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"""
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Example: Result Extraction from OP2 files using pyNastran
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This shows how to extract optimization metrics from Nastran OP2 files.
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Common metrics:
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- Max displacement (for stiffness constraints)
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- Max von Mises stress (for strength constraints)
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- Mass (for minimization objectives)
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"""
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from pathlib import Path
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from typing import Dict, Any
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import numpy as np
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def extract_max_displacement(op2_path: Path) -> Dict[str, Any]:
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"""
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Extract maximum displacement magnitude from OP2 file.
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Args:
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op2_path: Path to .op2 file
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Returns:
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Dictionary with max displacement, node ID, and components
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"""
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from pyNastran.op2.op2 import OP2
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op2 = OP2()
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op2.read_op2(str(op2_path))
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# Get first subcase (usually the only one in static analysis)
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subcase_id = list(op2.displacements.keys())[0]
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displacements = op2.displacements[subcase_id]
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# Extract node IDs and displacement data
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node_ids = displacements.node_gridtype[:, 0].astype(int)
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disp_data = displacements.data[0] # First (and usually only) timestep
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# Calculate magnitude: sqrt(dx^2 + dy^2 + dz^2)
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dx = disp_data[:, 0]
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dy = disp_data[:, 1]
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dz = disp_data[:, 2]
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magnitudes = np.sqrt(dx**2 + dy**2 + dz**2)
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# Find max
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max_idx = np.argmax(magnitudes)
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max_displacement = magnitudes[max_idx]
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max_node_id = node_ids[max_idx]
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return {
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'max_displacement': float(max_displacement),
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'max_node_id': int(max_node_id),
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'dx': float(dx[max_idx]),
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'dy': float(dy[max_idx]),
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'dz': float(dz[max_idx]),
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'units': 'mm', # NX typically uses mm
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'subcase': subcase_id
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}
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def extract_max_stress(op2_path: Path, stress_type: str = 'von_mises') -> Dict[str, Any]:
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"""
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Extract maximum stress from OP2 file.
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Args:
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op2_path: Path to .op2 file
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stress_type: 'von_mises' or 'max_principal'
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Returns:
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Dictionary with max stress, element ID, and location
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"""
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from pyNastran.op2.op2 import OP2
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op2 = OP2()
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op2.read_op2(str(op2_path))
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# Stress can be in different tables depending on element type
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# Common: cquad4_stress, ctria3_stress, ctetra_stress, etc.
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stress_tables = [
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'cquad4_stress',
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'ctria3_stress',
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'ctetra_stress',
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'chexa_stress',
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'cbar_stress',
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'cbeam_stress'
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]
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max_stress_overall = 0.0
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max_element_id = None
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max_element_type = None
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for table_name in stress_tables:
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if hasattr(op2, table_name):
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stress_table = getattr(op2, table_name)
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if stress_table:
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subcase_id = list(stress_table.keys())[0]
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stress_data = stress_table[subcase_id]
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# Extract von Mises stress
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# Note: Structure varies by element type
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element_ids = stress_data.element_node[:, 0].astype(int)
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if stress_type == 'von_mises':
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# von Mises is usually last column
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stresses = stress_data.data[0, :, -1] # timestep 0, all elements, last column
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else:
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# Max principal stress (second-to-last column typically)
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stresses = stress_data.data[0, :, -2]
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max_stress_in_table = np.max(stresses)
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if max_stress_in_table > max_stress_overall:
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max_stress_overall = max_stress_in_table
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max_idx = np.argmax(stresses)
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max_element_id = element_ids[max_idx]
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max_element_type = table_name.replace('_stress', '')
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return {
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'max_stress': float(max_stress_overall),
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'stress_type': stress_type,
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'element_id': int(max_element_id) if max_element_id else None,
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'element_type': max_element_type,
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'units': 'MPa', # NX typically uses MPa
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}
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def extract_mass(op2_path: Path) -> Dict[str, Any]:
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"""
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Extract total mass from OP2 file.
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Args:
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op2_path: Path to .op2 file
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Returns:
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Dictionary with mass and center of gravity
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"""
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from pyNastran.op2.op2 import OP2
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op2 = OP2()
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op2.read_op2(str(op2_path))
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# Mass is in grid_point_weight table
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if hasattr(op2, 'grid_point_weight') and op2.grid_point_weight:
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mass_data = op2.grid_point_weight
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# Total mass
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total_mass = mass_data.mass.sum()
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# Center of gravity
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cg = mass_data.cg
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return {
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'total_mass': float(total_mass),
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'cg_x': float(cg[0]),
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'cg_y': float(cg[1]),
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'cg_z': float(cg[2]),
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'units': 'kg'
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}
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else:
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# Fallback: Mass not directly available
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return {
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'total_mass': None,
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'note': 'Mass data not found in OP2 file. Ensure PARAM,GRDPNT,0 is in Nastran deck'
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}
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# Combined extraction function for optimization
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def extract_all_results(op2_path: Path) -> Dict[str, Any]:
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"""
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Extract all common optimization metrics from OP2 file.
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Args:
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op2_path: Path to .op2 file
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Returns:
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Dictionary with all results
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"""
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results = {
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'op2_file': str(op2_path),
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'status': 'success'
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}
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try:
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results['displacement'] = extract_max_displacement(op2_path)
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except Exception as e:
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results['displacement'] = {'error': str(e)}
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try:
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results['stress'] = extract_max_stress(op2_path)
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except Exception as e:
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results['stress'] = {'error': str(e)}
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try:
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results['mass'] = extract_mass(op2_path)
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except Exception as e:
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results['mass'] = {'error': str(e)}
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return results
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# Example usage
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if __name__ == "__main__":
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import sys
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import json
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if len(sys.argv) < 2:
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print("Usage: python op2_extractor_example.py <path_to_op2_file>")
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sys.exit(1)
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op2_path = Path(sys.argv[1])
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if not op2_path.exists():
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print(f"Error: File not found: {op2_path}")
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sys.exit(1)
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print(f"Extracting results from: {op2_path}")
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print("=" * 60)
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results = extract_all_results(op2_path)
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print("\nResults:")
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print(json.dumps(results, indent=2))
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# Summary
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print("\n" + "=" * 60)
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print("SUMMARY:")
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if 'displacement' in results and 'max_displacement' in results['displacement']:
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disp = results['displacement']
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print(f" Max Displacement: {disp['max_displacement']:.6f} {disp['units']} at node {disp['max_node_id']}")
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if 'stress' in results and 'max_stress' in results['stress']:
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stress = results['stress']
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print(f" Max {stress['stress_type']}: {stress['max_stress']:.2f} {stress['units']} in element {stress['element_id']}")
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if 'mass' in results and 'total_mass' in results['mass'] and results['mass']['total_mass']:
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mass = results['mass']
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print(f" Total Mass: {mass['total_mass']:.6f} {mass['units']}")
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