feat: Add E11 Part Mass extractor, document pyNastran mass accuracy issue
New E11 Part Mass Extractor: - Add nx_journals/extract_part_mass_material.py - NX journal using NXOpen.MeasureManager.NewMassProperties() for accurate geometry-based mass - Add optimization_engine/extractors/extract_part_mass_material.py - Python wrapper that reads JSON output from journal - Add E11 entry to extractors/catalog.json Documentation Updates: - SYS_12_EXTRACTOR_LIBRARY.md: Add mass accuracy warning noting pyNastran get_mass_breakdown() under-reports ~7% on hex-dominant meshes with tet/pyramid fill elements. E11 (geometry .prt) should be preferred over E4 (BDF) unless material is overridden at FEM level. - 01_CHEATSHEET.md: Add mass extraction tip V14 Config: - Expand design variable bounds (blank_backface_angle max 4.5°, whiffle_triangle_closeness max 80mm, whiffle_min max 60mm) Testing showed: - E11 from .prt: 97.66 kg (accurate - matches NX GUI) - E4 pyNastran get_mass_breakdown(): 90.73 kg (~7% under-reported) 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
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Antoine
@@ -34,5 +34,19 @@
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"metric": "total"
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},
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"signature": "2f58f241a96afb1f"
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},
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"e11_part_mass_material": {
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"name": "extract_part_mass_material",
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"filename": "extract_part_mass_material.py",
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"action": "extract_part_mass_material",
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"domain": "cad_extraction",
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"description": "Extract mass, volume, surface area, CoG, and material from NX .prt files via NXOpen.MeasureManager",
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"params": {
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"result_type": "part_mass",
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"metric": "total",
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"requires_journal": "nx_journals/extract_part_mass_material.py"
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},
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"signature": "e11_part_mass_material",
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"notes": "Requires running NX journal first: run_journal.exe nx_journals/extract_part_mass_material.py <prt_file> -args <prt_path> <output_dir>"
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}
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}
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276
optimization_engine/extractors/extract_part_mass_material.py
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276
optimization_engine/extractors/extract_part_mass_material.py
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"""
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Extract Part Mass and Material Properties from NX Part Files
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This extractor reads mass and material data from a temp file written by
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the NX journal: nx_journals/extract_part_mass_material.py
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The journal uses NXOpen.MeasureManager to extract:
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- Mass (kg)
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- Volume (mm^3)
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- Surface area (mm^2)
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- Center of gravity (mm)
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- Material name and density
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NX Open APIs Used (by journal):
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- NXOpen.MeasureManager.NewMassProperties()
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- NXOpen.MeasureBodies
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- NXOpen.Body.GetBodies()
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- NXOpen.PhysicalMaterial
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Author: Atomizer
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Created: 2025-12-05
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Version: 1.0
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"""
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from pathlib import Path
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from typing import Dict, Any, Optional, Union
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import json
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def extract_part_mass_material(
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prt_file: Union[str, Path],
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properties_file: Optional[Union[str, Path]] = None
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) -> Dict[str, Any]:
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"""
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Extract mass and material properties from NX part file.
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This function reads from a temp JSON file that must be created by
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running the NX journal: nx_journals/extract_part_mass_material.py
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Args:
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prt_file: Path to .prt file (used to locate temp file)
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properties_file: Optional explicit path to _temp_part_properties.json
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If not provided, looks in same directory as prt_file
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Returns:
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Dictionary containing:
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- 'mass_kg': Mass in kilograms (float)
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- 'mass_g': Mass in grams (float)
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- 'volume_mm3': Volume in mm^3 (float)
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- 'surface_area_mm2': Surface area in mm^2 (float)
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- 'center_of_gravity_mm': [x, y, z] in mm (list)
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- 'moments_of_inertia': {'Ixx', 'Iyy', 'Izz', 'unit'} or None
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- 'material': {'name', 'density', 'density_unit'} (dict)
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- 'num_bodies': Number of solid bodies (int)
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Raises:
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FileNotFoundError: If prt file or temp properties file not found
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ValueError: If temp file has invalid format or extraction failed
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Example:
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>>> result = extract_part_mass_material('model.prt')
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>>> print(f"Mass: {result['mass_kg']:.3f} kg")
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Mass: 1.234 kg
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>>> print(f"Material: {result['material']['name']}")
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Material: Aluminum_6061
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Note:
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Before calling this function, you must run the NX journal to
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create the temp file:
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```
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run_journal.exe extract_part_mass_material.py model.prt
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```
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"""
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prt_file = Path(prt_file)
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if not prt_file.exists():
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raise FileNotFoundError(f"Part file not found: {prt_file}")
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# Determine properties file location
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if properties_file:
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props_file = Path(properties_file)
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else:
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props_file = prt_file.parent / "_temp_part_properties.json"
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if not props_file.exists():
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raise FileNotFoundError(
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f"Part properties temp file not found: {props_file}\n"
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f"Run the NX journal first:\n"
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f" run_journal.exe extract_part_mass_material.py {prt_file}"
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)
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# Read and parse JSON
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try:
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with open(props_file, 'r') as f:
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data = json.load(f)
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except json.JSONDecodeError as e:
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raise ValueError(f"Invalid JSON in properties file: {e}")
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# Check for extraction errors
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if not data.get('success', False):
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error_msg = data.get('error', 'Unknown error during extraction')
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raise ValueError(f"NX extraction failed: {error_msg}")
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# Build result dictionary
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result = {
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'mass_kg': float(data.get('mass_kg', 0.0)),
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'mass_g': float(data.get('mass_g', 0.0)),
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'volume_mm3': float(data.get('volume_mm3', 0.0)),
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'surface_area_mm2': float(data.get('surface_area_mm2', 0.0)),
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'center_of_gravity_mm': data.get('center_of_gravity_mm', [0.0, 0.0, 0.0]),
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'moments_of_inertia': data.get('moments_of_inertia'),
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'material': data.get('material', {'name': None, 'density': None, 'density_unit': 'kg/mm^3'}),
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'num_bodies': int(data.get('num_bodies', 0)),
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'part_file': data.get('part_file', prt_file.name),
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}
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print(f"[OK] Part mass: {result['mass_kg']:.6f} kg ({result['mass_g']:.2f} g)")
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if result['material'].get('name'):
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print(f"[OK] Material: {result['material']['name']}")
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return result
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def extract_part_mass(
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prt_file: Union[str, Path],
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properties_file: Optional[Union[str, Path]] = None
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) -> float:
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"""
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Convenience function to extract just the mass in kg.
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Args:
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prt_file: Path to .prt file
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properties_file: Optional explicit path to temp file
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Returns:
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Mass in kilograms (float)
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Example:
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>>> mass = extract_part_mass('model.prt')
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>>> print(f"Mass: {mass:.3f} kg")
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Mass: 1.234 kg
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"""
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result = extract_part_mass_material(prt_file, properties_file)
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return result['mass_kg']
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def extract_part_material(
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prt_file: Union[str, Path],
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properties_file: Optional[Union[str, Path]] = None
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) -> Dict[str, Any]:
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"""
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Convenience function to extract just material info.
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Args:
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prt_file: Path to .prt file
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properties_file: Optional explicit path to temp file
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Returns:
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Dictionary with 'name', 'density', 'density_unit'
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Example:
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>>> mat = extract_part_material('model.prt')
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>>> print(f"Material: {mat['name']}, Density: {mat['density']}")
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Material: Steel_304, Density: 7.93e-06
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"""
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result = extract_part_mass_material(prt_file, properties_file)
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return result['material']
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class PartMassExtractor:
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"""
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Class-based extractor for part mass and material with caching.
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Use this when you need to extract properties from multiple parts
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or want to cache results.
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Example:
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>>> extractor = PartMassExtractor('model.prt')
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>>> result = extractor.extract()
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>>> print(result['mass_kg'])
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1.234
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"""
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def __init__(
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self,
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prt_file: Union[str, Path],
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properties_file: Optional[Union[str, Path]] = None
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):
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"""
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Initialize the extractor.
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Args:
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prt_file: Path to .prt file
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properties_file: Optional explicit path to temp file
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"""
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self.prt_file = Path(prt_file)
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self.properties_file = Path(properties_file) if properties_file else None
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self._cached_result = None
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def extract(self, use_cache: bool = True) -> Dict[str, Any]:
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"""
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Extract mass and material properties.
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Args:
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use_cache: If True, returns cached result if available
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Returns:
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Dictionary with all extracted properties
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"""
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if use_cache and self._cached_result is not None:
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return self._cached_result
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self._cached_result = extract_part_mass_material(
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self.prt_file,
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self.properties_file
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)
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return self._cached_result
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@property
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def mass_kg(self) -> float:
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"""Get mass in kg (extracts if needed)."""
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return self.extract()['mass_kg']
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@property
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def mass_g(self) -> float:
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"""Get mass in grams (extracts if needed)."""
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return self.extract()['mass_g']
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@property
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def material_name(self) -> Optional[str]:
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"""Get material name (extracts if needed)."""
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return self.extract()['material'].get('name')
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@property
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def density(self) -> Optional[float]:
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"""Get material density in kg/mm^3 (extracts if needed)."""
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return self.extract()['material'].get('density')
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def clear_cache(self):
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"""Clear the cached result."""
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self._cached_result = None
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if __name__ == "__main__":
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import sys
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if len(sys.argv) < 2:
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print(f"Usage: python {sys.argv[0]} <prt_file> [properties_file]")
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sys.exit(1)
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prt_file = Path(sys.argv[1])
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props_file = Path(sys.argv[2]) if len(sys.argv) > 2 else None
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try:
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result = extract_part_mass_material(prt_file, props_file)
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print("\n" + "="*50)
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print("PART MASS & MATERIAL EXTRACTION RESULTS")
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print("="*50)
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print(f"Part File: {result['part_file']}")
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print(f"Mass: {result['mass_kg']:.6f} kg ({result['mass_g']:.2f} g)")
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print(f"Volume: {result['volume_mm3']:.2f} mm^3")
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print(f"Surface Area: {result['surface_area_mm2']:.2f} mm^2")
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print(f"Center of Gravity: {result['center_of_gravity_mm']} mm")
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print(f"Num Bodies: {result['num_bodies']}")
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if result['material']['name']:
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print(f"Material: {result['material']['name']}")
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if result['material']['density']:
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print(f"Density: {result['material']['density']} {result['material']['density_unit']}")
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if result['moments_of_inertia']:
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moi = result['moments_of_inertia']
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print(f"Moments of Inertia: Ixx={moi['Ixx']}, Iyy={moi['Iyy']}, Izz={moi['Izz']} {moi['unit']}")
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except Exception as e:
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print(f"\nERROR: {e}")
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import traceback
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traceback.print_exc()
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sys.exit(1)
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