feat: Add AtomizerField training data export and intelligent model discovery

Major additions:
- Training data export system for AtomizerField neural network training
- Bracket stiffness optimization study with 50+ training samples
- Intelligent NX model discovery (auto-detect solutions, expressions, mesh)
- Result extractors module for displacement, stress, frequency, mass
- User-generated NX journals for advanced workflows
- Archive structure for legacy scripts and test outputs
- Protocol documentation and dashboard launcher

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

optimization_engine/extractors/extract_von_mises_stress.py

@@ -0,0 +1,105 @@
+"""
+Extract maximum von Mises stress from structural analysis
+Auto-generated by Atomizer Phase 3 - pyNastran Research Agent
+
+Pattern: solid_stress
+Element Type: CTETRA
+Result Type: stress
+API: model.ctetra_stress[subcase] or model.chexa_stress[subcase]
+"""
+
+from pathlib import Path
+from typing import Dict, Any
+import numpy as np
+from pyNastran.op2.op2 import OP2
+
+
+def extract_solid_stress(op2_file: Path, subcase: int = 1, element_type: str = 'ctetra'):
+    """Extract stress from solid elements."""
+    from pyNastran.op2.op2 import OP2
+    import numpy as np
+
+    model = OP2()
+    model.read_op2(str(op2_file))
+
+    # Get stress object for element type
+    # Different element types have different stress attributes
+    stress_attr_map = {
+        'ctetra': 'ctetra_stress',
+        'chexa': 'chexa_stress',
+        'cquad4': 'cquad4_stress',
+        'ctria3': 'ctria3_stress'
+    }
+
+    stress_attr = stress_attr_map.get(element_type.lower())
+    if not stress_attr:
+        raise ValueError(f"Unknown element type: {element_type}")
+
+    # Access stress through op2_results container
+    # pyNastran structure: model.op2_results.stress.cquad4_stress[subcase]
+    stress_dict = None
+
+    if hasattr(model, 'op2_results') and hasattr(model.op2_results, 'stress'):
+        stress_container = model.op2_results.stress
+        if hasattr(stress_container, stress_attr):
+            stress_dict = getattr(stress_container, stress_attr)
+
+    if stress_dict is None:
+        raise ValueError(f"No {element_type} stress results in OP2. Available attributes: {[a for a in dir(model) if 'stress' in a.lower()]}")
+
+    # stress_dict is a dictionary with subcase IDs as keys
+    available_subcases = list(stress_dict.keys())
+    if not available_subcases:
+        raise ValueError(f"No stress data found in OP2 file")
+
+    # Use the specified subcase or first available
+    if subcase in available_subcases:
+        actual_subcase = subcase
+    else:
+        actual_subcase = available_subcases[0]
+
+    stress = stress_dict[actual_subcase]
+
+    itime = 0
+
+    # Extract von Mises if available
+    if stress.is_von_mises:  # Property, not method
+        # Different element types have von Mises at different column indices
+        # Shell elements (CQUAD4, CTRIA3): 8 columns, von Mises at column 7
+        # Solid elements (CTETRA, CHEXA): 10 columns, von Mises at column 9
+        ncols = stress.data.shape[2]
+
+        if ncols == 8:
+            # Shell elements - von Mises is last column
+            von_mises_col = 7
+        elif ncols >= 10:
+            # Solid elements - von Mises is column 9
+            von_mises_col = 9
+        else:
+            # Unknown format, try last column
+            von_mises_col = ncols - 1
+
+        von_mises = stress.data[itime, :, von_mises_col]
+        max_stress = float(np.max(von_mises))
+
+        # Get element info
+        element_ids = [eid for (eid, node) in stress.element_node]
+        max_stress_elem = element_ids[np.argmax(von_mises)]
+
+        return {
+            'max_von_mises': max_stress,
+            'max_stress_element': int(max_stress_elem)
+        }
+    else:
+        raise ValueError("von Mises stress not available")
+
+
+if __name__ == '__main__':
+    # Example usage
+    import sys
+    if len(sys.argv) > 1:
+        op2_file = Path(sys.argv[1])
+        result = extract_solid_stress(op2_file)
+        print(f"Extraction result: {result}")
+    else:
+        print("Usage: python {sys.argv[0]} <op2_file>")