# This is an Abaqus Python script to extract data from an ODB file # Run with: abaqus python odb_to_json_v2.py import json from abaqusConstants import ELEMENT_NODAL, NODAL from odbAccess import openOdb # ------------------------ # USER INPUT # ------------------------ odb_path = "simulation.odb" output_json = "simulation.json" field_requests = ["U", "U_MAGNITUDE", "LE", "LE_MAX_PRINC", "S_VON_MISES"] # Extrapolation mode for element-based fields (only one option for now) extrapolation_mode = "element_nodal" # Step + frame selection # Use 'all' or a list per step, e.g ([5, -1]). -1 will include last frame. steps_selection = { "Step-1": "all", } # ------------------------ derived_fields_map = { "LE_MAX_PRINC": ("LE", lambda val: val.maxPrincipal), "LE_MID_PRINC": ("LE", lambda val: val.midPrincipal), "LE_MIN_PRINC": ("LE", lambda val: val.minPrincipal), "S_MAX_PRINC": ("S", lambda val: val.maxPrincipal), "S_MID_PRINC": ("S", lambda val: val.midPrincipal), "S_MIN_PRINC": ("S", lambda val: val.minPrincipal), "S_VON_MISES": ("S", lambda val: val.mises), "U_MAGNITUDE": ("U", lambda val: val.magnitude), } # ------------------------ # HELPER FUNCTIONS # ------------------------ def get_field_subset(field, inst, mode): native_pos = field.locations[0].position if native_pos == NODAL: return field.getSubset(region=inst) if mode == "element_nodal": return field.getSubset(region=inst, position=ELEMENT_NODAL) raise ValueError("Unknown extrapolation_mode: %s" % mode) def build_field_layout(field, inst, mode): native_pos = field.locations[0].position sub = get_field_subset(field, inst, mode) if not sub.values: return None if native_pos == NODAL: unique_labels = sorted(list(set([v.nodeLabel for v in sub.values]))) return { "location": "NODAL", "node_labels": unique_labels, } # ELEMENT-based fields location = "ELEMENT_NODAL" # only option for now by_type = {} for v in sub.values: elem = inst.getElementFromLabel(v.elementLabel) etype = elem.type if etype not in by_type: by_type[etype] = {"element_labels": set()} by_type[etype]["element_labels"].add(v.elementLabel) for etype in by_type: by_type[etype]["element_labels"] = sorted( list(by_type[etype]["element_labels"]) ) return { "location": location, "by_element_type": by_type, } # ------------------------ # MAIN LOGIC # ------------------------ odb = openOdb(odb_path) data = { "meta": { "job": odb_path, "extrapolation_mode": extrapolation_mode, "fields_requested": field_requests, }, "mesh": {}, "steps": {}, } # 1) Mesh Extraction for inst_name, inst in odb.rootAssembly.instances.items(): data["mesh"][inst_name] = { "node_labels": [n.label for n in inst.nodes], "undeformed_coords": [float(c) for n in inst.nodes for c in n.coordinates], "elements": {}, } for elem in inst.elements: etype = elem.type if etype not in data["mesh"][inst_name]["elements"]: data["mesh"][inst_name]["elements"][etype] = { "connectivity": [], "nplex": len(elem.connectivity), } data["mesh"][inst_name]["elements"][etype]["connectivity"].extend( [nid for nid in elem.connectivity] ) # 2) Step/Field Extraction for step_name, frame_selection in steps_selection.items(): if step_name not in odb.steps: print("Warning: Step '%s' not found." % step_name) continue step = odb.steps[step_name] total_frames = len(step.frames) if frame_selection == "all": frames_to_export = range(total_frames) else: frames_to_export = [f if f >= 0 else total_frames + f for f in frame_selection] step_data = { "frames_selected": list(frames_to_export), "field_layouts": {}, "frames": {}, } ref_frame = step.frames[frames_to_export[0]] # BUILD LAYOUTS for f_key in field_requests: base_name = ( derived_fields_map[f_key][0] if f_key in derived_fields_map else f_key ) if base_name not in ref_frame.fieldOutputs: continue field = ref_frame.fieldOutputs[base_name] step_data["field_layouts"][f_key] = {} for inst_name, inst in odb.rootAssembly.instances.items(): try: layout = build_field_layout(field, inst, extrapolation_mode) if layout: step_data["field_layouts"][f_key][inst_name] = layout except Exception as e: print( "Note: Field '%s' skipped for instance '%s': %s" % (f_key, inst_name, str(e)) ) # FRAME DATA EXTRACTION for idx in frames_to_export: frame = step.frames[idx] frame_data = {"time": float(frame.frameValue), "fields": {}} print("Processing Step: %s, Frame: %d" % (step_name, idx)) for f_key, inst_layouts in step_data["field_layouts"].items(): base_name, func = derived_fields_map.get(f_key, (f_key, None)) field = frame.fieldOutputs[base_name] frame_data["fields"][f_key] = {} for inst_name, layout in inst_layouts.items(): inst = odb.rootAssembly.instances[inst_name] sub_field = get_field_subset(field, inst, extrapolation_mode) val_dict = {} # Key: elementLabel, Value: {nodeLabel: [values]} for val in sub_field.values: e_lbl = val.elementLabel n_lbl = val.nodeLabel v_out = func(val) if func else val.data if layout["location"] == "NODAL": val_dict[n_lbl] = v_out else: # ELEMENT_NODAL logic if e_lbl not in val_dict: val_dict[e_lbl] = {} if n_lbl not in val_dict[e_lbl]: val_dict[e_lbl][n_lbl] = [] if isinstance(v_out, (float, int)): val_dict[e_lbl][n_lbl].append(float(v_out)) else: val_dict[e_lbl][n_lbl].extend([float(c) for c in v_out]) # Build final structure v_list = [] if layout["location"] == "NODAL": for nl in layout["node_labels"]: d = val_dict.get(nl, 0.0) if isinstance(d, (float, int)): v_list.append(float(d)) else: v_list.extend([float(c) for c in d]) else: field_by_type = {} for etype in sorted(layout["by_element_type"].keys()): type_values = [] for el in layout["by_element_type"][etype]["element_labels"]: # Get the connectivity for this specific element to maintain order elem_obj = inst.getElementFromLabel(el) for node_id in elem_obj.connectivity: # This ensures Node1(SNEG, SPOS), Node2(SNEG, SPOS)... node_vals = val_dict.get(el, {}).get(node_id, []) type_values.extend(node_vals) field_by_type[etype] = type_values v_list = field_by_type frame_data["fields"][f_key][inst_name] = v_list step_data["frames"][str(idx)] = frame_data data["steps"][step_name] = step_data with open(output_json, "w") as f: json.dump(data, f, separators=(",", ":")) print("\nDone. Results saved to: %s" % output_json) odb.close()