Abaqus Lhs Batch Dataset

Abaqus LHS Batch Dataset Generator

End-to-end workflow for producing FEA training datasets from a parameterized Abaqus model. Designed for surrogate model training (Ridge, MLP, Gaussian Process, etc.) where you need hundreds to thousands of FEA samples covering a design space.

When to Use This Skill

Activate when the user wants to:

• Build a training set for a surrogate / ML model from Abaqus FEA
• Sweep a multi-dimensional design vector (e.g. force amplitudes, geometry parameters, material properties)
• Run N independent Abaqus jobs in batch with progress tracking and crash recovery
• Generate inputs for inverse-design / topology-optimization pipelines

Do NOT use this skill for:

• Single-case Abaqus runs (use abaqus-job instead)
• Parametric sweeps that don't need ML-ready CSV output (use abaqus-job + manual analysis)
• Optimization loops where each evaluation depends on the previous one (use a different driver)

Core Pattern

template_dir/                       per-case_dir/                    dataset_root/
  ├ Parameters.dat       ──copy──>  ├ Parameters.dat                 ├ sample_design.csv  (the design matrix)
  ├ MaterialParams.dat              ├ MaterialParams.dat             ├ dataset_index.csv  (one row per case)
  ├ ChannelParams.dat               ├ ChannelParams.dat              ├ sample_00001/
  ├ InData.txt                      ├ InData.txt                     │   ├ ForceAmplitude.dat   <- NEW
  └ solver_script.py                ├ ForceAmplitude.dat   <- NEW    │   ├ Membrane2D1.odb
                                    ├ <run abaqus cae noGUI>         │   ├ node_displacement.csv
                                    ├ Membrane2D1.odb       <- new   │   ├ run_stdout.log
                                    ├ node_displacement.csv <- new   │   └ run_stderr.log
                                    └ run_*.log             <- new   ├ sample_00002/
                                                                     └ ...

The pattern is template-driven: you keep one canonical case with all the static input files (geometry, material, mesh, step parameters), and per sample you only overwrite the design vector file (e.g. ForceAmplitude.dat).

Required Inputs

The user must provide:

1. template_dir/ — A folder containing one working Abaqus case with all the static input files. Verify by running it once standalone and confirming the .odb is produced. Required files vary by setup, but typically include:

   • Parameters.dat — geometry (length, width, thickness, Es, μ)
   • StepParameters.dat — analysis step config (StepType, time, damping)
   • MaterialParameters.dat — material model
   • ChannelParameters.dat — design dimension (number of channels / patches / load regions)
   • InData.txt — driver flags (output mode, force-continuity flag)
   • Optional: PatchGrid2D.dat, DisturbParameters.dat

2. solver_script.py — The Abaqus/Python solver script that:

   • Reads the template .dat files
   • Reads the per-case design file (e.g. ForceAmplitude.dat)
   • Builds the model, submits the job, opens the ODB, and writes a per-node CSV (e.g. node_displacement.csv with columns frame_id, time, node_id, x0, y0, z0, ux, uy, uz, x_def, y_def, z_def)
   • Is invoked via abaqus cae noGUI="<path>" from inside the case dir

3. Design dimension D — number of free parameters per sample (e.g. 16 channels)

4. Sampling strategy + bounds (e.g. LHS in [-0.5, +0.5]^16)

Sampling Strategies

Pick one (or combine) based on the design space:

Combine them: a typical surrogate dataset uses 600 LHS + 200 sparse-k + 200 single-active = 1000 samples.

Workflow Steps

When the user invokes you, do this:

Step 1 — Read the template, validate

# Read ChannelParameters.dat → channel_num (= design dimension D)
# Read PatchGrid2D.dat (if present) → grid shape, boundary mode
# Verify all required files exist

Step 2 — Generate the design matrix

• Build a list of (design_id, vector) tuples per the chosen strategy
• Deduplicate (use a string key from the rounded values to drop near-duplicates)
• Write sample_design.csv with header design_id, active_count, amplitude_1, ..., amplitude_D

Step 3 — Per-sample case execution

For each sample i = 1..N:

1. case_dir = dataset_root / f"sample_{i:05d}"
2. Copy all files from template_dir/ into case_dir/ (shutil.copy2)
3. Overwrite ForceAmplitude.dat in case_dir/ with the new design vector — this is the only file that changes between cases. Format (Abaqus *Amplitude blocks):

   *Amplitude, name=Amplitude       1
       0.000000000000000,    -0.376581075439650
       1.000000000000000,    -0.376581075439650
   *Amplitude, name=Amplitude       2
       0.000000000000000,     0.123456789012345
       1.000000000000000,     0.123456789012345
   ...
   

   For static loads, the two-point amplitude is constant. For ramp loading, set (0, 0), (t_ramp, val), (1, val).
4. Run Abaqus with timeout via subprocess.run:

   subprocess.run(
       'abaqus cae noGUI="<solver_script>"',
       cwd=str(case_dir),
       shell=True,
       text=True,
       capture_output=True,
       timeout=timeout_s,  # default 3600
   )
   

5. Capture proc.returncode, proc.stdout → run_stdout.log, proc.stderr → run_stderr.log, elapsed time
6. Detect success: Membrane2D1.odb exists AND node_displacement.csv exists AND returncode == 0
7. Append a row to dataset_index.csv:

   sample_id, design_id, case_folder, channel_num, grid_nx, grid_ny,
   amplitude_1, ..., amplitude_D,
   max_abs_uz, status, odb_exists, csv_exists, return_code, elapsed_seconds, error_msg
   

Step 4 — Resume / retry support

• Before running a case, check if dataset_index.csv already has a completed row for that sample_id → skip if --reuse-existing
• For failed rows, optionally retry with longer timeout

Step 5 — Report

• Print summary: N completed / M total, mean elapsed = X s
• List failed sample IDs for manual inspection of run_stderr.log

Critical Implementation Details

1. Working directory MUST be the case dir

Abaqus reads *.dat files relative to the launch directory. Always set cwd=case_dir in subprocess.run. NEVER invoke the solver from the dataset root or template dir.

2. Abaqus must be on PATH

Verify with abaqus --help before starting. On Windows, the install adds C:\SIMULIA\Commands to PATH.

3. CPU contention

Each abaqus cae job uses 1 CPU by default. Running batch jobs serially is the simplest correct approach. For parallelism, ensure numCpus * concurrent_jobs ≤ physical_cores and watch out for license token contention.

4. Disk usage

Each case generates ~50-200 MB (.odb + .dat + .csv + lockfiles). For 1000 samples, plan for 100-200 GB. Optionally delete .odb and intermediate files after extracting the per-node CSV (see the abaqus-odb-to-grid-csv skill).

5. Failure modes (in order of frequency)

• License timeout: solver hangs waiting for a token → use Abaqus's lic_check_freq env var or detect via *** ERROR: TIMED OUT WAITING FOR LICENSE in stderr
• Convergence failure: nonlinear solve diverges (typical with extreme amplitudes) → status = "failed", check .msg file
• Mesh distortion: too-large displacements warp elements past Jacobian threshold → reduce amplitude bounds or refine mesh
• File lock / leftover .lck files: previous crashed run left *.lck → script should rm -f *.lck before submitting
• Time budget: a single case taking > timeout_s → mark as timeout, increase per-case budget for retry

6. Reproducibility

Always seed the RNG (random.Random(seed)) and write the seed to dataset_meta.json. LHS with the same seed + same N gives identical samples.

Reference Implementation

A complete, dependency-free Python implementation is in references/batch_runner.py (~400 lines). It's parameterized via argparse so it works as a CLI:

python batch_runner.py \
    --template-dir ./template_case \
    --solver-script ./MyAbaqusSolver.py \
    --dataset-root ./datasets \
    --strategy lhs \
    --n-samples 1000 \
    --bounds-min -0.5 \
    --bounds-max 0.5 \
    --seed 42 \
    --timeout-s 3600

The references/sampling.py module contains pure-stdlib LHS, sparse-k, single-active, pair-adj, and block-2x2 samplers.

Output Schema

After a complete run:

datasets/run_YYYYMMDD_HHMMSS/
├ sample_design.csv         # design_id, active_count, amplitude_1..D
├ dataset_index.csv         # sample_id, design_id, ..., status, return_code, elapsed
├ dataset_meta.json         # seed, strategy, bounds, template path, abaqus version
├ sample_00001/
│   ├ ForceAmplitude.dat    # the per-case design vector
│   ├ Parameters.dat        # (copied from template)
│   ├ ...other .dat files
│   ├ Membrane2D1.odb       # the FEA result
│   ├ Membrane2D1.msg       # solver log
│   ├ node_displacement.csv # per-node ux/uy/uz per frame
│   ├ input_vector.csv      # (channel_id, amplitude_value)
│   ├ sample_summary.csv    # geometry + step metadata
│   ├ run_stdout.log
│   └ run_stderr.log
├ sample_00002/
└ ...

The next step in the pipeline is typically the abaqus-odb-to-grid-csv skill, which collapses each node_displacement.csv into a single row of a wide-table Y_grid_uz.csv (sample_id × N²), giving you ML-ready (X, Y) matrices.

Quick Sanity Checks

After a run completes, ask the agent to verify:

1. Index integrity: pandas.read_csv("dataset_index.csv") — count status == "completed"
2. Sample diversity: max-pairwise-correlation of sample_design.csv rows — should be < 0.7 for LHS
3. Output range: dataset_index.csv["max_abs_uz"] distribution — should span at least 1 order of magnitude (else the design space is too narrow)
4. Failed cases: cat sample_XXXXX/run_stderr.log for the first 3 failures

If a high failure rate (> 5%) appears, narrow the design bounds or check the solver script — don't blindly retry.