liminfoAbaqus Reference
Free reference guide: Abaqus Reference
About Abaqus Reference
The Abaqus Reference is a searchable quick-reference for Dassault Systemes SIMULIA Abaqus, one of the most widely used finite element analysis (FEA) suites in automotive, aerospace, and civil engineering. It covers the keyword-driven .inp input file syntax that defines every aspect of an Abaqus simulation, from node and element definitions to material constitutive models, loading conditions, and solver configuration.
This reference organizes Abaqus keywords into six practical categories: Elements (C3D8R, S4R, B31, C3D10, CPE4), Material definitions (*ELASTIC, *PLASTIC, *HYPERELASTIC, *DENSITY), Loads and Boundary Conditions (*BOUNDARY, *CLOAD, *DLOAD, *TEMPERATURE, *CONTACT PAIR), Analysis procedures (*STATIC, *DYNAMIC EXPLICIT, *FREQUENCY, *HEAT TRANSFER), Output requests (*NODE FILE, *EL FILE, *OUTPUT FIELD), and Python scripting via mdb.models and session objects.
Each entry includes the exact keyword syntax, a concise description, and a copy-ready code example that can be pasted directly into an .inp file or Abaqus/CAE Python script. Whether you are setting up a nonlinear static analysis with large deformations, running an explicit crash simulation, performing a modal frequency extraction with the Lanczos solver, or automating post-processing with Python, this reference helps you recall the correct syntax without opening the full Abaqus documentation.
Key Features
- Complete element type reference including C3D8R hexahedral, S4R shell, B31 beam, C3D10 tetrahedral, and CPE4 plane strain elements
- Material model keywords for elastic, plastic, hyperelastic (Mooney-Rivlin), and density definitions with parameter formats
- Load and boundary condition syntax for concentrated loads (*CLOAD), distributed loads (*DLOAD, *DSLOAD), temperature fields, and contact pairs
- Analysis step configuration for static, dynamic explicit, natural frequency (Lanczos eigensolver), and steady-state heat transfer procedures
- Output request keywords for node results (U, RF), element results (S, E, PEEQ), and field output with PRESELECT variables
- Python scripting examples for mdb.models and session.viewports to automate model building and post-processing
- Syntax-highlighted .inp code blocks with custom Abaqus language grammar for accurate keyword, parameter, and value coloring
- Category-based filtering to quickly switch between Elements, Material, Loads/BCs, Analysis, Output, and Scripting sections
Frequently Asked Questions
What Abaqus element types are covered in this reference?
This reference covers the most commonly used element types: C3D8R (8-node reduced-integration hexahedral), S4R (4-node reduced-integration shell), B31 (2-node linear beam), C3D10 (10-node quadratic tetrahedral), and CPE4 (4-node plane strain). Each entry shows the *ELEMENT keyword with TYPE and ELSET parameters plus a node connectivity example.
How do I define a nonlinear material with plasticity in Abaqus?
Use the *MATERIAL keyword followed by *ELASTIC for the linear portion (Young's modulus and Poisson's ratio) and *PLASTIC for the hardening curve. The *PLASTIC data lines take pairs of yield stress and corresponding plastic strain. For example: *PLASTIC followed by data lines like 250., 0.0 and 400., 0.2 defines a bilinear hardening curve starting at 250 MPa yield.
What is the difference between *CLOAD and *DLOAD?
*CLOAD applies a concentrated (point) load at a specific node and degree of freedom, such as *CLOAD / LOAD_NODE, 2, -1000. for a 1000-unit force in the negative Y direction. *DLOAD applies a distributed body force or pressure over element faces, while *DSLOAD is specifically for surface-based distributed loads. Use *DSLOAD when you have defined a surface via *SURFACE.
How do I set up an explicit dynamic analysis in Abaqus?
Inside a *STEP block, use *DYNAMIC, EXPLICIT followed by the time period (e.g., , 0.001 for a 1 ms event). The explicit solver uses conditionally stable time increments based on element size and wave speed. Add NLGEOM=YES to the *STEP line if large deformations are expected, which is common in crash and impact simulations.
What is the Lanczos eigensolver used for in Abaqus?
The Lanczos eigensolver is invoked via *FREQUENCY, EIGENSOLVER=LANCZOS and is used for natural frequency (modal) extraction. You specify the number of eigenvalues to compute. It is the recommended eigensolver for large models and is more efficient than the subspace iteration method when a large number of modes are needed.
How do I request stress and displacement output in Abaqus?
Use *OUTPUT, FIELD, VARIABLE=PRESELECT for default output, or specify *NODE OUTPUT with U (displacement) and RF (reaction force), and *ELEMENT OUTPUT with S (stress), E (strain), and PEEQ (equivalent plastic strain). Legacy keywords *NODE FILE and *EL FILE also work for .fil file output. Field output goes to the .odb file for Abaqus/Viewer.
Can I automate Abaqus model creation with Python?
Yes. Abaqus/CAE exposes a full Python scripting interface. Access models via mdb.models['Model-1'], parts via model.parts['Part-1'], and the ODB for post-processing via session.viewports. Scripts can create geometry, assign materials, apply loads, submit jobs, and extract results. This reference includes syntax examples for both mdb and session objects.
What does the NLGEOM=YES parameter do on the *STEP keyword?
NLGEOM=YES activates geometric nonlinearity for the analysis step, meaning the solver accounts for large deformations, large rotations, and stress stiffening. Once turned on in a step, it remains active for all subsequent steps. It is essential for buckling analysis, hyperelastic rubber simulations, and any problem where displacements are large relative to the model dimensions.