Abaqus FEA Software

Abaqus uses a flexible token-based licensing system to allocate computational resources for simulations. The number of tokens required depends on the type of solver, the number of CPU cores, and whether GPU acceleration is used. Use our Abaqus token calculator to find out how many tokens you’ll need. If you want to understand how the system works, the following explains token pooling, minimum token requirements, and benefits of the token system:

Token pooling:

• Abaqus licenses are based on a shared pool of tokens that can be used across multiple products, including Abaqus/Standard, Abaqus/Explicit, Tosca, fe-safe, and Isight.
• This unified token pool increases efficiency by allowing users to access multiple tools without needing separate licenses for each.

Minimum token requirements:

• A minimum of 5 tokens is required to run a simulation on a single CPU core.
• Additional tokens are needed as more CPU cores or GPUs are added to reduce computational time.
• With extended token licensing in Abaqus (introduced in version 6.14), users gain access to additional tools like Tosca Structure, Tosca Fluid, fe-safe, and Isight without requiring separate licenses. Key benefits include:
  • Unified access to all solution technologies.
  • Increased efficiency by utilizing a single token pool.
  • Simplified purchase and management process.
  • Enhanced value from simulation investments by leveraging the entire portfolio.

Firstly, contact a licensed Abaqus vendor to discuss your needs:

• Explain your project requirements and get guidance on the appropriate Abaqus software package(s).
• Inquire about licensing options, pricing, and any available support or training services.

Purchase Abaqus software:

• Work with the vendor to purchase the necessary Abaqus licenses.
• Receive instructions on how to download and install the Abaqus software.

Set up your Abaqus environment:

• Install the Abaqus software on your computer or in a high-performance computing environment, following the vendor’s installation guide.
• Ensure you have the necessary hardware and system requirements to run Abaqus effectively.
• Configure any required software integrations, such as with your CAD system (e.g., CATIA, SOLIDWORKS) using the Abaqus associative interfaces.

To install Abaqus subroutines, you can follow these steps:

1. Download and install Microsoft Visual Studio 2010 Professional (Community, Professional, or Enterprise editions are acceptable, but not the Express edition). Visual Studio acts as the linker, connecting your compiled code with the necessary libraries for the Abaqus solver.
2. Download and install Intel® Parallel Studio XE Composer Edition for Fortran and C++ Windows. This compiler translates your text subroutine into machine code that the computer can understand.
3. Ensure that the correct version of msmpi is installed on your computer. This version is typically provided with your Abaqus installation media and must match the version of Abaqus you are using. If the wrong version is installed, you will encounter a linking error.
4. Before launching your simulation with user subroutines, set the correct environmental variables for your compiler and linker. This can be done by editing the “Abaqus command” shortcut for command line execution or the “Abaqus/CAE” shortcut for use within the CAE environment. The exact commands will depend on your system configuration and the installation paths of the software.

By following these steps, you should be able to successfully install and use Abaqus subroutines for your simulations. Feel free to get in touch if you run into any roadblocks.

Abaqus/CAE offers a comprehensive suite of tools for post-processing finite element analysis results. These tools are designed to help users visualize and interpret the outcomes of their simulations effectively. The key post-processing features in Abaqus/CAE include:

• Users can manipulate the display of different variables, such as stress, strain, and displacement, to better understand the results of their analysis.
• Abaqus/CAE allows for the creation of contour plots, which can display variable distributions across the model. Users have the option to control how Abaqus/CAE computes contour limits, including auto-computed limits and manual adjustments to focus on areas of interest.
• The software can plot graphs to show the evolution of a variable throughout the analysis. This feature is particularly useful for tracking changes over time or across different model sections.
• Abaqus/CAE provides options to control display lists through the graphics options dialog box, enhancing the visualization of results by adjusting hardware and software rendering settings.
• Users can customize the appearance of contour plots, including the selection of variables to display, adjusting the contour limits, and choosing between different plot types (e.g., quilt, line, or banded contours).
• Abaqus/CAE supports various methods for result visualization, including deformed shape plots and symbol plots, allowing users to gain insights into the physical behavior of their models under different conditions.
• The software enables the selection of primary field output variables for detailed analysis. Users can control the variable, invariant, or component displayed in contour plots, model probing, and view cuts based on an isosurface.
• Abaqus/CAE includes a post-processing calculator that performs calculations on data written to the output database, such as extrapolation of integration point quantities to nodes or interpolation to the centroid of an element.
• Users have the ability to adjust common plot options, such as deformation scale, and customize contour plots to highlight specific aspects of the analysis results.

These tools are integral to the post-processing phase in Abaqus/CAE, enabling users to extract meaningful insights from their simulation data, optimize their models, and make informed decisions based on the analysis results.

To create a new part in Abaqus/CAE, follow these steps:

• Launch Abaqus CAE.
• Choose the type of analysis for your model, typically standard or explicit, from the model database.
• Click on the ‘create part’ icon in the CAE window.
• In the dialog box that appears, enter the name of the part, select the type of part (solid, shell, etc.), and set the ‘approximate size’, which determines the size of the sketcher grid.
• Use the Abaqus sketcher, which provides geometry-based tools on the left, to sketch your part in the main window, similar to other CAD utilities.
• After sketching the geometry, you can add additional details or features at the bottom of the sketcher window.
• Press the middle mouse button to confirm the geometry you’ve created. Exit the sketcher by pressing ‘DONE’ or the middle mouse button again.
• Follow any additional prompts to finalize the creation of the part, such as defining extrusion depth if the part is an extrusion.
• The newly created part will appear in the model tree on the left side of the screen, with all its features, and the solid representation will be visible in the main design window.

Remember to save your work regularly, as Abaqus CAE does not automatically save your model database. For more detailed instructions on using the sketcher tools, you can refer to the Abaqus CAE user’s manual.

To create a multipurpose macro in Abaqus, which can automate repetitive tasks or vary parameters for optimization studies, follow these steps:

• Go to `file > macro manager` in Abaqus/CAE to open the macro manager window.
• Click on `create` to start recording the macro. Choose a name for your macro and decide where to save it. You can save it in the default `mome` directory or set a custom `work` directory.
• Execute the sequence of actions you want to automate. This can include creating geometry, defining steps, applying loads, setting boundary conditions, and more. Every action you take will be recorded.
• Once you have completed the desired actions, click on `stop recording`. The actions are now saved as a Python script.
• Access the recorded macro from the macro manager window whenever you need to perform the recorded sequence of actions.
• For more advanced customization, you can open the `abaqusMacros.py` file to copy, modify, or further develop your Python code. This allows you to tailor the macro for various purposes and make it multipurpose.

Remember, macros are powerful tools in Abaqus that save time and enhance productivity by automating complex or repetitive tasks. With the macro manager, even users with limited scripting experience can create effective macros for a wide range of applications.

To set up an Abaqus High-Performance Computing (HPC) cluster, follow these steps:

• Begin with a Beowulf cluster configuration, which typically includes one master node and multiple slave nodes. For a budget setup, you can use outdated dual-core machines, a monitor switcher, and a network switch.
• Choose Linux as the operating system for cost efficiency. Ensure that the master node can access the slaves, typically via SSH remote login. No additional prerequisites are needed before installing Abaqus, as it handles file sharing and MPI processes internally.
• Install Abaqus on the master node and all slave nodes. Abaqus comes with its own MPI (message passing interface) library, so you do not need to use the open-source version. The MPI library is essential for parallel processing and must be installed as part of the Abaqus API on every node.
• To run Abaqus on the cluster, submit a job with more cores than the master has locally. This will distribute the computational load across the slave nodes.
• Edit the environment file on the master node to specify which computers Abaqus can use and the number of cores available on each. This step is crucial for Abaqus to recognize the cluster configuration.

Remember, while building an HPC cluster on a budget is possible, the performance may be limited by the hardware capabilities. The complexity of setting up the cluster depends on your willingness to research and experiment with the software. Running Abaqus on a cluster is straightforward once the environment is correctly configured. Always check the system requirements for the specific version of Abaqus you are using to ensure compatibility.

General contact provides a streamlined and automated approach to defining interactions between surfaces in a model. Unlike traditional contact pairs, which require manual specification of individual interacting surfaces, General contact assumes that any surface can interact with any other surface within the defined contact domain. This makes it particularly useful for complex models with multiple potential contact interactions.

Key features of general contact include:

• Automatic identification and management of various contact types, such as surface-to-surface, edge-to-surface, and edge-to-edge interactions, reducing setup time significantly.
• Applicable to both rigid and deformable bodies, it is ideal for large assemblies or simulations requiring comprehensive contact detection.
• The all-inclusive contact domain simplifies the setup process by considering all external surfaces by default. Users can refine this by including or excluding specific surfaces to optimize performance.

Solver compatibility:

• In Abaqus/Standard, general contact is defined only in the initial step and remains active throughout the analysis.
• In Abaqus/Explicit, it can be applied at any step, offering more flexibility.
• While general contact simplifies the process, it may increase computational effort due to broader contact definitions. For models requiring precise control over specific interactions, traditional contact pairs may still be preferred. However, for most simulations, SIMULIA recommends using general contact due to its efficiency and adaptability.

Mesh sensitivity analysis in Abaqus evaluates how the results of an FEA (finite element analysis) change with varying mesh densities. It ensures that the numerical solution converges to an accurate and reliable result as the mesh is refined. This process is critical for achieving dependable simulations without unnecessary computational costs.

In FEA, the solution tends to converge to a unique value as the mesh density increases. A “converged mesh” is one where further refinement produces negligible changes in results, such as stresses, displacements, or energy values.

For example, in a CEL (coupled Eulerian-Lagrangian) study involving a ball-water interaction, different mesh densities produced varying outcomes, such as the number of bounces or whether the ball was submerged. This highlights how mesh density can drastically affect results in dynamic simulations.

While finer meshes improve accuracy, they also increase computation time and resource usage. A balance must be struck between mesh density and computational efficiency by focusing refinement on critical regions (e.g., areas with high stress gradients).

Mesh dependency in CEL studies

In CEL analyses, such as impact or fluid-structure interaction problems, mesh dependency can influence energy dissipation and deformation patterns. Refining the mesh improves convergence, but may also alter physical behaviors observed in simulations.

Practical recommendations

• Perform a mesh convergence study by running simulations with progressively finer meshes until results stabilize.
• Use coarse meshes for trend analysis, but rely on refined meshes for accurate magnitudes of stress or displacement.
• Apply local refinement in regions of interest (e.g., stress concentrations) while keeping coarser meshes elsewhere to optimize performance.

Node-to-surface contact is a common interaction setup in Abaqus, but improper configurations can lead to issues such as unrealistic stress concentrations or master nodes passing through the slave surface. To ensure accurate and stable results, follow these key considerations:

• Master-slave surface setup
  • Slave surface: Assign the slave surface to the smaller and softer body with higher element density. This ensures that the slave surface conforms better to the master surface.
  • Master surface: Allocate the master surface to the stiffer body (considering both geometry and material properties) and ensure it has a coarser mesh compared to the slave surface.
• Element density
  • The element density of the slave surface should always be higher than that of the master surface. This minimizes issues such as master nodes passing through the slave surface or stress singularities at contact points.
• Geometry and material properties
  • Prioritize assigning the slave surface to the smaller body, as this reduces computational errors and improves contact behavior.
  • If it is not possible to meet all criteria, prioritize mesh density and size over material stiffness when defining master-slave relationships.
• Common pitfalls
  • Master nodes passing through slave surface: This occurs when the master surface has a finer mesh or is assigned to a smaller body. It can lead to unrealistic results.
  • Stress singularities: Concentrated stresses may appear if there are too few interacting nodes due to a coarse slave mesh or improper setup.
• Best practices
  • Refine the mesh on the master surface appropriately if contact stresses are of interest.
  • Use frictionless “hard contact” interactions for simpler setups unless frictional behavior is critical.
  • Conduct sensitivity studies to validate that your setup produces stable and realistic results.

Surface-to-surface contact in Abaqus is a discretization method that enhances the accuracy and stability of contact simulations by better enforcing contact constraints across interacting surfaces. Unlike node-to-surface contact, it uses the average positions of slave nodes to calculate constraints, reducing issues like stress irregularities and unrealistic penetration. Key considerations for surface-to-surface contact include:

Master-slave relationship

• Ideally, the slave surface should belong to the smaller, softer body with higher element density.
• The master surface should be assigned to the stiffer body with a coarser mesh. This setup ensures accurate stress distribution and avoids issues like master nodes passing through the slave surface.

Mesh density

• A finer mesh on the slave surface improves accuracy by better capturing stress gradients and ensuring proper constraint enforcement.
• Coarse slave meshes can lead to longer processing times and inaccurate results, as seen in cases where edge loads are not properly captured.

Stress distribution

• Surface-to-surface contact reduces stress artifacts compared to node-to-surface methods. However, high-stress regions (e.g., edge loads) are still influenced by the master-slave relationship and mesh quality.

Efficiency

• While surface-to-surface contact is more robust than node-to-surface contact, adhering to correct master-slave assignments further improves computational efficiency and result reliability.

Best practices

• Use surface-to-surface contact over node-to-surface whenever possible for more accurate results.
• Prioritize assigning the slave surface to the smaller body with higher mesh density if all criteria cannot be met.
• Perform sensitivity analyses to validate that your mesh density and master-slave definitions yield stable results.

Second-order elements, such as C3D20R, can present unique challenges in contact analysis due to their behavior in certain discretization methods. Here are the key considerations:

1. Discretization method matters:
   • When using second-order elements, the choice between node-to-surface and surface-to-surface discretization significantly impacts results. For example, node-to-surface contacts may introduce additional mid-face nodes (e.g., converting C3D20R to C3D27R), which can alter nodal force distributions and increase computational complexity.
2. Force distribution behavior:
   • Second-order elements can produce tessellated or irregular force distributions (e.g., CNORMF values) when subjected to uniform pressure. This is due to the way nodal forces are calculated, especially in the absence of mid-face nodes.
3. Performance and accuracy:
   • First-order elements (e.g., C3D8I) are often preferred for contact regions as they simplify calculations, reduce solve time, and improve accuracy for nodal force outputs. If second-order elements are necessary, using surface-to-surface discretization is recommended to avoid additional mid-face nodes.
4. Model requirements:
   • The suitability of second-order elements depends on your specific model and output needs. If precise nodal force values are not critical, the irregularities in force distribution may not significantly affect other outputs like stress or pressure.
5. For optimal results:
   • Use first-order elements for slave surfaces in contact.
   • Opt for surface-to-surface discretization when second-order elements are unavoidable.
   • Evaluate whether the CNORMF behavior impacts your analysis goals.

The Hashin damage model in Abaqus is a widely used failure theory designed to predict damage initiation and evolution in fiber-reinforced composite materials. It provides a detailed breakdown of failure mechanisms by distinguishing between fiber and matrix failures under different loading conditions. This makes it particularly suitable for accurately simulating the complex behavior of composites.

Key Features of the Hashin Damage Model:

1. Damage initiation criteria:
   Based on Hashin’s theory, the model identifies four primary failure modes:
   • HSNFTCRT (fiber tension): rupture of fibers under tensile stress.
   • HSNFCCRT (fiber compression): Buckling or kinking of fibers under compressive stress.
   • HSNMTCRT (matrix tension): cracking in the matrix due to transverse tensile stress and shear.
   • HSNMCCRT (matrix compression): crushing of the matrix under transverse compressive stress and shear.
   • These criteria are implemented using plane stress elements like shell, continuum shell, and membrane elements. For 3D solid elements, alternative models like LaRC05 or custom VUMAT subroutines are required.
2. Damage evolution:
   • After damage initiation, Abaqus uses an energy-based approach to model progressive material degradation. The fracture energy (Gf) for each failure mode governs the rate at which stiffness is reduced, ensuring realistic simulation of post-damage behavior.
3. Element deletion:
   • Abaqus allows for element removal once all material points within an element are fully degraded, simulating complete material failure. This feature is particularly useful for analyzing large-scale failures like delamination or bolt-bearing damage in composite joints.
4. Applications in composite analysis:
   • The Hashin damage model is commonly used to simulate ply-level failures in laminated composites, such as CFRPs (carbon fiber-reinforced polymers). It can predict localized damage near stress concentrations (e.g., bolt holes) and assess overall structural integrity under complex loading conditions.
   • In bolted composite joints, it enables accurate modeling of interlaminar stresses and ply failures, providing insights into factors like clamping force effects and joint strength degradation.
5. Limitations and recommendations:
   • The Hashin model is limited to plane stress formulations and cannot directly handle 3D stress states. For applications requiring through-thickness stress analysis (e.g., pressure vessels), users should consider LaRC05 or custom subroutines like VUMAT.
   • Accurate results require detailed input parameters, including tensile/compressive strengths and shear properties for both fibers and the matrix. A mesh convergence study is also recommended to ensure reliability.