Introduction: User-defined element
Abaqus user element (UEL) subroutine (user-defined element) is the most difficult, yet the most versatile and flexible subroutine offered by Abaqus to its user. Compared to most other subroutines, this requires an understanding of the theory, element formulation, and a significant amount of programming by the user. This painstaking process of developing UEL is useful in multiple cases when Abaqus does not offer a built-in element. Some examples of when UEL subroutines can be used in Abaqus are: Abaqus user element tutorial
- Implementing B-bar (small strain) or F-bar (large strain) element formulation for nearly incompressible materials. There are some other advanced mixed or hybrid finite element models for nearly incompressible materials that are implemented using UEL.
- Perform isogeometric analysis using different shape functions and integration schemes.
- Phase field or gradient damage model for ductile and brittle fracture of different types of materials,
- Coupled chemo-mechanical model for hydrogels or biological tissues or electro-mechanical model dielectric elastomers, and any other coupled multi-field models for materials.
When an Abaqus model is built with user elements instead of the standard elements offered by Abaqus, Abaqus solvers call this subroutine for each element. The user needs to program the tangent or stiffness matrix and the residual forces for each element. Optionally, the user can program a custom time-stepping algorithm and store the state variables for time-dependent and path-dependent behavior. Similar to the UMAT subroutine in Abaqus, users can also define different constitutive models within the UEL.
This tutorial will teach the user how to develop a standard continuum finite element model and how to implement that model using Fortran in a general-purpose manner within the Abaqus. Additionally, it will discuss in detail how to build and modify an Abaqus model and post-process the results in Abaqus/CAE for UEL. However, since this tutorial requires a substantial amount of programming in Fortran, users are suggested to review the resources on Fortran programming on the official website and our website as well.
UEL element stiffness matrix
The first lesson will go over the finite element formulation and constitutive model that we will program in the UEL subroutine of this tutorial. In this lesson, we chose isotropic linear elastic material as an example. However, it can be easily extended to different material behaviors such as viscoelasticity and elasto-plasticity. The lesson will start with the small strain kinematics and isotropic linear elastic material behavior, and then discuss the strong form, weak form, and discretized form of the governing equations. This lesson will highlight the UEL element stiffness matrix and element residual vector which are to be programmed in the first workshop. This lesson will also cover shape functions and numerical integration and finally, we will conclude this lesson with pseudocode for the UEL to be programmed in the workshop.
UEL inputs and outputs
The second lesson will provide a brief overview of the UEL subroutine and how they are executed in Abaqus. This lesson will then go over the UEL input and output arguments and explain their role in developing the subroutine. In the main program, we also use the UVARM subroutine for post-processing the results for the user element. We will go over the structure of this subroutine as well. We will follow the information from Abaqus documentation.
Citlali –
Using this package has been straightforward and effective. I’m completely satisfied and impressed by its performance! The detailed training and practical examples made the learning process very smooth.
Itzel –
I recently purchased the Abaqus User Element Tutorial package, and I couldn’t be more satisfied! This comprehensive course is perfect for anyone looking to dive deep into user-defined elements (UEL) in Abaqus. The content is well-structured, making complex concepts easy to understand.
The tutorial covers everything from the basics of UEL to advanced applications, including the formulation of different element types and integration schemes. The step-by-step instructions and practical examples significantly enhanced my learning experience. I especially appreciated the detailed explanations of the UEL element stiffness matrix and the residual vector.
The included video tutorials are a fantastic resource, providing clear visual guidance that complements the written material. Plus, the package comes with all the necessary files, making it easy to follow along and implement what you learn.
Overall, this package is a must-have for anyone serious about mastering UEL in Abaqus. The support and resources provided are top-notch, and I feel much more confident in my ability to create custom elements now. Highly recommend it to both beginners and advanced users!
Iker –
Your package has truly transformed my workflow. I especially benefited from the step-by-step instructions and practical examples, which significantly increased my productivity. The clear and detailed information provided is invaluable.
Ciro –
My experience with the Abaqus User Element Tutorial package has been exceptionally positive! The video tutorials and instructional content greatly assisted me in understanding how to work with custom elements. I’m really pleased with the quality of the results I achieved. Can you offer guidance on troubleshooting common issues? Additionally, do you have any documentation for optimizing the use of this package?
Ximena –
Working with your package has been a fantastic experience. I’m really pleased with its efficiency and simplicity! This package has enabled me to work much more effectively on my projects. The explanations on using custom elements and example codes have been tremendously helpful. Can you provide any advice for next steps? Are there guides available for utilizing more advanced features?
Renato –
This package has made my work considerably easier. I am very satisfied with its quality and performance. The access to practical examples on custom elements has been incredibly helpful. Can you tell me if there are any new updates available for this package and what new features may be added?
Nayeli –
I am very happy with your package and would recommend it to my friends. This package has genuinely helped me achieve better results in my work. The customization capabilities of the elements are one of the standout features that I truly enjoyed. Any new features on the horizon that I could access?
Tadeo –
I recently used the Abaqus User Element Tutorial package, and I was truly amazed by the results! The comprehensive explanations on how to create custom elements helped me achieve my goals faster than I anticipated. I’m extremely satisfied with the quality and functionality of this package. Can you provide more information about its advanced features? Are there any resources or specific guidelines that I can refer to for improving my usage of this package?
Yaretzi –
Your package has significantly increased my productivity, and I am fully satisfied with the results! I was able to handle complex tasks with ease using the provided tools. I particularly appreciate the quality of the training materials and practical examples.
Dante –
I am really impressed with this package! It was easy to use and incredibly effective, yielding highly satisfactory results. One of the best features is the ability to customize elements, which allowed me to easily address the specific needs of my project.