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Abaqus Kelvin Voigt Viscoelastic Simulation Using UMAT and VUMAT Subroutines

A viscoelastic material exhibits characteristics of both solids and fluids when subjected to stress. This distinct behavior makes them useful in various applications. To use viscoelastic materials in various applications, we need to predict their behavior under different loading conditions. This tutorial discusses in detail how numerical methods address this matter (Abaqus kelvin voigt viscoelastic). The Kelvin-Voigt model describes viscoelastic behavior using a spring and a damper in parallel (kelvin voigt model abaqus). It effectively predicts creep, simulates material responses to impacts, and determines viscoelastic properties of materials like foams, rubbers, and biological tissues. Despite its strengths, it has limitations in describing stress relaxation. This tutorial focuses on implementing the Kelvin-Voigt model in Abaqus CAE using UMAT and VUMAT subroutines. While these subroutines are powerful, they require Fortran knowledge, posing a challenge. To assist, the tutorial provides a step-by-step guide on reviewing the model's formulation and writing the subroutines for both standard and explicit solvers. The tutorial demonstrates capturing damage in a problem, but the results are general, such as stress and displacement. You can customize the subroutine for your models and extract specific results without significant difficulty.

Viscoplasticity Abaqus Simulation Using UMAT Subroutine | Perzyna Viscoplastic Model


Viscoplasticity describes the rate-dependent inelastic behavior of materials, where deformation depends on both stress magnitude and application speed. This concept is crucial in many engineering applications, such as designing structures under dynamic loads, modeling soil behavior during earthquakes, and developing materials with specific mechanical properties. Viscoplasticity Abaqus simulation, especially using Abaqus with UMAT subroutines, are vital for understanding, predicting, and optimizing the behavior of viscoplastic materials. This tutorial focuses on implementing the Perzyna viscoplasticity model in Abaqus. The Perzyna viscoplastic model, a strain rate-dependent viscoplasticity model, relates stress to strain through specific constitutive relations. This involves defining plastic strain rate based on stress state, internal variables, and relaxation time. The tutorial provides general UMAT codes for viscoplastic analysis, yielding results like stress fields essential for various engineering applications. These simulations help in predicting permanent deformations, assessing structural failure points, and analyzing stability under different loads, benefiting fields such as aerospace, automotive, civil engineering, and energy.

Pultrusion Crack Simulation in Large-Size Profiles | Pultrusion Abaqus


Pultrusion is a crucial task for producing constant-profile composites by pulling fibers through a resin bath and heated die. Simulations play a vital role in optimizing parameters like pulling speed and die temperature to enhance product quality and efficiency. They predict material property changes and aid in process control, reducing reliance on extensive experimental trials. However, simulations face challenges such as accurately modeling complex material behaviors and requiring significant computational resources. These challenges underscore the need for precise simulation methods to improve Pultrusion processes. This study employs ABAQUS with user subroutines for detailed mechanical behavior simulations, including curing kinetics and resin properties. Key findings include insights into crack formation (pultrusion crack simulation), material property changes, and optimization strategies for enhancing manufacturing efficiency and product quality. This research (pultrusion Abaqus) provides practical knowledge for implementing findings in real-world applications, advancing composite material production.

Elastomeric Foam Simulation Using Abaqus Subroutines

This study focuses on modeling the mechanical behavior of open-cell, isotropic elastomeric foams. It is essential for applications in materials science and engineering. The project offers insights into designing customized elastomeric foam materials tailored for impact protection in automotive, sports equipment, and aerospace industries. Numerical simulations, using software like Abaqus, enable the prediction of complex behaviors such as hyperelasticity and viscoelasticity under various loading conditions. This finite element analysis of elastomers includes theoretical formulations for hyperelastic constitutive models based on logarithmic strain invariants, crucial for accurately describing large deformations. Practical benefits include the implementation of user-material subroutines in Abaqus, facilitating future extensions to incorporate strain-rate sensitivity, and microstructural defects analysis. This comprehensive approach equips learners with theoretical knowledge and practical tools to advance elastomeric foam simulation. Moreover, it enhances their capability to innovate and optimize materials for diverse applications.

Abaqus convergence tutorial | Introduction to Nonlinearity and Convergence in ABAQUS


This package introduces nonlinear problems and convergence issues in Abaqus. Solution convergence in Abaqus refers to the process of refining the numerical solution until it reaches a stable and accurate state. Convergence is of great importance especially when your problem is nonlinear; So, the analyst must know the different sources of nonlinearity and then can decide how to handle the nonlinearity to make solution convergence. Sometimes the linear approximation can be useful, otherwise implementing the different numerical techniques may lead to convergence.

Through this tutorial, different nonlinearity sources are introduced and the difference between linear and nonlinear problems is discussed. With this knowledge, you can decide whether you can use linear approximation for your nonlinear problem or not. Moreover, you will understand the different numerical techniques which are used to solve nonlinear problems such as Newton-Raphson.

All of the theories in this package are implemented in two practical workshops. These workshops include modeling nonlinear behavior in Abaqus and its convergence study and checking different numerical techniques convergence behavior using both as-built material in Abaqus/CAE and UMAT subroutine.