Using Viscoelastic and Path-Dependent Models for Analyzing the Curing Process in Fiber-Reinforced Composites With Abaqus subroutines

 290.0
(2)
Fiber-reinforced composites, widely used across various industries, consist of reinforcing fibers embedded in a matrix. During the curing process, this mixture transforms into a stable material. Curing is a critical step to ensure the durability and strength of the final product. In one of our intermediate packages, we used Abaqus to analyze the curing process in composites with linear elastic models. While these models are straightforward and user-friendly, their accuracy is limited because composites exhibit viscoelastic behavior during curing, rather than elastic behavior. To address this limitation, the current package introduces two more advanced and accurate models for analyzing residual stresses in composites: the viscoelastic model and the path-dependent model. These models offer significantly greater accuracy compared to linear elastic ones but involve added complexity. To simplify this complexity for users, the package begins with a comprehensive overview of the underlying theories and formulations for the viscoelastic and path-dependent models. It then provides detailed guidance on implementing these models using Abaqus subroutines. Finally, workshops are included to demonstrate how the viscoelastic model significantly improves the prediction of residual stresses in composites compared to the elastic models featured in our intermediate package.

Pultrusion Crack Simulation in Large-Size Profiles | Pultrusion Abaqus

 250.0

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 material property changes, and optimization strategies for enhancing manufacturing efficiency and product quality. This research provides practical knowledge for implementing findings in real-world applications, advancing composite material production.

Notice that, pultrusion is a composite curing method, which may share some overlapping features with our Intermediate and Advanced curing packages. However, what sets pultrusion apart is that the composite passes over a heated die during the process. In this project, the die has also been modeled, with environmental heat applied to it using convection and a film subroutine. The heat is subsequently transferred to the sample through contact with the die. Afterward the die is removed. All these procedure is modeled in this project, with Abaqus CAE step-by-step. In contrast, in our Intermediate and Advanced packages for the oven curing of prepregs, no die has been modeled. The heat is applied without convection and, for simplicity, the heat is treated as a first-type boundary condition, which introduces some errors.

UEXPAN and VUEXPAN Subroutine

 120.0

In this tutorial, how to define increments of thermal strains, in order to model thermal expansion, is taught. The implementation of thermal expansion in model is done with UEXPAN and VUEXPAN subroutines for Abaqus/Standard solver (implicit method). In user subroutines UEXPAN or VUEXPAN, the increments of thermal strains can be defined as functions of predefined field variables, temperature, and state variables.

UEXPAN and VUEXPAN are called for all integration points of part elements where the definition of material or gasket behavior includes user-subroutine-defined thermal expansion.

The subroutines are used when the material’s thermal expansion behavior is too complex to model with the "EXPANSION" option in the Abaqus software environment. For example, the subroutines are used in problems where the thermal strains are complexly dependent on temperature, predefined field variables, and state variables, and there is a need to update these variables.

The user subroutine UEXPAN is called twice per element point in each iteration during coupled thermal-electrical-structural or coupled temperature-displacement analyses.