Session: 01-06-01: Impact, Fatigue, Damage and Fracture of Composite Structures

Paper Number: 125324

125324 - A Parametric Study for Low-Velocity Impact Modeling of Fiber-Reinforced Composites Using Shell Elements: Guidelines for Finite Element Analysis 

Fiber-reinforced composites have become the major material choice for various industries, ranging from the aerospace and wind industry to boats and the automotive industry. The widespread use of fiber-reinforced composites is mainly attributed to their exceptional specific in-plane mechanical properties, making them suitable for applications where lightweight yet high strength and stiffness properties are crucial. Despite their advantages, composites are susceptible to damages from transverse impact load. Impact load on composite laminates can induce a range of damages, from barely visible damages to several complex damage mechanisms interacting simultaneously, compromising the composite's structural integrity and performance. Therefore, assessing the impact behavior of composite laminates subjected to transverse impact load is essential. The finite element method (FEM) is a powerful tool for this purpose, which allows for detailed and accurate analysis of impact events on composites. Despite FEM's accuracy, it demands extensive computational resources. In this context, shell elements have been widely used for impact modeling on composites, offering reasonable accuracy with less computational intensity compared to solid elements. However, there is a noticeable gap in the literature regarding a benchmark study on the best practices and highlighting clear limitations when using shell elements for impact modeling on composite laminates. In addition, the applicability of shell elements on the impact modeling of thick composite laminates (thickness-to-length ratio greater than 1/15) has remained unanswered. Hence, this study aims to (1) provide a comprehensive modeling guideline for the low-velocity impact (LVI) of composite laminates using shell elements, (2) evaluate the accuracy of shell elements in predicting the impact response (contact force, displacement, and energy history) and impact-induced damage size on composite laminates, and (3) determine the thickness limit at which the shell elements can be used effectively for LVI of composite laminates. For this purpose, we use the conventional shell elements (S4 and S4R) and the Abaqus/Explicit solver in the commercial code, Abaqus. Furthermore, Hashin's failure criterion and Abaqus' continuum damage model are used for damage initiation and evolution, respectively. A parametric study is considered that analyzes the effect of - (a) projectile modeling technique, (b) the projectile's mesh size and mesh control, (c) the contact algorithm, (d) the hourglass control algorithms in Abaqus, (e) full (S4) and reduced (S4R) element formulation, and (f) the number of the through-the-thickness integration points - on the impact response of composite laminates. All the finite element models in this study undergo a mesh convergence study, and the results are compared to the analytical, numerical, and experimental results in the literature. This study is the first attempt to establish a benchmark for the finite element modeling of LVI on composite laminates using shell elements. The findings contribute to more accurate finite element analysis and provide insight into the appropriate thickness range for the application of the conventional shell elements in LVI.

Presenting Author: Amir Baharvand University of Maine

Presenting Author Biography: Amir is a Ph.D. student at the Department of Mechanical Engineering, University of Maine, US. He received his Bachelor's degree in Mechanical Engineering-Manufacturing from Azad University, Iran. Later, he obtained his Master's degree in Aerospace Engineering from Delft University of Technology, the Netherlands, and Wind Engineering from Technical University of Denmark, Denmark. His research includes damage tolerance of composite structures, fiber hybridization, and numerical modeling of composite structures.