Understanding And Predicting The Stress Relaxation Behavior Of Short Fiber Composites
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Author | : Numaira Obaid |
Publisher | : |
Total Pages | : |
Release | : 2018 |
Genre | : |
ISBN | : |
Download Understanding and Predicting the Stress Relaxation Behavior of Short-Fiber Composites Book in PDF, Epub and Kindle
The viscoelastic properties of short-fiber composites are complex and not well-understood. Previous experimental work has shown that the viscoelastic properties of short-fiber composites are affected by both elastic fibers and the matrix, which is baffling since elastic fibers do not exhibit any time-dependence of their own. The goal of this study was to understand why and how elastic fibers can alter time-dependent behavior when contained in a composite. In this thesis, conventional shear-lag theory was adapted to include a time-dependent matrix and a novel analytical model was used to predict the tensile relaxation modulus of short-fiber composites. The model highlighted the importance of incorporating both the time-dependent tensile modulus of the matrix as well as its time-dependent shear modulus. Investigations using the model showed that since stress transfer in a short-fiber composite occurs through interfacial shearing, the time-dependent shear modulus of the matrix results in time-varying stress transfer the fiber. Since the stress in the fiber is time-dependent, it exhibits an apparent stress relaxation stemming from the relaxing shear modulus of the matrix. The model predictions were validated using finite-element simulations and experimental data. Comparison to real data confirmed the hypothesis that the time-dependency observed in elastic fibers stemmed from the indirect time-dependency imposed by the time-varying stress transfer from the matrix. The model was also used to determine the effect of various parameters including fiber aspect ratio and fiber volume fraction. For the first time, a critical aspect ratio for viscoelasticity was introduced. This was defined as the aspect ratio at which the contribution to composite stress relaxation by the fiber is maximized. The effect of fiber orientation was also examined, and an analytical model was developed to predict the stress relaxation of composites containing randomly-oriented fibers. It was found that random orientation in the plane would shrink the effect of fibers by one-third of what would be observed in oriented composites. In the last part of the thesis, we investigated the strain rate-dependence of short fiber-reinforced foams. The study highlighted a potential area where knowledge of the stress relaxation behavior of the short-fiber composites could prove useful.
Author | : Sabu Thomas |
Publisher | : Elsevier |
Total Pages | : 596 |
Release | : 2024-01-16 |
Genre | : Technology & Engineering |
ISBN | : 044318609X |
Download Elastomeric Nanocellulose Composites Book in PDF, Epub and Kindle
Elastomeric Nanocellulose Composites provides an in-depth study of recent developments in this fast-evolving research field. This book covers diverse aspects of materials engineering, surface treatments, and fabrication of green nanocomposites. It consolidates recent studies and qualitative findings on the incorporation of a myriad of nanocellulose variants into various types of elastomer matrices with the main goal of enhancing its mechanical integrity and potentially phasing out conventional elastomer fillers. The current market is likewise discussed in detail. This book will provide an in-depth study of current developments of nanocellulose incorporated elastomer composites and their applications. The book will be an essential reference resource for material scientists, academic and industrial researchers, and technologists covering all aspects in the field. Carbon black and silica are currently used as fillers in elastomer-based composites, but the use of these reinforcing agents is not sustainable or eco-friendly. Therefore there is a need to look for more sustainable filler materials for elastomers. Assists readers in solving fundamental and application-related problems in the development of nanocellulose filled elastomers Discusses characterization techniques used for analyzing elastomer nanocomposites Provides various attributes of nanocellulose, its composites with different types of elastomeric materials (both natural and synthetic) and its potential for advanced applications Includes comprehensive, well structured content to maintain consistency and flow to help readers easily navigate chapters
Author | : Rony Das |
Publisher | : |
Total Pages | : 82 |
Release | : 2012 |
Genre | : Electronic dissertations |
ISBN | : |
Download Stress Relaxation Behavior of Carbon Fiber-epoxy Prepreg Composites During and After Cure Book in PDF, Epub and Kindle
This study presents the experimental results of time-temperature dependent viscoelastic behavior and cure kinetics of two commercial carbon fiber/epoxy prepregs, IM7/977-2 unidirectional tape (UD) and IM7/977-2 plain weave fabric (PW). An in-depth study on the oscillatory and transient rheological behavior of prepreg composites is conducted using a dynamic mechanical analyzer (DMA) and the study of cure kinetics is conducted using a differential scanning calorimeter (DSC). A novel experimental methodology is proposed in this study to describe the stress relaxation behavior of prepreg composites during cure. Time- and cure-dependent stress relaxation behavior of prepreg composites is studied in three in-plane directions: 0, 45, and 90 degrees of the laminates. Several other factors, such as the mismatch of fiber orientation of adjoining plies, stacking sequence of the laminate, and relative position of the plies with respect to the neutral axis are considered to study their effects on the stress relaxation behavior during cure. The stress relaxation behavior of cured composites is obtained by utilizing the time-temperature superposition (TTS) principle. TTS study on UD laminates (in 0, 45, and 90 degree fiber directions) is conducted at four distinct cure states, whereas the PW laminate is studied in the same fiber directions but at a fully cured state only. Experimental results are used to predict the life cycle of the composite products by generating the stress relaxation master curves for different combinations of fiber orientation and cure states. The study shows that the relaxation modulus during cure is case dependent, which leads to the assumption that the relaxation of process-induced stresses during cure varies for different conditions. Moreover, when comparing the performance of UD and PW prepregs, it shows that the PW laminate relaxes more residual stress than the UD laminate during cure. At cured condition, the PW material shows better long-term mechanical performance than UD material.
Author | : Akarsh Verma |
Publisher | : Elsevier |
Total Pages | : 557 |
Release | : 2024-01-19 |
Genre | : Technology & Engineering |
ISBN | : 0443190100 |
Download Dynamic Mechanical and Creep-Recovery Behavior of Polymer-Based Composites Book in PDF, Epub and Kindle
Dynamic Mechanical and Creep-Recovery Behaviour of Polymer-Based Composites: Mechanical and Mathematical Modeling covers mathematical modelling, dynamic mechanical analysis, and the ways in which various factors impact the creep-recovery behaviour of polymer composites. The effects of polymer molecular weight, plasticizers, cross-linking agents, and chemical treatment of filler material are addressed and information on thermoplastic and thermosetting polymer-based composites is also covered, including their various applications and the advantages and disadvantages of their use in different settings. The final 2 chapters of the book cover mathematical modeling of creep-recovery behavior for polymer composites and software-based simulation of creep-recovery in polymer composites, respectively. Dynamic Mechanical and Creep-Recovery Behaviour of Polymer-Based Composites: Mechanical and Mathematical Modeling covers mathematical modelling, dynamic mechanical analysis, and the ways in which various factors impact the creep-recovery behaviour of polymer composites. The effects of polymer molecular weight, plasticizers, cross-linking agents, and chemical treatment of filler material are addressed and information on thermoplastic and thermosetting polymer-based composites is also covered, including their various applications and the advantages and disadvantages of their use in different settings. The final 2 chapters of the book cover mathematical modeling of creep-recovery behavior for polymer composites and software-based simulation of creep-recovery in polymer composites, respectively. Analyzes the dynamic mechanical and creep-recovery behaviors of thermoplastic and thermosetting polymer composites in a variety of applications Features diverse mechanical/mathematical models utilized to fit data collected from creep-recovery studies Covers various factors that influence dynamic mechanical properties Discusses the advantages and disadvantages of using these materials in different settings
Author | : University of Delawa |
Publisher | : CRC Press |
Total Pages | : 246 |
Release | : 1990-03-28 |
Genre | : Technology & Engineering |
ISBN | : 9780877626992 |
Download Delaware Composites Design Encyc Book in PDF, Epub and Kindle
Introduction to Anisotropic Elasticity - Special Applications: Mechanics of Anisotropic Materials - Micromodels for Continuous Fiber Composites - Micromodels for Particulate/Discontinuous Fiber Composites - Introduction to Viscoelasticity - Micromodels for Predicting Viscoelastic Behavior - Transport Properties
Author | : Mueller, Viktor |
Publisher | : KIT Scientific Publishing |
Total Pages | : 166 |
Release | : 2016-06-16 |
Genre | : Technology (General) |
ISBN | : 3731504545 |
Download Micromechanical modeling of short-fiber reinforced composites Book in PDF, Epub and Kindle
This work is focused on the prediction of elastic behavior of short-fiber reinforced composites by mean-field homogenization methods, which account for experimentally determined and artificially constructed microstructure data in discrete and averaged form. The predictions are compared with experimental measurements and a full-field voxel-based approach. It is investigated, whether the second-order orientation tensor delivers a sufficient microstructure description for such predictions.
Author | : Bhagwan D. Agarwal |
Publisher | : Wiley-Interscience |
Total Pages | : 480 |
Release | : 1990-10-08 |
Genre | : Technology & Engineering |
ISBN | : |
Download Analysis and Performance of Fiber Composites Book in PDF, Epub and Kindle
Having fully established themselves as workable engineering materials, composite materials are now increasingly commonplace around the world. Serves as both a text and reference guide to the behavior of composite materials in different engineering applications. Revised for this Second Edition, the text includes a general discussion of composites as material, practical aspects of design and performance, and further analysis that will be helpful to those engaged in research on composites. Each chapter closes with references for further reading and a set of problems that will be useful in developing a better understanding of the subject.
Author | : 蔡孟霖 |
Publisher | : |
Total Pages | : 0 |
Release | : 2022 |
Genre | : |
ISBN | : |
Download Stress-strain Curve Prediction of Short Fiber-reinforced Composites and Bio-inspired Layered Structural Composites Using Deep Neural Networks Book in PDF, Epub and Kindle
Author | : Lich Thanh Tran |
Publisher | : |
Total Pages | : 526 |
Release | : 1996 |
Genre | : |
ISBN | : |
Download Stress Relaxation in Polymer Matrix Composites Book in PDF, Epub and Kindle
Author | : S. Y. Yu |
Publisher | : CRC Press |
Total Pages | : 0 |
Release | : 2009-08-05 |
Genre | : Science |
ISBN | : 9781439810996 |
Download Science and Engineering of Short Fibre Reinforced Polymer Composites Book in PDF, Epub and Kindle
A summary of recent research on short fiber reinforced polymers, this book focuses on the fundamental mechanisms that govern the mechanical properties including strength, modulus, fracture toughness and thermal properties of SFRP materials. It covers extrusion compounding and injection molding, major factors affecting mechanical performance, stress transfer, strength, elastic modulus flexural modulus, thermal conductivity and expansion, non-linear stress-strain behavior and fracture mechanics of short fiber reinforced polymers. Written by a team of distinguished authors, it provides an in-depth understanding of the behavior of these versatile materials.