Analysis of process-induced distortions and residual stresses of composite structures


Book Description

The increased application of composite materials in lightweight structures leads to new integral design of structural parts, using the example of, an integral composite landing flap of an Airbus A320 aircraft. This offers possibilities to simplify the process chain, to decrease manufacturing costs and to have fibre fair structural design. The critical disadvantage of large integral designs is that process-induced deformations are a risk factor during the design phase of the manufacturing process, because rework is not always possible. Especially, the aircraft industry with its demands on high qualities / tolerances and the application of hot curing resin systems, requires knowledge-based methods for virtual process design to avoid time- and effort-consuming iterations. This thesis contributes to the understanding of the mechanism behind process-induced distortions and stresses related to the Resin Transfer Moulding (RTM) manufacturing process. The aim is to comprehend the phenomena, to identify related parameters and to present compensation strategies.




Residual Stresses in Composite Materials


Book Description

Residual stresses are a common phenomenon in composite materials. They can either add to or significantly reduce material strength. Because of the increasing demand for high-strength, light-weight materials such as composites and their wide range of applications in the aerospace and automotive industries, in civil infrastructure and in sporting applications, it is critical that the residual stresses of composite materials are understood and measured correctly. The first part of this important book reviews destructive and non-destructive testing (NDT) techniques for measuring residual stresses. Various mathematical (analytical and numerical) methods for calculation of residual stresses in composite materials are also presented. Chapters in the first section of the book discuss the simulated hole drilling method, the slitting/crack compliance method, measuring residual stresses in homogeneous and composite glass materials using photoelastic techniques, and modeling residual stresses in composite materials. The second part of the book discusses residual stresses in polymer matrix, metal-matrix and a range of other types of composites. Moreover, the addition of nanoparticles to the matrix of polymeric composites as a new technique for reduction of residual stresses is discussed. Residual stresses in composite materials provides a comprehensive overview of this important topic, and is an invaluable reference text for both academics and professionals working in the mechanical engineering, civil engineering, aerospace, automotive, marine and sporting industries. Reviews destructive and non-destructive testing (NDT) techniques for measuring residual stresses Discusses residual stresses in polymer matrix, metal-matrix and other types of composite Considers the addition of nanoparticles to the matrix of polymeric composites as a new technique for reduction of residual stresses




Residual Stress Measurement and the Slitting Method


Book Description

This book provides complete coverage of the slitting method. It details new results in analysis, computation, and estimation and discusses different roles of residual stresses from the fracture mechanics perspective. It provides detailed formulations and examples of compliance functions, weighted least squares fit and convergence test in stress estimation, and computer programs to facilitate the implementation of the slitting method.




Numerical prediction of curing and process-induced distortion of composite structures


Book Description

Fiber-reinforced materials offer a huge potential for lightweight design of load-bearing structures. However, high-volume production of such parts is still a challenge in terms of cost efficiency and competitiveness. Numerical process simulation can be used to analyze underlying mechanisms and to find a suitable process design. In this study, the curing process of the resin is investigated with regard to its influence on RTM mold filling and process-induced distortion.




Modeling Methods for Process Induced Distortions of CFRP-Parts produced in the Prepreg-Autoclave-Process


Book Description

Process induced distortions are a challenge in the production of high-performance components made of carbon fiber reinforced plastics. In order to prevent the distortions, a prediction is of great utility. For components manufactured in the prepreg autoclave process, which is often used in the aerospace industry, prediction methods are investigated within this work. First, the state of the art is discussed and, based on this, two promising approaches are identified, which are further investigated and implemented: A rapid simulation approach and a complex one, which requires more effort but allows further investigations of the distortions. For the latter approach, new material models and rules of mixture are developed that take into account modern material architectures with interleaf layers. Using these material models, the observed material behavior can be represented more accurately than with material models from the literature. The results obtained by both approaches are compared with experimental results. A good agreement can be shown between the measurements and the simulation.




Introduction to Composite Materials Design, Second Edition


Book Description

Presenting a wealth of completely revised examples and new information, Introduction to Composite Materials Design, Second Edition greatly improves on the bestselling first edition. It incorporates state-of-the-art advances in knowledge and design methods that have taken place over the last 10 years, yet maintains the distinguishing features and vital content of the original. New material in this second edition: Introduces new background topics, including design for reliability and fracture mechanics Revises and updates information on polymer matrices, modern fibers (e.g., carbon nanotubes, Basalt, Vectran) and fiber forms such as textiles/fabrics Includes new information on Vacuum Assisted Resin Transfer Molding (VARTM) Incorporates major advances in prediction of unidirectional-lamina properties Reworks sections on material failure, including the most advanced prediction and design methodologies, such as in situ strength and Mohr-Coulomb criterion, etc. Covers all aspects of preliminary design, relegating finite element analysis to a separate textbook Discusses methodology used to perform damage mechanics analysis of laminated composites accounting for the main damage modes: longitudinal tension, longitudinal compression, transverse tension, in-plane shear, and transverse compression Presents in-depth analysis of composites reinforced with plain, twill, and satin weaves, as well as with random fiber reinforcements Expands the analysis of thin walled beams with newly developed examples and MATLAB® code Addresses external strengthening of reinforced-concrete beams, columns, and structural members subjected to both axial and bending loads The author distributes 78 fully developed examples throughout the book to illustrate the application of presented analysis techniques and design methodology, making this textbook ideally suited for self-study. Requiring no more than senior undergraduate-level understanding of math and mechanics, it remains an invaluable tool for students in the engineering disciplines, as well as for self-studying, practicing engineers.




Analysis of Composite Structures


Book Description

This book provides the basis for calculations of composite structures, using continuum mechanics to facilitate the treatment of more elaborate theories. A composite structure combines traditional materials (such as concrete) with new materials (such as high performance fibres) to explore and develop new structures.The author deals with individual layers in laminate composites, discussing the basic laws that govern mixtures. · Recommended for both student and professional use · A systematic, compact presentation in a single volume· Covers the governing equations of composite beams, plates and structures




Residual Stresses 2016


Book Description

This book presents the proceedings of the International Conference on Residual Stresses 10 and is devoted to the prediction/modelling, evaluation, control, and application of residual stresses in engineering materials. New developments, on stress-measurement techniques, on modelling and prediction of residual stresses and on progress made in the fundamental understanding of the relation between the state of residual stress and the material properties, are highlighted. The proceedings offer an overview of the current understanding of the role of residual stresses in materials used in wide ranging application areas.




Composite Reinforcements for Optimum Performance


Book Description

Composite Reinforcements for Optimum Performance, Second Edition, has been brought fully up to date with the latest developments in the field. It reviews the materials, properties and modelling techniques used in composite production and highlights their uses in optimizing performance. Part I covers materials for reinforcements in composites, including chapters on fibers, carbon nanotubes and ceramics as reinforcement materials. In Part II, different types of structures for reinforcements are discussed, with chapters covering woven and braided reinforcements, three-dimensional fibre structures and two methods of modelling the geometry of textile reinforcements: WiseTex and TexGen. Part III focuses on the properties of composite reinforcements, with chapters on topics such as in-plane shear properties, transverse compression, bending and permeability properties. Finally, Part IV covers the characterization and modelling of reinforcements in composites, with chapters focusing on microscopic and mesoscopic approaches, X-ray tomography analysis and modelling reinforcement forming processes. With its distinguished editor and international team of contributors, Composite Reinforcements for Optimum Performance, Second Edition, is an essential reference for designers and engineers working in the composite and composite reinforcement manufacturing industry, as well as all those with an academic research interest in the subject. Discusses the characterization and modeling of reinforcements in composites, focusing on such topics as microscopic and mesoscopic approaches, X-ray tomography analysis, and modeling reinforcement forming processes Provides comprehensive coverage of the types and properties of reinforcement in composites, along with their production and performance optimization Includes sections on NCF (non-crimp fabrics), natural fiber reinforcements, tufting composite reinforcements, sustainability, multiscale modeling, knitted reinforcements, and more




Residual Stresses in Composite Materials


Book Description

The residual stress is a common phenomenon in composite materials. They can either add to or significantly reduce material strength. Because of the increasing demand for high-strength, lightweight materials such as composites and their wide range of applications; it is critical that the residual stresses of composite materials are understood and measured correctly. The first edition of this book consists of thirteen chapters divided into two parts. The first part reviews destructive and non-destructive testing (NDT) techniques for measuring residual stresses. There are also additional chapters on using mathematical (analytical and numerical) methods for the calculation of residual stresses in composite materials. These include the simulated hole drilling method, the slitting/crack compliance method, measuring residual stresses in homogeneous and composite glass materials using photoelastic techniques, and modeling residual stresses in composite materials. The second part of the book discusses measuring residual stresses in different types of composites including polymer and metal matrix composites. The addition of nanoparticles to the matrix of polymeric composites as a new technique for the reduction of residual stresses is also discussed. In the Second Edition of this book, each of the original chapters of the first edition has been fully updated, taking into account the latest research and new developments. There are also five new chapters on the theoretical and experimental studies of residual stresses in the composite integrated circuits; residual stresses in additive manufacturing of polymers and polymer matrix composites; residual stresses in metal matrix composites fabricated by additive manufacturing; the eigenstrain based method for the incremental hole-drilling technique; and the estimation of residual stresses in polymer matrix composites using the digital image correlation technique. Residual Stresses in Composite Materials, Second Edition, provides a unique and comprehensive overview of this important topic and is an invaluable reference text for both academics and professionals working in the mechanical engineering, civil engineering, aerospace, automotive, marine, and sporting industries. Presents the latest developments on theoretical and experimental studies of residual stresses in composites Reviews destructive and non-destructive testing (NDT) techniques for measuring residual stresses Discusses residual stresses in the polymer matrix, metal matrix, and ceramic matrix composites Considers the addition of nanoparticles to the matrix as a new technique for reduction of residual stresses in polymeric composites Introduces the latest advancements of research on the residual stresses in additive-manufactured polymer and metal matrix composites