Continuous Discontinuous Fiber Reinforced Polymers

Discontinuous long fiber reinforced polymer structures with local continuous fiber reinforcements represent an important class of lightweight materials with broad design possibilities and diverse technical applications, e.g. in vehicle construction. However, in contrast to continuous fiber reinforced composites, extensively used in the aircraft industry, there is still a lack of integrated and experimentally proven concepts for manufacture, modeling, and dimensioning of combinations of discontinuously and continuously reinforced polymer structures. This is partly ascribed to the complexity of the manufacturing processes of discontinuously reinforced polymers, with heterogeneous, anisotropic, and nonlinear material and structural properties, but also to the resulting bonding problem of both material types. This book addresses these issues, including both continuous and discontinuous fiber processing strategies. Specific design strategies for advanced composite reinforcement strategies are provided, with an integrated and holistic approach taken for composites material selection, product design, and mechanical properties. Characterization, simulation, technology, design, future research, and implementation directions are also included. Especially in the field of application of three-dimensional load-bearing structures, this book provides an excellent foundation for the enhancement of scientific methods and the education of engineers who need an interdisciplinary understanding of process and material techniques, as well as simulation and product development methods.

There are many books on composite material analysis, but most cover mainly continuous fiber materials, rather than those filled with discontinuous fibers, which are particularly attractive for large-volume and low-cost applications. This book provides the theoretical and practical background to design and use discontinuous fiber-reinforced polymer materials, with an emphasis on structural parts for the automotive industry. Moreover, the product of years of collaborative work between industry and academia is presented in an easy-to-use, comprehensive manner. The information provided makes it possible for someone with an engineering background to understand the micromechanics of discontinuous fiber-reinforced materials and, hence, analyze the structural performance of components designed with such materials. The book employs a practical approach to cover the key, unique capabilities that are critical for a successful structural analysis of discontinuous fiber-reinforced polymer structures: -Process simulation to estimate the condition of fibers in the finished parts, i.e., fiber length, orientation, and concentration -Capability to measure micro structure, i.e., fiber length distribution, fiber orientation tensors, and fiber concentration, etc. -Estimation of material properties in the part based on fiber condition, as well as environmental conditions such as temperature A broad range of areas is included, such as joining and assembly.

Discontinuous fiber-reinforced polymers have gained importance in the transportation industries due to their outstanding material properties, lower manufacturing costs and superior lightweight characteristics. One of the most attractive attributes of discontinuous fiber reinforced composites is the ease with which they can be manufactured in large numbers, using injection and compression molding processes. Typical processes involving discontinuous fiber reinforced thermoplastic composite materials include injection and compression molding processes as well as extrusion. Furthermore, the automotive and appliance industries also use thermosets reinforced with chopped fibers in the form of sheet molding compound and bulk molding compound, for compression and injection-compression molding processes, respectively. A big disadvantage of discontinuous fiber composites is that the configuration of the reinforcing fibers is significantly changed throughout production process, reflected in the form of fiber attrition, excessive fiber orientation, fiber jamming and fiber matrix separation. This process-induced variation of the microstructural fiber properties within the molded part introduces heterogeneity and anisotropies to the mechanical properties, which can limit the potential of discontinuous fiber reinforced composites for lightweight applications. The main aim of this Special Issue is to collect various investigations focused on the processing of discontinuous fiber reinforced composites and the effect processing has on fiber orientation, fiber length and fiber density distributions throughout the final part. Papers presenting investigations on the effect fiber configurations have on the mechanical properties of the final composite products and materials are welcome in the Special Issue. Researchers who are modeling and simulating processes involving discontinuous fiber composites as well as those performing experimental studies involving these composites are welcomed to submit papers. Authors are encouraged to present new models, constitutive laws and measuring and monitoring techniques to provide a complete framework on these groundbreaking materials and facilitate their use in different engineering applications.

This book is a printed edition of the Special Issue "Discontinuous Fiber Composites" that was published in J. Compos. Sci.

Discontinuous fiber-reinforced polymers have gained importance in transportation industries due to their outstanding material properties, lower manufacturing costs and superior lightweight characteristics. One of the most attractive attributes of discontinuous fiber-reinforced composites is the ease with which they can be manufactured in large numbers, using injection and compression molding processes. The main aim of this Special Issue is to collect various investigations focused on the processing of discontinuous fiber-reinforced composites and the effect that processing has on fiber orientation, fiber length and fiber density distributions throughout the final product. Papers presenting investigations on the effect that fiber configurations have on the mechanical properties of the final composite products and materials were welcome in the Special Issue. Researchers who model and simulate processes involving discontinuous fiber composites as well as those performing experimental studies involving these composites were welcomed to submit papers. The authors were encouraged to present new models, constitutive laws, and measuring and monitoring techniques to provide a complete framework on these groundbreaking materials and to facilitate their use in different engineering applications.

Multi-scale modelling of composites is a very relevant topic in composites science. This is illustrated by the numerous sessions in the recent European and International Conferences on Composite Materials, but also by the fast developments in multi-scale modelling software tools, developed by large industrial players such as Siemens (Virtual Material Characterization toolkit and MultiMechanics virtual testing software), MSC/e-Xstream (Digimat software), Simulia (micromechanics plug-in in Abaqus), HyperSizer (Multi-scale design of composites), Altair (Altair Multiscale Designer) This book is intended to be an ideal reference on the latest advances in multi-scale modelling of fibre-reinforced polymer composites, that is accessible for both (young) researchers and end users of modelling software. We target three main groups: This book aims at a complete introduction and overview of the state-of-the-art in multi-scale modelling of composites in three axes: • ranging from prediction of homogenized elastic properties to nonlinear material behaviour • ranging from geometrical models for random packing of unidirectional fibres over meso-scale geometries for textile composites to orientation tensors for short fibre composites • ranging from damage modelling of unidirectionally reinforced composites over textile composites to short fibre-reinforced composites The book covers the three most important scales in multi-scale modelling of composites: (i) micro-scale, (ii) meso-scale and (iii) macro-scale. The nano-scale and related atomistic and molecular modelling approaches are deliberately excluded, since the book wants to focus on continuum mechanics and there are already a lot of dedicated books about polymer nanocomposites. A strong focus is put on physics-based damage modelling, in the sense that the chapters devote attention to modelling the different damage mechanisms (matrix cracking, fibre/matrix debonding, delamination, fibre fracture,...) in such a way that the underlying physics of the initiation and growth of these damage modes is respected. The book also gives room to not only discuss the finite element based approaches for multi-scale modelling, but also much faster methods that are popular in industrial software, such as Mean Field Homogenization methods (based on Mori-Tanaka and Eshelby solutions) and variational methods (shear lag theory and more advanced theories). Since the book targets a wide audience, the focus is put on the most common numerical approaches that are used in multi-scale modelling. Very specialized numerical methods like peridynamics modelling, Material Point Method, eXtended Finite Element Method (XFEM), isogeometric analysis, SPH (Smoothed Particle Hydrodynamics),... are excluded. Outline of the book The book is divided in three large parts, well balanced with each a similar number of chapters:

The main objective of this work is to significantly deepen the understanding of the material and the structural behaviour of continuous-discontinuous SMC composites, following a holistic approach to investigate microscopic aspects, macroscopic mechanical behaviour as well as failure evolution at the coupon, structure and component level. In addition, criteria to evaluate the effect of hybridisation are introduced and modelling approaches are presented and discussed.