Preface forced composite material will emerge as a highly competitive family of materials for all those applications where the structural behaviour and weight are critical. The aims of this book are to describe the manufacturing processes,to highlight the advantages,to identify the main applications,to analyse the methods for prediction of mechanical properties and,finally,to focus on the key technical aspects of these promising candidates in order to know better how to exploit their main features and overcome their disadvantages in relation to the laminated composite materials. The present book focuses on the textile technologies,which use 3-D textile reinforcements for composite materials.Manufacturing techniques, design methodologies,key application fields and specific issues are studied. The first chapter is devoted to the general description of the 3-D fabrics for composite materials.The typologies available will be described and the manufacturing techniques are also explained. The needs of the transportation industry provide the most powerful reasons for the development of new materials since weight,stiffness,fatigue strength and energy absorption constitute the key design factors.The second chapter analyses the 3-D textile reinforcements for the transporta- tion industry. The analysis of the 3-D textile reinforcements is more complex than that for unidirectional and 2-D fabrics composite materials.In our case,both micro-and macromechanical analyses must be developed.The micro- mechanical study is essential to determine the behaviour of the material in a fibre scale.The stiffness and strength properties must be determined as a function of type of fibre and matrix,fibre fraction,interface and fibre configuration.Chapters 3 and 4 are devoted to micro-and macromechani- cal analyses,respectively. The composite grid structure constitutes an amazingly efficient system to combine high stiffness and strength with lightness for high load-bearing composite applications.In the present system,the 3-D reinforcement is obtained by the inclusion of a system of ribs in the core of the material and the implementation of two outer skins.Both in-plane and out-of-plane stresses can be controlled by a proper sizing of the skins and an adequate design of the ribs.Chapter 5 discusses this type of reinforcement. Chapter 6 analyses knitted fabric composites.The knitting system is one of the most interesting manufacturing techniques for reinforcing the com- posite material in the thickness direction.By an appropriate design of the knitted fibres,both interlaminar normal and shear stresses can be easily controlled. The braiding technique is a very efficient method for reinforcing a large number of composite structures.Plates,beams,profiles and 3D structures can be braided nowadays,the result being a robust structure in terms offorced composite material will emerge as a highly competitive family of materials for all those applications where the structural behaviour and weight are critical. The aims of this book are to describe the manufacturing processes, to highlight the advantages, to identify the main applications, to analyse the methods for prediction of mechanical properties and, finally, to focus on the key technical aspects of these promising candidates in order to know better how to exploit their main features and overcome their disadvantages in relation to the laminated composite materials. The present book focuses on the textile technologies, which use 3-D textile reinforcements for composite materials. Manufacturing techniques, design methodologies, key application fields and specific issues are studied. The first chapter is devoted to the general description of the 3-D fabrics for composite materials. The typologies available will be described and the manufacturing techniques are also explained. The needs of the transportation industry provide the most powerful reasons for the development of new materials since weight, stiffness, fatigue strength and energy absorption constitute the key design factors. The second chapter analyses the 3-D textile reinforcements for the transporta￾tion industry. The analysis of the 3-D textile reinforcements is more complex than that for unidirectional and 2-D fabrics composite materials. In our case, both micro- and macromechanical analyses must be developed. The micro￾mechanical study is essential to determine the behaviour of the material in a fibre scale. The stiffness and strength properties must be determined as a function of type of fibre and matrix, fibre fraction, interface and fibre configuration. Chapters 3 and 4 are devoted to micro- and macromechani￾cal analyses, respectively. The composite grid structure constitutes an amazingly efficient system to combine high stiffness and strength with lightness for high load-bearing composite applications. In the present system, the 3-D reinforcement is obtained by the inclusion of a system of ribs in the core of the material and the implementation of two outer skins. Both in-plane and out-of-plane stresses can be controlled by a proper sizing of the skins and an adequate design of the ribs. Chapter 5 discusses this type of reinforcement. Chapter 6 analyses knitted fabric composites. The knitting system is one of the most interesting manufacturing techniques for reinforcing the com￾posite material in the thickness direction. By an appropriate design of the knitted fibres, both interlaminar normal and shear stresses can be easily controlled. The braiding technique is a very efficient method for reinforcing a large number of composite structures. Plates, beams, profiles and 3D structures can be braided nowadays, the result being a robust structure in terms of x Preface RICPR 7/10/99 7:08 PM Page x