Search Results for laminate thickness

This chapter outlines a methodology for the design of cylindrical pressure vessels, with emphasis on the establishment of winding patterns and the interaction between the real fiber bed geometry (finite roving dimensions) and the theoretical one. To highlight the materials-shape/pattern-roving interaction, an outline of the basic principles of pressure vessel design is provided. After a short section on laminate thickness approximation techniques (essential for establishing a range of acceptable roving dimensions), the chapter concludes with an example demonstrating the methodology from an initial set of design parameters up to the final stage, including patterns, roving dimensions, and production time minimization.

This chapter provides an overview of the tools and techniques, as well as some of the underlying theory, that have proven useful for process modeling and simulation. It begins by presenting the framework of a thermoset cure model that accounts for kinetics, viscosity, heat transfer, flow, voids, and residual stress. It then discusses each variable in detail, explaining how it affects the cure process, how it is measured, and how it can be expressed mathematically in the form of a simple model. The discussions throughout the chapter are supported by numerous images, diagrams, and data plots.

This chapter discusses the use of mechanical fastening and adhesive bonding, the primary methods for joining polymer matrix composites. It describes and analyzes the basic types of mechanically fastened joints, including single-hole and multirow bolted composite joints. It then reviews the advantages and disadvantages of adhesively bonded joints and compares and contrasts the long-term performance of various joint designs. The chapter also discusses the merits of stepped-lap and bonded-bolted joints.

This chapter discusses some of the challenges associated with the analysis of composite structures. It begins with a review of lamina fundamentals and the stress-strain relationships in a single ply under various types of loads. It demonstrates the use of classical lamination theory, discusses the effects of interlaminar free-edge stresses, and explains how to predict the failure of composites using stress and strain criteria as well as the Azzi-Tsai-Hill maximum work theory and the Tsai-Wu failure criterion.

This chapter discusses the use of nondestructive inspection methods, including visual, ultrasonic, radiographic, and thermographic techniques, and the types of flaws and damages they can reveal in composite parts and assemblies. It describes the basic principles behind each method along with best practices and procedures.

This chapter discusses design and certification considerations, including materials and process selection, the building block approach to certification, design allowables, and design guidelines. It also includes information on damage tolerance and environmental sensitivity.

Unlike metals, in which fatigue failures are due to a single crack that grows to a critical length, the effects of fatigue in composites are much more distributed and varied. As the chapter explains, there are five major damage mechanisms that contribute to the progression of composite fatigue, those being matrix cracking, fiber breaking, crack coupling, delamination initiation, and delamination growth. The chapter describes each mechanism in detail along with related factors. It also discusses the primary differences between composites and metals, the effect of manufacturing defects, damage tolerance, and testing and certification.

This chapter discusses the failure mechanisms associated with fiber-reinforced composites. It begins with a review of fiber-matrix systems and the stress-strain response of unidirectional lamina and both notched and unnotched composite laminate specimens. It then explains how cyclic loading can lead to delamination, the primary failure mode of most composites, and describes some of the methods that have been developed to improve delamination resistance, assess damage tolerance, determine residual strength, and predict failure modes.

Achieving the best-performing composite part requires that the processing method and cure cycle create high-quality, low-void-content structures. If voids are present, the performance of the composite will be significantly reduced. There are multiple causes of voids in composite materials; they are generally categorized as voids that are due to volatiles (such as solvents, water) or voids that result from entrapped air. This chapter describes the analysis of various types of voids. It reviews techniques for analysis of voids at ply-drops, voids due to high fiber packing, and voids that occur in honeycomb core composites. The final section of the chapter discusses void documentation through the use of nondestructive inspection techniques and density/specific gravity measurement methods.

Composite systems for cryogenic applications are discussed in this chapter. This chapter emphasizes filamentary-reinforced composites because they are the most widely used composite materials. It begins with a discussion on the approach to designing and fabricating with low-pressure laminate composites. This is followed by a section providing an overview of the materials in modern cryogenic technology. Then, the chapter describes the effect of cryogenic temperatures on materials properties; it also introduces the various joining techniques developed for composite materials. The effects of radiation on the properties of the materials are covered as well as the processes involved in testing laminates at cryogenic temperatures. Finally, the chapter provides information available on concrete aggregate composites.

The objective of mechanical testing of an engineered material is to provide data necessary for the analysis, design, and fabrication of structural components using the material. The testing of filament-wound composite materials offers unique challenges because of the special characteristics of composites. This chapter describes suitable static mechanical test techniques for characterizing laminated composite materials. The approach is to provide recommended techniques, based on consensus opinions of fabricators and users of filament-wound composites, and to survey available techniques that have been used successfully in the field. The chapter describes the effects of various factors on the properties of composite constituents, including fibers, resins, and unidirectional plies. Some aspects of specimen selection are also described. The chapter provides information on pressure bottles and tubular parts that have been developed as standard test specimens for combined load testing of composites.

This chapter presents the fundamentals of tensile testing of fiber-reinforced polymer composites. Basic tensile testing of polymer composites is divided into lamina and laminate testing. The chapter focuses on tensile testing of laminates. It discusses the most common tensile test methods that have been standardized for fiber-reinforced composite materials. It also briefly reviews considerations in tensile testing of metal-matrix composites.

This chapter discusses composite testing procedures, including tension, compression, shear, flexure, and fracture toughness testing as well as adhesive shear, peel, and honeycomb flatwise tension testing. It also discusses specimen preparation, environmental conditioning, and data analysis.

To a large extent, the induction coil and its coupling to the workpiece determine the precise heating pattern that is developed. However, it is often desirable to modify this pattern in order to produce a special heating distribution or to increase energy efficiency. At other times, the high heating rates of induction are needed for processing nonconductors. This chapter describes broad methods of accomplishing such objectives: modification of the field of magnetic induction, use of devices to prevent auxiliary equipment or certain portions of a workpiece from being heated, and techniques to apply heating to electrically nonconductive materials. These methods make use of devices such as flux concentrators, shields, and susceptors. The chapter provides a description of the materials for these devices and guidelines for their application.