Search Results for composite structural system

This article describes the role of the full-scale testing in assessing composite structural systems of aircraft and qualifying them for in-service use. The typical full-scale tests include static, durability, and damage tolerance. The article discusses the parameters to be considered when developing the basic requirements for the static test. These parameters consist of material considerations, moisture and temperature effects, structure size, load application alternatives, instrumentation requirements, test procedure considerations, ultimate load requirements, and test results correlation. The basic requirements common for durability and damage tolerance tests, including environmental effects and inspection requirements, are also discussed.

Composites, particularly fiber-reinforced polymer materials, are increasingly being adopted or considered as alternatives to conventional materials for civil infrastructure applications, such as bridges, buildings, waterfront structures, waste treatment facilities, and facilities for transmission and transport of utilities. This article provides information on seismic retrofit applications and discusses the repair and strengthening of components, such as beams, slabs, large-diameter pipes, and bridge decks.

This article highlights the selected applications of advanced polymer-matrix composites, metal-matrix composites, and ceramic matrix composites.

Spinodal transformation is a phase-separation reaction that occurs from kinetic behavior. This article discusses the theory of spinodal decomposition, and outlines the methods used in the characterization of spinodal structures in metal matrices.

This article presents the binary eutectic phase diagram to understand the various structures that evolve in a binary eutectic system during solidification. It describes the various classifications and solidification principles of the eutectic structures. The formation of halos in eutectic microstructures of most alloy systems is also discussed.

This article discusses the advantages of polymer matrix composite for automotive application in terms of design drivers, noise, vibration, harshness efficiency, process materials property constraints, safety and reliability, design optimization, structural and appearance requirements, recyclability, and processability. It describes the properties of high-volume composites used in automotive industries. The article provides a discussion on state-of-the-art and developing technologies in automotive field.

Rehabilitation is the process of repairing or modifying reinforced concrete structures to a desired useful condition. This article describes the operational steps for the structural assessment of reinforced concrete structures. It discusses the classification of composite materials reinforcing systems for strengthening reinforced concrete structures, such as shop-manufactured and field-manufactured structures. The article reviews the materials property requirements for designing reinforcing systems to strengthen the reinforced concrete structures. It discusses the fiber-reinforced polymer (FRP)-reinforced concrete behavior that depends on flexural, shear, or axial failures. Surface preparation procedures for rehabilitation techniques of reinforced concrete structures using bonded FRP materials are also discussed. The article provides information on the applications of rehabilitation of concrete structures. It explains data recording and acceptance criteria for rehabilitation of concrete structures with composite materials.

Honeycomb-cored sandwich panels increase part stiffness at a lower weight than monolithic composite materials. This article illustrates an area of a honeycomb-cored sandwich structure composite cross section that is viewed using transmitted polarized light. This area shows the differences in the constituents and resin intermingling. The article discusses the factors that govern the honeycomb core movement and honeycomb core crush, with illustrations. Some common tests performed on honeycomb composites to characterize the skin-to-core bond strength are the climbing drum peel and flatwise tensile tests. The article concludes with a description on the reasons for core failure, which are analyzed after these tests.

Of the many different nondestructive evaluation (NDE) techniques, ultrasonic inspection continues to be the leading nondestructive method for inspecting composite materials, because measurements can be quantitative and the typical defect geometries and orientations lend themselves to detection and characterization. This article focuses on the three common methods for ultrasonic nondestructive inspection of plastics, namely pitch-catch, through-transmission, and pulse-echo, as well as the three basic types of ultrasonic NDE scans: the A-scan, B-scan, and C-scan. The discussion includes the linear and phased array systems that are sometimes used for large-scale inspection tasks to reduce scan times, the various gating and image processing techniques, and how ultrasonic data are interpreted and presented. A brief section on future trends in ultrasonic inspection is presented at the end of the article.

This article provides a summary of the concepts discussed in the articles under the Section “Product Reliability, Maintainability, and Repair” in ASM Handbook, Volume 21: Composites. The Section covers a range of topics that include the general issues for reliability, maintenance, and repair of composite structures. Specific structural applications, including marine, infrastructure, and aircraft related issues, are discussed. Operators of equipment employing composite structures in primary load applications must understand the issues with respect to maintenance and repair action. The Section also provides information on these requirements.

This article presents the importance of progressing from post-manufacturing inspection/verification to in-process inspection/verification methods. It lists the various quality assurance factors considered for typical composite laminate lay-up process. The article provides information on composite cure tooling that is fabricated from steel, aluminum, or high-temperature composite materials. The quality assurance for commercial applications is reviewed. The article concludes with a discussion on data fusion systems designed to provide nondestructive analysis data from fabrication and assembly processes for each individual composite part.

This article discusses composites for unmanned space vehicles and provides an overview of key design drivers, challenges, and environment for use of composites in spacecraft, launch vehicles, and missiles. It describes the design allowable properties of composite materials. The article provides information on the specific state-of-the-art applications of composite materials for spacecraft missiles and launch vehicles. A discussion on the key applications, including solid rocket motor casings, payload fairings, and payload support structures, is presented.

This article provides information on the potential applications of fiber-reinforced polymer (FRP) composites for maritime craft and offshore drilling platforms. The key benefits gained from using FRP materials together with an examination of the drawbacks and major issues impeding the more widespread use of composites in marine structures are presented.

Alloy phase diagrams are useful for the development, fabrication, design and control of heat treatment procedures that will produce the required mechanical, physical, and chemical properties of new alloys. They are also useful in solving problems that arise in their performance in commercial applications, thus improving product predictability. This article describes different equilibrium phase diagrams (unary, binary, and ternary) and microstructures, description terms, and general principles of reading alloy phase diagrams. Further, the article discusses plotting schemes; areas in a phase diagram; and the position and shapes of the points, lines, surfaces, and intersections, which are controlled by thermodynamic principles and properties of all phases that comprise the system. It also illustrates the application of the stated principles with suitable phase diagrams.

The crystal structure of a material is an important aspect of corrosion and oxidation processes. This article provides a general introduction to the crystal structure of materials, providing information on the crystal systems, lattice dimensions, nomenclature, and solid-solution mechanisms used to characterize structures. It illustrates the unit cells and ion positions for some simple metal crystals, arranged alphabetically according to the Pearson symbol. The space lattice and crystal system, space-group notation, and prototype for each crystal are also illustrated.

Cyanate ester resins are a family of high-temperature thermosetting resins that bridge the gap in thermal performance between engineering epoxy and high-temperature polyimides. This article discusses the chemistry, properties and characteristics of the cyanate ester resins. It describes the processing procedures for the cyanate ester resins and provides information on properties for selected applications, such as space applications, radomes, and printed circuit boards.

This article discusses three typical repair types for composite structures: temporary repairs, adhesively bonded repairs, and bolted repairs. It contains a table that lists general design requirements and considerations for the repair of composite structures. The article describes ten steps for an engineering repair approach to effectively restore structural integrity to damaged composite components. Management, validation and certification of repairs are also discussed. The article presents the design guidelines for analyzing the damage and possible strategies for making a repair. It reviews three repair schemes used in repair design analysis, namely, core replacement, adhesively bonded patch, and mechanically fastened patch. The article also emphasizes the various pitfalls and problems in repair design for composite structures.

This article discusses bismaleimide (BMI) chemistry and the use of BMI in composites. An analysis of the applications illustrates how the advantages of BMIs have been exploited and perhaps suggests how these advantages might be extended to other applications. The article describes the mechanical properties of BMI composites. BMIs suitable for resin transfer molding processing are provided. The article concludes with information on the elevated-temperature applications of 5250-4 BMI system.

Good hole-drilling processes are key to joining composite parts with other composite parts or with metal parts. This article discusses the considerations for drilling polymer-matrix composites. It describes the use of power-feed drill motors and automated drilling/fastener installation equipment. The article provides a discussion on reaming, countersinking, and three recommended choices of cutting tools for producing a countersink in carbon/epoxy structure. The cutting tools include: standard carbide insert cutters, solid carbide cutters, or polycrystalline diamond (PCD) insert cutters. The article concludes with a discussion on inspection of hole quality.

The application of phase diagrams is instrumental in solid-state transformations for the processing and heat treatment of alloys. A unary phase diagram plots the phase changes of one element as a function of temperature and pressure. This article discusses the unary system that can exist as a solid, liquid, and/or gas, depending on the specific combination of temperature and pressure. It describes the accomplishment of conversion between weight percentage and atomic percentage in a binary system by the use of formulas. The article analyzes the effects of alloying on melting/solidification and on solid-state transformations. It explains the construction of phase diagrams by the Gibbs phase rule and the Lever rule. The article also reviews the various types of alloy systems that involve solid-state transformations. It concludes with information on the sources of phase diagram.