Search Results for longitudinal tension

Damping is the energy dissipation properties of a material or system under cyclic stress. The vibrational and damping characteristics of composites are important in many applications, including ground-based and airborne vehicles, space structures, and sporting goods. This article describes the damping characteristics of unidirectional composites, when they are subjected to longitudinal shear, longitudinal tension/compression, and transverse tension/compression. It presents equations that govern the overall damping capacity of beams that are cut from laminated plates. The article discusses the effect of temperature on damping and provides information on the relationship between damping and strength.

This article is an atlas of fractographs that helps in understanding the causes and mechanisms of fracture of metal-matrix composites, including tungsten fiber-reinforced aluminum, tungsten fiber-reinforced carbon steel, and tungsten fiber-reinforced silver. The fractographs illustrate the ductile fracture, interlaminar failure, transgranular cleavage and fracture, tension-overload fracture, longitudinal and transverse cracking, fiber splitting, stress rupture, and low-cycle fatigue of these composites.

This article presents a comprehendable and comprehensive physics-based approach for characterizing the strength of fiber-reinforced polymer composites. It begins with background information on the goals and attributes of this method. The article then addresses the characterization of fiber failures in laminates, because these are at the highest strengths that can be attained and, therefore, are usually the design objective. An exception would be if the design goal is to maximize energy absorption, rather than static strength. The discussion proceeds to situations in which the matrix fails first, either by intent, by design error, or because of impact damage. The state of the modeling propagation and arrest of matrix damage follows. Comparisons of this physics-based approach are then made to empirically based failure theories.

Metal production mills produce flat metal sheet and strip products into coil forms that are subjected to further fabrication for shape correction. This article provides a discussion on the principle of shape correction and describes the role of various fabrication processes in shape correction. These processes include flattening, leveling, slitting, and cut-to-length.

Relatively limited effort has gone into developing repair processes and materials for composites, in contrast to the significant labor and expense that has gone into the development of these materials for numerous critical applications. As composites gain wider acceptance as aerospace materials, there is a need to understand the requirements of the end users regarding repair of these advanced materials. This article focuses on the repair of graphite-epoxy structures designed in a variety of forms for a wide range of load intensities. Five repair concepts developed for generic laminate repair have been validated in this article through the required environmental and load condition tests. These include bonded-scarf joint flush repair, double-scarf joint flush repair, blind-side banded-scarf repair, blind-side sandwich repair, and bonded external patch repair. A brief note on thermoplastic repair concepts is also provided in this article.

This article discusses the standard test methods that can be applied to many types of welds: tension, bending, impact, and toughness testing. It provides information on four qualification stages, namely, the weld material qualification, base material qualification, the weld procedure qualification, and the weld service assessment. The article describes two general types of measurements for residual stress in welds: locally destructive techniques and nondestructive techniques. Locally destructive techniques include hole drilling, chip machining, and block sectioning. Nondestructive techniques include X-ray diffraction, neutron diffraction, Barkhausen noise analysis, and ultrasonic propagation analysis. The article concludes with an overview of weldability testing.

Fiber-matrix adhesion is a variable to be optimized in order to get the best properties and performance in composite materials. This article schematically illustrates fiber matrix interphase for composite materials. It discusses thermodynamics of interphase in terms of surface energy, contact angle, work of adhesion, solid surface energy, and wetting and wicking. The article describes the change in interphase depending on the reinforcing fiber such as glass fiber, polymeric fiber, and carbon fiber. It emphasizes fiber-matrix adhesion measurements by direct methods, indirect methods, and composite laminate tests. The effects of interphase and fiber-matrix adhesion on composite mechanical properties, such as composite on-axis properties, composite off-axis properties, and composite fracture properties, are also discussed.