Virtual Principles in Aircraft Structures


Book Description

The basic partial differential equations for the stresses and displacements in clas sical three dimensional elasticity theory can be set up in three ways: (1) to solve for the displacements first and then the stresses; (2) to solve for the stresses first and then the displacements; and (3) to solve for both stresses and displacements simultaneously. These three methods are identified in the literature as (1) the displacement method, (2) the stress or force method, and (3) the combined or mixed method. Closed form solutions of the partial differential equations with their complicated boundary conditions for any of these three methods have been obtained only in special cases. In order to obtain solutions, various special methods have been developed to determine the stresses and displacements in structures. The equations have been reduced to two and one dimensional forms for plates, beams, and trusses. By neglecting the local effects at the edges and ends, satisfactory solutions can be obtained for many case~. The procedures for reducing the three dimensional equations to two and one dimensional equations are described in Chapter 1, Volume 1, where the various approximations are pointed out.




Analysis of Aircraft Structures


Book Description

As with the first edition, this textbook provides a clear introduction to the fundamental theory of structural analysis as applied to vehicular structures such as aircraft, spacecraft, automobiles and ships. The emphasis is on the application of fundamental concepts of structural analysis that are employed in everyday engineering practice. All approximations are accompanied by a full explanation of their validity. In this new edition, more topics, figures, examples and exercises have been added. There is also a greater emphasis on the finite element method of analysis. Clarity remains the hallmark of this text and it employs three strategies to achieve clarity of presentation: essential introductory topics are covered, all approximations are fully explained and many important concepts are repeated.




Aircraft Structures for Engineering Students


Book Description

This book provides a self-contained course in aircraft structures which contains not only the fundamentals of elasticity and aircraft structural analysis but also the associated topics of airworthiness and aeroelasticity.




The Behavior of Shells Composed of Isotropic and Composite Materials


Book Description

Shell structures are used in all phases of structures, from space vehicles to deep submergence hulls, from nuclear reactors to domes on sport arenas and civic buildings. With new materials and manufacturing methods, curved thin walled structures are being used increasingly. This text is a graduate course in the theory of shells. It covers shells of isotropic materials, such as metal alloys and plastics, and shells of composite materials, such as fibre reinforced polymer, metal or ceramic matrix materials. It provides the essential information for an understanding of the underlying theory, and solution of some of the basic problems. It also provides a basis to study the voluminous shell literature. Beyond being primarily a textbook, it is intended also for self study by practising engineers who would like to learn more about the behaviour of shells. The book has two parts: Part I deals with shells of isotropic materials. In this part the mathematical formulations are introduced involving curvilinear coordinates. The techniques of solutions and resulting behavior is compared to planar thin walled isotropic structures such as plates and beams. Part II then treats the behavior of shells, involving anisotropic composite materials, so widely used today. The analysis involves the complications due to the many elastic constants, effects of transverse shear deformation, thermal thickening and offer effects arising from the properties of composite materials.




Optimization of Cam Mechanisms


Book Description

1. 1 Preliminary Concepts A cam mechanism is a mechanical system consisting of three basic components: a driving element, called the cam; a driven element, termed the follower; and a fixed frame. Sometimes, an intermediate element is introduced between the cam and the follower with the purpose of improving the mechanism performance. This element is called the roller because function is to produce a pure-rolling relative motion be tween the cam and the follower. The purpose ofa cam mechanism is the transmission of power or information. In applications concerning power transmission, the main good to be transmitted is force or torque; in applications ofinformation transmission, the main good transmitted takes the form of motion signals. Most modern appli cations of cam mechanisms, to be described shortly, are of the former type. Cam mechanisms used for information transmission were traditionally found in measuring instruments. With the advent ofmodern microprocessor-based hardware, this typeof application is becoming less common. Nevertheless, cam mechanisms are still used in a wide spectrum of applications, especially in automatic machines and instruments, textile machinery, computers, printing presses, food-processing equipment, internal combustion engines, control systems, and photographic equipment (Prenzel, 1989). In the design of cam mechanisms, the engineer performs several activities, namely, task definition, synthesis, analysis, optimization, and dynamic simulation. These tasks do not always follow this order. In fact, some loops may appear in the foregoing tasks, such as those illustrated in Fig. 1. 1. 1.




Piezoelectric Shells


Book Description

Exploiting new advanced structures and electromechanical systems, e. g. , adaptive structures, high-precision systems, micro electromechanical systems, distributed sensors/actuators, precision manipulation and controls, etc. , has been becoming one of the mainstream research and development activities (structure & motion) in recent years. These new systems and devices could bring a new technological revolution in modern industries and further, directly or indirectly, impact human life. In the search for and research in innovative technologies, it is proved that piezoelectric materials are very versatile in both sensor and actuator applications. Consequently, piezoelectric technology has been widely applied to a large number of industrial applications and devices, varying from thin-film micro sensors/actuators to large space structures in addition to those relatively conventional applications, e. g. , sensors, actuators, hydrophones, precision manipulators, mobile robots, micro motors, etc. There have been a few books on piezoelectricity published in the past; however, a unified presentation of piezoelectric shells and distributed senSing/control applications is still lacking. This book is intended to fill the gap and to pro~de practising engineers and researchers with an introduction to advanced piezoelectric shell theories and distributed sensor/actuator technologies in structural identification and control. This book represents a collection of the author's recent research and development on piezoelectric shells and related applications to distributed measurement and control of continuaj it reflects six best-paper awards, including [ xviii] • Contents. two ASME Best-Paper Awards in recent years.




IUTAM Symposium on Micromechanics of Plasticity and Damage of Multiphase Materials


Book Description

The IUT AM Symposium on "Micromechanics of Plasticity and Damage of Multiphase Materials" was held in Sevres, Paris, France, 29 August - 1 September 1995. The Symposium was attended by 83 persons from 18 countries. In addition 17 young French students attended the meeting. During the 4 day meeting, a total of 55 papers were presented, including 24 papers in the poster sessions. The meeting was divided into 7 oral and 3 poster sessions. The 7 oral sessions were the following: - Plasticity and Viscoplasticity I and II; - Phase transformations; - Damage I and II; - Statistical and geometrical aspects; - Cracks and interfaces. Each poster session was introduced by a Rapporteur, as follows: - Session I (Plasticity and Viscoplasticity): G. Cailletaud; - Session 2 (Damage): D. Franc;:ois; - Session 3 (Phase transformation; statistical and geometrical aspects): D. Jeulin. The main purpose of the Symposium was the discussion of the state of the art in the development of micromechanical models used to predict the macroscopic mechanical behaviour of mUltiphase solid materials. These materials consist of at least two chemically different phases, present either initially or formed during plastic deformation, when a strain-induced phase transformation takes place. One session was devoted to the latter case. Continuously strengthened composite materials, containing long fibers, were out of the scope of the Symposium.




Profitable Condition Monitoring


Book Description

To engineer and manufacture is human. Manufactured goods are subjected to severe international competitive forces. Consumers' perceptions towards total quality, reliable performance, health and safety, environmental issues, energy conservation and cost of ownership are changing day by day. Manufacturers have no alternative but to satisfy the consumer's increasing demands with maximum efficiency and profitability with minimum delay. Failure to meet such a challenge is clearly undesirable and will, no doubt, result in the closure of manufacturing activities, which is still regarded by many as the backbone of our national economy. Manufacturing for profitability should be the number one concern of all serious minded and responsible people. To help the industries to meet these challenges and to manage efficiently well into 1990s and beyond, the Technical Advisory Committee in their wisdom decided the appropriate theme, Profitable Condition Monitoring, for this year's International Conference, to coincide with the great European market to be opened in 1993. The benefits from condition monitoring are well documented. Condition monitoring is now an affordable technology which is waiting to be fully exploited by all sectors of industry, both big and small. Many companies have realised the following benefits from condition monitoring: • optimisation of profits • maximisation of production • cost-effective maintenance • minimisation of product liability • maximisation of total quality. As the contents of this proceedings reveal, there have been a number of significant advances in condition monitoring of which companies ought to be taking full advantage.




Advances in Turbulence V


Book Description

Under the auspices of the Euromech Committee, the Fifth European Turbulence Conference was held in Siena on 5-8 July 1994. Following the previous ETC meeting in Lyon (1986), Berlin (1988), Stockholm (1990) and Delft (1992), the Fifth ETC was aimed at providing a review of the fundamental aspects of turbulence from a theoretical, numerical and experimental point of view. In the magnificent town of Siena, more than 250 scientists from all over the world, spent four days discussing new ideas on turbulence. As a research worker in the field of turbulence, I must say that the works presented at the Conference, on which this book is based, covered almost all areas in this field. I also think that this book provides a major opportunity to have a complete overview of the most recent research works. I am extremely grateful to Prof. C. Cercignani, Dr. M. Loffredo, and Prof. R. Piva who, as members of the local organizing committee, share the success of the Conference. I also want to thank Mrs. Liu' Catena, for her invaluable contribution to the work done by the local organizing committee and the European Turbulence Committee in the scientific organization of the meeting. The "Servizio Congressi" of the University of Siena provided perfect organization in Siena and wonderful hospitality. The Conference has been supported by CNR, Cira, Alenia, the Universities of Rome "Tor Vergata" and "La Sapienza".




Jet Cutting Technology


Book Description

This volume contains papers presented at the 11th International Conference on Jet Cutting Technology, held at St. Andrews, Scotland, on 8-10 September 1992. Jetting techniques have been successfully applied for many years in the field of cleaning and descaling. Today, however, jet cutting is used in operations as diverse as removing cancerous growths from the human body, decommissioning sunsea installations and disabling explosive munitions. The diversity is reflected in the papers presented at the conference. The papers were divided into several main sections: jetting basics -- materials; jetting basics -- fluid mechanics; mining and quarrying; civil engineering; new developments; petrochem; cleaning and surface treatment; and manufacturing. The high quality of papers presented at the conference has further reinforced its position as the premier event in the field. The volume will be of interest to researchers, developers and manufacturers of systems, equipment users and contractors.