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2020 | Buch

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Structural Durability: Methods and Concepts

Enabling Cost and Mass Efficient Products

verfasst von: Dr. Ruediger Heim

Verlag: Springer International Publishing

Buchreihe : Structural Integrity

Enthalten in: Springer Professional "Wirtschaft+Technik" , Springer Professional "Technik" , Springer Professional "Wirtschaft"

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Über dieses Buch

This book provides methods and concepts which enable engineers to design mass and cost efficient products. Therefore, the book introduces background and motivation related to sustainability and lightweight design by looking into those aspects from a durability and quality point of view. Hence this book gives a "top-down" approach: What does an engineer has to do for providing a mass and cost efficient solution? A central part of that approach is the "stress-strength interference model" and how to deal with "stresses" (caused by operational loads) as well as with the "strength" of components (provided by material, design and manufacturing process). The basic concepts of material fatigue are introduced, but the focus of the volume is to develop an understanding of the content and sequence of engineering tasks to be performed which help to build reliable products. This book is therefore aimed specifically at students of mechanical engineering and mechatronics and at engineers in professional practice.

Inhaltsverzeichnis

Frontmatter

Chapter 1. Motivation

Abstract

Sustainability is a widely used, yet new degree subject that attempts to bridge social science with future technologies. Often, we think about reducing carbon emissions and protecting the environment, while driving innovation and not compromising the way of life we are used to live. For transport and mobility, we have to look for systems and solutions which provide a much better eco-friendliness than everything what we did in the past. But it is not only about electric vehicles and renewable fuel sources: Transportation is much about lightweighting and energy efficiency too. Hence, there is a strong need for methods and concepts to design ready to manufacture, lightweight, yet durable enough to withstand the rigors of challenging use. In the first chapter of this book, emphasis is placed on the impact of lightweight design for energy savings in transportation that is the hidden background of structural durability.

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Chapter 2. Operating Life Analysis

Abstract

An operating life analysis is the backbone of managing structural durability successfully and, thus, the focus of this chapter. Therefore, the understanding of the component’s strength behavior as well as of the loads to the structure is necessary. The stress–strength interference is introduced which equally relies on the analysis of the loads and the characteristics of the structure. Hence, load and stress analyses are described in this chapter as well as fundamental strength behavior and fatigue are introduced. We will learn to bring the results into a consistent form and to perform a damage calculation that answers the question as to whether the design is safe and durable enough.

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Chapter 3. Influencing Factors for Fatigue Strength

Abstract

Metal fatigue is a weakened condition induced by repeated stresses which ultimately results in cracks or even fracture and, thus, has to be understood in terms of its influencing factors. In this chapter, the fatigue strength of materials and components will be reviewed including the major parameters which have an effect on the number of cycles-to-failure. Material- and process-related effects will be discussed as well as stress concentration and surface conditions. A major proportion of this chapter is related to the effects of mean stresses and residual stresses to demonstrate effective measures for improving fatigue strength and, thus, optimizing lightweight design.

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Chapter 4. Fatigue Strength Under Spectrum Loading

Abstract

In-service loading often is characterized by random variable amplitudes which cannot be represented by sinusoidal type of loading sufficiently. Rare events may introduce microplastic straining and are followed by a huge number of cycles with moderate to medium stresses. In such a way, in-service loading creates its unique history and may lead to an early termination of serviceability. Chapter 4 looks into fundamental contexts of variable amplitude loading and how to deal with stress analysis. Finite element analysis is introduced, because as an engineer nowadays it does not bear thinking about being without. Hence, a major part is devoted to the fatigue analysis of welded joints which is an excellent playing field to look at nominal stress, structural stress and local stress concepts.

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Chapter 5. Structural Durability

Abstract

Finally, we will look into durability growth strategies and accelerated testing: In this chapter, materials and structures get an application background and, thus, testing is continued with structural coupons and full-scale components. Time- and cost-efficient life testing is enabled by a proper combination of usage rate and overstress acceleration which is introduced in this final part of the book. Z-scores help to design the conditions of testing and yet to manage the probability of failure for the product verification and validation process. A complete method for the structural durability evaluation of wheels is described and opposed to simplified wheel fatigue tests to finally present the value of service load simulation for optimizing products. Looking beyond ‘safe life’ leads then to fracture mechanics which is manageable for safety-relevant components too: A study of the crack growth of a rail vehicle axle provides an outlook for the application of damage tolerance concepts.

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Backmatter

Titel: Structural Durability: Methods and Concepts
verfasst von: Dr. Ruediger Heim
Verlag: Springer International Publishing
Electronic ISBN: 978-3-030-48173-5
Print ISBN: 978-3-030-48172-8
DOI: https://doi.org/10.1007/978-3-030-48173-5

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