Fatigue and Tribological Properties of Plastics and Elastomers

Laurence W. McKeen

• Publisher: William Andrew
• Year: 2016
• eBook ISBN: 9780323442053
• Edition: 3
• Topic: Tecnología e ingeniería
• Subtopic: Ingeniería mecánica

Part of a series of data-rich handbooks within the Plastics Design Library, Fatigue and Tribological Properties of Plastics and Elastomers provides a comprehensive collection of graphical multipoint data and tabular data covering the fatigue and tribological performance of plastics. The handbook is structured by grouping together plastics of similar polymer types into ten chapters. Each of these chapters is split into two sections: Fatigue Properties and Tribological Properties, and together they provide a compendium of several hundred graphs and charts, supplying the core data needed by engineers and scientists on a day-to-day basis. The data for this third edition has been updated to cover upwards of five years since the previous edition was published, and also includes an entirely new chapter covering sustainable and biodegradable polymers. The book also includes an extensive introductory section covering fatigue, what it is and how it is measured; the fundamentals of tribology; polymer chemistry and plastics composition. These chapters also provide readers with a full understanding of the data section, and how to put it to use as a hard-working information tool.

1

Introduction to Fatigue of Plastics and Elastomers

Abstract

This chapter is an introduction to fatigue as it occurs in plastic materials. It is an introductory tutorial. It starts with an explanation of the types of stress. Then follows the section on fatigue testing. This includes the types of coupons used along with many types of testing machines. An explanation of the analysis of the fatigue-testing data is included. A section covers the fatigue process that includes crack growth and propagation. External factors, those not directly about plastic composition, that affect fatigue performance are summarized.

Keywords

stress

tensile

compressive

torsional

flexural

bending

hoop

fatigue coupons

eccentric fatigue

cantilevered

flex life

MIT Flex

Ross Flex

DeMattia Flex

crack initiation

crack growth

crack propagation

monotonic

stress–strain

strain–life

stress–life

There are two recently published books on the properties of engineering plastics in this series. The Effect of Temperature and Other Factors on Plastics, Plastics Design Library [1] discusses the general mechanical properties of plastics. The mechanical properties as a function of temperature, humidity, and other factors are presented in graphs or tables. That work includes hundreds of graphs of stress versus strain, modulus versus temperature, impact strength versus temperature, etc. Time was not a factor in that book. The Effect of Creep and Other Time Related Factors on Plastics, Plastics Design Library [2] discusses the long-term behavior of plastics when exposed to constant stresses or strains for long periods of time. This book adds another two layers of plastics performance criteria, fatigue and tribology.

This book provides graphical multipoint data and tabular data on fatigue and tribological properties of plastics and elastomers along with introductory background to help in understanding those data. This chapter deals with the types of stress and an introduction to fatigue. Tribology is discussed in chapter: Introduction to the Tribology of Plastics and Elastomers. The chemistry of plastics follows in chapter: Introduction to Plastics and Polymers. The remaining chapters contain the data.

The idea of fatigue is very simple. If an object is subjected to a stress or deformation, and it is repeated, the object becomes weaker. This weakening of plastic material is called fatigue and occurs when the material is subject to alternating stresses, over a long period of time.

1.1. Types of Stress

Fatigue occurs as a result of rapidly changing stress or strain. Stress and strain can be applied in a number of ways. Normal stress (σ) is the ratio of the applied force (F) over the cross-sectional area (A) as shown in Eq. (1.1) and Fig. 1.1:

$\sigma =\frac{F}{A}$

(1.1)

Figure 1.1 Illustration of tensile stress and compressive stress.

1.1.1. Tensile and Compressive Stress

When the applied force is directed away from the part, as shown in Fig. 1.1, it is a tensile force inducing ...

Table of contents

• Cover
• Title page
• Table of Contents
• Copyright
• Foreword
• Acknowledgments
• 1: Introduction to Fatigue of Plastics and Elastomers
• 2: Introduction to the Tribology of Plastics and Elastomers
• 3: Introduction to Plastics and Polymers
• 4: Styrenic Plastics
• 5: Polyether Plastics
• 6: Polyester Plastics
• 7: Polyimide Plastics
• 8: Polyamide Plastics (Nylons)
• 9: Polyolefins and Acrylics
• 10: Thermoplastic Elastomers
• 11: Fluoropolymers
• 12: High-Temperature Polymers
• Subject Index