Introduction to Impact Dynamics

T. X. Yu, Xinming Qiu

• Publisher: Wiley
• Year: 2017
• Print ISBN: 9781118929841
• eBook ISBN: 9781118929865
• Edition: 1
• Topic: Physical Sciences
• Subtopic: Mechanics

Fundamental guidance—including concepts, models, and methodology—for better understanding the dynamic behavior of materials and for designing for objects and structures under impact or intensive dynamic loading

This book introduces readers to the dynamic response of structures with important emphasis on the material behavior under dynamic loadings. It utilizes theoretical modelling and analytical methods in order to provide readers with insight into the various phenomena. The content of the book is an introduction to the fundamental aspects, which underpin many important industrial areas. These areas include the safety of various transportation systems and a range of different structures when subjected to various impact and dynamic loadings, including terrorist attacks.

Presented in three parts—Stress Waves in Solids, Dynamic Behaviors of Materials Under High Strain Rate, and Dynamic Response of Structures to Impact and Pulse Loading— Introduction to Impact Dynamics covers elastic waves, rate dependent behaviors of materials, effects of tensile force, inertial effects, and more. The book also features numerous case studies to aid in facilitating learning. The strength of the book is its clarity, balanced coverage, and practical examples, which allow students to learn the overall knowledge of impact dynamics in a limited time whilst directing them to explore more advanced technical knowledge and skills.

• Considers both the dynamic behavior of materials and stress waves, and the dynamic structural response and energy absorption, emphasizing the interaction between material behavior and the structural response
• Provides a comprehensive description of the phenomenon of impact of structures, containing both fundamental issues of wave propagation and constitutive relation of materials, and the dynamic response of structures under impact loads
• Based on the authors' research and teaching experience as well as updated developments in the field

Introduction to Impact Dynamics is the perfect textbook for graduate and postgraduate students, and will work as a reference for engineers in the fields of solid mechanics, automotive design, aerospace, mechanical, nuclear, marine, and defense.

Part 1
Stress Waves in Solids

1
Elastic Waves

In a deformable solid medium, the disturbance to mechanical equilibrium is represented by the change in particle velocity and the corresponding changes in stress and strain states. When some parts of a solid are first disturbed, finite time durations are required for this disequilibrium to be felt by other parts of the body, due to the deformable properties of the body. This kind of propagation as a result of the disturbance in stress and strain through a solid body is termed a stress wave.

1.1 Elastic Wave in a Uniform Circular Bar

1.1.1 The Propagation of a Compressive Elastic Wave

Consider a uniform circular bar made of isotropic material, as shown in Figure 1.1. Let x denote the longitudinal coordinate measured from an origin O, which is fixed in the space; and let u(x) denote the displacement undergone by a plane AB in the bar, which is initially at a distance x from O. Then

is the displacement of plane A′B′ which is parallel to AB but is initially at a distance

from O.

Figure 1.1 The propagation of a compressive elastic wave in a uniform circular bar.

A force applied rapidly at time t = 0, over the end plane at x = 0, will cause a disturbance to propagate elastically along the bar, so that a compressive normal stress,

, will pass through plane AB at time t.

It should be noted that the slender bar assumption is adopted here, i.e. the pulse length is at least six times the typical cross‐sectional dimension of the bar. In this case, the strain and inertia in the transverse direction can be neglected. The gravitational force and damping of the material are also ignored in the following analysis.

The equilibrium of a representative element of the bar is illustrated in Figure 1.2. Here A₀ is the initial cross‐section area of the bar, ρ₀ is the initial density of the material, and

is the stress transmitted, with the negative sign reflecting the fact that the stress is compressive, as shown in the figure.

Figure 1.2 The equilibrium of a representative e...

Table of contents

• Cover
• Title Page
• Table of Contents
• Preface
• Introduction
• Part 1: Stress Waves in Solids
• Part 2: Dynamic Behavior of Materials under High Strain Rate
• Part 3: Dynamic Response of Structures to Impact and Pulse Loading
• References
• Index
• End User License Agreement