Mechanics of Materials:

William F. Riley, Leroy D. Sturges, & Don H. Morris


Book Cover

Introduction/Purpose

The primary objectives of a course in mechanics of materials are:
  1. to develop a working knowledge of the relations between the loads applied to a nonrigid body made of a given material and the resulting deformations of the body;
  2. to develop a thorough understanding of the relations between the loads applied to a nonrigid body and the stresses produced in the body;
  3. to develop a clear insight into the relations between stress and strain for a wide variety of conditions and materials;
  4. to develop adequate procedures for finding the required dimensions of a member of a specified material to carry a given load subject to stated specifications of stress and deflection.
These objectives involve the concepts and skills that form the foundation of all structural and machine design.

The principles and methods used to meet the general objectives are drawn largely from prerequisite courses in mechanics, physics, and mathematics together with the basic concepts of the theory of elasticity and the properties of engineering materials. This book is designed to emphasize the required fundamental principles, with numerous applications to demonstrate and develop logical orderly methods of procedure. Instead of deriving numerous formulas for all types of problems, we have stressed the use of free-body diagrams and the equations of equilibrium, together with the geometry of the deformed body, and the observed relations between stress and strain, for the analysis of the force system acting on a body.

This book is designed for a first course in mechanics of deformable bodies. Because of the extensive subdivision into different topics, the book will provide flexibility in the choice of assignments to cover courses of different length and content. The developments of structural applications include the inelastic as well as the elastic range of stress; however, the material is organized so that the book will be found satisfactory for elastic coverage only.

Organization

Since most mechanics of materials problems begin with a statics problem (finding the forces in structural members or the forces in pins connecting structural members), we have included a review of statics in Chapter 1 of this book. The coverage is perhaps more complete and comprehensive than would be necessary for review so that the book could be used for both statics and mechanics of materials if desired.

After the review of statics in Chapter 1, Chapters 2 and 3 consist of a thorough discussion of material stress and strain including principal stresses and principal strains. We choose to present principal stresses and principal strains at this early position to make it easier to talk about maximum stresses in the axial, torsional, and flexural applications that follow. It also allows us to talk about the maximum stresses in combined loading situations in Chapters 5, 6, and 7, rather than waiting until the end of the book.

Material properties and the relationship between stress and strain are presented in Chapter 4. In Chapters 5, 6, and 7, we consider the stresses and strains in axial, torsional, and flexural loading applications. In addition to calculating the stresses in members subjected to axial loading and the stresses in pressure vessels subjected to internal pressure, in Chapter 5 we also calculate the stresses in pressure vessels subjected to an axial load. In addition to calculating the stresses in circular shafts subjected to torsional loading, in Chapter 6 we also calculate the stresses in circular shafts subjected to axial loads and in pressure vessels subjected to torsional loads. In Chapter 7 we first calculate the normal and shear stresses in beams subjected to flexural loading. We conclude Chapter 7 with the calculation of stresses in circular shafts subjected to a combination of axial, torsional, and flexural loads.

In Chapter 8 we calculate the deflection of beams due to various loading situations and also cover the calculation of support reactions for and stresses in statically indeterminate beams. In Chapter 9 we consider the tendency of columns to buckle. Finally, in Chapter 1`0 we discuss theories of failure and the use of energy methods.

Every chapter opens with a brief Introduction and ends with a Summary of important concepts covered in the chapter followed by a set of Review Problems. All principles are illustrated by one or more Example Problems and several Homework Problems. The Homework Problems are graded in difficulty and are separated into groups of Introductory, Intermediate, and Challenging problems. Several sections of Homework Problems also have a set of Computer Problems. While the computation could be accomplished by the student writing a FORTRAN program, the computation could just as easily be carried out using MathCAD, Mathematica, or a spreadsheet program. The important concept of the computer problems is that they require students to analyze how the solution depends on some parameter of the problem.

Most chapters conclude with a section on Design which includes Example Problems and a set of Homework Problems. The emphasis in these problems is that there are often more than just one criteria to be satisfied in a design specification. An acceptable design must satisfy all specified criteria. In addition, standard lumber, pipes, beams, etc. come in specific sizes. The student must choose an appropriate structural member from these standard materials. Since each different choice of a beam or a piece of lumber has a different specific weight and affects the overall problem differently, students are also introduced to the idea that design is an iterative process.

Free-Body Diagrams

We strongly feel that a proper free-body diagram is just as important in mechanics of materials as it is in statics. It is our approach that, whenever an equation of equilibrium is written, it must be accompanied by a complete, proper free-body diagram. Furthermore, since the primary purpose of a free-body diagram is to show the forces acting on a body, the free-body diagram should not be used for any other purpose. We encourage students to draw separate diagrams to show deformation and compatibility relationships.

Problem-Solving Procedures

Students are urged to develop the ability to reduce problems to a series of simpler component problems that can be easily analyzed and combined to give the solution of the initial problem. Along with an effective methodology for problem decomposition and solution, the ability to present results in a clear, logical, and neat manner is emphasized throughout the text.

Homework Problems

A large number of homework problems are included so that problem assignments may be varies from term to term. The problems in each set represent a considerable range of difficulty and are grouped and labeled as "Introductory", "Intermediate", "Challenging", and "Computer".

U.S. customary units and SI units are used in approximately equal proportions in the text for both Example Problems and Homework Problems. To help the instructor who wants to assign problems of one type or the other, odd-numbered Homework Problems are in U.S. customary units and even-numbered Homework Problems are in SI units.

Answers to about half of the Homework Problems are included at the end of the book. Since the convenient designation of problems for which answers are provided is of great value to those who make up assignment sheets, the problems for which answers are provided are indicated by means of an asterisk (*) after the problem number.


Sample Syllabi

Because we have been asked, we make available the following abbreviated syllabi for courses using our Mechanics of Materials text. The following pointers are to 60-hour (6 quarter credit or 4 semester credit), 75-hour (5 semester credit), 90-hour (9 quarter credit or 6 semester credit) variants of a Mechanics of Materials syllabus.

These syllabi are purposely vague and obviously are only a few of the many variations possible. More detailed syllabi will depend on whether the courses are intended primarily for civil engineering students or for mechanical engineering students; on whether the courses are primarily taken by freshman students or sophomore students; on whether the students will be taking additional mechanics courses or not; etc.

However, we hope that these brief outlines will be useful to instructors as you make up your syllabi.


30 Hour An abbreviated syllabus for a 3 quarter credit Mechanics of Materials course.

40 Hour An abbreviated syllabus for a 4 quarter credit Mechanics of Materials course.

45 Hour An abbreviated syllabus for a 3 semester credit Mechanics of Materials course.

50 Hour An abbreviated syllabus for a 5 quarter credit Mechanics of Materials course.

50 Hour An abbreviated syllabus for a 5 quarter credit Mechanics of Materials course (with a very brief review of statics).

60 Hour An abbreviated syllabus for a 6 quarter credit or a 4 semester credit Mechanics of Materials course.

60 Hour An abbreviated syllabus for a 6 quarter credit or a 4 semester credit Statics and Mechanics of Materials course.

75 Hour An abbreviated syllabus for a 5 semester credit Mechanics of Materials course.

75 Hour An abbreviated syllabus for a 5 semester credit Statics and Mechanics of Materials course.

80 Hour An abbreviated syllabus for an 8 quarter credit Mechanics of Materials course.

90 Hour An abbreviated syllabus for a 9 quarter credit or a 6 semester credit Mechanics of Materials course.


Comments and suggestions should be sent to:
Mail-to
sturges@iastate.edu
Leroy D. Sturges
2019 Black Engineering
Iowa State University
Ames, Iowa 50011-2162
515-294-6242


Note Tab ©1998, Leroy D. Sturges (revised 3 August 1998)