Page 77 - Manufacturing Engineering and Technology - Kalpakjian, Serope : Schmid, Steven R.

Mechanical

Behavior, Testing,
M
L|.l
l-' and Manufacturing
L

<1 Properties of
I

U Materials

2.l Introduction 56
2.2 Tension 57 ° This chapter examines the effects of external forces on the behavior of materials,
2.3 Compression 66 and the test methods employed in determining various mechanical properties.
2.4 Torsion 67 ° The tension test is described first. This test is commonly used for quantifying a
2.5 Bending(Flexure) 68
2.6 Hardness 68 number of material parameters, including elastic modulus, yield stress, ultimate
2.1 Fatigue 74 strength, ductility, and toughness.
2.8 Creep 75 ° Compression tests are then described. These tests are useful because they more
2.9 Impact 75 closely simulate manufacturing processes; nonetheless, they have the unavoid-
2.I0 Failure and Fracture
able drawback of contributing friction to the testing.
of Materials in
Manufacturing ° Bending tests are particularly useful for brittle materials; three- and four-point
and in Service 76
tests are in common use.
2.II Residual Stresses 8|
2.l2 Work, Heat, and ° Hardness and the variety of hardness tests and their applicability are then
Temperature 82 explored.
EXAMPLES: ° Fatigue involves the failure of material due to cyclic or repeating loads, whereas
2.l Calculation of Ultimate creep is deformation due to the application of a constant load over an extended
Tensile Strength 63 period.
2.2 Calculation of Modulus
of Resilience from ° The chapter ends with descriptions of the types of, and factors involved in, failure
Hardness 72 and fracture of materials.

2.| Introduction

In manufacturing operations, numerous parts and components are formed into dif-
ferent shapes by applying external forces to the workpiece, typically by means of var-
ious tools and dies. Common examples of such operations are forging turbine disks,
extruding various components of aluminum ladders, drawing wire for making nails,
and rolling metal to make sheets for car bodies. Forming operations may be carried
out at room temperature or at elevated temperatures, and at a low or a high rate of
deformation. These operations are also used in forming and shaping nonmetallic
materials such as plastics and ceramics, as described throughout this book.
As indicated in Table 1.2, a wide variety of metallic and nonmetallic materials
is now available, with an equally wide range of properties, as shown qualitatively in
Table 2.1. This chapter covers those aspects of mechanical properties and behavior
of metals that are relevant to the design and manufacturing of products and includes
commonly used test methods employed in assessing various properties.
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