properties of materials "those characteristics that help identify and distinguish one material...

Properties of Materials "those characteristics that help

identify and distinguish one material from another” (p. 140)

Page numbers are in reference to: Jacobs, James A. and Thomas F. Kilduff. (2005). Engineering materials technology, 5th Edition. Englewood Cliffs, NJ: Prentice-Hall, Inc.

Physical Properties properties that "result from the

response of the material to some environmental variable." (p.140)

Physical properties Density & Specific Gravity Porosity Color Other

Mechanical Properties "a measure of a material's ability

to carry or resist mechanical forces or stresses.” (p. 140)

Stress "the resistance offered by a

material to external forces or loads.” (p.141)

sigma = F / A

Strain "change in a physical

dimension . . . Deformation.” (p.142)

unit deformation. (p.142)

Stress-Strain Diagrams (p.144) Elastic Region Plastic Region Yield Point Ultimate Strength Fracture

FIGURE 4-4 Engineering symbols for the sides of the triangle shown in the elastic region of the curve, 2 (theta) is the slope angle, E is the Modulus of elasticity or Young’s Modulus and is computed: E = = tan and is the symbol that means “a measurable change in.” Stress–strain diagram.

James A. Jacobs & Thomas F. KilduffEngineering Materials Technology, Fourth Edition

Copyright ©2001 by Prentice-Hall, Inc.

Upper Saddle River, New Jersey 07458

All rights reserved.

Modulus of Elasticity "the ratio of the stress to the strain

in the elastic region of the stress-strain diagram." (p.145)

AKA: Young’s Modulus, MOE, E

FIGURE 4-6 Typical stress-strain diagrams.





Strength tensile compressive shear torsion other

Calculating Strength Strength = max. load / cross-sectional

area

(psi) pounds square inches

(pascals) newtons square meters

Tensile Strength or ultimate strength p. 146

FIGURE 4-3 (a) Rod under a tensile load. (b) Standard tensile test specimen or gage.





Yield Strength stress that produces 0.002 in/in

strain p.146

Resilience the amount of energy that a

material can absorb without plastic deformation.

p.147

Ductility the ability to "undergo large plastic

deformation without fracture.” (also, the ability to be drawn into a

wire.) (p.149)

FIGURE 4-10 Stress-strain curves for (a) ductile material.





FIGURE 4-10 Stress-strain curves for (b) brittle material.





Toughness "the ability or capacity of a

material to absorb energy during plastic deformation.” (p.152)

Influenced by temperature

Malleability, workability (p.156)

Flexural or Bending Strength (p.157)

Beam bending Compression, Tension, & Neutral

axis

FIGURE 4-18 A simple beam deflected by a cyclic, transverse load.





Fatigue Strength (p.158) Endurance

FIGURE 4-21 s-N diagram for a typical fiberglass composite material.





FIGURE 4-22 s-N diagram for a typical low-carbon steel.





Shear Strength Single or Double

FIGURE 4-9 Shearing stress and strain. See Figure 4-10 for sheet metal shearing. (a) Before shear load. (b) After shear load.





Creep "a slow process of plastic

deformation that takes place when a material is subjected to a constant condition of loading (stress) below its normal yield strength." (p.163)

(cf. bookshelves)

Torsion "the process of twisting." (p.164)

FIGURE 4-27 (b) Torsional fracture. Torsional (twisting) loads produce spiral types of failure. Note the curved line from (A) to (C) is part of a helix.





Hardness "a measure of a material's

resistance to penetration (local plastic deformation) or scratching." (p.167)

Hardness testing instrumentation Hardness scales

FIGURE 4-30 (a) Photograph of Tukon microhardness tester (Measurement Systems Div., Page Wilson Corp.)





FIGURE 4-30 (b) Photograph of Rockwell hardness tester. (Measurement Systems Div., Page Wilson Corp.)





FIGURE 4-30 (c) Photograph of Air-O-Brinell metal hardness tester with digital readout of Brinell values. (Tinius Olsen Testing Machine Co.)





FIGURE 4-30 (d) Microhardness penetrator (Knoop and Vickers) indentations. (Wilson Instrument Division of ACCO)





FIGURE 4-30 (e) Various standard loads for the Rockwell harness tester. (Wilson Instrument Division of ACCO)





FIGURE 4-30 (f) Brale sphero-conical diamond penatrator. (Wilson Instrument Division of ACCO)









Hardness Scales (p. 168)

Chemical Properties (p.176) oxidation corrosion resistance acid/alkali resistance behavior in chemical reactions other

Oxidation "the interaction of oxygen with

elements in a material to cause structural changed due to the movement of valence electrons in the atoms of the material. An oxidized material loses electrons from atoms or ions." (p.183)

(The opposite of oxidation is reduction.)

Corrosion Resistance "the ability to resist

oxidation." (p.185)

pH acid --> alkali 0 to 14 7 is neutral (pure water) H+ or OH- ions H2SO4, HCl, HNO3 NaOH, Ca(OH)2

Other Properties Other Chemical Properties Thermal Properties (p.194)

Specific heat Coefficient of linear thermal expansion

Electrical Properties Magnetic Properties Optical Properties Other Properties

Materials Testing Purpose Type

Destructive Non-destructive

Standards ANSI and ASTM

FIGURE 4-51 Potential weight savings trend for future structural materials. (NASA)





FIGURE 4-1 (a) Cryogenic processing coupled with coatings of engine parts in race cars has increased the life of high performance race cars three to five times.





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