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[email protected] • ENGR-45_Lec-14_Metal_MechProp-1.ppt1
Bruce Mayer, PE Engineering-45: Materials of Engineering
Bruce Mayer, PERegistered Electrical & Mechanical Engineer
Engineering 45
Mechanical Mechanical Properties of Properties of
Metals (1)Metals (1)
[email protected] • ENGR-45_Lec-14_Metal_MechProp-1.ppt2
Bruce Mayer, PE Engineering-45: Materials of Engineering
Learning Goals.1 – Mech PropsLearning Goals.1 – Mech Props
STRESS and STRAIN: • What they are and why they are they used
instead of LOAD and DEFORMATION
ELASTIC Behavior• How Much Deformation occurs when
Loads are SMALL?
• Which Materials Deform Least
[email protected] • ENGR-45_Lec-14_Metal_MechProp-1.ppt3
Bruce Mayer, PE Engineering-45: Materials of Engineering
Learning Goals.2 – Mech PropsLearning Goals.2 – Mech Props
PLASTIC Behavior• Determine the point at which dislocations
cause permanent deformation
• Which materials are most resistant to permanent deformation
TOUGHNESS and Ductility• What they are
• How to Measure them
[email protected] • ENGR-45_Lec-14_Metal_MechProp-1.ppt4
Bruce Mayer, PE Engineering-45: Materials of Engineering
Materials TestingMaterials Testing
In The USA the American Society for Testing and Materials (ASTM) Sets Many, Many Materials-Test Standards
Founded in 1898, ASTM International is a not-for-profit organization that provides a global forum for the development and publication of voluntary consensus standards for materials, products, systems, and services. Over 30,000 individuals from 100 nations are the members of ASTM International, who are producers, users, consumers, and representatives of government and academia. In over 130 varied industry areas, ASTM standards serve as the basis for manufacturing, procurement, and regulatory activities. FormerlyFormerly known as the American Society for Testing and Materials, ASTM InternationalASTM International provides standards that are accepted and used in research and development, product testing, quality systems, and commercial transactions around the globe.
[email protected] • ENGR-45_Lec-14_Metal_MechProp-1.ppt5
Bruce Mayer, PE Engineering-45: Materials of Engineering
ELASTIC DeformationELASTIC Deformation Apply/Remove a SMALL Force Load to a Specimen
1. Initial 3. Unload
return to initial
2. SMALL load
bonds stretch
F
• F Force Load
(lb or N) Deformation in
Response to the Load (in or m)
F
Linear- elastic
Non-Linear-elastic
ELASTIC means REVERSIBLE
[email protected] • ENGR-45_Lec-14_Metal_MechProp-1.ppt6
Bruce Mayer, PE Engineering-45: Materials of Engineering
PLASTIC DeformationPLASTIC Deformation Apply/Remove a LARGE Force Load to a Specimen
PLASTIC means PERMANENT
1. Initial 3. Unload
PlanesStillSheared
& planes
2. LARGE load
bonds stretch
shear
F
elastic+plasticplastic
F
linear elastic
linear elastic
plastic
[email protected] • ENGR-45_Lec-14_Metal_MechProp-1.ppt7
Bruce Mayer, PE Engineering-45: Materials of Engineering
Engineering Stress, Engineering Stress, Normalize Applied-Force to Supporting Area TENSILE Stress, σ
Area, A
Ft
Ft
FtAo
original area before loading
SHEAR Stress,
Area, A
Ft
Ft
Fs
F
F
Fs FsAo
• Engineering Stress Units → N/m2 (Pa) or lb/in2 (psi)
[email protected] • ENGR-45_Lec-14_Metal_MechProp-1.ppt8
Bruce Mayer, PE Engineering-45: Materials of Engineering
5
• Simple tension: cable
o
FA
• Simple shear: drive shaft
o
FsA
Note: = M/AoR here.
Ski lift (photo courtesy P.M. Anderson)
Common States Of StressCommon States Of Stress
Ao = cross sectional Area (when unloaded)
FF
M
M Ao
2R
FsAc
[email protected] • ENGR-45_Lec-14_Metal_MechProp-1.ppt9
Bruce Mayer, PE Engineering-45: Materials of Engineering
Canyon Bridge, Los Alamos, NM
6
• Simple COMPRESSION:
Note: These areCOMPRESSIVEstructural members(σ < 0; i.e., a NEGATIVEnumber)
(photo courtesy P.M. Anderson)
Common Stress States cont.1Common Stress States cont.1
Ao
(photo courtesy P.M. Anderson)
Balanced Rock, Arches National Park o
FA
[email protected] • ENGR-45_Lec-14_Metal_MechProp-1.ppt10
Bruce Mayer, PE Engineering-45: Materials of Engineering
Common Stress States cont.2Common Stress States cont.2 BIAXIAL Tension
z > 0
> 0Pressurized tank(photo courtesyP.M. Anderson)
Tank Surface
HYDROSTATIC Compression
Fish under water(photo courtesyP.M. Anderson)
< 0h
SurfaceElement
[email protected] • ENGR-45_Lec-14_Metal_MechProp-1.ppt11
Bruce Mayer, PE Engineering-45: Materials of Engineering
Engineering Strain, Engineering Strain,
LATERAL Strain
/2
/2
L/2L/2
Lowo
Lo
L L
wo
SHEAR Strain
Engineering STRAIN Units → NONE (Dimensionless)• To Save Writing Exponents
– µ-in/in– µm/m
TENSILE Strain
90º
90º -
x = x/y = tan
y
[email protected] • ENGR-45_Lec-14_Metal_MechProp-1.ppt12
Bruce Mayer, PE Engineering-45: Materials of Engineering
Tensile Testing – Cyl SpecimenTensile Testing – Cyl Specimen Std Specimen Tension Tester
3/4
-10
Th
d
Other Tests• Compression Test for
Brittle Materials– e.g.; Concrete → GREAT in
Compression, Fractures in Tension/Shear
• Torsion (twist) Test– Drive Shafts, Torsion Bars
for Vehicle Suspension
[email protected] • ENGR-45_Lec-14_Metal_MechProp-1.ppt13
Bruce Mayer, PE Engineering-45: Materials of Engineering
Linear Elastic DeformationLinear Elastic Deformation Consider a Tension Test With SMALL
loads; Plotting σ vs. ε Find
The Data Plots as a Line Through the Origin• Thus σ ε
– The Constant of Proportionality is the Slope, E
E is the “Modulus of Elasticity”, or “Young’s Modulus”• Linear Elastic Materials are said to follow
Hooke’s (spring) Law
F
Fsimple tension test
Linear- elastic
1E
E
[email protected] • ENGR-45_Lec-14_Metal_MechProp-1.ppt14
Bruce Mayer, PE Engineering-45: Materials of Engineering
Linear Elastic DeformationLinear Elastic Deformation During a Pull-Test the Material
CONTRACTS Laterally,εL, as it Extends Longitudinally, ε. Plotting
This Data Also Plotsas a Line• Thus εL ε
– The Constant of Proportionality is the Slope,
is “Poisson’s Ratio” as Defined by
F
Fsimple tension test
L
L
1
[email protected] • ENGR-45_Lec-14_Metal_MechProp-1.ppt15
Bruce Mayer, PE Engineering-45: Materials of Engineering
Shear ModulusShear Modulus Data From
vs. ShearStress Test
• Where– G Modulus of
Rigidity (Shear Modulus)
G Leads to Hooke’s
Law in Pure ShearT
HIN
Wal
led
Cyl
ind
er
http://www.efunda.com/materials/common_matl/Common_Matl.cfm?MatlPhase=Solid&MatlProp=Mechanical#Mechanical
1G
RaLa arctanarctan
[email protected] • ENGR-45_Lec-14_Metal_MechProp-1.ppt16
Bruce Mayer, PE Engineering-45: Materials of Engineering
Bulk ModulusBulk Modulus Data From
P vs. VTests
Leads to Hooke’s Law in Pure HydroStatic Compression
Pressure Test:
Init. vol =Vo. Vol chg. =
V
P
P P
P
P
V
1-K Vo
OV
VK P
• Where– K Modulus of
Compression (Bulk Modulus) in GPa or Mpsi
[email protected] • ENGR-45_Lec-14_Metal_MechProp-1.ppt17
Bruce Mayer, PE Engineering-45: Materials of Engineering
Elastic (Hooke’s) RelationsElastic (Hooke’s) Relations Uniaxial Tension Isotropic Material
“Modulus Relations”Eε • Also Poisson’s Ratio 12EG
G Pure Shear
L
OV
VK P
All-Over Compression
213 EK
Steel Properties• E = 190-210 GPa• G = 75-80 GPa• K = 150-160 GPa = 0.27-0.3
[email protected] • ENGR-45_Lec-14_Metal_MechProp-1.ppt18
Bruce Mayer, PE Engineering-45: Materials of Engineering
Elastic Properties of MetalsElastic Properties of MetalsMetal
Young's ModulusE (Mpsi)
Shear modulus, G (Mpsi)
Bulk Modulus,K (Mpsi)
Poisson'sratio,
Aluminum 10.2 3.8 10.9 0.3Brass, 30 Zn 14.6 5.4 16.2 0.4Chromium 40.5 16.7 23.2 0.2
Copper 18.8 7.0 20.0 0.3Iron (soft) 30.7 11.8 24.6 0.3Iron (cast) 22.1 8.7 15.9 0.3
Lead 2.3 0.8 6.6 0.4Magnesium 6.5 2.5 5.2 0.3Molybdenum 47.1 18.2 37.9 0.3Nickel (soft) 28.9 11.0 25.7 0.3Nickel (hard) 31.8 12.2 27.2 0.3
Nickel-silver, 55CU-18Ni-27Zn 19.2 5.0 19.1 0.3Niobium 15.2 5.4 24.7 0.4
Silver 12.0 4.4 15.0 0.4Steel, mild 30.7 11.9 24.5 0.3
Steel, 0.75 C 30.5 11.8 24.5 0.3Steel, 0.75 C, hardened 29.2 11.3 23.9 0.3
Steel, tool 30.7 11.9 24.0 0.3Steel, tool, hardened 29.5 11.4 24.0 0.3
Steel, stainless, 2Ni-18Cr 31.2 12.2 24.1 0.3Tantalum 26.9 10.0 28.5 0.3
Tin 7.2 2.7 8.4 0.4Titanium 17.4 6.6 15.7 0.4Tungsten 59.6 23.3 45.1 0.3Vanadium 18.5 6.8 22.9 0.4
Zinc 15.2 6.1 10.1 0.2
[email protected] • ENGR-45_Lec-14_Metal_MechProp-1.ppt19
Bruce Mayer, PE Engineering-45: Materials of Engineering
MetalsAlloys
GraphiteCeramicsSemicond
PolymersComposites
/fibers
E(GPa)
Based on data in Table B2,Callister 7e.Composite data based onreinforced epoxy with 60 vol%of alignedcarbon (CFRE),aramid (AFRE), orglass (GFRE)fibers.
Young’s Moduli: ComparisonYoung’s Moduli: Comparison
109 Pa
0.2
8
0.6
1
Magnesium,Aluminum
Platinum
Silver, Gold
Tantalum
Zinc, Ti
Steel, NiMolybdenum
Graphite
Si crystal
Glass -soda
Concrete
Si nitrideAl oxide
PC
Wood( grain)
AFRE( fibers) *
CFRE*
GFRE*
Glass fibers only
Carbon fibers only
Aramid fibers only
Epoxy only
0.4
0.8
2
4
6
10
20
40
6080
100
200
600800
10001200
400
Tin
Cu alloys
Tungsten
<100>
<111>
Si carbide
Diamond
PTFE
HDPE
LDPE
PP
Polyester
PSPET
CFRE( fibers) *
GFRE( fibers)*
GFRE(|| fibers)*
AFRE(|| fibers)*
CFRE(|| fibers)*
Eceramics > Emetals >> Epolymers
[email protected] • ENGR-45_Lec-14_Metal_MechProp-1.ppt20
Bruce Mayer, PE Engineering-45: Materials of Engineering
Temperature EffectsTemperature Effects Affect of Temperature on an Aluminum Alloy
In General for Increasing T• E↓
L↑ at Fracture
↓ at Fracture
[email protected] • ENGR-45_Lec-14_Metal_MechProp-1.ppt21
Bruce Mayer, PE Engineering-45: Materials of Engineering
Some Linear Elastic RelationsSome Linear Elastic Relations UniAxial Tension Simple Torsion, Solid
CylinderM=moment =angle of twist
2ro
Lo
– Material, geometric, and loading parameters contribute to deflection
– Larger elastic moduli minimize elastic deflection
F
Ao/2
L/2
Lowo
FLo
EAo
L
Fw o
EAo
2MLo
ro4G
[email protected] • ENGR-45_Lec-14_Metal_MechProp-1.ppt22
Bruce Mayer, PE Engineering-45: Materials of Engineering
WhiteBoard WorkWhiteBoard Work 6.66 kN
6.66 kN
Cu380 mm
d
Consider this Situation: Given for Cu
• E = 110 GPa (16 Mpsi)
y = 240 MPa (35 ksi)
Find PreLoad/PreStrain Diameter, d, for a PostLoad/PostStrain Axial Extension δ = 0.5 mm