文档介绍：സޙէذူדԛࡔჃέcสྭ
സޙէذރԅέئᅀࣸག 9-1­ ¢
സޙէذރၕᅀૅᅧನԅέ 9-2­ ¢
സޙէذރԅௗέॣ 9-3­ ¢
¢ ­9-4 ߅ӦбࡁՇูඕ
സޙէذူדԛࡔჃέcสྭ
¢ ᵘӊথ⫳ᎹЁ᠔ϡᆍ䆌ⱘ䖛বᔶ⿄Ў߮ᑺ
ϡ䎇DŽ
Ўњֱ䆕ᵘӊᅝܼǃℷᐌᎹˈᖙ乏ᇚ݊ᔍᗻব¢
ᔶ䰤ࠊϔᅮ㣗ೈПݙDŽᖙ乏ⷨおᵘӊⱘবᔶ
ԡ⿏DŽ
¢ ⷨおᴚӊবᔶԡ⿏ˈϔᮍ䴶ᰃЎњߚᵤᴚӊⱘ
߮ᑺ䯂乬ˈϔᮍ䴶ᰃЎњ∖㾷䍙䴭ᅮ䯂乬DŽ
സޙէذރԅέئc9-1 ᅀࣸག
¢ Ⳉᴚ䕈ᢝय़⫼ϟˈᴚ⊓䕈㒓ᮍⱘবᔶ
⿄Ў䕈বᔶ㒉বᔶ˗ൖⳈѢ䕈㒓ᮍⱘবᔶ⿄
Ў῾বᔶDŽ
¢ བ᠔⼎ⱘ䴶ᴚDŽ
¢ ld —ߚ߿㸼⼎ᴚӊবᔶࠡⱘ䭓ᑺⳈᕘ˗
¢ ߚ߿㸼⼎ᴚӊবᔶৢⱘ䭓ᑺⳈᕘDŽ
l1 d1—
F
P FP F
P 1 FP
d
1
d
d
d
l l1
l1 l
സޙէذރԅέئc9-1 ᅀࣸག
㒉বᔶ
¢ ∆l=l1-l
῾বᔶ
¢ ∆d=d1-d
¢ 㒉㒓ᑨবε= ∆l/ l
¢ ῾㒓ᑨবεĄ= ∆d / d
εĄ=ˉνε
F
P FP F
P 1 FP
d
1
d
d
d
l l1
l1 l
സޙէذރԅέئc9-1 ᅀࣸག
⬅˙˙
σ FN /A σ Eε
∆ l σ F F l EA˖⿄Ўᴚӊ
ε= = = N Ω∆ l = N
l E EA EA ⱘᢝय़߮ᑺDŽ
ᇍѢফϾ⫼ⱘᴚӊ
∆ F l
ƒ ƒ Ni i
l = ∆ li =
EAi
ᇍѢᡓফ䕈ߚᏗⱘᴚӊ
F (x)
∆ l = — N dx
l EA(x)
സޙէذރԅέئc9-1 ᅀࣸག
¢ ՟9-1 བ᠔⼎ⱘㄝⳈᴚˈ῾䴶䴶⿃A=500mm2ˈ
ᴤ᭭ⱘᔍᗻ䞣ˈE=200GPaˈ䆩∖ᴚӊᘏ㒉
বᔶDŽ
സޙէذރԅέئc9-1 ᅀࣸག
¢ 㾷˖
¢ ߎᴚⱘ䕈
∆ F l
⬅ l = ∆ƒ ∆ l = ƒ Ni i
i∆ EA
∆ i
l = l1 + l2 + ∆ l3
F l + F l + F l
= N1 1 N2 2 N3 3
EA
(6×103 )(1)- (2×103 )(2) + (3×103 )()
=
(2×109 )(500×10-6 )
= 65×10−6 m
= mm
സޙէذރԅέئc9-1 ᅀࣸག
¢ ՟9-2 a᠔⼎Ўϔ㾦ᶊDŽᴚ AB Ў䴶䩶ᴚˈⳈᕘ
ˈᴚ䭓˗ᴚЎℷᮍᔶ䴶ᴚᴚˈ
d=34mm l1= AC
䴶䖍䭓Ў˗䩶ⱘᔍᗻ䞣˗
a=170mm E1=210GPa
乎㒍ⱘᔍᗻ䞣˗ 0 ˗⚍໘⫼ⱘ䲚Ё
E2=10GPa θ=30 A
DŽ䆩∖㒧⚍ⱘԡ⿏DŽ
FP=40kN A
സޙէذރԅέئc9-1 ᅀࣸག
¢ 㾷˖
¢ ˄1˅ফߚᵤ˖প㒧⚍AЎⷨおᇍ䈵
ƒ Ω
Fy = 0, FN1 = FP / sinθ
ᢝ˅
= 2FP = 80 kN (
ƒ Ωय़˅
Fx = 0, FN2 = FN1 co∆sθ= kN (
∆
¢ ˄2˅বᔶ䅵ㅫ
FN1 l1 4FN1 l1 FN2 l2 FN2 l1 cosθ
l1 = = 2 l2 = = 2
E1 A1 E1π d E2 A2 E2 a
= ×10−3 m = ×10−3 m
= mm (Ԍ䭓˅= mm˄㓽ⷁ˅
സޙէذރԅέئc9-1 ᅀࣸག
¢ ˄3˅∖㒧⚍Aⱘԡ⿏
∆ l ∆ l
AA = AE + EA = 1 + 2
3 3 sinθ tanθ
mm mm
= + = mm
AA2 = ∆ l2 = mm
' 2 2
AA = (AA3 ) + (AA2 )
= ( mm)2 + ( mm)2 = mm