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1.3 Stress - KOCWcontents.kocw.net/KOCW/document/2015/hanyang/hanseog... · 2016-09-09 · F dydz dydz dxdz dxdz dydz dxdz M dydz dx dxdz dy dx τ xy τ xz σ x σ y’ τy’x τ

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Page 1: 1.3 Stress - KOCWcontents.kocw.net/KOCW/document/2015/hanyang/hanseog... · 2016-09-09 · F dydz dydz dxdz dxdz dydz dxdz M dydz dx dxdz dy dx τ xy τ xz σ x σ y’ τy’x τ
Page 2: 1.3 Stress - KOCWcontents.kocw.net/KOCW/document/2015/hanyang/hanseog... · 2016-09-09 · F dydz dydz dxdz dxdz dydz dxdz M dydz dx dxdz dy dx τ xy τ xz σ x σ y’ τy’x τ
Page 3: 1.3 Stress - KOCWcontents.kocw.net/KOCW/document/2015/hanyang/hanseog... · 2016-09-09 · F dydz dydz dxdz dxdz dydz dxdz M dydz dx dxdz dy dx τ xy τ xz σ x σ y’ τy’x τ

1.3 Stress

Copyright © 2011 Pearson Education South Asia Pte Ltd

0lim

x

x xx A

x x

F dFA dA

0lim

x

y yxy A

x x

F dFA dA

0lim

x

z zxz A

x x

F dFA dA

Page 4: 1.3 Stress - KOCWcontents.kocw.net/KOCW/document/2015/hanyang/hanseog... · 2016-09-09 · F dydz dydz dxdz dxdz dydz dxdz M dydz dx dxdz dy dx τ xy τ xz σ x σ y’ τy’x τ

1.3 Stress

Copyright © 2011 Pearson Education South Asia Pte Ltd

0lim

y

y yy A

y y

F dFA dA

0lim

y

z zyz A

y y

F dFA dA

0lim

y

x xyx A

y y

F dFA dA

Page 5: 1.3 Stress - KOCWcontents.kocw.net/KOCW/document/2015/hanyang/hanseog... · 2016-09-09 · F dydz dydz dxdz dxdz dydz dxdz M dydz dx dxdz dy dx τ xy τ xz σ x σ y’ τy’x τ

1.3 Stress

Copyright © 2011 Pearson Education South Asia Pte Ltd

0lim

z

z zz A

z z

F dFA dA

0lim

z

x xzx A

z z

F dFA dA

0lim

z

y yzy A

z z

F dFA dA

i jdirectionof force

direction of a normal to the plane

Page 6: 1.3 Stress - KOCWcontents.kocw.net/KOCW/document/2015/hanyang/hanseog... · 2016-09-09 · F dydz dydz dxdz dxdz dydz dxdz M dydz dx dxdz dy dx τ xy τ xz σ x σ y’ τy’x τ

Therefore, we can express the state of stress at a point

For 2-D case

* uniaxial stress, biaxial stress, triaxial stress, pure shear

1.3 Stress

Copyright © 2011 Pearson Education South Asia Pte Ltd

[ ]

x xy xz

yx y yz

zx zy z

[ ]

x xy

yx y

-x plane+x plane

Page 7: 1.3 Stress - KOCWcontents.kocw.net/KOCW/document/2015/hanyang/hanseog... · 2016-09-09 · F dydz dydz dxdz dxdz dydz dxdz M dydz dx dxdz dy dx τ xy τ xz σ x σ y’ τy’x τ

Copyright © 2011 Pearson Education South Asia Pte Ltd

' '

' '

' '

00

( ) ( ) 0

,

00

x

x x yx y x

x x yx y x

x x yx y x

z

xy yx

xy yx

Fdydz dydz dxdz dxdz

dydz dxdz

Mdydz dx dxdz dy

dx

τxy

τxzσx

σy’

τy’xτy’z

σx’

τx’z

dz

τx’y

dy

σz

σy

τyx

σx’

σyτyx

τxy

σx

σy’

τx’y

τy’x

dx

dy

Page 8: 1.3 Stress - KOCWcontents.kocw.net/KOCW/document/2015/hanyang/hanseog... · 2016-09-09 · F dydz dydz dxdz dxdz dydz dxdz M dydz dx dxdz dy dx τ xy τ xz σ x σ y’ τy’x τ

Copyright © 2011 Pearson Education South Asia Pte Ltd

σy

σzτzy

τyz

σz’

τy’z

τz’y

σy’

dy

dz

' '

' '

' '

0

0

( ) ( ) 0

,

00

y

y y zy z x

y y zy z y

y y zy z y

x

yz zy

yz zy

F

dxdz dxdz dxdy dxdy

dxdz dxdy

Mdxdz dy dxdy dz

' ' ', , ,

, , x x y y z z

xy yx yz zy xz zx

Therefore

Page 9: 1.3 Stress - KOCWcontents.kocw.net/KOCW/document/2015/hanyang/hanseog... · 2016-09-09 · F dydz dydz dxdz dxdz dydz dxdz M dydz dx dxdz dy dx τ xy τ xz σ x σ y’ τy’x τ

Copyright © 2011 Pearson Education South Asia Pte Ltd

1.4 Average Normal Stress

for small area avgF AA

avgdF dA A P

avgPA

dFdA

Page 10: 1.3 Stress - KOCWcontents.kocw.net/KOCW/document/2015/hanyang/hanseog... · 2016-09-09 · F dydz dydz dxdz dxdz dydz dxdz M dydz dx dxdz dy dx τ xy τ xz σ x σ y’ τy’x τ

Copyright © 2011 Pearson Education South Asia Pte Ltd

z

x

y

oy

zσx

0

0

0, centroid of cross section

y x

y x avg

y avg avg

z x

z avg avg

avg

dM z dA

M z dA z dA

M zdA zA

dM y dA

M y dA ydA

yA

y z