Strength of Materials

Strength of Materials

"THE ESTABLISHED LEADER IN EE REVIEW"

MULTIVECTOR Review and Training Center Rm. 867, Ground Floor, Isabel Bldg. F. Cayco comer Espafia Sts. Sampaloc, Manila Tel. No. 7317423

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MUL T.IVECTOR REVIEW AND TRAINING CENTER STRENGTH CHt~TERIALS STRENGTH OF MATERIALS - is a measure of its ability to resist the application ofthe load required during the service of the structure of the machine without fracture, collapse or undue distortion. Stress- is the mechanical force on energy that causes or produces deformation or fracture in the material. -defined as resistance to external forces and it is measured in terms of the force exerted per unit of area. 1- Simple Stresses: I.

Axial Stress: a. h.

Tensile stress Compressive stress

Formula: p

S=A

where: A .l P S =stress P = load or total external load . A =stressed area 2.

Shearing Stress:

Formula: Ss ==

~~

projected area

where: As// Ps . 3.

Bearing Stress

Formula:

p

Sb=~ where Ab is the projected area

II Factor of Safety (FS)- is the ratio of ultimate stress to allowable stress.

_ Greatest .stress of'\ FS =·Ultimate stress ~ material can withstand Allowable stress , without rapture Note FS > I Thin-Walled Pressure Vessel:

I Cylindrical Shape

D

'Workin~·stress or safe working stress

MULTIVECTOR REVIEW AND TRAINING CENTER STRENGTH OF MATEl~lALS F

a) Circumferential Stress (Sc)- stress at the side.

p

p

A

A

F = Bursting force

P = Resisting force

L:Fv = 0 2P=F 2 Astress · .Sc = pA 2 (LX t) (Sc) = p (D XL)

_.212_

Sc- 2t a.

Longitudinal Stress (SL)- stress at the end:

~,..

p

,.

1\

'

\

II

__ /

II

I

'-..:......---_.... ~--------' ',_f'~.:-: t /

. . . . . . . . . . . . . . . . . . . . ..

p = C0h p = hydrostatic pressure or gauge pressure in the tank Inner Diameter D = diameter · t = thickness C0 =density of the fluid h = elevation head where:

Asu:ess · SL = P A n D t SL = p ~ D 2

.

4

SL= pD 4t Note:

~

I\ \

l::FH = 0 P=F

-~---------------

t .. , ,/,/-r'::,~",~,.-------- ~ 1 1 D I I :-.:: \ i i I F --'f.l',-.1'+---.t--

SL = ~ Sc

II Spherical Shape:

n

?

F= p-D4

L:F = 0 P=F nDtS = p~D 2

4

s = J2.Q_ 4t

P = n Dt S

MULTIVECTOR REVIEVV ..1!\.ND TRAINING CENTER

STRENGTH OF .MATERIALS Rotating Steel Ring

F= mo/r

IFH=O

2P"" F 2AS =

where:

molr

F = bursting force/ centrifugal force P =resisting 'force

m =.mass of one-half of the ring A= cross-sectional area of the ring V = volume of one-half of the ring p = mass density

r=l!£_ 11:

l'c "'' mean radius co = angular velocity; rad/sec v = peripheral velocity of the ring

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