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29-Sep-10 SJEC4SimpleStresses ١

Engineering MechanicsIII

(Stress Analysis)

MANF231

Simple Stresses

Part C4

29-Sep-10 SJEC4SimpleStresses ٢

Exercise C15

The steel tie bar shown is tobe designed to carry atensile force P=120kN whenbolted between doublebrackets at A and B. The barwill be fabricated from a20mm thick plate. For steel,the maximum allowablestresses are σ=175MPa,shear stress=100MPa andσb=175MPa. Find thediameter d of the bolt, thedimension b at each end ofthe bar and the dimension hof the bar.

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Exercise C15Diameter of Bolt

Shear Stress

Bearing Stress

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Exercise C15

Dimension b

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Exercise C15

Dimension h

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Exercise C16

Two forces are applied to the bracket

BCD as shown.1. Knowing that the control rod AB is

to be made of a steel having an

ultimate normal stress of 600MPa,

determine the diameter of the rod

for which the factor of safety withrespect to failure will be 3.3.

2. The pin at C is to be made of a steel

having an ultimate shearing stress

of 350MPa. Determine the diameter

of the pin C for which the factor ofsafety with respect to shear will

also be 3.3.

3. Determine the required thickness of

the bracket supports at C knowing

that the allowable bearing stress ofthe steel used is 300MPa.

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Exercise C16

Free body diagram

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Exercise C16

Control rod AB

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Exercise C16

Shear in pin C

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Exercise C16

Bearing at C

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Exercise C17

The rigid beam BCD is attached bybolts to a control rod at B, to ahydraulic cylinder at C and to a fixedsupport at D. The diameters of thebolts used are dB=dD=10mm,dC=12mm. Each bolt acts in doubleshear and is made from a steel forwhich the ultimate shearing stress=280MPa. The control rod AB has adiameter dA=11mm and is made of asteel for which the ultimate tensilestress =420MPa. If the minimumfactor of safety is to be 3 for theentire unit, determine the largestupward force which may be appliedby the hydraulic cylinder at C.

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Exercise C17

Free body diagram

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Exercise C17

Control rod AB

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Exercise C17

Bolt at B

Bolt at D

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Exercise C17

Bolt at C

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The horizontal link BC is 6 mm thick and is made of a

steel with a 450 MPa

ultimate strength in

tension.

What should be the width w of the link if the

structure shown is to be

designed to support a

load P = 32 kN with a

factor of safety = 3 ?

Exercise C18