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1.

ROTATING SHAFT

Given A rotating shaft simply supported in ball bearings at A and D and loaded by a non rotating force F of 6.8 kN

Problem Using ASTM “minimum” strengths, estimate the life of the part.

2.

CREEP-TIME CURVE

Problem Define ‘Creep’, draw the creep-time curve and discuss each region on it.

3.

COLUMN ANALYSIS

Given A column has both ends pinned and has a length of 32in. It is made of AISI 1040 HR steel and has a circular shape with a diameter of 0.75in.

Problem Determine the critical load.

4.

FATIGUE STRENGTH

Problem

Estimate the fatigue strength of a rotating-beam specimen made of AISI 1020 hot-rolled steel corresponding to a life of 12.5 kilocycles of stress reversal. Also, estimate the life of the specimen corresponding to stress amplitude of 36 kpsi. The known properties are Sut = 66.2 kpsi,

σ0 = 115 kpsi, m = 0.22, and εf = 0.90.

SHEET2: FATIGUE, CREEP & BUCKLING

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5.

HYDRAULIC CYLINDER COLUMN ANALYSIS

Given

The hydraulic cylinder shown in the figure has a 3-in bore and is to operate at a pressure of 800 psi. With the clevis mount shown, the piston rod should be sized as a column with both ends rounded for any plane of buckling. The rod is to be made of forged AISI 1030 steel without further heat treatment.

Problem

a) Use a design factor nd = 3 and select a preferred size for the rod diameter if the column length is 60 in.

b) Repeat part (a) but for a column length of 18 in. c) What factor of safety actually results for each of the cases above?

6.

VEHICULAR JACK COLUMN ANALYSIS

Given

The figure shows a schematic drawing of a vehicular jack that is to be designed to support a maximum mass of 400 kg based on the use of a design factor nd = 2.50. The opposite-handed threads on the two ends of the screw

are cut to allow the link angle θ to vary from 15 to 70◦. The links are to be machined from AISI 1020 hot-rolled steel bars with minimum yield strength of 380 MPa. Each of the four links is to consist of two bars, one on each side of the central bearings. The bars are to be 300 mm long and have a bar width of 25 mm. The pinned ends are to be designed to secure an end-condition constant of at least C = 1.4 for out-of-plane buckling.

Problem Find a suitable preferred thickness and the resulting factor of safety for this thickness.

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Fatigue strength fraction, f,

Parameters for Surface Modification

Effect of Operating Temperature on the Tensile Strength of Steel.* (ST = tensile strength at

operating temperature; SRT = tensile strength at room temperature; 0.099 ≤σ≤ 0.110)

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Reliability Factors ke Corresponding to 8 % Standard Deviation of the Endurance Limit

Notch-sensitivity charts for steels and UNS A92024-T wrought aluminum alloys subjected to

reversed bending or reversed axial loads. For larger notch radii, use the values of q corresponding to the r = 0.16-in (4-mm) ordinate.

Notch-sensitivity curves for materials in reversed torsion. For larger notch radii, use the

values of qshear corresponding to r = 0.16 in (4 mm).

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Round shaft with shoulder fillet in bending. σ0 = Mc/I, where c = d/2 and I = πd4/64.

(a) Both ends rounded or pivoted; (b) both ends fixed; (c) one end free and one end fixed;

(d) one end rounded and pivoted, and one end fixed.