Mechanical Engineering Answers

Listed below is a combination of stresses acting at a point and referred to axes x and y in an elastic material. Using Mohr’s circle of stress determine the principal stresses at the point and their directions for each combination. 

i) sigma x=-60 N/mm^2, sigma y=-36N/mm^2, shear stress (xy) =5N/mm^2

ii) sigma x=30 N/mm^2, sigma y=-50N/mm^2, shear stress (xy) =30N/mm^2

At a particular point in a structural member a two dimensional stress system exists where sigma x=60N/mm^2 sigma y=-40N/mm^2 and shear stress (xy) =50N/mm^2 if young's modulus =200000N/mm^2 and poisson's ratio =0.3 calculate the direct strain in the x and y directions and the shear strain at the point.

Direct stresses of 120 N/mm^2 (tension) and 90 N/mm^2 (compression) are applied at a particular point in an elastic material on two mutually perpendicular planes the principal

stress in the material is limited to 100 N/mm^2(tension) calculate the allowable value of shear stress at the point on the given planes determine also the value of the other principal stress and the maximum value of shear stress at the point using Mohr's circle

A member ABCD is subjected to point loads P1,P2,P3, and P4 calculate the force P3 necessary for equilibrium if P1, = 120 kN, P2, = 220 kN and P4, = 160 kN. Determine also the. net change in the length of the member. Take E = 200 GN/m²

Air at 30°C flows over a plate at a velocity of 2 m/s the plate is 2m long and 1.5m wide. calculate the following Hydrodynamic and thermial boundary layer thickness at the trailing edge of the plate, Total drag force, Total mass flow rate through the boundary layer between x40 cm, x=85 cm.

The lifetime of 225 light bulbs is measured and the sample mean and sample variance are found to be 223 hr and 100 hr2 , respectively. (a) Find a 95% confidence interval for the mean lifetime. (b) Find a 95% confidence interval for the variance of the lifetime.

A member ABCD is subjected to point loads P1,P2,P3, and P4 calculate the force P3 necessary for equilibrium if P1, = 120 kN, P2, = 220 kN and P4, = 160 kN. Determine also the. net change in the length of the member. Take E = 200 GN/m². Calculate 40 mm x 40 mm 25 mm x 25 mm 30 mm x 30 mm A в P2 + 0.75 cm + im 1.2 m-

AD is string hung from a horizontal ceiling at A and D. A weight of 75kN is hung from point B.

Determine the magnitude of weight that should be hung from point C such that the portion BC of the string is horizontal. Point B is 0.6cm from A and point C is 0.35cm from D as shown below. Also calculate the tension in the various portion AB,BC and CD of the string

Direct stresses of 120 N/mm^2 (tension) and 90 N/mm^2 (compression) are applied at a particular point in an elastic material on two mutually perpendicular planes the principal

stress in the material is limited to 100 N/mm^2(tension) calculate the allowable value of shear stress at the point on the given planes determine also the value of the other principal stress and the maximum value of shear stress at the point using Mohr's circle

A single-stage impulse turbine rotor has a mean blade ring diameter of 500 mm and rotates at a speed of 10,000 rpm. The nozzle angle is 20° and the steam leaves the nozzles with a velocity of 900 m/s. The blades are equiangular and the blade friction factor is 0.85. Construct the velocity diagrams for the blades and determine the inlet angle of the blades for shockless entry of steam. Determine  (a) the diagram power for a steam flow of 750 kg/h,  (b) the diagram efficiency,  (c) the axial thrust, and (d) the loss of kinetic energy due to friction.