At a point in a stressed body, the principal stresses
are 100 MN/m2

(tensile) and 60 MN/m2

(compressive). Determine the normal stress and

the shear stress on a plane inclined at 50degree

counter clockwise to the axis

of minor principal stress. Also, calculate the maximum shear stress
at the

point and draw the Mohr’s stress circle to verify the
answers.

If the yield strength and Poisson’s ratio of the material in the
above case

is 240 MPa and 0.3 respectively, check whether the failure will
occur or

not according to (a) Maximum principal strain theory and (b)
Maximum

shear strain energy per unit volume theory. If failure does not
occur,

calculate the Factor of Safety.

In: Mechanical Engineering

An air-standard dual cycle has a compression ratio of 14. At the
beginning of compression, *p*_{1} = 14.5
lbf/in.^{2}, *V*_{1} = 0.5 ft^{3},
and *T*_{1} = 50°F. The pressure doubles during the
constant-volume heat addition process.

For a maximum cycle temperature of 3500°R, determine:

(a) the heat addition to the cycle, in Btu.

(b) the net work of the cycle, in Btu.

(c) the percent thermal efficiency.

(d) the mean effective pressure, in lbf/in.^{2}

In: Mechanical Engineering

Question 1

(a) For the nucleation process, explain the difference between homogeneous and heterogeneous nucleation. Why heterogeneous nucleation is more common than

homogeneous nucleation.

(b) (i) Sketch and label the cross-section view of common
macrostructure of a metal ingot after solidification process.

(ii) If the molten metal is added with 2 wt% of grain refiner,
explain how the grain refiner changes the macrostructure of this
metal ingot.

(c) What is the difference between point defect and
line defect?

(d) Briefly explain why vacancies and
self-interstitials are considered as the crystal defects?

In: Mechanical Engineering

A floating ball has a density (P») of 600 kg/m' and has a
radius (R) of 0.055 m. The equation that

gives the depth (x) to which the ball is submerged under water
with a density (Pw) of 1000 kg/m

is given by:4

4/3*pi*R^3*pb*g=pi*x^2(R_x/3)*Pw*g

where the gravitational acceleration g = 9.81 m/s.

R

a) Use the false-position method to find the depth x to

which the ball is submerged under water within an

interval [0, 0.1]? Conduct three iterations only and
find

the absolute relative approximate error at the end of

each iteration?

Water

Note: Summarize your results in one table and show one
complete sample of calculations for one

iteration only.

b) If you would change the previous method to an open domain
method to find the depth x; what

method would you select? Explain briefly (in English and
without calculations), what would

you do and how would you do the computations.

In: Mechanical Engineering

Name and explain three processes that done after printing the design to have it in its final state?

Do all technologies need those processes, which one needs minor after processing?

3D printing

In: Mechanical Engineering

Saturated liquid refrigerant R-134a is throttled from 900 to 90 kPa at a rate of 0.32 kg/s. What is the rate of entropy generation for this throttling process? kW/K

In: Mechanical Engineering

Thirty-six grams of air in a piston–cylinder assembly undergo a
Stirling cycle with a compression ratio of 7.5. At the beginning of
the isothermal compression, the pressure and volume are 1 bar and
0.03 m^{3}, respectively. The temperature during the
isothermal expansion is 1200 K.

Assuming the ideal gas model and ignoring kinetic and potential
energy effects, determine:

(a) the net work, in kJ.

(b) the percent thermal efficiency.

(c) the mean effective pressure, in bar.

In: Mechanical Engineering

A well insulated nozzle with a 0.005 m2 inlet cross section at 15 MPa and 673 K water vapor enters at a speed of 25 m / s. The pressure of the steam-liquid mixture, whose quality is 80% at the nozzle outlet, was measured as 4.688 MPa. Work done on the nozzle is neglected. So,

a) Speed at the nozzle outlet (m / s)

b) Mass flow (kg / s),

c) Calculate the exit cross section of the nozzle (m2)

In: Mechanical Engineering

We place a 3.4 cm-tall circular object in front of an unknown lens and observe a 2.4 cm-tall circular image on a screen. We move the object either towards or away from the lens. The circular image moves 2.2 cm either towards or away from the lens; the new image is 5.7 cm tall.

a) Is the lens converging or diverging? Do you move the object towards or away from the lens? Does the image move towards or away from the lens? Explain!

b) Use ray tracing to find the focal length of the lens and the location of the lens! use empty next page!

c) Use ray tracing to find the two locations of the object that produce the two images. How much do we move the object?

In: Mechanical Engineering

A 4 cylinder 4 stroke 2.3 L diesel engine with bore = 12.4 cm
and stroke =11 cm. the crank radius is 6.2 cm and with a connecting
rod length 15 cm. the compression ratio of the engine is 20 and the
combustion efficiency is 97.3 %. If the average speed of the car
over the running life of the engine is 56 km/h and the total
traveled distance of the engine is 250000 km.
**note:** use the engine speed as 2300 rpm whenever
needed, mechanical efficiency is 73 %, indicated work produced from
each cycle each cylinder is 1400J, and assume that the injection
started 10 degrees bTDC and ends at 25 crank angle degree aTDC.

Determine:

- The volume of the BDC.
- The amount of the fuel that didn’t burned in the combustion chamber .
- The rate of the air flow to the engine if the volumetric efficiency is 70 %.
- The number of the exhaust strokes that have been happened during the engine life in one cylinder.
- Indicated mean effective pressure.
- The torque produced from the engine.
- The time duration for the injection process.
- The position of the piston at the end of the injection period.
- The volume of the combustion chamber at the moment of the injection process.
- If the mass floe rate of the fuel used if A/F is 19.3 kgair/kgfuel.
- The specific power of the engine.
- Based on the dimensions of the bore and the stroke, is this engine square engine or over or under square one?

In: Mechanical Engineering

The ceiling of an ice skating rink should have a high
reflectivity to avoid condensation on the ceiling . If condensation
forms on the ceiling , water may drip ca ice . The rink has a
diameter of 50m and a height of 12m . The temperature of the ice
and walls are -5 ° C and 15 ° C respectively . The air in the rink
is also at 15 ° C Neglect the convective losses to the outside air
. If the ceiling is a diffese - gray surface and the ice and walls
can be approximated as black bodies , perform an energy balance on
the ceiling to calculate the ceiling temperature . If the relative
humidity of the rink air is 70 % and the dew point is 9c , will
condensation occur if a coating is added that provides an
emissivity of 0.05 ?

In: Mechanical Engineering

Air enters the turbine of a gas turbine at 1400 kPa, 1400 K, and
expands to 100 kPa in two stages. Between the stages, the air is
reheated at a constant pressure of 350 kPa to 1400 K. The expansion
through each turbine stage is isentropic.

Determine:

(b) the heat transfer for the reheat process, in kJ/kg of air
flowing.

(c) the increase in net work as compared to a single stage of
expansion with no reheat.

In: Mechanical Engineering

hi please elaborate axial flow pumps working principle with labelled and the flow image , application and limitation .

In: Mechanical Engineering

Hello! In Ansys Fluent, how can I calculate the molar concentration (kmol/m^3) of a species and molar fraction (dimensionless) of a species in fluent after I put an exact amount of the mass (kg) of a species at a boundary? Thank you, I will thumb you up!

In: Mechanical Engineering

Make * a mindmap* that contain:

a- Relationship between Mechanical Energy Equation and internal flow analysis.

b- Flow regimes - Search on the turbulent, laminar and transitional flow regimes. Describes them and give example when/where they occurs.

c- Region in pipe flow - Search on hydrodynamic entrance length, boundary layer region/viscous flow region, hydrodynamically developing region and hydrodynamically fully developed region. Describes them and show how to calculate them.

In: Mechanical Engineering