Explain the differences between solidification cracking, HAZ cracking, hydrogen induced cracking, and lamellar cracking.

Why is a wide, shallow bead preferred over a narrow, deep weld bead?  

Why do some cast irons of the same type have a ferritic matrix and others a pearlitic matrix?

Why are white cast irons considered unweldable?

Problem 4. Explain to high school level students about streamlines, streaklines, and pathlines. Please explain by inserting a figure if necessary.

問題４．流線、流脈線、流跡線について高校生にわかるように説明しなさい。必要に応じて挿絵(Figure)を入れて説明しなさい。

A rigid tank A is connected to a spherical and elastic balloon B. Each contains air at an ambient temperature of 25 ° C. The volume of tank A is 0.1 m³ and the initial absolute pressure is
300 kPa. The initial diameter of the balloon is 0.5 m and the internal absolute pressure is 100 kPa. The tap connecting A and B is opened and left open. It can be assumed that the pressure inside the balloon is directly proportional to the diameter of the balloon and that the final air temperature therein is uniform at 25 ° C. Determine the final pressure in the system and the final volume of the balloon.

ans: Pfinal = 137 kPa Vfinal= 0,167 m³

7. Draw one stress strain diagram for ductile material and indicate the elastic, plastic region, toughness and resilience?

-Explain the mechanism of necking in details?

9. What is the unite for stress and strain?

10. What are the mechanical requirements to design a material for high temperature applications?

3.- In an industrial process, a concentric tube exchanger is used to cool 1800 Kg / hr of ammonia from 80 ° C to 35 ° C circulating through the annular space, with 1485 Kg / hr of water entering the concentric tube at 25 ° C. The water leaving the exchanger is sent to a mixing tank with agitation, which is fed by another stream of water at 15 ° C in order to reduce its temperature to 25 ° C and reuse it in the heat exchanger. Considering that the specific heat of ammonia is a function of temperature, how many Kg / hr should water be supplied to the mixing tank at 15 ° C?

A power plant operates on a regenerative vapor power cycle with one open feedwater heater. Steam enters the first turbine stage at 12 MPa, 560°C and expands to 1 MPa, where some of the steam is extracted and diverted to the open feedwater heater operating at 1 MPa. The remaining steam expands through the second turbine stage to the condenser pressure of 28 kPa. Saturated liquid exits the open feedwater heater at 1 MPa. The net power output for the cycle is 330 MW. Assume that both turbine stages and both pumps have an isentropic efficiency of 75%.

Determine:

(a) the percent cycle thermal efficiency.

(b) the mass flow rate into the first turbine stage, in kg/s.

(c) the rate of entropy production in the open feedwater heater, in kW/K.

Determine the specific internal energy (in kJ/kg) of water at 400C and 20 MPa.

(Please show how units cancel)!

Manual Labor in Production Systems Is there a place for manual labor in the modern production system?

 Answer: YES

 Two aspects

: 1. Manual labor in factory operations

2. Labor in manufacturing support systems

i want solve the 2 question as presentation

thanks

Question 2:
“The RMS Titanic was an Olympic-class passenger liner, launched for the
first time in 31 May 1911. The ship’s steel was “probably the best plain
carbon ship plate of the time”. Nevertheless, shortly before midnight on 14
April 1912, four days into the ship’s maiden voyage, Titanic hit an iceberg.
The impact caused the hull to fracture and water poured into the ship, sinking
it two hours and forty minutes later. Of the 2223 people on board, only 706
survived. Most of the victims died of hypothermia in the icy -2°C Atlantic
waters between Southhampton and New York, the destination, where the
ship sank. There are many factors that contributed to the sinking of the ship;
one of the primary reasons being metallurgy of the ship’s hull.”

Explain why even if engineers had tested the steel hull’s material properties
at room temperature, they still would not have predicted failure when taking
the impact of the iceberg in the icy Atlantic waters into account. Also,
describe how the steel should have been tested.

In Case of Gas power plant, Clearly Identify the at least 12 Important parts. Explain the kind of fuel is used to run the gas power plant. Compare between the Gas power plant and Diesel power plant

Discuss how the fatigue resistance of a part or material can be improved.

Its for 5 marks so please no short answers.

Consider an automobile engine which operates on the ideal Otto cycle. In this engine, air is compressed with a compression ratio of 10. At the beginning of the compression process, air is at 105 kPa and 17oC, and in the combustion process 640 kJ/kg of heat is added to air. Taking into account the variation of specific heats with temperature, determine (a) the pressure and temperature at the end of the heat-addition (combustion) process, (b) the net work output, (c) the thermal efficiency of the engine, and show the cycle on a P-ν diagram.

Consider a diffuser in which air flows steadily. At the inlet of the diffuser the pressure, the temperature and the velocity of the air are 100 kPa, 110oC and 175 m/s, respectively. At the exit of the diffuser the pressure, the velocity of the gas and the area of the diffuser are 110 kPa, 15 m/s and 0.1 m2 , respectively. Accounting for an heat loss of 3 kJ/kg from the diffuser to the surroundings at 100 kPa and 25oC and assuming constant specific heats, determine (a) the exit temperature, (b) the rate of exergy change and (c) the second-law efficiency of the diffuser where ηII, diffuser = exergy output exergy input .

make a scheme or illustration of the precipitation hardening process for aluminum alloys and explain each step

Vibrations Question in Mechanical Engineering:

Vibrating System

Stability Question

Describe in as much detail as possible what is meant by a stable vibrating system and state the condition which must be satisfied to achieve stability.