DieselShip's Online Content Library

Q7. Compare the destructive testing done on engineering materials with non-destructive testing done on engineering components. Briefly describe one destructive test and two non-destructive tests to illustrate your answer

Q2. (a) Materials used for hull and machinery are subject to stress and strain in service.

Define EACH of the following:

(i) types of stress;              (ii) types of strain

(b) Describe the tests that may be carried out on steel to be used for ships side plating.(5)

Q2. (a) Explain fatigue cracking, stating its causes and propagation. (8)

(b) Explain, how poor maintenance and engine overload may contribute to the risk of fatigue cracking of cylinder head holding studs. (8)

Q8. Explain why a material may fracture when stressed below its yield point. Give examples of components which might fracture in this way if suitable precautions are not taken. Explain how such fractures can be avoided with reference to the materials chosen, careful design and workmanship.

Q3. A. Explain the causes of the formation of mill scale on steel plate. Describe the preparation necessary before the application of conventional paints to the underwater surface of the hull; C. Describe a coating scheme for the underwater hull using conventional paints.

Q2.a) Define fatigue and fracture and specify the conditions under which it occurs.

b) Describe the different fracture modes and the mechanism of crack propagation in different fracture modes.

Q1. Discuss the causes of vibration and noise in main gearing and describe detrimental effects on machinery and operating personnel. How would you detect the source(s) of this vibration and how might it be reduced to tolerable limits?

Q6.a) Define the cause and effect of thermal stressing in cylinder heads, liners, and pistons.

Explain why thermal stressing is aggravated with an increase in the cylinder bore.

Explain how stress concentration and it's effects is relieved by maintenance and operational practices.

Q2. Describe in detail each of the following processes and give an example where each is likely to occur in marine engineering: State how in each case the initiation of the process is prevented or minimized. A. Corrosion fatigue; B. Stress corrosion; C. Creeping cracks; D. Casting cracks

Q9. (a) Describe the properties of each of the following alloys used in marine engineering, giving a practical example for which, each is suited:

(i) cupro-nickel

(ii) white metal

(iii) titanium.

b) Discuss the merits of EACH of the following alloys for use in the casting of large propellers:

(i) nickel aluminium bronze (ii) stainless steel.

c) Describe the tests that may be carried out on steel to be used for ship's side plating.

Q4. a) Enumerate the causes of vibration in diesel machinery and shafting. (5)

b) Describe procedures by which it may be reduced by operating personnel, suitable design and devices. (6)

c) State the possible effects of vibration on machinery and crewmembers. (5)

Q8.  With reference to fatigue of engineering components;

(a) Draw an S/N curve for steel, showing the fatigue limit and two representative stress cycle condition on the graph

(b) Explain how a component is designed to avoid fatigue failure, suiting the S/N curve drawn in part (a)

(c) Explain how poor maintenance and incorrect machinery operation can result in fatigue failure even though a component is designed to operate below the fatigue limit.