ME 04 606-DYNAMICS OF MACHINERY JUNE 2007 (2004 Admissions)

SUBJECT - DYNAMICS OF MACHINERY

CODE -  04 606

SEMESTER - SIXTH

BRANCH - ME

UNIVERSITY - CALICUT

YEAR - 2007

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Part A

Answer all Questions

I.(a) Write down the condition of static equilibrium of two force members, three force members and member with two forces and a torque.

  (b) Explain with an example "method of virtual work".

  (c) Explain the effects of partial balancing in locomotives.

  (d) Define the terms 'primary' and 'secondary' balancing as used for balancing of reciprocating engines.

  (e) What is meant by "logarithmic decrement" ? Find an expression for logarithms decrement in term of clamping factor.

  (f) Explain the term "vibration isolution" and transmissiblity".

  (g) What is meant by "co-ordinate coupling" ?

  (h) What is meant by "Normal mode of vibration".

(8x5=40 marks)

II. (a) Determine the required input torque on the crank of a slider crank mechanism for the static equilibrium.When the piston load in 1500 N.The length of the crank and connecting rod are 40 mm and 100 mm respectively and crank has turned through 45 degree from the inner dead centre.

Or

    (b) Determine the inertia force magnitude and location of each link for a four bar mechanism with following data :

O2A = 25 cm Mass= 2.5 kg(crank)

AB = 30 cm Mass = 1 kg

O4B = 30 cm Mass = 2.5 kg

O2O4 = 50 cm (Fixed link)

<AO2O4 = 60degree,The crank O2A rotates with a speed for 2500 r.p.m counts clockwise.The centre of gravity of each link is at its midpoint.

(15 marks)

III. (a)The cranks of a four cylinder marine oil engine are arranged at angular interval of 90 degree.The engine's speed is 70 r.p.m and reciprocating mass per cylinder is 800 kg. The inner cranks are 1 m apart and are symmetrically arranged between the outer cranks which are 2.6 m apart.Each crank is 400 mm long.Determinet he filing order of the cylinders for the best balance of reciprocating masses and also the magnitude of the unbalanced primary couple for the arrangement.

Or

     (b) A 90degree V engine has two cylinders which are placed symmetrically.The two connecting rods operate a common crank.The length of the connecting rods are 320 mm each and crank radius in 80 mm.The reciprocating mass per cylinder is 12 kg.If the engine speed is 600 r.p.m.,then find the resultant primary and secondary forces.Also find the maximum resultant secondary force

(15 marks)

IV.  (a) A mass 'M' is attached to one end of a spring of stiffness 'k' having natural frequency of 6 Hz.When 1 kg mass is attached with 'm' the natrual frequency of the system is lowered by 20%.Determine the value of mass 'm' and stiffness 'k'.

Or

     (b A vibrating body is supported by six isolates each having stiffness 32 kN/m and 6 dash pots having damping factors as 400 N sec/m.The vibrating body is to be isolated by a rotating device having an amplitude 0.06 mm at 600 r.p.m. Take m=30kg.Dtermine (i) the amplitude of vibration of the body (ii) dynamic load on each isolate due to vibration.

(15 marks)

V. (a) Determine the principal co-ordinates of the system shown in figure if m1=m2=m and k1=k2=k3=k

Or

   (b)The moments of inertia of three rotors A,B and C are 0.3,0.6 and D 18 kgm^2 respectively.The distance between A and B is 1.5 m and between B and C is 1m.The shaft is 70 mm in diameter and G=8.4 x 10^9 N/m^2.Find (i) frequencies of torsional vibrations. (ii) position of nodes (iii) amplitude of vibration.

(15 marks)

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