8/18/2019 Midsem Question Paper 2015

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BIRLA INSTITUTE OF TECHNOLOGY AND SCIENCE, PILANIME/MF F 244: Kinematics and Dynamics of Machines

SECOND SEMESTER 2014-2015Mid Semester Examination (CLOSED BOOK) 

Max Marks: 35 Duration: 90 mins Date: 9th

 March, 2015 (9 - 10:30 AM)

Q1a. What is the assumption in analysis of mechanisms which allows treatment of kinematics and

dynamics separately? Explain [1] 

Q1b. Which follower motion do you recommend for a high-speed cam and why? [1]

Q1c. Refer Fig Q1c, Determine the number of degrees of freedom associated with this machine.Links 3 and 4, 5 and 6, 8 and 9 form piston-cylinder pair. [3]

Fig Q1c Fig Q2

 All calculations and diagrams for question 2 and 3 are to be done in the drawing sheet provided .

Q2.  In the mechanism shown in Fig Q2, the angular velocity of link 2 is 2 rad/s (CCW) and theangular acceleration is 5 rad/s

2 (CW). Various lengths of the links are  AC  = 5.2 length unit,

 AB = 6 units, and CD = 10 units.

(a)  Draw position diagram and mention scale. [2] (b)  Draw velocity and acceleration diagrams and mention their scales. [3+4] 

(c)  Draw a table and tabulate the magnitudes of  the velocities and accelerations of slider B and point D. [2+4]   the angular velocity and angular acceleration of link CD (i.e. ω4 and α4).  [1+2] 

Q3.  Layout profile of a cam operating a flat-faced, translating, radial follower and with the

following data:Base circle radius = 40 mm

Total rise = 40 mm

The rise occurs with SHM over 90o  of cam rotation. The follower dwells for 100

o  of cam

rotation prior to the beginning of the rise and dwells 80o of cam rotation at the end of the rise.

Then the follower lowers down during the rest of the cam rotation with uniform motion.

If the cam rotates at uniform speed of 150 rpm in counter clock-wise direction, calculate the

maximum velocity and acceleration of the follower during the rise.  [12]