Name- Dinesh R Bajaj
Venue : SAC Ahmedabad
Interview reporting time : 8 AM
Interview happened at : 8 PM
DATE: 23 DEC 2016
After filling some forms we all aspirants were made to sit in a meeting hall. Slowly one by one people were called for interview. My turn came after 12 long hours . I was second last person to enter the cabin.
Upon entering I see 7-8 people sitting on a oval table all facing a board. I was asked to sit on a chair near the board. My certificate Folder was in my hand but they didn’t even ask for it.
M1- So Mr. Bajaj you come from Maharashtra, is Rahul bajaj your distant relative ?
Me- No sir ( all laughed )
M1- ok. Vey briefly can you tell us about your project in college?
Me- explained him.( He didnt not go in details)
M1- ok. What subjects do u like?
Me- Som, FM , HT, tom.
M1- ok.Draw a beam on board with both ends fixed. And show me what reactions will be there if u load it with UDL..!
Me- drew. Moments on both sides. Vertical and horizontal reaction on both. ( Ma,Mb, Va, Vb, Ha, Hb)
M1- now tell me is this beam determinate or indeterminate?
Me- indeterminate sir.
Me- sir we have three equilibrium equation..( i wrote them on board, Fx, Fy and M = 0) But unknowns are 6.. hence indeterminate problem.
M1 – good. Now how will u proceed.
Me – i will bring in more equations sir. Deflection at centre is maximum hence slope is zero, beam changes curvature… , and slope and each fixed end is zero.
M1- good . 3+2 now we have 5 equations. U need one more what do u do?
Me- Sir, we can imagine to remove fixed support on right side. N imagine the deflection δ due to UDL on this end. Now apply Vb on right side imagining that this Can reaction is countering the deflection δ n bringing it to zero. Hence we get a deflection equation in terms of δ and Vb. Total 6 equation now.
M1- Very good. Just write all equations on board so that we can see.
M1- ok fine M2-Do u know about dynamic loading and design?
Me- yes sir.
M2- explain how u design for dynamic loads
Me- Sir we use endurance limit for designing such components. (Stress amplitude, mean stress was explained).
M2- draw a graph and explain us
Me- drew soderberg line, Gerber’s parabola etc but I committed a blunder. (X and Y axis got interchanged mistakenly)
M2- do u think the graph is correct?
Me – yes sir
M2- No it’s not correct. Plz correct it.
Me-( I was silent for two minutes. Then he corrected me).. I was like ok ok sir my mistake.
M3- write down the 3 dimensional heat conditional equation.
Me- ( wrote it down)
M3- for a plane slab how will you apply this equation.
Me-(used only one dimensional terms)
M3- for different boundary conditions how will the equation vary?
Me- ( I wrote for insulated boundary, convective boundary, boundary with radiation, then heat generation, without heat generation etc. All such cases I explained)
M3- in internal heat generation , what is the temperature profile in slab?
Me- parabolic sir
M3- how did u get it?
Me- one dimensional heat conduction with internal heat generation equation if solved gives T² term proportional to thickness X. Hnece parabolic.
M3- that’s correct
M4- okay so what is difference between refrigeration and air conditioning..
Me- Sir refrigeration means maintaining Temp below ambient. Whereas air conditioning can be used to either have cooler or hotter temp. Refrigeration does not speak about quality of air, but air conditioning speaks about humidity velocity, draft of air.
M4- what is humidity?
Me- I explained as kg vap/ kg of air
M4- Air coolers , what is the principle, would they work in Ahmedabad?
Me- yes sir. Evaporation causes cooling. Can work in dry environment. Not in a coastal region.
M4- ok. What is dehumidification?
Me- removal of water vapour from air……
M5- ok. I see u have been into business previously . what was it.?
Me- Paints sir.
M5- can u tell me difference between paints and Coating?
Me- Paints are for decoration purposes. They might cause protection of surface also. Whereas coating have main purpose of protecting or surface enhancing, shining, non corrosion..etc… Paints are subset of Coating.
M6- what is cruising speed of an automobile?
Me- (I was totally not having stamina to explain) sir, it’s the speed with which automobile moves most of the time.. All started laughing..( actual ans was most economical speed 35-40kmph)
M1- ok Mr. Bajaj u can go now.
Me- thanks sir. In short my interview was purely tech and went on for 30 mins.. main key was being confident and my experience in teaching helped me to be confident on explaining on board. Key is to the point answers and don’t be scared. They help u if you go wrong. Hence just never panic inside interview hall.
I got 81 mks in interview and topper was of 83. My AIR in list was 7th out of 800 people interviewed for mech. Share this so it helps maximum aspirants. All the best!