3 1 ii mid dme questions & bits [pls vist our blog sres11jemeches]

1 3-1 II MID D.M.E QUESTIONS & BITS.

Questions :-

1. (a) A single riveted lap joint, jointing two mild steel plates of 10mm think each, is required to resist each a load of 200kN.determine the diameter, pitch, and number of rivets required for the joint. The allowable stresses for both plate and rivet material is 60MPa in tensile, 90MPa in compression and 45 MPa in shear.

(b).Explain caulking and fullering with respect to the riveted joint.

2. (a)what hole must be drilled in the head of the bolt M36,to make uniform strength?

(b)A bolt used to fasten two members together. The members and the bolt are of the same material and have the same cross section area .Determine what external load W2 will cause separation of the members to occur if the initial tightening load W1 is 20KN.

3. Sketch and explain the design procedure for a knuckle joint.

4. ( a ) Design double riveted chain type butt joint for plates having 10mm thickness. Find the efficiency of the joint .Assume the allowable stress is 95N/mm2 in tension, 80N/mm^2 in shear and 155 N/mm2 in compression.

( b ) what is the difference between structure and pressure vessel riveted joints?5. Sketch and explain the design procedure for a cotter joint with Gib.

6. (a) Explain the procedure for the design of a circumferential lap riveted joint for a boiler.

(b) Explain advantages and disadvantages of riveted joints.

7. (a) what do you understand by ‘bolts of uniform strength’? How these are obtained?

(b) Calculate the size of the bolt required for the four hole bracket as shown in figure -5.8.use coarse threads and the allowable stress of 30 N/mm^2.

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8. Two lengths of pipes, outside diameter 50mm, are connected by means of sleeve and two taper pins to form a joint. The joint carries 10 KN tensile load. Design the joint and give a near dimensioned sketch. Select suitable materials and the design stresses for all the parts.

9. An overhung shaft carries a 1m diameter pulley, whose centre is 250mm from the centre of the nearest bearing. The weight of the pulley is 600N and angle of lap of the belt may be assumed as 1800

. The pulley is driven be a motor, placed below it at an angle of 450 . If the permissible tension in the shaft. Assume the permissible shear stress in the shaft is 0.3; determine the size of the shaft. Assume the permissible shear stress in the shaft material as 50MPa.Take shock and fatigue factors for torsion and bending as 22 and 1.5 respectively. Check the design for lateral stiffness and torsional stiffness.

10.(a) Explain about various types of stresses acting on a rotating shaft.

(b) Explain the effect of key way on the strength of a shaft.

BITS :-RIVETS

1. A rivet is specified by(a) shank diameter (b) length of rivet (c) type of head (d) length of tail2. The diameter of the rivet hole is usually ............ the nominal diameter of the rivet. (a) equal to (b) less than (c) more than

3. The rivet head used for boiler plate riveting is usually (a) snap head (b) pan head (c) counter sunk head (d) conical head

4. According to Unwin’s formula, the relation between diameter of rivet hole (d) and thickness of plate(t) is given by (a) d = t (b) d = 1.6 t (c) d = 2 t (d) d = 6 t where d and t are in mm.5. A line joining the centres of rivets and parallel to the edge of the plate is known as (a) back pitch (b) marginal pitch (c) gauge line (d) pitch line

6. The centre to centre distance between two consecutive rivets in a row, is called (a) margin (b) pitch (c) back pitch (d) diagonal pitch



7. The objective of caulking in a riveted joint is to make the joint (a) free from corrosion (b) stronger in tension (c) free from stresses (d) leak-proof

8. A lap joint is always in .....shear. (a) single (b) double

9. A double strap butt joint (with equal straps) is (a) always in single shear (b) always in double shear (c) either in single shear or double shear (d) any one of these

10. Which of the following riveted butt joints with double straps should have the highest efficiency asper Indian Boiler Regulations? (a) Single riveted (b) Double riveted (c) Triple riveted (d) Quadruple riveted

11. If the tearing efficiency of a riveted joint is 50%, then ratio of diameter of rivet hole to the pitch of rivets is (a) 0.20 (b) 0.30 (c) 0.50 (d) 0.60

12. The strength of the unriveted or solid plate per pitch length is equal to (a) p × d × t (b) p × t × t (c) (p – t ) d × t (d) (p – d ) t × t

13. The longitudinal joint in boilers is used to get the required(a) length of boiler (b) diameter of boiler(c) length and diameter of boiler (d) efficiency of boiler

14. For longitudinal joint in boilers, the type of joint used is(a) lap joint with one ring overlapping the other (b) butt joint with single cover plate(c) butt joint with double cover plates (d) any one of these

15. According to Indian standards, the diameter of rivet hole for a 24 mm diameter of rivet, should be(a) 23 mm (b) 24 mm(c) 25 mm (d) 26 mm

Cotter and Knuckle Joints



1. A cotter joint is used to transmit (a) axial tensile load only (b) axial compressive load only (c) combined axial and twisting loads (d) axial tensile or compressive loads

2. The taper on cotter varies from (a) 1 in 15 to 1 in 10 (b) 1 in 24 to 1 in 20 ( c) 1 in 32 to 1 in 24 (d) 1 in 48 to 1 in

3. Which of the following cotter joint is used to connect strap end of a connecting rod ? (a) Socket and spigot cotter joint (b) Sleeve and cotter joint (c) Gib and cotter joint (d) none of these

4. In designing a sleeve and cotter joint, the outside diameter of the sleeve is taken as (a) 1.5 d (b) 2.5 d (c) 3 d (d) 4 d where d = Diameter of the rod.5. The length of cotter, in a sleeve and cotter joint, is taken as (a) 1.5 d (b) 2.5 d (c) 3 d (d) 4 d

6. In a gib and cotter joint, the thickness of gib is .......thickness of cotter. (a) more than (b) less than (c) equal to

7. When one gib is used in a gib and cotter joint, then the width of gib should be taken as (a) 0.45 B (b) 0.55 B (c) 0.65 B (d) 0.75 B where B = Total width of gib and cotter.

8. In a steam engine, the piston rod is usually connected to the crosshead by means of a (a) knuckle joint (b) universal joint (c ) flange coupling (d) cotter joint

9. In a steam engine, the valve rod is connected to an eccentric by means of a (a) knuckle joint (b) universal joint (c) flange coupling (d) cotter joint



10. In a turn buckle, if one of the rods has left hand threads, then the other rod will have (a) right hand threads (b) left hand threads (c) pointed threads (d) multiple threads

Bolts & nuts

1. The largest diameter of an external or internal screw thread is known as (a) minor diameter (b) major diameter (c) pitch diameter (d) none of these

2. The pitch diameter is the ...................... diameter of an external or internal screw thread. (a) effective (b) smallest (c) largest

3. A screw is specified by its (a) major diameter (b) minor diamet (c) pitch diameter (d) pitch

4. The railway carriage coupling have (a) square threads (b) acme threads (c) knuckle threads (d) buttress threads

5. The square threads are usually found on (a) spindles of bench vices (b) railway carriage couplings (c) feed mechanism of machine tools (d) screw cutting lathes

6. A locking device in which the bottom cylindrical portion is recessed to receive the tip of the lockingset screw, is called (a) castle nut (b) jam nut (c) ring nut (d) screw nut

7. Which one is not a positive locking device ? (a) Spring washer (b) Cotter pin (c) Tongued washer (d) Spring wire lock

8. The washer is generally specified by its (a) outer diameter (b) hole diameter (c) thickness (d) mean diameter



9. A locking device extensively used in automobile industry is a (a) jam nut (b) castle nut (c) screw nut (d) ring nut

10. A bolt of M 24 × 2 means that (a) the pitch of the thread is 24 mm and depth is 2 mm (b) the cross-sectional area of the threads is 24 mm2 (c) the nominal diameter of bolt is 24 mm and the pitch is 2 mm (d) the effective diameter of the bolt is 24 mm and there are two threads per cm

11. When a nut is tightened by placing a washer below it, the bolt will be subjected to (a) tensile stress (b) compressive stress (c) shear stress (d) none of these

12. The eye bolts are used for (a) transmission of power (b) locking devices (c) lifting and transporting heavy machines (d) absorbing shocks and vibrations

13. The shock absorbing capacity of a bolt may be increased by (a) increasing its shank diameter (b) decreasing its shank diameter (c) tightening the bolt properly (d) making the shank diameter equal to the core diameter of the thread.

14. The resilience of a bolt may be increased by (a) increasing its shank diameter (b) increasing its length (c) decreasing its shank diameter (d) decreasing its length

15. A bolt of uniform strength can be developed by (a) keeping the core diameter of threads equal to the diameter of unthreaded portion of the bolt (b) keeping the core diameter of threads smaller than the diameter of unthreaded portion of the bolt (c) keeping the nominal diameter of threads equal to the diameter of unthreaded portion of bolt (d) none of the above



Shafts

1. The standard length of the shaft is (a) 5 m (b) 6 m (c) 7 m (d) all of these

2. Two shafts A and B are made of the same material. The diameter of the shaft A is twice as that of shaftB. The power transmitted by the shaft A will be ........... of shaft B. (a) twice (b) four times (c) eight times (d) sixteen times

4. Two shafts will have equal strength, if (a) diameter of both the shafts is same (b) angle of twist of both the shafts is same (c) material of both the shafts is same (d) twisting moment of both the shafts is same

5. A transmission shaft subjected to bending loads must be designed on the basis of (a) maximum normal stress theory (b) maximum shear stress theory (c) maximum normal stress and maximum shear stress theories (d) fatigue strength

6. Which of the following loading is considered for the design of axles ? (a) Bending moment only (b) Twisting moment only (c) Combined bending moment and torsion (d) Combined action of bending moment, twisting moment and axial thrust

7. When a shaft is subjected to a bending moment M and a twisting moment T, then the equivalent twisting moment is equal to (a) M + T (b) M 2 + T 2 (c) M2 T 2 (d) M2 – T 2

8. The maximum shear stress theory is used for (a) brittle materials (b) ductile materials (c) plastic materials (d) non-ferrous materials

9. The maximum normal stress theory is used for (a) brittle materials (b) ductile materials



(c) plastic materials (d) non-ferrous materials

10. The design of shafts made of brittle materials is based on (a) Guest’s theory (b) Rankine’s theorya (c) St. Venant’s theory (d) Von Mises Theory


3 1 ii mid dme questions & bits [pls vist our blog sres11jemeches]

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