JNTU
JNTU B.Tech II DESIGN OF MACHINE MEMBERS I Previous Question Paper (September/October - 2023 - R16)
i) Question paper consists of Part A, Part B.
ii) Part A is compulsory, which carries 25 marks. In Part A, answer all questions.
iii) In Part B, Answer any one question from each unit. Each question carries 10 marks and may have a, b as sub questions.
PART - A
25 Marks
What is Stress concentration?
Answer
Stress concentration is the localized increase in stress intensity at regions of geometric discontinuities, such as holes, notches, fillets, or keyways, where the stress distribution is no longer uniform and exceeds the nominal stress calculated by standard formulas.
Draw S-N Curve and mark all silent points.
Answer
The S-N curve represents the relationship between the alternating stress amplitude (S) and the number of cycles to failure (N). Key points include the Ultimate Tensile Strength (S_u) at N=10^3 cycles, the Endurance Limit (S_e) for ferrous materials at 10^6 cycles, and the transition region between finite life and infinite life.
What is the expression for the efficiency of a riveted joint?
Answer
Sign in to view the complete answer paper.
How do you obtain a bolt of uniform strength?
Answer
Sign in to view the complete answer paper.
What are the advantages of spigot and socket joint?
Answer
Sign in to view the complete answer paper.
Sketch and write the application of the following keys: i) Flat saddle key, ii) Hollow saddle key
Answer
Sign in to view the complete answer paper.
What is equivalent bending moment?
Answer
Sign in to view the complete answer paper.
What is coupling? Mention the advantages of shaft couplings?
Answer
Sign in to view the complete answer paper.
Differentiate Solid length and free length of a spring.
Answer
Sign in to view the complete answer paper.
What is stiffness? How it influence the performance?
Answer
Sign in to view the complete answer paper.
PART - B
50 Marks
A hollow shaft of 40 mm outer diameter and 30 mm inner diameter is subjected to a twisting moment of 100 N-m, simultaneously, it is subjected to an axial thrust of 15 kN and a bending moment of 75 N-m. Calculate the maximum compressive and shear stresses.
Answer
Sign in to view the complete answer paper.
A machine component is subjected to fluctuating stress that varies from 40 to 100 N/mm2. The corrected endurance limit stress for the machine component is 270 N/mm2. The ultimate tensile strength and yield strength of the material are 600 and 450 N/mm2 respectively. Find the factor of safety using Soderberg line.
Answer
Sign in to view the complete answer paper.
A cantilever beam made of cold drawn steel 4OC8 (Sut = 600 N/mm2 and Syt = 380 N/mm2) is shown in Figure 1. The force P acting at the free end varies from –50 N to +150 N. The expected reliability is 90% and the factor of safety is 2. The notch sensitivity factor at the fillet is 0.9. Determine the diameter ‘d’ of the beam at the fillet cross-section.
Answer
Sign in to view the complete answer paper.
A plate, 75 mm wide and 10 mm thick, is joined with another steel plate by means of single transverse and double parallel fillet welds, as shown in Figure 2. The joint is subjected to a maximum tensile force of 55 kN. The permissible tensile and shear stresses in the weld material are 70 N/mm2 and 50 N/mm2 respectively. Determine the required length of each parallel fillet weld.
Answer
Sign in to view the complete answer paper.
A wall bracket is attached to the wall by means of four identical bolts, two at A and two at B, as shown in Figure 3. Assuming that the bracket is held against the wall and prevented from tipping about the point C by all four bolts and using an allowable tensile stress in the bolts as 30 N/mm2, determine the size of the bolts on the basis of maximum principal stress theory.
Answer
Sign in to view the complete answer paper.
Design a cotter joint to connect two mild steel rods for a pull of 30 kN. The maximum permissible stresses are 55N/mm2 in tension, 40N/mm2 in shear and 70 N/mm2 in crushing. Draw a neat sketch of the joint.
Answer
Sign in to view the complete answer paper.
Design a knuckle joint for a axial load of 60 kN. The yield strength of the material is 400N/mm2. The factor of safety is 6.(Assume suitable data if necessary)
Answer
Sign in to view the complete answer paper.
A shaft is required to transmit 60 kW power at 800 rpm. It is a hollow shaft, having an inside diameter 0.8 times of the outside diameter. It is made of steel (Syt = 380 N/mm2) and the factor of safety is 4. Calculate the inside and outside diameters of the shaft. Assume (Ssy = 0.5Syt).
Answer
Sign in to view the complete answer paper.
Design and make a neat dimensioned sketch of a muff coupling which is used to connect two steel shafts transmitting 40 kW at 350 r.p.m. The material for the shafts and key is plain carbon steel for which allowable shear and crushing stresses may be taken as 40 MPa and 80 MPa respectively. The material for the muff is cast iron for which the allowable shear stress may be assumed as 15 MPa.
Answer
Sign in to view the complete answer paper.
A helical spring is made from a wire of 6 mm diameter and has outside diameter of 60 mm. If the permissible shear stress is 300 MPa and modulus of rigidity 80 kN/mm2, find the axial load which the spring can carry and the deflection per active turn.
Answer
Sign in to view the complete answer paper.
Design a helical compression spring for a maximum load of 1000 N for a deflection of 25 mm using the value of spring index as 5. The maximum permissible shear stress for spring wire is 420 MPa and modulus of rigidity is 84 kN/mm2. Take Wahl’s factor, K = (4C-1)/(4C-4) + 0.615/C, where C = Spring index.
Answer
Sign in to view the complete answer paper.