4020310-STRENGTH OF MATERIALS IMPORTANT QUESTIONS

 

4020310-STRENGTH OF MATERIALS IMPORTANT QUESTIONS – QUESTION BANK

 

UNIT-1 ENGINEERING MATERIALS

  PART-A

1.          Differentiate elasticity and plasticity.

2.                    Differentiate stiffness and toughness.

3.                    Differentiate between ductility and malleability.

4.                    Describe the types of cast iron.

5.                    What is steel? Give its major classification.

6.                    What is mean by force of friction and limiting force of friction.

7.                    Differentiate between static and dynamic friction.

8.                    What is mean by angle of friction?

9.          What is mean by cone of friction?

10.          Define coefficient of friction.

PART-B

1.        List out the various mechanical properties of material. Explain any eight properties.

2.      List out the types of cast iron. Explain the effects of impurities in cast iron.

3.      Explain the stress-strain diagram for mild steel specimen with its salient points. (Tension test on ductile material in UTM)

4.      List out the hardness testing method. Explain any two in detail.

5.      Explain the various impact testing methods with neat sketch.

6.      Explain the method of conducting fatigue test with neat sketch.

7.      Explain the method of conducting creep test with neat sketch.

8.      A specimen of steel 25 mm in diameter with a gauge length of 200 mm was tested in a laboratory. The following data were referred.

Maximum load = 140 KN, load at yield point = 110 KN, load at fracture = 120 KN, the diameter at neck 12.5 mm and distance between gauge points after fracture = 252 mm. Find the (i) yield stress (ii) Ultimate stress (iii) Nominal stress at fracture (iv) Percentage elongation (v) percentage of reduction in area.

UNIT-2 DEFORMATION OF METALS 

PART-A

1.        States Hook’s Law.

2.      Differentiate between Factor of safety and Load factor.

3.      Define Poisson’s Ratio.

4.      Define proof resilience and Modulus of resilience..

5.      Write down the expression for the stress induced due to impact load and suddenly applied load.

6.      A mild steel rod of 25mm diameter and 200mm long is subjected to an axial pull of 75KN. If the E = 2x105 N/mm2, determine elongation of the bar.

7.      A cement concrete cube of 150mm size crushes at a load of 300KN. Determine the working stress. Take factor of safety is 3.

8.      Find the strain energy that can be stored in a steel bar of 45mm in diameter and 3m long subjected to a Pull of 105 KN. Take E = 200KN/mm2. The rod subjected to a gradually applied load.

9.      Find the maximum stress and extension in bar 2m long and 25mm diameter when it is subjected to a suddenly applied load of 50 KN. Take E = 200KN/mm2.

PART-B

 

1.        A circular bar of 20 mm diameter and 300 mm long is carries a tensile load of 30KN. Find the stress, strain and elongation of the bar. Take E=2x105 N/mm2

2.      A steel bar of 20 mm wide, 10mm thick and 2m long is subjected to a Pull of 20 KN along its length. Find the changes in dimensions and volume of the bar. Take Young’s Modulus E= 2x105 N/mm2 and Poisson’s Ratio 1/m = 0.3.

 

 

3.      A steel rod of 2m long 20 mm diameter is subjected to axial load of 45KN. Find the change in diameter and change in volume of the rod. Take E =2x105 N/mm2 and m=3.

4.      A circular bar of length 150mm diameter 50mm is subjected to an axial load of 400KN. The extension in length and contraction in diameters are found to be 0.25mm and 0.02 mm respectively after loading. Calculate the (i) Poisson’s ratio (ii) Young’s Modulus (iii) Bulk Modulus and (iv) Rigidity Modulus.

 

5.      A material has Young’s Modulus of 120 GPa and Rigidity Modulus of 50 GPa. Find the value of Poisson’s Ratio and Bulk Modulus.

 

UNIT-3 GEOMETRIC PROERTIES OF SECTIONS AND THIN SHELLS 

PART-A

1.        Differentiate centre of gravity and centroid.

2.      Define axis reference and axis of symmetry.

3.      Define moment of inertia.

4.      State parallel axis theorem.

5.      State perpendicular axis theorem.

6.      Define polar moment of inertia.

7.      What is mean by radius of gyration.

8.      What is mean by section modulus.

9.      Distinguish between thin shell and thick shell.

10.   State the nature of stresses induced in thin cylindrical shell.

11.     Write down the expression for hoop stress and longitudinal stress induced in the cylindrical shell.

12.   A boiler 3m internal diameter is subjected to an internal pressure of 6 bar. Find the hoop stress and longitudinal stress if the thickness of boiler plate is 12mm.

13.   A boiler 2.8m internal diameter is subjected to a steam pressure of 0.8 N/mm2. Find the hoop stress and longitudinal stress, if the thickness of boiler plate is 10 mm.

 

 

14.   Calculate the working pressure may be allowed in a boiler shell 1.8 m diameter with plates 15mm thick. If the permissible stress in solid plate is not to exceed 70 N/mm2.

 

15.   A thin cylindrical shell of 1m diameter is subjected to an internal pressure of 1 N/mm2. Find the suitable thickness of shell, if the ultimate tensile strength of the plate is 400 N/mm2. Take factor of safety as 4.

 

16.   A spherical vessel 3 m diameter is subjected to an internal pressure of 1.5 N/mm2 . find the thickness of the vessel required, if the maximum stress is not to exceed 90 N/mm2. Take the efficiency of the joint as 75%.

 

PART-B

1.        An angle section of 100 mm wide and 120 mm deep has both the flanges are 10 mm thick. Determine the centroid of the section.

2.      Find the centroid of an I section having top and bottom flange 200 x 40mm and web is 160 x40mm.

3.       The channel section of size 100 mm x 50 mm overall. The base as well as flanges of channel are 15mm thick. Determine the centroid of the channel.

4.       Find the centroid of an inverted T section with flange 150x 20mm and web is 100x25mm.

5.      5. Find the values of Ixx and Iyy of a T section 120mm wide and 120 mm deep overall. Both the web and flange are 10 mm thick. Also find out its radius of gyration about its axes.

6.       A channel section of size 300mm and 100mm overall. The base as well as flange of the channel are 10 mm thick. Calculate the moment of inertia about its centroidal axes.

7.      Find the moment of inertia about the centroidal axes XX and YY of an angle section of size 90mm x75mm x20mm. Also calculate its radius gyration.

8.      An I section has the top flange 100mmx 15mm, web is 150mm x20mm and the bottom flange 180mmx 30 mm. calculate the moment of inertia Ixx and Iyy.

9.      A long steel tube 70 mm internal diameter and wall thickness 2.5 mm has closed ends and is subjected to an internal pressure of 10 N/mm2. Calculate the magnitude of hoop and longitudinal stress set up in the tube. If the efficiency of the longitudinal joint is 80% which stress is affected and what is its revised value?

10.    A cylindrical shell 3 m long 500mm in diameter is made up of 20 mm thick plate. If the cylinder is subjected to an internal pressure of 5 N/mm2, find the resulting hoop and longitudinal stress, change in diameter, change in length and change in volume. Take Poisson’s Ratio as 0.3 and E = 2x105 N/mm2.

 

11.     Calculate the increase in volume of a boiler 3m long and 1.5 m diameter, when subjected to an internal tensile stress is not to exceed 30N/mm2. Take Poisson’s Ratio as 0.28 and E = 2.1x105 N/mm2.

12.   A spherical shell of 1m internal diameter and 5 mm thick is filled with fluid until its volume increases by 0.2x106 mm3. Calculate the pressure exerted by the fluid on the shell. Take Poisson’s Ratio as 0.3 and E = 2x105 N/mm2.

 

13.   Calculate the depth to which a spherical float 200 mm diameter and 6 mm thickness has to be immersed in water in order that its diameter is decreased by 0.05 mm. Assume Poisson’s Ratio as 0.25 and E = 2x105 N/mm2 and specific weight of water is 9810 N/m3.

 

 

UNIT- 4 THEORY OF TORSION AMD SPRINGS PART-A

1.   What is mean by pure torsion?

2.  Write down the assumption made in theory of pure torsion.

3.  Write down the Torsion Equation.

4.  Define Polar modulus. State the formula for solid and hollow shafts.

5.  Define torsional strength and torsional rigidity.

6.  List out the advantages of hollow shaft over solid shaft.

7.  What are the types of spring? Give its uses.

8.  What are the laminated or leaf spring? Give its applications.

9. Compare open coil and closely coiled helical spring.

10. State the application of springs.

11.  Define stiffness or spring constant. Also write its formula.

12. State the expression for deflection in closely coil helical spring.

13. Calculate the power transmitted by a solid shaft 100 mm diameter running at 250 rpm, if the shear stress in the shaft material is not exceed 75 N/mm2.

 

14. A hollow shaft of external and internal diameters as 100 mm and 40 mm is transmitting power at 120 rpm. Find the power the shaft can be transmit, if the shear stress is not to exceed 50 N/mm2.

15. A closely coiled helical spring of alloy steel wire of 10 mm diameter having 15 complete turns with the mean coil diameter as 100 mm. calculate the stiffness of the spring. Take C = 90x103 N/mm2.

16.  A closely coiled helical spring made of 12mm steel wire having 12 turns of mean radius 60 mm elongates by 15mm under a load. Find the magnitude of load if modulus of rigidity is given as 7.5x104 N/mm2.

PART-B

 

1.        A closely coil helical spring made of steel wire of 10 mm diameter has 10 coils of 120 mm mean diameter. Calculate the deflection of the spring under an axial load of 100 N and the stiffness of spring.

2.      The mean diameter of closely coiled helical spring is 5 times the diameter of wire. It elongates 8 mm under an axial pull of 120N. if the permissible shear stress is 40 N/mm2, find the size of wire and number of coils in the spring. Take C = 0.8x105 N/mm2.

3.      Design a closely coiled helical spring of stiffness 20 N/mm. the maximum shear stress in the spring material is not to exceed 80 N/mm2 under a load of 600 N. the diameter of coil is to be 10 times the diameter of wire.Take C = 85x103 N/mm2.

4.      A weight of 150 N is dropped on to a compression spring with 10 coils of 12 mm diameter closely coiled to mean diameter of 150 mm. if the instantaneous contraction is 140 mm, calculate the height of drop. Take C = 0.8x105 N/mm2.

5.      A truck weighing 20 KN and moving at 6 Km/Hr has to be brought to rest by a buffer. Find how many springs each of 15 coils will be required to store the energy of motion during compression of 200 mm. the spring id made out of 25 mm diameter steel rod coiled to a mean diameter of 200 mm. Take C = 0.945x105 N/mm2.

 

UNIT -5 SF AND BM DIAGRAMS OF BEAMS AND THEORY OF BENDING PART – A

1.        Define beam. List out the types of beam with neat sketches.

2.      List out the various types of load acting on the beam.

3.      What is UDL and UVL?

4.      Define shear force and bending moment.

5.      Draw the sign convention of shear force and bending moment.

6.      Differentiate sagging and hogging moment.

7.      Write the relation between load, shear force and bending moment.

8.      What is mean by point of contraflexure?

9.      Draw the SFD and BMD for simply supported beam with UDL.

10.      Define simple bending or pure bending.

11.        Write down the assumption made in theory of simple bending.

12.      Define neutral axis.

13.      Write down bending equation or flexural formula.

14.      Define section modulus of beam.

15.      What is mean by moment of resistance?

16.      A cantilever 4m long carries a udl of 30KN/m over half of its length adjoining the free end. Draw SFD and BMD.

17.      A cantilever 2m long carries a point load of 3 KN at its free end and another point load of 2KN at a distance of 0.5 m from free end. Draw the shear force and bending moment diagrams.

18.      A steel wire of 5 mm diameter bent into circular shape of 5 m radius. Determine the maximum shear stress induced in the wire. Take E= 2x 105 N/mm2.

19.      A simply supported beam is 300 mm wide and 400 mm deep. Determine the stress at 40 mm above N.A, if the maximum bending stress is 15 N/mm2.

 

PART-B

1.        A cantilever 4m span carries a UDL of 10 KN/m for a length of 2.5m from the fixed end and two point loads of 20KN and 30KN at the free end and at 1.5m from the free end respectively. Draw SFD and BMD.

2.      A cantilever of 2m long carries a point load of 20 KN at 0.8 m from the fixed end and another point load of 5 KN at the free end. In addition, UDL of 15KN/m is spread over the entire length of cantilever. Draw the SFD and BMD.

3.      A simply supported beam of effective span 6m carries three point loads of 30KN,25KN and 40KN at 1m,3m and 4.5m respectively from the left support. Draw SF and BM diagrams.

4.      A simply supported beam of length 6m carries a UDL of 20KN/m throughout its length and a point load of 30Kn at 2m from the right support. Draw the shear force and bending moment diagrams.

5.      A simply supported beam of span 10 m carries a udl of 20 KN/m over the left half of the span and point load of30KN at the mid span. Draw the SFD and BMD.

6.      A simply supported beam AB of 8m length carries a udl of 5KN/m for a distance of 4m from the left support A. The rest of the beam of 4m carries an udl of 10KN/m. draw SFD and BMD.