Summer 2015 Strength of Materials Question Paper

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GUJARAT TECHNOLOGICAL UNIVERSITY
DIPLOMA ENGINEERING – SEMESTER – III • EXAMINATION – SUMMER 2015
Subject Code: 3331904 Date: 14-05- 2015
Subject Name: Strength Of Material
Time:2:30 pm to 5:00 pm Total Marks: 70

Instructions:
1. Attempt all questions.
2. Make Suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.
4. Use of programmable & Communication aids are strictly prohibited.
5. Use of only simple calculator is permitted in Mathematics.
6. English version is authentic.

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Q.1 Answer any seven out of ten. 14

1. Define young’s modulus and Poisson’s ratio.

2. State law of principle of superposition.

3. State parallel axis theorem.

4. Define continuous beam and fix beam.

5. Define factor of safety and bulk modulus.

6. Draw shear force distribution diagram for I-section and Angle section.

7. Define slenderness ratio and critical load.

8. What is limit of eccentricity?

9. What is principle plane and principle stress?

10. Differentiate between Ductility and Brittleness.

Q.2 (a) A mild steel bar, 2400mm2 in cross-section is subjected to axial forces as shown in fig.1.If Young’s modulus is 200GPa then find deformation developed in length of the bar. 03

OR

(a) If Young’s modulus (E) and Poisson’s ratio (v) are 200 GPa and 0.25 respectively then find shear modulus (G) and bulk modulus(K). 03

(b) The deformation in the diameter is 0.004 mm, when 32mmϕ bar subjected to 80 kN axial load. If shear modulus is 80 GPa, find Young’s modulus, Bulk modulus and Poisson’s ratio. 03

OR

(b) Mild steel bar, 3m long and 16 mm ϕ, is fixed between two walls at 300K temp. Find the reaction exerted on the wall in the following cases, when it is heated to 390K. (i) Walls are non-yielding and (ii) walls yield by 2mm. For steel, E = 210 GPa and α =12×10-6/K. 03

(c) For an unequal angle 100 × 90 ×10 mm, find MI about XX and YY axis passing from the centroid. 04

OR

(c) Construct SFD and BMD for a simply supported beam as shown in Fig.2. 04

(d) I-section (Symm) is used for 2 m cantilever bracket. Its both flanges and web are 10mm thick. Flanges are 100mm wide and overall depth of beam is 300 mm. If maximum bending stress is 150 MPa then keeping FOS 4, what is the point load applied at free end? Neglect self weight. 04

OR

(d) A beam, rectangular in section , has depth 500 mm and MI = 3.125×109 mm4 . If it is simply supported and carrying full UDL of 200 kN/m then maximum bending stress is 128 MPa. Find its span. 04

Q.3 (a) By applying point load at centre of 3 m simply supported beam , the maximum slope obtained is 10. Find the maximum deflection. 03

OR

(a) 4 m cantilever beam has 250 × 400 mm rectangular section. It carries full span UDL of 98 kN/m. If self weight of beam is 2 kN/m and E = 160GPa , then find the maximum slope and deflection. 03

(b) A hollow circular column, having 300mm ϕ external and 200mm ϕ internal, has a length of 5m. Its one end is fixed and other end is hinged. Find Euler load keeping FOS 3. Take E = 200 GPa. 03

OR

(b) Explain Effective length (Le) and End fixity constant. 03

(c) If the maximum stress induced is 12 MPa due to load applied at midpoint of an edge of 300 mm square,then find maximum stress and load applied. 04

OR

(c) Define : (i) Modulus of rupture (ii) Beam of uniform strength (iii) Moment of resistant. 04

(d) Describe points to be kept in mind while drawing SF and BM diagrams. 04

OR

(d) Draw core for a hollow circular section having 480mm ϕ external and 360 mm ϕ internal. 04

Q.4 (a) The maximum shear stress induced, in a 50mm ϕ solid circular shaft rotating at 150RPM, is 80 MPa. Find power required. 03

OR

(a) 8 m long hollow circular shaft of external 400mm ϕ and internal 200mm ϕ is subjected to a torque of 200kJ. If C = 82 GPa then find the maximum shear stress and angle of twist. 03

(b) Write down equation for torsion and explain each term. 04

OR

(b) Write the Euler’s formula for crippling load and state assumptions. 04

(c) For a stress system as shown in fig.3, find: (a) Principal Stress (b) Principal Planes (c) Max/Min shear stress (d) Their planes and (e) Normal stress on planes of Max/Min shear stress. (Use Graphical Method). 07

Q.5 (a) Differentiate between Charpy Impact test and Izod Impact test. 04

(b) If an impact load of 150N released from 80 mm height and applied at the end of a mild steel bar, 2 m long and 16mm ϕ then find instantaneous stress induced and increase in the length of a bar.
For steel E = 200 GPa. 04

(c) Define : Proof resilience and Modulus of resilience . 03

(d) 24 kN/m UDL is acting on a full span of simply supported beam. For beam, I = 80×106 mm4 and E = 200 GPa. If maximum deflection due to load is 5mm then find the beam span. 03


FIG 1.

FIG 2.

FIG 3

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