Pondicherry University 2007-3rd Sem B.Tech ..Bio - medical engg. syllabus -2008 - Question Paper

B.tech DEGREE exam ,NOV 2007

3rd SEMESTER

BIO-MEDICAL ENGINEERING/CHEMICAL ENGINEERING

STRENGTH OF MATERIALS

Time :Three hours Maximum marks:75 marks


ans all ques..

UNIT –1

1.(a) Derive the relationship ranging from young’s modulus and rigidity modulus. (8)

(b) A bar 30mm * 30 mm * 250 mm long is subjected to a pull of 90kn in the direction of its length .The extension of the bar was obtained to be 0.125mm and the reduce in every lateral dimension is obtained to be 0.00375mm determine the Youngs modulus , Poison’s ratio, Modulus of rigidty and Bulk modulus for the material of the bar. (7)

(or)

2.(a) A rectangular block of material is subjected to a tensile stress of 100Mpa on a plane and a tensile stress of 55MP a on a plane at right angles ,together with hear stresses of 60Mpa on the identical planes.
Determine (8)

(i) the direction of the principal planes.
(ii) The magnitude of the principal stresses.
(iii) The magnitude of the greatest shear stress.

(b) How do you determine the principal stresses using Mohr’s circle? (7)

UNIT – 2

3. (a) A simply supported beam AB 10m long has supports at its ends A and B .It carries a point load load of 5Kn at 3m from A and a point load of 5Kn at 7m from A and a point load of 5Kn at 7m from A.draw shear force diagram and bending moment diagram. (8)


(b) A cylindrical shell 3.25m long ,1m in diameter is subjected to an internal pressure of one n/mm^2 . The thickness of the shell is 10mm and Youngs modulus E=2*10^5 n/mm^2.determine.

(i) the longitudinal stress
(ii) the hoop stress
(iii) the maximum shear stress
(iv) the modifications in the dimension of the shell. (7)


(or)

4.(a) A cantilever of span 2m carries concentrated loads of 400N,300N,800N and 500N at 0.5m ,1m,1.5m and 2m from the fixed end .Draw shear force and bending moment diagrams. (8)

(b) A timber beam 100mm wide and 150 mm deep supports a uniformly distributed load over a span of 2m .If the safe stresses are 28 N/mm^2 longitudinally and two N/mm^2 in transverse shears,determine the maximum load which can be supported by the beam. (7)

UNIT – 3


5.(a) A cantilever of length 2m carries a uniformly distributed load of 2500 N/m for a length of 1.25m from the fixed end .If the part is rectangular 120mm wide and 240mm deep,determine the deflection at the free end .the Young’s Modulus E=1 *10^5 N/mm^2. (8)

Earning:   Approval pending.