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# Note for Strength of Materials-2 - SM-2 by GNANAMOORTHY P

• Strength of Materials-2 - SM-2
• Note
• teegala krishne reddy engineering college - TKREC
• 5 Topics
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#### Note for Strength of Materials-2 - SM-2 by GNANAMOORTHY P

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TORSION AND SHAFT 1. Define Torsion? A shaft is said to be in torsion, when equal and opposite torques are applied at the two ends of the shaft. The torque is equal to the product of the force applied (tangentially to the ends of a shaft) and radius of the shaft. 2. What is Torque? Torque is produced due to a single force. It is the turning effect of a force. 2 Marks Q & A

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3. What is couple? Couple is produced due to two forces that are equal magnitude but in opposite direction (Unlike parallel forces) but do not have the same line of action. 5. What are the assumptions made in the theory of torsion? • • • • The material of the shaft is uniform throughout. The twist along the shaft is uniform. The shaft is of uniform circular section throughout. Cross sections of the shaft, which are plane before twist, remain plane after twist. • All radii which are straight before twist remain straight after twist 6. Write torsion equation 𝐓 𝛕 𝐂𝛉 = = 𝐉 𝐑 𝐋 T – Torque (or) Twisting moment (N.mm) J – Polar moment of Inertia (mm4) τ - Shear stress (N/mm2) R – Radius of the circular shaft (mm) C – Modulus of rigidity (N/mm2) Θ - Angle of twist L – Length of shaft 2 Marks Q & A

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7. Write the expression for power transmitted by a shaft P= 2πNT 60 Where, P – Power (KW) N – No. of rotation (rpm) T – Mean torque transmitted (kN.m) 𝜔 - Angular speed of shaft 8. Define Polar modulus (i) Solid shaft (ii) Hollow shaft Polar modulus is defined as the ratio of the polar moment of inertia to the radius of the shaft. It is also called torsional sectional modulus. It is denoted by ZP ZP = J R Where, J = Polar moment of inertia ZP = Polar modulus R = Radius For a solid shaft: ZP = π 3 D 16 2 Marks Q & A

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For a Hollow shaft: ZP = π X Do4 − Di4 16D0 9. The relation of maximum shear stress induced in a shaft subjected to twisting moment is given by τ R = Cθ L Where, 𝜏 − Maximum shear stress 𝑅 - Radium of shaft C – Modulus of rigidity 𝜃 – Angle of twist L – Length of the twist 10. When a circular shaft is subjected to torsion, the shear stress at any point varies linearly from the axis to the surface τ R = q r Where, 𝜏 − Maximum shear stress on the surface of the shaft 𝑅 - Radium of surface Q – Shear stress at a point which is at a radius ‘r’ 11. The torque transmitted by a solid shaft T= π 16 τD3 2 Marks Q & A