STRESS

Other Chapters

• Q1: Define Force.
  Ans: A force is a push or pull applied on the body. The unit of force is N.
• Q2: Name the types of force.
  Ans: The types of force are as follows:

  • ➔ Direct Force
    • ➔ Tensile Force
    • ➔ Compressive Force
      • ➔ Axial Force
      • ➔ Eccentric Force
  • ➔ Shear Force
• Q3: Define Direct Force.
  Ans: A direct force acts normal(perpendicular i.e at 90 degrees) to the object is called Direct Force.
• Q4: Define Shear Force.
  Ans: A shear force that acts tangent(angle other than 90 degrees) to the object is called Shear Force.
• Q5: Define Axial Force.
  Ans: The force acting at the centroid of an object is called axial force.
• Q6: Define Eccentric Force.
  Ans: The force acting away from the centroid of an object is called eccentric force.
• Q7: Define Tensile Force.
  Ans: A force that produces Tension (Increase in length) is called Tensile Force.
• Q8: Define Compressive Force.
  Ans: A force that produces Compression (Decrease in length) is called Compressive Force.
• Q9: Define Tension.
  Ans: Increase in length is called Tension.
• Q10: Define Compression.
  Ans: Decrease in length is called Compression.
• Q11: Define Stress.
  Ans: Stress is the internal resisting force developed inside a material when an external load is applied.
  
  Formula:
  Stress = Force / Area
• Q12: Name the types of stress.
  Ans: The types are:

  • ➔ Direct Stress
    • ➔ Tensile Stress
    • ➔ Compressive Stress
  • ➔ Shear Stress
• Q13: Define Direct Stress.
  Ans: Direct stress is the stress produced by Direct Force (when a force acts perpendicular to the cross-sectional area of a material).
  
  Formula:
  Direct Stress = Direct Force / Area
• Q14: Define Shear Stress.
  Ans: Shear stress is the stress produced by Shear Force (when a force acts parallel to the surface or cross-section of a material).
  
  Formula:
  Shear Stress = Force / Area
• Q15: Define Tensile Stress.
  Ans: Tensile stress is the stress produced when a material is pulled or stretched by an external force.
  It increases the length of the material.
• Q16: Define Compressive Stress.
  Ans: Compressive stress is the stress produced when a material is compressed or squeezed by an external force.
  It decreases the length of the material.
• Q17: Write down the unit of stress in:
  Ans:

  System	Measuring Unit
  MKS	kg/m2
  CGS	g/cm2
  FPS	lbs/ft2
  SI	N/m2

• Q18: Define Bending Stress.
  Ans: The stress produced by Bending Moment is Bending Stress.
• Q19: Enlist various modes through which forces affect structural members.
  Ans: Some of the modes are:

  1. ➔ Tension
  2. ➔ Compression
  3. ➔ Shearing
  4. ➔ Bending
  5. ➔ Torsion
• Q20: Differentiate between ordinary and pure bending.
  Ans: A bending moment produced by forces that do not form a couple is ordinary Bending.
  The bending moment produced by forces that form a couple is Pure Bending.
• Q21: Define Neutral surface.
  Ans: A neutral surface is the surface of a beam that does not undergo any tension or compression. At this surface, the force and its effects are zero.
• Q22: What do you know about section modulus?
  Ans: The ratio of Moment of Inertia and distance of extreme fibre from the centroidal axis is section modulus.
• Q23: State any two postulates of bending theory.
  Ans: Two points are:

  • ➔ Beam is straight
  • ➔ The material of beam is elastic
  • ➔ Hook’s Law is applicable to the material of beam
• Q24: State bending equation.
  Ans: where
  M = Bending Moment
  I = Moment of Inertia
  E = Young’s Modulus
  R = Radius of Curvature