To determine the yield strength, proportional limit, ultimate strength of steel bars and develop stress-strain relationship.

OBJECT: TO DETERMINE THE YIELD STRENGTH, PROPORTIONAL LIMIT, ULTIMATE STRENGTH OF STEEL BARS AND DEVELOP STRESS-STRAIN RELATIONSHIP.

APPARATUS:

• Steel Bars
• Vernier Caliper
• UTM

THEORY:

1. STRENGTH: The greatest stress that can withstand without failure is called strength.
2. STRESS: It is the internal resistance to applied force or The force per unit area is called stress.
3. STRAIN: It is a change in length per unit its original length is called strain.
4. ELASTICITY: It is the ability of a material to restore its original dimensions after removing the load from it.

1. YIELD STRENGTH OF STEEL BAR: It is the maximum stress that a steel bar can withstand before changing its shape permanently.
2. ULTIMATE STRENGTH OF STEEL BAR: The maximum stress that any material can withstand before failure is called Ultimate Strength.
3. PROPORTIONAL LIMIT: It is the end of the elastic region called proportional limit.

METHODOLOGY:

• For finding the yield strength, ultimate strength, and proportional limit of a steel bar, take a steel bar.
  • With the help of Vernier Caliper, find its diameter to find out the area.
• Put the steel bar in UTM (Universal Testing Machine) find out the yield load of the steel bar and note down the readings.
  • Also, find the ultimate load in UTM.
  • After finding these values, put the values in the formula, and find or calculate its area, ultimate strength, and yield strength steel bar.

OBSERVATIONS:

• Diameter of Steel bar = __________ mm = ________ inches
  
• Area = __________ mm²
  
• Load = __________ N
  
• Ultimate strength of steel bar = ________________ MPa (N/mm²)
  
• Yield Strength = ______________ MPa (N/mm²)
  

CALCULATIONS:

RESULTS: