Elastic and Plastic Behaviour

• What are the two types of deformations materials can undergo?

  Elastic and plastic deformation
• What happens to an object during elastic deformation when the load is removed?

  It returns to its original shape
• How is elastic deformation represented on a graph?

  In the elastic region of the graph

  
• What characterizes plastic deformation?

  The material is permanently deformed
• What occurs when the load is removed after plastic deformation?

  The object will not return to its original shape
• What is the elastic limit?

  The point beyond which plastic behaviour occurs
• What are the two types of deformation that materials can undergo?

  Elastic deformation and plastic deformation
• What happens to the object when it undergoes elastic deformation?

  The object will return to its original shape when the load is removed
• What happens to the object when it undergoes plastic deformation?

  The object will be permanently deformed when the load is removed
• Where is the elastic limit on a Force-Extension graph?

  The elastic limit is the point where the material transitions from elastic to plastic behaviour

  
• What is the difference between the elastic region and the plastic region on a Force-Extension graph?

  In the elastic region, the extension is proportional to the force, while in the plastic region the extension is no longer proportional to the force

  
• What is the difference between brittle and ductile materials on a stress-strain or force-extension graph?

  Brittle materials have a straight line through the origin with no curved region, while ductile materials have a straight line through the origin that then curves towards the x-axis

  
• If a metal wire is extended to the point just before fracture, and then the masses are removed, what will the resulting graph look like?

  The graph will have the same gradient as before, but the y-intercept will not be at the origin due to the permanent plastic deformation
• What are the key differences between elastic and plastic deformation?

  • Elastic deformation: Object returns to original shape when load is removed
  • Plastic deformation: Object is permanently deformed when load is removed
  • Elastic deformation occurs below the elastic limit
  • Plastic deformation occurs above the elastic limit
  • Elastic deformation is represented by a straight line on a Force-Extension graph
  • Plastic deformation is represented by a curved line on a Force-Extension graph
• What are the key differences between brittle and ductile materials on a stress-strain or force-extension graph?

  • Brittle materials:
  • Represented by a straight line through the origin with no curved region
  • Break with little elastic and insignificant plastic deformation
  • Ductile materials:
  • Represented by a straight line through the origin that then curves towards the x-axis
  • Stretch into a new shape before breaking

  
• What is the elastic limit on a Force-Extension graph?

  The point where the material transitions from elastic to plastic behaviour

  
• If a material exhibits plastic deformation, how should you describe it instead of saying it "does not obey Hooke's law"?

  The material is permanently deformed