Stress/Strain

Question 1

What is tensile/compressive stress?

Answer 1

-The force applied divided by the cross-sectional area, or Pa
-Compressive is negative, tension is positive

Question 2

What is tensile/compressive strain?

Answer 2

-Defined as the change in length, divided by the original length of the material, a ratio or percentage
-Compressive is negative, tension if positive

Question 3

What is the breaking stress?

Answer 3

-The effect of stress starts puling atoms apart from one another
-The stress becomes so great, the atoms separate completely and the material breaks
-The UTS or Ultimate Tensile Stress, is the maximum stress the material can withstand
-Depends on conditions like temperature so is taken into consideration when designing a structure

Question 4

What is elastic strain energy?

Answer 4

-Work is done to stretch a material
-Before the elastic limit, the work done is stored as elastic strain energy
-The area under a force-extension and stress-strain graph
-Can be done linear or not

Question 5

What is the young modulus?

Answer 5

-When you apply a lot, it experiences stress and strain
-Below the limit of proportionality, the stress divided by strain is a constant, known as the young modulus
-Is used to measure stiffness and used to withstand sufficient forces

Question 6

How can you find the young modulus?

Answer 6

-The gradient of a stress-strain graph
-Is a straight line provided Hooke’s law is obeyed