Module 3.4 Flashcards
Brittle
A brittle object is one that shows very little strain before reaching its breaking stress
Compression
The result of two coplanar forces acting into an object Compression usually results in a reduction in the length of the object
Compressive deformation
The changing of an object’s shape due to compressive forces
Ductile
A material is ductile if it can undergo very large extensions without failure. Ductile materials can be stretched into wires
Elastic deformation
If a material deforms with elastic behavior, it will return to its original shape when the deforming forces are removed. The object will not be permanently deformed
Elastic potential energy
The energy stored in an object when it is stretched. It is equal to the work done to stretch the object can be determined from the area under a force-extension graph
Extension
The increase of an object’s length
Force-extension graph
A plot showing how an object extends as the force applied increases. For an elastic object, the gradient should be linear up to the limit of proportionality. The gradient gives the spring constant
Hooke’s law
the extension of an elastic object will be directly proportional to the force applied to it up to the objects limit of proportionality
Plastic deformation
If a material deforms with plastic behavior, it will not return to its original shape when the deforming forces are removed. The object will be permanently deformed
Polymeric
A material made from polymers
Spring constant
The constant of proportionality for the extension of a spring under a force. The higher the spring constant, the greater the force needed to achieve a given extension
Strain
The ratio of an object’s extension to its original length. It is a ratio of two lengths and so has no unit
Stress
The amount of force acting per unit area. Its unit is Pascal (Pa)
Tensile deformation
The changing of a object’s shape due to tensile forces
Ultimate tensile strength
The max stress that an object can withstand before fracture occurs
Youngs modulus
The ratio of stress to strain for a given material. Its unit is the Pascal (Pa)
Hooke’s law
Hooke’s law states that for a material within its elastic limit, the force
applied is directly proportional to the extension of the material
when does Hooks law not work
Once the elastic limit of the
material is reached, Hooke’s law is no longer obeyed and the material will not return to its
original shape.
what does the area under a force extension graph mean
work done
Tensile strain
Tensile strain is defined as the extension or compression of a material per unit of its original
length. It has no unit, and is sometimes written as a percentage.
