Mechanics of Materials Flashcards
what is the definition of strong?
The amount of force per cross-sectional area something can withstand before breaking (N/m^2) or Pascals (Pa)
What is the definition of tough?
The ability of a material to withstand scratching and deformation. Diamond is very high in this property
What is the definition of brittle?
If a material is cracked, the crack will grow very quickly and the thing breaks without deforming first. Opposite of tough
What is the definition of Dense?
The mass per volume of material measured in kg/m^3 and described by the equation p = m/v
What is the definition of Hard?
The amount of energy per cross-sectional area something can withstand before breaking. Measured in J/m^2
What is the definition of Stiff?
If you put a force on this material, this describes how much it extends, compresses, shears or twists. Eg, the spring constant K = F/x is described by the modulus of elasticity where E = stress/strain
What is Hooke’s Law
The strain in a solid is proportional to the applied stress within the elastic limit of that solid.
What is Elastic behaviour?
As long as the load is below the limit of proportionality, the material will return to its original length when the force is removed
What does the spring constant tell you? Equation
How many newtons of force it would take to extend a spring by 1 meter
k = F / x
Spring constant = Force / extension
What does the area under a force/extension graph represent?
Energy stored as Elastic when extended
E = 1/2 Fx
What is Hysteresis?
the stretching of a tendon
What is the equation for stress?
delta = F / A
stress = Force / Cross Sectional Area
What is the definition of strain?
epsilon = x / L
strain = change in length / original length
What is yield stress?
where the material stops behaving elastically and begins behaving plastically
What is the ultimate tensile strength?
The maximum amount of energy required to deform the material
