Solid Mechanics Flashcards
What is strength?
The resistance to failure
What is stiffness?
the resistance to deformation
How is normal stress denoted and calculated?
What are the units?
by sigma o~
Force/ Area
Units N/m^2 or Pa
How is normal strain denoted and calculated?
What are its units
by epsilon curved E
change in L/ L
no units
What’s poisson’s ratio?
mechanical properties are independent of direction. when a material is stretched in one direction there is a contraction in the particular direction.
v= -epsilon y / epsilon x
v= lateral strain/longitudinal strain
What’s hooke’s law?
The relationship between engineering stress and strain. Elastic behaviour
How to calculate young’s modulus
stress/strain
what’s does the proportionality limit on a stress strain graph mean?
up to that point, stress is proportional to strain (hooke’s law)
how would you find the elastic modulus of a material from a stress strain graph?
the gradient while hooke’s law is maintained (the straight line)
what is the yield point (yield stress)
the lowest stress at which permanent deformation can be measured
what effects strength but not stiffness of a material?
alloying, heat treating, manufacturing processes
What is the equation to calculate thermal displacement?
alpha (coefficient of thermal expansion) x change in T x original length
what does statically determinate mean?
we can calculate reaction forces, internal forces and stresses from statics alone
what does statically indeterminate mean?
calculations of reaction forces, internal forces and stresses cannot be obtained by statics alone
