ChE 361 #2
Home > Flashcards > Print Preview
The flashcards below were created by user
on FreezingBlue Flashcards
. What would you like to do?
Which material criterion should used to minimize the mass for a given beam stiffness?
Suppose the price per kilogram of material is denoted by Cm. Which criterion should be used to minimize the price for a given beam stiffness?
Equation for stiffness
What kind of loading causes buckling to occur?
Which factor from equation Fcrit=(n2pi2EI)/L2 depends on the shape of a structural member and the square of its cross-sectional area?
Which kinds of structural members are most susceptible to buckling?
If the geometry of the beam or plate is held constant, how does the vibrational frequency scale with material properties?
A hard diamond indenter is pressed into the surface of a material with force F, creating a permanent indentation of depth l and area A. Suppose the material has modulus E, shear modulus G, and strength sigma. How is the hardness computed from this test?
According to the text, what is the approximate relationship between hardness and yield strength for many materials?
The tensile strain at fracture is a measure of which property?
Where does the largest shear stress occur in s sample subjected to a tensile load?
Planes inclined at 45 to the tensile load
What drives dislocation glide?
What are four ways to strengthen a metal?
- 1. dispersion of small particles
- 2. introduction of solutes
- 3. reduction of grain size
- 4. plastic deformation
What are four ways to strengthen a polymer?
- reinforcement of fibers like glass
- blending with stronger polymer
How is work-hardening explained?
Dislocations obstruct each other
What is intrinsic strength?
Strong atomic bonds resist dislocation movement
How is solid solution hardening explained?
Solute-generated stresses "roughen" slip planes
How is dispersion strengthening explained?
Precipitates obstruct dislocation movement
What occurs during elastic deformation?
Atomic bonds stretch but do not break
What is annealing?
Heating removes dislocations
What is cold working of a metal?
Plastic deformation without heating
How can work-hardening be reversed?
What causes many materials to yield at stresses far below their ideal strength?
What is an edge dislocation?
An extra half plane of atoms
What is a glide plane?
Plane which a dislocation moves
Identify each of the quantities in following equation:
- Y=correction factor
- sigma=nominal stress
- c=crack length
- E=elastic modulus
- (EGc)1/2=fracture toughness
Which phenomenon does Y(sigma)(pi*c)1/2=(EGc)1/2 describe?
What causes brittle fracture?
long, sharp-tipped cracks
What can happen at the tip of a crack when local stress exceeds the ideal strength?
Crack propagates by cleavage
What can happen at the tip of a crack when local stress exceeds the yield strength?
Plastic deformation that blunts the crack tip
How does ductile fracture occur?
Linking of voids in plastic zone
How can the addition of glass fiers to a polymer matrix crate a tough composite?
Gibers act as crack stoppers
Why are many ductile materials also quite tough?
Energy is consumed by plastic flow
How do cracks start in an uncracked component subject to high-cycle fatigue?
Local plasticity occurs where scratches or section changes concentrate stess
How do cracks start in an uncracked component subject to low-cycle fatigue?
General plasticity roughens the surface
What happens during peening?
Residual surface compressive stresses are introduced
What causes work-hardening?
Dislocations accumulate and hinder each other
What happens during cyclic loading when Kmax=K1c?
Fails by fast fracture
In the context of this course, what is fatigue?
Failure of a structure due to cyclic stress
Which process(es) can cause the formation and slow growth of cracks at loads well below the yield strength?
Which process generally causes final failure in fatigue?
What is the cyclic stress intensity range, delta(K)?
Kmax-Kmin or Y(delta(sigma))(pi*c)1/2
What is the definition of the mean stress?
What is the definition of the stress amplitude?
What is the definition of the cyclic stress range?
What would you like to do?
Home > Flashcards > Print Preview