CAMT Material Properties & Characterization

Question 1

Which material property describes the ratio of stress to strain in the elastic region of a stress-strain curve?

Accepted Answer

Modulus of elasticity (Young's modulus)

Answer

Yield strength

Answer

Ultimate tensile strength

Answer

Fracture toughness

Question 2

In additive manufacturing, anisotropy of mechanical properties is most commonly caused by:

Accepted Answer

Layered build direction creating directional microstructure

Answer

Incorrect bed temperature

Answer

Excessive infill density

Answer

High ambient humidity during printing

Question 3

Which test is used to measure the resistance of a material's surface to permanent indentation?

Accepted Answer

Hardness test

Answer

Charpy impact test

Answer

Tensile test

Answer

Fatigue test

Question 4

Porosity in metal AM parts is most problematic because it:

Accepted Answer

Acts as a stress concentrator that reduces fatigue life

Answer

Increases the part weight

Answer

Improves surface finish

Answer

Increases thermal conductivity

Question 5

Which phenomenon occurs when a polymer AM material absorbs moisture from the environment, affecting print quality?

Accepted Answer

Hygroscopy

Answer

Oxidation

Answer

Crystallization

Answer

Delamination

Question 6

The glass transition temperature (Tg) of a polymer is important in AM because it defines:

Accepted Answer

The temperature above which the material becomes rubbery and loses rigidity

Answer

The melting point where the material becomes fully liquid

Answer

The optimal bed temperature for all polymers

Answer

The temperature at which crystallization begins

Question 7

In powder bed fusion (PBF) of metals, the powder particle size distribution affects:

Accepted Answer

Powder flowability, packing density, and surface finish of the part

Answer

Only the color of the final part

Answer

The speed of the laser only

Answer

The electrical conductivity of the machine