Fundamentals of Additive Manufacturing Technologies

A: A mainly affects the green state surface and wouldn't propagate cracks hours later. B raises modulus but doesn't explain rapid crazing when solvents are present. C leads to delayed mass change and warpage rather than sharp cracks. D matches solvent-assisted crack initiation in highly crosslinked SLA resins exposed to acetone vapour.

A: A ignores that recoating sets the pace once layer count explodes. B drops the layer-by-layer overhead that dominates SLS builds. C underestimates because coupon intuition misses volumetric scaling. D follows first principles on layer count and cycle time, landing in the right decade even before heat soak penalties.

A: A would show field-wide distortion tied to galvo position, not just edges. B leaves a repeating pattern everywhere the hatch runs. C gives macroscopic curl and warpage rather than fine ripples. D explains localized density variation where the blade loses support at the perimeter.

A: A trades fatigue strength for thermal conductivity and doesn't survive hot cyclic duty. B brings corrosion and density penalties not aligned with the environment. C is sensitive to oxygen content which degrades fatigue life. D leverages vacuum processing to control interstitials and protect high-cycle fatigue.

A: A would show first-layer scarring and early failure, not mid-build peel. B creates elephant foot but usually improves adhesion. C causes immediate corner lift from layer one. D allows accumulated shrinkage stresses to overcome the brim later in the build.

A: A misses the infill reduction entirely. B slips a decimal and treats it like a billet. C drops the mass of skins and ribs that add up. D walks the volume and density logic to a reasonable figure without overfitting.

A: A is slow indoors and shows surface chalking first. B needs sustained heat well above service conditions. C would leave surface pitting or swelling. D explains humidity-driven changes in modulus and toughness common to polyamides.

A: A produces random rounded pores not tied to tracks. B leaves smooth, spherical voids often isolated. C causes sporadic defects unrelated to scan strategy. D matches elongated voids along scan lines where melt pools never coalesced.

A: A ignores the weak interface that dominates compliance. B hides worst-case direction under arithmetic comfort. C imports assumptions from molded parts that don't hold here. D gives a fast, defensible check that respects anisotropy under deadline pressure.