Читать книгу Metal Additive Manufacturing - Ehsan Toyserkani - Страница 14

αThermal diffusivityαtCoefficient of thermal expansionβAbsorption factorβAbsorption factorβpPowder particles’ absorbed coefficientβwSubstrate laser power absorptivityγSurface tensionγNet electron beam energy (Chapter 5)γESpecific surface energyγSLSolid–liquid interfacial free energyγSVSolid–vapor interfacial energyγLVLiquid–vapor interfacial energyShear rateΓTorque of electrical motors in FDMΓSurface function (Chapter 10)δSolid/liquid interface thicknessδDirac delta function (Chapter 6)εTotal strainεcCooling rateεtEmissivityεMMechanical strainsεTThermal strainsεpEquivalent plastic stressεVacuum permittivityεmMechanical strainεthThermal strain∑Covariance matrixηDynamic viscosityηPowder catchment efficiency (wherever it refers to throughout chapters)ηNumerical damping coefficient for OCM (Chapter 10)ηLearning rate (Chapter 11)ηeAbsorption efficiency for electron beamηdDynamic viscosityηpPowder catchment efficiencyθRepresenting different angles based on figuresθWetting angle (Chapter 2)θFar‐field divergence angle (Chapter 3)θDimensionless temperature in numerical models (Chapter 7)θjetAngle between powder jet and substrateθdDynamic wetting angleθeqSteady‐state angleΘDimensionless temp in analytical modelsλWavelengthλLagrange multiplier (Chapter 10)λnRoots of zero‐order Bessel function of its first kindμViscosityμMembership function (Chapter 11)υFrequency (Chapter 3)υKinematic viscosityρDensityρbDensity of binderρpbPowder bed densityρcDensity of melted powder alloyρsDensity of substrate materialρsPacking density of the pores (Chapter 6)σStefan–Boltzmann constantσCovariance (Chapter 11)σcCharge densityσijElastic stressτThermal time constantτcDimensionless capillary timeϕDifferent label for angles as indicated in the associated figures ϕPowder bed porosityϕShape factorΦInterpolation function (Chapter 10)ϕ(x, y)Level‐set equationϕtapTapped porosityϕ(t)Rate of heat liberation in a continuous point sourceØAngle of incidenceΨStrain energyωSpinning speedωRelaxation factor (Chapter 11)ωiStrength of anisotropyωrAngular velocity of the actuating motorΩSubstrate surfaces or melt pool boundary and material domain