VM-AM-MECH-004

VM-AM-MECH-004
Additive Manufacture of 4-Inch Double Cantilever with Supports Using Ti-6Al-4V

Overview

Reference:Model and experimental results courtesy of University of Pittsburgh
Material:Ti-6Al-4V
Solver(s):Additive in Mechanical
Physics/Modes:Linked Transient Thermal - Static Structural
Supports Included:Yes
Platform:Windows only

Test Case

Perform a simulation of a Laser Powder Bed Fusion (L-PBF) additive manufacturing process of a 4-inch beam with cantilevered ends with supports printed with Ti-6Al-4V titanium alloy.

Find the Z-direction distortion along an edge of the part after the supports have been removed and compare results to measurements taken of the built part.

Figure 191: Built Part

Built Part

Figure 192: Schematic

Schematic

Analysis Assumptions and Modeling Notes

Material properties are used for EOS Ti-6Al-4V. The simulation includes a build step, a cooldown step, and support removal steps. Heat is applied at a constant temperature (35°C) to the underside of the base plate during the build step. Room-temperature convection is applied to that same surface during the cooldown step. Throughout the simulation the base plate is anchored by a fixed boundary condition on the underside of the plate. Supports are removed first from the left side (all at once) and then from the right side (all at once). Measurements are made after the supports have been removed. Deflection results were measured along the centerline of the top surface. For comparison purposes, the minimum deformation was set to zero for both the experimental and simulation data. The analysis is performed using a Cartesian mesh.

Build SettingsBuild ConditionsCooldown Conditions
Deposition/Powder Layer Thickness = 0.03 mmPreheat Temperature = 35°CRoom Temperature = 22°C
Hatch Spacing = 0.14 mmGas Temperature = 35°CGas Temperature = 22°C
Scan Speed = 1200 mm/secPowder Temperature = 35°CPowder Temperature = 22°C
Dwell Time = 9 secGas Convection Coeff = 0.00001 W/mm2°CGas Convection Coeff = 0.00001 W/mm2°C
Dwell Time Multiple = 5Powder Convection Coeff = 0.00001 W/mm2°CPowder Convection Coeff = 0.00001 W/mm2°C
Number of heat sources = 1Powder Property Factor = 0.01Powder Property factor = 0.01
Mesh and Material Settings
Element size = 0.7 mm Cartesian mesh
Projection Factor = 0.7

Results Comparison

The distortion in the Z direction follows the trend of the measured results. Despite the symmetrical geometry, distortion is unsymmetrical. The amount of distortion at each end is affected by the support removal sequence.

ResultsTargetMechanicalError (%)
Z Deformation (Positive X End)0.66160.66720.8464
Z Deformation (Negative X End)1.3911.3906-0.0288

Figure 193: Comparison of Predicted Z Deflection Along Edge to Measured Data

Comparison of Predicted Z Deflection Along Edge to Measured Data