In-Situ Fringe Pattern Profilometry for Feed-Forward Process Control

In Phase I the research team demonstrated a superior in situ profilometry sensor, based on fringe pattern projection, which quickly measures the whole build plate.nbsp; In this data, significant process phenomena are accurately measured and easily identified, such as spreading defects, rogue particles that have been sintered to the partrsquo;s surface, distortion, surface roughness variation, and virtually any geometric feature.nbsp; Of particular importance is the measurement of powder layer condensation and uniformity. This data serves as input to a model that generates feedforward information to adjust process parameters, resulting in better prediction and control of key material properties such as residual stress and density.nbsp;In Phase II the team will further improve the sensor and test the feedforward model.nbsp; After fine-tuning the modelling capability for stress and distortion, mechanical testing will be conducted to validate model performance and determine the effect of defects (measured with the profilometry) on mechanical performance.nbsp; The result will be real-time determination of part quality by a modelling tool that integrates profilometry-detected defects into the performance predictions. This novel data will then be used to feed and validate a fast-feedback look-up table (generated by inverting the feedforward model), for layer-to-layer laser parameter adjustment during builds.nbsp; Next, a new design of the profilometry sensor will be completed to make it very compact (a few inches) so it can easily be added to OEM AM machines.nbsp;nbsp;nbsp; Then the research team will implement a new sensing technique (with the same hardware) to record video-rate, measurements, at nanometer precision, of thermal expansion and shrinking during the melting process, thereby facilitating novel and powerful analysis of residual stress and/or delamination formation.nbsp; Finally, the research team will demonstrate the whole sensor/modelling package on a NASA geometry of interest.