In-situ digital image correlation and thermal monitoring in directed energy deposition

A method comprising:

• providing a machine vision system including an infrared camera and a stereo pair of imaging cameras for imaging visible light;
• additively manufacturing a component by depositing a material in successive layers in a directed energy deposition process;
• acquiring, during the additively manufacturing step, image frame data of the component based on the output of the machine vision system, the image frame data including a plurality of image frames taken of the component during the directed energy deposition process;
• extracting, from the image frame data, position data of a surface feature of the component as a function of time, wherein the surface feature is internally-facing and becomes obscured during the additive manufacture of the component, and wherein the position data of the internally-facing surface feature includes coordinates in a synthetic reference frame, wherein the synthetic reference frame is a reconstructed reference frame, the position data being extracted based on a natural surface roughness of the surface feature without a speckle pattern being applied to the surface feature, such that the surface feature is identified and tracked by the machine vision system over time;
• and
• determining a strain within the component based on a change in the position data of the internally-facing surface feature over time in the synthetic reference frame.