Interim, In Situ Additive Manufacturing Inspection

Additive manufacturing or 3-D printing is a rapidly growing field where solid, objects can be produced layer by layer. This technology will have a significant impact in many areas including industrial manufacturing, medical, architecture, aerospace, and automotive. The advantages of additive manufacturing are reduction in material costs due to near net shape part builds, minimal machining required, computer assisted builds for rapid prototyping, and mass production capability. Traditional thermal nondestructive evaluation (NDE) techniques typically use a stationary heat source such as flash or quartz lamp heating to induce a temperature rise. The defects such as cracks, delamination damage, or voids block the heat flow and therefore cause a change in the transient heat flow response. There are drawbacks to these methods.

Modeling additive manufacturing processes can be difficult due to the scale difference between the active processing point (e.g., a sub-millimeter melt pool) and the part itself. Typically, the tools used to model these processes are either too computationally intensive (due to high physical fidelity or inefficient computations) or are focused solely on either the microscale (e.g., microstructure) or macroscale (e.g., cracks). These pitfalls make the tools unsuitable for fast and efficient evaluations of additive manufacturing build files and parts. Failures in parts made by laser powder bed fusion (L-PBF) often come when there is a lack of fusion or overheating of the metal powder that causes areas of high porosity. AM-PM uses a point field-based method to model L-PBF process conditions from either the build instructions (pre-build) or in situ measurements (during the build). The AM-PM modeling technique has been tested in several builds including a Ti-6Al-4V test article that was divided into 16 parts, each with different build conditions. With AM-PM, calculations are performed faster than similar methods and the technique can be generalized to other additive manufacturing processes. The AM-PM method is at technology readiness level (TRL) 6 (system/subsystem model or prototype demonstration in a relevant environment) and is available for patent licensing.

The technology is a method to increase automation of Additive Manufacturing (AM) through augmentation of the Fused Filament Fabrication (FFF) process. It can significantly increase the speed of 3D printing by automating the removal of printed components from the build platform without the need for additional hardware, which increases printing throughput. The method can also be leveraged to perform automated object testing and characterization. The method includes embedding into the manufacturing instructions methods to fabricate directly onto the build platform an actuator tool, such as a linear spring. The deposition head can be leveraged as a robotic manipulator of the actuator tool to bend, cock, and release the linear spring to strike the target manufactured object and move it off the build platform of the machine they were manufactured on. The ability for an object to 'fly off of the machine that made it' essentially enables automated clearing of the processed build volume. The technology can also be used for testing the AM machine or the feedstock material by successively fabricating prototypes of the manufactured object, and taking measurements from sensors as the actuator strikes the prototype. This provides automated testing for quality control, machine calibration, material origins, and counterfeit detection.

How It Works The scanners operation is based on the principle of Laser Triagulation. The ShuttleSCAN contains an imaging sensor; two lasers mounted on opposite sides of the imaging sensor; and a customized, on-board processor for processing the data from the imaging sensor. The lasers are oriented at a given angle and surface height based on the size of objects being examined. For inspecting small details, such as defects in space shuttle tiles, a scanner is positioned close to the surface. This creates a small field of view but with very high resolution. For scanning larger objects, such as use in a robotic vision application, a scanner can be positioned several feet above the surface. This increases the field of view but results in slightly lower resolution. The laser projects a line on the surface, directly below the imaging sensor. For a perfectly flat surface, this projected line will be straight. As the ShuttleSCAN head moves over the surface, defects or irregularities above and below the surface will cause the line to deviate from perfectly straight. The SPACE processors proprietary algorithms interpret these deviations in real time and build a representation of the defect that is then transmitted to an attached PC for triangulation and 3-D display or printing. Real-time volume calculation of the defect is a capability unique to the ShuttleSCAN system. Why It Is Better The benefits of the ShuttleSCAN 3-D system are very unique in the industry. No other 3-D scanner can offer the combination of speed, resolution, size, power efficiency, and versatility. In addition, ShuttleSCAN can be used as a wireless instrument, unencumbered by cables. Traditional scanning systems make a tradeoff between resolution and speed. ShuttleSCANs onboard SPACE processor eliminates this tradeoff. The system scans at speeds greater than 600,000 points per second, with a resolution smaller than .001". Results of the scan are available in real time, whereas conventional systems scan over the surface, analyze the scanned data, and display the results long after the scan is complete.

This system connects the properties of the guided waves to the phase changes of a composite part. The system measures temperature, strain, and guided waves during cure almost simultaneously. During life-cycle monitoring, it is feasible to use embedded fiber optic sensors for both load monitoring because of the ability to measure strain and damage detection because of the ability to record ultrasonic guided waves. The guided wave system is incorporated directly into standard curing equipment and technique. It has also been tested and works with flat panels as well as complex structures. The technology would be valuable to manufacturers of aircraft parts (fuselage, wing and other sections), marine hull sections, high speed rail sections, automotive parts and perhaps even building parts. One major application that exists presently, is the fabrication of fuselage and wing sections for aircraft where carbon fiber composite sections are used such as Boeing's 787 Dreamliner.