Method and devices to construct artificial inline defects to calibrate inspection hardware on automated fiber placement systems

Inventors

JUAREZ, Peter D.GREGORY, ELIZABETH D.

Assignees

National Aeronautics and Space Administration NASA

Publication Number

US-11685129-B2

Publication Date

2023-06-27

Expiration Date

2040-12-04

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Abstract

Systems, methods, and devices are provided for the creation of predictable and accurate defects in a fiber tow of an Automated Fiber Placement (AFP) process, with such artificial defects being useful to support calibration of an in situ inspection system used in the AFP process. Various embodiments include methods for creating such artificial defects that support calibration of an in situ inspection system of an AFP system or process. Various embodiments may also include a defect stencils for an AFP system or process.

Core Innovation

The invention provides systems, methods, and devices for creating predictable and accurate artificial defects in a fiber tow during an Automated Fiber Placement (AFP) process. These artificial defects are designed to support the calibration of an in situ inspection system used in the AFP process. The methods enable the creation of gap and/or overlap defects with known size, geometry, and location within an AFP course or system during the composite part layup.

The problem addressed is that AFP manufacturing is prone to defects such as tow overlaps and gaps caused by tow slippage, which affect the structural integrity of the finished parts. Although in situ inspection systems have been developed to detect these defects during manufacturing, there currently exists no method to create accurate, predictable defects within an active AFP process to calibrate these inspection systems. Existing calibration methods only apply to out-of-process inspections or rely on unpredictable defects identified post-layup, neither of which enable real-time calibration during layup.

The invention overcomes this by providing a method that involves selecting an artificial defect size (length and width), using a defect stencil with a cut path corresponding to the selected defect dimensions, and creating the defect by cutting tow material using the stencil before the tow is aligned to form a course. For overlap defects, the cut portion is reapplied to another tow to create a controlled overlap, while the removal creates a corresponding gap in the first tow. The defect stencil can securely hold the tow and define precise cut paths to achieve exact defect geometry. These artificial defects are indistinguishable from real defects to the inspection system, enabling accurate calibration or benchmarking of inspection precision during the AFP process.

Claims Coverage

The patent includes five independent claims covering methods and devices related to creating artificial defects in fiber tows within an AFP system to calibrate in situ inspection systems.

Method for creating artificial defects with selected size using defect stencils

A method comprising selecting a length and width for an artificial defect, selecting a defect stencil with a cut path corresponding to these dimensions, and creating the artificial defect by cutting a portion of tow material using the stencil before the tow is aligned to form a course in an AFP system.

Method for creating artificial gap and overlap defects with tow material manipulation

A method involving selecting length and width for gap and overlap defects, cutting a portion of a first tow using a defect stencil to create the gap, and applying the cut portion to a second tow to form the overlap defect. The method also includes depositing these tows in the AFP system and imaging them for defect detection by an in situ inspection system.

Defect stencil comprising a two-part structure holding tow material and defining a cut path

A defect stencil with a stencil top and stencil base, where the base has a first opening forming a cut path. When placed together with a tow in between, the stencil securely holds the tow and allows cutting it along the defined cut path.

Defect stencil with openings for blade insertion

The stencil top includes a second opening aligned with the base opening for inserting a blade to cut the tow along the cut path when the stencil parts are assembled.

Defect stencil with integrated blade cutting feature

The stencil top includes one or more blades configured to align with the base opening and cut the tow along the cut path when placed together, enabling simultaneous clamping and cutting.

Overall, the independent claims cover methods for creating precise artificial gap and overlap defects using selectable defect stencils and the construction of defect stencils that secure tow material and define accurate cut paths to facilitate the creation of such defects for in situ inspection system calibration in AFP processes.

Stated Advantages

Enables creating predictable and accurate artificial defects during AFP layup to support in situ inspection system calibration.

Allows calibration of inspection systems with defects of known size, geometry, and location improving inspection precision.

Artificial defects behave like real defects during the build, enabling realistic testing and observation of stacking defect effects.

Provides a controllable method for artificial defect creation which can be incorporated into industry standards for certifying inspection systems.

Documented Applications

Calibration and precision benchmarking of in situ inspection systems used in automated fiber placement manufacturing processes.

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