SYSTEM COMBINING LASER ABLATION WITH ULTRASOUND INSPECTION OF PARTS

• US 20190331646A1
• Filed: 04/30/2018
• Published: 10/31/2019
• Est. Priority Date: 04/30/2018
• Status: Active Grant

• Current Assignee: The Boeing Co.
• Original Assignee: The Boeing Co.
• Inventors: George, Panagiotis Emanuel, Tracey, Ashley C., Tat, Hong Hue
• Granted Patent: US 10,724,997 B2
• Time in Patent Office: Days
• CPC Class Codes: B23K 2101/18 Sheet panels
• CPC Class Codes: B23K 2103/172 wherein at least one of the layers is non-metallic
• CPC Class Codes: B23K 26/0006 taking account of the properties of the material involved B23K26/32, B23K26/40 take precedence
• CPC Class Codes: B23K 26/03 Observing, e.g. monitoring, the workpiece
• CPC Class Codes: B23K 26/0622 by shaping pulses
• CPC Class Codes: B23K 26/082 Scanning systems, i.e. devices involving movement of the laser beam relative to the laser head
• CPC Class Codes: B23K 26/0853 Devices involving movement of the workpiece in at least in two axial directions, e.g. in a plane
• CPC Class Codes: B23K 26/352 for surface treatment
• CPC Class Codes: B23K 26/36 Removing material B23K26/55, B23K26/57 take precedence
• CPC Class Codes: B23K 26/362 Laser etching
• CPC Class Codes: B23K 26/402 involving non-metallic material, e.g. isolators
• CPC Class Codes: B23K 31/125 Weld quality monitoring
• CPC Class Codes: G01N 2291/0231 Composite or layered materials
• CPC Class Codes: G01N 2291/0234 Metals, e.g. steel
• CPC Class Codes: G01N 2291/0258 Structural degradation, e.g. fatigue of composites, ageing of oils
• CPC Class Codes: G01N 2291/0289 Internal structure, e.g. defects, grain size, texture
• CPC Class Codes: G01N 2291/2694 Wings or other aircraft parts
• CPC Class Codes: G01N 29/04 Analysing solids using acoustic emission techniques G01N29/14
• CPC Class Codes: G01N 29/2418 using optoacoustic interaction with the material, e.g. laser radiation, photoacoustics photoacoustic cells G01N21/1702; measuring characteristics of vibrations by using radiation-sensitive means G01H9/00; acousto-optical conversion techniques for short-range imaging G01S15/8965; sound-producing devices using laser bundle G10K15/046
• CPC Class Codes: G01N 29/265 by moving the sensor relative to a stationary material
• CPC Class Codes: G01N 29/4436 : with a reference signal amplitude comparison G01N29/48

Abstract

A system and method combine ablation of a surface of a part with inspection of the internal integrity of the part. A laser may direct an ablative laser pulse at the surface of the part sufficient to remove a portion of material from the part surface and to cause the part to produce an ultrasound waveform. A positioning system may provide relative movement of the ablative laser pulse and the part for application of a series of ablative laser pulses at a series of locations over an area of the surface of the part. An ultrasonic detection device may couple to the part to receive the ultrasound waveform and transmit it to a part inspection system that has stored a set of reference waveforms in a control computer. The system compares the ultrasound waveform to one or more of the reference waveforms to detect and characterize anomalies in the part.

Claims

1. A system for preparing an area of a surface of a part formed of a composite material and for inspecting a structural integrity of the part, the system comprising:

a. a laser ablation system for directing an ablative laser pulse at the surface of the part to remove a portion of the composite material adjacent to the surface of the part and to cause the part to produce an ultrasound waveform;

b. a relative-positioning system coupled to one or both of the part and the laser ablation system, wherein the relative-positioning system provides for adjusting a relative position of the part and the ablative laser pulse over a set of locations distributed across the area of the part;

c. an ultrasound testing system including a transducer to detect the ultrasound waveform produced by the part; and

d. a processor for receiving the ultrasound waveform and comparing the ultrasound waveform at one or more locations in the set of locations to a baseline waveform.

2. The system of claim 1, further wherein the transducer is fixed in position relative to the laser ablation system.

3. The system of claim 1, wherein the ultrasound testing system further includes a positioning system for moving the transducer relative to the part.

4. The system of claim 1, wherein the relative-positioning system further includes an attitude control mechanism for adjusting an attitude of the laser ablation system relative to the part.

5. The system of claim 1, wherein the transducer is coupled to the surface of the part where the ablative laser pulse is directed.

6. The system of claim 1, wherein the transducer is coupled to a second surface of the part, the second surface located opposite the surface where the ablative laser pulse is directed.

7. The system of claim 1, wherein the portion removed from the surface of the part is between about 3 microns and about 9 microns in depth.

8. The system of claim 1, wherein the portion removed from the surface of the part is at least about 3 microns in depth.

9. The system of claim 1 for use in preparing the surface of the part wherein the composite material of the part includes multiple layers of a fiber material embedded in a matrix material, and wherein the laser ablation system directs the ablative laser pulse at the surface of the part sufficient to remove a portion of the matrix material.

10. The system of claim 1 for use in preparing the surface of the part wherein the composite material of the part includes multiple layers of a fiber material embedded in a matrix material, and wherein the laser ablation system directs the ablative laser pulse at the surface of the part sufficient to remove the matrix material down to the fiber material.

11. A system for combined preparation of a surface of a composite structure and inspection for an internal integrity of the composite structure, the system comprising:

a. a fixture for holding the composite structure;

b. a laser ablation system for directing an ablative laser pulse at the surface of the composite structure to remove a portion of composite material from the surface of the composite structure and to cause the composite structure to produce an ultrasound waveform;

c. a positioning system coupled to at least one of the laser ablation system and the fixture for positioning of the composite structure relative to the laser ablation system;

d. an ultrasonic detection device for coupling to the composite structure to receive the ultrasound waveform; and

e. a control computer coupled to the laser ablation system, the positioning system, and the ultrasonic detection device for directing a series of ablative laser pulses at a series of locations over the surface of the composite structure and receiving the ultrasound waveform from the composite structure after each pulse, the control computer receiving a set of ultrasound waveforms.

12. The system of claim 11 wherein the control computer includes a baseline waveform that the control computer compares to the set of ultrasound waveforms.

13. The system of claim 12 further wherein the control computer identifies any locations on the composite structure where the ultrasound waveform is anomalous as compared to the baseline waveform.

14. The system of claim 11 wherein the control computer includes plural baseline waveforms including at least one baseline waveform representative of a known conforming part and at least one baseline waveform representative of a known defective part, wherein the control computer compares the baseline waveform representative of a known conforming part to the set of ultrasound waveforms, and wherein the control computer compares the baseline waveform representative of a known defective part to at least a portion of the set of ultrasound waveforms.

15. A method for preparing an area of a surface of a part formed of a composite material and for inspecting a structural integrity of the part, the method comprising the steps of:

a. providing a laser ablation system for directing an ablative laser pulse at the surface of the part to remove a portion of the composite material from the surface of the part and to cause the part to produce an ultrasound waveform;

b. providing a system for relative positioning of the part and the ablative laser pulse;

c. providing an ultrasound testing system including a transducer to detect the ultrasound waveform produced by the part;

d. positioning the part relative to the ablative laser pulse at a location in the area of the part;

e. directing the ablative laser pulse at the location in the area of the part;

f. receiving in the ultrasound testing system the ultrasound waveform caused by the ablative laser pulse;

g. comparing the ultrasound waveform at the location to a baseline waveform; and

h. repeating, at a set of locations distributed across the area of the part, the steps of positioning the part relative to the ablative laser pulse, directing the ablative laser pulse, receiving the ultrasound waveform, and comparing the ultrasound waveform.

16. The method of claim 15 further wherein the step of comparing the ultrasound waveform to the baseline waveform is carried out by the ultrasound testing system.

17. The method of claim 15 further wherein the step of positioning the part relative to the ablative laser pulse is carried out by moving the part.

18. The method of claim 15 further wherein the step of positioning the part relative to the ablative laser pulse is carried out by changing a targeting of the ablative laser pulse.

19. The method of claim 15 further wherein the steps of receiving the ultrasound waveform and comparing the ultrasound waveform are performed for substantially all of the ablative laser pulses.

20. The method of claim 15 further wherein the steps of receiving the ultrasound waveform and comparing the ultrasound waveform are performed only for a subset of the ablative laser pulses.