Measuring and testing – Vibration – Resonance – frequency – or amplitude study
Reexamination Certificate
1999-03-12
2001-03-13
Williams, Hezron (Department: 2856)
Measuring and testing
Vibration
Resonance, frequency, or amplitude study
C073S587000, C073S602000, C700S030000, C700S031000, C702S036000
Reexamination Certificate
active
06199431
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to the field of resonant ultrasound spectroscopy (RUS) and more particularly to the use of the data generated by RUS for developing testing criteria and pattern analysis; testing of production parts using pattern analysis; and use during maintenance procedures of archival resonant frequency records and pattern analysis for subsequent comparison testing of each individual part compared to its unique archived previous measurements, as identified by serial number.
2. The Prior Art
Resonant ultrasound testing is known in the prior art as exemplified by U.S. Pat. No. 4,976,148 Migliori et al., U.S. Pat. No. 5,062,296 Migliori et al., U.S. Pat. No. 5,351,543 Migliori et al. U.S. Pat. No. 5,355,731 Dixon et al., U.S. Pat. No. 5,495,763 Rhodes et al., U.S. Pat. No. 5,408,880 Rhodes et al., and U.S. Pat. No. 5,425,272 Rhodes et al., plus recent issued cases, all of which are incorporated therein by reference.
U.S. Pat. No. 5,355,731 teaches measurement of sphericity utilizing resonant ultrasound spectroscopy. In this disclosure, a first set of calculations are used to determine resonant frequencies as the functions of Poisson's ratio where the spherical objects have an ideal dimension. Next, calculations are made to determine a set of resonant frequencies where there is a deviation from dimensions of the ideal object dimensions. Then a production object is measured by resonant ultrasound (RUS), and is compared to the calculated values to determine the deviation from the ideal object dimensions.
Migliori U.S. Pat. No. 4,976,148 teaches the use of resonant ultrasound spectroscopy (RUS) for determination of elastic constants of a sample.
BRIEF SUMMARY OF THE INVENTION
The prior art includes strain gauge devices embedded in parts which can indicate deformation when compared to historical baseline data. This can indicate that the metal has been deformed or yielded. It can also measure a strain, and if measurements are made while the structure is being stressed in a precise quantitative manner, it will permit the inference of a change in elastic modulus due to fatigue, overload, heat damage, or some other factor. In other words, connecting a resistance measurement instrument to an aircraft landing gear with a built-in strain gauge will tell only if the metal has already yielded, i.e., permanently stretched. This is considered to be a metal failure unless there is a known load change placed upon the assembly causing the strain.
In this invention, Applicant provides for a complete method of resonant inspection for periodic maintenance which encompasses the entire life of a product or component. Applicant initially provides for measurement of resonant mode frequencies of a prototype to obtain empirical data, measurement of resonant mode frequencies of at least one production part upon completion of manufacture of a production part, pattern analysis of those resonant mode frequencies, comparison of resonant mode frequencies of at least one production part to the prototype resonant mode frequencies to obtain comparative data, and subsequent inspecting of at least one production part at maintenance intervals by comparing its resonant mode frequencies and a pattern analysis of these frequencies to resonant mode frequencies and pattern analysis data recorded in memory at the time the part was produced. The inspection measurements and pattern analysis results are added to the archived record for that serial number part, at each inspection interval. Archived records can then be compared to subsequent inspection measurement results to establish a history of part changes or deterioration.
This invention is particularly advantageous for use in testing components of high value and significant consequences in the event of a failure, such as aircraft turbine rotors and disks. Testing is upon initial manufacture, and for subsequent periodic maintenance. The use of resonant ultrasound spectroscopy (RUS) measurements with this method permits detection of flaws which develop within periodic maintenance intervals, or as they develop in the components during the intervening periods of operation. It is possible to detect stress failures and metal structure precursors to cracks in parts which may occur internally even prior to the development of internal or external cracks. This technique, therefore, leads to detection of potentially catastrophic failures in aircraft landing gear, aircraft rotors and disks long before such failure may occur, and before it can be detected by other non-destructive means. This method also provides an archived record of objective measurements and pattern analysis results relating to the structural integrity of each component at the time of the inspection.
REFERENCES:
patent: 4799387 (1989-01-01), Matsuo
patent: 4976148 (1990-12-01), Migliori et al.
patent: 4984173 (1991-01-01), Imam et al.
patent: 5062296 (1991-11-01), Migliori
patent: 5327358 (1994-07-01), Stubbs
patent: 5351543 (1994-10-01), Migliori et al.
patent: 5355731 (1994-10-01), Dixon et al.
patent: 5408880 (1995-04-01), Rhodes et al.
patent: 5425272 (1995-06-01), Rhodes et al.
patent: 5493511 (1996-02-01), Wincheski et al.
patent: 5495763 (1996-03-01), Rhodes et al.
patent: 5533399 (1996-07-01), Gibson et al.
patent: 5686667 (1997-11-01), McCollum et al.
patent: 5886263 (1999-03-01), Nath et al.
Nath Robert H
Saxon Jay G
Schwarz James J
Quasar International, Inc.
Saint-Surin Jacques
Snider Ronald R.
Snider & Associates
Williams Hezron
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