Western Electric Company, Inc.

Sotirios John Vahaviolos

Min-Chung Jon

Mansoor A Saifi

Charles Andrew Keskimaki

A beam lead device which has been thermocompressively bonded to a substrate is non-destructively tested to determine the strength thereof by directing a short burst of air at the device and detecting the Stress Wave Emission (SWE) signals emanating from the bond site subsequent to said burst of air. The SWE signals are then processed to determine the strength of the adhesion bond.

Methods and apparatus for the non-destructive testing of bonded articles

Signals emanating from a weld are detected during the post weld period and excursions of the detected signal above a predetermined threshold are counted. Simultaneously, an envelope of the signal is developed and excursions thereof above the threshold are also counted. A ratio of the signal excursion count to the envelope excursion count is formed. The ratio so formed is compared to known ranges of ratio values to determine whether the detected signal is mechanical noise or a stress wave emission signal.

Method and apparatus for distinguishing stress wave emissions from

A plurality of window comparators and voltage controlled oscillators are arranged to receive analog input signals which are converted to output frequencies that are linearly proportional to the analog signals over a substantially infinite amplitude range.

Voltage controlled oscillator

Spot welds are evaluated using stress-wave emission techniques by measuring the stress-wave energy emitted from the weld area during n time intervals of the weld cycle, where n.gtoreq.4. Each of the time intervals corresponds to a different aspect of the weld cycle such as, for example, the initiation of heating, the separate solid-to-liquid phase transformation in each of the articles being welded, material combination within the weld nugget, cooling stresses occurring during resolidification, and post-weld cracking. The energy values obtained for each of the time interval can be compared with predetermined acceptable energy value ranges for corresponding ones of the intervals and/or compared with predetermined ratio values between two or more of the obtained interval values to determine the quality of a weld.

Method and apparatus for evaluating welds using stress-wave emission

The strength of an adhesion bond can be determined using stress-wave emission techniques. One method measures the stress-wave emitted from the bonding area during the compression phase of the formation of the bond and compares this measurement with a predetermined substantially linear relationship between the emitted stress-wave energy and the strength of the adhesion bond. For more accuracy, a second method measures the stress-wave energy during both the compression phase and a pressure-relief interval, determines the difference between the two measurements, and compares the difference value with the substantially linear relationship. An alternative to the second method subtracts a predetermined threshold value from the pressure-relief interval measurement, reduces the compression phase measurement by the excess determined by said subtraction step, and compares the reduced compression phase measurement with the predetermined substantially linear relationship to determine the strengh of the bond.

Method and apparatus for the real-time, non-destructive evaluation of

Continuous welds are monitored by detecting and processing stress-wave signals emitted from the moving weld area to provide an indication of both the weld energy supplied to the weld area by the welding apparatus, and the development of microcracks in the cooling weld area. According to the present invention, the detected stress-wave signals emitted from the weld area are amplified and filtered to provide excellent signal-to-noise ratios and then applied to either one, or both, of (a) an RMS voltmeter, and (b) a spectrum analyzer to provide an indication of the weld energy supplied to the weld area and the development of cracks in the cooling weld area.

Method and apparatus for the real-time monitoring of a continuous weld

Apparatus is disclosed for detecting and measuring peak-to-peak values in an electrical input signal, the signal comprising at least one positive-going and one negative-going peak and can include waveforms characterized by short duration and fast rise time pulses. In operation, one of the at least one input signal peaks is referenced to a predetermined d.c. voltage level, such as, for example, 0 volts d.c., and an electrical output signal is generated which is representative of the magnitude of the input signal with respect to the predetermined d.c. voltage level. The output signal is generated by electrical circuitry capable of accurately tracking fast rise time pulses and then stretching the other unreferenced at least one peaks to prevent decay thereof.

Apparatus for detecting and measuring peak-to-peak values in electrical

Spot welds are evaluated using stress-wave emission techniques by detecting and measuring the stress waves emitted from a weld area during a first solid-to-liquid phase transformation period and a second liquid-to-solid phase transformation period of the weld. The stress waves emitted during the first transformation period provide an indication of the weld nugget size, while the stress waves emitted during the second transformation period provides an indication of the amount of post-weld cracking in the weld area. By subtracting the stress-wave energy measured during the second transformation period from the stress-wave energy measured during the first transformation period, an indication of the strength of the weld is obtained.

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East Windsor Township, NJ, United States of America

Sotirios John Vahaviolos