The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Oct. 19, 1993
Filed:
Jun. 17, 1991
John H Varterasian, Livonia, MI (US);
Francis H Chen, Rochester Hills, MI (US);
Wolfgang Kiel, Warren, MI (US);
Kent E Brittin, Lockport, NY (US);
Patrick D Quinn, Rochester Hills, MI (US);
Kenneth J Zielesch, Fraser, MI (US);
Kurt A Tesnow, Sterling Heights, MI (US);
Thomas H Worswick, Mount Clemens, MI (US);
General Motors Corporation, Detroit, MI (US);
Abstract
Nondestructive testing of heat exchangers (12), such as a radiator, measures the percentage of good bonds between air centers and cooling tubes based on natural or resonant frequencies of the exchanger (12). The exchanger (12) is excited by an audio speaker (38) and measured for a first natural frequency in the center thereof by an accelerometer (44). The natural frequency is indicative of the percentage of good bonds in the center portion of the exchanger (12) based on the stiffness thereof. The audio speaker (38) is moved to an antinode of a higher frequency mode to measure a second natural frequency indicating the percentage of bonds at the edges and corners thereof. The resonant frequencies are compared to standards to determine the actual percentage of good bonds.