Detecting cracks and defects in cast parts with LabVIEW

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September 2000 Data Acquisition & Telemetry

Cracks and defects in parts used in a variety of applications ranging from mission-critical aerospace and automotive parts to household fixtures can cause catastrophic failures when the parts are stressed during use. Using National Instruments LabVIEW software and hardware, Image Therm Engineering and Indigo Systems created an innovative solution, ThermoSoniX (patent pending), to find these cracks and defects quickly and accurately. Image Therm and Indigo Systems plan to upgrade ThermoSoniX to LabVIEW 6i because of the improved execution performance, including increased speed, smaller memory footprint and tighter integration of data acquisition (DAQ) and image acquisition (IMAQ) available in LabVIEW 6i.

ThermoSoniX works by ultrasonically stimulating the workpiece and monitoring it with infrared imaging to identify cracks and defects in ferrous and nonferrous metals, ceramics and composite parts. When exposed to ultrasonic energy, cracks or defects in a part can vibrate differentially inducing localised heating. An Indigo infrared camera is used to effectively image this induced heating which is typically only a fraction of a degree. By combining LabVIEW with IMAQ and DAQ, ThermoSoniX analyses the synchronised digital images acquired from the Indigo infrared camera through an IMAQ board and analog signals from the integrated ultrasonic excitation source through a DAQ board, then automatically produces intuitive images that highlight the cracks and defects in the part.

ThermoSoniX delivers considerably improved part inspection performance by replacing many of the expensive, time-consuming and environmentally unfriendly techniques currently used in the nondestructive testing (NDT) market. ThermoSoniX can also detect compression cracks in parts which may be difficult or impossible to detect with other NDT techniques, including radiography. "We used LabVIEW to develop ThermoSoniX because with it we could quickly prototype and build the final application, easily synchronise IMAQ and DAQ and effectively use the IMAQ and DAQ virtual instrument libraries provided by National Instruments," said Dino Farina, President of Image Therm Engineering.

The portable ThermoSoniX Test Station is sold by Indigo Systems as a fully integrated NI-based system with either a PC or PXI chassis.

"With measurement intelligence - the integration of measurement hardware, sensors and software to automatically recognise and configure available measurement components - LabVIEW 6i delivers functions we have looked forward to for years. We are much more efficient with the new array of processing functions. In addition, the ability to create dynamic link libraries (DLLs) and shared libraries with LabVIEW 6i adds plenty of flexibility and power to our applications programming. And the new data acquisition waveform data type simplifies our block diagram programming and data flow tremendously," said Farina.

National Instruments

(011) 787 0473

[email protected]

www.westplex.co.za

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Data Acquisition & Telemetry

Detecting cracks and defects in cast parts with LabVIEW

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