
Welcome to Test Devices' Data Acquisition & Reduction Page

Spin Testing Data Acquisition and Reduction

Overview

Being a testing services company, Test Devices understands that test data are the most valuable product we provide to customers. Testing can be expensive and affect customer schedules, which makes repeating tests due to inadequately recorded data undesirable. In the case of destructive testing, where the part itself will not survive, test data may the only information available to make decisions that affect product design, cost, reliability, and safety. Therefore, we know it is imperative to acquire reliable test data for every test, - this is why customers come to us.

With this in mind, we have continually upgraded our data acquisition capability to provide customers with test data in the most useful formats. Strip chart recorders, long an industry standard, have been replaced by modern PC-based data acquisition systems designed by Test Devices specifically for use with spin test systems. Test data recorded digitally has several advantages over traditional paper records, for example: enables manipulation from several perspectives for more sophisticated analysis, requires less storage space, and retains it accuracy in storage, immediately available on CD-ROM, and is transmittable via e-mail to off-site engineers for review.

Data Recorded

As can be viewed on other pages of our website, Test Devices provides customers with a full line of spin test services, including: proof (over-speed), burst, low cycle fatigue, high cycle fatigue, radial growth, and strain survey (instrumented) testing. This variety of tests requires different kinds of data be recorded. Routine proof and burst tests only require the speed and vibration data be recorded, while high cycle fatigue and strain survey tests necessitate recording strain gage data as well. Temperature (elevated or cryogenic) can also be added as another data component recorded for all of the tests listed above.

Recording Capability

Several kinds of spin tests (low cycle fatigue, high cycle fatigue, radial growth, strain survey) offered at TDI also require that multiple data channels be recorded simultaneously. To accommodate the need for recording multiple channels of data, Test Devices employs a data acquisition system capable of recording 64 channels of data. Test Devices can monitor and record data at sample rates ranging from several readings per second for temperature signals to several thousand per second for passage of air foils from a bladed rotor assembly. The data acquisition system has a sample rate of 1 million samples per second and a high signal to noise ratio, producing very clear data. Test Devices can also record data with wide band tape recorders which are useful as backup media and replaying data recorded in analog format.

TDI’s data acquisition systems have been used successfully to record temperature, strain, vibration, and rotor growth data during a multitude of tests.

Data Reduction

For many spin tests, particularly long duration and instrumented tests, the number of data points recorded is extremely large. Besides the availability of the complete raw data, Test Devices also provides translation and reduction services. Translation takes the native sensor output and converts it into the units of interest against a calibrated curve. The millivolt output of a thermocouple, for example, will be converted into temperature. Reduction of the data, on the other hand, puts the data in to formats (time, X-Y plots, Fast Fourier Transform (FFT), zooming, spreadsheet, graphs) which summarize important events and also facilitate further analysis and review by the customer. All signals are converted to engineering units and can be transferred in to special units specified by the customer. The reduction process includes filtering the raw data to produce only the useful and pertinent data, providing the customer with a succinct review of the test

Some Data Reduction is done in real time to provide the operator with pertinent information during the test, allowing for live adjustment of the test protocol. However, post test data processing is critical in understanding events which may have taken place in hundredths of a second.

A copy of the raw test data accompanies the reduced data in the final report. Therefore, the customer can analyze the actual data points as desired. Additionally, test data (raw and reduced) are archived at Test Devices for future review and analysis by the customer.

Examples

Below are examples of test data taken from various spin tests. The data below have been reduced to graphical format.

Proof Test Data

Figure 1
Data taken for a standard over-speed (proof) test.
All spin test data, even routine over-speed tests, are recorded
on our custom data acquisition system.

LCF Test Data