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The Challenge 

A leading metal alloy manufacturer uses tensiometer testing to validate alloy property consistencies across production  

facilities and for research purposes. The legacy system was FORTRAN-based, using a plotter. The drawbacks of this system  are sensor limitations, lengthy configuration times, and cumbersome operational and management procedures. The logging,  analysis and conversion from the load cell and extensiometers are tedious, manual procedures.  

The Solution 

Data Science Automation has developed a LabVIEW based solution to incorporate data acquisition, control, and  sophisticated analysis that incorporate RS-232 and GPIB interfaces to Instron and Daytronic devices. 

Abstract  

The purpose of this solution is to increase efficiency by decreasing the setup time for each test, increase reliability in the  results by reducing the chance for human error, and to incorporate a user interface that is easy to use.  

User Interface 

The LabVIEW tab control is a flexible and powerful user interface tool that permits the operator to sequentially execute the  test procedures for the desired material. A load cell calibration file exists for all load cells and extensometers, and contain  necessary data for configuring the device used for testing in the right manner. As seen in Figure 1 the user will select a load  cell.  

Figure 1 – Load Cell Select

Figure 2 – Load Cell Calibration 

The next process, shown in Figure 2, is to use the proper configuration for the load cell selected. This process is simplified to  avoid erroneous data resulting from incorrect load cell configurations. This familiar and simple process is used for  longitudinal and transverse extensiometer selection, calibration and configuration, and a few other setup procedures. During  test execution, data display is available as shown in Figure 3. Each test configuration/process can be stored and retrieved for  subsequent use. This will greatly improved the efficiency of the testing process. 

Figure 3 – Test Executed 

Analysis Testing 

After each test, a raw data file (illustrated in Figure 4) is generated to display the values from all devices in the system. This  data file contains data such as sample #, time of sample, load cell reading (lbs), and extensometer readings from a transverse  and longitudinal device. The header of this file is all of the setup information for the test. 

Figure 4 – Output File

Once a data file is created the analysis can be executed. In Figure 5 an example of analysis shows the relationship between  load and strain over a period of time. ASTM standards and proprietary parametric analyses were applied to derive physical  properties such as Young’s Modulus, Poisson’s ratio, yield point, ultimate strength, fracture point, stress, strain, strain rate,  etc.. 

Figure 5 – Linear Fit Analysis 

Conclusion 

The versatile NI-based system has the necessary flexibility to supports both Instron and less expensive third-party sensors  with equal ease, reducing their dependence on one sensor vendor.