ITM Blog Posts

The Blog Post category contains blog posts associated with ITM’s testing services, LabVIEW programming, Test & Measurement Hardware, Boiler Monitoring Systems, and iTestSystem applications.

ITM Helps Pave Way to Better Asphalt Testing

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Sang-Soo Kim is used to overcoming bumps in the road. After all, his career is centered on developing technology that improves pavement conditions.

The Ohio University researcher and civil engineering associate professor was facing a fast-approaching deadline to prove his novel asphalt testing device was worthy of startup funding from the state of Ohio when he turned to Integrated Test & Measurement (ITM) for help.

The preeminent researcher had a challenge for Chase Petzinger, ITM software engineer. His scratch-built device — essentially an extreme oven/freezer combo that heats or freezes pucks of asphalt material to force expansion or contraction — needed complex hardware and a custom software solution to control signals from the device and ultimately record asphalt cracking data.

“I was extremely happy and impressed with ITM’s technical skills,” said Kim. “I was on a very tight schedule to finish the project in time, and they were very flexible and accommodating to my needs.”

The job required ITM’s team to develop software to record data from National Instruments hardware as well as control and monitor a custom built Watlow Programmable Logic Controller. In addition, the team had to design and build an enclosure that held all the data acquisition equipment and did all the power-cable management signal conditioning.

“So he had the oven shipped to us, and then he showed up with a big box of all the stuff that he had brought,” recalls Petzinger. “He set it down and said, ‘Okay, make this work.’”

Specific sensors and fixtures included GT1000RA LVDT Sensors, NTC-6000 signal conditioners, RDP S7AC signal conditioners and custom-built stainless-steel fixtures. In addition, the data acquisition process required employing a NI cDAQ-9174 Chassis, NI-9216 RTD modules as well as an NI-9209 Voltage Module.

Asphalt Crack Prediction Control Panel

Petzinger explained that he was able to customize the software application using LabVIEW to both collect the data from the sensors inside the oven as well as directly communicate with the device to control start and stop functions as well as the temperature inside.

“I think there were about 50,000 rows in this Excel document of different commands and ways that I could talk to the device,” said Petzinger. “I had to figure out how to use that information and then start from scratch writing a program that would send the commands that the oven could actually interpret.”

Petzinger considers these types of automation and data logging applications a melding of both science and art.

“We were able to create an application to communicate with a unique piece of hardware that we had never seen before,” he said. “if you have your own proprietary oven or switch or machine or something, we’ve worked with unique applications before, and we can do it again.”

Thanks to ITM, Kim not only was able to present his device to the Ohio Department of Development, but it outperformed even his own expectations.

“We wanted to demonstrate this testing device is indeed able to predict low-temperature performance,” he said. “We ran the test with the device that ITM made, and we had one of the best correlations I’ve seen in an asphalt pavement study.” Kim says ITM helped him prove that his device can predict which mixtures of asphalt will crack more accurately than existing tests. And, importantly, it will yield results in a single day where traditional asphalt studies take a week or longer. Next up in his effort to commercialize the unit, Kim intends to publish the results of his work in industry publications, and he’s already seeking a patent.

For more information about this project or other LabVIEW development projects contact Mark Yeager @ (844) 837-8797 x701

Welcome Aboard Zach Strong

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I’m excited to announce that our team is growing with the addition of Zach Strong.  After graduating in May of 2020, Zach recently moved from Co-Op to a full-time engineering technician position. Zach’s primary role as an engineering technician is to assist with industrial monitoring solution installations and field testing applications. In addition to his work in the field, Zach works in our instrumentation lab assembling and testing custom control panel assemblies, installing strain gauges on customer components, and building and testing customer monitoring and measurement systems.

We welcome Zach to our team.  You can read more about our entire team here.

— Vice President of Operations –  Ryan Welker

How to Estimate iTestSystem TDMS Data File Size

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When streaming high speed data over a long period of time it is important to estimate data file size to avoid filling up your drive and also to prevent producing large, unwieldy data files. I usually try to keep file sizes less than one (1) gigabyte (FAT 32 maximum file size is 4 gigabytes) to minimize potential data losses and to make sure data transfers, analysis, and plotting don’t take too long. Whether you are using the free version of iTestSystem to manually control data file size or the paid version to automatically control file size, it is important to estimate your file size before collecting data.

iTestSystem uses the standard binary TDMS file format to stream high speed data to disk. Estimating file size depends on five (5) things.

  1. Header Size (Negligible for large files)
  2. Number of Channels
  3. Data Type Size in Bytes
  4. Sample Rate
  5. Logging Duration

File Size Formula = ((Number of Channels) x (Data Type Size (bytes)) x (Sample Rate (Samples/Second)) x (Logging Duration (Seconds))) + Header Size

TDMS File Size Estimator Spreadsheet

File Size Example: Eight (8) Accelerometer Channels sampled at 2560 Samples/Second are logged as a double (8 Bytes) for 600 seconds to a TDMS data file. Estimated file size = (8 x 8 x 2560 x 600) = 98,304,000 bytes or 96,000 KB (98,304,000 bytes/1024 bytes / KB).

For more information about iTestSystem or file sizes, contact Chase Petzinger @ (844) 837-8797 x704.

Vibration and Strain Gauge Level Report Automation with iTestSystem

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Our test engineers are often called upon to deploy unattended or “black box” data acquisition systems in the field.  These systems are deployed on machinery, vehicles, and industrial processes to constantly record strain and vibration data at sample rates between 100 and 100,000 Hz. That adds up to a lot of data to sift through.

In situations where we are trying to identify system operation outliers or damaging events, we utilize the Automated Analytics application in iTestSystem to limit the amount of data searches required. The Automated Analytics application allows users to analyze, build, and send sensor level reports only when specific vibration and strain limits are exceeded.  Instead of searching through data files, engineers can easily review the report and download relevant data files from deployed systems for further analysis.

This video demonstrates how to build and send vibration and strain reports using Automated Analytics and other iTestSystem tools and applications.

For more information about our iTestSystem or ITM’s testing services, contact Ryan Welker @ (844) 837-8797 x702.

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Download iTestSystem

7 Tips for Estimating Test Engineering Services Costs

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If the COVID-19 pandemic has proven anything, it is that we live in a business climate where efficiency and accuracy have never been more important. In other words, none of us can afford to make costly mistakes.

With that in mind, I’d like to share some tips for you to consider when it comes to this important question: How Do You Estimate Test Engineering Services Costs?

For engineers, testing engineers and managers who find themselves estimating jobs, getting this step right will prove crucial not only to the success of your projects and bottom line, but also to the trust you build with your clients.

Define the project scope of work

The most important requirement is to properly define the project scope of work. This will not only help you determine the necessary hardware, software, and resources required, but it will also help you identify the customer’s expectations and project deliverables. Properly defining the scope of work will help eliminate or minimize overall project time, as it will prevent delays both during the preparation phase and testing phases. Defining the scope of work will require a deep-dive discussion with your client to fully understand their challenges and goals. Remember not to leave vague language in your proposals. In other words, be sure to define who is responsible to provide all that will be needed to fulfill the project. Without a clear definition of the requirements and deliverables, it leaves a lot open for misinterpretation and expectations.

Materials costs are key

With a properly defined scope, we next must determine what, if any, materials we need to procure. These include sensors, DAQ hardware and other installation supplies. Don’t forget to include the amount of time that will be required to prepare all the materials and hardware. Think through such things as what it will take to package the DAQ hardware for any special environmental requirements. Also, be sure to consider the time it will take you to set up the software configuration file and test all the hardware and sensors prior to deployment. 

Onsite costs are relative

We also need to consider the onsite testing requirements and location specifics. Costs can mount quickly to cover general travel and living expenses, particularly when the job will take your team to remote places for extended periods of time. You need to think about daily commutes to and from the facility as well as the cost variance for different geographic locations. Flights, vehicles, hotels and meals are crucial to estimate as accurately as possible, and that’s going to take extra research on your part. Keep in mind that travel costs are NOT one-size-fits-all.

Build in the value of analysis

Some projects require analysis support and some do not. It all depends on the customers’ resources and requirements. We serve customers by providing raw data files and allow them to perform their own analysis, but we also have experience providing a complete turnkey solution including data analysis. This requirement obviously needs to be defined up front in order to accurately estimate the opportunity.

Hidden costs are crucial

You need to consider everything when estimating a project, and this commonly involves “access to the instrumentation areas” for our projects. We typically work on large, complex equipment that sometimes require additional tools and resources to access the sensor locations. This could include manlifts, scissor lifts, cranes, rope access and scaffolding. Since the equipment is quite large, you need to think about the amount of signal cable required and evaluate that against deploying a network of DAQ chassis which may be a cheaper solution than routing all sensors back to a single DAQ system. It will also be key to build in language and costs in your estimates to address unforeseen delays. For example, include factors that lie outside of your team’s control  — resources not being available, no access to equipment, or even poorly performing equipment that will not allow your team to record good data.

All sensors and gauges are NOT created equally

Sensor installation can vary from a couple minutes to a couple hours depending on the application. The same is true of strain gauges. Depending on the testing environment, strain gauges can be installed quickly or become an arduous task. Some applications involve very high temperature and moisture concerns and may also need to survive for long periods of time, which may require a more robust epoxy that requires a heat cure before data can be recorded from the strain gauges. Some applications involve no environmental concern and are only needed for a very short duration. In these cases, the gauges can be installed quickly after surface prep using an industrial type fast curing epoxy.  Similarly, some applications may benefit from using weldable gauges that can simply be tack welded to the specimen. This eliminates any challenges and reduces installation time by using special epoxies. These are typically much more expensive, so you must evaluate the economics of this option. In either case, the surface must be properly prepped (ground, sanded, polished) to the base material to ensure a good bond to the test piece.

Consider variable labor and expense rates

Our labor rates vary by skill level. Senior engineering and programming labor, for example, costs more per hour than our regular engineering and programming labor. Similarly, sending a senior technician will cost more per hour than a technician. Finally, as is common, materials and expenses are estimated at cost plus 10%. Labor Rates Link

For more information about our testing services, contact Ryan Welker @ (844) 837-8797 x702.

Ryan Welker is a 25-year veteran in engineering, procurement and project management. Ryan currently serves as a Vice President of Operations at Integrated Test and Measurement (ITM) in Milford, Ohio. In this role, he oversees the daily operations and monitors all phases of project fulfillment, including customer inquiries, proposal development, scheduling and manpower, employee training, on-site installations, customer follow-up, and support.

Recent News: Ohio University Asphalt Cracking Prediction System Project

Data Acquisition Equipment Rentals

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Do you need software and National Instruments (NI) C-Series hardware to fulfill your testing requirements? During this uncertain time, Integrated Test & Measurement (ITM) is here to support you. We offer various C-Series voltage, strain, vibration, and temperature modules for rent that can be easily configured in our iTestSystem software for you to record and collect data. The rental hardware can be packaged in a ruggedized case for harsh environments. Also, the rental hardware can be set up for unattended testing applications.

For more information about eligibility, equipment availability or to request a quote contact josh.fishback@itestsystem.com

Click Here for more information about equipment rental.

Click Here for more information about our iTestSystem software.

How to Install Weldable Strain Gauges

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weldable gauges

When it comes to measuring structural stresses and load, every application is unique, and sometimes that means using a different solution.  In some cases where strain gauges are applied, it can be advantageous or even necessary to use weldable strain gauges instead of chemical bonding the strain gauges to the specimen.

Since many epoxies used to chemically bond strain gauges require specific heat and pressure for curing, it can be difficult or even impossible to use this method on large or irregular structures.  Weldable strain gauges offer an advantage in this situation as they eliminate the need to clamp and cure any epoxies for bonding. In addition, weldable gauges can be installed in a variety of environments and weather conditions which offers additional advantages over traditionally bonded strain gauges. Although weldable strain gauges are applied differently, they function in much the same way as their bondable counterparts.

To properly install a weldable strain gauge, you will need:

Always remember to have the proper safety equipment on hand, such as eye protection and gloves, as well as any PPE required by your environment.

When installing a weldable strain gauge, you must first prep the area. Unlike bondable gauges, the area does not need to be polished to a fine degree.  Simply degrease the gauge area, sand down any paint, coatings or excess debris and ensuring the area is purely metallic and free of chemicals is enough.  A clean metal surface is important to the welding process.

After the part has been cleaned, you can position the gauge.  Most weldable gauges come marked so you can align the grid properly.  When the gauge is properly aligned, spot weld the gauge on either side of the gauge along the centerlines, to hold it firmly in position and prevent shifting as the gauge is welded further.  Once secure, the gauge should be welded all around the carrier surface, as illustrated below.

 

Weld-Pattern-4

Recap:

  1. Clean the area to be bonded (Remove all paints, coatings, residue and debris until the surface is smooth).
  2. Mark center-lines for the gauge location with scribe and straight edge.
  3. Place the gauge on the part, lining up the center-lines.
  4. Spot weld the gauge on each line, to secure it in place.
  5. Weld the entire perimeter of the gauge in the pattern shown above.

For more information about our strain gauging and testing services, contact Ryan Welker @ (844) 837-8797 x702.

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Strain Gauge Bridge Completion Modules

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350 Ohm Quarter Bridge Strain Completion

Quarter Strain Bridge with Completion Circuit

The most common strain gauges used to quantify the state of stress on a test specimen’s surface, are uniaxial and rosette gauges.  For accurate measurements of stress and strain, these uniaxial and rosette gauges are independently connected as a Wheatstone bridge in a 3-wire quarter-bridge or half-bridge arrangement.

Strain Gauge Installations for Field Testing | Strain Gauge Services | tshirt-Strain Gauge Services Rectangular Rosette | Engineering Data Acquisition Tools: NI-9237 Bridge Input Module

Custom PTO Shaft Strain Gauge Transducer by ITM | Custom Strain Transducer Service | Custom Strain Gauge Measures KitchenAid Shaft Load

Today, most high-end data acquisition equipment manufacturers provide signal conditioning options for collecting data from single strain gauges.  Signal conditioning for strain gauges usually includes circuitry for bridge excitation voltage, quarter and half bridge completion arrangements, and shunt calibration.

What we offer

Are you looking for expert assistance with accurately measuring stress and strain? or, Do you need to rent or buy data acquisition equipment to collect stress and strain data? 

Get In Touch

Sometimes you may need to view or collect data from a single strain gauge using a device that only has analog voltage inputs and no strain signal conditioning.  This was precisely the case when I was working with the HX711 load cell/strain amplifier.  The HX711 requires a full bridge input so I instrumented my test specimens as such.  If I needed to use a single strain gauge with the HX711, I would have had to use an external bridge completion circuit.

What are your options for measuring single strain gauges with a device that only has voltage inputs or full bridge inputs?

Option 1: Buy a commercial off the shelf bridge completion modules.

The list below gives the specifications for some available bridge completion modules.  I plan on adding more completion modules to this list for future reference, so send me any additional completion options.

Strain Gauge Completion Modules
 
Manufacturer NI VPG Campbell Scientific
Model # NI 9926, NI 9945, NI 9944 MR1-10C-129, MR1-350-130, MR1-120-133 4WFBS1K, 4WFBS350, 4WFBS120
Description 3-Wire Quarter Bridge Completion 3-Wire Quarter Bridge Completion 3-Wire Quarter Bridge Completion
Resistance 1000 Ω, 350 Ω, 120 Ω 1000 Ω, 350 Ω, 120 Ω 1000 Ω, 350 Ω, 120 Ω
Strain Gauge Connector Terminal Block Solder Tab Terminal Block
Device Connector RJ50 Solder Tab Pins and Lead Wire

Option 2: Build your own circuit.

If you are building a product or are in the strain business long term, building your own circuit may be a cost effective alternative to the potentially more expensive off the shelf bridge completion option.  I have built a few bridge completion circuits in the past.  Here is a list of things to keep in mind when designing a circuit.

  1. Use high precision, low resistance temperature coefficient resistors
  2. The voltage source used for bridge excitation should be from a stable source like a reference since the output of a Wheatstone bridge is inversely proportional to the excitation voltage Vout/Vex.
  3. Use remote sensing to compensate for errors in excitation voltage from long lead wires
  4. Amplification will increase measurement resolution and improve signal-to-noise ratio
  5. Filter data to remove external, high-frequency noise

For more information about bridge completion or our strain gauging services, contact Ryan Welker @ (844) 837-8797 x701.

Related Links

Strain Gauge Installations for Field Testing

iTestSystem Tip: Strain Gauge Rosette Analysis

Wireless Strain Measurements with iTestSystem, LabVIEW, and Arduino

Ohio University Asphalt Cracking Prediction System Project

Creating XLS files from TDMS Files

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View TDMS files in Excel

TDMS Data file after import into Excel

Precision testing generates precision data. Acquiring, accessing, and analyzing these data files allows engineers and scientists to lower product costs, engineer time-saving solutions, and even save lives. National Instruments (NI) created the Technical Data Management Streaming (TDMS) file format for high performance data streaming and retrieval. This binary file is structured for easier sorting and access of the complex data within the file.

Collect TDMS files with iTestSystem

Are you looking for expert assistance understanding and manipulating TDMS data files? ITM has greatly simplified things with iTestSystem, its free custom engineering software platform that enables you to organize, acquire, view and analyze data. 

 Allow our experts to walk you through TDMS files or point you to our free solutions.

Get In Touch

Before NI standardized on the TDMS data file engineers and scientists had to create their own high-performance file types. The TDMS file format is supported not only by iTestSystem, but also across all NI software.

WHAT HAPPENS WHEN YOU WANT TO SHARE THESE FILES WITH COLLEAGUES WHEN THEY DO NOT HAVE ITESTSYSTEM INSTALLED ON THEIR COMPUTERS?

 

In these instances, it is often easiest to export a TDMS file to a more commonly used file type like Microsoft Excel (XLSX).

NI provides a free program / plug-in that allows users to open TDMS files in Microsoft Excel. This means anyone can convert a TDMS file into an XLSX file and open it in Excel, and once there the file can be easily saved just like any other spreadsheet. Once saved as an Excel file, you can share, open, view and edit it just like any other XLSX file.

HOW DO I GET THE TDMS IMPORTER PROGRAM / PLUG-IN FOR MICROSOFT EXCEL?

If you have installed iTestSystem Engineering Measurement Software, the TDMS Importer program / plug-in for Microsoft Excel is already installed. If not, then you can download the software here: https://www.ni.com/example/27944/en/

Once you have downloaded the NITDMExcel program by following the link and using the built-in installation wizard, you can save TDMS files as XLSX Excel files. To open a TDMS file in Excel, you can simply double-click the TDMS file. If that doesn’t work, you will need to right-click, navigate to “Open With”, and find the NITDMExcel program wherever you installed it on your computer.

TDMS File Right Click Menu

Right click on TDMS file to import file into Excel

Figure1: Right click on a TDMS file to import into Excel.

Each time you open a TDMS file in Excel, it will create a new workbook. Each workbook will have multiple sheets, one for the file properties such as the name of the test, date the data was taken, and more. The other sheet(s) will contain the data points plotted as part of the test, which would normally be used to create graphs in TestView Plus.

Now you can save the Excel and share it just like any other XLS file!

Related Links

Auto-Zero Utility Update
Wireless Strain Measurements with iTestSystem
Strain Gauge Installation for Field Testing

For more information about sharing data, iTestSystem Engineering Measurement Software, or test equipment rental, contact Ryan Welker @ (844) 837-8797 x702.

Testing Services Team Annual Safety Training

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safety meeting

I want to congratulate my colleague Ryan “RJ” Matthews on a job well done as he recently administered ITM’s annual safety training.  RJ did an excellent job presenting the material and addressing questions. His efforts will certainly help us stay focused on our vigilance toward workplace hazards.

For strain gauging or test services, contact Ryan Welker @ ryan.welker@itestsystem.com or ‪(844) 837-8797‬ x702