Civil | Infrastructure

The Civil/Infrastructure category contains blogs related to civil engineering and infrastructure projects.

Machine Failures Caused by Intermittent Damaging Events

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Over the years we have been tasked with identifying the root cause of machine structural failures. In many cases, we can determine the failure mode through strain and vibration testing, order analysis, modal analysis, and operating deflection shape analysis.  What tests can you run when the damaging conditions are intermittent and not easily identified?

In these cases, we like to install a cellular networked temporary data acquisition (DAQ) system that can autonomously log vibration and strain data along with machine status data. We have deployed two types of DAQ systems to collect data remotely.  An interactive system that includes an industrial PC running our iTestSystem software and National Instruments (NI) Compact DAQ hardware and a headless system that utilizes NI Compact RIO hardware.  Our test engineers prefer using the interactive solution for troubleshooting because they can view real-time signal waveforms and collected data files, and then adjust the test parameters accordingly without having to reprogram the hardware.

Rugged Measurement System

Figure 1: Headless networked data acquisition system

When potentially damaging events are identified in the vibration and strain data collected by these systems, it is important to know the machine’s operating status. Collecting the machine status information is just as important as collecting the structural data.  Many machines transmit these operating variables and operating stages over their network/bus.  Recently we have recorded process data from Allen Bradley Control Logix PLCs via Ethernet/IP, mining machine data from a Siemens controller via proprietary TCP/IP protocol, boiler condition data from a DCS via Modbus TCP,  machine pressures from PI historian via the UFL connector (TCP), and vehicle speeds and pressure via CAN.  Fortunately, we were able to use and adapt LabVIEW communication protocol tools to build applications and addons that allow this network tag data to be collected along with structural data.

LabVIEW Modbus to Shared Variable Code

Figure 2: Modbus to Shared Variable Tool

After the data collection phase, our engineers perform statistical analysis on the sensor and status channels in all data files and aggregate the results into a database for searchability. To identify the root cause probabilities, you can process the channel statistics data using your favorite correlation algorithm or application.  The image below shows an example data set containing related sensor data that was processed using a LabVIEW correlation test tool.

LabVIEW Correlation VI

Figure 3: Correlation Test Example vi

Contact Information: For more information about our remote data acquisition service, our LabVIEW development service, or iTestSystem contact:

Mark Yeager – Integrated Test & Measurement (ITM), LLC.  Email: mark.yeager@itestsystem.com or Phone: 1.844.TestSys

iTestSystem Download

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Strain Gauge Installations for Field Testing

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shaft torque sensor

Image1: Shaft torque strain gauge installation example for field testing

Our engineers and technicians have epoxied, soldered and spot welded strain gauges for applications ranging from high temperature exhaust systems to miniature load cell measurements. Every application requires a unique understanding of the strain measurement requirements including installation environment.

If the strain gauge installation is to survive in the field you must plan for the conditions it will undergo. Three important variables that you should account for are temperature range, liquid exposure, and potential impact forces. These variables determine the type of strain gauge, epoxy, solder, wiring, coating, and impact/wear protection to use in the application. The table below shows which variables affect your installation choices.

  Gauge Epoxy Solder Wiring Coating Covering
Temperature  
Liquid Exposure      
Impact Forces      

Table1: Strain gauge installation variables

For more information about ITM’s strain gauging services contact Ryan Welker at email: ryan.welker@itestsystem.com or phone: 1.844.837.8797 x702

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DOT Structural Health Monitoring

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As engineering consultants, it’s the nature of our business for our work to take us out on the open road. It is for this reason that we are proud to support several state Departments of Transportation (DOT) with their structural testing and data acquisition needs.  We travel the very roads, bridges and other major infrastructure that they work so hard to design, build and maintain. 

Over the years, our field-testing experts have provided DOTs with the manpower needed to install and maintain the structural sensors for monitoring bridge and infrastructure usage/health, as well as the custom enclosures that house the precision data acquisition (DAQ) equipment used to process and trend data from the structural sensors.  We are looking for more opportunities to provide DOTs with the manpower and tools needed to keep tabs on our aging infrastructure.  

If you need help or advice on a structural monitoring project, contact Ryan Welker (ryan.welker@itestsystem.com or 1.844.837.8797 x702).  

Building a Modern User Interface in LabVIEW

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When we develop LabVIEW™ applications for our customers, a common request is for a simple, resizable and intuitive user interface (UI) for data visualization.  In these cases, we use a tree control and a subpanel.  This type of UI functions like a tab control that automatically resizes.  The main benefit of using a subpanel is to make your code more modular.

Figure 1: Modern User Interface with a Tree and Sub Panel.

To illustrate the modularity that this type of UI creates, I made an example LabVIEW™ project.  The main VI shown above uses a tree control to switch between a VI containing a graph and a VI containing a table.  I used our multi-queue event architecture for VI information communication messaging.  The image below shows the main VI’s significant functions.

Figure 2: Main VI’s Block Diagram – Significant Functions

The main VI’s functions are listed below.

Functions

  1. Initialize queues and events and then generate initialize event.
  2. Initialize tree and add tree items.
  3. When a user selects an item in the tree, generate data and then send it to the subpanel VI.
  4. Receive SubPanel Ready event from a subpanel VI and then insert the VI into the subpanel.
  5. Destroy queues and unregister for events.

In this example the subpanel VIs are very simple.  They populate an indicator (table or graph) and then generate a SubPanel Ready Event.  The two (2) subpanel VIs and block diagrams are shown below.

Figure 3: SubPanel VIs: Graph.vi and Table.vi

Contact Information: For more information on this example or our LabVIEW development service contact:

Mark Yeager – Integrated Test & Measurement (ITM), LLC.  Email: mark.yeager@itestsystem.com or Phone: 1.844.TestSys

iTestSystem Download

ITM Strain Gauging Services

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Garrison Dam

Quantifying stress, strain and force within a structure using real world strain gauge measurements is commonly used to verify FEA models and estimate a component’s fatigue life.  Our engineers and technicians have planned and implemented challenging strain gauge installations for our customers around the globe.  Information from these strain gauge installations has allowed our customers to validate their designs and improve their product’s reliability.

For more information about these applications and our strain gauging services, contact Ryan Welker via email ryan.welker@itestsystem.com or phone: (844) 837-8797 x702