Practical Applications of Strain Gauges

1. Practical Applications of Strain Gauges c/o Elizabeth Phillips

2. Then & Now: Under Stress • This link is about how measuring stress has changed over the years to the present day. • These strain gauges are use to measure the amount of stress an airplane can handle until it fails. Before strain gauges were invented, people would put sand or themselves on the wing until it broke. "As you push up on a wing, our analysis says it ought to deflect a certain amount, so we measure [with strain gauges] the amount it actually deflects," says Mark Jenks. • Wings need to be strong in order to fly correctly. Testing the amount of strain a material can take allows engineers to find the strongest material for their planes. • This application would best fit into the Civil Engineering Branch • The Sopwith Aviation Company id one of the top airplane manufacturing companies in Britain.

3. Then & Now: Under StressContinued • I didn’t know that before there were strain gauges, people used sand to measure the stress level of an airplane’s wing. • The strain gauge was invented in only 18 years. To me that’s a very short time. THENNOW

4. SmartBridges • In order to keep bridges in good condition, people have put sensors on bridges to monitor the weak points of a bridge. • Many different types of sensors are put on various places on a bridge to get different readings from the bridge. The sensors measure the stress on the bridge so if it becomes abnormal someone can fix the problem. Different sensors measure different things. Photonic sensors measure the strain on bridge cables, thermistors measure the temperature, and vibrating wire strain gauges measure vibrations on the bridge. • These sensors tell us if a bridge gets weak at some points so that they can be fixed before the bridge can break. • This is most useful to civilengineers. • This information would be most useful for bridge maintenance companies

5. Smart Bridges Continued • I found that using sensors on bridges to keep up maintenance was a very smart idea. • The Tsing Ma Bridge in Hong Kong has 350 sensors to measure it.

6. Strain Gauges and Rail Forces • Strain gauges are used to keep rails in good condition. • These strain gauges are put on the rails in a vertical, longitudinal, and lateral positions to measure different forces. The gauges go on the top, bottom, and sides of the rail. Just like the smart bridges, these sensors are used to maintain good conditions to the rails. The train goes over the rails and trigger the sensors. The data is measured and appropriate action is taken to fix the rails if needed. • The gauges are important because it keeps the rail in good condition. • This would be used for civil engineering. • This information would be useful to railroad maintenance workers.

7. Strain Gauges and Rail Forces Continued • I didn’t know it took so many sensors to measure only one side of a rail. • Not only do the sensor help people keep the rail in good condition, it helps keep the rails from breaking by eliminates the effects of any lateral bending that could reduce or exaggerate a strain reading taken on only one side of the rail.

8. Wind Tunnels • Wind tunnels are used on cars to measure streamline, measuring air speed, and many other things. • The strain gauges are connected to the pipe. They give separate channels of information to provide a range of measurements to include drag, lift and down-force for each wheel. • It makes measuring easier for engineers. • Wind tunnels can be used for mechanical engineering. • Car testers would use this to see problems on a car. • Wind tunnels could be used for many things, and you can get

9. Wind Tunnels continued • Wind tunnels could be used for many things. • You can get different types of information from a wind tunnel depending on how you use it.

10. Vehicle Classifications using Strain Gauge • Students in the University of California are trying to identify what type of car is driving on the road using only a strain gauge. • The strain gauges are installed in a bridge deck to measure how much strain is put on the sensor. A car will drive over the gauge and apply strain. The more strain that is put on the sensor, the bigger the vehicle. • The purpose of the sensor is to find a pattern of what types of areas use what cars to classify them, to monitor traffic in different areas, and protect the privacy of transportation users. • Engineers who work with cars like mechanical engineers would fit this experiment best. • This information could be useful to many people such as road companies and companies that provide toll booths.

11. Vehicle Classifications using Strain Gauge Continued • I think the overall concept of this experiment is amazing. I like out it (the experiment) is used for many different things and not just one concept. • I also think its interesting that every vehicle makes a different type of strain signal.

12. Dynos • A strain gauge is attached to a dyno in order to measure torque on an engine. • A dyno is connected to a flywheel or crankshaft and a strain gauge is attached to the frame of the dyno to measure the torque. When the engine starts, the strain gauge measures the spinning wheel and converts it to torque. • The strain gauge makes it much easier to measure torque. • This is most useful to mechanical engineering branch. • Automotive companies could use this information to find out more about their cars.

13. Dynos Continued • 2 interesting things about dynos are 1. being able to use several devices to achieve one certain measurement and 2. finding out that strain gauges for many different things.

14. Order Of Favorites • Smart Bridges • Auto Classifications • Then & Now: Under Stress • Wind Tunnels • Rail forces • Dynos The smart bridges article was my favorite way of using a strain gauge because it showed how a strain gauge can be used in a very important way and it stated that very clearly.