In many applications requiring force, load, pressure, or torque measurements, you may not have the ability to install a standard off-the-shelf sensor due to space considerations or costly modifications to your existing structure. This white paper provides an overview of the most effective way to use a strain gage to turn an existing load-carrying part or support into a sensor.
There are different categories of strain gages to help meet many applications. A single linear strain gage is what we call a quarter bridge that can be used in a number of different ways. The T-rosette type has two measuring grids or what we call a ½ bridge were each grid is arranged at a 90° offset from each other, enabling measurement of axial strain and Poisson’s effect on the same strain gage backing. This technique can be used in bending/shear beams, column types or for measuring torque.
There are many applications for strain gages. Depending on the measurements to be taken different strain gage patterns can be used. Some application examples are shown in Figure 1. In medical applications, strain gages are used to sense occlusion in infusion pumps as pressure, torque in medical robots, and force in all types of medical devices that may require the gages or sensors to survive hundreds of autoclave cycles.
As farm equipment has become “smarter,” strain gage sensors are used in all types of applications such as downforce sensors for seeding machines and torque for autonomous tractors. For cranes and off-highway vehicles, there are many safety aspects that need to be accounted for as far as overturn or over lift protection. Today’s industrial robots are moving into all fields of manufacturing and require sensors for precise force feedback loops. It all comes back to different sensors that can measure the mechanical changes and how you adapt a sensor for the most accurate measurement.