Advanced engineering in fields such as aerospace and automotive requires high quality information about the structural loads which the designs are subjected to. One way to obtain this information is by measuring the small displacements (strain) in the structure when it is loaded. The strain can be measured with strain gauges that are mounted to the structure. By calibrating the structure with a known load the transfer function between the loads and the strain can be calculated. By inverting this matrix the load can then later be calculated from the strain measured in service.
The locations of the strain gauges have a large impact on the accuracy of the results. Currently, most companies use “rules of thumb” and engineers’ best guesses to select the locations for the strain gauges. For complex structures that are exposed to several different loads (vehicles for example), it is difficult to intuitively choose good positions for the strain gauges.
With the LW Finder software, the best locations can be found and the standard deviation of the error for each load case is also calculated before any physical test is done. This is very important to judge if the structure is good enough to use as a load transducer or if the structure needs to be modified.
LW Finder uses the result from a Finite Element Analysis of the structure to find the best combination of strain gauge placement. The different load cases can be weighted so that the given number of gauges is placed to get the minimum error for one or more of the load cases.
LW Finder optimizes the error caused by noise and crosstalk. It looks for placement with high strains which reduces the noise and placements that is sensitive for only one load case which reduces the crosstalk.