For problems that are rather complicated and have hardware available, we can often simply instrument the actual part and subject it to all types of loading right in the laboratory. This is a very direct, economical approach and always succeeds in conveying the integrity of the new design to management and others. We can also create the physical model to test right in our prototype machine shop, if needed.
Instrumentation options include strain gages, deflection gages, and photoelasticity. Each has its own strengths and each is inexpensive to apply.
Strain gages are bonded on resistive elements that are already calibrated to give strain values after wiring up. They give complete information on the strain field at a specific location. We can also measure residual stress and strain using strain gages.
Deflection gages are for overall deflection data. These can be individual dials or transducers wired right into our data acquisition system.
Photoelasticity is fascinating to observe and provides a “full-field” solution, enabling the engineer to have a quantitative map of the entire stress field for the part in question. This is very powerful, especially for new parts, or for old part being loaded in new ways.