Reuben Hale, P.E.
Ph: (510) 507-1300
The stress on components of a rotating structure are often estimated using strain measurement. For instance, we have instrumented cast fan blades on several occasions with strain gages to look at fatigue and failure issues. The strain measurements help to validate the dynamics and static stress predictions of a computer FEA model of the fan blades. The model subsequently refined, and is then used to estimate the benefits of various design changes.
Fan Blade FEA and Test Data
We use state of the art strain gage instrumentation that is built to withstand many Gs of centripetal acceleration while mounted on the rotating structure. We often use either slip rings, or in some instances, telemetry, to carry the strain signals out to our equipment.
What makes our services so unique is that on every project we are involved with we are aware of the larger picture of the many factors affecting the structural dynamics of the equipment we are working on. Almost always, our level of experience is key to saving our client crucial time and effort.
|Engine/Gen Set of Oil Drilling Vessel||Paper Mill|
For example, while instrumenting and measuring the strains on the cast 8ft fan blades we noticed a subtle structural detail that indicated that the test fixture was poorly mounted to the concrete slab floor. They had used the same mounting procedure for years, but in this case, with this particular new design, with an unusually small clearance between the fan shroud and the tip of the blade, the loss of stiffness between the shroud and floor was critical. It was thought that instead of the blade exploding due to a casting defect, the blade may have contacted the fan shroud and caused the catastrophic failure.
The way the shroud was mounted would cause random variations in the stiffness of the connection of the shroud to the floor every time it was reassembled and confounded future testing results. This would have created frustration for both our client and their customer (not to mention the life threatening danger of the shattered cast aluminum pieces that left fist sized holes in the tin roof of the warehouse – once was enough). If we had focused solely on a set of strain measurements we would have missed this larger, more critical, issue. Thus, while we were hired to provide strain measurements, we also provided a very crucial review of their test setup as part of our work.
- Strain Gage Testing Services Topics Include:
Overview, Rotating Machinery, Medical Device, Power Generation, Electronics-PCBs Semiconductor, Food Industry, Auto Industry