Reuben Hale, P.E.
Ph: (510) 507-1300
When a very complex structure is thought to be the cause of vibration to an adjacent structure, there are often many interconnecting elements/systems that are suspect. To further complicate the problem, there are also often multiple suspected sources of the disturbance. We will often start by forming a number of likely hypothesis based on our initial analysis of the system and discussions with the client. We will then suggest a test plan to prove or disprove these hypothesise by making measurements of the system response to ambient, and known stimulus.
Multiple Sources & Load Paths
Strain, or stretch, in a structural element is one way to show that force is being transmitted along a particular piece of the structure. We can then ask the questions:
- Does the force transmitted through a structural member have the expected magnitude needed to explain the resulting response on the receiving structure?
- Does the frequency content of the force match the disturbance frequency on the receiving structure?
These are some of the questions we can answer using strain gage testing to prove of disprove a hypothesis. This often involves crawling around on beams in dark corners of a noisy plant to install strain gages in hard to reach places. Or climbing up 200ft of ladders to test an oil filter mount in a Wind Turbine. Often, the ability to positively identify a force transmission path makes this effort worthwhile.
For example, we were called in to help identify the cause of vibration to the control room of a newly constructed 120 Mega-Watt power plant. The vibration in the control room was so bad that the control personnel could not read the monitors. There was also a stairway that was unusable due to high vibration levels, and a few stalls in the mens bathroom that were not usable as well due to the uncomfortable vibration levels. The use of strain gage testing at this power plant was a key part of this interesting project. Using the strain gage measurements we were able to quantify the forces transmitted between the isolated turbine pedestal and the surrounding building. Through a combination of this strain gage testing and our dynamic testing and analysis we were able to zero in on a surprisingly simple solution. We give a brief description of this work under this link:
- Strain Gage Testing Services Topics Include:
Overview, Rotating Machinery, Medical Device, Power Generation, Electronics-PCBs Semiconductor, Food Industry, Auto Industry