Vibration and Acoustical Testing/Engineering Services

Vibration and Acoustical Testing/Engineering Services may offer any or all of the following:

1. Vibration Testing and Troubleshooting — involves the science taking measurements in order to gain in-depth knowledge of the dynamic motion of specific products or equipment. They are normally performed to determine resonant frequencies or problem frequencies at which the specific product or equipment is vulnerable to, such as external or internal vibration or acoustic noise sources.

Components and equipment often analyzed include:

• Pumps, Compressors, and Turbines
• Motor and Generator Skids
• Machinery Rotor Drivetrains
• Mounting Structures and Foundations
• Piping

2. Modal Analysis Testing — used to determine resonant frequencies and mode shapes of the tested structure or object. It's also performed to confirm finite-element analysis data. Modal analysis and finite-element modeling are usually performed in concurrently.

Modal testing involves the measurement and analysis of input forces and corresponding response vibrations when a structural system is dynamically excited with either an electromagnetic shaker or a hammer. A low-level dynamic force (usually less than 50 lbs) is applied at one location (driving point) on the structure. The location of the driving point and the measurement points are carefully chosen to identify all modes of vibration of the structure in the desired frequency range. The transfer functions between the driving force and dynamic responses are computed during the measurements. The measured data are saved on a personal computer for subsequent analysis.

3. Finite Element Analysis and Modeling — usually an inexpensive methood of designing a prototype. Although an empirical testing (e.g. modal-analysis testing and dynamic-response measurements) has to be performed to verify the results, a FEA model usually reliable enough to account for how a structure or a component will behave under stress. Objects as large as a building structure and as small as a component of a measurement device can be modeled with good accuracy and with reasonable assumptions.

4. Acoustical Testing — may use:

• a sensitive metrology tool
• an acoustic impulse test to estimate the sound absorption in a room

Applications: reduction of factory noise; reduction of auto/vehicle noise; control acoustics in office buildings, concert halls, recording studios

5. Source identification measurements — conducted when threre are suspected issues with a specific source of vibration, acoustic noise, and /or low frequency stray magnetic fields for a SEM (scanning-electron microscope) or an optical inspection-tool with an imaging problem. Tests for vibration, acoustic noise, and low frequency stray magnetic fields are performed to determine the nature of the problem.

6. Vibration Isolation — an example of its use is in evaluating passive or active isolation tables used in the semiconductor industry.

7. Vibration Monitoring — Often performed on operating (running, in-production) equipment and requires a system of hardware and software that may include:

• Multiple spectrum analyzers including a 7 channel Pulse system
• Multi-channel Data Aquisition System
• Oscillisocpe
• Accelerometers, Pressure Transducers (Dynamic and Static), Sensors, Microphones, Hydrophones and Proximity Probes

Vibration testing services normally perform a battery of tests in accordance with published standards from organizations such as:

• Underwriters Laboratories (UL)
• European Community (CE)
• International Standards Organization (ISO)

Next: Vibrations from Mechanical Equipment

Prev: Mechanical System Noise and Vibrations

top of page   Home