ABSTRACT
Clarence W. de Silva
Measurement and associated experimental techniques play a significant role in the practice of vibration.
Academic exposure to vibration instrumentation usually arises in laboratories, in the context of learning,
training, and research. In vibration practice, perhaps the most important task of instrumentation is the
measurement or sensing of vibration. Vibration sensing is useful in the following applications:
1. Design and development of a product
2. Testing (screening) of a finished product for quality assurance
3. Qualification of a good-quality product to determine its suitability for a specific application
4. Mechanical aging of a product prior to carrying out a test program
5. Exploratory testing of a product to determine its dynamic characteristics such as resonances,
mode shapes, and even a complete dynamic model
6. Vibration monitoring for performance evaluation
7. Control and suppression of vibration
Figure 1.1 indicates a procedure typical of experimental vibration, highlighting the essential
instrumentation. Vibrations are generated in a device, the test object, in response to some excitation. In
some experimental procedures, primarily in vibration testing (see Figure 1.1), the excitation signal has
to be generated in a signal generator in accordance with some requirement (specification), and applied to
the object through an exciter after amplification and conditioning. In some other situations, primarily in
performance monitoring and vibration control, the excitations are generated as an integral part of the
operating environment of the vibrating object and may originate either within the object (e.g., engine
excitations in an automobile) or in the environment with which the object interacts during operation
(e.g., road disturbances on an automobile). Sensors are needed to measure vibrations in the test object. In
particular, a control sensor is used to check whether the specified excitation is applied to the object,
and one or more response sensors may be used to measure the resulting vibrations at key locations of
the object.
