Vibration measurement instrumentation

Vibration Measurements Instruments Blow with clean air Dry out... 

ISO 8041, Human Response to Vibration—Measuring Instrumentation, International Organization for Standardization, Geneva, 1990. 

All purchased vibration probes, transducers, and oscillator-demodulators shall be in use during the test. If vibration probes are not fnmished by the vendor or if the purchased probes are not compatible with shop readout facilities, shop probes and readouts that meet the accuracy requirements of API Standard 670 shall be used. The vibration measured with this instrumentation shall be the basis for acceptance or rejection of the pump (see 2.8.3.7 and 2.8.3.8). 

Noise and vibration measurements are made with microphones and accelerometers. Sometimes, sophisticated instruments like laser vibrometers are used for NVH work. Common noise fixes include cutting slots and/or chamfers on the brake pads and linings, the application of constrained layer damping noise insulators to the back of the brake pad shoe plates, and detuning the resonant frequency of mechanical brake corner components. 

Cold drawn specimens of nylon 6 have recently been investigated by Owen and Ward who measured static moduli between — 110 C and -t-20°C, and dynamic tan d between — 70°C and -l- 110 C in a vibrating reed instrument. As can be seen from Fig. 15 the pattern of anisotropy changes with temperature, there being a minimum in o and 90, near room temperature, around the draw ratios at which X-ray diffraction indicates a transformation from an form to a more stable y form. These structural changes, and the changes responsible for the rise in the temperature of the a relaxation with orientation, prevented a detailed understanding of the mechanical deformation processes. 

The Namtre Viscotiner (vibrating sphere) is a simple device, easily placed in the flow line, and easy to clean. However, the measurement one obtains is dependent on the flow rate past the vibrating sphere, and the number obtained is at best an oscillatory parameter, possibly the loss modulus, G", which for the materials usually being measured, cannot necessarily be correlated with off-tine measurements (the same is true for the Bendix vibrating reed instrument and the many others of this kind). However, it is rarely the case that the output signal is resolved into its elastic and viscous components. 

In order to determine the viscoelastic properties of silicone gel materials, vibrational measurement techniques are used. The principle of vibrational measurement techniques involves determining die viscoelastic quantities by observing the responding mechanical behavior when cyclic deformation is applied repeatedly. Dynamic viscoelastic property measurements are performed with a dynamic mechanical spectrometer such as the RDA-II from Rheometrics. This instrument measures the complex modulus G and loss factor tan S from the torque measured by the transducer equipped at the upper portion of the sample chamber when shear deformation is applied to the sample at a specified shear strain and frequency from the actuator at the bottom of the sample chamber. 

Photonics Tech Briefs (targets design engineers who sp>ecify photonics products, covering optics, optical design software, laser systems, cameras and inspection systems, sensors/detectors, test/measurement instruments, positioning equipment, vibration control and fibre optics)... 

Other sources of heat in-flows include mechanical vibrations, sloshing during transport, eddy current heating and Joule heating of measuring instruments. 

The Q and ft) dependence of neutron scattering structure factors contains infonnation on the geometry, amplitudes, and time scales of all the motions in which the scatterers participate that are resolved by the instrument. Motions that are slow relative to the time scale of the measurement give rise to a 8-function elastic peak at ft) = 0, whereas diffusive motions lead to quasielastic broadening of the central peak and vibrational motions attenuate the intensity of the spectrum. It is useful to express the structure factors in a form that permits the contributions from vibrational and diffusive motions to be isolated. Assuming that vibrational and diffusive motions are decoupled, we can write the measured structure factor as... 

Fourier transform infrared (FTIR) analyzers can be used for industrial applications and m situ measurements in addition to conventional laboratory use. Industrial instruments are transportable, rugged and relatively simple to calibrate and operate. They are capable of analyzing many gas components and determining their concentrations, practically continuously. FTIR analyzers are based on the spectra characterization of infrared light absorbed by transitions in vibrational and rotational energy levels of heteroatomic molecules. 

---