8001 Impedance Head, tapped 10-32 UNF platform

Impedance heads offer a simple approach to the measurement of point mechanical mobilities and impedances. They can be used on a wide range of structures, including rotor blades, polymers, rubbers, the human body, artificial mastoids, fruit, welds, wood and metal panels.

Product Data

Uses

Point measurements of mechanical mobility and impedance of light structures
Point measurement of damping, loss factors and natural frequencies at points on light structures and materials
Calibration of the Brüel & Kjær Artificial Mastoid Type 4930 (Type 8000 only)
Biological measurements (Type 8000 only)

Features

Piezoelectric accelerometer and force gauge sharing the same housing and mounting point
Individual calibration charts
High sensitivity accelerometer
Operating frequency range up to 10 k Hz
Operating temperature range up to 260° C (500° F)

* The accelerometer in the impedance head produces an acceleration-related output, which does not give the mobility or impedance function directly. Instead, force and acceleration signals give the so-called dynamic mass and its reciprocal, accelerance. If mobility and impedance measurements are required, the acceleration signal must be integrated by the preamplifier. Alternatively, if a dual channel analyzer is used, the mobility or impedance function can be derived via post-processing in the analyzer.

The two impedance heads are identical in construction apart from the method of attaching each to the structure. The Type 8001 has a tapped 10 – 32 UNF hole in the base for attaching it to a surface using a stud. The Type 8000 has an untapped base consisting of a finely finished beryllium disc. Both contain the same piezoelectric accelerometer and force gauge in a sealed titanium housing. The accelerometer is a high-sensitivity compression type offering stable and accurate performance over its long working life. The force gauge is also of the highest quality. The outputs of the transducers are fed to individual sockets on the side of each impedance head. Each impedance head comes with an individual calibration chart (see Fig. 1).

The accelerometer is located above the force gauge. A critical part of the design lies between the force gauge and the base of the impedance head. The force gauge is mounted as close as possible to the driving point, and the stiffness between the two is made extremely high. Thus, the force gauge gives a true indication of the forces transmitted to the point on the structure. The high stiffness of the materials used in the construction ensures that the phase difference between the force and acceleration output signals is less than 1° over a frequency range of 10 kHz.

Impedance Head Type 8000

Impedance Head Type 8001

Measurements on light structures

Measurements on heavy...

For a full Description and Specifications, see Product Data