James Instruments, Inc. Emodumeter MK II
For the Determination of the Resonant Frequency of Materials
The principal used in the Emodumeter is based upon the determination of the fundamental resonant frequency of vibration of a specimen generated by an impact and sensed by an accelerometer. The frequency spectrum is computed and displayed by the meter.
System:
The Emodumeter MK II has an automatic feature that computes the maximum amplitude, which eliminates cumbersome frequency scanning. Frequencies are automatically shown in the display and a cursor allows the user to move along the frequency spectrum. Also the time domain signal and the frequency spectrum can be stored and uploaded to a PC for further analysis and inclusion in reports.
Resonance Frequency:
The Emodumeter MK II performs a Fast Fourier Transform that allows the indentification of the resonance frequency in the Frequency Spectrum.
Durability of Concrete:
The determination of flexural resonance is very important when studying the degradation of concrete under accelerated freezing and thawing cycles and aggressive environments on concrete specimens.
The advantages of resonance methods are:
For the determination of the resonant frequency of materials, the Emodumeter measures the resonant frequencies of the three different modes of vibration Longitudinal, Transverse (Flexural) and Torsional.
From these the following material characteristics can be calculated: Young's Modulus of Elasticity, Modulus of Rigidity and Poisson Ratio.
Frequency range: | from 10 Hz to 40 kHz |
Sampling frequency: | 10, 20, 40 or 80 kHz |
Frequency resolution: | from 4.9 to 78.1 Hz |
Record length | 1024 or 2048 points |
Output bias level: | 9.2 V |
Accelerometer sensitivity: | 9.60 mV/g (0.979 mV/m/s2) |
Battery: | 12 Volt. 4-10 hours - continuous use |
Display: | 320 by 240; backlit for daylight use |
Storage: | 200 plus readings |
Software: | Windows compatible 9x/me 32MB Ram |
Impactors: | Set of 6 hardened steel balls |
Operating Temperature Range: | 0°C to 40°C |