Calibration Dynamics Ltd. - PRODUCT NEWS




Modal Analysis

Modal Analysis is used to determine the frequency at which vibration naturally occurs within a physical system, and the modal shapes it assumes within its vibration.

This analysis is a critical component of the design of a vibration model. Structural elements such as complex steel floor systems can be particularly prone to perceptible vibration irritating building occupants and can also damage sensitive equipment. This will shorten equipment life and can cause premature or complete failure. Fatigue analysis can also be used to determine the potential for failure/ damage resulting from rapid stress cycles of vibration.

Detailed modal analysis determines the fundamental vibration mode shapes and corresponding frequencies. This can be relatively simple for basic components of a simple system, or extremely complicated when qualifying a complex mechanical device or a complicated structure.

Calibration Dynamics offer a broad range of shakers and excitation systems. Standard shakers are available in a variety of sizes offering frequency ranges from DC to 10 kHz bandwidth and force ranges up to 1115 N (peak). A comprehensive and almost exhaustible series of mounting arrangements can be produced, allowing the mounting of each shaker, allowing the mounting of each shaker in almost any position to facilitate accurate testing in the most arduous applications.

Designed by a team of world respected modal testers including University of Cincinnati professors, the Modal 50A was developed to be highly portable, easy to set up and simple to use. It is these design features that makes the Modal 50A a number one selling exciter.

The Modal 50A (and multiples thereof) is ideal for exciting structures smaller than a full size car. A centre bore extending through the armature, housing, trunnion base, and inertial masses allows a stinger to be easily positioned along its axis. It may then be placed as close to the test article as desired and the chuck tightened down to grip the stinger firmly. The stinger need not be cut off, thus retaining flexibility for future use in different orientations and applications. An oscillatory force of 50 pounds keeps the tension in the stinger while delivering peak dynamic force. This virtually eliminates measurement errors due to bending moments and side loads that can result when using compression loading of traditional stingers.

It has a 1" stroke, sufficient for flexible structures and low frequency "suspended shaker" tests and a 50 ponds dynamic force - enough for larger test articles. Its lightweight armature (<0.4lb) enables the testing of small items and also minimises mass loading, dramatically reduces force drop-off at resonances of the test specimen. And its broad frequency range (1 - 4000 Hz) handles almost every modal survey. The Modal 50A is also suitable for multi-shaker random, single point random, multi-point sine dwell and even burst random.

The Modal 110 delivers 500N of force and a 1.5" stroke peak-peak. This gives it twice the force and 50% more stroke than the Modal 50A.

The "big brother" to both of these though is the Modal 250A. It delivers a massive 1115N force with a stroke length of 2 inches peak to peak. This means that it is capable of performing total vehicle modal tests on anything larger than your average car, ie a truck, jet, even a space shuttle!

The smallest member of the MB Dynamics Shaker family is the Modal 2. It is MB's smallest exciter to date. It delivers a 2lb force (9N) and a 0.16" (4mm) stroke peak -peak.

With a height of just over 4" and a 3.5" square base the Modal 2 is very small which makes it ideal for testing in compact areas. The armature through hole furthers the versatility by allowing easy adjustment of the 10-32 threaded stinger. MB Dynamic's promise to provide the most accurate test systems is evident in the moving element which weighs in at 0.6oz. The AC coupled US-20W amplifier gives the Modal 2 a broad usable frequency range of 10Hz to 10kHz. And the analogue meter on the frontface makes monitoring the 1 amp maximum output current straight forward.

This versatile product range is already extensively used throughout aerospace, automotive and structural monitoring environments. At Calibration Dynamics we can provide individual solutions from simple shakers to bespoke shaker and amplifier systems for individual applications.
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For more information, please contact :-

Calibration Dynamics Ltd.
7 Regents Court, South Way, Walworth Industrial Estate,
Andover Hampshire SP10 5NX United Kingdom
Phone: +44(0) 1264 339 030
Fax: +44(0) 1264 339 040
Email:
sales@calibrationdynamics.com
Web:
www.calibrationdynamics.com

May 2007

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