Crystal Instruments Corporation

Sentek Dynamics Inc.

Weijie Zhao

James Q Zhuge

Aakash Umesh Mange

Hongjian Gao

Michael Nichols

Yihao Liu

Sensors outside of a control loop are used in a single axis electrodynamic shaker where an armature exerts variable amounts of vibration with a single degree of freedom on a test unit affixed to a support table. The sensors are remote from the test unit, such as laser sensors measuring movement of the test unit. Typically an array of such shakers move a support table having an affixed test unit. A controller uses inputs from the remote sensors to signal warnings of overturning moments of the support table that can damage the armatures or to shut down.

Safety apparatus for one degree of freedom electrodynamic shaker

A vibration testing system for structures visually displays vibration analysis information in the form of a graphic animation using a 3D model of the object. While only a subset of the surface points of the object model correspond to sensors on the structure, an interpolation feature of the system allows deformation information for all points of the model to be estimated. Interpolation weights can be calculated in advance to allow for real-time display of a test. Color can be used to enhance visualization of vibration amplitudes. The visualization can be performed offline after a vibration test has been completed to show modal analysis results or can be done in real-time using either blocks or RMS data obtained while the vibration testing is still on-going. This is especially useful for adjusting test parameters, such as the excitation location, amplitude or both, for more effective testing.

Vibration visualization with real-time and interpolation features

A modal vibration analysis system and corresponding method is provided. Exciters are coupled to a structure under test for generating vibrations in the structure. Sensors are coupled to the structure at multiple locations for sensing vibrations generated in response to the excitations. A controller provides drive signals to the exciters such that the sensor signals have a target output spectrum with specified characteristics in multiple designated frequency domains of the spectrum, characterized by a random phase for each frequency. Modal analysis processes digitized sensor signals with a Fast Fourier Transform conducted at two or more specified data sampling rates to synthesize a spectrum containing data points with finer frequency resolution for lower frequency range, and regular frequency resolution for higher frequency range. From the multi-resolution spectra, natural frequencies and damping coefficients are determined at each mode, and a mode shape at each natural frequency is computed.

Modal vibration analysis system

A shaker test apparatus is provided along with a method of collecting and processing images, wherein a shaker table is driving the device under test by a vibration controller at a known vibration frequency and period, wherein a device under test obtains a steady-state vibration characteristic of that excitation frequency when mounted on the shaker table. While the device under test is being excited, a trigger signal controller triggers a camera to capture a series of still image frames at a regular sampling frequency that is less than the vibration frequency (under-sampling), and a timer associated with the camera records a timestamp of an image capture time for each image frame. A computer processor uses the timestamps to remap the order of the image frames, shifting each frame's capture time backwards by a specified multiple of vibration periods in order to correctly represent a single vibration period beginning with an earliest captured image.

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Los Gatos, CA, United States of America

Weijie Zhao