Structural Dynamics Testing
Structural dynamics testing solutions include the high channel Spider-80X and the handheld CoCo-80X
Structural Dynamics Testing Applications
Structural Testing Capabilities
Roving Impact or Roving Response Hammer Testing
Random, Burst Random or Chirp Shaker Testing
Identify Resonance Frequency & Damping
Measure/Model Real or Complex Mode Shapes
Verify Linear Independence of Mode Shapes
Validate/Update Finite Element Models
Structural Testing Products
Many structural problems are solved by identifying the natural frequencies at which the structure resonates and the percent critical damping of each resonance. In some cases, operating vibration is reduced by changing an operating RPM or shifting a resonance frequency (by stiffening or mass-loading the structure) to avoid a frequency coincidence. Other problems are solved by applying a damping treatment to a structure that “rings like a bell”. Adding Isolation-mounts quiets floor vibration while appending a tuned vibration absorber can “split” a resonance to two acceptably different frequencies. All of these fixes are aided by applying a measured force to the problematic structure and measuring the ratio of its response acceleration to that force as a function of frequency.
The vibratory behavior and stress distribution of a vehicle or civil structure can be predicted mathematically using modern tools like a finite element model (FEM). FEM is a truly powerful preliminary design tool, but its findings must always be test verified in the laboratory. Once prototype or production hardware actually exists; laboratory or field tests can confirm (or invalidate) a FEM. One of the most basic yet informative comparisons is the similarity between the experimental and analytic modes of vibration of the structure. Each mode consists of a resonance frequency, a damping factor, a modal mass and a mode shape or deformation pattern. Modes represent an important form of structural data reduction, because any vibratory motion the structure can exhibit can be expressed as a linear combination of the mode shapes. Since vibration is only of interest over a limited frequency range, this allows describing the motion at thousands of locations and directions (degrees-of-freedom or DOF) using only a small number of modes. This greatly reduces the number of complicated dynamic equations need to describe the vibration and to predict the effects of a structural modification or to model the attachment of the tested structure as a component of a larger structural system.
Modal properties can be identified from a series of acceleration/force Frequency Response Functions (FRF). An electrodynamic shaker may be used to excite the structure with a force measured by a force gauge at one DOF. An accelerometer at the same or a second DOF measures the response motion. A set of FRFs with acceleration measured at each desired DOF and the force measured consistently at one of them completes the required data set. This set may be achieved with a single accelerometer that is roved around the structure while a sequence of FRFs is measured by a 2-channel DSA. More efficiently, multiple accelerometers can be applied to the structure, one at each DOF of interest and all of the FRFs measured simultaneously by a high channel-count DSA.
An alternative is to use a single accelerometer and substitute a force-instrumented impact hammer for the shaker, providing a compact kit for field use with a CoCo. While the data could be acquired by roving the accelerometer while impacting at a fixed DOF, most users prefer to exploit structural reciprocity; they mount the accelerometer at a fixed DOF and rove the impact DOF around the structure. EDM Modal provides the complete modal testing and analysis software which provides the modal parameters.
This updated PPT explains how GPS time stamping technology can help conduct dynamic signal measurements for both indoor and outdoor applications. Across CI products, CoCo-80x, GRS and Spider-80Xi all support accurate GPS timing.
Santa Clara, CA - November 25, 2025 — Crystal Instruments Corporation, a global leader in vibration testing, dynamic measurement, and data acquisition technologies, today announced that the United States Patent and Trademark Office has officially granted U.S. Patent No. 12,483,216 B2, titled “Data Recording Based on Dual ADC Architecture.” The patent is credited to inventor James Q. Zhuge, founder and CEO of Crystal Instruments.
The case described in this article examines the modal characteristics of a satellite model acquired from performing experimental modal analysis. A hammer impact test was carried out with two teardrop uni-axial accelerometers (mounted in different directions) to study the modal behavior. The roving excitation method assists in completely avoiding the potential mass loading side effect produced by a roving response procedure. A hard tip was selected to excite the higher frequency modes.
A violin was suspended on a frame to a imitate free-free boundary condition. Sentek Dynamics’ BT-100M shaker was used to excite a violin at the base of its front panel. Polytec’s PSV500 laser scanner was used to measure and acquire the data from the back panel of the violin. Crystal Instrument’s EDM Modal software processed and analyzed the dataset to provide the modal parameters of the violin.
Ground Vibration Testing (GVT) includes the modal analysis of an aircraft and its sub-assembly components to analyze and detect any changes to their structural properties.
Crystal Instruments CoCo-80X handheld dynamic signal analyzer allows users to acquire measurements with unparalleled convenience in the field. The rugged design features a compact display for quick, easy, and accurate data recording and analysis. This powerful hardware system is now combined with Crystal Instruments patented GPS time synchronization technology, featuring a time accuracy of 100 ns. Users can now execute Operational Modal Analysis to study the dynamic characteristics of large structures such as bridges and buildings.
The rugged and intuitive CoCo-80X handheld system is now combined with Crystal Instruments’ patented GPS time synchronization technology (featuring a time accuracy of 100 ns) to further expand field measurement capabilities. Users are now able to execute Operational Modal Analysis using the handheld CoCo-80X to study the dynamic characteristics of large structures such as bridges and buildings.
Our team is thrilled to announce the 11.1 version of Engineering Data Management (EDM) software. Packed with a range of new features and improvements, this update is designed to elevate the user experience.
Seminar attendees learned everything from the basics of setting up a modal test to best practices in testing and in-depth modal theory. Modal testing variations included hammer excitation, SIMO shaker excitation, and MIMO shaker excitation.
The Canadian Space Agency recently performed the Modal Analysis of a RADARSAT Satellite using five modal shakers. It is important to obtain the modal analysis of the unit-under-test because information about the natural frequencies, damping coefficients and mode shapes can be used to optimize its design and improve its structural behavior. The modal parameters about the mechanical properties of a structure help users understand its vibration characteristics during operating conditions.
The latest Experimental Modal Analysis Seminar was held from November 8-9, 2022 in Vancouver, British Columbia. Crystal Instruments partnered with Dalimar Instruments to present these modal training seminars in Canada. During the seminar, Dr. Peter Avitabile covered the basics of modal measurements, impact hammer tests, and shaker tests. The modal training seminar participants learned the theory behind techniques, performed measurements, and received hands-on training experience.
Dalimar Instruments and Crystal Instruments recently hosted an Experimental Modal Measurement and Analysis Seminar with Dr. Peter Avitabile from September 19th to September 20th in Montreal, Quebec. This joint seminar was held at Château Vaudreuil, an excellent facility with convenient amenities.
The rugged and portable CoCo hardware allows users to perform convenient measurement recordings and analysis in the field. Field operations are extended with the integration of EDM Modal software to provide a seamless modal analysis procedure.
Frequency Response Function (FRF) is widely used in structural testing. Accelerometers are typically used and the acceleration vs. excitation force is measured as FRFs.
Written in collaboration between PCB Piezotronics, Inc., Crystal Instruments, and Team Icewave
Icewave has an overall record of seven wins and six losses. Marc DeVidts, Icewave creator and team lead, believes some of the losses may have been due to the blade not impacting opponents effectively. Because of the power behind Icewave, some of these losses can be attributed to self-inflicted damage from its own rotating horizontal blade. The modal testing will be used to help increase striking effectiveness.
The experimental object in this modal test is a hood cross-flow fan with an overall structure that includes a roulette wheel, rotor frame and cross-flow blades that are composed of metal materials. The fan is hung using bungee cords to imitate free-free boundary conditions.
This article examines the acquisition of modal characteristics from a train wheel through experimental modal analysis. Train wheel and rail interactions are critical components worth studying. If the wheel-rail interactions while accelerating or braking excite any of the system modes during the ride operation, it can induce an undesirable effect upon the passengers’ ride and comfort. Hence, the execution of modal analysis is vitally important.
Modal testing provides a crucial verification link in structural design by verifying the accuracy of simulation results and determining the structural characteristics of the actual product.
Crystal Instruments is excited to announce the release of EDM 10.0, the latest software version for all Spider and CoCo products serving advanced and fundamental industries in addition to furthering academic advancements.
The Modal Data Acquisition (MDA) function for the CoCo-80X/90 allows users to conveniently acquire modal data in the field. The CoCo Testing Plan provides an overview of the measurement process and also provides the ability to customize the measurement entries.
This article describes a step-by-step process of the CoCo MDA function along with the CoCo Testing Plan feature. A brief overview of transferring the data from the CoCo to EDM Modal in order to post-process the data is also presented.
This article examines the acquisition of modal characteristics from a bullet train wheel by performing experimental modal analysis. The wheel vibrations affect the dynamics of the wheel-rail interactions. Understanding these vibration characteristics will help mitigate the vibration and noise at high speeds.
Oregon State University in Corvallis, OR recently purchased a 64-channel Spider-80SGi data acquisition system. Dr. Armin W. Stuedlein, professor of geotechnical engineering said the Spider DAQ will be used for studies on in-situ liquefaction and cyclic softening studies, performance of ground improvements, and testing of full-scale foundations.
Executing the modal analysis of a structure is crucial in order to analyze the modal parameters of a test object. The natural frequencies, damping and mode shapes of the unit under test provides help to adjust the mechanical properties of a structure by optimizing the design and improving the structural behavior of the test unit. Consequently, modal analysis is a critical part of product development.
Structural measurements on infrastructure are growing in demand given the aging buildings, bridges, and dams that populate countries around the world. Structural measurements are not the only measurements needed for aging infrastructure, but they do play a role. In the structural measurement category, Crystal Instruments offers products to measure and analyze data for large structure measurements like the measurements done on the Vieux Emosson Gravity Dam.
In any multi-channel DAQ or vibration control system, where each channel is capable of measuring unique sensors, it is necessary to quantify how the channels are different from each other. The channels are designed identically, but component tolerances will cause differences between channels.
Founded in 1996, Crystal Instruments designs and manufactures instrumentation products for machine vibration monitoring, dynamic measurement, and environmental testing. The products are developed in Silicon Valley and our modern lab in North Carolina. Crystal Instruments products are thoroughly tested on a variety of vibration shakers and environmental chambers in our lab during the design phase to meet the extreme requirements of military and aerospace applications.
Watch Aakash Umesh Mange’s new video featuring the powerful Spider-80SG data acquisition system combined with the versatile EDM DSA software. This simple and efficient package for strain gage measurements can include the Spider-80Xi chassis, which scales up to 512 channels. Contact our team to schedule a demo or to learn more.
Watch Darren Fraser’s Multi-resolution Overview presentation from this year’s ESTECH 2021 conference. Viewers will receive a brief review followed by several practical application examples. The Multi-Resolution function is patented by Crystal Instruments.
EDM Modal software provides the Playback Analysis feature which allows users to import recorded time signals and process measurement data to obtain the related spectrum signals. This feature allows users to carry out all the field measurements in one attempt before post-processing and analyzing the measured data in detail on a lab PC.
Modal testing involves collecting frequency response functions using either an impact or shaker excitation technique. Impact testing is often performed due to the ease of the test setup and simplicity of the measurement process. But larger structures may not be adequately excited with single impact excitation locations as the test progresses.
The EDM 12.1 release introduces Live Frequency-Domain Animation to help users visualize and interpret structural vibration data during testing. With this enhancement, users can now observe Operational Deflection Shapes (ODS) in real time while running Random, Sine, or other data acquisition or modal tests.
Modal analysis of a cantilevered plate was successfully performed using the Luma-600 laser vibrometer. The results align with expectations and confirm the effectiveness of the Luma-600 as a non-contact vibration measurement tool for accurate and efficient modal testing.
There are two steps for converting an analog signal into a digital signal – quantization in time (sampling) and quantization of amplitude. Any signal that goes through the sampling process is subject to the effect of aliasing. The common use of the word ‘alias’ is used to describe a false name or identity, which is similar to how the term is used in signal processing.