Studying the modal properties of the structure under test is important to optimize the design of the test structure and to improve the NVH characteristics. Finite Element Analysis is widely used to obtain the mechanical properties of different objects. However, it is not only difficult to replicate the exact environmental constraints and boundary conditions but also challenging to obtain the damping ratios of the different modes. Experimental modal analysis not only helps in solving these issues but can also help in validating the results of the finite element model.

Hammer Impact Test Considerations

Roving excitation or response? Uni-ax or Tri-ax? SIMO or MIMO?

A modal impact hammer test is broadly classified between two types: roving hammer and roving response. Each method has its own pros and cons.

Updated "Scope of Business" statement by Crystal Instruments

This month, as part of a routine ISO 9001 audit process, we made a slight revision to Crystal Instruments’ “scope of business" statement. It now states:

The design, production, sales and servicing of hardware and software for machine vibration monitoring, dynamic measurement and environmental testing.

NewsJames Zhuge, Ph.D. - Chief Executive OfficerNovember 23, 2018Non-applications

Spider-80SG Interface with Rod End Load Cell

Measurements can be broadly classified into two categories: Static Measurements and Dynamic Measurements.

Dynamic measurements vary greatly over a short period of time (e.g., Vibration (Acceleration), Audio (Sound pressure), etc.). In these types of signals, we are mainly interested in the high frequency components so measurements down to DC are typically not necessary. For these measurements, we would use the AC input mode (or IEPE) which comes with a 0.375 Hz High Pass Filter. In most cases, the user sets another high pass filter to eliminate the low frequency components that are not needed. Crystal Instruments Spider-80X and Spider-80Xi systems are best suited for these types of applications.

Sandeep Mallela - Director of EngineeringNovember 21, 2018Structural Dynamics Testing

89th Shock and Vibration Symposium (SAVE) – Dallas, TX

Crystal Instruments and Sentek Dynamics attended the 89th Shock and Vibration Symposium in Dallas, Texas. The symposium, which is organized by Shock and Vibration Exchange (SAVE), is regarded as the leading forum for the structural dynamics and vibration community to present and discuss new developments and on-going research. The technical paper presentations and tutorials offered at the symposium revolve around applications such as shock-ship testing, earthquake engineering, structural dynamics, and shock and vibration instrumentation techniques; attracting attendees from all over North America.

NewsTrevor Ergas - Sales EngineerNovember 21, 2018Non-applications

Seatbelt Sensor with the Spider-80SG

As a heavily transportation reliant and automobile driving society, we have become dependent and quite trusting of the automotive industry for the seatbelt’s lifesaving properties. But, does one ever wonder how those seatbelt devices are certified for our utmost safety? Certainly, it is possible to monitor the speed and displacement as a safety check regarding how timely the seatbelt engages. There are few products on the market to ease the complexity of this testing and Crystal Instruments now offers one of such systems. The Spider-80SG integrates seamlessly with the IES 2098 Seatbelt Sensor. It is an accumulator and the accuracy of its readings depends on the voltage precision of the supply. The Spider-80SG provides this power and allows the counter to reset as needed.

Anastassia Tolpygo - Application EngineerNovember 21, 2018Environmental Testing

Advanced Engineering Show in Birmingham, UK (October 31 - November 1, 2018)

The Advanced Engineering Show was held in Birmingham, UK. The exhibition was located at the National Exhibition Center (NEC) in close proximity to the international airport. Various meeting points and discussion topics were dedicated to the aerospace industry, automotive industry, and more. The exhibition included many conferences highlighting the dynamic changes currently occurring within the fields of advanced engineering and manufacturing.

Jordi Gargallo - Europe Sales ManagerNovember 12, 2018Non-applications

NEW RELEASE: EDM Modal 7.2

EDM Modal 7.2 introduces a new type of modal testing called Multiple Input Multiple Output (MIMO) Stepped Sine. This technique has been implemented to allow users to control and monitor multiple channels according to an implemented control strategy.

The new release version of EDM 7.2 also has a new modal parameter estimation method called Poly-X which is Poly-reference Least Square Complex Frequency Domain (p-LSCF). This is a frequency domain-based curve-fitting method that is used to extract the modal parameters of the structure under test more efficiently.

Crystal InstrumentsNovember 12, 2018Structural Dynamics Testing

Crystal Instruments Sales Meeting 2018 - Milwaukee, WI

During the final week of September, Crystal Instruments hosted a National Sales Meeting for our North American distributors. We had 21 attendees consisting of partners from: Sage Technologies, The Wonderful Company, Midwest Measurement Products, APM, TMS, Instrumentation Resources Inc., MBA, Mimex, and Dalimar.

Trevor Ergas - Sales EngineerOctober 30, 2018Non-applications

Automotive Testing Expo 2018 in Novi, Michigan

Crystal Instruments and Sentek Dynamics attended the Automotive Testing Expo in Novi, Michigan. This event is regarded as the world’s largest vehicle, component, validation technology, and services exhibition. The show featured more than 400 exhibitors and over 9,000 attendees. It was an exciting dynamic to be a part of with many valuable interactions.

Reza Tavana - Sentek Dynamics Sales DirectorOctober 29, 2018Non-applications

ATS (Automotive Testing Show) in Istanbul, Turkey from October 16-17, 2018

The Automotive Testing show was held in beautiful Istanbul, Turkey from October 16-17, 2018. The exhibition was located close to the main automotive cluster in Turkey, where key players in automotive industry are located. The Expo offered attendees several presentations a day on the exhibit floor from leading companies in the automotive industry. Crystal Instruments was able to participate and presented their latest innovations in vibration testing solutions.

Jordi Gargallo - Europe Sales ManagerOctober 28, 2018Non-applications

Enhancement of Reading TEDS (Transducer Electronic Data Sheet)

Sensors with an embedded TEDS (Transducer Electronic Data Sheet) chip allows EDM software to acquire the sensitivities and other manufacturing details of the transducer. However, the software can be empowered to do much more.

Dual Shaker Vibration Control

Vibration testing is continuously evolving throughout time. The requirements of testing large and heavy devices demand shakers with larger sizes and higher force ratings. On the other hand, with the increase of size and force ratings comes the cost of lowering the usable frequency range of a shaker system. Shakers with 50,000 lbf force typically operates up to 2 kHz. Larger shakers can have usable frequency ranges of less than 1.5 kHz. The main reason for this frequency reduction in performance is that higher force requires larger armature, and this results in a lower first resonance frequency, thus reducing the useful shaker frequency range. Intuitively, the larger the shaker, the higher the price tag.

Jeff Zhao, Ph.D.September 27, 2018Environmental Testing

Noise Criteria (NC) Curves

Noise Criteria (NC) curves are primarily used to rate indoor noise levels. It is important that the background noise levels are within acceptable limits to ensure optimal speech communication for structures ranging from residences and offices to hospitals and schools.

Sandeep MallelaSeptember 27, 2018Acoustic Testing

Understanding the Stability Diagram

The Stability Diagram is an effective way to display and identify the modes of a structure under test. Nowadays, the Stability Diagram is the standard method for the modal parameter identification stage. It provides a graphical representation of the system's poles (modes) at different mode orders during the modal parameter identification stage.

Jeff Zhao, Ph.D.August 25, 2018Structural Dynamics Testing