Automotive Multi-Sine Test

Multi-Sine is a new type of Sine test which facilitates multiple sine tones sweeping simultaneously at once. In automotive testing, engine mounted components such as fuel lines, turbos, headers, sensors, heatshield… are all subjected to high vibration levels during their operational life cycle. High cycle fatigue testing of engine mounted components is often done with a standard Swept Sine test. By performing a Swept Sine test, all resonances within the frequency ranges are excited and measured. Since the greatest fatigue damage happens at the excitation frequency and is also potentially high near these resonances, it is important to measure the vibration level at these frequencies. The standard Swept Sine only sweeps one frequency at a time with a single tracking filter. To test for fatigue, multiple sweeps need to be carried out for the entire frequency range at multiple times during a multiple sweeping rate.

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Remember when a Chief Scientist of CERN resigned from un-synchronized clocks?

In 2011, many of us read a startling news report of an experiment conducted by CERN  claiming that neutrinos appeared to be traveling faster than the speed of light.

The collaboration of the experiment, called OPERA (Oscillation Project with Emulsion-tracking Apparatus), made headlines with its claim that a beam of neutrinos made the 730-kilometre journey from CERN, Europe's particle-physics lab near Geneva in Switzerland, to the Gran Sasso National Laboratory near L'Aquila, Italy, faster than the speed of light by about 60 nanoseconds. The result defied Albert Einstein’s special theory of relativity, which states this cannot happen.

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High-Resolution Random Control at Low Frequencies (Multi-Resolution)

Random control is a fundamental vibration testing for various industries and manufacturers of products. The FFT based control algorithm transforms time signals to the frequency domain where analysis, calculation, comparison…average, (etc.) are done. The performance of Random control is determined by how well the FFT describes the system characteristics. Proper spectrum resolution must be chosen in order to avoid missing any desirable observations and to meet the requirement of the control performance.

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Modal Shaker Testing Using Periodic Random Excitation

Modal shaker testing is widely used for experimental modal analysis and to acquire frequency response functions. Either single or multiple modal shakers can be used. The type of excitation used may influence the quality of the testing result and frequency response functions. 

Although sinusoidal types of excitation signals are occasionally used for modal shaker testing, these tests are typically performed using broadband random type excitation signals. Among these common excitation types, Pure Random is widely used. The Hanning window is generally applied to alleviate leakage caused by the non-periodic signal.

Another popular excitation type is the Burst Random excitation signal. It gained so much popularity because no window function is required. The requirement is to have the burst length selected so that the response decays enough at the end of each time block data. With this constraint, there will not be any leakage in the measurement and a windowing function is not required.

Two somewhat arbitrary types of excitation signals are Pseudo Random and Periodic Random. The characteristics of these two signal types will be discussed in detail here. The results of using these excitation types will be compared to the more popular Pure Random and Burst Random types. It will be shown that the cost of additional testing time is well worth the superior estimation of MIMO FRF signals.

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Vibration Institute’s Annual Training Conference 2017 - Rochester, NY

The Vibration Institute’s Annual Training Conference is often referred to as offering ‘second to none’ education in vibration analytics and is considered the place to be for vibration and condition monitoring experts. As such, it has also become an excellent networking opportunity for industry elites, manufacturers, and incoming young professionals. With today’s ever accelerating changes in technology, beyond networking, it is also crucial to stay up to date on vibration analysis techniques with the most capable and usable equipment.

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Center of Operation and Monitoring of 12 or More Shaker Systems with API

Manufacturing plants often require controlled vibrations on various parts of the plant to run for several hours, days, or even weeks at a time. In some cases, continuous operation is required.

At these facilities, the affordable down time is limited to a few hours in a week. The continuous controlling and monitoring of independently running systems is another significant challenge.

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Mounting Strain Gage on UUT

Applying strain gages for measurement may sound daring, but it’s a lot simpler than it sounds. In this article, we will focus on key points of strain gage placement technique. It is important that the strain gage performs well and gives an accurate reading. This means the attachment point must be performed correctly to receive good results. As a result, the strain gage setup process requires a precise and correct following of directions. Crystal Instruments’ Spider-80SG is capable of calibrating and resetting measurement values prior to taking measurement. This is a standard step for all strain measurements to eliminate any offset before measurement starts.

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Post Process Data Acquired and GPS-stamped by the CoCo-80X

There are often instances where it may be beneficial to add location information to your acquired data. With the CoCo-80X, these GPS signals can be acquired simultaneously with other measurements -- there is no need to carry a separate GPS device. The CoCo-80X’s large LCD and touch-screen interface makes it easy to use the analyzer and acquire data. All measurements are combined into a single test file, so there’s no need to manage files.

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