The mean and variance dominate statistical measurements in both the time and frequency domains. They are also reflected by so-called amplitude domain measurements. The most basic of these is called a histogram. To measure a histogram, break a signal’s potential amplitude range into a contiguous series of N amplitude categories (i.e. x is between a and b) and associate a counter with each category.
Read MoreOne statistical description measured during a random shake test is the Control Spectrum. Specifically, this variable is often the output of an accelerometer mounted to the shaker table. The sensor’s voltage output is scaled to engineering units of acceleration, typically gravitational units (g’s) sampled at a fixed interval, Δt. This time-sampled history is transformed to the frequency domain using the Fast Fourier Transform (FFT). In this process, a series of “snapshots” from the continuous time waveform are taken and dealt with sequentially.
Read MoreVerifying the robustness of products (or their packaging) by subjecting them to shaker-induced vibration is an accepted method of “improving the breed”. While shock bumps and sine sweeps are intuitively obvious, random shakes with their jumps and hissing are anything but. Even the language of a random test is confusing at encounter. Let’s try to improve upon that first introduction to random signals!
Read MoreThe table top conference, put on by the Society of Maintenance and Reliability Professionals, was attended by about a dozen other maintenance and reliability companies whose specialties ranged from oil analysis to machine condition monitoring using handheld vibration data collectors. The exhibits attracted about 100 practitioners.
Read MoreThis patent protects an important contribution to CI’s Vibration Control System (VCS) business, its unique means of controlling the kurtosis of a random vibration signal. A conventional (Gaussian) random signal has a peak-to-rms ratio (the crest factor) of about 3. In contrast, a high kurtosis random signal of the same RMS intensity, with identical spectrum shape, can have a significantly higher crest factor.
Read MoreCrystal Instruments has enhanced Vibration Testing through interfacing their Spider Vibration Control product family with the very latest commercially available High Speed Cameras.
Read MoreJohn Morris Industrial (a Division of John Morris Scientific Pty Ltd), a growing force in the test and measurement / condition monitoring equipment supply market announced today that it has signed a distribution agreement with Crystal Instruments, covering Australia, New Zealand and Pacific Islands.
Read MoreThe short answer is, “a lot!” DSA (dynamic signal analyzer) users will immediately be able to do more of what they already do, faster and easier. VCS (vibration control system) users will discover new and safer ways of testing products to requirement specifications.
Read MoreStrain gages have long been the premier analytic tool for static stress/strain analysis, characterizing the basic strength of structures. But, they also have important roles to play in dynamic structural studies.
Read MoreEDM 5.0 (Engineering Data Management software), introduced approximately 8 months from the previous 4.2 release, includes both new features and enhancements to the existing software.
Read MoreSpeed reducers and other gearboxes are common industrial components. Monitoring their case vibration with accelerometers is an effective means of detecting problems within. To effectively diagnose these important mechanical elements, you need to understand the geometric details of their construction. Most importantly, you need to know the arrangement of shafts and the number of teeth on every gear within your transmission.
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