Crosses of the World
Matthew 10:38 And he that taketh not his cross, and followeth after me, is not worthy of me. * * * Luke 9:23 And he said to them all, If any man will come after me, let him deny himself, and take up his cross… Read more
Extending Steinberg’s Fatigue Method
Here is a paper for… Extending Steinberg’s Fatigue Analysis of Electronics Equipment Methodology to a Full Relative Displacement vs. Cycles Curve electronic_rd_n.pdf extending_Steinberg.pptx This paper also shows in a very roundabout way that “fatigue damage equivalence” between sine and random vibration occurs when the sine… Read more
FFT for Machine and Pump Diagnostics & Acceptance Evaluation
This Matlab script calculates the one-sided, full amplitude FFT of an acceleration time history: FFT_VD.zip It gives the output FFTs in acceleration, velocity and displacement formats. It is useful for evaluating machine and pump vibration where there are distinct sine tones and harmonics. The main… Read more
Half-Power Bandwidth Method
Please see the following update: MDOF Frequency Response Function Natural Frequency & Damping Extraction including Modal Overlap. Post Link The half-power bandwidth method can be used to estimate the damping ratio and corresponding Q value from the frequency response function of a structure which has… Read more
Data Curve-Fitting
Here is a good website for curve-fitting: zunzun From the website… Here you can curve fit and surface fit your 2D and 3D data online with a rich set of error histograms, error plots, curve plots, surface plots, contour plots, VRML, auto-generated source code, and… Read more
The Veil of the Temple was Rent in Twain
Both the Tabernacle and the Temple in Jerusalem had an inner room called the “Holy of Holies” which had a thick curtain or veil that separated it from the outer room. This inner room was God’s special dwelling place in the midst of his people.… Read more
Miner’s Cumulative Fatigue via Rainflow Cycle Counting
This blog entry is a work-in-progress. Fatigue analysis can be performed in the time domain using rainflow cycle counting. This is an elegant, brute-force approach. One advantage of the time domain approach is that it tends to highlight the occurrences of peaks above 3-sigma for… Read more
Response of a Single-degree-of-freedom System to Base Excitation
These Matlab scripts calculate the response of a single-degree-of-freedom system to base excitation: sdof_base.zip sdof_base.m is the main script. The remaining scripts are supporting functions. The base excitation may be a half-sine pulse, terminal sawtooth pulse, arbitrary pulse, or a PSD. * * * See… Read more
Response of a Two-degree-of-freedom System to Base Excitation
Functions for calculating the response of a two-degree-of-freedom system to base excitation are given in the Vibrationdata analysis package posted at: Matlab script: Vibrationdata Signal Analysis Package * * * See also: Two-degree-of-freedom Systems * * * – Tom Irvine
Two-degree-of-freedom System, Natural Frequencies
Here is a set of scripts that calculate the natural frequencies and mode shapes for a two-degree-of-freedom system. The scripts are posted at: two_dof_system.zip The main script is: two_dof_system.m The remaining scripts are supporting functions. * * * See also: Two-degree-of-freedom Systems – Tom Irvine