Matlab Utilities
Here is a script for reading ASCII text files into Matlab: read_data.m This script uses uigetfile to open a dialog box for selecting the input file. – Tom Irvine
Convert Time History to Nastran format
Here is a Matlab script that converts a time history to a format which can be input to Femap or some other preprocesser for Nastran analysis. time_history_nastran.m with supporting function: datafix.m It can be used for force, pressure, acceleration or other amplitude types. The script… Read more
Webinar Unit 1 – Natural Frequencies
We held our first Shock & Vibration Webinar on January 17, 2014. This presentation was sponsored by the NASA Engineering and Safety Center, to which I express gratitude. A link to the audio/visual recording will be posted here in the near future. In addition, here… Read more
Rice Characteristic Frequency
The Rice characteristic frequency f of a time history is where y is the amplitude It is useful for estimating the dominant frequency for signal which is fairly sinusoidal. Here is a Matlab script: rice_frequency.m See also: Vibrationdata Signal Analysis Package – Tom Irvine
Some Music Acoustics
Here is a chart showing the natural frequencies of piano keys: piano.pdf Here is a paper on some basic music theory: music.pdf * * * See also: Fun with Sound Files Wind Chime Acoustics Tuning Fork Sound and Vibration: tuning.pdf * * * – Tom… Read more
Beam Bending, Finite Element Analysis
Here is a paper which gives a derivation of the mass and stiffness matrices for beam bending: beam_FEM.pdf * * * Here is a Matlab script for the modal analysis of a straight beam. beam.zip * * * Here is Matlab script for the modal… Read more
FRF Substructuring
This post is a work-in-progress… Frequency Response Function based substructuring (FBS) predicts the dynamic behavior of a coupled system on the basis of free interface FRFs of the uncoupled components. Here is a tutorial paper: Frequency Response Function Substructuring Modal damping requires special consideration: Notes on… Read more
Free Holy Bible, Hardcopy
The Bible is the written word of God. The Old Testament begins with the stories of the Creation, Adam and Eve, and the Patriarchs. It continues with the law and commandments that Jehovah gave to the Moses and the Children of Israel. The New Testment… Read more
Trust in the Lord
5) But I have trusted in thy mercy; my heart shall rejoice in thy salvation. 6) I will sing unto the LORD, because he hath dealt bountifully with me. Psalm 13 * * * Trust in the LORD with all thine heart; and lean not… Read more
Spiritual Altars to God
The patriarchs, prophets and kings of the Old Testament constructed altars unto the Lord. Early altars were built from unhewn stone. The altars were used for burnt sacrifices and offerings. They were also used for prayer, worship, covenants and as memorials unto the Lord. *… Read more