I will be presenting a 3-hour tutorial session at the 83rd Shock and Vibration Symposium in New Orleans, on November 4, 2012. My session is called “Shock Response Spectra & Time History Synthesis.” Students will receive basic instruction in calculating shock response spectra for time… Read more
Matlab is a great programming language and environment because of its ease of use, great visualization, and rapid prototyping abilities. Matlab has a feature called MEX, Matlab Executables. See: Matlab MEX Introduction MEX files allow Matlab scripts to call user-supplied functions written in C/C++ and… Read more
A rocket vehicle behaves as a free-free beam during flight. The vehicle’s body bending modes can be excited by wind gusts, aerodynamic buffeting, thrust offset, maneuvers, etc. Note that the mass and stiffness properties vary along the vehicle’s length. Furthermore, the mass properties change with… Read more
This script demonstrates a Matlab anonymous function with variable coefficients. It also performs integration using the quad function, which uses adaptive Simpson quadrature. This example is from an actual engineering problem for beam vibration. L=27.5; beta=4.73004/L; % sigma1=( sinh(beta*L) +sin(beta*L))/(cosh(beta*L) -cos(beta*L)); % core=@(x) ((cosh(beta*x)-cos(beta*x))-sigma1*(sinh(beta*x) -sin(beta*x))).^2;… Read more
The most widely used algorithm for the Shock Response Spectrum (SRS) calculation for base excitation is the ramp invariant digital recursive filtering relationship given in: David O. Smallwood, An Improved Recursive Formula for Calculating Shock Response Spectra, Shock and Vibration Bulletin, No. 51, May 1981.… Read more
Modal Transient Analysis of a System Subjected to an Applied Force via a Ramp Invariant Digital Recursive Filtering Relationship: force_ramp_invariant.pdf Reference Papers: Smallwood Irvine General Coordinate Irvine Impulse Response Function 1 Irvine Impulse Response Function 2 Irvine SRS * * * * * * * * * *… Read more
I have posted the January 2012 Newsletter at: http://www.vibrationdata.com/newsletters.htm The topics are: Slow Earthquakes Rumbler Siren Shepard Tones Toadfish Mating Call There are seven accompanying sound files and one Matlab script. Please let me know if you have any questions. Thank you, Tom Irvine
I am evaluating plotting programs for Ubuntu. I already have plotting capability via Matlab and Python/matplotlib running under Ubuntu. The Matlab export plot quality is ok but not great. So far my Python knowledge only extends to making static plots. Identifying interactive, dynamic plotting methods… Read more
Scilab is an open source, cross-platform numerical computational package and a high-level, numerically oriented programming language. It can be used for signal processing, statistical analysis, image enhancement, fluid dynamics simulations, numerical optimization, and modeling and simulation of explicit and implicit dynamical systems. Scilab is an… Read more
Sage Notebook is a free web-based, open-source, mathematical worksheet development environment. It is an alternative to Magma, Maple, Mathematica, and MATLAB. It can perform symbolic algebraic and calculus operations. * * * Here is an example of an algebraic computation in Sage…. Partial fraction decomposition… Read more