The Dunkerely method is used to estimate the lower natural frequency limit for a system of connected subsystems. It complements the Rayleigh method which gives an upper limit estimate. A Matlab script for performing this estimate is given in Dunkerley.zip More later…. – Tom Irvine
These Matlab scripts determine an optimum envelope for an acceleration power spectral density: envelope_plateau.zip The optimum envelope is the that which yields the lowest GRMS and Velocity RMS values. The acceleration is assumed to be the base excitation for an array of independent, parallel single-degree-of-freedom… Read more
Revised software uploaded on January 9, 2013 Accelerometers signals for pyrotechnic events often have spurious offsets. Numerous potential causes include: 1. Excitation of the accelerometer’s piezoelectric crystal natural frequency 2. Signal conditioner overload 3. Base strain sensitivity 4. Instrumentation noise 5. Electromagnetic interference These causes… Read more
These Matlab scripts calculate the natural frequencies and normal modes of a flat rectangular plate via the finite element method: rectangular_plate_fea.zip rectangular_plate_fea.m is the main script. The remaining scripts are supporting function. Rectangular elements are used for the numerical model, but the plotting elements are… Read more
Here is a set of Matlab GUI scripts for calculating the bending frequencies of both homogeneous and honeycomb-sandwich circular plates: circular_plate.zip * * * Here is a set of Matlab GUI scripts for calculating the bending frequencies of both homogeneous and honeycomb-sandwich annular plates: annular_plate.zip *… Read more
Here is a Matlab GUI script and reference paper for calculating the longitudinal natural frequencies of a beam or rod. beam_longitudinal.zip Long.pdf * * * See also: Beam Bending Frequencies – Tom Irvine
I am offering another Shock & Vibration course. The next course date is February 26-28, 2013 in Huntsville, Alabama. Location: Best Western Plus Madison – Huntsville Hotel 9035 Madison Blvd, Hwy 20 West, Madison, AL 35824 (Formerly The Inn at Madison) Students receive software &… Read more
These Matlab scripts calculate the natural frequencies of a beam via the finite element method: beam_base_accel_fea.zip They also have options for base excitation: 1. frequency response function 2. half-sine base input 3. arbitrary base input A ramp invariant digital recursive relationship is used for the… Read more
Here is a Matlab GUI script for calculating the bending fundamental frequency of a rectangular plate: rectangular_plate_bending.zip * * * See also: Beam Bending Frequencies Structural Dynamics – Classical Methods Page – Tom Irvine Connect with me on LinkedIn
Question from one of my readers If equipment is normally isolated in service, should HALT vibration testing be performed with or without isolators since the intent of this testing is to find operational and structural limits regardless of the real environment. Answer from Steve Brenner… Read more