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
Here is a Matlab GUI script which converts between various damping metrics: damping.zip The supported metric include: quality factor Q fraction of critical damping [zeta] loss factor [eta] 3 dB Bandwidth [delta omega] 3 dB Bandwidth [delta f] damping frequency [fd] decay constant [sigma] time… Read more
Here is a Matlab GUI script for calculating the natural frequency of a spring-mass system: sdof_fn.zip It can also be used to select total isolator stiffness for a given mass and intended natural frequency. It is version 1.1, so please let me know if there… Read more
Here is a Matlab script which calculates the H1 & H2 frequency response functions for a force and response time history pair. modal_frf.zip It is best suited for the case of random force excitation. It uses ensemble averaging. * * * Here is a Matlab… Read more
Question NASA-STD-7003A states wrt joint attenuation predictions that “….up to a maximum of three joints….” be used. I realize this maximum of 3-joint attenuation has been typically utilized in the industry. Does anyone know the basis behind this guideline (i.e. what’s the history and/or data… Read more
Two random signals of particular interest are white noise and pink noise. White noise is a random signal which has a constant power spectrum for a constant frequency bandwidth. It is thus analogous to white light, which is composed of a continuous spectrum of colours.… Read more
I have never formally published any of my papers in a refereed journal or even in an engineering magazine, but others who have done so have referenced my tutorial papers. I am enclosing samples, which include conference papers, etc. – Tom Irvine * * *… Read more
Consider a lightly damped, single-degree-of-freedom system subjected to broadband random base excitation. The system will tend to behave as a bandpass filter. The bandpass filter center frequency will occur at or near the system’s natural frequency. The system response will thus tend to be narrowband… Read more