Here's the guts of it everything else is just eye candy
%build some matrices
K=[k1+k2 -k2;-k2 k2];
M=[m1 0;0 m2];
M_baseline=[m1 0;0 0]; %baseline case, ie main mass only
C=[c1+c2 -c2;-c2 c2];
F=[1;0];%excite the main mass, ie engine case
%runs happier
x1=zeros(1000,1);
x2=zeros(1000,1)...
Your calculator has an error in it. If you set m2 to a very small value the TL should be the same as the 1dof system. Where is the force being applied, ie do you have a subframe (m2 is excited) or a conventional harmonic damper (M1 is excited)?
Ah, yes I thought the thickness was a bit exotic. Sorry, i literally have no idea how to spec an electromagnet for that job. It rather depends on what you need it to do.
1689 rpm is 28.15 Hz. You may have some 2nd order at twice that
Something doesn't add up, you'd expect to see at least some content at tooth mesh frequency.
et voila, probably got mistakes, haven't done this for years, no hanning or corrections
%spectrum271828
%Greg Locock
%29 Dec 2025
%v .1
%To do
%Dependencies
%none
%Changelog
clc;
clear;
close all
%make a time signal
t = 0:.125:10;
x = sin(2.1*pi*2*t) + 2*sin(2*pi*2.35*t);
%plot it and...
That means the energy in each bin is NOT a PSD, you can just add the squares up, and square root the sum. This of course will make your peak higher, but the energy of the total signal stays the same.
That all depends on what units your spectrum is in. Depending on the method used to analyse it some options are g, g^2, g/sqrt(Hz) or g^2/Hz. The correct generic approach is to turn it into energy per bin (frequency line), sum the bins, and then convert back into the desired units. This is...
I can help once the rail starts vibrating, but the excitation mechanism is new to me. This paper seems relevant but I can't download it
Control of wheel/rail noise and vibration
NTL Rosa-P (.gov)
https://rosap.ntl.bts.gov
PDF
by PJ Remington · 1982
1 yes acoustic intensity measurements. Also experimental modal analysis.
2 your big problem will be identifying the forcing functions
3 there are industry standard methods for measuring noise. I suggest you find out what your industry uses.
After a bit more thought I realised that in many cases we are more interested in the force that is going into the 'foundation' via k1 and c1, rather than the vibration of the mass m1 itself. Also I wondered whether a TMD could be used on a typical engine mounted on rubber engine mounts. A rule...
Oh, and here is the last one but with the TMD tuned to 7 Hz
So you get less attenuation, but over a bigger frequency range.
Units used throughout are any self consistent set, so N/m, N/m/s and kg in SI
Just a quick look at TMDs, which came up elsewhere. In this case I am looking at the normal automotive case, where a large body is excited directly by a force, and we then bolt on a TMD. Typical example is the harmonic damper on the crankshaft, used to suppress torsional vibrations, and bending...
As i said we do an rpm sweep, which makes it obvious if it is resonance or a forced response.
You can measure TVs with a TV analyser (surprise) - a toothed wheel on the nose of the crank, a pickup, and an FM demodulator, which turns your pulse train into a usable signal. An F to V box would...
Welcome to the world of experimental modal analysis! Simplest way with what you have already is to mount two accelerometers. Move one around and plot the ratio of the amplitude at 87 Hz to the reference fixed accelerometer. Hopefully you'll get a ) shape along the length of the unit. That isn't...
You get 2 answers because I can't find out if it is a 2 stroke or a 4 stroke!
4stroke
Nope, firing frequency for a V16 4 stroke at 1500 rpm is 200 hz, which doesn't solve your problem admittedly.
So you've got 3.5 order. Wow, that is odd. Also odd is the absence of ANY firing order vibration...
