Amplitudes or seat to head transmissibilities calculation? i wrote a code based on some already optimized parameters to calculate amplitude ratios but curve is not matching can any one help me to find out where is the mistake

clc

clear all

%This is the programme with parameterssuggested by the somaye

m1=5.5 ;m2= 20;m3=4.17;m4= 9.337 ;m5=15.853 ;m6= 5.807;

k1=49340 ;k2=20000;k3=10000;k4=134400 ;k5=2916 ;k6=146640;k7= 68064;

c1=2475 ;c2=330 ;c3=200;c4= 250;c5=316;c6=3252.9;c7=1606.3;

M=[m1 0 0 0 0 0 ;0 m2 0 0 0 0; 0 0 m3 0 0 0;0 0 0 m4 0 0;0 0 0 0 m5 0;0 0 0 0 0 m6];

K=[k1+k2+k7 -k2 0 0 -k7 0; -k2 k2+k3 -k3 0 0 0; 0 -k3 k3+k4 -k4 0 0; 0 0 -k4 k4+k5 -k5 0;-k7 0 0 -k5 k5+k6+k7 -k6; 0 0 0 0 -k6 k6];

C=[c1+c2+c7 -c2 0 0 -c7 0; -c2 c2+c3 -c3 0 0 0; 0 -c3 c3+c4 -c4 0 0; 0 0 -c4 c4+c5 -c5 0;-c7 0 0 -c5 c5+c6+c7 -c6; 0 0 0 0 -c6 c6];

W = 2*pi*[0.5 0.63 0.8 1 1.25 1.6 2 2.5 3.15 4 5 6.3 8 10 12.5 16 20];% Experimental frequency range in radians

p=zeros(17,1);

x=zeros(17,1);

x1=zeros(17,1);

q=zeros(17,1);

y=zeros(17,1);

y1=zeros(17,1);

r=zeros(17,1);

z=zeros(17,1);

z1=zeros(17,1);

[rows columns] = size(W);

for i=1:columns % Retriveing number of frquencies

A= (-W(i)^2*M+j*W(i)*C+K);

B=[k1 c1; 0 0; 0 0; 0 0;0 0;0 0];

a = [1.01 1.01 1.01 1.02 1.03 1.06 1.08 1.1 1.16 1.29 1.45 1.23 1.01 0.96 0.86 0.71 0.63]; % Experimental results of seat to head transmissibility.

% b1= abs([0 0 0 0 0 1]*inv(A)*B*[1; j*W(i)]); % Analytical calculation of seat to head trasnmissibility.

%

% p(i)= abs(b1);

% x(i)= (p(i)- a(i)); % Difference between analytical and experimental STHT values.

% x1(i)= (x(i)^2); % square of the Errors.

end

[darova]

DO you have the picture of better resultion?

[veeresh g]

Answer 1

[darova]

These matrices look like symmetric except:

>> C-C'
ans =
     0     0     0     0     0     0
     0     0     0     0     0     0
     0     0     0     0   316     0
     0     0     0     0     0     0
     0     0  -316     0     0     0
     0     0     0     0     0     0
     
>> (K-K')/1000
ans =
         0         0         0         0         0         0
         0         0         0         0         0         0
         0         0         0         0    2.9160         0
         0         0         0         0         0         0
         0         0   -2.9160         0         0         0
         0         0         0         0         0         0         

Giving only 6th root?

b1= abs([0 0 0 0 0 1]*inv(A)*B*[1; j*W(i)]); % Analytical calculation of seat to head trasnmissibility. 

[veeresh g]

that is not actually sixth root it is the ratio of z6 to z0(input)

[darova]

Okay. But what about those matrices? Should they be symmetrical?

[darova]

This is how results look like if to multiply W by 3

W = 3*W;

[veeresh g]

yes mass, stiffness and dampming matrices are symmetric (sorry..i made a small mistake in C & K matrix formula modified now..but can you explain why the curve is not matching if i choose freqiency w instead of 3*w )

[darova]

but can you explain

Sorry, i can't. Just don't know

Maybe there is another mistake in stiffness or damping coefficients?

[veeresh g]

Those satiffness and dampling coeffients are optimized parameters using genetic algorithmas only. i guess those parameters are correct.. thanks for u r help

[veeresh g]

do u have any idea of optimization of parameters

[darova]

Maybe lsqcurvefit?

[veeresh g]

Thanks@ darova curves are matched if the frequency multiplied (radians we need to take) with 2*pi, i got to know this thing because of u r idea (w=3*w).. thanks a lot.

[darova]

Glad i helped. Why did you remove your code from question section?

[veeresh g]

haha..may its a problem for me in future..

[darova]

Please restore your question and code

[veeresh g]

sure...

[darova]

Thank you. It surely will help somebody

[darova]

Also, this part can be shorter

% p=zeros(17,1);
% x=zeros(17,1);
% x1=zeros(17,1);
% q=zeros(17,1);
% y=zeros(17,1);
% y1=zeros(17,1);
% r=zeros(17,1);
% z=zeros(17,1);
% z1=zeros(17,1);
[p,x,x1,q,y,y1,r,z,z1] = deal( zeros(17,1) );

% M = [m1 0 0 0 0 0 ;0 m2 0 0 0 0; 0 0 m3 0 0 0;0 0 0 m4 0 0;0 0 0 0 m5 0;0 0 0 0 0 m6];
M = diag( [m1 m2 m3 m4 m5 m6] );

[veeresh g]

thanq

[veeresh g]

do u have idea of optimization techniques.. iam trying to optimize some parameters with fire fly algorithm but unable to minimize the error..can u help me out how to choose parameters range

[darova]

WHich parameters you want to optimize?

Look here: LINK

[veeresh g]

hi..i found some solution thanqs for response..