Stability Analysis for Landing Gear Shimmy

Hello,

I am trying to generate stability maps on the k-v plane for a vibration analysis. I wrote the following command to find the roots. But I don't know how to extract the graph. Can you help me? I am attaching a chart as an example. Thanks.

Iz=0.5;
c=4;
Fz=7500;
e=0.037;
cfa=3.692;
cma=-0.116;
Kappa=-7;
a=0.041;
sigmaa=0.123;
for ind=1:6
    V=5*ind;
    b1=(V^2)*sigmaa;
    b2=(V^3)*Iz-Fz*cma*e*V*sigmaa+2*Kappa*V*sigmaa-sigmaa^2*c*V+Fz*cma*a*V*sigmaa-Fz*e*cfa*a*V*sigmaa+Fz*(e^2)*cfa*V*sigmaa;
    b3=(V^2)*(Iz*sigmaa*Fz*cma-Iz*e*Fz*cma+Kappa*Iz-Iz*sigmaa*Fz*e*cfa+Fz*cma*a*Iz-Fz*e*cfa*a*Iz+Fz*(e^2)*cfa*Iz)+Fz*cma*a*sigmaa*Kappa-Fz*e*cfa*a*sigmaa*Kappa+sigmaa*Kappa^2-c*Kappa*sigmaa^2-Fz*cma*e*sigmaa*Kappa+Fz*cfa*sigmaa*Kappa*e^2;
    kokler=roots([b1 b2 b3])
end

[Les Beckham]

What do you mean by "extract the graph"?

Where did the example chart come from? It has a lot more data on it than your code is generating. What do the x and y axes on your chart represent (in relation to the outputs of your code)?

Your code only generates six sets of two roots (see below).

In the future, please format your code as code like I did below. Press the left hand button in the CODE section before you type your code in (or paste it).

Iz = 0.5;
c = 4;
Fz = 7500;
e = 0.037;
cfa = 3.692;
cma = -0.116;
Kappa = -7;
a = 0.041;
sigmaa = 0.123;
for ind=1:6
    V = 5*ind;
    b1 = (V^2)*sigmaa;
    b2 = (V^3)*Iz-Fz*cma*e*V*sigmaa+2*Kappa*V*sigmaa-sigmaa^2*c*V+Fz*cma*a*V*sigmaa-Fz*e*cfa*a*V*sigmaa+Fz*(e^2)*cfa*V*sigmaa;
    b3 = (V^2)*(Iz*sigmaa*Fz*cma-Iz*e*Fz*cma+Kappa*Iz-Iz*sigmaa*Fz*e*cfa+Fz*cma*a*Iz-Fz*e*cfa*a*Iz+Fz*(e^2)*cfa*Iz)+Fz*cma*a*sigmaa*Kappa-Fz*e*cfa*a*sigmaa*Kappa+sigmaa*Kappa^2-c*Kappa*sigmaa^2-Fz*cma*e*sigmaa*Kappa+Fz*cfa*sigmaa*Kappa*e^2;
    kokler = roots([b1 b2 b3])
end

kokler = 2×1

-40.5991 24.6879

kokler = 2×1

-56.3019 17.8585

kokler = 2×1

-73.2406 13.7363

kokler = 2×1

-91.2275 11.0302

kokler = 2×1

-109.9002 9.1570

kokler = 2×1

-129.0162 7.8006

[burak akkaya]

I actually know very little about matlab. What I want to do is as attached. I tried a lot, but my knowledge was not enough.

[Les Beckham]

You did not answer any questions in my comment and, for some strange reason, you posted this, which should have been a response to my comment, as an answer to your own question. Thanks to Image Analyst for correcting that.

Matlab Answers is forum where generous volunteers answer specific questions for people that are having specific problems with aspects of Matlab programming. It is not a homework solving service.

If you really want to learn how to use Matlab, I suggest that you take a couple of hours to go through the free online tutorial: Matlab Onramp.

If you want further help with this specific issue, then answer the questions that I asked in my original comment (as a response to this comment, not as another answer that isn't actually an answer).