Inner and Outer radii of cylinder if Area and Iz are known

Hello all,

I have several pipe sections of which I know the:

1. Moment of Inertia Iz = pi*(d_out^4-d_in^4)/64

2. Area A = pi*(d_out^2-d_in^2)/4

Can anybody think of a way to find the d_out and d_in ?

Thanks

Answer 1

[Star Strider]

Yes!

This works:

% MAPPING: d(1) = d_out,  d(2) = d_in
pipe = @(d,Iz,A) [pi*(d(1)^4-d(2)^4)/64 - Iz;  pi*(d(1)^2-d(2)^2)/4 - A];

Iz = 100;                               % Create Data
A  =  25;                               % Create Data

D = fsolve(@(d) pipe(d,Iz,A), [1; 1]);

You need the Optimization Toolbox to use the fsolve function.