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function du=mydiff(tau,u) tau= 1:20; for tau=1:20 u(tau)=1; end b=4.5; %backlash,2b=9 micro metre Z1=62; %no. of teeth in Gear Z2=42; %no. of teeth in Pinion T1=7640; %torque of Gear in N-mm N1=5000; %Speed of Gear in rpm M1=11.815; % mass of gear in kg M2=5.357; %mass of pinion in kg I1=37257; %inertia of Gear in kg-mm2 I2=82103; %inertia of pinion in kg-mm2 me=2.279; %mass equivalent in kg km=2.3426e7; %average stiffness in N/m Fm=105; %total Normal force in N omega0=sqrt(km/me); % frequency of gear pairin rad/sec omegae=(2*pi*Z1*N1)/60; %natural frequency in rad/sec ohm=omegae/omega0; % frequency ratio F0=0.4482; %Dimensionless load=(Fm/me*l*omega0^2) zeta=0.06; %damping ratio t=; %f(u(tau)) Dimensionless nonlinear gap function tau=omega0*t; %Dimensionless time l=1e-6; %characteristic length q(t)=l*u(tau); thetaj=0; kj=[23.5396 3.5448 0.8489 0.5454 .0302 0.5012]*10^6; kbn=kj/km; ej=[20 3.45 0.26 .45]*10^-6; ejb=ej/l; for tau=1:20 if(u(tau)>b/l) f(u(tau))=u(tau)-b/l; end if(u(tau)> -b/l && u(tau)<b/l) f(u(tau))=0; end if(u(tau)<-b/l) f(u(tau))=u(tau)+b/l; end end for n= 1 :5 sum1=kbn*cos(n*ohm*tau)*f(u(tau)); end sum1=sum1+1; for j=1:5 sum2=ejb*j*j*cos((j*ohm*tau)+thetaj); end
du(1) = u(2); du(2) = F0+(ohm*ohm*sum2)-sum1-(2*zeta*u(2)); du = [du(1); du(2)];
[tau,u] = ode15s('mydiff', [0 25], [1 1]); plot(tau,u(:,1))
whats wrong with this program?
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3. There are no comments after the initialization comments. No comments about what the loops and ode15s are supposed to do.
4. No initialization of du early in the function so that an error in the program will throw an additional, secondary error about du not being assigned.
5. This code:
tau= 1:20; for tau=1:20 u(tau)=1; end
can be replaced by this:
u = ones(1, 20);
6. Since u is 1 for any tau, this code probably does not do what you expect:
if(u(tau)>b/l) f(u(tau))=u(tau)-b/l; end if(u(tau)> -b/l && u(tau)<b/l) f(u(tau))=0; end if(u(tau)<-b/l) f(u(tau))=u(tau)+b/l; end
You're basically setting f(1) to something.
On the plus side though, you did explain the initial variables and eve gave their units. (Don't know what "pairin" means though.)