Error message, Equations of one or more components may be dependent or inconsistent in simscape model.

component bilinear_model

nodes

r = foundation.mechanical.translational.translational;

c = foundation.mechanical.translational.translational;

end

parameters

k1 = {1800000,'N/m'};

k2 = {600000,'N/m'};

dy = {0.0053,'m'};

ft = {5500,'N/m'};

fy = {9540,'N'};

un = 1;

tau = {1,'s'};

u0 = {0,'m'};

end

variables

x = {value = { 0, 'm'}, priority = priority.high}; % Deformation

f = {0,'N'};

v = {0,'m/s'};

d_upper = {0,'m'};

d_lower = {0,'m'};

x0 = {0,'m'};

f0 = {0,'N'};

end

branches

f : r.f -> c.f;

end

equations

d_upper == 1/(k1-k2)*(k1*x0-f0-k2*fy/k1+fy);

d_lower == 1/(k1-k2)*(k1*x0-f0+k2*fy/k1-fy);

if x < d_lower

f == k2*(x+(fy/k1))-fy;

elseif x > d_upper

f == k2*(x-(fy/k1))+fy;

else

f == k1*(x-x0)+f0;

end

v == r.v-c.v;

v == x.der;

x0 == x;

f0 == f;

end

end

I specify the bilinear spring in simscape block, to simulate the bilinear specimen.

When I connect to the hydralic system and run, I got the error message.

This is the bilienar model in Matlab bleow, it works perfectly.

function [obj,f1] = dispLoad_bilinear(obj,d1)

k1 = obj(1);

k2 = obj(2);

dy = obj(3);

d0 = obj(4);

f0 = obj(5);

status = obj(6);

fy = obj(7);

% 1) Intersecting x Coordiates

d_upper = 1/(k1-k2)*(k1*d0-f0-k2*fy/k1+fy);

d_lower = 1/(k1-k2)*(k1*d0-f0+k2*fy/k1-fy);

% 2) Determination of x1

if d1<d_lower

f1 = k2*(d1+fy/k1)-fy;

obj(6) = 2;

elseif d1>d_upper

f1 = k2*(d1-fy/k1)+fy;

obj(6) = 2;

else

f1 = k1*(d1-d0)+f0;

end

obj(4) = d1;

obj(5) = f1;

Answer 1

[Anurag Ojha]

Hello Huang

The cause of error “Steady state solve failed to converge” could be due to the algebraic loops in your model.

To detect them, please go to Configuration Parameters >> Diagnostics and set Algebraic Loop to 'error'. That will point to the block is causing it.

To solve it, you can place a Unit Delay block in the feedback to the block that is causing the error.

Also, try unchecking the "start simulation from steady state" box under Solver Configuration block.

I hope this helps you to resolve the error!