2 variables, second order differencial equation system

 function dy1dt = two_mass_spring_1(t,y1)
%UNTITLED3 Summary of this function goes here
%   Detailed explanation goes here
M1=2.66; M2=2.74; B1=0.3169; B2=0.7748; K1=317.0814;
F=11.2231; R=14.6343; Wr=18.7629;
dy1dt=[y1(2); (B1*y1(2)+K1*y1(1)+B2*y1(2)-B2*y2(2)/M1)];
dy2dt=[y2(2); (F-B2*y2(2)+B2*y1(2))/M2];
function dy2dt = two_mass_spring_2(t,y2)
%UNTITLED3 Summary of this function goes here
%   Detailed explanation goes here
M1=2.66; M2=2.74; B1=0.3169; B2=0.7748; K1=317.0814;
F=11.2231; R=14.6343; Wr=18.7629;
dy2dt=[y2(2); (F-B2*y2(2)+B2*y1(2))/M2];
end
clear all
close all
clc
tspan=[0 300];
y_0 = [-0.07 0]; 
[time,yout]=ode45('two_mass_spring_1',tspan,y_0);
figure
subplot(2,1,1)
plot(time, yout(:,1),'r'); grid on;
xlabel('Time, s')
ylabel('Displacement, m')
title('Mass on spring system free oscillating motion')
subplot(2,1,2)
plot(time, yout(:,2),'b'); grid on
xlabel('Time, s')
ylabel('Velocity, m/s')

M_1=2.66, M_2=2.74, B_1=0.3169, B_2=0.7748, k_1=317.0814, F=11.2231

M_1 y_1^''+ B_1 y_1^'+ k_1 y_1+B_2(y_1^'-y_2^') = 0 M_2 y_2^''+B_2(y_2^'-y_1^') = F

I solve 1 variables, second order differencial equation system but 2 variables cannot solve.. How can i solve this equation?

Answer 1

[Torsten]

Implement the following system with four unknown functions:

dy(1)/dt = y(2)
dy(2)/dt = -(B_1*y(2)+k_1*y(1)+B_2*(y(2)-y(4)))/M_1
dy(3)/dt = y(4)
dy(4)/dt = (F-B_2*(y(4)-y(2)))/M_2

Here,

y(1)=y_1, y(2)=y_1', y(3)=y_2, y(4)=y_2'

Best wishes

Torsten.