find the intersection of the four corner and trim the value out of the corner

I have used the four lines to plot the figure below. I would like to know how to find the intersection and trim the value out of the corner. Please see my code below

clc
clear

grid on
syms stress1 stress2 shear12
SL_Ts=1800;
SL_Cm=1400;
ST_Ts=40;
ST_Cm=230;
SLT=100;

y1=((stress1-SL_Ts)/0.3);
y2=0.01875*stress1+ST_Ts;
y3=((stress1+SL_Cm)/0.3);
y4=0.01875*stress1-ST_Cm;

figure(1)
hold on
fplot(y1,[1700,1900],'b','LineWidth',1.5)
fplot(y2,[-1500,1900],'b','LineWidth',1.5)
fplot(y3,[-1500,-1200],'b','LineWidth',1.5)
fplot(y4,[-1500,1900],'b','LineWidth',1.5)
ylim([-400 200])
xlim([-2000 3800])

Answer 1

[Star Strider]

Solve for the intersections, then plot to those limits —

grid on
syms stress1 stress2 shear12
SL_Ts=1800;
SL_Cm=1400;
ST_Ts=40;
ST_Cm=230;
SLT=100;

y1=((stress1-SL_Ts)/0.3);
y2=0.01875*stress1+ST_Ts;
y3=((stress1+SL_Cm)/0.3);
y4=0.01875*stress1-ST_Cm;

y1y2 = double(solve(y1 == y2))                                 % 'y1' 'y2' Intersection

y1y2 = 1.8223e+03

y1y4 = double(solve(y1 == y4))                                 % 'y1' 'y4' Intersection

y1y4 = 1.7408e+03

y2y3 = double(solve(y2 == y3))                                 % 'y1' 'y4' Intersection

y2y3 = -1.3959e+03

y3y4 = double(solve(y3 == y4))                                 % 'y1' 'y4' Intersection

y3y4 = -1.4773e+03

figure(1)
hold on
fplot(y1,[y1y4 y1y2],'b','LineWidth',1.5)
fplot(y2,[y2y3,y1y2],'b','LineWidth',1.5)
fplot(y3,[y3y4,y2y3],'b','LineWidth',1.5)
fplot(y4,[y3y4,y1y4],'b','LineWidth',1.5)
ylim([-400 200])
xlim([-2000 3800])

Success!

.

[Mark]

Thanks a lot! Your way is really useful!

[Star Strider]

As always, my pleasure!

Thank you!

.