1 close all; 2 force = 8000; % lbs 3 stringer_A = 0.5; % in^2 4 thickness = 0.04; % in 5 6 top_stringers_y = 6; % in 7 middle_stringers_y = 2; % in 8 9 I = 2*stringer_A*top_stringers_y^2 + 2*stringer_A*middle_stringers_y^2; 10 11 % solve for shear stress distribution. this calc ignores the thickness of 12 % the web between teh stringers (assumes bending taken by stringers) 13 % V / (I * t) * int(y*da) 14 15 shear_top_web = force / (I*thickness) * top_stringers_y * stringer_A; 16 shear_middle_web = shear_top_web + (force / (I*thickness) * middle_stringers_y * stringer_A); 17 18 figure; grid on; hold on;set(gcf,'color',[1 1 1]); 19 20 21 plot([shear_top_web shear_top_web],[middle_stringers_y top_stringers_y],'linewidth',2); 22 plot([shear_middle_web shear_middle_web],[-middle_stringers_y middle_stringers_y],'linewidth',2); 23 plot([shear_top_web shear_top_web],[-middle_stringers_y -top_stringers_y],'linewidth',2); 24 25 plot([0 shear_top_web],[top_stringers_y top_stringers_y],'linewidth',2); 26 plot([0 shear_top_web],[-top_stringers_y -top_stringers_y],'linewidth',2); 27 plot([shear_middle_web shear_top_web],[middle_stringers_y middle_stringers_y],'linewidth',2); 28 plot([shear_middle_web shear_top_web],[-middle_stringers_y -middle_stringers_y],'linewidth',2); 29 xlabel('shear stress (lb/in^2)','fontsize',16,'fontweight','bold');ylabel('Distance from Center (in)','fontsize',16,'fontweight','bold') 30 set(gca,'FontSize',16,'fontweight','bold'); 31 32 %Alternate approach.. compute change in bending stress at each stringer to 33 %find the change in shear load 34 35 %at top stringer 36 d_sigma = force * top_stringers_y / I; %(lbs/in^2) 37 d_force_top = d_sigma * stringer_A; 38 39 %at middle stringer.. 40 d_sigma = force * middle_stringers_y / I; %(lbs/in^2) 41 d_force_middle = d_force_top + d_sigma*stringer_A; 42 43 %check if load balances 44 check_load = 2*d_force_top*4 + d_force_middle*4; 45 46 47 48