Project 3- Instability of Beams

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Summary/Introduction The purpose of this project was to find at what critical weight or load being applied to one end of a column or a vertical beam will cause the beam to buckle or lose its shape. This project was composed of four different scenarios of how a column can be loaded. The four are both ends being pinned, both ends being fixed, one end being fixed and the other pinned while the beam had a variable cross section, and the beam lying on an elastic foundation. During each different scenario, we were asked to find the general solution to the differential equation (DE) that gave us the deflection of the beam and to try to solve for as many constants as we could with our given initial conditions (IC). We were also asked to find the critical load at which the beam will buckle. This project thought us that different settings will cause different deflection results on a column along with different critical loads. Results Throughout the project, we made the assumption that the beam had a negligible mass that would not affect the deflection. In real life, the weight would lower the critical load that makes the beam buckle. The solution of the DE, v(x), throughout is the path of deflection of the beam due to a load being applied. Part I: Simply Supported Ends In this scenario, the ends of the beam cannot move laterally or vertically but are allowed to bend. All calculations for this problem can be found in Appendix A. The deflection of our column could be found by solving the DE in Equation (1). EI v"+Pv=0; v(0)=v(L)=0 (1) Part I, Exercise 1: We found the general solution of the DE. In this part of the project and in the next, we assumed that the elastic modulus of the beam, E, and the area moment of inertia, ... ... middle of paper ... ...e variables r=5 cm into I and E=200*109 GPa, I, and k=1,000,000 N/m into β. We set P=1 for Equation (23) in order to graph the deflection of the beam in Figure 5. v(x)=e^(-0.710371x) {P/(8*〖0.710371〗^3 )∙cos(0.710371x)+P/(8*〖0.710371〗^3 )∙sin⁡(0.710371x) } (23) Figure 5. Deflection of beam IV.3 which sits on a bed of springs. Part IV, Exercise 4: This exercise required us to find v(0) and v’’(0) then use MATLAB and ode45 to solve the IVP and compare it to our graph in IV.3. We get v(0)= 0.348702392610958 and v’’(0)= -0.351928938921180. Using the ode45 solver on MATLAB we acquired a graph of v(x). Figure 6. Deflection of the beam found using ode45. The two graphs do not seem to be different. They have the same shape and are situated on the same scale. They are not shown to be unstable and only small sections of the graphs actually deviate from each other.

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