Numerical Analysis of a Beam
The Problem Use several numerical analysis tools to calculate tip deflection and compare accuracies F L
Euler-Bernoulli beam theory Simplification of the linear theory of elasticity which relates loads to deflections in beams Beam theory governing equation Often, u=u(x), w=w(x), and EI is constant, yielding curve u(x) describes deflection u of the beam at some position x, and w is the distributed load Shear Force Bending Moment Slope Deflection
Boundary conditions x=o (fixed end) x=L (free end) F L
Governing ODE
Inputs Material properties F E=200x10^9 Pa I=6.7x10^-5 m^4 L=6m F=1000 N F L
Boundary conditions 0<=x<=L IVP v(x=0)=0 v’(x=L)=slope F L
Methods for comparison Numerical Differentiation Backward Euler Method RK4 FEM (NASTRAN/PATRAN) exact
Numerical Differentiation Results
Dormand and Prince (RK5) ODE system
RK4 Results ODE system
FEM Results
Exact Solution
Results Summary Method Max Tip Displacement % Error Numerical Differentiation .005379m 0.11 RK5 .005371m 0.037 RK4 FEM .005350m 0.428 Exact Solution .005373m 0.00
Animation of Deflection diving board\animation.m *courtesy of University of Wyoming Electrical and Computer Engineering Dept
References Riley,W.,Sturges,L.,& Morris, D. (1999). Mechanics of Materials. New York University of Wyoming Electrical and Computer Engineering Dept. (2008). Beam Deflection. From http://www.eng.uwyo.edu/classes/matlabanimate/StaticBeam/cantileverbeamoneload.m Kwon, Y., & Bang, H. (2000). The Finite Element Method. Florida.