Fem Analysis Of Composite Wing Structure And Micro-Laminated Beam Theory

By using a simulation model of UAV wing as half-beam type of all-metal and Equivalent Stiffness Design method, models of UAV wing as half-composite and full-composite are established. Both the triangular shell element and the quadrilateral shell element with different mesh density are adopted for analysis of FEM. The weights of the models of half-composite and full-composite wing are used to compare with the all-metal wing. Calculating results show that: (1) Half-beam wing skin has a higher load-bearing capacity; (2) The full composite wing is nearly 50% weight loss from all-metal wing; (3) When the convergence of FEM evaluated with the maximum displacement, for the number of node is 1974, the results of triangular and quadrilateral shell elements of the present model move towards each other, the requirement of convergence can be satisfied; (4) When the convergence of FEM evaluated with the maximum stress, for the number of node is 1974, the result of present model has not converge, and stress values calculated with triangular and quadrilateral shell element increases with the number of nodes. When the number of node is 19866, the result can be satisfied.. Consequently, the designing will be unsafe due to lower stress result obtained by displacement convergence.Based on a modified couple stress theory, a model for composite laminated Reddy beam is developed. The theory contains in the rotation-displacement as dependent variable and only one micro- material’s constant. The present model of beam can be viewed as a simplified couple stress theory in engineering mechanics. An example as a cross-ply simply supported beam subjected to cylindrical bending loads is adopted. Numerical results show that the present beam model can capture the scale effects of microstructure, and the deflections and stresses of the present model of couple stress beam are smaller than that by the classical beam model. Additionally, the present model can be reduced to the composite laminated Timoshenko beam model, isotropic Timoshenko beam model of couple stress theory, composite laminated Bernoulli-Euler beam model of couple stress theory and isotropic Bernoulli-Euler beam of couple stress theory.