Showing papers by "Alberto Milazzo published in 2023"

Buckling and post-buckling of variable stiffness plates with cutouts by a single-domain Ritz method

Abstract: Structural components with variable stiffness can provide better performances with respect to classical ones and offer an enlarged design space for their optimization. They are attractive candidates for advanced lightweight structural applications whose functionalities often impose the presence of cutouts that requires accurate and effective analysis for their design. In the present work, a single-domain Ritz formulation is proposed, implemented and validated for the analysis of buckling and post-buckling behaviour of variable stiffness plates with cutouts. The plate model is based on the first-order shear deformation theory with nonlinear von Karman strain–displacement relationships. The plate generalized displacements are approximated with trial functions built as products of one-dimensional Legendre orthogonal polynomials. The non linear governing equations system is then deduced from the stationarity of the energy functional; the involved matrices are numerically computed by a special integration algorithm based on the implicit description of the cutout via suitable level-set functions. The formulation has been implemented in a computer code which has been used to validate the method through comparison with literature solutions for variable angle tow laminates with circular cutouts. Several investigations on buckling and post-buckling behaviour of variable angle tow composite plates with cutouts having different shapes and dimensions are then presented to illustrate the approach capabilities, provide benchmark results and point out features and design opportunities of the variable stiffness concept for the buckling and post-buckling design of advanced lightweight structures. • Variable stiffness plates with cut-outs are modeled via a single-domain Ritz method • Quadrature rules are based on the description of the cut-out via level set functions • Buckling and post-buckling of variable angle tow composite laminates are investigated

Coupled VEM-BEM approach for isotropic damage modelling in composite materials

Abstract: Numerical prediction of composite damage behaviour at the microscopic level is still a challenging engineering issue for the analysis and design of modern materials. In this work, we document the application of a recently developed numerical technique based on the coupling between the virtual element method (VEM) and the boundary element method (BEM) within the framework of continuum damage mechanics (CDM) to model the in-plane damage evolution characteristics of composite materials. BEM is a widely adopted and efficient numerical technique that reduces the problem dimensionality due to its underlying formulation. It substantially simplifies the pre-processing stage and decreases the computational effort without affecting the solution’s accuracy. VEM is a recent generalization to general polygonal mesh elements of the finite element method that ensures noticeable simplification in the data preparation stage of the analysis, notably for computational micro-mechanics problems, whose analysis domain often features complex geometries. The numerical technique has been applied to artificial microstructures, representing the transverse section of composite material with stiffer circular-shaped inclusions embedded in a softer matrix. BEM is used to model the inclusions that are supposed to behave within the linear elastic range, while VEM is used to model the surrounding matrix material, developing nonlinear behaviours. Numerical results are reported and discussed to validate the proposed method.