M. Cinefra

Bio: M. Cinefra is an academic researcher from Instituto Politécnico Nacional. The author has contributed to research in topics: Metamaterial & Parametric statistics. The author has an hindex of 1, co-authored 1 publications receiving 2 citations.

Multidirectional grading influence on static/dynamic deflection and stress responses of porous FG panel structure: a micromechanical approach

Abstract: This is the first time the multidirectional-graded porous panel structure modeled numerically using an equivalent single-layer higher-order polynomial model considering the cubic variation of extensional displacement to maintain the necessary stress/strain. The effect of porosity (even and uneven distributions) and variable grading patterns also included achieving the generality. Further, the deflection and stress values, the proposed bidirectional functionally graded (2D-FG) structure, are predicted under the variable loadings, i.e. static and dynamic. Three different types of grading pattern, i.e. power-law, exponential and sigmoid are introduced by varying the material constituents along their principal material axes (longitudinal and transverse). The current numerical solutions (deflection and stress) are obtained through a customized computer code (prepared in MATLAB), under the influences of the static and time-dependent loadings utilizing the higher-order finite element formulations. The dynamic deflections are obtained through the constant acceleration type Newmark’s time-integration steps. The predicted result accuracy is checked by comparing the previously published values in literature and different simulation models (ANSYS and ABAQUS). Besides, the batch input technique is adopted for the simulation material models for both the ANSYS and ABAQUS. Moreover, the python scripting is adopted first time to modify ABAQUS input files for the present 2D graded structure. The influential structure input parameter (power-law exponents, thickness ratio, aspect ratio, end conditions, geometry and curvature ratio) is varied to compute a few final responses (deflection and stress data) of multidirectional FG structure via the derived mathematical model and the final understandings listed the details.

Band gap characteristics of two-dimensional functionally graded periodic grid structures with local resonators

Abstract: Abstract This paper aims to control the in-plane wave propagation characteristics of two-dimensional functionally graded periodic grid structures by adding local resonators made of the spring oscillator. The in-plane wave dispersion relations of the periodic grid structures with local resonators are calculated by spectral element method combined with Bloch theorem. Meanwhile, the effectiveness of the band gap calculation method is verified by the vibration transmission of the finite-length grid structures calculated based on spectral element method and finite element method. According to the spectral element method, the spectral stiffness matrix of the functionally graded beam element is established at first, then assembled with the additional stiffness matrix of the spring oscillator subsystem to obtain the complete spectral stiffness matrix of the functionally graded oscillator coupled beam. Finally, the whole stiffness matrix of grid structures with local resonators can be obtained by the coordinate transformation matrix, to form the in-plane wave dispersion relations equation based on the Bloch periodic boundary conditions. In addition, the effects of structural and material parameters on the in-plane wave propagation characteristics are analyzed, which can be applied to the vibration reduction design of periodic grid structures.

Large amplitude vibration analysis of a non-uniform beam under arbitrary boundary conditions based on a constrained variational modeling method

Abstract: A constrained variational modeling method to predict the static and dynamic behaviors of the large deflection non-uniform beam under arbitrary boundary conditions is proposed in this paper. The non-uniform beam is divided into several uniform segments. The geometrically exact formulation is employed to describe the large deformation beam segment, and displacement and rotation variables are expressed independently to avoid the shear-locking phenomenon. The strain and kinetic energy of the segment are then derived without order truncation of the geometrical non-linearity. The nonlinear relations of motion quantities and the boundary conditions of non-uniform adjacent segments are converted into additional constraint functionals. Thus, the arbitrary boundary conditions can be easily applied on the large deflection beam without altering the beam admissible functions in the present formulation. The penalty functional method and extended Hamilton’s principle are employed to obtain the governing equations eventually. A series of numerical examples are carried out to show the accuracy and efficiency of the proposed method by comparing the present results with the data in literature or calculated with nonlinear finite element method code. Moreover, the flexibility of the present formulation with arbitrary boundary conditions is exhibited with a series of parametric study. The effect of step location, step length, boundary axial and rotational stiffness on the frequency non-linearity is further studied.