Stress Analysis of Composite Cylindrical Shells with an Elliptical Cutout

A special-purpose, semi-analytical solution method for determining the stress and deformation fields in a thin laminated-composite cylindrical shell with an elliptical cutout is presented. The analysis includes the effects of cutout size, shape, and orientation; non-uniform wall thickness; oval-cross-section eccentricity; and loading conditions. The loading conditions include uniform tension, uniform torsion, and pure bending. The analysis approach is based on the principle of stationary potential energy and uses Lagrange multipliers to relax the kinematic admissibility requirements on the displacement representations through the use of idealized elastic edge restraints. Specifying appropriate stiffness values for the elastic extensional and rotational edge restraints (springs) allows the imposition of the kinematic boundary conditions in an indirect manner, which enables the use of a broader set of functions for representing the displacement fields. Selected results of parametric studies are presented for several geometric parameters that demonstrate that analysis approach is a powerful means for developing design criteria for laminated-composite shells

Multiphysics discovery with moving boundaries using Ensemble SINDy and Peridynamic Differential Operator

This study proposes a novel framework for learning the underlying physics of phenomena with moving boundaries. The proposed approach combines Ensemble SINDy and Peridynamic Differential Operator (PDDO) and imposes an inductive bias assuming the moving boundary physics evolve in its own corotational coordinate system. The robustness of the approach is demonstrated by considering various levels of noise in the measured data using the 2D Fisher-Stefan model. The confidence intervals of recovered coefficients are listed, and the uncertainties of the moving boundary positions are depicted by obtaining the solutions with the recovered coefficients. Although the main focus of this study is the Fisher-Stefan model, the proposed approach is applicable to any type of moving boundary problem with a smooth moving boundary front without a mushy region. The code and data for this framework is available at: https://github.com/alicanbekar/MB_PDDO-SINDy.Comment: 26 pages, 22 figures, submitted to Proceedings of the Royal Society

Stress Analysis of Composite Cylindrical Shells With an Elliptical Cutout

A special-purpose, semi-analytical solution method for determining the stress and deformation fields in a thin laminated-composite cylindrical shell with an elliptical cutout is presented. The analysis includes the effects of cutout size, shape, and orientation; nonuniform wall thickness; oval-cross-section eccentricity; and loading conditions. The loading conditions include uniform tension, uniform torsion, and pure bending. The analysis approach is based on the principle of stationary potential energy and uses Lagrange multipliers to relax the kinematic admissibility requirements on the displacement representations through the use of idealized elastic edge restraints. Specifying appropriate stiffness values for the elastic extensional and rotational edge restraints (springs) allows the imposition of the kinematic boundary conditions in an indirect manner, which enables the use of a broader set of functions for representing the displacement fields. Selected results of parametric studies are presented for several geometric parameters that demonstrate that analysis approach is a powerful means for developing design criteria for laminated-composite shells

Peridynamics for bending of beams and plates with transverse shear deformation

Progressive failure analysis of structures is still a major challenge. There exist various predictive techniques to tackle this challenge by using both classical (local) and nonlocal theories. Peridynamic (PD) theory (nonlocal) is very suitable for this challenge, but computationally costly with respect to the finite element method. When analyzing complex structures, it is necessary to utilize structural idealizations to make the computations feasible. Therefore, this study presents the PD equations of motions for structural idealizations as beams and plates while accounting for transverse shear deformation. Also, their PD dispersion relations are presented and compared with those of classical theory

Peridynamic modeling of composite laminates under explosive loading

High velocity impact and shock or blast responses are a critical design characteristic determining sizing of composite parts and, ultimately, weight savings. This study demonstrates the applicability of peridynamics to accurately predict nonlinear transient deformation and damage behavior of composites under shock or blast type s of loadings due to explosions. The peridynamic predictions correlate well with the experimental results available in the literature. Therefore, peridynamics provides the ability to predict residual strength and durability for improving structural designs of composites under such loading conditions

Peridynamic modeling of composite laminates under explosive loading

Peer reviewedPostprin

Peridynamic modeling of thermo-oxidative damage evolution in a composite lamina

Surface oxidation degrades the durability of polymer marix composites operating at high temperatures due to the presence of strong coupling between the thermal oxidation and structural damage evolution. The mechanism of oxidation in polymer matrix composites leads to shrinkage and damage growth. The thermo-oxidative behavior of composites introduces changes in diffusion behavior and mechanical response of the material. This study presents the derivation of peridynamic formulation for the thermo-oxidative behavior of the polymer matrix composites. As a demonstration purposes, isothermal aging of a unidirectional composite lamina is presented by using peridynamics. Oxidation contributed to the damage growth and its propagation

Moisture diffusion modelling by using peridynamics

The moisture concentration in electronic packages can be determined based on the “wetness” approach. The wetness parameter representing the ratio of the moisture concentration with respect to the saturated concentration value of the material is continuous along dissimilar material interfaces. If the saturated concentration value is not dependent on temperature or time, the wetness equation is analogous to the standard diffusion equation whose solution can be constructed by using any commercial finite element analysis software. However, the time dependency of saturated concentration requires special treatment under temperature dependent environmental conditions such as reflow process. The saturated concentration values of most polymer materials in electronic packages are mostly dependent on temperature. As a result, the wetness equation is not directly analogous to the standard diffusion equation. This study presents peridynamic solution of the wetness equation with time dependent saturated concentration. The approach is computationally efficient as well as easy to implement without any iterations in each time step. The implementation is achieved by using the traditional elements and solvers available in a commercial finite element software

A novel finite element technique for moisture diffusion modeling using ANSYS

This study presents a novel modeling approach for wetness and moisture concentration in the presence of time dependent saturated moisture concentration by employing the traditional ANSYS thermal and surface effect elements. The accuracy of the present approach is established by comparison with those of the existing ANSYS "diffusion" and "coupled field" elements as well as peridynamic theory. The comparison concerns the desorption process in a fully saturated bar made of two different materials with equal and unequal values of solubility activation energy in the presence of time dependent saturated moisture concentration under uniform and nonuniform temperature conditions. The results from the present approach agree well with those of peridynamics and ANSYS "coupled field" elements if the diffusivity is specified as time dependent. Significant deviation occurs if the diffusivity is specified as temperature dependent. The ANSYS "diffusion" element is applicable only for uniform temperature, and deviation becomes significant especially for unequal values of solubility activation energy