Element Analysis Of Composite Structures Research Articles

Structural topology optimization of three-dimensional multi-material composite structures with finite deformation

In this work, an explicit three-dimensional (3D) topology optimization approach is presented for multi-material composite structures accounting the finite deformation effect. The proposed method employs different sets of 3D Moving Morphable Voids (MMVs) to identify each phase material, resulting in explicit geometric descriptions of the optimized composite structures and a reduction in the number of design variables. The decoupling between the topology description and finite element analysis of composite structures enables the removal of redundant degrees of freedom, thereby mitigating the convergence issue of finite deformation analysis caused by low-density elements and leading to significant computational savings. Numerical experiments of composite structures with two- and three-phase materials are optimized to validate the accuracy and efficiency of the proposed method. The results demonstrate that, under finite deformation, the distribution of each phase material in optimized 3D composite structures is significantly affected by the amplitude of external loads, and the optimized layout could be quite different from its counterpart under small deformation assumption.

Stochastic Finite Element Analysis of Composite Structures with Partially Restrained Connections under Earthquake Loads

The stochastic analysis of composite structures with partially restrained (PR) connections under seismic loads present some interesting and challenging issues to practicing engineers. This paper proposes an efficient, robust, and accurate method for stochastic finite element analysis of concrete–steel composite structures allowing for PR connections. These are followed by suitable numerical example which indicates that employment of such a stochastic finite element analysis. The Kocaeli earthquake in 1999 is considered as a ground motion. The connections parameters and material properties are random variables. It is essential to properly consider the PR connections in the stochastic dynamic analysis and design of the steel-concrete composite structures since design forces change significantly. The assumption that the connections are rigid, which is routinely used in the application, is not proper. The effect of the variability connection stiffness on the composite structures responses is sufficiently important for consideration in structural safety.

Stochastic finite element analysis of composite structures based on mesoscale random fields of material properties

The linking of microstructure uncertainty with the random variation of material properties at higher scales is of paramount importance in the framework of the stochastic finite element method (SFEM). An efficient computational scheme has been recently proposed by the authors for the determination of mesoscale random fields for the apparent properties and of the RVE size of particle-reinforced composites based on computer-simulated images of their microstructure. The proposed approach exploits the excellent synergy of the extended finite element method (XFEM) and Monte Carlo simulation in order to analyze the microstructure models and obtain statistical information (probability distribution, correlation structure) for the apparent properties of the composite in each mesoscale size. In this paper, sample functions of the statistically homogeneous mesoscale random fields are generated using the spectral representation method in conjunction with translation field theory. Moreover, micro-mechanically consistent (lower and upper) bounds on the macroscopic response of composite structures are computed in the framework of SFEM. Useful conclusions are derived regarding the effect of particle/matrix stiffness ratio on the probabilistic characteristics of the mesoscale random fields as well as the influence of mesoscale size on the response variability.

Assessment of the effect of microstructural uncertainty on the macroscopic properties of random composite materials

The linking of microstructural uncertainty with the random variation in the response of heterogeneous structures at the macroscale is particularly important in the framework of the stochastic finite element method. In this work, the effect of uncertainty in the constituent material properties and the geometry of the microstructure, on the macroscopic properties of composite materials is assessed through computational homogenization. Based on Hill–Mandel homogeneity condition, the homogenization procedure utilizes the excellent synergy of the extended finite element method and the Monte Carlo simulation. In this way, the computation of the statistical characteristics of the homogenized elasticity tensor of random composite materials reinforced with arbitrarily shaped inclusions is performed in a computationally efficient manner. The effect of stochastic variation in the elastic properties of the constituents as well as the effect of inclusion shape on the statistical characteristics of the homogenized elasticity tensor is assessed through probabilistic sensitivity analysis. A comparison is performed with regard to the relative influence of material and geometrical uncertainty which are considered separately. More realistic results are obtained by considering simultaneously material and geometrical uncertainty in the microstructural modeling of composite materials. The results can be further exploited in the stochastic finite element analysis of composite structures where material properties with random characteristics obtained by the presented multiscale homogenization procedure will be assigned to each finite element.

Stochastic finite element analysis of composite structures based on material microstructure

The linking of microstructure uncertainty with the random variation of material properties at the macroscale is particularly needed in the framework of the stochastic finite element method (SFEM) where arbitrary assumptions are usually made regarding the probability distribution and correlation structure of the macroscopic mechanical properties. This linking can be accomplished in an efficient manner by exploiting the excellent synergy of the extended finite element method (XFEM) and Monte Carlo simulation (MCS) for the computation of the effective properties of random two-phase composites. The homogenization is based on Hill’s energy condition and involves the generation of a large number of random realizations of the microstructure geometry based on a given volume fraction of the inclusions and other parameters (shape, number, spatial distribution and orientation). In this paper, the mean value, coefficient of variation and probability distribution of the effective elastic modulus and Poisson ratio are computed taking into account the material microstructure. The effective properties are used in the framework of SFEM to obtain the response of a composite structure and it is shown that the response variability can be significantly affected by the random microstructure.

Global sensitivity analysis of expensive models using sparse grids with applications to laminated composite structure

Four methods for global sensitivity analysis are studied with respect to their applicability in the finite element analysis of composite structures: (1) sensitivities based on the variance conditional expectation involving experimental design, (2) Morris' elementary effects method (including recent improvements to effective trajectory selection), (3) Sobol's main and total sensitivity indices, and (4) the root mean square of approximate derivatives at sampled points. The sensitivities of the first ten natural frequencies to the composite material properties as well as to the ply stack are determined. The methods are compared and an assessment of their applicability is made in the case of a fairly large number (d > 25) of uncertain parameters.

FEA of Solid Stream Coupling Field Formed by Automobile Engine Cylinder Head and Cylinder Head Gasket

This paper focuses on discussing the application of FEA theory and method in calculation of composite structure strength between engine cylinder head and head gasket. Based on finite element analysis software, the integrated system of 3D CAD/CAE application software was developed for the finite-element analysis of the composite structure consisting of engine cylinder head and head gasket. By using the software system, several jobs, such as working condition analysis from preloading to outburst operation, structural analysis and steady-state thermal analysis, and thermo-structure coupling analysis, were carried out. The results studied in this paper provide a new idea and method for the finite element analysis of composite structure between engine cylinder head and head gasket.

Multiscale composite FEM modeling

A two-stage (macro-micro) finite element analysis of composite structure is presented in this paper. A global-local (meso) modeling method is proposed in order to reduce the computational effort usually required to analyze such structures. The loading of the micro-cell is obtained from the macro model. To apply an appropriate mesh in the global model the strain energy in a beam under pure bending moments is calculated and then compared with the numerical results. The simulation of the three-point bending test of CFRP (carbon fibre reinforced polymer) is presented as an example of the use of the developed algorithm. Standard elements from the commercial FEM analysis software package Marc are used to perform the non-linear stress analysis.

Ultimate Strength Failure Probability Estimation of Composite Structures

A probabilistic progressive failure analysis method is opposed to estimate the ultimate strength failure probability of composite structures by combining the system reliability method with deterministic progressive failure analysis. Ply-level failure modes such as matrix cracking, fiber breakage and delamination, are considered. Probabilistically dominant ply-level failure sequences leading to overall system failure are identified using branch and bound method. The system failure probability is estimated through the union of significant failure sequences. The method is formulated in the context of three-dimensional finite element analysis of composite structures, using the first-order shear deformation theory.

Finite element analysis of composite structures with smart constrained layer damping

In the present study, the finite element formulation is proposed for the dynamic analysis of smart composite structures. Based on visco-piezoelectricity, the numerical procedures are developed to analyze dynamic responses of composite structures with piezoelectric sensors and actuators as well as viscoelastic damping layers. A solid element with Allman's rotation is used since it is more efficient for structures of arbitrary shape and can avoid compatibility discrepancies between plate and solid elements. Numerical examples are presented in order to verify the accuracy convergence of the present formulation and to demonstrate its usefulness for and applicability to solutions of dynamic responses of smart structures.

Finite element analysis of composite structures

A study of commercially available systems for the analysis of composite structures will illustrate that software and hardware technology is deficient in power and functionality for today's engineering requirements. This situation leads to analysis strategies which are unwieldy and involve approximations which would be unnecessary, given the proper tools. This paper examines the general topic of finite element analysis of composite structures and highlights areas of difficulty where further research and development is necessary. These developments are discussed in the context of software and hardware trends. The paper should also serve as a useful introduction to the topic area and hopefully set the scene for some of the following papers in this special issue.

Probabilistic nonlinear finite element analysis of composite structures

A probabilistic finite element analysis procedure for laminated composite shells is developed. A total Lagrangian finite element formulation, employing a degenerated three-dimensional laminated composite shell element with the full Green-Lagrange strains and first-order shear deformable kinematics, is used. The first-order second-moment technique for probabilistic finite element analysis of random fields is employed, and results are presented in the form of mean and variance of the structural response. Reliability calculations are made by using the first-order reliability method combined with sensitivity derivatives from the finite element analysis. Both ply-level and micromechanics-level random variables are incorporated, the latter by means of the Aboudi micromechanics model. Two sample problems are solved to verify the accuracy of the procedures developed and to quantify the variability of certain material type/structure combinations. In general, the procedure is quite effective in determining the response statistics and reliability for linear and geometric nonlinear behavior of laminated composite shells.

Finite element analysis of composite structures containing distributed piezoceramic sensors and actuators

A finite element formulation is presented for modeling the dynamic as well as static response of laminated composites containing distributed piezoelectric ceramics subjected to both mechanical and electrical loadings. The formulation was derived from the variational principle with consideration for both the total potential energy of the structures and the electrical potential energy of the piezoceramics. An eight-node three-dimensional composite brick element was implemented for the analysis, and three-dimensional incompatible modes were introduced to take into account the global bending behavior resulting from the local deformations of the piezoceramics. Experiments were also conducted to verify the analysis and the computer simulations. Overall, the comparisons between the predictions and the data agreed fairly well. Numerical examples were also generated by coupling the analysis with simple control algorithms to control actively the response of the integrated structures in a closed loop.