Optimal Fiber Orientation Research Articles

Isogeometric approach for buckling analysis of CNT-reinforced composite skew plates under optimal CNT-orientation

This paper presents a first know study of the effect of orientation angle of carbon nanotubes (CNTs), embedded in a single-ply polymer-based CNT-reinforced composite, on buckling behavior of skew plates using an isogeometric analysis. The plate model is based on Reddy’s higher-order shear deformation theory (HSDT). Four in-plane loading conditions together with simply supported and cantilevered boundary conditions have been considered. The optimum CNT fiber orientations for CNT-reinforced composite rhombic plates with varying skew angles and boundary conditions are presented. Moreover, the effect of width-to-thickness ratio on optimum CNT orientation is explored. The results show that the efficiency of the skew plate structures can be significantly improved by simply placing the CNTs in the correct orientation.

Influence of fiber orientation on solid particle erosion of uni/multidirectional carbon fiber/glass fiber reinforced epoxy composites

This article describes the development of unidirectional and multidirectional laminated composites consisting of thermoplastic epoxy resin reinforced with glass/carbon fiber, and studies their solid particle erosion behavior under different operating conditions. The erosion rates of the unidirectional carbon fiber/epoxy composites [0°, 30°, 45°, 60°, 90°] and multidirectional glass fiber/epoxy composites ([0°/−90°/0°], [30°/−60°/30°], [45°/−45°/45°], [60°/−30°/60°], [90°/0°/90°]) were especially scrutinized based on their respective fiber orientations. In addition; the test specimens were evaluated at three different impingement angles of 30°, 60°, and 90° with an impact velocity of 34 m/s. Slightly rounded and irregular Al2O3 particles with an average diameter of 400 µm were used. An optimal fiber orientation combination was determined, which led to minimization of the erosion rate. Moreover, the variation of erosion rates with various laminate orientations were characterized by using X-ray diffraction patterns, 3D digital mapping method, and scanning electron microscopy.

A comparative evaluation of the effect of polymer chemistry and fiber orientation on mesenchymal stem cell differentiation

Bioengineered tissue scaffolds in combination with cells hold great promise for tissue regeneration. The aim of this study was to determine how the chemistry and fiber orientation of engineered scaffolds affect the differentiation of mesenchymal stem cells (MSCs). Adipogenic, chondrogenic, and osteogenic differentiation on aligned and randomly orientated electrospun scaffolds of Poly (lactic‐co‐glycolic) acid (PLGA) and Polydioxanone (PDO) were compared. MSCs were seeded onto scaffolds and cultured for 14 days under adipogenic‐, chondrogenic‐, or osteogenic‐inducing conditions. Cell viability was assessed by alamarBlue metabolic activity assays and gene expression was determined by qRT‐PCR. Cell‐scaffold interactions were visualized using fluorescence and scanning electron microscopy. Cells grew in response to scaffold fiber orientation and cell viability, cell coverage, and gene expression analysis showed that PDO supports greater multilineage differentiation of MSCs. An aligned PDO scaffold supports highest adipogenic and osteogenic differentiation whereas fiber orientation did not have a consistent effect on chondrogenesis. Electrospun scaffolds, selected on the basis of fiber chemistry and alignment parameters could provide great therapeutic potential for restoration of fat, cartilage, and bone tissue. This study supports the continued investigation of an electrospun PDO scaffold for tissue repair and regeneration and highlights the potential of optimizing fiber orientation for improved utility. © 2016 The Authors Journal of Biomedical Materials Research Part A Published by Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 2843–2853, 2016.

Optimal fiber orientation and topology design for compliant mechanisms with fiber-reinforced composites

An approach for designing compliant mechanisms with glass fiber-reinforced epoxy materials is presented to obtain the optimum fiber orientation and topology structure simultaneously in this paper. Four-node hybrid stress elements and nodal design variables are adopted to suppress the islands and checkerboard phenomenon without additive filter technology and constraint. Taking fiber orientation and relative density as design variables, minimizing the weighted linear combination of the mutual strain energy and the strain energy is considered as objective function to achieve the desired deformation and enough load-carrying capacity of compliant mechanisms with the volume constraint. The displacement field of structure is obtained by the finite element analysis, and the non-linear optimization problem is solved via the well-known method of moving asymptotes. The numerical examples of designing compliant inverters and grippers with different weighted factors are investigated to demonstrate the effectiveness of the proposed method.

Maximization of fundamental frequencies of axially compressed laminated truncated conical shells against fiber orientation

Free vibration analyses of laminated truncated conical shells subjected to axial compressive forces are carried out by employing the Abaqus finite element program. The fundamental frequencies of these truncated conical shells with a given material system are then maximized with respect to fiber orientations by using the golden section method. Through parametric studies, the influences of the end condition, shell length, shell radius ratio and the compressive force on the maximum fundamental frequencies, the associated optimal fiber orientations and the associated vibration modes are demonstrated and discussed.

Improving the mechanical performances of a multilayered plate with the orientations of its layers of fibers

We consider a symmetric composite multilayered plate whose fiber orientation varies from a layer to another. The plate model used is that of Mindlin. We are interested in determining the optimal fiber orientations that optimize, in the same time, two criteria: minimizing the compliance and maximizing the smallest eigenfrequency of vibration or minimizing both of the compliance and the smallest eigenfrequency or maximizing both of the smallest eigenfrequency and the smallest buckling load. In order to optimize one of the above criteria, a metaheuristic algorithm of Simulated Annealing type is used. While, in the case of optimizing two objectives, the Pareto front method is used. Numerical results are presented for a rectangular eight-layered plate.

Investigation of the optimal collagen fibre orientation in human iliac arteries

The distribution of collagen fibres plays a significant role in the mechanical behaviour of artery walls. Experimental data show that in most artery wall layers there are two (or more) in-plane symmetrically disposed families of fibres. However, a recent investigation revealed that some artery wall layers have only one preferred fibre direction, notably in the medial layer of human common iliac arteries. This paper aims to provide a possible explanation for this intriguing phenomenon. An invariant-based constitutive model is utilized to characterize the mechanical behaviour of tissues. We then use three different hypotheses to determine the ‘optimal fibre angle’ in an iliac artery model. All three hypotheses lead to the same result that the optimal fibre angle in the medial layer of the iliac artery is close to the circumferential direction. The axial pre-stretch, in particular, is found to play an essential role in determining the optimal fibre angle.

Multiscale topology optimization of bi-material laminated composite structures

This work describes a computational model to design bi-material composite laminates, with the objective of optimally design the structure and its material, using a multiscale topology optimization model. It assumes two scales dealing with the structural and the material levels respectively, both for analysis and design.The model is based on a hierarchical structural optimization strategy that takes into account the manufacturing process and fundamental characteristics of composite laminates to minimize the structural compliance. It assumes a mixed set of micro and macro design variables to characterize the distribution of two materials and obtain the optimal composite microstructure at the micro design level and the optimal fiber orientation at the macro level. The results obtained demonstrate that multiscale topology optimization, applied to laminated composite structures, opens the possibility for improved and innovative designs when compared with classical laminated composite design solutions. In addition, these results are helpful to gain insight into the effectiveness of the microstructure features of composite laminates.

Fiber Orientation Angles Optimization for Maximum Fundamental Frequency of Laminated Composite Plates by the Genetic Algorithm and Meshless Method

Fiber orientation angles optimization is carried out for maximum fundamental frequency of clamped laminated composite plates using the genetic algorithm. The meshless method is utilized to calculate the fundamental frequency of clamped laminated composite plates. In the present paper, the maximum fundamental frequency is an objective function; design variables are a set of fiber orientation angles in the layers. The examples of square laminated plates are considered. The results for the optimal fiber orientation angles and the maximum fundamental frequencies of the 2-layer plates are presented.

Minimize the Deflection of Laminated Composite Plates under the External Load Using Fiber Orientation Angle

Optimization of fiber orientation angle is studied to minimize the deflection of the laminated composite plates by the genetic algorithm. The objective function of optimization problem is the minimum deflection of laminated composite plates under the external load; optimization parameters are fiber orientation angle of laminated composite plates. The results for the optimal fiber orientation angle and the minimum deflection of the 4-layer plates are presented to demonstrate the validity of present method.

Fiber Orientation Angle Optimization for Minimum Stress of Laminated Composite Plates

The genetic algorithm is used to minimize the stress of the laminated composite plates by optimizing the fiber orientation angle. The objective function of optimization problem is the minimum stress in center of laminated composite plates under the external load; optimization variables are fiber orientation angle. The results for the optimal fiber orientation angle and the minimum stress of the 2-layer plates and 3-layer plates are presented.

Multi-objective design for aeroelastic flutter of laminated shallow shells under variable flow angles

A design approach is presented for the multi-objective optimal design problem of aeroelastic laminated doubly curved shallow shells. The design objective is the maximization of weighted sum of the critical aerodynamic pressures under different probability density function of flow orientations. The design variable is the fiber orientations in the layers of the symmetrically angle-ply shells. Four typical probability density functions of flow orientations are considered. Hamilton’s principle with the first-order shear deformation theory (FSDT) is used in the flutter analysis of supersonic doubly curved shallow shells. The multi-objective optimal design problem of symmetrical alternating angle-ply sequence [θ/−θ/θ/−θ]s and symmetrical arbitrary angle-ply sequence [θ1/θ2/θ3/θ4]s laminated shell structure are investigated. Finally, using a layerwise optimization approach (LOA), the optimal fiber orientation angles of supersonic laminated shells are determined to obtain the maximum design objective.

Optimizing fiber orientation in fiber-reinforced materials using efficient upscaling

We present an efficient algorithm to find an optimal fiber orientation in composite materials. Within a two-scale setting fiber orientation is regarded as a function in space on the macrolevel. The optimization problem is formulated within a function space setting which makes the imposition of smoothness requirements straightforward and allows for rather general convex objective functionals. We show the existence of a global optimum in the Sobolev space H1(Ω). The algorithm we use is a one level optimization algorithm which optimizes with respect to the fiber orientation directly. The costly solve of a big number of microlevel problems is avoided using coordinate transformation formulas. We use an adjoint-based gradient type algorithm, but generalizations to higher-order schemes are straightforward. The algorithm is tested for a prototypical numerical example and its behaviour with respect to mesh independence and dependence on the regularization parameter is studied.

Multiobjective optimization of composite cylindrical shells for strength and frequency using genetic algorithm and neural networks

Abstract In this paper, the optimal fiber orientations relative to the principle axis of composite cylindrical shell composed of four and six layers were determined so that the natural frequency and strength of the shell are optimized. For this purpose, first, the free vibration analysis of the shell was carried out based on 3D elasticity. Then, for calculation of the strength objective function, the inverse form of Tsai-Hill yield criteria was used and the functions of strength and frequency were developed in terms of fiber orientation. Once the correctness of the above solutions was ensured, the objective functions were modeled with artificial neural network (ANN). The model made was then introduced into genetic algorithm (GA) and the maximum fitness function and optimal staking sequence of the layers with respect to the fibers angles were obtained. Optimal solutions obtained by combination of ANN and GA are compared to the solutions obtained by analytical solution and GA; eventually, the tables and diagrams are presented and different fiber orientations as optimization solutions are presented as the final results of the composite shell analysis.

Design optimization of fiber-reinforced laminates for maximum fatigue life

Composite structures are usually subjected to fluctuating loads in service leading to fatigue failure. Because it is one of the main failure modes, fatigue behavior of composites has been extensively studied to be able to design fatigue-resistant composite structures. However, little attention has been paid to their design optimization under fatigue loading. In this study, a methodology is proposed to find the optimum fiber orientation angles of composite laminates under various in-plane loads to achieve maximum fatigue life. Fawaz–Ellyin’s model is used to predict the fatigue life of the laminates. A variant of simulated annealing algorithm is used as the search algorithm in the optimization procedure. A number of problems are solved to demonstrate the effectiveness of the proposed method.

BREAKING ANALYSIS OF ARTIFICIAL ELASTIC TUBES AND HUMAN ARTERY

Mechanical behaviors of artificial elastic tubes are studied to see if the fibre orientation in these vessels is optimal by comparison with those of human artery. By optimal we mean that the strengths of stretching and inflation in the vessels are equally good. Artificial thin film tubes have many applications in the food and fruit packing industry. In this paper, the wall of thin-film elastic tubes is considered as a fibre-reinforced membrane with two families of fibres and a uniform matrix material. Their mechanical properties are determined using a structure-based constitutive law. The constitutive parameters are inversely estimated from two separate uniaxial tensile tests in the circumferential and longitudinal directions. The inflation model for the elastic tubes and human common carotid artery are developed to investigate their breaking characteristics, and to explore the optimal fibre orientations. Results show that the fibre orientation has an important effect on the break behavior of the elastic tubes, and the tubes investigated are much weaker in the circumferential direction. On the other hand, the fibre orientation is close to the optimal state in the human common carotid artery.

Numerical Implementation and Finite Element Analysis of Anisotropic Hyperelastic Biomaterials - Influence of Fibers Orientation

Modeling anisotropic behavior of fiber reinforced rubberlike materials is actually of a great interest in many industrials sectors. Indeed, accurately description of the mechanical response and damage of such materials allows the increase of the lifecycle of these materials which generally evolve under several environment conditions. In this paper theoretical study and finite element analysis of anisotropic biomaterials is presented. The mechanical model adopted to achieve this study has been implemented into the finite element code Abaqus using an implicit scheme. This constitutive law has been utilized to perform some numerical simulations. The material parameters of the model have been determined by numerical calibration. One fiber family is considered in this work. Effects of the fiber orientation on the mechanical response and stiffness change of biomaterial is studied. Both the compressible and incompressible states have been taken into account. The results show firstly the capability of the model to reproduce the known results and that optimal fiber orientation can be found.

Topology and thickness optimization of laminated composites including manufacturing constraints

This paper presents a gradient based optimization method for large-scale topology and thickness optimization of fiber reinforced monolithic laminated composite structures including certain manufacturing constraints to attain industrial relevance. This facilitates application of predefined fiber mats and reduces the risk of failure such as delamination and matrix cracking problems. The method concerns simultaneous determination of the optimum thickness and fiber orientation throughout a laminated structure with fixed outer geometry. The laminate thickness may vary as an integer number of plies, and possible fiber orientations are limited to a finite set. The conceptual combinatorial problem is relaxed to a continuous problem and solved on basis of interpolation schemes with penalization through the so-called Discrete Material Optimization method, explicitly including manufacturing constraints as a large number of sparse linear constraints. The methodology is demonstrated on several numerical examples.

Analysis and optimal design for supersonic composite laminated plate

The present paper is concerned with the vibration of supersonic laminated plates with general edge conditions. The critical aerodynamic pressure for different types of laminated plate is studied by considering the thermal effects. It is found from the numerical results that, with the increase of aerodynamic pressure for different edge conditions of supersonic plates, the first critical flutter modes are different and in some cases with the increase of aerodynamic pressure the buckling occurs before the flutter. Using a layerwise optimization approach (LOA), the optimal fiber orientation angles of supersonic laminated plate are determined to obtain the maximum critical aerodynamic pressure. It clearly demonstrated that through the optimization process, one can largely raise the critical aerodynamic pressure and significantly improve the stability of supersonic plates.

Tailoring of composite cantilever beam for maximum stiffness and minimum weight

As the natural resources goes on decreasing now a days and to meet the needs of natural resources conservation, energy economy most of the manufacturers and their sub contractors are attempting to reduce the weight of the members in recent years. In this approach they are searching for low cost, high strength to weight ratio materials. Substituting composite structures for conventional metallic structures has many advantages because of higher specific stiffness and strength of composite materials. Composite materials have the major advantage of high strength to weight ratio with continuously decreasing travel of cost in addition to other advantages like excellent corrosive resistance, superior torsional buckling and fatigue strength and high specific strain energy storage capacity. The present work aims at the suitability of composite materials usage, by the identification of optimal fiber orientation stacking sequence and tailoring for laminate thickness/width for maximum stiffness and minimum weight design of laminated composite beam. The structural response is evaluated from conventional metallic structure with optimization techniques for maximizing stiffness and minimum weight. These metallic optimum values are extended initially to composite beam to maintain strength with the developed of optimization algorithm. Later with topology optimization and by tailoring cross-sections algorithm of the beam is evaluated with optimal fiber orientations and stacking sequence to maintain strength as in additional advantage of less weight for composites. Tailoring is done based on gradual decrement in cross-section over the length in both thickness and width direction. Numerical results are presented for cantilever beam with different geometries showing the maximizing stiffness and with minimum weight. The results indicate that the devised strategy is well suited for finding optimal fiber orientations and laminate thickness/width in the tailoring design of slender laminated composite structure.