Articoli di riviste: "Variable and anisotropic composites"

1

Robinson, D. N., e W. K. Binienda. "A Representation of Anisotropic Creep Damage in Fiber Reinforced Composites". Journal of Applied Mechanics 72, n. 4 (28 ottobre 2004): 484–92. http://dx.doi.org/10.1115/1.1875512.

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A creep damage model is presented that allows for anisotropic distributions of damage in composite materials. An earlier model by the writers allowed for anisotropic damage growth rate but, based on a scalar state variable, failed to account for anisotropic distributions of damage. A vectorial state variable is introduced that allows a representation of anisotropic damage distribution. As in earlier work, a fundamental assumption is that the principally damaging stress components are tensile traction and longitudinal shear at the fiber/matrix interface. Application of the creep damage model is made to calculations involving homogenously stressed composite elements under transverse tensile and longitudinal shear stress and to cross plied thin-walled tubes under tension/torsion. Although the emphasis is phenomenological, with focus on a mathematical structure for representing anisotropic distributions of damage, a meaningful creep damage model must rest on fundamental material science and microstructural examination. Verification experiments involving tension/torsion testing of thin-walled composite tubes together with detailed microstructural examination are discussed and outlined.

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Chang, Yan Jun, Ke Shi Zhang, Gui Qiong Jiao e Jian Yun Chen. "Application and Analysis of Plane Woven C/SiC Composites Based on Continuum Damage Mechanics". Advanced Materials Research 490-495 (marzo 2012): 3916–19. http://dx.doi.org/10.4028/www.scientific.net/amr.490-495.3916.

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The aim of this article was to propose a macroscopic damage model, which describes the nonlinear behavior observed on woven C/SiC ceramic matrix composites. The model was built within a thermodynamic framework with internal variables. The anisotropic damage evolution processes of the material were described by nonlinear damage isotropic and kinematic hardening functions in this model. The anisotropic damage and damage coupling were considered with a damage yield function including anisotropic coefficients. Using the principle of energy equivalence, the damage variables were defined by the unloading modulus and initial modulus. The damage variable and the irrecoverable strain induced by micro-crack propagation were deduced by thermodynamics. The constants of constitutive model were identified and the damage evolution processes under tensile and shear loading. Uniaxial tension and shear tests had been used to valid the constitutive model to C/SiC composites.

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3

Lu, C. H. "Bending of Anisotropic Sandwich Beams with Variable Thickness". Journal of Thermoplastic Composite Materials 7, n. 4 (ottobre 1994): 364–74. http://dx.doi.org/10.1177/089270579400700406.

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4

Mir, Hicham, Mario Fafard, Benoı^t Bissonnette e Marie-Laure Dano. "Damage Modeling in Random Short Glass Fiber Reinforced Composites Including Permanent Strain and Unilateral Effect". Journal of Applied Mechanics 72, n. 2 (1 marzo 2005): 249–58. http://dx.doi.org/10.1115/1.1839593.

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This paper presents the development of a theoretical damage mechanics model applicable to random short glass fiber reinforced composites. This model is based on a macroscopic approach using internal variables together with a thermodynamic potential expressed in the stress space. Induced anisotropic damage, nonsymmetric tensile/compressive behavior (unilateral effect) and residual effects (permanent strain) are taken into account. The anisotropic damage is represented with second-order tensorial internal variables D. The unilateral effect due to microcrack closure in compression is introduced by generalizing the hypothesis of the complementary elastic energy equivalence. In the case of the permanent strain, a new term related to frozen energy, which is a function of the damage variable, the stress tensor, and some materials constants to be identified, is added to the basic thermodynamic potential. Using laboratory test results, parameter identification has been performed to illustrate the applicability of the proposed model.

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Bittrich, Lars, Axel Spickenheuer, José Humberto S. Almeida, Sascha Müller, Lothar Kroll e Gert Heinrich. "Optimizing Variable-Axial Fiber-Reinforced Composite Laminates: The Direct Fiber Path Optimization Concept". Mathematical Problems in Engineering 2019 (19 febbraio 2019): 1–11. http://dx.doi.org/10.1155/2019/8260563.

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The concept of aligning reinforcing fibers in arbitrary directions offers a new perception of exploiting the anisotropic characteristic of the carbon fiber-reinforced polymer (CFRP) composites. Complementary to the design concept of multiaxial composites, a laminate reinforced with curvilinear fibers is called variable-axial (also known as variable stiffness and variable angle tow). The Tailored Fiber Placement (TFP) technology is well capable of manufacturing textile preforming with a variable-axial fiber design by using adapted embroidery machines. This work introduces a novel concept for simulation and optimization of curvilinear fiber-reinforced composites, where the novelty relies on the local optimization of both fiber angle and intrinsic thickness build-up concomitantly. This framework is called Direct Fiber Path Optimization (DFPO). Besides the description of DFPO, its capabilities are exemplified by optimizing a CFRP open-hole tensile specimen. Key results show a clear improvement compared to the current often used approach of applying principal stress trajectories for a variable-axial reinforcement pattern.

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Kawai, Masamichi, H. Kamioka, Jian Qi Zhang e Tetsuya Matsuda. "Off-Axis Creep Recovery of Unidirectional Carbon/Epoxy Composites at High Temperature". Key Engineering Materials 334-335 (marzo 2007): 65–68. http://dx.doi.org/10.4028/www.scientific.net/kem.334-335.65.

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Off-axis creep recovery behavior after complete unloading during creep at a constant stress is examined for a unidirectional T800H/3631 carbon/epoxy composite laminate at high temperature. Creep and creep recovery tests are performed on plain coupon specimens with four kinds of fiber orientations: 10, 30, 45 and 90°. It is observed that the creep strain appeared at a high stress does not completely recover after full removal of the creep stress, indicating that an irrecoverable creep strain has developed under the prior constant stress loading. Variable stress creep simulations are attempted using the modified kinematic hardening model for homogenized anisotropic inelastic composites in which an accelerated change in kinematic hardening over a certain range of viscoplastic strain is considered. Comparison with experimental results demonstrates that the proposed model can adequately describe the off-axis creep and creep recovery behaviors of the unidirectional composite system under constant and variable stress conditions.

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Almeida, José Humberto S., Lars Bittrich, Tsuyoshi Nomura e Axel Spickenheuer. "Cross-section optimization of topologically-optimized variable-axial anisotropic composite structures". Composite Structures 225 (ottobre 2019): 111150. http://dx.doi.org/10.1016/j.compstruct.2019.111150.

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Shafei, Erfan, Shirko Faroughi e Timon Rabczuk. "Multi-patch NURBS formulation for anisotropic variable angle tow composite plates". Composite Structures 241 (giugno 2020): 111964. http://dx.doi.org/10.1016/j.compstruct.2020.111964.

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9

Kakade, Ramakant S., Dr Ajay Chavan e Prof Mayuri S. Mhaske. "Analysis of Epoxy Fiber Composite Clamp with Variable Slotted Holes for Electric Overhead Crane Mounting". International Journal of Innovative Research in Advanced Engineering 10, n. 10 (10 dicembre 2023): 722–26. http://dx.doi.org/10.26562/ijirae.2023.v1010.02.

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Composite materials offer an excellent solution for structural applications requiring a high strength-to-weight ratio and stiffness-to-weight ratio. This is particularly beneficial in weight-sensitive structures like aircraft and spacecraft, where the cost-effectiveness of composite materials becomes evident. The exploration of composite materials encompasses various aspects, such as manufacturing processes, anisotropy, the elasticity strength of anisotropic materials, and micromechanics. This study focuses on the investigation of a novel glass epoxy composite material as a substitute for expensive, heavy, and corroding metals in applications involving tensile loadings. The objective is to experimentally analyze and employ finite element methods to understand the mechanical behavior of composite components, specifically those featuring slotted holes. Furthermore, the study aims to validate these findings using the finite element analysis (FEA) method.

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Kurkin, Evgenii, Oscar Ulises Espinosa Barcenas, Evgenii Kishov e Oleg Lukyanov. "Topology Optimization and Efficiency Evaluation of Short-Fiber-Reinforced Composite Structures Considering Anisotropy". Computation 12, n. 2 (12 febbraio 2024): 35. http://dx.doi.org/10.3390/computation12020035.

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The current study aims to develop a methodology for obtaining topology-optimal structures made of short fiber-reinforced polymers. Each iteration of topology optimization involves two consecutive steps: the first is a simulation of the injection molding process for obtaining the fiber orientation tensor, and the second is a structural analysis with anisotropic material properties. Accounting for the molding process during the internal iterations of topology optimization makes it possible to enhance the weight efficiency of structures—a crucial aspect, especially in aerospace. Anisotropy is considered through the fiber orientation tensor, which is modeled by solving the plastic molding equations for non-Newtonian fluids and then introduced as a variable in the stiffness matrix during the structural analysis. Structural analysis using a linear anisotropic material model was employed within the topology optimization. For verification, a non-linear elasto-plastic material model was used based on an exponential-and-linear hardening law. The evaluation of weight efficiency in structures composed of short-reinforced composite materials using a dimensionless criterion is addressed. Experimental verification was performed to confirm the validity of the developed methodology. The evidence illustrates that considering anisotropy leads to stiffer structures, and structural elements should be oriented in the direction of maximal stiffness. The load-carrying factor is expressed in terms of failure criteria. The presented multidisciplinary methodology can be used to improve the quality of the design of structures made of short fiber-reinforced composites (SFRC), where high stiffness, high strength, and minimum mass are the primary required structural characteristics.

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Kölbl, Michael, Maria Sakovsky e Paolo Ermanni. "A highly anisotropic morphing skin unit cell with variable stiffness ligaments". Composite Structures 254 (dicembre 2020): 112801. http://dx.doi.org/10.1016/j.compstruct.2020.112801.

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12

Mitoseriu, Liliana, Laurentiu Stoleriu, Alexandru Stancu, Carmen Galassi e Vincenzo Buscaglia. "First order reversal curves diagrams for describing ferroelectric switching characteristics". Processing and Application of Ceramics 3, n. 1-2 (2009): 3–7. http://dx.doi.org/10.2298/pac0902003m.

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First Order Reversal Curves (FORC) are polarization-field dependences described between saturation field Esat and a variable reversal field E,?(-Esat, Esat). The FORC diagrams were proposed to describe some characteristics of the switching process in ferroelectrics. The approach is related to the Preisach model which considers the distribution of the elementary switchable units over their coercive and bias fields. The influence of the anisotropic porosity in Pb(Zr,Ti)O3 bulk ceramics on the FORC distributions demonstrated the existence of a positive/negative bias as a result of the confinement induced by anisotropy. The reducing of grain size in Ba(Zr,Ti)O3 ceramics causes an increase of the ratio of the reversible/irreversible components of the polarization on the FORC distribution indicating the tendency of system towards the superparaelectric state. The FORC method demonstrates to provide a kind of 'fingerprinting' of various types of switching characteristics in ferroic systems. .

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13

Hwu, C. "Stroh-Like Complex Variable Formalism for the Bending Theory of Anisotropic Plates". Journal of Applied Mechanics 70, n. 5 (1 settembre 2003): 696–707. http://dx.doi.org/10.1115/1.1600474.

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Based upon the knowledge of the Stroh formalism and the Lekhnitskii formalism for two-dimensional anisotropic elasticity as well as the complex variable formalism developed by Lekhnitskii for plate bending problems, in this paper a Stroh-like formalism for the bending theory of anisotropic plates is established. The key feature that makes the Stroh formalism more attractive than the Lekhnitskii formalism is that the former possesses the eigenrelation that relates the eigenmodes of stress functions and displacements to the material properties. To retain this special feature, the associated eigenrelation and orthogonality relation have also been obtained for the present formalism. By intentional rearrangement, this new formalism and its associated relations look almost the same as those for the two-dimensional problems. Therefore, almost all the techniques developed for the two-dimensional problems can now be applied to the plate bending problems. Thus, many unsolved plate bending problems can now be solved if their corresponding two-dimensional problems have been solved successfully. To illustrate this benefit, two simple examples are shown in this paper. They are anisotropic plates containing elliptic holes or inclusions subjected to out-of-plane bending moments. The results are simple, exact and general. Note that the anisotropic plates treated in this paper consider only the homogeneous anisotropic plates. If a composite laminate is considered, it should be a symmetric laminate to avoid the coupling between stretching and bending behaviors.

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14

Kawai, Masamichi, e Jian Qi Zhang. "A Modified Kinematic-Hardening Viscoplasticity Model for Off-Axis Creep Behavior of Unidirectional CFRPs at High Temperature". Key Engineering Materials 340-341 (giugno 2007): 161–66. http://dx.doi.org/10.4028/www.scientific.net/kem.340-341.161.

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A macromechanics constitutive model to describe the anisotropic creep behavior of unidirectional composites under off-axis loading conditions is developed with a particular emphasis on accurate prediction of temporal creep softening due to stress variation. A viscoplasticity model that takes account of a combined isotropic and kinematic hardening is adopted as a base for this formulation, and the evolution equation of the kinematic hardening variable is elaborated to enhance the accuracy of prediction of the transient creep softening due to stress variation. Validity of the modified kinematic-hardening viscoplasticity model is evaluated by comparing with the experimental results on unidirectional T800H/3631 carbon/epoxy composites. It is demonstrated that the proposed model can adequately describe the off-axis creep behavior of the unidirectional CFRP laminate under constant and variable stress conditions.

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15

Chang, Yan Jun, Ke Shi Zhang, Gui Qiong Jiao e Jian Yun Chen. "Damage Theoretical Analysis of 2.5D C/SiC Composites under Tensile and Shear Loading". Advanced Materials Research 150-151 (ottobre 2010): 330–33. http://dx.doi.org/10.4028/www.scientific.net/amr.150-151.330.

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An anisotropic damage constitutive model is developed to describe the damage behavior of C/SiC composites. Different kinematic and isotropic hardening functions were employed in damage yield function to describe accurately the damage nonlinear hardening. The damage variable is defined by the principle of energy equivalence. The degradation of stiffness and the unrecoverable deformation induced by micro-crack propagation were considered in this model. The constants of constitutive model are identified and the damage evolution processes under tensile and shear loading. Uniaxial tension and shear tests have been used to valid the constitutive model to C/SiC composites.

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16

Steele, Charles R., e Yoon Young Kim. "Modified Mixed Variational Principle and the State-Vector Equation for Elastic Bodies and Shells of Revolution". Journal of Applied Mechanics 59, n. 3 (1 settembre 1992): 587–95. http://dx.doi.org/10.1115/1.2893764.

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A modified mixed variational principle is established for a class of problems with one spatial variable as the independent variable. The specific applications are on the three-dimensional deformation of elastic bodies and the nonsymmetric deformation of shells of revolution. The possibly novel feature is the elimination in the variational formulation of the stress components which cannot be prescribed on the boundaries. The result is a form exactly analogous to classical mechanics of a dynamic system, with the equations of state exactly in the form of the canonical equations of Hamilton. With the present approach, the correct scale factors of the field variables to make the system self-adjoint are readily identified, and anisotropic materials including composites can be handled effectively. The analysis for shells of revolution is given with and without the transverse shear deformation considered.

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17

Xiong, Chun-Bao, Li-Na Yu e Yan-Bo Niu. "Effect of Variable Thermal Conductivity on the Generalized Thermoelasticity Problems in a Fiber-Reinforced Anisotropic Half-Space". Advances in Materials Science and Engineering 2019 (3 settembre 2019): 1–9. http://dx.doi.org/10.1155/2019/8625371.

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Fiber-reinforced materials have widespread applications, which prompt the study of the effect of fiber reinforcement. Research studies have indicated that thermal conductivity cannot be considered as a constant, which is closely related to temperature change. Based on those studies, we investigate the fiber-reinforced generalized thermoelasticity problem under thermal stress, with the consideration of the effect of temperature-dependent variable thermal conductivity. The problem is assessed according to the L-S theory. A fiber-reinforced anisotropic half-space is selected as the research model, and a region of its surface is subjected to a transient thermal shock. The time-domain finite element method is applied to analyze the nonlinear problem and derives the governing equations. The nondimensional displacement, stress, and temperature of the material are obtained and illustrated graphically. The numerical results reveal that the variable conductivity significantly influences the distribution of the field quantities under the fiber-reinforced effect. And also, the boundary point of thermal shock is the most affected. The obtained results in this paper can be applied to design the fiber-reinforced anisotropic composites under thermal load to satisfy some particular engineering requirements.

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Wu, Kuang-Chong, e Yu-Tsung Chiu. "Antiplane Shear Interface Cracks in Anisotropic Bimaterials". Journal of Applied Mechanics 58, n. 2 (1 giugno 1991): 399–403. http://dx.doi.org/10.1115/1.2897199.

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An analysis of antiplane shear interface cracks in a finite anisotropic composite body is presented. The analysis is done by a new complex-variable integral equation formulation based on the solutions of a dislocation and body force in an infinite composite body. Numerical results of the stress intensity factors are presented for the composite bodies with finite rectangular cross-sections under uniform shear. The composite bodies are formed by bonding an orthotropic material to an isotropic material. The numerical results show that there exists a lower bound for the stress intensity factor for a fixed crack-length-to-height ratio and that the lower bound is attained in the case of isotropic bimaterial.

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Orii, Yuta, Masaki Kobayashi, Yuki Nagai, Kohei Atsumi, Daichi Tazaki, Satoshi Ehara e Takashiro Akitsu. "Anisotropic strain and Jahn-Teller effect of chiral complexes and metal oxides". Acta Crystallographica Section A Foundations and Advances 70, a1 (5 agosto 2014): C179. http://dx.doi.org/10.1107/s2053273314098209.

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For about a decade, we have systematically investigated thermally-accessible lattice strain and local pseudo Jahn-Teller distortion of [CuL2]3[M(CN)6]2·4H2O (L = (1R, 2R)-cyclohexanediamine; M = Cr, Co, and Fe). In mononuclear Cu(II) complexes, (pseudo) Jahn-Teller effect plays an important role in flexible distortion of crystal structures especially Cu(II) coordination environment. Beside Jahn-Teller distortion, we have dealt with some factors for example, metal substitution as bimetallic assemblies, chirality of ligands, and H/D isotope effect to vary intermolecular interaction and crystal packing. According to the course work using variable temperature PXRD, we have found that anisotropy of crystal strain distortion did not corporate with Jahn-Teller distortion around local coordination environment because of the discrepancy of the crystallographic axes and molecular alignment. In order to elucidate the anisotropic control of lattice strain and Jahn-Teller distortion closely, we have employed transition metal oxide with orthogonal or layered structures to prepare composite materials with the chiral metal complexes for discussion of thermally-accessible PXRD changes and IR shift due to adsorption. At first, we have employed chiral one-dimensional zig-zag Cu-Cr bimetallic assemblies and their oxides prepared by burining. Based on variable temperature XRD patterns, a linear correlation (lnK = a/T + b) of K (=d(T)-d(0)/d(T)) values, where d(T) and d(0) are spacing of lattice plane (d = nλ/(2sinθ)) at T K and 0 K (extrapolated), respectively, and its deviation from ideal correlation indicates degree of anisotropic lattice distortion of the composite materials. For example, we could observe LiMnO2, typical material of lithium ion battery, was enhanced anisotropic lattice strain along the b axis or the (011) plane added by [CuL2(H2O)2](NO3)2 complexes. Which may prevent from breaking down regular crystal structures during charge-discharge of secondary battery.

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Chen, Yijin, Jian Sun, Yanju Liu e Jinsong Leng. "Experiment and analysis of fluidic flexible matrix composite (F2MC) tube". Journal of Intelligent Material Systems and Structures 23, n. 3 (11 settembre 2011): 279–90. http://dx.doi.org/10.1177/1045389x11420591.

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In this research, a fluidic flexible matrix composites (F2MC) tube composed of flexible matrix composite (FMC) and inner liner is investigated. Significant changes in effective axial elastic modulus could be achieved through controlling the interior fluid. Based on classical laminated-plate theory and anisotropic elasticity, a three-dimensional analytical method is proposed to characterize the axial mechanical behavior of the F2MC tube. In comparison with the experiment result, the analysis is deemed to possess satisfying accuracy in the effective axial elastic modulus prediction of the F2MC tube. In addition, the effective axial elastic modulus ratio is discussed under different material and geometry parameters of the tube. The analysis result shows that the modulus ratio can reach up to 120 by refining the material and geometry parameters. Therefore, the investigated F2MC tube could serve as potential candidate for the morphing skin applications with variable stiffness.

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Chao, C. K., e R. C. Chang. "Thermoelastic Problem of Dissimilar Anisotropic Solids With a Rigid Line Inclusion". Journal of Applied Mechanics 61, n. 4 (1 dicembre 1994): 978–80. http://dx.doi.org/10.1115/1.2901590.

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A general solution to the thermoelastic problem of an interface rigid line inclusion between anisotropic dissimilar media is presented. The complex variable representation of plane elastic problem developed by Lekhnitskii is extended into anisotropic thermoelasticity, and a special technique of analytical continuation is introduced to deal with the dissimilar media problem. It is indicated that singularities of the thermal stresses induced by a rigid line inclusion are similar to the case of a slit crack. A numerical example for zirconia bonded to titanium composite under remote heat flux is also examined.

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Groh, R. M. J., e P. M. Weaver. "Deleterious localized stress fields: the effects of boundaries and stiffness tailoring in anisotropic laminated plates". Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 472, n. 2194 (ottobre 2016): 20160391. http://dx.doi.org/10.1098/rspa.2016.0391.

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The safe design of primary load-bearing structures requires accurate prediction of stresses, especially in the vicinity of geometric discontinuities where deleterious three-dimensional stress fields can be induced. Even for thin-walled structures significant through-thickness stresses arise at edges and boundaries, and this is especially precarious for laminates of advanced fibre-reinforced composites because through-thickness stresses are the predominant drivers in delamination failure. Here, we use a higher-order equivalent single-layer model derived from the Hellinger–Reissner mixed variational principle to examine boundary layer effects in laminated plates comprising constant-stiffness and variable-stiffness laminae and deforming statically in cylindrical bending. The results show that zigzag deformations, which arise due to layerwise differences in the transverse shear moduli, drive boundary layers towards clamped edges and are therefore critically important in quantifying localized stress gradients. The relative significance of the boundary layer scales with the degree of layerwise anisotropy and the thickness to characteristic length ratio. Finally, we demonstrate that the phenomenon of alternating positive and negative transverse shearing deformation through the thickness of composite laminates, previously only observed at clamped boundaries, can also occur at other locations as a result of smoothly varying the material properties over the in-plane dimensions of the laminate.

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HILTON, HARRY H. "ON THE INADMISSIBILITY OF SEPARATION OF VARIABLES SOLUTIONS IN LINEAR ANISOTROPIC VISCOELASTICITY". Mechanics of Composite Materials and Structures 3, n. 2 (giugno 1996): 97–100. http://dx.doi.org/10.1080/10759419608945857.

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Hilton, Harry H. "On the inadmissibility of separation of variables solutions in linear anisotropic viscoelasticity". Mechanics of Composite Materials and Structures 3, n. 2 (giugno 1996): 97–100. http://dx.doi.org/10.1002/(sici)1234-986x(199606)3:2<97::aid-mcm34>3.3.co;2-k.

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Hao, Ying, Wei He e Yanke Shi. "Differential Equations of Motion for Naturally Curved and Twisted Composite Space Beams". Shock and Vibration 2018 (2018): 1–12. http://dx.doi.org/10.1155/2018/5015807.

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The differential equations of motion for naturally curved and twisted elastic space beams made of anisotropic materials with noncircular cross sections, being a coupled system consisting of 14 second-order partial differential equations with variable coefficients, are derived theoretically. The warping deformation of beam’s cross section, as a new design factor, is incorporated into the differential equations in addition to the anisotropy of material, the curvatures of the rod axis, the initial twist of the cross section, the rotary inertia, and the shear and axial deformations. Numerical examples show that the effect of warping deformation on the natural frequencies of the beam is significant under certain geometric and boundary conditions. This study focuses on improving and consummating the traditional theories to build a general curve beam theory, thereby providing new scientific research reference and design principle for curve beam designers.

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Alghanmi, Rabab A. "Nonlocal Strain Gradient Theory for the Bending of Functionally Graded Porous Nanoplates". Materials 15, n. 23 (2 dicembre 2022): 8601. http://dx.doi.org/10.3390/ma15238601.

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Many investigators have become interested in nanostructures due to their outstanding mechanical, chemical, and electrical properties. Two-dimensional nanoplates with higher mechanical properties compared with traditional structural applications are a common structure of nanosystems. Nanoplates have a wide range of uses in various sectors due to their unique properties. This paper focused on the static analysis of functionally graded (FG) nanoplates with porosities. The nonlocal strain gradient theory is combined with four-variable shear deformation theory to model the nanoplate. The proposed model captures both nonlocal and strain gradient impacts on FG nanoplate structures by incorporating the nonlocal and strain gradient factors into the FG plate’s elastic constants. Two different templates of porosity distributions are taken into account. The FG porous nanoplate solutions are compared with previously published ones. The impact of nonlocal and strain gradient parameters, side-to-thickness ratio, aspect ratio, and porosity parameter, are analyzed in detail numerically. This paper presents benchmark solutions for the bending analysis of FG porous nanoplates. Moreover, the current combination of the nonlocal strain gradient theory and the four-variable shear deformation theory can be adapted for various nanostructured materials such as anisotropic, laminated composites, FG carbon nanotube reinforced composites, and so on.

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Man'kovskii, V. A. "Applied theories of plasticity of porous, ?Variable-strength,? and anisotropic media 1. Initial assumptions". Mechanics of Composite Materials 21, n. 6 (1986): 663–68. http://dx.doi.org/10.1007/bf00605926.

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Nagy, Endre, e Márta Vitai. "Analysis of Mass Transport through Anisotropic, Catalytic/Bio-Catalytic Membrane Reactors". Catalysts 9, n. 4 (13 aprile 2019): 358. http://dx.doi.org/10.3390/catal9040358.

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This paper investigated the steady-state mass transport process through anisotropic, composite membrane layers with variable mass transport coefficients, such as the diffusion coefficient, convective velocity, or chemical/biochemical reaction rate constant. The transfer processes can be a solution-diffusion model or diffusive plus convective process. In the theoretical part, the concentration distribution as well as the inlet and outlet mass transfer rates’ expressions are defined for physical transport processes with variable diffusion or solubility coefficients and then that for transport processes accompanied by first- and zero-order reactions, in the presence of diffusive and convective flow, with constant and variable parameters. The variation of the transport parameters as a function of the local coordinate was defined by linear equations. It was shown that the increasing diffusion coefficient or convective flow induces much lower concentrations across the membrane layer than transport processes, with their decreasing values a function of the space coordinate. Accordingly, this can strongly affect the effect of the concentration dependent chemical/biochemical reaction. The inlet mass transfer rate can also be mostly higher when the transport parameter decreases across the anisotropic membrane layer.

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Grönquist, Philippe, Prijanthy Panchadcharam, Dylan Wood, Achim Menges, Markus Rüggeberg e Falk K. Wittel. "Computational analysis of hygromorphic self-shaping wood gridshell structures". Royal Society Open Science 7, n. 7 (luglio 2020): 192210. http://dx.doi.org/10.1098/rsos.192210.

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Bi-layered composites capable of self-shaping are of increasing relevance to science and engineering. They can be made out of anisotropic materials that are responsive to changes in a state variable, e.g. wood, which swells and shrinks by changes in moisture. When extensive bending is desired, such bilayers are usually designed as cross-ply structures. However, the nature of cross-ply laminates tends to prevent changes of the Gaussian curvature so that a plate-like geometry of the composite will be partly restricted from shaping. Therefore, an effective approach for maximizing bending is to keep the composite in a narrow strip configuration so that Gaussian curvature can remain constant during shaping. This represents a fundamental limitation for many applications where self-shaped double-curved structures could be beneficial, e.g. in timber architecture. In this study, we propose to achieve double-curvature by gridshell configurations of narrow self-shaping wood bilayer strips. Using numerical mechanical simulations, we investigate a parametric phase-space of shaping. Our results show that double curvature can be achieved and that the change in Gaussian curvature is dependent on the system’s geometry. Furthermore, we discuss a novel architectural application potential in the form of self-erecting timber gridshells.

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Duc, Nguyen Dinh, e Nguyen Van Thuong. "Adhesive contact between two-dimensional anisotropic elastic bodies". Vietnam Journal of Mechanics 45, n. 4 (28 dicembre 2023): 318–33. http://dx.doi.org/10.15625/0866-7136/19700.

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Adhesion plays a vital role in the design of smart and intelligent high-tech devices such as modern optical, microelectromechanical, and biomedical systems. However, in the literature, adhesive contact is mostly considered for contact of rigid substrates and transversely isotropic and isotropic elastic materials. The composite materials are increasingly used in the mart and intelligent high-tech devices. Since the composite materials are generally anisotropic and contact bodies are all deformable, it is more practical to consider the adhesive contact of two anisotropic elastic materials. In this paper, an adhesive contact model of anisotropic elastic bodies is established, and the closed-form solutions for two-dimensional adhesive contact of two anisotropic elastic bodies are derived. The full-field solutions and the relation for the contact region and applied force are developed using the Stroh complex variable formalism, the analytical continuation method, and concepts of the JKR adhesive model. We will show that the frictionless contact of two anisotropic elastic materials is just a special case of the present contact problem, and its solutions can be obtained by setting the work of adhesion equal to zero. In addition, we also show that our present solutions are valid for the problems of indentation by a rigid punch on an elastic half-space through a proper placement of the contact radius and the corresponding material constant. Numerical results are provided to demonstrate the accuracy, applicability, and versatility of the developed solutions.

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31

NARESH, HAZARI, e Dr Chinmaya Padhy. "Effect of Turning Parameter and Fiber Pullout on Machinability of Unidirectional EGFRP under Cryogenic Condition". International Journal of Automotive and Mechanical Engineering 20, n. 2 (30 giugno 2023): 10398–410. http://dx.doi.org/10.15282/ijame.20.2.2023.06.0804.

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The non-homogeneous and anisotropic nature of composites poses challenges during machining, requiring the use of specialized cutting tools. GFRP materials were selected for their excellent elasticity, corrosion resistance, and high strength, making them ideal for applications in the aerospace and automotive industries. In this work, the surface quality of UD-GFRP composite bars during CNC machining in diverse machining conditions (dry, wet, and cryogenic) was investigated while considering the fiber-pullout issue. The UD-EGFRP composite materials have been machined with a polycrystalline diamond tool. The Taguchi-L9 orthogonal-array technique is used to investigate and further analysis. Three independent-variables feed rate, rotational speed or cutting speed, and depth of cut have been taken into account for their optimal design to get better machinability of EGFRP. This study also investigates the delamination criterion in composites and establishes the correlation between its input parameters and output responses. The findings revealed that cryogenic machining led to a notable improvement of 25.21% in surface roughness compared to the other lubrication methods. Also, the reduction from 84 µm to 34 µm in fiber-pullout signifies that cryogenic cooling effectively mitigated the occurrence of fiber-pullout.

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32

Rose, J. L., A. Pilarski, K. Balasubramaniam, A. Tverdokhlebov e J. Ditri. "Ultrasonic Wave Considerations for the Development of an NDE Feature Matrix for Anisotropic Media". Journal of Engineering Materials and Technology 111, n. 3 (1 luglio 1989): 255–62. http://dx.doi.org/10.1115/1.3226464.

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Abstract (sommario):

The problem of ultrasonic surface and bulk wave propagation in an anisotropic media and/or a composite material is addressed so that applications in Nondestructive Evaluation can be considered, emphasis in this paper being placed on bulk wave propagation. Global material property determination is considered in an inverse wave velocity computation of stiffness coefficients based on principles of anisotropic elasticity. A one-sided inspection technique based on practical considerations of a field environment is developed. The concept of a feature matrix, based on the stiffness coefficients, is then introduced as a means of both material characterization and defect analysis in composite materials. A brief discussion on a test protocol and an interpretation of the elements in the feature matrix from an NDE point of view is also presented. The conclusions of a previous theoretical investigation of wave propagation in anisotropic media are considered from an experimental point of view by way of the bulk wave technique. A result of fundamental value is that the actual propagation of quasilongitudinal waves, generated by a standard broad band pulsed transducer, is indeed well matched with the theoretical approximation obtained earlier. This approximation was based on the generalized retarded potential principle with variable energy velocity of the quasilongitudinal mode in an anisotropic medium as the substitute for the constant longitudinal velocity used in the retarded potential scheme for an isotropic medium.

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Borowski, Andreas, Christian Vogel, Thomas Behnisch, Vinzenz Geske, Maik Gude e Niels Modler. "Additive Manufacturing-Based In Situ Consolidation of Continuous Carbon Fibre-Reinforced Polycarbonate". Materials 14, n. 9 (9 maggio 2021): 2450. http://dx.doi.org/10.3390/ma14092450.

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Abstract (sommario):

Continuous carbon fibre-reinforced thermoplastic composites have convincing anisotropic properties, which can be used to strengthen structural components in a local, variable and efficient way. In this study, an additive manufacturing (AM) process is introduced to fabricate in situ consolidated continuous fibre-reinforced polycarbonate. Specimens with three different nozzle temperatures were in situ consolidated and tested in a three-point bending test. Computed tomography (CT) is used for a detailed analysis of the local material structure and resulting material porosity, thus the results can be put into context with process parameters. In addition, a highly curved test structure was fabricated that demonstrates the limits of the process and dependent fibre strand folding behaviours. These experimental investigations present the potential and the challenges of additive manufacturing-based in situ consolidated continuous fibre-reinforced polycarbonate.

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Tornabene, Francesco, Matteo Viscoti, Rossana Dimitri e Junuthula N. Reddy. "Higher order theories for the vibration study of doubly-curved anisotropic shells with a variable thickness and isogeometric mapped geometry". Composite Structures 267 (luglio 2021): 113829. http://dx.doi.org/10.1016/j.compstruct.2021.113829.

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35

Bhandari, Binayak, Phyo Thu Maung e Gangadhara B. Prusty. "Novel Response Surface Technique for Composite Structure Localization Using Variable Acoustic Emission Velocity". Sensors 24, n. 11 (27 maggio 2024): 3450. http://dx.doi.org/10.3390/s24113450.

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Abstract (sommario):

The time difference of arrival (TDOA) method has traditionally proven effective for locating acoustic emission (AE) sources and detecting structural defects. Nevertheless, its applicability is constrained when applied to anisotropic materials, particularly in the context of fiber-reinforced composite structures. In response, this paper introduces a novel COmposite LOcalization using Response Surface (COLORS) algorithm based on a two-step approach for precise AE source localization suitable for laminated composite structures. Leveraging a response surface developed from critical parameters, including AE velocity profiles, attenuation rates, distances, and orientations, the proposed method offers precise AE source predictions. The incorporation of updated velocity data into the algorithm yields superior localization accuracy compared to the conventional TDOA approach relying on the theoretical AE propagation velocity. The mean absolute error (MAE) for COLORS and TDOA were found to be 6.97 mm and 8.69 mm, respectively. Similarly, the root mean square error (RMSE) for COLORS and TODA methods were found to be 9.24 mm and 12.06 mm, respectively, indicating better performance of the COLORS algorithm in the context of source location accuracy. The finding underscores the significance of AE signal attenuation in minimizing AE wave velocity discrepancies and enhancing AE localization precision. The outcome of this investigation represents a substantial advancement in AE localization within laminated composite structures, holding potential implications for improved damage detection and structural health monitoring of composite structures.

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Paul, Saurav, Bimal Bhushan Chakraborty, Kuheli Deb e Sudip Choudhury. "Synthesis of mesogen-nanoparticle composites by doping 4-decyloxybenzoic acid with substrate-functionalized ZnO nanoparticle". Communications in Science and Technology 8, n. 1 (8 luglio 2023): 38–42. http://dx.doi.org/10.21924/cst.8.1.2023.1125.

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Abstract (sommario):

Nanomaterials and Mesogenic materials are two important pillars of today’s science and technology, in the fields of both material and biological applications. Mesogens or liquid crystals (LC) are self-aggregated anisotropic fluids with long range order, and the nature of self-aggregation largely controls their physical and material properties. Doping of nanomaterials over liquid crystalline matrix can provide valuable tools for development of materials with new or improved properties. In the present work 4-decyloxybenzoic acid is taken as the mesogenic matrix. It is observed that, composite prepared by doping of 4-decyloxybenzoic acid mesogen matrix by ZnO nanoparticle pre-functionalized with the same mesogen, caused a marked alteration in the mesogenic behavior. With 3% doping of matrix pre-functionalized ZnO NP on 4- decyloxy benzoic acid, we could achieve a shift of about 31ºC in the N-Iso transition temperature and, a decrease of >10ºC for the onset of liquid crystallinity by this method without quenching any of the mesophases exhibited by the pure mesogen. The synthesized materials have been characterized by variable temperature Polarised optical microscopy (POM), DSC, FTIR, XRD, EDX, and TEM This process may be considered for preparation other nanoparticle-mesogen composites as well. It was observed that, the effect of doping on the transition temperature and enthalpy of 4-Decyloxybenzoic Acid can be significantly enhanced by pre-functionalizing the dopant (ZnO NP) with the substrate molecules and then mixing this substrate functionalized ZnO nanoparticle with the bulk substrate.

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37

Patwardhan, J. S., e W. Roger Cannon. "Factors Influencing Anisotropic Sintering Shrinkage in Tape-Cast Alumina: Effect of Processing Variables". Journal of the American Ceramic Society 89, n. 10 (ottobre 2006): 3019–26. http://dx.doi.org/10.1111/j.1551-2916.2006.01169.x.

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38

Zhang, Xue Xia, Xiao Chao Cui, Wei Yang Yang e Wen Bin Zhao. "An Analytical Solution for Anisotropic Composite Plate of Crack under Bending and Twisting". Advanced Materials Research 197-198 (febbraio 2011): 1567–72. http://dx.doi.org/10.4028/www.scientific.net/amr.197-198.1567.

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Analysis of mechanical behaviors near crack tip for linear elastic anisotropic composite plate under bending loadings and twisting loadings was done. By introducing proper deflection function, the mechanical problem reduced to the boundary value problem of partial differential equation. The mixed mode stress intensity factor at the crack tip were presented under bending loadings and twisting loadings at infinity. By solving boundary value problem of partial differential equation and using a complex variable function method, the expressions for bending moments, strains and displacements near crack tip are derived. The obtained results are used to the theoretical research and experimental analysis of the fracture problems of composite plate.

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39

Kobelev, Vladimir. "Approximate static aeroelastic analysis of composite wings". Multidiscipline Modeling in Materials and Structures 15, n. 2 (21 febbraio 2019): 365–86. http://dx.doi.org/10.1108/mmms-02-2018-0019.

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PurposeThe purpose of this paper is to consider divergence of composite plate wings as well as slender wings with thin-walled cross-section of small-size airplanes. The main attention is paid to establishing of closed-form mathematical solutions for models of wings with coupling effects. Simplified solutions for calculating the divergence speed of wings with different geometry are established.Design/methodology/approachThe wings are modeled as anisotropic plate elements and thin-walled beams with closed cross-section. Two-dimensional plate-like models are applied to analysis and design problems for wings of large aspect ratio.FindingsAt first, the equations of elastic deformation for anisotropic slender, plate-like wing with the large aspect ratio are studied. The principal consideration is delivered to the coupled torsion-bending effects. The influence of anisotropic tailoring on the critical divergence speed of the wing is examined in closed form. At second, the method is extended to study the behavior of the large aspect ratio, anisotropic wing with box-like wings. The static equations of the wing with box-like profile are derived using the theory of anisotropic thin-walled beams with closed cross-section. The solutions for forward-swept wing with box-like profiles are given in analytical formulas. The formulas for critical divergence speed demonstrate the dependency upon cross-sectional shape characteristics and anisotropic properties of the wing.Research limitations/implicationsThe following simplifications are used: the simplified aerodynamic theory for the wings of large aspect ratio was applied; the static aeroelastic instability is considered (divergence); according to standard component methodology, only the component of wing was modeled, but not the whole aircraft; the simplified theories (plate-lime model for flat section or thin-walled beam of closed-section) were applied; and a single parameter that defines the rotation of a stack of single layers over the face of the wing.Practical implicationsThe simple, closed-form formulas for an estimation of critical static divergence are derived. The formulas are intended for use in designing of sport aircraft, gliders and small unmanned aircraft (drones). No complex analysis of airflow and advanced structural and aerodynamic models is necessary. The expression for chord length over the span of the wing allows for accounting a board class of wing shapes.Social implicationsThe derived theory facilitates the use of composite materials for popular small-size aircraft, and particularly, for drones and gliders.Originality/valueThe closed-form solutions for thin-walled beams in steady gas flow are delivered in closed form. The explicit formulas for slender wings with variable chord and stiffness along the wing span are derived.

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40

Idiart, Martín I., Noel Lahellec e Pierre Suquet. "Model reduction by mean-field homogenization in viscoelastic composites. I. Primal theory". Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 476, n. 2242 (ottobre 2020): 20200407. http://dx.doi.org/10.1098/rspa.2020.0407.

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A homogenization scheme for viscoelastic composites proposed by Lahellec & Suquet (2007 Int. J. Solids Struct. 44 , 507–529 ( doi:10.1016/j.ijsolstr.2006.04.038 )) is revisited. The scheme relies upon an incremental variational formulation providing the inelastic strain field at a given time step in terms of the inelastic strain field from the previous time step, along with a judicious use of Legendre transforms to approximate the relevant functional by an alternative functional depending on the inelastic strain fields only through their first and second moments over each constituent phase. As a result, the approximation generates a reduced description of the microscopic state of the composite in terms of a finite set of internal variables that incorporates information on the intraphase fluctuations of the inelastic strain and that can be evaluated by mean-field homogenization techniques. In this work we provide an alternative derivation of the scheme, relying on the Cauchy–Schwarz inequality rather than the Legendre transform, and in so doing we expose the mathematical structure of the resulting approximation and generalize the exposition to fully anisotropic material systems.

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Meißner, Sven, Jiri Kafka, Hannah Isermann, Susanna Labisch, Antonia Kesel, Oliver Eberhardt, Harald Kuolt et al. "Development and Evaluation of a Novel Method for Reinforcing Additively Manufactured Polymer Structures with Continuous Fiber Composites". Journal of Composites Science 8, n. 7 (14 luglio 2024): 272. http://dx.doi.org/10.3390/jcs8070272.

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Abstract (sommario):

Additively manufactured polymer structures often exhibit strong anisotropies due to their layered composition. Although existing methods in additive manufacturing (AM) for improving the mechanical properties are available, they usually do not eliminate the high degree of structural anisotropy. Existing methods for continuous fiber (cF) reinforcement in AM can significantly increase the mechanical properties in the strand direction, but often do not improve the interlaminar strength between the layers. In addition, it is mostly not possible to deposit cFs three-dimensionally and curved (variable–axial) and, thus, in a path that is suitable for the load case requirements. There is a need for AM methods and design approaches that enable cF reinforcements in a variable–axial way, independently of the AM mounting direction. Therefore, a novel two-stage method is proposed in which the process steps of AM and cF integration are decoupled from each other. This study presents the development and validation of the method. It was first investigated at the specimen level, where a significant improvement in the mechanical properties was achieved compared to unreinforced polymer structures. The Young’s modulus and tensile strength were increased by factors of 9.1 and 2.7, respectively. In addition, the design guidelines were derived based on sample structures, and the feasibility of the method was demonstrated on complex cantilevers.

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42

Eisenhauer, Charlotte M., e Klaus Drechsler. "Integration of excess material into a semi-finished product to form complex composite parts". Textile Research Journal 87, n. 19 (30 settembre 2016): 2420–31. http://dx.doi.org/10.1177/0040517516671119.

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Abstract (sommario):

With a view to minimizing production costs of carbon fiber-reinforced plastics (CFRP), a contoured, variable-axial reinforcing fabric, so-called “CoCo – contoured composites,” has been developed for complex, primary structural components,. Thereby, scrap in the production of lightweight high-performance components out of CFRP is reduced. Furthermore, components can be designed in an anisotropic way, thus lighter and adapted to the fiber properties. Moreover, production speed will be by far higher than that of conventional variable-axial textiles, like tailored fiber placement and fiber patch preforming. Furthermore, these textiles will show higher drapability than conventional production techniques, like tape-laying or standard textiles. The main focus of this paper is the investigation of draping mechanisms of variable-axial, tailored textiles and their feasibility. To reach high drapability of these semi-finished products, a new draping strategy has been developed. Reinforcing rovings are laid in meander way onto a carrier material holding excess material available for draping. For the textile “CoCo” new draping characteristics have been investigated, showing a kind of stretch forming of the carrier material and a straightening of the reinforcing fibers previously laid in meander. Due to this draping mechanism the material has the ability to form over very complex shapes without showing draping defects, like loops, gaps, or waviness. The calculation of the excess material and the draping mechanism are investigated on a complex form and proven by draping trials.

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Kehrer, Loredana, Jeffrey T. Wood e Thomas Böhlke. "Mean-field homogenization of thermoelastic material properties of a long fiber-reinforced thermoset and experimental investigation". Journal of Composite Materials 54, n. 25 (26 aprile 2020): 3777–99. http://dx.doi.org/10.1177/0021998320920695.

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Fiber-reinforced polymers contribute significantly to weight-reducing components for various industrial applications. A discontinuous glass fiber-reinforced thermoset resin is considered which is produced by the sheet molding compound (SMC) process. Related to the production process, the samples considered in this work exhibit an anisotropic fiber orientation distribution which highly affects the thermomechanical properties. The thermoviscoelastic material behavior of three selected samples is characterized by means of dynamic mechanical analysis. These tests show the temperature-dependent elastic modulus and the glass transition of the composite. Measurements of the thermal expansion of the SMC composite provide data on the coefficient of thermal expansion (CTE). These experimental investigations provide data for the thermoelastic material modeling. Aiming at the prediction of the effective thermal and mechanical properties, a Hashin–Shtrikman-based homogenization method is presented. Based on an eigenstrain formulation, the effective Young’s modulus and CTE are computed in two steps. Moreover, the mean-field method is given in dependence of a variable reference stiffness allowing to tailor the approach to the material system. The influence of this variable reference stiffness on the effective quantities as well as the predicted behavior is analyzed with respect to the experiments. The presented numerical results are in good agreement with the experimental data.

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Topolov, Vitaly Yu, Sergei V. Glushanin e Alexander A. Panich. "Hydrostatic Parameters and Domain Effects in Novel 2-2 Composites Based on PZN-0.12PT Single Crystals". Smart Materials Research 2011 (18 aprile 2011): 1–10. http://dx.doi.org/10.1155/2011/173064.

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Abstract (sommario):

A novel 0.88Pb(Zn1/3Nb2/3)O3-0.12PbTiO3 crystal/polymer composite with 2-2 connectivity is studied at variable orientations of spontaneous polarisation vector of the crystal component. Orientation and volume-fraction dependences of the hydrostatic piezoelectric coefficients dh*, eh*, and gh* and hydrostatic electromechanical coupling factor kh* are related to the important role of the piezoelectric and elastic anisotropy of single-domain layers of the 2-2 composite. The record value of |eh∗|≈77 C/m2 near the absolute-minimum point and the correlation between the hydrostatic (eh*) and piezoelectric (e3j*) coefficients and between the hydrostatic (gh*) and piezoelectric (g3j*) coefficients are first established. This discovery is of value for hydrostatic and piezotechnical applications. The hydrostatic performance of the composite based on the single-domain 0.88Pb(Zn1/3Nb2/3)O3-0.12PbTiO3 crystal is compared to the performance of the 2–2 composites based on either the same polydomain crystal or the related single-domain crystal.

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45

Baranger, Emmanuel. "Accounting for frictional contact in an anisotropic damage model based on compliance tensorial variables, illustration on ceramic matrix composites". International Journal of Damage Mechanics 28, n. 8 (24 novembre 2018): 1150–69. http://dx.doi.org/10.1177/1056789518812932.

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Abstract (sommario):

Ceramic matrix composites have good thermomechanical properties at high or very high temperatures. The modeling of the crack networks associated to the degradation of such composites using damage mechanics is not straightforward. The main reason is the presence of a crack network mainly oriented by the loading direction, which is a priori unknown. To model this, compliance tensorial damage variables are used in a thermodynamic potential able to account for crack closure effects (unilateral contact). The damage kinematic is initially completely free and imposed by the evolution laws. The key point of the present paper is to account for friction in such cracks that can result in an apparent activation/deactivation of the shear damage. The initial model is enriched with an inelastic strain and a friction law. The plasticity criterion is expressed only using tensorial variables. The model is identified and illustrated on multiaxial data obtained at ONERA on tubes loaded in tension and torsion.

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46

Baranger, Emmanuel. "Extension of a fourth-order damage theory to anisotropic history: Application to ceramic matrix compostites under a multi-axial non-proportional loading". International Journal of Damage Mechanics 27, n. 2 (19 dicembre 2016): 238–52. http://dx.doi.org/10.1177/1056789516674766.

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Abstract (sommario):

Ceramic matrix composites have good thermo-mechanical properties at high or very high temperatures. The alliance of two brittle materials (e.g. SiC fibers and SiC matrix) via an interface allows a pseudo-ductile macroscopic behavior due to crack deviation. The modeling of the crack networks using damage mechanics is not straight forward. The main reason is the presence of a crack network oriented by the loading direction, which is not known a priori. The aim of this paper is to extend an anisotropic damage model able to describe such behaviors to multi-axial loadings. For that, compliance-like tensorial damage variables are used in a thermodynamic potential able to account for crack closure effects. The damage kinematic is initially completely free and imposed by the evolution laws. The key point of the present paper is to account for an anisotropic history of damage. The results obtained are put in relation to alternate torsion tests performed on SiC/SiC tubes and richly instrumented.

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Zubkov, V. I., e V. I. Shcheglov. "Magnetic susceptibility of a composite medium with variable parameters that consists of arbitrarily oriented anisotropic ferrite particles". Journal of Communications Technology and Electronics 55, n. 4 (aprile 2010): 457–64. http://dx.doi.org/10.1134/s1064226910040121.

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48

Fazzolari, Fiorenzo Adolfo, e Erasmo Carrera. "Thermo-Mechanical Buckling Analysis of Anisotropic Multilayered Composite and Sandwich Plates by Using Refined Variable-Kinematics Theories". Journal of Thermal Stresses 36, n. 4 (3 aprile 2013): 321–50. http://dx.doi.org/10.1080/01495739.2013.770642.

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49

Kaldar-ool, A. K. B., R. N. Sandan e A. Kh H. Mongush. "Elastic con- stants of cylindrically anisotropic material". Vestnik Tomskogo gosudarstvennogo arkhitekturno-stroitel'nogo universiteta. JOURNAL of Construction and Architecture 26, n. 3 (13 giugno 2024): 158–69. http://dx.doi.org/10.31675/1607-1859-2024-26-3-158-169.

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Abstract (sommario):

This article examines new cylindrically anisotropic materials, including winding composite materials reinforced with various fiber, and a mathematical solution of the fourth-order partial differential equation with two variables in polar coordinates.Purpose: Ther aim of this work is to study anisotropy properties of composite materials with cylindrical anisotropy.Methodology/approach: Foe a solution, equations are translated into Cartesian coordinates, and stress functions are used as a sum of polynomials. As a result of the solution, two relations are obtained between the elastic constants in the main direction of anisotropy, i.e., elasticity parameters. These parameters are important to determine the mechanical properties of anisotropic material.Research findings: New high-strength composite materials are improved to apply in new technologies for building design and construction, high-strength structures are obtained using synthetic composite materials.Originality/value: Elastic constants for cylindrically anisotropic materials represent an innovative approach to determine the properties of composite materials with a flat anisotropy scheme, which make it easier and more efficient to determine elasticity parameters and strength in an arbitrary direction of coordinate axes.

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Rudykh, S., K. Bhattacharya e G. deBotton. "Multiscale instabilities in soft heterogeneous dielectric elastomers". Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 470, n. 2162 (8 febbraio 2014): 20130618. http://dx.doi.org/10.1098/rspa.2013.0618.

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The development of instabilities in soft heterogeneous dielectric elastomers is investigated. Motivated by experiments and possible applications, we use in our analysis the physically relevant referential electric field instead of electric displacement. In terms of this variable, a closed form solution is derived for the class of layered neo-Hookean dielectrics. A criterion for the onset of electromechanical multiscale instabilities for the layered composites with anisotropic phases is formulated. A general condition for the onset of the macroscopic instability in soft multiphase dielectrics is introduced. In the example of the layered dielectrics, the essential influence of the microstructure on the onset of instabilities is revealed. We found that: (i) macroscopic instabilities dominate at moderate volume fractions of the stiffer phase, (ii) interface instabilities appear at small volume fractions of the stiffer phase and (iii) instabilities of a finite scale, comparable to the microstructure size, occur at large volume fractions of the stiffer phase. The latest new type of instabilities does not appear in the purely mechanical case and dominates in the region of large volume fractions of the stiff phase.

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