Applied Sciences

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19 pages, 6668 KiB

Open AccessArticle

Discrete Element Simulation of the Shear Behavior of Binary Mixtures Composed of Spherical and Cubic Particles

by Yun Huang, Weichen Sun, Qiang Xie, Hongyi You and Kai Wu

Appl. Sci. 2023, 13(16), 9163; https://doi.org/10.3390/app13169163 - 11 Aug 2023

Cited by 1 | Viewed by 1070

This research paper presents an investigation into the shear behavior of binary mixtures composed of cubic and spherical particles, employing the discrete element method (DEM) through triaxial tests simulations. A range of binary particle samples with varying volume fractions of cubic and spherical [...] Read more.

This research paper presents an investigation into the shear behavior of binary mixtures composed of cubic and spherical particles, employing the discrete element method (DEM) through triaxial tests simulations. A range of binary particle samples with varying volume fractions of cubic and spherical particles is generated for analysis. The study primarily focuses on examining the contracting-dilatancy relationship of binary granular material samples by scrutinizing deviatoric stress and volumetric strain curves, while considering the influence of confining pressure, initial porosity, and particle size ratio. Furthermore, the paper sheds light on the evolution of microstructures during the shearing process by presenting coordination numbers and rotational velocity fields for different particle types (overall particles, cubic particles, spherical particles), as well as between cubic-spherical particles. The findings demonstrate the substantial impact of both the volume fraction of cubic particles and the particle size ratio on the shear behavior of binary particles at both macroscopic and microscopic scales. Additionally, a comprehensive investigation reveals the dependence of anisotropy in normal contact forces, tangent contact forces, and contact orientations on the volume fraction of cubic particles. Full article

(This article belongs to the Special Issue Modeling and Simulation of Composite Materials and Structures)

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24 pages, 14799 KiB

Open AccessArticle

Experimental Study on the Properties of Simulation Materials for an Aquifuge for a Fluid–Solid Coupling Physical Similarity Model Test

by Xiong Shen, Jizu Li, Guorui Feng, Dekang Zhao and Qin Liu

Appl. Sci. 2023, 13(15), 8667; https://doi.org/10.3390/app13158667 - 27 Jul 2023

Cited by 2 | Viewed by 980

Abstract

In order to meet the special requirements of physical and mechanical strength and high water resistance of similar material in aquifuge (aquitard) strata for the testing of the fluid–solid coupling physical similarity model for a mine water inrush. Based on the similarity theory [...] Read more.

In order to meet the special requirements of physical and mechanical strength and high water resistance of similar material in aquifuge (aquitard) strata for the testing of the fluid–solid coupling physical similarity model for a mine water inrush. Based on the similarity theory of solid–fluid coupling in equivalent homogeneous continuous media, a new type of aquifuge simulation material was developed, which used river sand as the skeleton of the material, gypsum and calcium carbonate powder as the auxiliary cementing agent, and paraffin wax and petroleum jelly as the waterproof cementing agent. Similar materials of aquifuge (aquitard) strata are created according to a specific proportion of the components and an established technological process. Through orthogonal tests and systematic analysis, the influence mechanism of the different proportions of the raw materials on the variation of the physical–mechanical strength and hydraulic parameters is studied in this paper. The experimental results demonstrate when the mass ratio of solid material to liquid material is 8:1 and 9:1, the mass ratios of river sand, calcium carbonate, and gypsum is 30:3:7, 30:3:7, and 50:3:7, and the mass ratios of paraffin wax to petroleum jelly are 1:2, 1:1, and 2:1, respectively. The controlled ranges of uniaxial compressive strength, softening coefficient, and permeability coefficient of the similar materials are 16.99–426.47 kPa, 0.660–0.805, and 1.01 × 10⁻⁷–8.34 × 10⁻⁷ cm/s, respectively. The above data show that the materials have the characteristics of low strength, controllable water absorption, and low permeability. Full article

(This article belongs to the Special Issue Modeling and Simulation of Composite Materials and Structures)

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14 pages, 5673 KiB

Open AccessArticle

Buckling Enhancement Analysis of Auxetic Laminated Rectangular Plate under Uniaxial Compression

by Kai Wang, Feng Wan, Ling Luo, Pengyu Cao, Lei Han and Peng Jin

Appl. Sci. 2023, 13(10), 6244; https://doi.org/10.3390/app13106244 - 19 May 2023

Cited by 1 | Viewed by 1008

Abstract

The buckling enhancement of the negative Poisson’s ratio (NPR) effect on a laminated plate under uniaxial compression with an in-plane translational restraint is investigated in this paper. According to the buckling equation of an orthotropic plate under biaxial compression, the critical buckling load [...] Read more.

The buckling enhancement of the negative Poisson’s ratio (NPR) effect on a laminated plate under uniaxial compression with an in-plane translational restraint is investigated in this paper. According to the buckling equation of an orthotropic plate under biaxial compression, the critical buckling load of an NPR-laminated composite under uniaxial compression can be increased due to the induced tension force on the unloaded direction. Instead of layer angles and stacking sequence, the NPR envelope and buckling load enhancement are studied using lamination parameters in this paper. The Poisson’s ratio contours are given in the feasible region of membrane lamination parameters. The results show that the negative Poisson’s ratios are more sensitive to

V_{3}^{A}

, which represents the unbalance degree of the laminate. Furthermore, the buckling loads for various Poisson’s ratio layups are investigated, and it is concluded that the buckling load increases with a decrease in Poisson’s ratio for the laminated rectangular plate considering in-plane translational restraint. Finally, the inverse problem of deciding the laminate configuration to target the lamination parameters is solved using the particle swarm optimization (PSO) algorithm. Full article

(This article belongs to the Special Issue Modeling and Simulation of Composite Materials and Structures)

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15 pages, 2413 KiB

Open AccessArticle

Deformation Performance of CFRP-Strengthened Corroded Reinforced Concrete Beams after Fatigue Loading

by Zhimei Zhang and Tao Li

Appl. Sci. 2023, 13(10), 6198; https://doi.org/10.3390/app13106198 - 18 May 2023

Cited by 1 | Viewed by 1030

Abstract

To study the deformation performance of CFRP-strengthened corroded RC (reinforced concrete) beams under fatigue loading, a numerical analysis method based on the fatigue damage failure process was used, and the fatigue constitutive models of each material were used as the basis. The finite [...] Read more.

To study the deformation performance of CFRP-strengthened corroded RC (reinforced concrete) beams under fatigue loading, a numerical analysis method based on the fatigue damage failure process was used, and the fatigue constitutive models of each material were used as the basis. The finite element software ABAQUS was used to model and analyze the CFRP-strengthened corroded RC beams, and the degradation of bond performance between rusted reinforcement and concrete was considered in the simulation. Then, the flexural stiffness calculation method of CFRP-strengthened corroded RC beams was analyzed. Based on the validation of the finite element model, a regression analysis was performed on the mid-span deflection data of the simulated beam to establish a formula for calculating the mid-span deflection of CFRP-strengthened corroded RC beams under fatigue loading. Finally, the collected experimental data were compared with the calculation results using the mid-span deflection formula, which was validated to confirm its accuracy and reliability. The research results show that the mean, standard deviation and coefficient of variation of the ratio of experimental to calculated values were 0.95, 0.09 and 0.10, respectively, indicating that the calculated values of the proposed mid-span deflection formulation are in good agreement with the experimental values, which proves the correctness and high accuracy of the proposed formula for calculating the mid-span deflection. The formula can provide a theoretical basis for the evaluation of the deformation performance of CFRP-strengthened corroded RC beams under fatigue loading. Full article

(This article belongs to the Special Issue Modeling and Simulation of Composite Materials and Structures)

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14 pages, 7803 KiB

Open AccessArticle

On the Use of Microstructure Characteristics to Predict Metal Matrix Composites’ Macroscopic Mechanical Behavior

by Ioannis Markopoulos, Leonidas-Alexandros Kouris and Avraam Konstantinidis

Appl. Sci. 2023, 13(8), 4989; https://doi.org/10.3390/app13084989 - 16 Apr 2023

Cited by 1 | Viewed by 1696

Abstract

In recent decades, the construction of statistically similar representative volume elements (SSRVEs) of materials for use in numerical analyses has been accomplished utilizing various methods, tools, and frameworks. Such a framework is introduced in this work, where the creation of 3D SSRVEs of [...] Read more.

In recent decades, the construction of statistically similar representative volume elements (SSRVEs) of materials for use in numerical analyses has been accomplished utilizing various methods, tools, and frameworks. Such a framework is introduced in this work, where the creation of 3D SSRVEs of metal matrix composites was investigated to assess their mechanical properties with reference to the material’s microstructure. The material studied was a composite based on AA7075 alloy reinforced with carbon fibers, with volume fractions of 0%, 4%, 8%, and 12%. The statistics of the alloy’s microstructure were extracted by segmenting an SEM image and fitting the precipitate particles’ sizes with respect to a lognormal distribution. The open-source software DREAM.3D was used to construct 3D ensembles and the Abaqus FEA software was employed for the mechanical testing simulations. By plotting the tensile stress–strain curves for the composites, it was found that the elastic modulus increased with the fibers’ volume fraction, obeying the rule of mixtures for discontinuous fibrous composites. The fiber efficiency factors were also calculated. The yield stresses of the composites were found and compared to the ones expected according to the shear-lag model, indicating major differences. Full article

(This article belongs to the Special Issue Modeling and Simulation of Composite Materials and Structures)

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19 pages, 15385 KiB

Open AccessArticle

Elaboration of a Multi-Objective Optimization Method for High-Speed Train Floors Using Composite Sandwich Structures

by Mortda Mohammed Sahib and György Kovács

Appl. Sci. 2023, 13(6), 3876; https://doi.org/10.3390/app13063876 - 18 Mar 2023

Cited by 7 | Viewed by 1804

Abstract

The transportation industry needs lightweight structures to meet economic and environmental demands. Composite sandwich structures offer high stiffness and low mass, making them ideal for weight reduction in high-speed trains. The objective of this research is to develop a method of weight and [...] Read more.

The transportation industry needs lightweight structures to meet economic and environmental demands. Composite sandwich structures offer high stiffness and low mass, making them ideal for weight reduction in high-speed trains. The objective of this research is to develop a method of weight and cost optimization for floors of high-speed trains. The studied sandwich floor structure consists of Fiber Metal Laminates (FML) face sheets and a honeycomb core. Different variations of FMLs were investigated to define the optimal sandwich structure for minimum weight and cost. The Neighborhood Cultivation Genetic Algorithm (NCGA) was used to search the design space, and the Finite Element Method (FEM) was used to construct the optimal design of the train car floor panel. The FEM and optimization results had a maximum difference about 11%. The study concluded that using face sheets made entirely of Fiber-Reinforced Plastic (FRP) or Fiber Metal Laminates (FMLs) resulted in significant weight savings of approximately 62% and 32%, respectively, compared to a sandwich structure made entirely of aluminum, but a lighter structure was associated with higher cost. The main contribution of this study is the elaboration of a multi-objective optimization method that utilizes a wide range of constituent materials and structural components in order to construct weight- and cost-optimized sandwich structures. Full article

(This article belongs to the Special Issue Modeling and Simulation of Composite Materials and Structures)

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24 pages, 15692 KiB

Open AccessArticle

The Using of the Multilayer Plate Concept in the Calculus of Functionally Graded Plates

by Vasile Nastasescu

Appl. Sci. 2022, 12(21), 10695; https://doi.org/10.3390/app122110695 - 22 Oct 2022

Cited by 4 | Viewed by 1195

Abstract

In the calculus of functionally graded plates, the concept of multilayer plate is often used. For the use of this concept in this calculus, the continuous variation of the respective properties is replaced with a step variation. The first problem that arises in [...] Read more.

In the calculus of functionally graded plates, the concept of multilayer plate is often used. For the use of this concept in this calculus, the continuous variation of the respective properties is replaced with a step variation. The first problem that arises in front of the user is related to the number of layers, which must be a finite and reasonably large number, to be accessible to the current calculus and to ensure the necessary accuracy of the results (under 5%). Another problem, generally poorly substantiated, is the one related to the assumption of a constant value of the Poisson’s ratio (usually 0.30 for the considered materials) over the entire plate thickness. The paper also contains a quantitative study of the influence of the Poisson ratio (4,…,10%), whose variation can be neglected, but only in certain circumstances. The presentation and substantiation of how to use the multilayer plate concept through models, methods and methodologies, along with the substantiation of the choice of the number of layers and the influence of the Poisson’s ratio, represent the main evidence of the originality of this work. The proposed numerical models are based on the use of common 3D finite elements. The software Ansys is used, which offers a multilayer finite element, which is taken into account in the comparative analysis of the results. The validation of the results is carried out by comparison with the analytical solution. The objective and purpose of this paper, that of completing the palette of achievements regarding the calculus of functionally graded plates, without modification of the stiffness matrices of the finite elements and using existing software products, are fulfilled. Full article

(This article belongs to the Special Issue Modeling and Simulation of Composite Materials and Structures)

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15 pages, 6841 KiB

Open AccessArticle

Simulation, Fabrication and Testing of UAV Composite Landing Gear

by Camil Lancea, Lucia-Antoneta Chicos, Sebastian-Marian Zaharia, Mihai-Alin Pop, Ionut Stelian Pascariu, George-Razvan Buican and Valentin-Marian Stamate

Appl. Sci. 2022, 12(17), 8598; https://doi.org/10.3390/app12178598 - 27 Aug 2022

Cited by 10 | Viewed by 5668

Abstract

This study concerns the use of the fused filament fabrication technique to create models of the landing gear of an unmanned aircraft. These components are made of filament with short fibers (chopped fibers) of carbon fiber and fiberglass. In order to identify the [...] Read more.

This study concerns the use of the fused filament fabrication technique to create models of the landing gear of an unmanned aircraft. These components are made of filament with short fibers (chopped fibers) of carbon fiber and fiberglass. In order to identify the material with the high mechanical strength, the designed models were subjected to a finite element analysis and to a three-point bending test, followed by a microscopic examination of the tested components. Following a comparative study, both the finite element analysis results and the three-point bending test results provided similar results, with a relative error of 2%, which is acceptable in the aviation field. After analyzing all the results, it was found that the carbon fiber-reinforced polymer material has the highest mechanical performance, with a bending strength of 1455 MPa. Among the fused filament fabricated landing gears, the one with the best mechanical performance was polyethylene terephthalate with short carbon fiber, which had a bending strength of 118 MPa. Microscopic analysis of the landing gear models, manufactured by the fused filament fabrication process, indicated the typical defects of composite filaments: voids and interlayer voids. Full article

(This article belongs to the Special Issue Modeling and Simulation of Composite Materials and Structures)

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