Polymers

Research

11 pages, 7495 KiB

Open AccessArticle

A New Method for the Dynamics Analysis of Super-Elastic-Plastic Foams under Inhomogeneous Loading and Unloading Conditions

by Jiaxuan Chen, Fude Lu, Mingqi Wang and Shuangxi Xiang

Polymers 2024, 16(17), 2489; https://doi.org/10.3390/polym16172489 - 31 Aug 2024

Viewed by 487

Abstract

In this research, a new computational method was proposed for describing the mechanical behavior of super-elastic-plastic foams under inhomogeneous compressive impacts. The method regarded the foam material as composed of two typical mechanical properties superimposed multiple times: one was the hyper-elastic layer, and [...] Read more.

In this research, a new computational method was proposed for describing the mechanical behavior of super-elastic-plastic foams under inhomogeneous compressive impacts. The method regarded the foam material as composed of two typical mechanical properties superimposed multiple times: one was the hyper-elastic layer, and the other was the elastoplastic layer. The hyper-elastic layer and the elastoplastic layer were interwoven and overlapped, divided into double-layer, four-layer, and six-layer configurations to characterize the foam material. After the equivalent layering of the foam, by comparing the results of the four-layer and six-layer divisions, it was found that when the layering reached four layers, the foam performance curve had already converged. The study utilized the HYPERFOAM model and Mullins effect in the ABAQUS software to establish the constitutive relationship of the hyper-elastic layer. It adopted the Crushable foam model to develop the constitutive relationship of the elastoplastic layer. Under uniaxial compression conditions, quasi-static and intermediate strain rate compression tests were performed on polyethylene (PE) foam materials with three different densities. Based on the experimental results, the parameter values of the hyper-elastic-plastic foam model in the ABAQUS code were determined. By comparing the computational results and the experimental results, the established finite element (FE) model was validated using the mechanical behavior of indentation and compression tests. The results showed that this method could effectively describe the complex mechanical behavior and residual deformation of hyper-elastic-plastic foam packaging materials under non-uniform compression, and the experimental and simulation results agreed well, proving the reliability of this method. Full article

(This article belongs to the Special Issue Multiscale Modeling and Simulation of Polymer-Based Composites)

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17 pages, 8750 KiB

Open AccessArticle

A Multiscale Modeling and Experimental Study on the Tensile Strength of Plain-Woven Composites with Hybrid Bonded–Bolted Joints

by Jianwei Shi, Junwei Zhang, Kou Du, Qiming Guo, Yuliang Hou and Cheng Dong

Polymers 2024, 16(14), 2074; https://doi.org/10.3390/polym16142074 - 20 Jul 2024

Viewed by 662

Abstract

CFRP hybrid bonded–bolted (HBB) joints combine the advantages of traditional joining methods, namely adhesive bonding, and bolting, to achieve optimal connection performance, making them the most favored connection method. The structural parameters of CFRP HBB joints, including overlap length, bolt-hole spacing, and fit [...] Read more.

CFRP hybrid bonded–bolted (HBB) joints combine the advantages of traditional joining methods, namely adhesive bonding, and bolting, to achieve optimal connection performance, making them the most favored connection method. The structural parameters of CFRP HBB joints, including overlap length, bolt-hole spacing, and fit clearance relationships, have a complex impact on connection performance. To enhance the connectivity performance of joint structures, this paper develops a multiscale finite element analysis model to investigate the impact of structural parameters on the strength of CFRP HBB joint structures. Coupled with experimental validation, the study reveals how changes in structural parameters affect the unidirectional tensile failure force of the joints. Building on this, an analytical approach and inverse design methodology for the mechanical properties of CFRP HBB joints based on deep supervised learning algorithms are developed. Neural networks accurately and efficiently predict the performance of joints with unprecedented combinations of parameters, thus expediting the inverse design process. This research combines experimentation and multiscale finite element analysis to explore the unknown relationships between the mechanical properties of CFRP HBB joints and their structural parameters. Furthermore, leveraging DNN neural networks, a rapid calculation method for the mechanical properties of hybrid joints is proposed. The findings lay the groundwork for the broader application and more intricate design of composite materials and their connection structures. Full article

(This article belongs to the Special Issue Multiscale Modeling and Simulation of Polymer-Based Composites)

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17 pages, 9391 KiB

Open AccessArticle

Digital Image Correlation and Ultrasonic Lamb Waves for the Detection and Prediction of Crack-Type Damage in Fiber-Reinforced Polymer Composite Laminates

by Elena Jasiūnienė, Tomas Vaitkūnas, Justina Šeštokė and Paulius Griškevičius

Polymers 2024, 16(14), 1980; https://doi.org/10.3390/polym16141980 - 11 Jul 2024

Viewed by 632

Abstract

The possibility of using the Digital Image Correlation (DIC) technique, along with Lamb wave analysis, was investigated in this study for damage detection and characterization of polymer carbon fiber (CFRP) composites with the help of numerical modeling. The finite element model (FEM) of [...] Read more.

The possibility of using the Digital Image Correlation (DIC) technique, along with Lamb wave analysis, was investigated in this study for damage detection and characterization of polymer carbon fiber (CFRP) composites with the help of numerical modeling. The finite element model (FEM) of the composite specimen with artificial damage was developed in ANSYS and validated by the results of full-field DIC strain measurements. A quantitative analysis of the damage detection capabilities of DIC structure surface strain measurements in the context of different defect sizes, depths, and orientation angles relative to the loading direction was conducted. For Lamb wave analysis, a 2D spatial-temporal spectrum analysis and FEM using ABAQUS software were conducted to investigate the interaction of Lamb waves with the different defects. It was demonstrated that the FEM updating procedure could be used to characterize damage shape and size from the composite structure surface strain field from DIC. DIC defect detection capabilities for different loadings are demonstrated for the CFRP composite. For the identification of any composite defect, its characterization, and possible further monitoring, a methodology based on initial Lamb wave analysis followed by DIC testing is proposed. Full article

(This article belongs to the Special Issue Multiscale Modeling and Simulation of Polymer-Based Composites)

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21 pages, 25167 KiB

Open AccessArticle

Numerical Analysis of Laminated Veneer Lumber Beams Strengthened with Various Carbon Composites

by Michał Marcin Bakalarz and Paweł Grzegorz Kossakowski

Polymers 2024, 16(12), 1697; https://doi.org/10.3390/polym16121697 - 14 Jun 2024

Viewed by 667

Abstract

Among the many benefits of implementing numerical analysis on real objects, economic and environmental considerations are likely the most important ones. Nonetheless, it is also crucial to constrain the duration and space necessary for conducting experimental investigations. Although these benefits are clear, the [...] Read more.

Among the many benefits of implementing numerical analysis on real objects, economic and environmental considerations are likely the most important ones. Nonetheless, it is also crucial to constrain the duration and space necessary for conducting experimental investigations. Although these benefits are clear, the applicability of such models must be appropriately verified. This research subjected validation of numerical models depicting the behavior of unstrengthened and strengthened laminated veneer lumber (LVL) beams. As a reinforcement, a carbon fiber reinforced polymer (CFRP) sheet and laminates were used. Experiments were conducted on full-scale members within the framework of the so-called four-point bending testing method. Numerical simulations were performed using the Abaqus software. Two types of material models were examined for laminated veneer lumber: linearly elastic and linearly elastic–perfectly plastic with Hill’s yield criterion. A distinction was made in the material properties of carbon composites based on their location on the height of the cross-section. The outlined numerical models accurately depict the behavior of real structural elements. The precision of predicting load-bearing capacity amounts to a few percent for strengthened beams and a maximum of eleven percent for unstrengthened beams. The relative deviation between numerical and experimental values of bending stiffness was at a maximum of seven percent. Applying the elastic–plastic model enables accurate representation of the load versus deflection relation and the distribution of stress and deformation of strengthened beams. Based on the findings, directives were provided for further optimization of the positioning of composite reinforcement along the span of the beam. Reinforcement design of existing laminated veneer lumber members can be made using presented methodology. Full article

(This article belongs to the Special Issue Multiscale Modeling and Simulation of Polymer-Based Composites)

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20 pages, 25840 KiB

Open AccessArticle

Experimental and Numerical Investigation of Prepreg-RTM Co-Curing Molding Composite Bolted T-Joint under Bending Load

by Tao Zhang, Zhitao Luo, Kenan Li and Xiaoquan Cheng

Polymers 2024, 16(7), 1018; https://doi.org/10.3390/polym16071018 - 8 Apr 2024

Cited by 2 | Viewed by 735

Abstract

A set of polymer composite bolted T-joints with a novel configuration consisting of an internal skeleton and external skin was fabricated using a prepreg-RTM co-curing molding process. Experiments were conducted to study their mechanical properties under a bending load. A finite element model [...] Read more.

A set of polymer composite bolted T-joints with a novel configuration consisting of an internal skeleton and external skin was fabricated using a prepreg-RTM co-curing molding process. Experiments were conducted to study their mechanical properties under a bending load. A finite element model with a polymer resin area between the skin and skeleton was established and verified by the experimental results. Then, the damage propagation process and failure mechanism of the joint and the influence of three factors related to the layer characteristics of the skin and skeleton were investigated by the validated models. The results show that the bending stiffness and the yield limit load of the novel composite T-joint are 0.81 times and 1.65 times that of the 2A12 aluminum T-joint, respectively, while at only 55.4% of its weight. The damage of the joint is initiated within the resin area and leads to the degradation of the joint’s bending performance. The preferred stacking sequence of the skeleton is [0/+45/90/−45]_ns when primarily subjected to bending loads. The decrease in the bending performance is within 5% of the inclining angle of the skeleton, less than 12 degrees. The more 90° layers in the skin, the better the bending performance of the joints, while the more 0° layers, the poorer the bending performance. Full article

(This article belongs to the Special Issue Multiscale Modeling and Simulation of Polymer-Based Composites)

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16 pages, 3768 KiB

Open AccessArticle

Computational Optimization of Sandwich Silicone Rubber Composite for Improved Thermal Conductivity and Electrical Insulation

by Abdulrahman A. Alghamdi

Polymers 2024, 16(5), 616; https://doi.org/10.3390/polym16050616 - 23 Feb 2024

Cited by 2 | Viewed by 1301

Abstract

The efficient dissipation of heat has emerged as a crucial concern for modern electronic devices, given the continuous increase in their power density and consumption. Thus, the utilization of thermally conductive but electrically insulating silicone rubber composites as a thermal interface material has [...] Read more.

The efficient dissipation of heat has emerged as a crucial concern for modern electronic devices, given the continuous increase in their power density and consumption. Thus, the utilization of thermally conductive but electrically insulating silicone rubber composites as a thermal interface material has garnered significant interest. In this study, the effects of the filler volume fraction, filler orientation, layer volume fractions, layer configuration, and a number of layers on the thermal conductivity and electrical resistivity of silicone rubber composites were examined using a multiscale finite element modeling strategy. The results demonstrated that modification of the filler orientation can change the thermal conductivity by 28 and 21 times in the in-plane and through-thickness directions, respectively. The in-plane thermal conductivities of silicone rubber/boron nitride and silicone rubber/expanded graphite layers exhibit a percolation phenomenon at filler volume fractions of 35% and 30%, respectively. The electrical resistivity of the composite increases exponentially with a decrease in the number of layers. Full article

(This article belongs to the Special Issue Multiscale Modeling and Simulation of Polymer-Based Composites)

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18 pages, 5042 KiB

Open AccessArticle

Nanocomposites Based on Pyrolyzed Polyacrylonitrile Doped with FeCoCr/C Transition Metal Alloy Nanoparticles: Synthesis, Structure, and Electromagnetic Properties

by Irina Zaporotskova, Dmitriy Muratov, Lev Kozhitov, Alena Popkova, Natalia Boroznina, Sergey Boroznin, Andrey Vasiliev, Vitaly Tarala and Evgeny Korovin

Polymers 2023, 15(17), 3596; https://doi.org/10.3390/polym15173596 - 30 Aug 2023

Cited by 4 | Viewed by 1166

Abstract

In the last decade, the development of new materials that absorb electromagnetic radiation (EMR) has received research interest as they can significantly enhance the performance of electronic devices and prevent adverse effects caused by electromagnetic pollution. Electromagnetic radiation absorbers with a low weight [...] Read more.

In the last decade, the development of new materials that absorb electromagnetic radiation (EMR) has received research interest as they can significantly enhance the performance of electronic devices and prevent adverse effects caused by electromagnetic pollution. Electromagnetic radiation absorbers with a low weight and small thickness of the absorber layer, good absorption capacity, and a wide frequency response bandwidth are highly demanded. Here, for the first time, the properties of polymer nanocomposites FeCoCr/C synthesized by doping FeCoCr alloy nanoparticles into a polymer matrix of pyrolyzed polyacrylonitrile are investigated. An analysis of the magnetic properties of FeCoCr/C nanocomposites showed that increasing the synthesis temperature increased the specific magnetization and coercive force values of the FeCoCr/C nanocomposites. The dependence between the ratio of metals in the precursor of pyrolyzed polyacrylonitrile and the electromagnetic and wave-absorbing properties of FeCoCr/C nanocomposites is considered, and the results of complex dielectric and magnetic permeability measurements are analyzed. It is found that the most promising of all the studied materials are those obtained at T = 700 °C with the ratio of metals Fe:Co:Cr = 35:35:30. Full article

(This article belongs to the Special Issue Multiscale Modeling and Simulation of Polymer-Based Composites)

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17 pages, 6779 KiB

Open AccessArticle

A New Uniaxial Tensile Model for Foam Metal/Epoxy Interpenetrated Phase Composites

by Xiaoxing Wang, Lixin Zhang, Yu Zhao and Huijian Li

Polymers 2023, 15(4), 812; https://doi.org/10.3390/polym15040812 - 6 Feb 2023

Cited by 3 | Viewed by 1489

Abstract

Foam metal/epoxy interpenetrating phase composite is a new type of composite material with interpenetrating continuity in composition, which exhibits different intrinsic relationships under different stress states in tension and compression, and it is necessary to study the intrinsic relationships in the tensile state [...] Read more.

Foam metal/epoxy interpenetrating phase composite is a new type of composite material with interpenetrating continuity in composition, which exhibits different intrinsic relationships under different stress states in tension and compression, and it is necessary to study the intrinsic relationships in the tensile state in depth. A mesoscopic damage-based tensile intrinsic model is developed, and the elasto-plastic tensile intrinsic equations of the representative volume element are derived based on small deformation theory and total strain theory, as well as the assumptions of equal stress and equal strain. The tensile strengths of nickel–iron foam/epoxy interpenetrated phase composites in three different sizes and their constituent phases were measured, and it was shown in the results that the composite of three-dimensional network interpenetration with high-strength foam metal and epoxy resin formed a weak surface inside the material, and did not significantly improve the tensile strength of the composites. The tensile instantonal equations and damage instantonal equations of nickel–iron foam/epoxy interpenetrated phase composites were predicted by the method of inversion, and the applicability and high accuracy of the tensile intrinsic model were verified in comparison with the measured results. Full article

(This article belongs to the Special Issue Multiscale Modeling and Simulation of Polymer-Based Composites)

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