Editorial

3 pages, 192 KiB

Open AccessEditorial

Special Issue “Composite Materials in Design Processes”

by Giangiacomo Minak

Appl. Sci. 2020, 10(23), 8658; https://doi.org/10.3390/app10238658 - 03 Dec 2020

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Composite materials have been used in design since antiquity, as the description of the Ulises’ arch in the Odyssey suggests [...] Full article

(This article belongs to the Special Issue Composite Materials in Design Processes)

Research

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20 pages, 10902 KiB

Open AccessArticle

Is the Viscoelastic Sheet for Slamming Impact Ready to Be Used on Glass Fiber Reinforced Plastic Planning Hull?

by Patrick Townsend, Juan Carlos Suárez Bermejo, Paz Pinilla and Nadia Muñoz

Appl. Sci. 2020, 10(18), 6557; https://doi.org/10.3390/app10186557 - 19 Sep 2020

Cited by 2 | Viewed by 1818

Abstract

Planing hull vessel built with polymer matrix laminates and fiberglass reinforcements (GFRP) suffer structural damage due to the phenomenon of slamming during navigation, due to the impact of the boat hull on the free surface of the water at high speed. A modification [...] Read more.

Planing hull vessel built with polymer matrix laminates and fiberglass reinforcements (GFRP) suffer structural damage due to the phenomenon of slamming during navigation, due to the impact of the boat hull on the free surface of the water at high speed. A modification in the manufacture of the laminates for these fast boats is proposed, consisting of the insertion of an additional layer of a hybrid material, formed by elastomer encapsulated in an ABS polymer cell. Using GFRP specimens made from pre-impregnated material and reproducing the characteristic impacts of slamming, it is possible to compare the modified material with the introduction of the viscoelastic layers with the response under the same conditions as the unmodified laminates. Additionally, the panels have been tested using impacts due to weight drop at different energies, which allow determining the material damage threshold as a function of the energy absorbed, and to establish a comparison with the GFRP panels modified by observation in fluorescent light. It is verified that the proposal to reduce the effect of these impacts on the generation of damage to the material and its progression throughout the service life of the vessel is effective. Full article

(This article belongs to the Special Issue Composite Materials in Design Processes)

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14 pages, 3065 KiB

Open AccessArticle

Experimental Characterization of a High-Damping Viscoelastic Material Enclosed in Carbon Fiber Reinforced Polymer Components

by Marco Troncossi, Sara Taddia, Alessandro Rivola and Alberto Martini

Appl. Sci. 2020, 10(18), 6193; https://doi.org/10.3390/app10186193 - 06 Sep 2020

Cited by 16 | Viewed by 2625

Abstract

This work aims to identify the damping properties of a commercial viscoelastic material that can be embedded and cured between the layers of composite laminates. The material may be adopted for reducing the vibration response of composite panels, typically used in automotive and [...] Read more.

This work aims to identify the damping properties of a commercial viscoelastic material that can be embedded and cured between the layers of composite laminates. The material may be adopted for reducing the vibration response of composite panels, typically used in automotive and aerospace applications, e.g., as vehicle body shell components. In order to objectively estimate the actual potential to enhance the noise vibration and harshness aspects, the effects of the viscoelastic material on the modal parameters of carbon/epoxy thin panels are quantitatively assessed through experimental modal analysis. Two different experiments are conducted, namely impact hammer tests and shaker excitation measurements. Based on the results of the experimental campaign, the investigated material is confirmed as a promising solution for possibly reducing the severity of vibrations in composite panels, thanks to its high damping properties. Indeed, the presence of just one layer proves to triple the damping properties of a thin panel. An approximate damping model is derived from the measured data in order to effectively simulate the dynamic response of new design solutions, including thin composite panels featuring the viscoelastic material. Full article

(This article belongs to the Special Issue Composite Materials in Design Processes)

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12 pages, 4166 KiB

Open AccessFeature PaperArticle

Toughening Behavior of Carbon/Epoxy Laminates Interleaved by PSF/PVDF Composite Nanofibers

by Hamed Saghafi, Roberto Palazzetti, Hossein Heidary, Tommaso Maria Brugo, Andrea Zucchelli and Giangiacomo Minak

Appl. Sci. 2020, 10(16), 5618; https://doi.org/10.3390/app10165618 - 13 Aug 2020

Cited by 10 | Viewed by 2302

Abstract

This paper presents an investigation on fracture behavior of carbon/epoxy composite laminates interleaved with electrospun nanofibers. Three different mats were manufactured and interleaved, using only polyvinylidene fluoride (PVDF), only polysulfone (PSF), and their combination. Mode-I and Mode-II fracture mechanics tests were conducted on [...] Read more.

This paper presents an investigation on fracture behavior of carbon/epoxy composite laminates interleaved with electrospun nanofibers. Three different mats were manufactured and interleaved, using only polyvinylidene fluoride (PVDF), only polysulfone (PSF), and their combination. Mode-I and Mode-II fracture mechanics tests were conducted on virgin and nanomodified samples, and the results showed that PVDF and PSF nanofibers enhance the Mode-I critical energy release rate (G_IC) by 66% and 51%, respectively, while using a combination of the two registered a 78% increment. The same phenomenon occurred under Mode-II loading. SEM micrographs were taken, to investigate the toughening mechanisms provided by the nanofibers. Full article

(This article belongs to the Special Issue Composite Materials in Design Processes)

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17 pages, 5664 KiB

Open AccessArticle

Comparative Study of Glass Fiber Content Measurement Methods for Inspecting Fabrication Quality of Composite Ship Structures

by Zhiqiang Han, Sookhyun Jeong, Jackyou Noh and Daekyun Oh

Appl. Sci. 2020, 10(15), 5130; https://doi.org/10.3390/app10155130 - 26 Jul 2020

Cited by 15 | Viewed by 4832

Abstract

A comparative study of glass fiber content (Gc) measurement methods was conducted using actual glass fiber reinforced plastic laminates from the hull plate of a 26-ton yacht. Two prototype side hull plates with the design Gc (40 wt.%) and higher Gc (64 wt.%) [...] Read more.

A comparative study of glass fiber content (Gc) measurement methods was conducted using actual glass fiber reinforced plastic laminates from the hull plate of a 26-ton yacht. Two prototype side hull plates with the design Gc (40 wt.%) and higher Gc (64 wt.%) were prepared. Four methods were used to study the samples: the calculation method suggested by classification societies’ rules; two direct measurement methods using either calipers and scales or a hydrometer; and the burn-off method, wherein the resin matrix is combusted from the laminates. The results were compared and analyzed to identify the accuracy and benefits of each method. The rule calculation method was found to be effective if the quality of the manufacturing process is known. However, fabrication errors in the laminate structures cannot be detected. Additionally, while direct methods are used to measure the density of glass fibers using measurements of the densities of raw materials and laminates, the volume of inner defects occurring during the fabrication of laminates could not be considered. Finally, it was found that the burn-off method measures Gc and considers the defect volume (voids) inside laminates as well as the non-uniformity of the external shape. Full article

(This article belongs to the Special Issue Composite Materials in Design Processes)

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21 pages, 4650 KiB

Open AccessArticle

Numerical Analysis of the Influence of Empty Channels Design on Performance of Resin Flow in a Porous Plate

by Glauciléia M. C. Magalhães, Cristiano Fragassa, Rafael de L. Lemos, Liércio A. Isoldi, Sandro C. Amico, Luiz A. O. Rocha, Jeferson A. Souza and Elizaldo D. dos Santos

Appl. Sci. 2020, 10(11), 4054; https://doi.org/10.3390/app10114054 - 11 Jun 2020

Cited by 11 | Viewed by 2547

Abstract

This numerical study aims to investigate the influence of I and T-shaped empty channels’ geometry on the filling time of resin in a rectangular porous enclosed mold, mimicking the main operating principle of a liquid resin infusion (LRI) process. Geometrical optimization was conducted [...] Read more.

This numerical study aims to investigate the influence of I and T-shaped empty channels’ geometry on the filling time of resin in a rectangular porous enclosed mold, mimicking the main operating principle of a liquid resin infusion (LRI) process. Geometrical optimization was conducted with the constructal design (CD) and exhaustive search (ES) methods. The problem was subjected to two constraints (areas of porous mold and empty channels). In addition, the I and T-shaped channels were subjected to one and three degrees of freedom (DOF), respectively. Conservation equations of mass and momentum for modeling of resin/air mixture flow were numerically solved with the finite volume method (FVM). Interaction between the phases was considered with the volume of fluid method (VOF), and the effect of porous medium resistance in the resin flow was calculated with Darcy’s law. For the studied conditions, the best T-shaped configuration resulted in a filling time nearly three times lower than that for optimal I-shaped geometry, showing that the complexity of the channels benefited the performance. Moreover, the best T-shaped configurations were achieved for long single and bifurcated branches, except for configurations with skinny channels, which saw the generation of permanent voids. Full article

(This article belongs to the Special Issue Composite Materials in Design Processes)

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19 pages, 16309 KiB

Open AccessArticle

Multi-Objective Design Optimization of the Reinforced Composite Roof in a Solar Vehicle

by Ana Pavlovic, Davide Sintoni, Cristiano Fragassa and Giangiacomo Minak

Appl. Sci. 2020, 10(8), 2665; https://doi.org/10.3390/app10082665 - 12 Apr 2020

Cited by 26 | Viewed by 3737

Abstract

A multi-step and -objective design approach was used to optimize the photovoltaic roof in a multi-occupant racing vehicle. It permitted to select the best combination of design features (as shapes, widths, angles) in composite structures simultaneously balancing opposite requirements as static strength and [...] Read more.

A multi-step and -objective design approach was used to optimize the photovoltaic roof in a multi-occupant racing vehicle. It permitted to select the best combination of design features (as shapes, widths, angles) in composite structures simultaneously balancing opposite requirements as static strength and dynamic stiffness. An attention to functional requirements, as weight, solar cells cooling and solar energy conversion, was also essential. Alternative carbon fiber-reinforced plastic structures were investigated by finite elements using static and modal analyses in the way to compare several design configurations in terms of natural frequencies, deformations, flexural stiffness, torsional stiffness, and heat exchange surfaces. A representative roof section was manufactured and tested for model validation. A significant improvement respect to the pre-existing solar roof was detected. The final configuration was manufactured and installed on the vehicle. Full article

(This article belongs to the Special Issue Composite Materials in Design Processes)

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13 pages, 3322 KiB

Open AccessArticle

Material Characterization for Reliable Resin Transfer Molding Process Simulation

by Maria Pia Falaschetti, Francesco Rondina, Nicola Zavatta, Lisa Gragnani, Martina Gironi, Enrico Troiani and Lorenzo Donati

Appl. Sci. 2020, 10(5), 1814; https://doi.org/10.3390/app10051814 - 06 Mar 2020

Cited by 7 | Viewed by 3626

Abstract

Resin transfer molding (RTM) technologies are widely used in automotive, marine, and aerospace applications. The need to evaluate the impact of design and production critical choices, also in terms of final costs, leads to the wider use of numerical simulation in the preliminary [...] Read more.

Resin transfer molding (RTM) technologies are widely used in automotive, marine, and aerospace applications. The need to evaluate the impact of design and production critical choices, also in terms of final costs, leads to the wider use of numerical simulation in the preliminary phase of component development. The main issue for accurate RTM analysis is the reliable characterization of the involved materials. The aim of this paper is to present a validated methodology for material characterization to be implemented and introduce data elaboration in the ESI PAM-RTM software. Experimental campaigns for reinforcement permeabilities and resin viscosity measurement are presented and discussed. Finally, the obtained data are implemented in the software and then compared to experimental results in order to validate the described methodology. Full article

(This article belongs to the Special Issue Composite Materials in Design Processes)

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16 pages, 6034 KiB

Open AccessArticle

An Analytical Model for the Tension-Shear Coupling of Woven Fabrics with Different Weave Patterns under Large Shear Deformation

by Yanchao Wang, Weizhao Zhang, Huaqing Ren, Zhengming Huang, Furong Geng, Yongxiang Li and Zengyu Zhu

Appl. Sci. 2020, 10(4), 1551; https://doi.org/10.3390/app10041551 - 24 Feb 2020

Cited by 8 | Viewed by 3421

Abstract

It is essential to accurately describe the large shear behavior of woven fabrics in the composite preforming process. An analytical model is proposed to describe the shear behavior of fabrics with different weave patterns, in which tension-shear coupling is considered. The coupling is [...] Read more.

It is essential to accurately describe the large shear behavior of woven fabrics in the composite preforming process. An analytical model is proposed to describe the shear behavior of fabrics with different weave patterns, in which tension-shear coupling is considered. The coupling is involved in two parts, the friction between overlapped yarns and the in-plane transverse compression between two parallel yarns. By introducing the concept of inflection points of a yarn, the model is applicable for fabrics with different weave patterns. The analytical model is validated by biaxial tension-shear experiments. A parametric study is conducted to investigate the effects of external load, yarn geometry, and weave structure on the large shear behavior of fabrics. The developed model can reveal the physical mechanism of tension-shear coupling of woven fabrics. Moreover, the model has a high computational efficiency due to its explicit expressions, thus benefiting the material design process. Full article

(This article belongs to the Special Issue Composite Materials in Design Processes)

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14 pages, 13035 KiB

Open AccessArticle

Repair Performance of Self-Healing Microcapsule/Epoxy Resin Insulating Composite to Physical Damage

by Youyuan Wang, Yudong Li, Zhanxi Zhang, Haisen Zhao and Yanfang Zhang

Appl. Sci. 2019, 9(19), 4098; https://doi.org/10.3390/app9194098 - 01 Oct 2019

Cited by 19 | Viewed by 2594

Abstract

Minor physical damage can reduce the insulation performance of epoxy resin, which seriously threatens the reliability of electrical equipment. In this paper, the epoxy resin insulating composite was prepared by a microcapsule system to achieve its self-healing goal. The repair performance to physical [...] Read more.

Minor physical damage can reduce the insulation performance of epoxy resin, which seriously threatens the reliability of electrical equipment. In this paper, the epoxy resin insulating composite was prepared by a microcapsule system to achieve its self-healing goal. The repair performance to physical damage was analyzed by the tests of scratch, cross-section damage, electric tree, and breakdown strength. The results show that compared with pure epoxy resin, the composite has the obvious self-healing performance. For mechanical damage, the maximum repair rate of physical structure is 100%, and the breakdown strength can be restored to 83% of the original state. For electrical damage, microcapsule can not only attract the electrical tree and inhibit its propagation process, but also repair the tubules of electrical tree effectively. Moreover, the repair rate is fast, which meets the application requirements of epoxy resin insulating material. In addition, the repair behavior is dominated by capillarity and molecular diffusion on the defect surface. Furthermore, the electrical properties of repaired part are greatly affected by the characteristics of damage interface and repair product. In a word, the composite shows better repair performance to physical damage, which is conducive to improving the reliability of electrical insulating materials. Full article

(This article belongs to the Special Issue Composite Materials in Design Processes)

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12 pages, 3481 KiB

Open AccessArticle

Investigation of Electrodeposition External Conditions on Morphology and Texture of Ni/SiCw Composite Coatings

by Liyan Lai, Hongfang Li, Yunna Sun, Guifu Ding, Hong Wang and Zhuoqing Yang

Appl. Sci. 2019, 9(18), 3824; https://doi.org/10.3390/app9183824 - 12 Sep 2019

Cited by 13 | Viewed by 2010

Abstract

Recently, a strategy of synthesizing SiC whisker-reinforced nickel (Ni/SiCw) composites with excellent mechanical properties by electrodeposition has been proposed for exploring its potential applications in micromechanical devices. In this paper, a series of external conditions that affected the content of SiC [...] Read more.

Recently, a strategy of synthesizing SiC whisker-reinforced nickel (Ni/SiCw) composites with excellent mechanical properties by electrodeposition has been proposed for exploring its potential applications in micromechanical devices. In this paper, a series of external conditions that affected the content of SiC whiskers in composite films were studied, such as cathode current density, stirring rate and electrolyte temperature. The experimental results indicated that the optimum morphology was obtained at a stirring speed of 300 rpm, a temperature of 50 °C, and a current density of 18 mA/cm². Additionally, the content of SiC whiskers and textural preference were also investigated by varying its external conditions, and the results demonstrated that the composites with high mass percentage whiskers are more advantageous for electrocrystallization of Ni in the (200) orientation. Finally, the relationship between external conditions and intrinsic morphology, composition and texture of Ni/SiCw composites was revealed, and it provides a constructive approach to fabricate the high-content SiC whiskers of these composites. Full article

(This article belongs to the Special Issue Composite Materials in Design Processes)

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15 pages, 21023 KiB

Open AccessArticle

Optimization of Processing Parameters for Water-Jet-Assisted Laser Etching of Polycrystalline Silicon

by Xuehui Chen, Xiang Li, Chao Wu, Yuping Ma, Yao Zhang, Lei Huang and Wei Liu

Appl. Sci. 2019, 9(9), 1882; https://doi.org/10.3390/app9091882 - 08 May 2019

Cited by 12 | Viewed by 3344

Abstract

Liquid-assisted laser technology is used to etch defect-free materials for high-precision electronics and machinery. This study investigates water-jet-assisted laser etching of polysilicon material. The depths and widths of the etched grooves were investigated for different water-jet incident angles and velocities. To select optimal [...] Read more.

Liquid-assisted laser technology is used to etch defect-free materials for high-precision electronics and machinery. This study investigates water-jet-assisted laser etching of polysilicon material. The depths and widths of the etched grooves were investigated for different water-jet incident angles and velocities. To select optimal parameters for a composite etching processing, the results of many tests must be compared, and at least one set of good processing parameter combinations must be identified. Herein, the influence of different parameters on the processing results is studied using an orthogonal test method. The results demonstrate that the depths and widths of the processing grooves were nearly identical at water-jet angles of 30°and 60°; however, the 60° incidence conferred a slight advantage over 30° incidence. The section taper, section depth, and surface topography were optimized at a water-jet velocity of 24-m/s, 1.1-ms laser pulse width, 40-Hz frequency, and 180-A current. Under these conditions, the section taper and groove depth were 1.2° and 1.88 mm, respectively. The groove surfaces exhibited no splitting, slagging, or other defects, and no recast layers were visible. Full article

(This article belongs to the Special Issue Composite Materials in Design Processes)

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