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Roberto Palazzetti - One of the best experts on this subject based on the ideXlab platform.

  • the effect of thickness of nylon 6 6 nanofibrous mat on modes i ii fracture mechanics of ud and woven composite laminates
    Composite Structures, 2016
    Co-Authors: T M Brugo, Roberto Palazzetti
    Abstract:

    This paper presents an experimental investigation on epoxy resin-carbon bers composites interleaved with Nylon 6,6 nanobers. In particular, the paper focuses on the eect of the thickness of the nanoreinforce into two types of laminae: unidirectional (UD) and plain wave (PW). The eectiveness of the nanoreinforce has been addressed by comparing critical and propagation energy release rates, calculated by testing samples under Mode I and Mode II fracture mechanic loads. Experiments show a general improvement in delamination resistance when the nanobers are interleaved. Nevertheless slightly dierent behaviour has been found between the two types of lamina: micrographs of crack paths have been used to explain the reinforce mechanisms and such dierences, suggest- ing a strong interaction between the nature of the fabric and the thickness of the nanointerlayer.

  • influence of electrospun nanofibers on the interlaminar properties of unidirectional epoxy resin glass fiber composite laminates
    Journal of Reinforced Plastics and Composites, 2015
    Co-Authors: H. Saghafi, Roberto Palazzetti, Andrea Zucchelli, Giangiacomo Minak
    Abstract:

    Nylon 6,6 nanofibers were interleaved in the mid-plane of glass fiber/epoxy matrix composite laminates for Mode I and II fracture mechanic tests. The present study investigates the effect of the nanofibers on the laminates' mechanical response. Results showed that Nylon 6,6 nanofibers improved specimen's fracture mechanic behavior: the initial energy release rates GIC and GIIC increased 62% and 109%, respectively, when nanofibrous interlayer was used. Scanning electron microscope micrographs showed that nanofiber bridging mechanism enhances performances of the nanomodified specimens, still able to link the layers when the matrix is broken.

  • Influence of electrospun nanofibers on the interlaminar properties of unidirectional epoxy resin/glass fiber composite laminates
    Journal of Reinforced Plastics and Composites, 2015
    Co-Authors: H. Saghafi, Roberto Palazzetti, Andrea Zucchelli, Giangiacomo Minak
    Abstract:

    Nylon 6,6 nanofibers were interleaved in the mid-plane of glass fiber/epoxy matrix composite laminates for Mode I and II fracture mechanic tests. The present study investigates the effect of the nanofibers on the laminates' mechanical response. Results showed that Nylon 6,6 nanofibers improved specimen's fracture mechanic behavior: the initial energy release rates GIC and GIIC increased 62% and 109%, respectively, when nanofibrous interlayer was used. Scanning electron microscope micrographs showed that nanofiber bridging mechanism enhances performances of the nanomodified specimens, still able to link the layers when the matrix is broken.

  • the effect of interleaved composite nanofibrous mats on delamination behavior of polymeric composite materials
    Composite Structures, 2014
    Co-Authors: H. Saghafi, Andrea Zucchelli, Giangiacomo Minak, Roberto Palazzetti
    Abstract:

    In this study the effect of interleaved nanofiber on mode I and mode II fracture response of composite laminates is considered. For this aim, electrospun Nylon 6,6 and poly-caprolactone (PCL) nanofibers and their combination are put in the mid-plane of unidirectional glass/epoxy laminates, which are then subjected to double cantilever beam (DCB) and end notched flexure (ENF) fracture tests. Results showed that PCL nanofibers could improve modes I and II energy release rate (GI and GII) almost equally with 25% and 24% increase. Influence of Nylon 6,6 nanofiber is mostly on mode II loading with 68% enhancement, while its effect on mode I is negligible (4.5% increase). It is also shown that combination of these two kinds of nanofibers lead to 21% and 56% increase in GI and GII, respectively which are between the results of the individual nanofibers.

  • influence of geometrical features of electrospun nylon 6 6 interleave on the cfrp laminates mechanical properties
    Polymer Composites, 2014
    Co-Authors: Roberto Palazzetti, Andrea Zucchelli
    Abstract:

    Twenty plies, woven carbon fiber/epoxy matrix, virgin, and Nylon 6,6 electrospun nanofiber interleaved composite laminate beams are tested under Modes I and II fracture mechanic to assess the effect of nanointerleave on the global behavior of the laminate. Aim of the work is to study the effect of geometrical features of the nanoreinforce on the mechanical response of a laminate subjected to fracture mechanic loads. Nanofiber orientation, nanolayer thickness, and nanofiber diameter have been considered. From the experiments, mechanical parameters have been extracted and used to compare the configurations. The work highlights the importance of an accurate choice of the nanointerleave and showed that thick interleaves may weaken the interface if a high number of voids is left after the curing process, the smaller is the fiber diameter the higher is the energy absorbing capability of the specimens, and that fiber orientation has different effect depending on the loading mode.

Andrea Zucchelli - One of the best experts on this subject based on the ideXlab platform.

  • low velocity impact damage assessment of glare fiber metal laminates interleaved by nylon 6 6 nanofiber mats
    Composite Structures, 2017
    Co-Authors: Hamed Zarei, Tommaso Maria Brugo, Juri Belcari, H Bisadi, Giangiacomo Minak, Andrea Zucchelli
    Abstract:

    Abstract GLARE is one of the most popular hybrid composite materials used in the aerospace structures which may be exposed to impact. Although the impact damage resistance of GLARE is better than its individual constituents i.e. aluminum and glass/epoxy composites, the poor strength of the lamina’s interfaces causes failure modes such as delamination and debonding. Hence, the present research aims to increase the impact resistance of GLARE by nanofiber interleaving. Nylon 6,6 nanofiber non-woven mats were fabricated by electrospinning technique and interleaved between the aluminum sheets and the glass fiber prepreg plies. Low velocity impact tests were performed on the nano-reinforced and the virgin laminates at 4 different impact energy levels: 6, 12, 18 and 32 J. The damage was evaluated by micrograph analysis of the impacted zone and visual inspection of the outer surface of the non-impacted side. Impact tests showed similar dynamic response for both laminate types. However, micrograph analysis revealed lower debonding length of the aluminum/glass fiber interfaces reinforced by Nylon 6,6 nanofibers. Moreover, the analysis of the outer surface showed that Nylon 6,6 nanofiber interleaving can reduce the damage area of GLARE by up to 62%.

  • influence of electrospun nanofibers on the interlaminar properties of unidirectional epoxy resin glass fiber composite laminates
    Journal of Reinforced Plastics and Composites, 2015
    Co-Authors: H. Saghafi, Roberto Palazzetti, Andrea Zucchelli, Giangiacomo Minak
    Abstract:

    Nylon 6,6 nanofibers were interleaved in the mid-plane of glass fiber/epoxy matrix composite laminates for Mode I and II fracture mechanic tests. The present study investigates the effect of the nanofibers on the laminates' mechanical response. Results showed that Nylon 6,6 nanofibers improved specimen's fracture mechanic behavior: the initial energy release rates GIC and GIIC increased 62% and 109%, respectively, when nanofibrous interlayer was used. Scanning electron microscope micrographs showed that nanofiber bridging mechanism enhances performances of the nanomodified specimens, still able to link the layers when the matrix is broken.

  • Influence of electrospun nanofibers on the interlaminar properties of unidirectional epoxy resin/glass fiber composite laminates
    Journal of Reinforced Plastics and Composites, 2015
    Co-Authors: H. Saghafi, Roberto Palazzetti, Andrea Zucchelli, Giangiacomo Minak
    Abstract:

    Nylon 6,6 nanofibers were interleaved in the mid-plane of glass fiber/epoxy matrix composite laminates for Mode I and II fracture mechanic tests. The present study investigates the effect of the nanofibers on the laminates' mechanical response. Results showed that Nylon 6,6 nanofibers improved specimen's fracture mechanic behavior: the initial energy release rates GIC and GIIC increased 62% and 109%, respectively, when nanofibrous interlayer was used. Scanning electron microscope micrographs showed that nanofiber bridging mechanism enhances performances of the nanomodified specimens, still able to link the layers when the matrix is broken.

  • the effect of interleaved composite nanofibrous mats on delamination behavior of polymeric composite materials
    Composite Structures, 2014
    Co-Authors: H. Saghafi, Andrea Zucchelli, Giangiacomo Minak, Roberto Palazzetti
    Abstract:

    In this study the effect of interleaved nanofiber on mode I and mode II fracture response of composite laminates is considered. For this aim, electrospun Nylon 6,6 and poly-caprolactone (PCL) nanofibers and their combination are put in the mid-plane of unidirectional glass/epoxy laminates, which are then subjected to double cantilever beam (DCB) and end notched flexure (ENF) fracture tests. Results showed that PCL nanofibers could improve modes I and II energy release rate (GI and GII) almost equally with 25% and 24% increase. Influence of Nylon 6,6 nanofiber is mostly on mode II loading with 68% enhancement, while its effect on mode I is negligible (4.5% increase). It is also shown that combination of these two kinds of nanofibers lead to 21% and 56% increase in GI and GII, respectively which are between the results of the individual nanofibers.

  • influence of geometrical features of electrospun nylon 6 6 interleave on the cfrp laminates mechanical properties
    Polymer Composites, 2014
    Co-Authors: Roberto Palazzetti, Andrea Zucchelli
    Abstract:

    Twenty plies, woven carbon fiber/epoxy matrix, virgin, and Nylon 6,6 electrospun nanofiber interleaved composite laminate beams are tested under Modes I and II fracture mechanic to assess the effect of nanointerleave on the global behavior of the laminate. Aim of the work is to study the effect of geometrical features of the nanoreinforce on the mechanical response of a laminate subjected to fracture mechanic loads. Nanofiber orientation, nanolayer thickness, and nanofiber diameter have been considered. From the experiments, mechanical parameters have been extracted and used to compare the configurations. The work highlights the importance of an accurate choice of the nanointerleave and showed that thick interleaves may weaken the interface if a high number of voids is left after the curing process, the smaller is the fiber diameter the higher is the energy absorbing capability of the specimens, and that fiber orientation has different effect depending on the loading mode.

S Ramakrishna - One of the best experts on this subject based on the ideXlab platform.

  • influence of electrospun nylon 6 6 nanofibrous mats on the interlaminar properties of gr epoxy composite laminates
    Composite Structures, 2012
    Co-Authors: Roberto Palazzetti, Andrea Zucchelli, Giangiacomo Minak, Chiara Gualandi, Maria Letizia Focarete, Lorenzo Donati, S Ramakrishna
    Abstract:

    Abstract The present work aims at investigating the influence of electrospun Nylon 6,6 nanofibrous mat to interlaminar strength. Mode I and the Mode II fracture mechanics of virgin and nanomodified laminates are investigated. Nanomodified laminates are fabricated by interleaving an electrospun nanofibrous mats in laminate mid-plane. Double Cantilever Beam (DCB) and End Notched Flexure (ENF) tests are performed on both virgin and nanomodified configuration. Results show that electrospun nanofibrous mat is able to increase by 23.2% the mechanical energy absorbing capability and by about 5% the G IC . ENF tests reveal that the nanofibrous mats contribute to improve the maximum stress before the material crisis (6.5% of increment) and a measurable increment of (8.1%) the maximum mechanical energy that can be absorbed by the material during the crack propagation is registered. The acoustic emission (AE) technique is used to monitor both DCB and ENF tests. The AE information highlight that the nanofibrous mats mitigate the interlaminar matrix failure on both the fracture modes.

Giangiacomo Minak - One of the best experts on this subject based on the ideXlab platform.

  • low velocity impact damage assessment of glare fiber metal laminates interleaved by nylon 6 6 nanofiber mats
    Composite Structures, 2017
    Co-Authors: Hamed Zarei, Tommaso Maria Brugo, Juri Belcari, H Bisadi, Giangiacomo Minak, Andrea Zucchelli
    Abstract:

    Abstract GLARE is one of the most popular hybrid composite materials used in the aerospace structures which may be exposed to impact. Although the impact damage resistance of GLARE is better than its individual constituents i.e. aluminum and glass/epoxy composites, the poor strength of the lamina’s interfaces causes failure modes such as delamination and debonding. Hence, the present research aims to increase the impact resistance of GLARE by nanofiber interleaving. Nylon 6,6 nanofiber non-woven mats were fabricated by electrospinning technique and interleaved between the aluminum sheets and the glass fiber prepreg plies. Low velocity impact tests were performed on the nano-reinforced and the virgin laminates at 4 different impact energy levels: 6, 12, 18 and 32 J. The damage was evaluated by micrograph analysis of the impacted zone and visual inspection of the outer surface of the non-impacted side. Impact tests showed similar dynamic response for both laminate types. However, micrograph analysis revealed lower debonding length of the aluminum/glass fiber interfaces reinforced by Nylon 6,6 nanofibers. Moreover, the analysis of the outer surface showed that Nylon 6,6 nanofiber interleaving can reduce the damage area of GLARE by up to 62%.

  • influence of electrospun nanofibers on the interlaminar properties of unidirectional epoxy resin glass fiber composite laminates
    Journal of Reinforced Plastics and Composites, 2015
    Co-Authors: H. Saghafi, Roberto Palazzetti, Andrea Zucchelli, Giangiacomo Minak
    Abstract:

    Nylon 6,6 nanofibers were interleaved in the mid-plane of glass fiber/epoxy matrix composite laminates for Mode I and II fracture mechanic tests. The present study investigates the effect of the nanofibers on the laminates' mechanical response. Results showed that Nylon 6,6 nanofibers improved specimen's fracture mechanic behavior: the initial energy release rates GIC and GIIC increased 62% and 109%, respectively, when nanofibrous interlayer was used. Scanning electron microscope micrographs showed that nanofiber bridging mechanism enhances performances of the nanomodified specimens, still able to link the layers when the matrix is broken.

  • Influence of electrospun nanofibers on the interlaminar properties of unidirectional epoxy resin/glass fiber composite laminates
    Journal of Reinforced Plastics and Composites, 2015
    Co-Authors: H. Saghafi, Roberto Palazzetti, Andrea Zucchelli, Giangiacomo Minak
    Abstract:

    Nylon 6,6 nanofibers were interleaved in the mid-plane of glass fiber/epoxy matrix composite laminates for Mode I and II fracture mechanic tests. The present study investigates the effect of the nanofibers on the laminates' mechanical response. Results showed that Nylon 6,6 nanofibers improved specimen's fracture mechanic behavior: the initial energy release rates GIC and GIIC increased 62% and 109%, respectively, when nanofibrous interlayer was used. Scanning electron microscope micrographs showed that nanofiber bridging mechanism enhances performances of the nanomodified specimens, still able to link the layers when the matrix is broken.

  • the effect of interleaved composite nanofibrous mats on delamination behavior of polymeric composite materials
    Composite Structures, 2014
    Co-Authors: H. Saghafi, Andrea Zucchelli, Giangiacomo Minak, Roberto Palazzetti
    Abstract:

    In this study the effect of interleaved nanofiber on mode I and mode II fracture response of composite laminates is considered. For this aim, electrospun Nylon 6,6 and poly-caprolactone (PCL) nanofibers and their combination are put in the mid-plane of unidirectional glass/epoxy laminates, which are then subjected to double cantilever beam (DCB) and end notched flexure (ENF) fracture tests. Results showed that PCL nanofibers could improve modes I and II energy release rate (GI and GII) almost equally with 25% and 24% increase. Influence of Nylon 6,6 nanofiber is mostly on mode II loading with 68% enhancement, while its effect on mode I is negligible (4.5% increase). It is also shown that combination of these two kinds of nanofibers lead to 21% and 56% increase in GI and GII, respectively which are between the results of the individual nanofibers.

  • influence of electrospun nylon 6 6 nanofibrous mats on the interlaminar properties of gr epoxy composite laminates
    Composite Structures, 2012
    Co-Authors: Roberto Palazzetti, Andrea Zucchelli, Giangiacomo Minak, Chiara Gualandi, Maria Letizia Focarete, Lorenzo Donati, S Ramakrishna
    Abstract:

    Abstract The present work aims at investigating the influence of electrospun Nylon 6,6 nanofibrous mat to interlaminar strength. Mode I and the Mode II fracture mechanics of virgin and nanomodified laminates are investigated. Nanomodified laminates are fabricated by interleaving an electrospun nanofibrous mats in laminate mid-plane. Double Cantilever Beam (DCB) and End Notched Flexure (ENF) tests are performed on both virgin and nanomodified configuration. Results show that electrospun nanofibrous mat is able to increase by 23.2% the mechanical energy absorbing capability and by about 5% the G IC . ENF tests reveal that the nanofibrous mats contribute to improve the maximum stress before the material crisis (6.5% of increment) and a measurable increment of (8.1%) the maximum mechanical energy that can be absorbed by the material during the crack propagation is registered. The acoustic emission (AE) technique is used to monitor both DCB and ENF tests. The AE information highlight that the nanofibrous mats mitigate the interlaminar matrix failure on both the fracture modes.

H. Saghafi - One of the best experts on this subject based on the ideXlab platform.

  • Considering damages to open-holed composite laminates modified by nanofibers under the three-point bending test
    Polymer Testing, 2018
    Co-Authors: A. Gholizadeh, H. Saghafi, M. Ahmadi Najafabadi, Reza Mohammadi
    Abstract:

    Abstract Nowadays, many components are made of composite laminates assembly by bolted or riveted joints. Thus, the drilling of laminates is a usual machining operation in many industries. Due to the stress concentration around the hole, different damage modes can occur during the service. In this study, the effect of interleaving Nylon 66 nanofibers between glass/epoxy laminate on decreasing damage under the three-point bending test is considered. The results showed that applying nanofibers caused a 57% decrease in the delaminated area. On the other hand, the Acoustic Emission (AE) technique was used to consider the effect of Nylon 66 nanofiber on other damage modes, matrix cracking, fiber/matrix debonding, and fiber breakage. AE signals were analyzed with three different methods, the outcomes showing that these damages significantly decreased.

  • influence of electrospun nanofibers on the interlaminar properties of unidirectional epoxy resin glass fiber composite laminates
    Journal of Reinforced Plastics and Composites, 2015
    Co-Authors: H. Saghafi, Roberto Palazzetti, Andrea Zucchelli, Giangiacomo Minak
    Abstract:

    Nylon 6,6 nanofibers were interleaved in the mid-plane of glass fiber/epoxy matrix composite laminates for Mode I and II fracture mechanic tests. The present study investigates the effect of the nanofibers on the laminates' mechanical response. Results showed that Nylon 6,6 nanofibers improved specimen's fracture mechanic behavior: the initial energy release rates GIC and GIIC increased 62% and 109%, respectively, when nanofibrous interlayer was used. Scanning electron microscope micrographs showed that nanofiber bridging mechanism enhances performances of the nanomodified specimens, still able to link the layers when the matrix is broken.

  • Influence of electrospun nanofibers on the interlaminar properties of unidirectional epoxy resin/glass fiber composite laminates
    Journal of Reinforced Plastics and Composites, 2015
    Co-Authors: H. Saghafi, Roberto Palazzetti, Andrea Zucchelli, Giangiacomo Minak
    Abstract:

    Nylon 6,6 nanofibers were interleaved in the mid-plane of glass fiber/epoxy matrix composite laminates for Mode I and II fracture mechanic tests. The present study investigates the effect of the nanofibers on the laminates' mechanical response. Results showed that Nylon 6,6 nanofibers improved specimen's fracture mechanic behavior: the initial energy release rates GIC and GIIC increased 62% and 109%, respectively, when nanofibrous interlayer was used. Scanning electron microscope micrographs showed that nanofiber bridging mechanism enhances performances of the nanomodified specimens, still able to link the layers when the matrix is broken.

  • the effect of interleaved composite nanofibrous mats on delamination behavior of polymeric composite materials
    Composite Structures, 2014
    Co-Authors: H. Saghafi, Andrea Zucchelli, Giangiacomo Minak, Roberto Palazzetti
    Abstract:

    In this study the effect of interleaved nanofiber on mode I and mode II fracture response of composite laminates is considered. For this aim, electrospun Nylon 6,6 and poly-caprolactone (PCL) nanofibers and their combination are put in the mid-plane of unidirectional glass/epoxy laminates, which are then subjected to double cantilever beam (DCB) and end notched flexure (ENF) fracture tests. Results showed that PCL nanofibers could improve modes I and II energy release rate (GI and GII) almost equally with 25% and 24% increase. Influence of Nylon 6,6 nanofiber is mostly on mode II loading with 68% enhancement, while its effect on mode I is negligible (4.5% increase). It is also shown that combination of these two kinds of nanofibers lead to 21% and 56% increase in GI and GII, respectively which are between the results of the individual nanofibers.