Pub Date : 2022-11-01DOI: 10.1080/20550340.2022.2143105
D. Zebrine, Mark Anders, S. Nutt
Abstract In this work, we investigate the use of discontinuous resin films in prepregs (semipregs) combined with a semi-permeable (air-permeable, resin-impermeable) release film intended to allow through-thickness air evacuation while simultaneously restricting resin loss. In situ measurements of resin pressure were deployed to test the hypothesis that resin pressure was maintained during prepreg cure when using a semi-permeable release film. Concurrently, visualization of the tool-side surface during cure revealed efficient evacuation of entrapped air. Porosity in laminates formed at high temperatures when using resin-permeable consumables, but did not form when using resin-impermeable (semi-permeable) consumables. To confirm that the observed void growth behavior was due to a loss in resin pressure, experiments were conducted to measure resin pressure during cure with both resin-permeable and resin-impermeable (semi-permeable) consumables. In both cases, resin pressure peaked before decreasing, a finding attributed to resin flowing to fill dry regions in the fabric, present by design. The drop in resin pressure, however, was greater in magnitude and longer in duration when using resin-permeable edge and bag-side surface boundaries, indicating that the observed void growth at elevated temperature was caused by a loss in resin pressure. Use of a semi-permeable membrane was effective in retaining resin content and mitigating such porosity. Graphical Abstract
{"title":"Mitigating void growth in out-of-autoclave prepreg processing using a semi-permeable membrane to maintain resin pressure","authors":"D. Zebrine, Mark Anders, S. Nutt","doi":"10.1080/20550340.2022.2143105","DOIUrl":"https://doi.org/10.1080/20550340.2022.2143105","url":null,"abstract":"Abstract In this work, we investigate the use of discontinuous resin films in prepregs (semipregs) combined with a semi-permeable (air-permeable, resin-impermeable) release film intended to allow through-thickness air evacuation while simultaneously restricting resin loss. In situ measurements of resin pressure were deployed to test the hypothesis that resin pressure was maintained during prepreg cure when using a semi-permeable release film. Concurrently, visualization of the tool-side surface during cure revealed efficient evacuation of entrapped air. Porosity in laminates formed at high temperatures when using resin-permeable consumables, but did not form when using resin-impermeable (semi-permeable) consumables. To confirm that the observed void growth behavior was due to a loss in resin pressure, experiments were conducted to measure resin pressure during cure with both resin-permeable and resin-impermeable (semi-permeable) consumables. In both cases, resin pressure peaked before decreasing, a finding attributed to resin flowing to fill dry regions in the fabric, present by design. The drop in resin pressure, however, was greater in magnitude and longer in duration when using resin-permeable edge and bag-side surface boundaries, indicating that the observed void growth at elevated temperature was caused by a loss in resin pressure. Use of a semi-permeable membrane was effective in retaining resin content and mitigating such porosity. Graphical Abstract","PeriodicalId":7243,"journal":{"name":"Advanced Manufacturing: Polymer & Composites Science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84820931","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-09-19DOI: 10.1080/20550340.2022.2122119
K. Kotzur, G. Doll, P. Hermann
Abstract In this study, a brazing method for carbon fiber-reinforced poly ether ketone ketone (CF-PEKK) is developed that allows welding below the melting temperature of the single components. During the manufacturing of CF-PEKK laminates, a pseudo-amorphous PEKK film is consolidated to its surface which acts as interlayer polymer during subsequent joining (brazing). Five different brazing temperatures, determined from thermal analysis of the material, are characterized for their weld quality mechanically, analytically, and through ultrasonic testing. Microanalytically Scanning Electron Microscope (SEM) investigations focus on the morphology of the weld zone in order to evaluate the diffusion processes at the interfaces. Compared to Differential Scanning Calorimetry measurements, the SEM investigations offer a basic understanding of the welded process and its influence on the welding properties. A welding temperature of 60 °C below the processing temperature of CF-PEKK laminates (380 °C) is shown to yield a welding factor of 0.93. Furthermore, based on the SEM investigation, it is possible to derive more promising improvement measures for the brazing method. Graphical Abstract
{"title":"Analysis and development of a brazing method to weld carbon fiber-reinforced poly ether ketone ketone with amorphous PEKK","authors":"K. Kotzur, G. Doll, P. Hermann","doi":"10.1080/20550340.2022.2122119","DOIUrl":"https://doi.org/10.1080/20550340.2022.2122119","url":null,"abstract":"Abstract In this study, a brazing method for carbon fiber-reinforced poly ether ketone ketone (CF-PEKK) is developed that allows welding below the melting temperature of the single components. During the manufacturing of CF-PEKK laminates, a pseudo-amorphous PEKK film is consolidated to its surface which acts as interlayer polymer during subsequent joining (brazing). Five different brazing temperatures, determined from thermal analysis of the material, are characterized for their weld quality mechanically, analytically, and through ultrasonic testing. Microanalytically Scanning Electron Microscope (SEM) investigations focus on the morphology of the weld zone in order to evaluate the diffusion processes at the interfaces. Compared to Differential Scanning Calorimetry measurements, the SEM investigations offer a basic understanding of the welded process and its influence on the welding properties. A welding temperature of 60 °C below the processing temperature of CF-PEKK laminates (380 °C) is shown to yield a welding factor of 0.93. Furthermore, based on the SEM investigation, it is possible to derive more promising improvement measures for the brazing method. Graphical Abstract","PeriodicalId":7243,"journal":{"name":"Advanced Manufacturing: Polymer & Composites Science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77542110","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-08-08DOI: 10.1080/20550340.2022.2106347
D. Bender, T. Centea, S. Nutt
Abstract To address the need for high-quality in-field repair of composite structures, a vacuum-bag-only (VBO) prepreg was designed, produced, and evaluated. The prepreg featured semi-preg formatting and a room-temperature-stable resin. The format provided a multitude of pathways with much shorter breathe-out distances relative to conventional, edge-breathing VBO prepregs, and thus enhanced through-thickness air permeability. A custom-built scarfed repair tool with an in-situ observation window was designed and employed to analyze the cure process during a repair. Microstructural quality, interlaminar shear strength, and glass transition temperature of semi-preg panels were compared to wet-laid epoxy panels processed with double vacuum debulking (DVD). The semi-preg formatting effectively reduced porosity for in-field scarf panels, and when used with the new material system, presents a viable alternative to DVD and wet layup. GRAPHICAL ABSTRACT
{"title":"In-situ analysis of cocured scarf patch repairs","authors":"D. Bender, T. Centea, S. Nutt","doi":"10.1080/20550340.2022.2106347","DOIUrl":"https://doi.org/10.1080/20550340.2022.2106347","url":null,"abstract":"Abstract To address the need for high-quality in-field repair of composite structures, a vacuum-bag-only (VBO) prepreg was designed, produced, and evaluated. The prepreg featured semi-preg formatting and a room-temperature-stable resin. The format provided a multitude of pathways with much shorter breathe-out distances relative to conventional, edge-breathing VBO prepregs, and thus enhanced through-thickness air permeability. A custom-built scarfed repair tool with an in-situ observation window was designed and employed to analyze the cure process during a repair. Microstructural quality, interlaminar shear strength, and glass transition temperature of semi-preg panels were compared to wet-laid epoxy panels processed with double vacuum debulking (DVD). The semi-preg formatting effectively reduced porosity for in-field scarf panels, and when used with the new material system, presents a viable alternative to DVD and wet layup. GRAPHICAL ABSTRACT","PeriodicalId":7243,"journal":{"name":"Advanced Manufacturing: Polymer & Composites Science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89779536","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-05-31DOI: 10.1080/20550340.2022.2077277
M. Salmins, P. Mitschang
Abstract Thermoplastic foams allow manufacturing of lightweight parts with good thermal and acoustic insulation properties. To increase the mechanical properties without changing the part weight, these foams can be transformed into structural foams by a newly developed two-step isochoric and isothermal hot press process. Structural foams consist of a low-density foam core and two high-density polymer skins. The production of a polymer skin on the surface of a foam was realized in a hot press process by heating one tool half to process temperatures above glass transition temperature of the amorphous polymer. To manufacture polymer skins on both sides of the foam, it is necessary to turn the foam upside down and repeat the procedure. Structural foams were manufactured with two different polymer foams with different cell structures and densities. Optical analysis of microsections was used to investigate the formation of the polymer skins and the change in foam structure. This study investigates the applicability of an empirical relationship between part densities and bending properties. It was found, that knowledge about the part density alone is not sufficient for the prediction of the bending properties, because the foam structure (e.g. open or closed foam cells) has a considerable impact on the foam properties. Graphical Abstract
{"title":"Bending properties of structural foams manufactured in a hot press process","authors":"M. Salmins, P. Mitschang","doi":"10.1080/20550340.2022.2077277","DOIUrl":"https://doi.org/10.1080/20550340.2022.2077277","url":null,"abstract":"Abstract Thermoplastic foams allow manufacturing of lightweight parts with good thermal and acoustic insulation properties. To increase the mechanical properties without changing the part weight, these foams can be transformed into structural foams by a newly developed two-step isochoric and isothermal hot press process. Structural foams consist of a low-density foam core and two high-density polymer skins. The production of a polymer skin on the surface of a foam was realized in a hot press process by heating one tool half to process temperatures above glass transition temperature of the amorphous polymer. To manufacture polymer skins on both sides of the foam, it is necessary to turn the foam upside down and repeat the procedure. Structural foams were manufactured with two different polymer foams with different cell structures and densities. Optical analysis of microsections was used to investigate the formation of the polymer skins and the change in foam structure. This study investigates the applicability of an empirical relationship between part densities and bending properties. It was found, that knowledge about the part density alone is not sufficient for the prediction of the bending properties, because the foam structure (e.g. open or closed foam cells) has a considerable impact on the foam properties. Graphical Abstract","PeriodicalId":7243,"journal":{"name":"Advanced Manufacturing: Polymer & Composites Science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76304179","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-05-29DOI: 10.1080/20550340.2022.2077890
D. Zebrine, Navid Niknafs Kermani, P. Šimáček, T. Cender, S. Advani, S. Nutt
Abstract Predictive models describing the co-cure process of honeycomb sandwich structures can increase manufacturing efficiency of aerospace structures by offering rapid, low-cost screening of viable combinations of material and process parameters. Honeycomb sandwich structures are co-cured to bond partially-cured thermoset prepreg facesheets with an adhesive layer to the core structure, during which multiple physical phenomena occur simultaneously. A physics-based predictive tool is developed to simulate this process by integration of sub-models for the adhesive bond-line fillet shape, facesheet consolidation process, and the porosity development within the bond-line, which, due to the coupling effects, is highly dependent on the former two phenomena. In this work, the experimental validation of both the individual sub-models and an integrated model for bond-line porosity is conducted. Despite the stochastic behavior of the co-cure process, the models successfully capture trends in adhesive fillet shape and the bond-line porosity, demonstrating their utility as tools for process screening to maximize the quality of co-cured parts. GRAPHICAL ABSTRACT
{"title":"Experimental validation of co-cure process of honeycomb sandwich structures simulation: adhesive fillet shape and bond-line porosity","authors":"D. Zebrine, Navid Niknafs Kermani, P. Šimáček, T. Cender, S. Advani, S. Nutt","doi":"10.1080/20550340.2022.2077890","DOIUrl":"https://doi.org/10.1080/20550340.2022.2077890","url":null,"abstract":"Abstract Predictive models describing the co-cure process of honeycomb sandwich structures can increase manufacturing efficiency of aerospace structures by offering rapid, low-cost screening of viable combinations of material and process parameters. Honeycomb sandwich structures are co-cured to bond partially-cured thermoset prepreg facesheets with an adhesive layer to the core structure, during which multiple physical phenomena occur simultaneously. A physics-based predictive tool is developed to simulate this process by integration of sub-models for the adhesive bond-line fillet shape, facesheet consolidation process, and the porosity development within the bond-line, which, due to the coupling effects, is highly dependent on the former two phenomena. In this work, the experimental validation of both the individual sub-models and an integrated model for bond-line porosity is conducted. Despite the stochastic behavior of the co-cure process, the models successfully capture trends in adhesive fillet shape and the bond-line porosity, demonstrating their utility as tools for process screening to maximize the quality of co-cured parts. GRAPHICAL ABSTRACT","PeriodicalId":7243,"journal":{"name":"Advanced Manufacturing: Polymer & Composites Science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-05-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90754631","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-04-03DOI: 10.1080/20550340.2022.2064069
Margarita Etchegaray Bello, R. Engelhardt, D. Bublitz, K. Drechsler
Abstract During its consolidation, uncured thermoset prepreg is exposed to cyclic loading conditions throughout the various stages of the process chain, including material deposition, vacuum debulking, and curing. One significant challenge involves understanding multilayer prepreg tapes’ compaction behavior to optimise the process’s efficiency and improve the final laminate properties. Automated Fibre Placement (AFP) is a suitable process for the automated manufacture of high-quality aerospace structures with reproducible properties. The compaction analysis offers the potential to reduce subsequent steps during other related compaction stages in the process, such as vacuum debulking or autoclave curing. A cyclic compaction-recovery test that approximates AFP conditions was performed with a rheometer. An experimental analysis was conducted into different parameters’ qualitative influence on uncured multilayer thermoset prepreg samples’ compressibility and their characteristics during load release, using a rheometer on a laboratory scale. The variables manipulated were: temperature, pressure, the number of plies, ply configuration, and tape type. The results showed that temperature strongly influenced the thickness reduction until a compaction threshold was approached, and the pressure level’s effect on the final thickness depended greatly on the temperature. The thickness reduction was greater at higher temperatures until a compaction threshold was observed. Further investigations are recommended to gain insight into the flow mechanism within the sample and its void content after compaction to use the data to optimise the parameters. GRAPHICAL ABSTRACT
{"title":"Lab-scale experimental analysis of the cyclic compaction-recovery characteristics of uncured thermoset prepreg","authors":"Margarita Etchegaray Bello, R. Engelhardt, D. Bublitz, K. Drechsler","doi":"10.1080/20550340.2022.2064069","DOIUrl":"https://doi.org/10.1080/20550340.2022.2064069","url":null,"abstract":"Abstract During its consolidation, uncured thermoset prepreg is exposed to cyclic loading conditions throughout the various stages of the process chain, including material deposition, vacuum debulking, and curing. One significant challenge involves understanding multilayer prepreg tapes’ compaction behavior to optimise the process’s efficiency and improve the final laminate properties. Automated Fibre Placement (AFP) is a suitable process for the automated manufacture of high-quality aerospace structures with reproducible properties. The compaction analysis offers the potential to reduce subsequent steps during other related compaction stages in the process, such as vacuum debulking or autoclave curing. A cyclic compaction-recovery test that approximates AFP conditions was performed with a rheometer. An experimental analysis was conducted into different parameters’ qualitative influence on uncured multilayer thermoset prepreg samples’ compressibility and their characteristics during load release, using a rheometer on a laboratory scale. The variables manipulated were: temperature, pressure, the number of plies, ply configuration, and tape type. The results showed that temperature strongly influenced the thickness reduction until a compaction threshold was approached, and the pressure level’s effect on the final thickness depended greatly on the temperature. The thickness reduction was greater at higher temperatures until a compaction threshold was observed. Further investigations are recommended to gain insight into the flow mechanism within the sample and its void content after compaction to use the data to optimise the parameters. GRAPHICAL ABSTRACT","PeriodicalId":7243,"journal":{"name":"Advanced Manufacturing: Polymer & Composites Science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73052460","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-04-03DOI: 10.1080/20550340.2022.2057137
J. Barroeta Robles, M. Dubé, P. Hubert, A. Yousefpour
Abstract An extensive review of literature is conducted to present the evolution of the field of repair of thermoplastic composites (TPC’s) from when it was first mentioned in 1980. The TPC materials used today in aerospace structures are introduced along with the existing challenges to repair TPC structures. The three most promising fusion bonding techniques to address these challenges (i.e. induction, resistance, and ultrasonic welding) are explained. The certification authorities have extensive knowledge and data for repair of thermoset polymer matrix composite structures. However, such level of knowledge is highly limited for TPC structures. A lack of robust processes and the overall lack of data on TPC’s when compared to their thermoset counterparts are challenges that need to be addressed to implement TPC materials in aircraft structures. GRAPHICAL ABSTRACT
{"title":"Repair of thermoplastic composites: an overview","authors":"J. Barroeta Robles, M. Dubé, P. Hubert, A. Yousefpour","doi":"10.1080/20550340.2022.2057137","DOIUrl":"https://doi.org/10.1080/20550340.2022.2057137","url":null,"abstract":"Abstract An extensive review of literature is conducted to present the evolution of the field of repair of thermoplastic composites (TPC’s) from when it was first mentioned in 1980. The TPC materials used today in aerospace structures are introduced along with the existing challenges to repair TPC structures. The three most promising fusion bonding techniques to address these challenges (i.e. induction, resistance, and ultrasonic welding) are explained. The certification authorities have extensive knowledge and data for repair of thermoset polymer matrix composite structures. However, such level of knowledge is highly limited for TPC structures. A lack of robust processes and the overall lack of data on TPC’s when compared to their thermoset counterparts are challenges that need to be addressed to implement TPC materials in aircraft structures. GRAPHICAL ABSTRACT","PeriodicalId":7243,"journal":{"name":"Advanced Manufacturing: Polymer & Composites Science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86666351","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-04-03DOI: 10.1080/20550340.2022.2064070
Bjoern Willenbacher, D. May, P. Mitschang
Abstract Out-of-plane impregnation and high levels of injection pressure are key strategies for cycle time reduction in Liquid Composite Molding processes. The combination of these two strategies provides a promising approach for large volume production of automotive components. In this context, a novel test system is presented, which allows the textile reaction characterization to saturated out-of-plane fluid flow at injection pressure levels of up to 200 bar. For any given engineering textile, the resulting out-of-plane permeability and total hydrodynamic compaction can be measured for different combinations of initial fiber volume content, number of layers and injection pressure. Initial tests on a conventional non-crimp fabric show a compaction-induced out-of-plane permeability decrease for pressure levels up to 95 bar, while for pressure levels between 95 and 170 bar the permeability remains constant. In other words above 95 bar, a further increase in pressure directly pays off in terms of increased flow rate. The identification of such processing windows can be very valuable for process design. Graphical Abstract
{"title":"Saturated out-of-plane permeability and deformation metrology of textiles at high levels of injection pressure","authors":"Bjoern Willenbacher, D. May, P. Mitschang","doi":"10.1080/20550340.2022.2064070","DOIUrl":"https://doi.org/10.1080/20550340.2022.2064070","url":null,"abstract":"Abstract Out-of-plane impregnation and high levels of injection pressure are key strategies for cycle time reduction in Liquid Composite Molding processes. The combination of these two strategies provides a promising approach for large volume production of automotive components. In this context, a novel test system is presented, which allows the textile reaction characterization to saturated out-of-plane fluid flow at injection pressure levels of up to 200 bar. For any given engineering textile, the resulting out-of-plane permeability and total hydrodynamic compaction can be measured for different combinations of initial fiber volume content, number of layers and injection pressure. Initial tests on a conventional non-crimp fabric show a compaction-induced out-of-plane permeability decrease for pressure levels up to 95 bar, while for pressure levels between 95 and 170 bar the permeability remains constant. In other words above 95 bar, a further increase in pressure directly pays off in terms of increased flow rate. The identification of such processing windows can be very valuable for process design. Graphical Abstract","PeriodicalId":7243,"journal":{"name":"Advanced Manufacturing: Polymer & Composites Science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91349254","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-04-03DOI: 10.1080/20550340.2022.2056313
D. Zebrine, Elana Wadhwani, S. Nutt
Abstract Co-cure of honeycomb core sandwich structures combines the consolidation of composite prepreg facesheets with bonding of facesheets to a low-density core in a single thermal cycle for efficient manufacturing. The coupling of multiple process phenomena and the complex geometry of honeycomb cores, however, can lead to defects in cured parts. Effects of co-cure on void formation at the tool-side facesheet surface remain unclear. We employ autoclave processing and an in situ visualization technique to elucidate physical mechanisms by which surface porosity forms, and the effects of pressure on this formation. Results displayed a multi-stage development, including evacuation of entrapped air, followed by evolution and subsequent entrapment of dissolved volatiles in the prepreg resin, and demonstrated the utility of elevated pressure in reducing porosity. These findings describe the physics underlying porosity formation at the tool-facesheet interface, and provide insight into potential mitigation strategies to produce sandwich panels with defect-free facesheet surfaces. Graphical Abstract
{"title":"Surface porosity development in tool-side facesheets of honeycomb core sandwich structures during co-cure","authors":"D. Zebrine, Elana Wadhwani, S. Nutt","doi":"10.1080/20550340.2022.2056313","DOIUrl":"https://doi.org/10.1080/20550340.2022.2056313","url":null,"abstract":"Abstract Co-cure of honeycomb core sandwich structures combines the consolidation of composite prepreg facesheets with bonding of facesheets to a low-density core in a single thermal cycle for efficient manufacturing. The coupling of multiple process phenomena and the complex geometry of honeycomb cores, however, can lead to defects in cured parts. Effects of co-cure on void formation at the tool-side facesheet surface remain unclear. We employ autoclave processing and an in situ visualization technique to elucidate physical mechanisms by which surface porosity forms, and the effects of pressure on this formation. Results displayed a multi-stage development, including evacuation of entrapped air, followed by evolution and subsequent entrapment of dissolved volatiles in the prepreg resin, and demonstrated the utility of elevated pressure in reducing porosity. These findings describe the physics underlying porosity formation at the tool-facesheet interface, and provide insight into potential mitigation strategies to produce sandwich panels with defect-free facesheet surfaces. Graphical Abstract","PeriodicalId":7243,"journal":{"name":"Advanced Manufacturing: Polymer & Composites Science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81031646","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-02-15DOI: 10.1080/20550340.2022.2041221
L. Fazzi, G. Struzziero, C. Dransfeld, R. Groves
Abstract The unique sensing features of the tilted Fibre Bragg Grating (TFBG) as a single three-parameter optical sensor are demonstrated in this work, to monitor the manufacturing process of composite materials produced using Vacuum Assisted Resin Transfer Moulding (VARTM) process. Each TFBG sensor can measure simultaneously and separately strain, temperature and refractive index (RI) of the material where the optical fibre is embedded. A TFBG embedded in a 2 mm glass-fibre/epoxy composite plate was used to measure the thermomechanical variations induced during the curing process. At the same time, the RI measurements, performed with the same TFBG sensor, can estimate the degree of cure of the resin. The TFBG sensor shows to be a valid and promising technology to improve the state of art of sensing and monitoring in composite material manufacturing. Graphical Abstract
{"title":"A single three-parameter tilted fibre Bragg grating sensor to monitor the thermosetting composite curing process","authors":"L. Fazzi, G. Struzziero, C. Dransfeld, R. Groves","doi":"10.1080/20550340.2022.2041221","DOIUrl":"https://doi.org/10.1080/20550340.2022.2041221","url":null,"abstract":"Abstract The unique sensing features of the tilted Fibre Bragg Grating (TFBG) as a single three-parameter optical sensor are demonstrated in this work, to monitor the manufacturing process of composite materials produced using Vacuum Assisted Resin Transfer Moulding (VARTM) process. Each TFBG sensor can measure simultaneously and separately strain, temperature and refractive index (RI) of the material where the optical fibre is embedded. A TFBG embedded in a 2 mm glass-fibre/epoxy composite plate was used to measure the thermomechanical variations induced during the curing process. At the same time, the RI measurements, performed with the same TFBG sensor, can estimate the degree of cure of the resin. The TFBG sensor shows to be a valid and promising technology to improve the state of art of sensing and monitoring in composite material manufacturing. Graphical Abstract","PeriodicalId":7243,"journal":{"name":"Advanced Manufacturing: Polymer & Composites Science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77982582","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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