Pub Date : 2020-04-02DOI: 10.1080/20550340.2020.1750329
Chantal M de Zeeuw, D. Peeters, O. Bergsma, R. Benedictus
Abstract For the application of composite materials to become more widespread and replace traditional materials their manufacturing processes and final products will need to be competitive and be e.g. lighter, stronger or stiffer and quicker, easier or more cost-efficient to produce than traditional materials. The state of the art for pick-and-place operations for the manufacturing of composite parts focuses on handling single lab-sized layers at undisclosed speeds. The process could however be more competitive by being able to handle more and larger layers in a faster manner than currently presented in research. The aim of the paper is to evaluate the existing pick-and-place strategies on their suitability for the swift automated handling of multiple large-sized layers of reinforcement. The review shows that many of the existing techniques could be suitable for different scenario’s and discusses which factors are to be taken into account when dealing with large layers, more than one layer or rapid handling.
{"title":"Strategies for swift automated pick-and-place operations of multiple large-sized layers of reinforcement - a critical review","authors":"Chantal M de Zeeuw, D. Peeters, O. Bergsma, R. Benedictus","doi":"10.1080/20550340.2020.1750329","DOIUrl":"https://doi.org/10.1080/20550340.2020.1750329","url":null,"abstract":"Abstract For the application of composite materials to become more widespread and replace traditional materials their manufacturing processes and final products will need to be competitive and be e.g. lighter, stronger or stiffer and quicker, easier or more cost-efficient to produce than traditional materials. The state of the art for pick-and-place operations for the manufacturing of composite parts focuses on handling single lab-sized layers at undisclosed speeds. The process could however be more competitive by being able to handle more and larger layers in a faster manner than currently presented in research. The aim of the paper is to evaluate the existing pick-and-place strategies on their suitability for the swift automated handling of multiple large-sized layers of reinforcement. The review shows that many of the existing techniques could be suitable for different scenario’s and discusses which factors are to be taken into account when dealing with large layers, more than one layer or rapid handling.","PeriodicalId":7243,"journal":{"name":"Advanced Manufacturing: Polymer & Composites Science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80577341","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 : 2020-04-02DOI: 10.1080/20550340.2020.1764236
Omid Aghababaei Tafreshi, Suong van Hoa, F. Shadmehri, D. Hoang, D. Rosca
Abstract In heat transfer analysis of AFP process using a hot gas torch, the convective heat transfer which occurs between the hot gas flow generated by a torch nozzle and a composite substrate plays an important role in the heat transfer mechanism. In order to model the convective heat transfer, a local heat flux equation is utilized where is the energy flow per unit of area per unit of time, h is the convective heat transfer coefficient between the hot gas torch and the composite surface, and accounts for the temperature difference between the two media. This coefficient h is dependent on various number of parameters such as nozzle geometry and its configuration relative to the surface of the substrate, type and configuration of the roller, gas flow rate, temperature of the gas, type of the gas etc. Researchers on the heat transfer analysis for automated composites manufacturing have used values of h that vary from 80 W/m2K to 2500 W/m2K. This large range gives rise to uncertainties in the determination of important behavior such as the temperature distributions, residual stresses, and deformations of the composite structures due to the manufacturing process. The reason for these large differences can be due to the differences in the process parameters in each of the studies. The process parameters can include the volume flow rate of the hot gas, the gas temperature, the distance between the nozzle exit and the surface of the composite plate, the angle of the torch with respect to the surface of the substrate etc. In addition, the value of the h coefficient may not be constant over the heating length of the process. The purpose of this paper is three fold: 1. To investigate the AFP process parameters that may affect h. 2. To investigate different methods for the determination of h, and 3. To develop a procedure for less-time-consuming determination of h for the purpose of analysis for residual stresses and deformations. Graphical Abstract
{"title":"Determination of convective heat transfer coefficient for automated fiber placement (AFP) for thermoplastic composites using hot gas torch","authors":"Omid Aghababaei Tafreshi, Suong van Hoa, F. Shadmehri, D. Hoang, D. Rosca","doi":"10.1080/20550340.2020.1764236","DOIUrl":"https://doi.org/10.1080/20550340.2020.1764236","url":null,"abstract":"Abstract In heat transfer analysis of AFP process using a hot gas torch, the convective heat transfer which occurs between the hot gas flow generated by a torch nozzle and a composite substrate plays an important role in the heat transfer mechanism. In order to model the convective heat transfer, a local heat flux equation is utilized where is the energy flow per unit of area per unit of time, h is the convective heat transfer coefficient between the hot gas torch and the composite surface, and accounts for the temperature difference between the two media. This coefficient h is dependent on various number of parameters such as nozzle geometry and its configuration relative to the surface of the substrate, type and configuration of the roller, gas flow rate, temperature of the gas, type of the gas etc. Researchers on the heat transfer analysis for automated composites manufacturing have used values of h that vary from 80 W/m2K to 2500 W/m2K. This large range gives rise to uncertainties in the determination of important behavior such as the temperature distributions, residual stresses, and deformations of the composite structures due to the manufacturing process. The reason for these large differences can be due to the differences in the process parameters in each of the studies. The process parameters can include the volume flow rate of the hot gas, the gas temperature, the distance between the nozzle exit and the surface of the composite plate, the angle of the torch with respect to the surface of the substrate etc. In addition, the value of the h coefficient may not be constant over the heating length of the process. The purpose of this paper is three fold: 1. To investigate the AFP process parameters that may affect h. 2. To investigate different methods for the determination of h, and 3. To develop a procedure for less-time-consuming determination of h for the purpose of analysis for residual stresses and deformations. Graphical Abstract","PeriodicalId":7243,"journal":{"name":"Advanced Manufacturing: Polymer & Composites Science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86488118","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 : 2020-04-02DOI: 10.1080/20550340.2020.1768348
S. Schechter, Lessa K. Grunenfelder, S. Nutt
Abstract Prepregs with discontinuous resin (semi-pregs) impart robustness to vacuum-bag-only processing of composites. Limited guidance exists for evaluating advantageous resin patterns (i.e. dry space dimensions required to achieve both efficient air evacuation and full resin infiltration during cure). A flow front model was developed based on resin cure kinetics and rheological behavior, and then determined maximum dry space dimensions for semi-pregs under a range of realistic manufacturing conditions. Model predictions were validated in situ. Under controlled laboratory cure conditions, small surface openings (≤3.7 mm) resulted in full resin infiltration. Under adverse conditions (resin with accrued out-time), the maximum opening size dropped 40% (to ≤2.2 mm). Using a mathematical model, air evacuation time was calculated for various feature sizes using permeability measurements. Model predictions were tested and verified via fabrication of laminates. This methodology can be applied to other resin systems to guide vacuum-bag-only prepreg design and support robust production of composites. Graphical Abstract
{"title":"Air evacuation and resin impregnation in semi-pregs: effects of feature dimensions","authors":"S. Schechter, Lessa K. Grunenfelder, S. Nutt","doi":"10.1080/20550340.2020.1768348","DOIUrl":"https://doi.org/10.1080/20550340.2020.1768348","url":null,"abstract":"Abstract Prepregs with discontinuous resin (semi-pregs) impart robustness to vacuum-bag-only processing of composites. Limited guidance exists for evaluating advantageous resin patterns (i.e. dry space dimensions required to achieve both efficient air evacuation and full resin infiltration during cure). A flow front model was developed based on resin cure kinetics and rheological behavior, and then determined maximum dry space dimensions for semi-pregs under a range of realistic manufacturing conditions. Model predictions were validated in situ. Under controlled laboratory cure conditions, small surface openings (≤3.7 mm) resulted in full resin infiltration. Under adverse conditions (resin with accrued out-time), the maximum opening size dropped 40% (to ≤2.2 mm). Using a mathematical model, air evacuation time was calculated for various feature sizes using permeability measurements. Model predictions were tested and verified via fabrication of laminates. This methodology can be applied to other resin systems to guide vacuum-bag-only prepreg design and support robust production of composites. Graphical Abstract","PeriodicalId":7243,"journal":{"name":"Advanced Manufacturing: Polymer & Composites Science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84782774","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 : 2020-01-02DOI: 10.1080/20550340.2020.1722910
P. Hergan, E. Fauster, Daniela Perkonigg, G. Pinter, R. Schledjewski
Abstract This work describes a model-based methodology to improve the bonding quality between the metal and composite constituents of one-shot-hybrid resin transfer moulding (OSH-RTM) parts. In order to reduce void induced defects in the interface an ideal flow front velocity needs to be achieved. This ideal flow front velocity is characterised by capillary rise experiments at the used carbon fibre textile. The flow front velocity during mould filling is controlled by the use of pressure sensors and Darcy’s law. Therefore, viscosity characterisation of the resin system and permeability measurements of the preform were carried out. The interface of the produced OSH-RTM roof bar for a car is tested on a component test rig imitating the load of a side impact at a car. A t-test was carried out to prove that the flow-speed-controlled injection strategy is advantageous compared to a constant mass flow injection by means of a higher maximum load transferable by the interface of the hybrid part. Graphical Abstract
{"title":"Flow-speed-controlled quality optimisation for one-shot-hybrid RTM parts","authors":"P. Hergan, E. Fauster, Daniela Perkonigg, G. Pinter, R. Schledjewski","doi":"10.1080/20550340.2020.1722910","DOIUrl":"https://doi.org/10.1080/20550340.2020.1722910","url":null,"abstract":"Abstract This work describes a model-based methodology to improve the bonding quality between the metal and composite constituents of one-shot-hybrid resin transfer moulding (OSH-RTM) parts. In order to reduce void induced defects in the interface an ideal flow front velocity needs to be achieved. This ideal flow front velocity is characterised by capillary rise experiments at the used carbon fibre textile. The flow front velocity during mould filling is controlled by the use of pressure sensors and Darcy’s law. Therefore, viscosity characterisation of the resin system and permeability measurements of the preform were carried out. The interface of the produced OSH-RTM roof bar for a car is tested on a component test rig imitating the load of a side impact at a car. A t-test was carried out to prove that the flow-speed-controlled injection strategy is advantageous compared to a constant mass flow injection by means of a higher maximum load transferable by the interface of the hybrid part. Graphical Abstract","PeriodicalId":7243,"journal":{"name":"Advanced Manufacturing: Polymer & Composites Science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85827401","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 : 2020-01-02DOI: 10.1080/20550340.2020.1739402
Florian Mischo, C. Goergen, S. Schmeer, P. Mitschang
Abstract Carbon fiber reinforced polymer composites (CFRPC) are one of the promising lightweight materials in car production and show excellent energy absorption potential. In this paper, crash absorbers made of recycled carbon staple fibers (rCSF) and polyamide 6 are manufactured by an advanced thermoforming process in a multi-segment mold. The innovative wave design is meant to prevent the crash absorber from unintended crushing effects like bending or buckling and easy to manufacture by the investigated process. The formed crash absorbers were tested in a horizontal test rig by using a crash sled with an impact energy of 1925 J. The rCSF based crash absorbers feature a specific energy absorption (SEA) of 58.12 ± 0.58 J/g. Also, the standard deviation of the rCSF crash absorbers is remarkably low (1.0%). Thus, rCSF based crash absorbers represent a viable alternative to crash absorbers made of virgin fibers. Graphical Abstract
{"title":"Use of recycled carbon staple fibers in an advanced thermoforming process and analysis of its crash performance","authors":"Florian Mischo, C. Goergen, S. Schmeer, P. Mitschang","doi":"10.1080/20550340.2020.1739402","DOIUrl":"https://doi.org/10.1080/20550340.2020.1739402","url":null,"abstract":"Abstract Carbon fiber reinforced polymer composites (CFRPC) are one of the promising lightweight materials in car production and show excellent energy absorption potential. In this paper, crash absorbers made of recycled carbon staple fibers (rCSF) and polyamide 6 are manufactured by an advanced thermoforming process in a multi-segment mold. The innovative wave design is meant to prevent the crash absorber from unintended crushing effects like bending or buckling and easy to manufacture by the investigated process. The formed crash absorbers were tested in a horizontal test rig by using a crash sled with an impact energy of 1925 J. The rCSF based crash absorbers feature a specific energy absorption (SEA) of 58.12 ± 0.58 J/g. Also, the standard deviation of the rCSF crash absorbers is remarkably low (1.0%). Thus, rCSF based crash absorbers represent a viable alternative to crash absorbers made of virgin fibers. Graphical Abstract","PeriodicalId":7243,"journal":{"name":"Advanced Manufacturing: Polymer & Composites Science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88748260","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 : 2020-01-02DOI: 10.1080/20550340.2020.1728476
Wei Hu, S. Nutt
Abstract Air removal prior to cure is critical for limiting porosity during vacuum bag-only (VBO) processing of prepregs. In this study, the effects of pre-cure dwell temperature (debulk) on air evacuation were investigated for both plain weave (PW) and unidirectional (UD) prepregs. In situ observations revealed that increasing dwell temperature promoted inter-ply air evacuation (by as much as 2x for UD prepregs). Through-thickness gas permeability increased with increasing temperature and decreased with increasing number of plies. The decrease in in-plane permeability during heated debulk was attributed to increased tow impregnation. The findings provide guidelines for cure cycle optimization. Heated debulk enhanced air evacuation in PW laminates, particularly as laminate width/thickness ratios exceed a threshold value. However, warm debulks were less effective, particularly for thicker laminates (>8 plies). Graphical abstract
{"title":"Effects of debulk temperature on air evacuation during vacuum bag-only prepreg processing","authors":"Wei Hu, S. Nutt","doi":"10.1080/20550340.2020.1728476","DOIUrl":"https://doi.org/10.1080/20550340.2020.1728476","url":null,"abstract":"Abstract Air removal prior to cure is critical for limiting porosity during vacuum bag-only (VBO) processing of prepregs. In this study, the effects of pre-cure dwell temperature (debulk) on air evacuation were investigated for both plain weave (PW) and unidirectional (UD) prepregs. In situ observations revealed that increasing dwell temperature promoted inter-ply air evacuation (by as much as 2x for UD prepregs). Through-thickness gas permeability increased with increasing temperature and decreased with increasing number of plies. The decrease in in-plane permeability during heated debulk was attributed to increased tow impregnation. The findings provide guidelines for cure cycle optimization. Heated debulk enhanced air evacuation in PW laminates, particularly as laminate width/thickness ratios exceed a threshold value. However, warm debulks were less effective, particularly for thicker laminates (>8 plies). Graphical abstract","PeriodicalId":7243,"journal":{"name":"Advanced Manufacturing: Polymer & Composites Science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88867362","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 : 2020-01-02DOI: 10.1080/20550340.2019.1709010
S. Saseendran, D. Berglund, J. Varna
Abstract A thermo-rheologically complex linear viscoelastic material model, accounting for temperature and degree of cure (DoC), is developed starting with series expansion of the Helmholtz free energy and systematically implementing simplifying assumptions regarding the material behavior. In addition to the temperature and DoC dependent shift factor present in rheologically simple models, the derived novel model contains three cure and temperature dependent functions. The first function is identified as the rubbery modulus. The second is a weight factor to the transient integral term in the model and reflects the current temperature and cure state, whereas the third function is under the sign of the convolution integral, thus affecting the “memory” of the material. An incremental form of this model is presented which, due to improved approximation inside the time increment, has better numerical convergence than most of the similar forms. Parametric analysis is performed simulating stress development in a polymer, geometrically constrained in the mold during curing and cool-down. The importance of using proper viscoelastic model is shown, and the role of parameters in the model is revealed and discussed. Graphical Abstract
{"title":"Viscoelastic model with complex rheological behavior (VisCoR): incremental formulation","authors":"S. Saseendran, D. Berglund, J. Varna","doi":"10.1080/20550340.2019.1709010","DOIUrl":"https://doi.org/10.1080/20550340.2019.1709010","url":null,"abstract":"Abstract A thermo-rheologically complex linear viscoelastic material model, accounting for temperature and degree of cure (DoC), is developed starting with series expansion of the Helmholtz free energy and systematically implementing simplifying assumptions regarding the material behavior. In addition to the temperature and DoC dependent shift factor present in rheologically simple models, the derived novel model contains three cure and temperature dependent functions. The first function is identified as the rubbery modulus. The second is a weight factor to the transient integral term in the model and reflects the current temperature and cure state, whereas the third function is under the sign of the convolution integral, thus affecting the “memory” of the material. An incremental form of this model is presented which, due to improved approximation inside the time increment, has better numerical convergence than most of the similar forms. Parametric analysis is performed simulating stress development in a polymer, geometrically constrained in the mold during curing and cool-down. The importance of using proper viscoelastic model is shown, and the role of parameters in the model is revealed and discussed. Graphical Abstract","PeriodicalId":7243,"journal":{"name":"Advanced Manufacturing: Polymer & Composites Science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73733565","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 : 2020-01-02DOI: 10.1080/20550340.2019.1710023
Y. Ibrahim, A. Elkholy, Jonathon S. Schofield, Garrett W. Melenka, R. Kempers
Abstract 3D printing, especially fused filament fabrication, presents a potentially attractive manufacturing technique for thermal applications such as polymer heat exchangers due to the ability to create complex internal geometries which can be used to enhance convective heat transfer. Recently, commercial and modified open-source printers have utilized continuous fibers such as carbon fiber to create continuous fiber reinforced polymer composites (FRPCs) which enhance the mechanical properties of the printed products. This continuous filler network can also serve to improve thermal conductivity. In this study, the effective thermal conductivity of 3D-printed FRPCs is characterized using a steady-state, modified, guarded hot plate apparatus. The effect of the fiber direction and volume fraction on the effective thermal conductivity of the 3D-printed composites was characterized experimentally and modeled analytically using series and parallel models. Thermal conductivities of up to 2.97 W/mK were measured for samples in which the fibers were aligned with the direction of heat flow. Measured values were in good agreement with analytical model predictions. The importance of fiber conductivity on overall performance of the FRPCs was further demonstrated using a handlaid-up, pitch-based carbon fiber sample which exhibited an effective thermal conductivity of 23.6 W/mK. Graphical Abstract
{"title":"Effective thermal conductivity of 3D-printed continuous fiber polymer composites","authors":"Y. Ibrahim, A. Elkholy, Jonathon S. Schofield, Garrett W. Melenka, R. Kempers","doi":"10.1080/20550340.2019.1710023","DOIUrl":"https://doi.org/10.1080/20550340.2019.1710023","url":null,"abstract":"Abstract 3D printing, especially fused filament fabrication, presents a potentially attractive manufacturing technique for thermal applications such as polymer heat exchangers due to the ability to create complex internal geometries which can be used to enhance convective heat transfer. Recently, commercial and modified open-source printers have utilized continuous fibers such as carbon fiber to create continuous fiber reinforced polymer composites (FRPCs) which enhance the mechanical properties of the printed products. This continuous filler network can also serve to improve thermal conductivity. In this study, the effective thermal conductivity of 3D-printed FRPCs is characterized using a steady-state, modified, guarded hot plate apparatus. The effect of the fiber direction and volume fraction on the effective thermal conductivity of the 3D-printed composites was characterized experimentally and modeled analytically using series and parallel models. Thermal conductivities of up to 2.97 W/mK were measured for samples in which the fibers were aligned with the direction of heat flow. Measured values were in good agreement with analytical model predictions. The importance of fiber conductivity on overall performance of the FRPCs was further demonstrated using a handlaid-up, pitch-based carbon fiber sample which exhibited an effective thermal conductivity of 23.6 W/mK. Graphical Abstract","PeriodicalId":7243,"journal":{"name":"Advanced Manufacturing: Polymer & Composites Science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82033318","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 : 2019-10-02DOI: 10.1080/20550340.2019.1680514
Anubhav Singh, N. Reynolds, C. Carnegie, C. Micallef, Elspeth M. Keating, J. Winnett, A. Barnett, S. Barbour, D. Hughes
Abstract This work investigates the application of a rapid variothermal moulding process for direct processing of a braided thermoplastic commingled yarn. The process uses locally controllable, responsive tooling which provides opportunities for optimum part quality and significantly reduced cycle times compared with conventional processes. The proposed process was used to directly manufacture hollow beam structures from dry commingled braided preforms. It was demonstrated that the cycle time using the rapid process was reduced by more than 90% as compared to a conventional bladder moulding process, resulting in a total cycle time of 14 min. Additionally, initial three point flexure test results indicated an improvement in the mechanical performance of the resultant parts as compared to the benchmark. Graphical Abstract
{"title":"A novel route for volume manufacturing of hollow braided composite beam structures","authors":"Anubhav Singh, N. Reynolds, C. Carnegie, C. Micallef, Elspeth M. Keating, J. Winnett, A. Barnett, S. Barbour, D. Hughes","doi":"10.1080/20550340.2019.1680514","DOIUrl":"https://doi.org/10.1080/20550340.2019.1680514","url":null,"abstract":"Abstract This work investigates the application of a rapid variothermal moulding process for direct processing of a braided thermoplastic commingled yarn. The process uses locally controllable, responsive tooling which provides opportunities for optimum part quality and significantly reduced cycle times compared with conventional processes. The proposed process was used to directly manufacture hollow beam structures from dry commingled braided preforms. It was demonstrated that the cycle time using the rapid process was reduced by more than 90% as compared to a conventional bladder moulding process, resulting in a total cycle time of 14 min. Additionally, initial three point flexure test results indicated an improvement in the mechanical performance of the resultant parts as compared to the benchmark. Graphical Abstract","PeriodicalId":7243,"journal":{"name":"Advanced Manufacturing: Polymer & Composites Science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83906082","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 : 2019-10-02DOI: 10.1080/20550340.2019.1703334
T. Zenker, F. Bruckner, K. Drechsler
Abstract Automated Fiber Placement of thermoplastic unidirectional tape materials offers several advantages over conventional organosheets, such as enhanced part performance through tailored fiber architecture, and economic and ecological benefits due to scrap reduction. Because material is cut perpendicular to the feeding direction in state-of-the-art machine technology, triangular gaps and overlaps occur when geometrically complex layups are fabricated. Their effect on part properties is unknown for thermoplastic materials. This study investigates the influence of various defect configurations on laminate quality and mechanical performance for different consolidation processes. Analysis of microsections prepared from post-consolidation specimens shows out-of-plane undulations in defect areas. The undulation extent is quantified by angle and deflection. Tensile and compressive testing is performed. Gaps reduce ultimate tensile and compressive strength significantly for variothermal press and autoclave consolidation. Digital-image-correlation-based strain measurement during tensile testing shows strain concentration in the defect area for these specimens. Specimens consolidated in an isothermal stamp forming process show no comparable stress concentration, as well as no reduced ultimate strength. Specimens containing overlaps generally show a better performance in terms of ultimate strength compared to those containing gaps. Even though no full factorial design of experiments was used, the results obtained from this study can be used as a baseline for sector-boundary design strategies. The definition of defect-specific knock-down factors would be a next step towards the solid engineering of thermoplastic Automated Fiber Placement parts.
{"title":"Effects of defects on laminate quality and mechanical performance in thermoplastic Automated Fiber Placement-based process chains","authors":"T. Zenker, F. Bruckner, K. Drechsler","doi":"10.1080/20550340.2019.1703334","DOIUrl":"https://doi.org/10.1080/20550340.2019.1703334","url":null,"abstract":"Abstract Automated Fiber Placement of thermoplastic unidirectional tape materials offers several advantages over conventional organosheets, such as enhanced part performance through tailored fiber architecture, and economic and ecological benefits due to scrap reduction. Because material is cut perpendicular to the feeding direction in state-of-the-art machine technology, triangular gaps and overlaps occur when geometrically complex layups are fabricated. Their effect on part properties is unknown for thermoplastic materials. This study investigates the influence of various defect configurations on laminate quality and mechanical performance for different consolidation processes. Analysis of microsections prepared from post-consolidation specimens shows out-of-plane undulations in defect areas. The undulation extent is quantified by angle and deflection. Tensile and compressive testing is performed. Gaps reduce ultimate tensile and compressive strength significantly for variothermal press and autoclave consolidation. Digital-image-correlation-based strain measurement during tensile testing shows strain concentration in the defect area for these specimens. Specimens consolidated in an isothermal stamp forming process show no comparable stress concentration, as well as no reduced ultimate strength. Specimens containing overlaps generally show a better performance in terms of ultimate strength compared to those containing gaps. Even though no full factorial design of experiments was used, the results obtained from this study can be used as a baseline for sector-boundary design strategies. The definition of defect-specific knock-down factors would be a next step towards the solid engineering of thermoplastic Automated Fiber Placement parts.","PeriodicalId":7243,"journal":{"name":"Advanced Manufacturing: Polymer & Composites Science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91008871","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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