2019
Schmidt, Carsten; Hocke, Tristan; Denkena, Berend
Artificial intelligence for non-destructive testing of CFRP prepreg materials Artikel
In: Production Engineering, S. 1-10, 2019.
Abstract | Links | BibTeX | Schlagwörter: Artificial Intelligence, Automated Fiber Placement, Composite Manufacturing, Composite Structures, Defects, Prepreg, Quality Assurance, Thermal Imaging
@article{Schmidt2019,
title = {Artificial intelligence for non-destructive testing of CFRP prepreg materials},
author = {Carsten Schmidt and Tristan Hocke and Berend Denkena},
url = {https://link.springer.com/article/10.1007%2Fs11740-019-00913-3},
doi = {https://doi.org/10.1007/s11740-019-00913-3},
year = {2019},
date = {2019-07-02},
journal = {Production Engineering},
pages = {1-10},
abstract = {This paper presents a concept of the quality assurance for CFRP prepreg materials and focusses on the classification of thermographic images using convolution neural networks (CNNs). The method for non-destructive testing of CFRP prepreg materials combines a laser-triangulation sensor and an infrared camera to monitor both, the geometry and the impregnation of the prepreg material. The aim is to ensure a high material quality excluding any defective material in an early stage of the process chain of the production of CFRP components. As a result, the reliability of Automated-Fiber-Placement processes utilizing this previously tested material increases. Therefore, an artificial intelligence is set up to classify the thermal images of the CFRP material. Two different architectures of CNN are trained and validated with data sets consisting of thermal images of several prepreg materials and different material defects, such as geometric deviations and varying fiber-matrix-ratios caused by an incorrect impregnation. The CNNs are able to differentiate prepreg materials and to detect and classify certain material-independent defects for known and trained prepreg materials.},
keywords = {Artificial Intelligence, Automated Fiber Placement, Composite Manufacturing, Composite Structures, Defects, Prepreg, Quality Assurance, Thermal Imaging},
pubstate = {published},
tppubtype = {article}
}
Krieglsteiner, Joscha; Horst, Peter; Schmidt, Carsten
In: Aircraft Engineering and Aerospace Technology , Bd. 91, Nr. 4, S. 607-619, 2019.
Abstract | Links | BibTeX | Schlagwörter: Composite Structures, Design Method, Preliminary design
@article{Krieglsteiner2019b,
title = {Definition and Representation of Stiffened Shell Structures in the Context of an Integrated Development Process},
author = {Joscha Krieglsteiner and Peter Horst and Carsten Schmidt},
url = {https://doi.org/10.1108/AEAT-07-2018-0205},
doi = {10.1108/AEAT-07-2018-0205},
year = {2019},
date = {2019-03-28},
journal = {Aircraft Engineering and Aerospace Technology },
volume = {91},
number = {4},
pages = {607-619},
abstract = {Purpose A novel development process aims at finding solutions for lightweight stiffened shell structures and their efficient production. To respect the strong interdependency of structural design and production planning, particularly observed for composite structures, it is of high interest to start considering production effects in early development phases. This integrated approach requires an integrated representation of structure and production. The purpose of this study is to investigate the scope of relevant data and to find a structure for its representation. Design/methodology/approach The development task is analyzed and a system of so-called solution dimensions is presented, which covers all important aspects of stiffened shell structures and their production. An integrated product data model is developed to cover all of the solution dimensions. Findings The product data model consists of five coherent partial models. It is explained how these models are defined and how they are connected to each other. An academic example of an aircraft fuselage panel is used to demonstrate the definition process. It is shown how even complex structural concepts are defined systematically. Practical implications It is explained how this integrated product data model is used in a software project for the development of aircraft fuselage structures. Originality/value The presented approach for the definition and representation of stiffened shell structures enables the developer, e.g. of aircraft fuselage, to respect the crucial criterion of manufacturability from early development phases on. Further, new design approaches, e.g. as inspired by topology optimization, can be considered.},
keywords = {Composite Structures, Design Method, Preliminary design},
pubstate = {published},
tppubtype = {article}
}
2018
Reichert, Lisa; Krieglsteiner, Joscha; Schmidt, Carsten; Horst, Peter
Simplified Representation of Complex Structural Components for Finite-Element-Analysis Konferenzbeitrag
In: ECCM18, (Hrsg.): 2018.
BibTeX | Schlagwörter: Composite Structures, Modelling, Stiffener Profiles
@inproceedings{Reichert2018,
title = {Simplified Representation of Complex Structural Components for Finite-Element-Analysis},
author = {Lisa Reichert and Joscha Krieglsteiner and Carsten Schmidt and Peter Horst},
editor = {ECCM18},
year = {2018},
date = {2018-06-25},
keywords = {Composite Structures, Modelling, Stiffener Profiles},
pubstate = {published},
tppubtype = {inproceedings}
}
Groß, Lukas; Herwig, Alexander; Berg, David C.; Schmidt, Carsten; Denkena, Berend; Horst, Peter; Meiners, Dieter
Production-based design of a hybrid load introduction element for thin-walled CFRP Structures Artikel
In: Production Engineering, S. 8, 2018, ISSN: 1863-7353.
Abstract | Links | BibTeX | Schlagwörter: Automated Fiber Placement, Composite Structures, Embedded Load Introduction Element, Fiber-Metal Laminate, Multilayer Insert
@article{Groß2018,
title = {Production-based design of a hybrid load introduction element for thin-walled CFRP Structures},
author = {Lukas Groß and Alexander Herwig and David C. Berg and Carsten Schmidt and Berend Denkena and Peter Horst and Dieter Meiners},
url = {https://link.springer.com/article/10.1007/s11740-018-0821-4},
doi = {https://doi.org/10.1007/s11740-018-0821-4},
issn = {1863-7353},
year = {2018},
date = {2018-03-21},
journal = {Production Engineering},
pages = {8},
abstract = {The project “Multi-Layer Inserts” (MLI) proposes a new design for inserts used in thin-walled CFRP structures. The proposed inserts consist of multiple thin metal sheets and is build up simultaneously with the laminate in an intrinsic hybridization process, eliminating time-consuming post-processing steps. Furthermore, at equal weight, such inserts greatly increase the bonding area between metal and CFRP in comparison to conventional inserts. This results in a significant increase of the loads that can be transmitted into the CFRP. The present work discusses how the shape of the metal sheets which the proposed inserts consist of influences the mechanical properties of the surrounding laminate. This influence is investigated by measuring the strain distribution during tensile tests by means of digital image correlation. The strain distributions around the following three different MLI design approaches are compared: An elliptical metal sheet, which is expected to be ideal in terms of mechanical performance of the overall structure; a cross-shape metal sheet representing a production-driven simplification which only requires the ability to perform cuts in individual tows perpendicular to the laying direction and can be performed by state-of-the-art AFP systems; and lastly, a compromise between manufacturability and achieved mechanical performance, a decagonal metal sheet design, which requires angled cuts of the fiber tows. It is shown, that the decagon is able to evenly spread the strain over a larger area and is therefore able to significantly reduce the maximum strain values compared to a cross-shape metal sheet, while still being automatable.},
keywords = {Automated Fiber Placement, Composite Structures, Embedded Load Introduction Element, Fiber-Metal Laminate, Multilayer Insert},
pubstate = {published},
tppubtype = {article}
}
2017
Denkena, Berend; Horst, Peter; Schmidt, Carsten; Behr, Matthias; Krieglsteiner, Joscha
Estimation of production cost in an early design stage of CFRP lightweight structures Artikel
In: Procedia CIRP, Bd. 62, S. 45-50, 2017.
Abstract | Links | BibTeX | Schlagwörter: Composite Structures, Design Method, Planning, Production
@article{Denkena2017,
title = {Estimation of production cost in an early design stage of CFRP lightweight structures },
author = {Berend Denkena and Peter Horst and Carsten Schmidt and Matthias Behr and Joscha Krieglsteiner},
url = {http://ac.els-cdn.com/S2212827116306497/1-s2.0-S2212827116306497-main.pdf?_tid=3a995538-9417-11e7-b3af-00000aacb35f&acdnat=1504821494_6d4b8f585d0dab563050c677069e40d1},
year = {2017},
date = {2017-09-01},
journal = { Procedia CIRP},
volume = {62},
pages = {45-50},
abstract = {Development of composite structure which are both light and economically competitive is challenging. A new method for the development of CRFP lightweight structures implements a frequent interaction of design and production planning starting in an early design stage. As part of this, production alternatives need to be compared in terms of cost and impact on structural mass. This paper describes how a software module automatically determines suitable process chains based on a preliminary structural design. Cost of production is estimated using analytical process models dealing with imprecise design information. Applied to an aircraft fuselage panel, the method estimates cost and mass of different production alternatives.},
keywords = {Composite Structures, Design Method, Planning, Production},
pubstate = {published},
tppubtype = {article}
}
Brüning, Jan; Schmidt, Carsten; Denkena, Berend
Erhöhung der Prozesssicherheit von Automated-Fiber-Placement-Prozessen Artikel
In: Ingenieurspiegel, Bd. 1, S. 29-31, 2017.
Abstract | BibTeX | Schlagwörter: Composite Structures, Process Monitoring, Thermal Imaging
@article{Brüning2017,
title = {Erhöhung der Prozesssicherheit von Automated-Fiber-Placement-Prozessen},
author = {Jan Brüning and Carsten Schmidt and Berend Denkena},
year = {2017},
date = {2017-01-16},
journal = {Ingenieurspiegel},
volume = {1},
pages = {29-31},
abstract = {In der Luftfahrtindustrie ist Automated Fiber Placement (AFP) eine der führenden Fertigungstechnologien für die kosteneffektive Serienproduktion von hochqualitativen Leichtbaustrukturen. Allerdings bieten sowohl die automatisierten Fertigungssysteme als auch die Prozessplanungssysteme noch ungenutzte Verbesserungspotenziale hinsichtlich Zuverlässigkeit und Effizienz.},
keywords = {Composite Structures, Process Monitoring, Thermal Imaging},
pubstate = {published},
tppubtype = {article}
}
2016
Schmidt, Carsten; Denkena, Berend; Groß, Lukas
Concept for automated production of CFRP-metal hybrid compounds integrated in an Automated Fiber Placement process Konferenz
10th CIRP Conference on Intelligent Computation in Manufacturing Engineering, Neapel, Italien, 2016.
Abstract | BibTeX | Schlagwörter: Automated Fiber Placement, Composite Structures, Intrinsic Hybridisation, Multilayer Insert
@conference{Schmidt2016b,
title = {Concept for automated production of CFRP-metal hybrid compounds integrated in an Automated Fiber Placement process},
author = {Carsten Schmidt and Berend Denkena and Lukas Groß},
year = {2016},
date = {2016-08-25},
booktitle = {10th CIRP Conference on Intelligent Computation in Manufacturing Engineering},
address = {Neapel, Italien},
abstract = {To solve the problem of load transmission into thin walled CFRP Structures, a new joining technology is being developed (Multi Layer Insert – MLI). It consists of multiple thin metal foils to distribute load optimally into every single CFRP layer. The placement process for the metal layers is integrated into an Automated Fiber Placement system. In this paper, a process sequence of MLI placement is presented containing the following steps: stockpiling of metal layers, separation, handling, positioning, lay up and fixation of metal layers during fiber placement. Moreover, the monitoring and control concept is discussed.},
keywords = {Automated Fiber Placement, Composite Structures, Intrinsic Hybridisation, Multilayer Insert},
pubstate = {published},
tppubtype = {conference}
}
Koch, Simon-F.; Barfuss, Daniel; Bobbert, Mathias; Groß, Lukas; Grützner, Raik; Riemer, Matthias; Stefaniak, Daniel; Wang, Zhen
Intrinsic hybrid composites for lightweight structures: New Process Chain Approaches Konferenz
Proceedings of 2016 WGP Congress, 2016.
Abstract | BibTeX | Schlagwörter: Automated Fiber Placement, Composite Structures, Intrinsic Hybridisation, Multilayer Insert
@conference{Koch2016,
title = {Intrinsic hybrid composites for lightweight structures: New Process Chain Approaches},
author = {Simon-F. Koch and Daniel Barfuss and Mathias Bobbert and Lukas Groß and Raik Grützner and Matthias Riemer and Daniel Stefaniak and Zhen Wang},
year = {2016},
date = {2016-08-25},
booktitle = {Proceedings of 2016 WGP Congress},
abstract = {This publication describes new process chain approaches for the manufacturing of intrinsic hybrid composites for lightweight structures. The introduced process chains show a variety of different part and sample types, like insert technology for fastening of hollow hybrid shafts and profiles. Another field of research are hybrid laminates with different layers of carbon fiber reinforced plastics stacked with aluminum or steel sheets. The derived process chains base on automated fiber placement, resin transfer molding, deep drawing, rotational molding and integral tube blow molding.},
keywords = {Automated Fiber Placement, Composite Structures, Intrinsic Hybridisation, Multilayer Insert},
pubstate = {published},
tppubtype = {conference}
}
Behr, Matthias; Schmidt, Carsten
Systematic Production Planning Method for CFRP Structures Artikel
In: Advanced Materials Research, Bd. Vol. 1140, S. S. 328-334, 2016.
Abstract | BibTeX | Schlagwörter: Composite Structures, Preliminary design, Production Planning
@article{Behr2016,
title = {Systematic Production Planning Method for CFRP Structures},
author = {Matthias Behr and Carsten Schmidt},
year = {2016},
date = {2016-08-25},
booktitle = {Proceedings of 2016 WGP Congress},
journal = {Advanced Materials Research},
volume = {Vol. 1140},
pages = {S. 328-334},
abstract = {A production planning method is presented which allows to systematically build process chains based on a preliminary design of a composite structure. The method uses the specific sequences of procedural steps that occur in the production of carbon fibre reinforced plastic (CFRP) structures, to build sub process chains for each sub component of the structure. Process restrictions are considered to evaluate the suitability of different production processes. To obtain the whole process chain of the structure, different joining methods are applied in addition to combine the sub components and it sub chains. The results of the presented method are used in a superior development procedure to investigate resulting impacts on the solution. Possible impacts could be the production costs or the material characteristics.},
keywords = {Composite Structures, Preliminary design, Production Planning},
pubstate = {published},
tppubtype = {article}
}
Denkena, Berend; Schmidt, Carsten; Behr, Matthias
Systematische Erstellung von Prozessketten in frühen Phasen der Produktentwicklung von CFK-Strukturen Konferenz
WGP Kongress 2016, 2016.
BibTeX | Schlagwörter: Composite Structures, Preliminary design, Production Planning
@conference{Denkena2016b,
title = {Systematische Erstellung von Prozessketten in frühen Phasen der Produktentwicklung von CFK-Strukturen},
author = {Berend Denkena and Carsten Schmidt and Matthias Behr},
year = {2016},
date = {2016-08-25},
booktitle = {WGP Kongress 2016},
keywords = {Composite Structures, Preliminary design, Production Planning},
pubstate = {published},
tppubtype = {conference}
}
Schmidt, Carsten; Weber, Patricc; Völtzer, Klaas; Deniz, Onur
Self-Configurable Production of CFRP Aerospace Components Based on Multi-Criteria Structural Optimization Konferenzbeitrag
In: CFK-Valley Convention, 2016.
Abstract | BibTeX | Schlagwörter: Composite Structures, Industry 4.0, Self Configurable Production
@inproceedings{Schmidt2016,
title = {Self-Configurable Production of CFRP Aerospace Components Based on Multi-Criteria Structural Optimization },
author = {Carsten Schmidt and Patricc Weber and Klaas Völtzer and Onur Deniz},
year = {2016},
date = {2016-06-17},
booktitle = {CFK-Valley Convention},
abstract = {Increased utilization of composite materials in a wide range of applications and industries due to their specific properties such as strength-to weight ratio, damage tolerance, reduced maintenance costs and flexibility let to advanced requirements on production methodologies and increased demands on lightweight construction. To be well prepared for tomorrow´s market, lightweight industries must be able to response quickly to customer needs as well as controlling costs and manufacturing quality. Accompanying challenges of manufacturing individually designed lightweight components with predominantly small lot sizes have to be met with flexible production systems in a quick reconfigurable production environment. Process reliability particularly in single part production is a big challenge. To minimize the risk associated therewith, criteria like component producibility already have to be considered in the design phase and monitoring of the manufacturing process becomes more relevant to ensure desired material properties.
Within the interdisciplinary research project “High Performance Production of CFRP-Structures” (HP CFK), a generic approach for simultaneously developing lightweight aerospace components, automated fiber placement system and processes is developed. This presentation introduces the new multicriteria optimization framework that efficiently involves corresponding manufacturing analysis of developed aerospace composite structures with respect to production costs, producibility and material characteristics. In addition, a newly developed reconfigurable automated fiber placement system with adaptive force controlled compaction unit, whose technical characteristics are represented within the optimization framework, and an online thermal imaging system for monitoring fiber placement manufacturing processes are presented. It is shown, how component topologies easily improve and adapt themselves to the corresponding production technology due to returned process knowledge and manufacturing restrictions and hereby avoiding time consuming redesign iterations. The coupling of optimization framework and manufacturing system lead to a self-configuration of automated fiber placement processes and an individually parametrization of the monitoring system for part specific online quality control.
},
keywords = {Composite Structures, Industry 4.0, Self Configurable Production},
pubstate = {published},
tppubtype = {inproceedings}
}
Within the interdisciplinary research project “High Performance Production of CFRP-Structures” (HP CFK), a generic approach for simultaneously developing lightweight aerospace components, automated fiber placement system and processes is developed. This presentation introduces the new multicriteria optimization framework that efficiently involves corresponding manufacturing analysis of developed aerospace composite structures with respect to production costs, producibility and material characteristics. In addition, a newly developed reconfigurable automated fiber placement system with adaptive force controlled compaction unit, whose technical characteristics are represented within the optimization framework, and an online thermal imaging system for monitoring fiber placement manufacturing processes are presented. It is shown, how component topologies easily improve and adapt themselves to the corresponding production technology due to returned process knowledge and manufacturing restrictions and hereby avoiding time consuming redesign iterations. The coupling of optimization framework and manufacturing system lead to a self-configuration of automated fiber placement processes and an individually parametrization of the monitoring system for part specific online quality control.
Herwig, Alexander; Groß, Lukas; Serna, Jonathan; Denkena, Berend; Schmidt, Carsten
Entwicklung eines mehrlagigen Inserts für dünnwandige Hochleistungs-CFK- Strukturen Artikel
In: Lightweight Design, Bd. 9, Nr. 1, S. 22-27, 2016, ISSN: 1865-4819.
Abstract | Links | BibTeX | Schlagwörter: Composite Structures, Intrinsic Hybridisation, Multilayer Insert
@article{Herwig2016,
title = {Entwicklung eines mehrlagigen Inserts für dünnwandige Hochleistungs-CFK- Strukturen},
author = {Alexander Herwig and Lukas Groß and Jonathan Serna and Berend Denkena and Carsten Schmidt},
editor = {Wolfgang Siebenpfeifer Springer Vieweg},
doi = {10.1007/s35725-015-0064-7},
issn = {1865-4819},
year = {2016},
date = {2016-01-01},
journal = {Lightweight Design},
volume = {9},
number = {1},
pages = {22-27},
abstract = {Hochbelastete Verbindungen von dünnwandigen Strukturen werden im Flugzeug- und Automobilbau häufig als Klebungen oder als Überlappungsfügung mit Bolzen realisiert. Durch den zunehmenden Einsatz von Faser-Kunstoff-Verbunden (FKV) entsteht der Bedarf neuer Verbingungstechnologien, die ein faser- und belastungsgerechtes Fügen der Strukturen erlauben. Konventionelle Nietverbindungen und eingebrachte Metallstrukturen wie Gewindeeinsätze oder bigHeads bilden eine überprüfbare formschlüssige Verbindung. Die Krafteinteilung erfolgt über die Kontaktflächen der Metallstruktur in die angrenzenden Schichten des Laminats. Typische Ausführungen von Verbindungselementen sind in Bild 1 dargestellt. Das Einbringen dieser Inserts als Fremdkörper in ein Laminat bedingt eine lokale Aufdickung und führt zu einer Störung des Faserverlaufs und damit zu einer Schwächung des Bauteils. Dieser Problematik Multilayer-Inserts (MLI). Der erarbeitete Ansatz verfolgt eine lokale intrinsische Hybridisierung des Laminats bereits während der Ablage der CFK-Einzelschichten durch dünne Metallschichten ersetzt werden.},
keywords = {Composite Structures, Intrinsic Hybridisation, Multilayer Insert},
pubstate = {published},
tppubtype = {article}
}
2015
Deniz, Onur; Horst, Peter; Schmidt, Carsten
In: 11th World Congress on Structural and Multidisciplinary Optimisation, Sydney, 2015.
Abstract | Links | BibTeX | Schlagwörter: Composite Structures, Evolutionary strategies, Surrogate Model
@inproceedings{Deniz2015,
title = {Production-based Multi-criteria Design Optimisation of an Unconventional Composite Fuselage Side Panel by Evolutionary Strategies and a Surrogate Model of Manufacturability Analysis},
author = {Onur Deniz and Peter Horst and Carsten Schmidt},
url = {http://web.aeromech.usyd.edu.au//WCSMO2015/papers/1421_paper.pdf},
year = {2015},
date = {2015-06-07},
booktitle = {11th World Congress on Structural and Multidisciplinary Optimisation},
address = {Sydney},
abstract = {This paper introduces a novel multi-criteria optimisation framework that efficiently combines manufacturing analysis of composite structures with respect to various production criteria such as manufacturability and limitation of process-based material deviations. These criteria include gaps induced by fibre placement systems as well as structural constraints regarding material failure, stability and damage tolerance. Within this optimisation framework, evolutionary algorithms are coupled with an in-house parametric FE-Model generation tool, which exhibits an extensive design scope comprising various unconventional stiffener topologies, evaluates buckling modes and obtains composite specific failure criteria according to multiple load cases.
This work focuses on multi-criteria optimisation of a newly developed lattice-stiffened fuselage panel with novel double-curved stiffeners aiming for minimum weight based on a reference structure. Composite related design parameters such as number of layers and orientations of fibres are efficiently optimized in conjunction with a wide range of geometric parameters by applying a layup table based strategy regarding manufacturable layup combinations.
Within the optimization framework, an interface to the production concept is introduced, which evaluates quantitative information based on manufacturability analysis and estimation of tow gaps according to geometric topology of the stiffeners regarding machine parameters of AFP system. In context of the investigation manufacturability outputs are approximated using radial basis functions in order to increase the optimization efficiency in terms of computation time. Both structural responses and manufacturability values of the each individual are converted into one fitness value generated by the in-house evolutionary algorithm. This fitness evolution leads to more efficiently producible unconventional configurations and adequate mechanical performance with significant weight savings and limited material deviations based on production criteria at the each new generation.
Main characteristics of the optimized new panel are respectively, adaptation of the unconventional stiffener topologies to various loading conditions and innovative window configurations offering considerably large space. The final design is compared with an optimised reference composite panel with the same weight objective under identical loading conditions.},
keywords = {Composite Structures, Evolutionary strategies, Surrogate Model},
pubstate = {published},
tppubtype = {inproceedings}
}
This work focuses on multi-criteria optimisation of a newly developed lattice-stiffened fuselage panel with novel double-curved stiffeners aiming for minimum weight based on a reference structure. Composite related design parameters such as number of layers and orientations of fibres are efficiently optimized in conjunction with a wide range of geometric parameters by applying a layup table based strategy regarding manufacturable layup combinations.
Within the optimization framework, an interface to the production concept is introduced, which evaluates quantitative information based on manufacturability analysis and estimation of tow gaps according to geometric topology of the stiffeners regarding machine parameters of AFP system. In context of the investigation manufacturability outputs are approximated using radial basis functions in order to increase the optimization efficiency in terms of computation time. Both structural responses and manufacturability values of the each individual are converted into one fitness value generated by the in-house evolutionary algorithm. This fitness evolution leads to more efficiently producible unconventional configurations and adequate mechanical performance with significant weight savings and limited material deviations based on production criteria at the each new generation.
Main characteristics of the optimized new panel are respectively, adaptation of the unconventional stiffener topologies to various loading conditions and innovative window configurations offering considerably large space. The final design is compared with an optimised reference composite panel with the same weight objective under identical loading conditions.
Biel, Andreas
Simulative Bauteil- und Prozessoptimierung im Composite Bereich Konferenzbeitrag
In: 1. Niedersächsisches Symposium Materialtechnik, Clausthal-Zellerfeld, 2015.
BibTeX | Schlagwörter: Composite Structures, Draping Simulation
@inproceedings{Biel2015,
title = {Simulative Bauteil- und Prozessoptimierung im Composite Bereich},
author = {Andreas Biel},
year = {2015},
date = {2015-02-13},
booktitle = {1. Niedersächsisches Symposium Materialtechnik},
address = {Clausthal-Zellerfeld},
keywords = {Composite Structures, Draping Simulation},
pubstate = {published},
tppubtype = {inproceedings}
}
2014
Engel, Kevin; Horst, Peter; Hundt, Tobias; Schmidt, Carsten; Denkena, Berend
Effect of manufacturing process induced fiber waviness on mechanical properties of composite structures by example of a prepreg forming process Konferenzbeitrag
In: ECCM16 - 16TH European Conference on Composite Materials, Seville, 2014.
Abstract | BibTeX | Schlagwörter: Composite Structures, Fiber Waviness
@inproceedings{Engel2014,
title = {Effect of manufacturing process induced fiber waviness on mechanical properties of composite structures by example of a prepreg forming process},
author = {Kevin Engel and Peter Horst and Tobias Hundt and Carsten Schmidt and Berend Denkena},
year = {2014},
date = {2014-06-22},
booktitle = {ECCM16 - 16TH European Conference on Composite Materials},
issuetitle = {ECCM16 - 16TH European Conference on Composite Materials},
address = {Seville},
abstract = {In this paper an approach to include the effects of a forming process on preimpregnated fibers into the design of composite structures by analysis of the resulting fiber waviness is presented. Therefore the influence of the forming process and a measurement method for fiber waviness is discussed. Fiber waviness in formed composite parts is characterized by the power spectral density and the resulting fiber angle distribution. This modeled using a discrete inverse fast Fourier transformation. Subsequently the mechanical properties are calculated based on these fiber angle distributions in a finite element analysis. An additional comparative experimental analysis of a specimen manufactured with and without the influence of the forming process is presented. The measured fiber angle distributions are analyzed and resulting first ply failure for both cases is predicted using the presented method.},
keywords = {Composite Structures, Fiber Waviness},
pubstate = {published},
tppubtype = {inproceedings}
}
Deniz, Onur; Horst, Peter; Weber, Patricc; Schmidt, Carsten; Denkena, Berend
Design optimization of an unconventinal cfrp aircraft panel stiffner based on manufacturability criteria of integrated fiber placement processes Konferenzbeitrag
In: 16th European Conference on Composite Materials, Seville, 2014.
Abstract | BibTeX | Schlagwörter: Automated Fiber Placement, Composite Structures, Design Optimization
@inproceedings{Deniz2014,
title = {Design optimization of an unconventinal cfrp aircraft panel stiffner based on manufacturability criteria of integrated fiber placement processes},
author = {Onur Deniz and Peter Horst and Patricc Weber and Carsten Schmidt and Berend Denkena},
year = {2014},
date = {2014-06-22},
booktitle = {16th European Conference on Composite Materials},
address = {Seville},
abstract = {This paper introduces a global optimization methodology that comprises structural analysis in conjunction with manufacturability examination of the aircraft components based on in-house developed automated fiber placement (AFP) system. Target point of the investigation is an unconventional grid stiffened carbon fiber reinforced plastic (CFRP) fuselage panel with additional multi-curved local stabilizers (stiffener peaks) that are located between diagonal grid stiffeners. The optimization task is formulated to reach global minimum weight of the panel under combined loading scenarios with respect to composite material failures, stability and manufacturability of stiffener peaks based on AFP system. Presented methodology solves the multi-disciplinary problem and offers producible unconventional configurations with adequate mechanical performance and weight savings based on production limits and objectives.},
keywords = {Automated Fiber Placement, Composite Structures, Design Optimization},
pubstate = {published},
tppubtype = {inproceedings}
}
Kriglsteiner, Joscha; Horst, Peter; Schmidt, Carsten
Optimization of fiber-reinforced stiffener profiles for aircraft fuselage preliminary structural design Konferenzbeitrag
In: 16th European Conference on Composite Materials, Seville, 2014.
Abstract | BibTeX | Schlagwörter: Composite Structures, Fuselage, Preliminary design, Stiffener Profiles
@inproceedings{Kriglsteiner2014,
title = {Optimization of fiber-reinforced stiffener profiles for aircraft fuselage preliminary structural design},
author = {Joscha Kriglsteiner and Peter Horst and Carsten Schmidt},
year = {2014},
date = {2014-06-22},
booktitle = {16th European Conference on Composite Materials},
address = {Seville},
abstract = {This paper presents a characterization module for stiffener profiles. It is part of a modellig and analysis tool for stiffened structures in aircraft fuselage design. The module offers options to determine mechanical characteristics of a given section such as mass, stiffness, and failure loads for strength and local stability. For the characterization, analytical approaches and the Finite Element Method (FEM) are used. Both ways are presented and the results are compared as part of the verification of the module. Furthermore, how the module can be used for a basic comparison of design concepts is described.},
keywords = {Composite Structures, Fuselage, Preliminary design, Stiffener Profiles},
pubstate = {published},
tppubtype = {inproceedings}
}
Hundt, Tobias; Schmidt, Carsten; Denkena, Berend; Engel, Kevin; Horst, Peter
Variable forming tool and process for thermoset prepregs with simulation verified part quality Artikel
In: Key Engineering Materials, Bd. 611-612, S. 391-398, 2014.
Abstract | BibTeX | Schlagwörter: Composite Structures, Variabel Forming Tool
@article{Hundt2014,
title = {Variable forming tool and process for thermoset prepregs with simulation verified part quality},
author = {Tobias Hundt and Carsten Schmidt and Berend Denkena and Kevin Engel and Peter Horst},
year = {2014},
date = {2014-05-01},
journal = {Key Engineering Materials},
volume = {611-612},
pages = {391-398},
abstract = {In this paper a new variable forming tool concept and associated numerical methods for calculating optimal actuator layout and estimating CFRP part quality are presented. The concept of the tool features a modular design and active control of the forming process to achieve the desired geometry. Initially the laminate is placed on the flat top layer of the forming tool. There it is fixed and compacted using vacuum bagging. After compacting, it is heated up to increase the performance of the forming process using water based tempering of the forming tool’s top layer. The heated laminate is then formed, pulling the tool’s top layer into the desired geometry using the actuators. Finally, the formed laminate is cooled and transferred into a mold for curing. The position of the forming tool’s actuators on the base plates is variable. Numerical optimization in combination with finite element (FE) technologies is utilized, to approximate the tool surface within given error margins, with as few actuators as possible. In addition, results of a numerical method for part quality estimation are shown. The influence of the forming process on mechanical properties due to fiber waviness is taking into account using a self-developed method that includes manufacturing characteristics in FE modeling of the part. The method is based on mathematical descriptions of fiber waviness, which are implemented into a FE model. Therefore a structure discretization assuming perfect fiber orientations is realized and the expected fiber waviness induced by the forming process is applied element-wise.},
keywords = {Composite Structures, Variabel Forming Tool},
pubstate = {published},
tppubtype = {article}
}
Schmidt, Carsten; Schultz, Cedric; Weber, Patricc; Denkena, Berend
In: Composites PArt B: Engineering, Bd. 56, S. 109-116, 2014.
Abstract | Links | BibTeX | Schlagwörter: Automated Fiber Placement, Composite Structures, Eddy Current Testing, Process Monitoring, Quality Assurance
@article{Schmidt2014,
title = {Evaluation of eddy current testing for quality assurance and process monitoring of automated fiber placement},
author = {Carsten Schmidt and Cedric Schultz and Patricc Weber and Berend Denkena},
url = {http://dx.doi.org/10.1016/j.compositesb.2013.08.061},
year = {2014},
date = {2014-01-01},
journal = {Composites PArt B: Engineering},
volume = {56},
pages = {109-116},
abstract = {Standards in energy and cost efficiency are higher the ever especially in the aerospace industry. While structures made from carbon-fiber reinforced plastics (CFRP) show significant advantages in regards to specific strength and lightweight design, further improvements in their production processes are essential in order for CFRP to be competitive in the future. The authors present eddy current (EC) testing as a means for quality assurance (QA) and process monitoring for CFRP parts produced by automatic fiber placement (AFP), which is one the most prevalent production methods in aerospace industry. Eddy current testing shows the potential for highly automated process monitoring that can reduce error correction and cycle time in AFP.},
keywords = {Automated Fiber Placement, Composite Structures, Eddy Current Testing, Process Monitoring, Quality Assurance},
pubstate = {published},
tppubtype = {article}
}
2013
Denkena, Berend; Horst, Peter; Schmidt, Carsten; Behr, Matthias; Krieglsteiner, Joscha
Efficient production of CFRP lightweight structures on the basis of manufacturing considerations at an early design stage Konferenzbeitrag
In: Machining Innovation Conference , Hannover, 2013.
Abstract | BibTeX | Schlagwörter: Aerospace, Composite Structures, Fuselage, Preliminary design
@inproceedings{Denkena2013,
title = {Efficient production of CFRP lightweight structures on the basis of manufacturing considerations at an early design stage},
author = {Berend Denkena and Peter Horst and Carsten Schmidt and Matthias Behr and Joscha Krieglsteiner},
year = {2013},
date = {2013-09-18},
booktitle = {Machining Innovation Conference },
address = {Hannover},
abstract = {Success in development of lightweight structures is determined by the three disciplines of design, materials, and manufacturing. Focusing on design leads to expensive lightweight structures while overrating production makes it hard to reach structural performance goals. The global optimum of structural performance and cost can only be reached if all three disciplines are equally taken into account. It can be observed that this optimum gets increasingly important for major strategic decisions in lightweight construction industry, e.g. the material concept in future aircraft structures: carbon fiber-reinforced plastics (CFRP) vs. aluminum.
While development of metallic structures is industrially performed and broadly researched, fiber-reinforced plastics do present new challenges. Design work with homogeneous and isotropic metallic structures is mainly done on a level of part shape and sizing. For composites, the inner heterogeneous and orthotropic structure has to be engineered as well. Therefore, structure development usually has to deal with a higher number of design parameters, raising the need for simulation tools and optimization algorithms. In addition to more sophisticated design procedures, production planning for composite structures gets more challenging as well. For metallic structures, manufacturing usually starts with semi-finished parts having material properties mostly set as in the final product. The material properties of composites are mainly determined by the manufacturing processes. Properties such as fiber volume fraction or fiber orientation and imperfections like fiber undulations or inclusions are highly dependent on manufacturing. Therefore process stability has a large impact on structural characteristics. Design mostly accounts for the resulting uncertainties with high knock-down factors for assumed material properties, i.e. decreased lightweight potential.},
keywords = {Aerospace, Composite Structures, Fuselage, Preliminary design},
pubstate = {published},
tppubtype = {inproceedings}
}
While development of metallic structures is industrially performed and broadly researched, fiber-reinforced plastics do present new challenges. Design work with homogeneous and isotropic metallic structures is mainly done on a level of part shape and sizing. For composites, the inner heterogeneous and orthotropic structure has to be engineered as well. Therefore, structure development usually has to deal with a higher number of design parameters, raising the need for simulation tools and optimization algorithms. In addition to more sophisticated design procedures, production planning for composite structures gets more challenging as well. For metallic structures, manufacturing usually starts with semi-finished parts having material properties mostly set as in the final product. The material properties of composites are mainly determined by the manufacturing processes. Properties such as fiber volume fraction or fiber orientation and imperfections like fiber undulations or inclusions are highly dependent on manufacturing. Therefore process stability has a large impact on structural characteristics. Design mostly accounts for the resulting uncertainties with high knock-down factors for assumed material properties, i.e. decreased lightweight potential.