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Automated layup and forming of prepreg laminates
Linköping University, Department of Management and Engineering, Manufacturing Engineering. Linköping University, Faculty of Science & Engineering.ORCID iD: 0000-0001-8015-3039
2017 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Composite materials like carbon fiber-reinforced polymers (CFRPs) present highly appealing material properties, as they can combine high strength with low weight. In aerospace applications, these properties help to realize lightweight designs that can reduce fuel consumption. Within the aerospace industry, the use of these types of materials has increased drastically with the introduction of a new generation of commercial aircraft. This increased use of CFRP drives a need to develop more rational manufacturing methods.

For aerospace applications, CFRP products are commonly manufactured from a material called prepreg, which consists of carbon fibers impregnated with uncured polymer resin. There are two dominant manufacturing technologies for automated manufacturing using prepreg, automated tape layup and automated fiber placement. These two technologies are not suitable for all types of products, either due to technical limitations or a combination of high investment costs and low productivity. Automation alternatives to the two dominant technologies have been attempted, but have so far had limited impact. Due to the lack of automation alternatives, manual manufacturing methods are commonly employed for the manufacturing of complex-shaped products in low to medium manufacturing volumes.

The research presented in this thesis aims to explore how automated manufacturing systems for the manufacturing of complex CFRP products made from prepreg can be designed so that they meet the needs and requirements of the aerospace industry, and are suitable for low to medium production volumes. In order to explore the area, a demonstrator-centered research approach has been employed. A number of demonstrators, in the form of automated manufacturing cells, have been designed and tested with industrial and research partners. The demonstrators have been used to identify key methods and technologies that enable this type of manufacturing, and to analyze some of these methods and technologies in detail. The demonstrators have also been used to map challenges that affect the development of enabling methods and technologies.

Automated manufacturing of products with complex shapes can be simplified by dividing the process into two steps. Thin layers of prepreg are laid up on top of each other to form flat laminates that are formed to the desired shape in subsequent forming operations. The key methods and technologies required to automate such a system are methods and technologies for automated prepreg layup, the automated removal of backing paper and the forming of complex shapes. The main challenges are the low structural rigidity and tacky nature of prepreg materials, the extensive quality requirements in the aerospace industry and the need for the systems to handle a wide array of prepreg shapes.

The demonstrators show that it is possible to automate the manufacturing of complexshaped products using automated layup and forming of prepreg laminates. Tests using the demonstrators indicate that it is possible to meet the quality requirements that apply to manual manufacturing of similar products.

Abstract [sv]

Polymera kolfiberkompositer erbjuder en eftertraktad kombination av låg vikt och högstyrka som kan bidra till lättviktskonstruktioner som t.ex. kan leda till bränslebesparingarför passagerarflygplan. Inom flygindustrin har användningen av denna materialtyp ökatkraftigt med introduktionen av en ny generation flygplan som till mer än hälften består avkompositmaterial. Den ökade användningen av polymera fiberkompositer medför ett ökatbehov av rationella produktionsmetoder.

Inom flygindustrin tillverkas ofta polymera kolfiberkompositprodukter av så kallatprepreg-material som består av kolfibrer impregnerade med en plast. Det finns tvåhuvudalternativ för automatisk tillverkning av prepreg-baserade produkter, automatisktejpläggning eller automatisk fiberplacering. De två alternativen har tekniskabegränsningar och är förknippade med mycket höga investeringskostnader vilket gör attdet finns produkter som de inte kan tillverka eller som inte är kostnadseffektiva atttillverka med dessa två metoder. Andra automatiska alternativ har utvecklats, men har intenått någon större industriell implementering. Bristen på automatiseradetillverkningsalternativ leder till att produkter med komplex form, och som tillverkas i småoch medelstora volymer ofta tillverkas manuellt.

Forskningen som presenteras i denna avhandling syftar till att undersöka hur automatiskatillverkningsceller för tillverkning av polymera kolfiberkompositprodukter med komplexform kan utformas så att de uppfyller de krav som gäller för tillverkningen av produkterför flygindustrin och är lämpliga för låga och medelhöga tillverkningsvolymer. Endemonstratorcentrerad forskningsmetod har använt för att utforska området och ett flertaldemonstratorer har byggts och testats tillsammans med partners från industrin och andraforskningsorganisationer. Demonstratorerna, som är kompletta tillverkningsceller, haranvänts för att identifiera metoder och utrustning som är nödvändiga att utveckla för attautomatisera denna typ av tillverkning och för att undersöka några metoder och tillhörandeutrustning mer i detalj. Demonstratorerna har också använts för att kartlägga faktorer sompåverkar hur metoder och utrustning utformas.

Automatisk tillverkning av produkter med komplex form kan förenklas genom att delaupp tillverkningen i två steg. Först läggs prepreg-ark ihop till ett laminat som formas tillproduktens form i ett efterföljande steg. För att automatisera denna typ av tillverkningbehöver nyckelmetoder och nyckelutrustning för hopläggning av laminat, borttagning avskyddspapper samt formning av laminat till komplexa former utvecklas. Viktiga faktorersom påverkar utformningen av tillverkningscellerna är prepreg-materialens låga styvhetoch klibbiga yta, de höga kvalitetskrav som gäller för tillverkning avflygplanskomponenter samt att systemen måste hantera en stor mängd olikformadeprepreg-ark. Demonstratorerna visar att det är möjligt att automatisera tillverkningen avpolymera kolfiberprodukter med komplex form genom automatisk uppläggning ochformning av plana laminat. Tester med demonstratorerna pekar på att det är möjligt atttillverka produkterna i enlighet med de kvalitetskrav som finns för manuell tillverkningav liknande produkter.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2017. , 131 p.
Series
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 1858
National Category
Production Engineering, Human Work Science and Ergonomics Aerospace Engineering Composite Science and Engineering
Identifiers
URN: urn:nbn:se:liu:diva-137488DOI: 10.3384/diss.diva-137488ISBN: 978-91-7685-510-2 (print)OAI: oai:DiVA.org:liu-137488DiVA: diva2:1096316
Public defence
2017-06-16, C3, C-huset, Campus Valla, Linköping, 10:15 (Swedish)
Opponent
Supervisors
Available from: 2017-05-17 Created: 2017-05-17 Last updated: 2017-05-17Bibliographically approved
List of papers
1. Composite Manufacturing: How Improvement Work Might Lead to Renewed Product Validation
Open this publication in new window or tab >>Composite Manufacturing: How Improvement Work Might Lead to Renewed Product Validation
2012 (English)In: Proceedings of the 5th International Swedish Production Symposium / [ed] Mats Björkman, 2012, 505-513 p.Conference paper, Published paper (Refereed)
Abstract [en]

High-performance polymer composites are mainly used in applications where the benefits of high strength and low weight justify the high material and manufacturing costs. Many of these applications are found today in the aerospace, space and defense industries. Most of today’s commonly used manufacturing methods within this area are highly labor intensive. Furthermore, the quality requirements from the customers require a high level of process control. The purpose of this paper is to explore how changes that are introduced in order to improve productivity in a manufacturing system are managed, particularly with regard to who takes the decision to implement a change and how a change is validated. The study is based on qualitative interviews performed at several companies that manufacture composite components for the aerospace, space and defense sectors. The findings show that the responsibility for deciding to implement a change and the need for validating it are based on many diverse and interconnected factors. Therefore, it is difficult to construct guidelines for early assessment of the scope and cost of a proposed change. Hence each individual change request must be evaluated on its own. The study also shows that the validation process can be adapted to a level that is based on the type of change. In addition, it highlights that control over process parameters in manufacturing is essential.

Keyword
composite manufacturing, validation, change request management
National Category
Production Engineering, Human Work Science and Ergonomics
Identifiers
urn:nbn:se:liu:diva-85268 (URN)978-91-7519-752-4 (ISBN)
Conference
5th International Swedish Production Symposium (SPS 2012), 6-8 November 2012, Linköping, Sweden
Available from: 2012-11-14 Created: 2012-11-14 Last updated: 2017-05-17
2. Automated Removal of Prepreg Backing Paper - A Sticky Problem
Open this publication in new window or tab >>Automated Removal of Prepreg Backing Paper - A Sticky Problem
2013 (English)In: Proceedings of the SAE 2013, Aerotech Congress and Exhibition, 24th-26th September 2013, Montreal,Canada, 2013Conference paper, Published paper (Refereed)
Abstract [en]

Automated solutions for manufacturing composite products based on prepreg often imply Automatic Fiber Placement or Automatic Tape Laying. These systems are generally associated with huge investments. For certain manufacturing applications it is interesting to investigate alternatives to find simpler and less costly automation. One example of an automated system could be the use of a standard industrial robot to pick single prepreg plies from an automated cutting machine and stack them to form a plane laminate. This paper is based on a case illustrating a product from the aircraft manufacturing industry. The case will demonstrate a pick and place concept on a general level and illustrate challenges that must be solved. The challenge selected to be the main focus for this paper is an automated process for backing paper removal. A literature review of different gripping technologies reveals several interesting technologies, and the most promising are tested for backing paper removal. The tests show that an automated removal process can be designed by using standard vacuum grippers in combination with mechanical clamping grippers. In order to lift the backing paper with a vacuum gripper an initial separation between the backing paper and prepreg is needed. This separation is most easily mechanically induced by bending the material. The proposed solution for automatic backing paper removal can be integrated in a manufacturing cell for manufacturing of the studied product.

Keyword
composite manufacturing, automation, prepreg, gripping technology
National Category
Production Engineering, Human Work Science and Ergonomics
Identifiers
urn:nbn:se:liu:diva-99344 (URN)10.4271/2013-01-2289 (DOI)
Conference
SAE 2013 Aerotech Congress and Exhibition, September 24-26, 2013, Montréal, Quebec, Canada
Note

SAE Technical Paper 2013-01-2289

Available from: 2013-10-16 Created: 2013-10-16 Last updated: 2017-05-17Bibliographically approved
3. Automation of Composite Manufacturing Using Off-the-shelf Solutions, Three Cases from the Aerospace Industry
Open this publication in new window or tab >>Automation of Composite Manufacturing Using Off-the-shelf Solutions, Three Cases from the Aerospace Industry
2015 (English)In: Proceedings of the 20th International Conference on Composite Materials, 2015Conference paper, Published paper (Other academic)
Abstract [en]

With an increased use of composite materials follows a need for rational, cost-efficient manufacturing processes. This paper explores how off-the-shelf solutions, developed for other purposes than composite manufacturing, can be used to build systems for automated composite manufacturing. Three demonstrators, each of them dealing with a specific type of material and all of them representing different manufacturing technologies for automated composite manufacturing, are presented and analyzed to find aspects that affect the ability to use off-the-shelf solutions. The three demonstrators target low to medium manufacturing volumes of complex products and they have been developed in collaboration with industrial partners within the aerospace industry. The conclusions drawn from the development of the demonstrators are that it is technically feasible to use off-the-shelf solutions in the three cases while adhering to the high quality standards of the industry. Furthermore three groups of aspects, quality aspects, product aspects and system aspects, which affect the ability to use off-the-shelf solutions for automated composite manufacturing, are identified.

Keyword
composite manufacturing, automation, off-the-shelf, aerospace
National Category
Production Engineering, Human Work Science and Ergonomics
Identifiers
urn:nbn:se:liu:diva-120300 (URN)
Conference
ICCM20 - The 20th International Conference on Composite Materials, 19-24th July 2015, Copenhagen Denmark
Available from: 2015-07-27 Created: 2015-07-27 Last updated: 2017-05-17
4. Low-cost Automation for Prepreg Handling - Two Cases from the Aerospace Industry
Open this publication in new window or tab >>Low-cost Automation for Prepreg Handling - Two Cases from the Aerospace Industry
2016 (English)In: SAE International Journal of Materials and Manufacturing, ISSN 1946-3979, Vol. 9, no 1Article in journal (Refereed) In press
Abstract [en]

With an increased use of composite materials within the aerospace industry follows a need for rational and cost-effective methods forcomposite manufacturing. Manual operations are still common for low to medium manufacturing volumes and complex products.Manual operations can for example be found in material handling, when picking prepreg plies from a cutter table and stacking them toform a plane laminate in preparation for a subsequent forming operation. Stacking operations of this kind often involves a greatnumber of different ply geometries and removal of backing paper and other protecting materials like plastic. In this paper two differentdemonstrator cells for automated picking of prepreg plies and stacking of plane laminates are presented. One demonstrator is utilizinga standard industrial robot and an advanced end-effector to handle the ply variants. The other demonstrator is using a dual arm robotwhich allow for simpler end-effector design. In combination with a previously developed system for automated removal of backingpapers both systems have shown to be capable of automatically picking prepreg plies from a plane surface and stack them to generate aflat multistack laminate. The dual arm approach has shown advantageous since it result in simpler end-effector design and a successivelay down sequence that result in good adhesion between the plies in the laminate.

Place, publisher, year, edition, pages
Warrendale, USA: SAE International, 2016
Keyword
Composite, Manufacturing, Automation, Low-cost, Prepreg
National Category
Production Engineering, Human Work Science and Ergonomics
Identifiers
urn:nbn:se:liu:diva-121602 (URN)10.4271/2015-01-2606 (DOI)
Available from: 2015-09-28 Created: 2015-09-28 Last updated: 2017-05-17Bibliographically approved
5. Robot-Forming of Prepreg Stacks ‐ Development of Equipment and Methods
Open this publication in new window or tab >>Robot-Forming of Prepreg Stacks ‐ Development of Equipment and Methods
Show others...
2016 (English)In: Proceedings of the 17th European Conference on Composite Materials (ECCM17), 2016Conference paper, Published paper (Other academic)
Abstract [en]

Within the aerospace industry the manufacturing of composite components with complex shapes, such as spars, ribs and beams are often manufactured using manual layup and forming of prepreg material. Automated processes for prepreg layup and efficient forming techniques like vacuum forming are sometimes difficult to employ to these type of products due to technical limitations. This paper describes the development of tools and the forming sequence needed to automate sequential forming of a complex shape using an industrial robot. Plane prepreg stacks are formed to the final shape using a dual-arm industrial robot equipped with rolling tools. Tests show that the developed tools and the employed sequence can be used to form stacks to the desired shape with acceptable quality.

National Category
Production Engineering, Human Work Science and Ergonomics
Identifiers
urn:nbn:se:liu:diva-129925 (URN)
Conference
ECCM17 - 17th European Conference on Composite Materials 26-30th June 2016, Munich, Germany
Available from: 2016-07-01 Created: 2016-07-01 Last updated: 2017-05-17Bibliographically approved

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