ETH Research DatabaseProject Summary

Fast and robust joining process for aerospace components by localheating of paste adhesives

1) Creation date of the summary: 03.12.2015

2) Record ID: 26732

3) Last update: 03.02.2015

4) Project status: Completed (01.09.2009 - 31.03.2014)

5) Organizational unit: Departement Maschinenbau und Verfahrenstechnik, Institut für Mecha-nische Systeme (IMES), Ermanni, Paolo, permanni@ethz.ch, LZ=03507

6) Project leader(s):- Ermanni, Paolo, permanni@ethz.ch, Dep. Maschinenbau und Verfahrenstechnik, Inst. f.

Design, Mat. und Fabrikation

7) ETH researcher(s):- Sánchez Cebrián, Alberto, salberto@inspire.ethz.ch, Dep. Maschinenbau und Verfahrens-

technik, Inst. f. Design, Mat. und Fabrikation

8) External researcher(s): no entry

9) Funding source(s):- EU

10) Partner organizations: no entry

11) Short Summary: The goal of the research project is to investigate original approaches ai-ming at optimizing the assembly design and the process parameters for robust fast joining of aero-space components by paste adhesives.

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12) Keywords: Engineering Sciences

13) Project description:Bonding is a well-suited technique for joining carbon fiber reinforced polymer (CFRP) structures.Advantages of adhesive bonding include the possibility to avoid load peaks, as they often appear inriveted joining systems and to not require drilling in load carrying structures. Furthermore bondedjoints are weight efficient and have potential for integration of functions.The bonding process includes a number of process steps, one of them being curing of the adhesivesystem. There are different ways to initiate curing, e.g. heat, UV, humidity, X-ray. Today the curingof the majority of high performance adhesive systems is initiated by heat. In order to cope withthe thermal requirements of aerospace structures, adhesive systems typically require high curingtemperatures. High temperature reduces the curing time, but on the other hand increases the risk ofthe adhesive system degradation. Thus optimization of the curing process needs to leverage curingtime and temperature. Curing cycles for adhesive systems nowadays are normally defined based ondatasheet information without considering the local design of the bonded joint. This usually leadsto a safe and robust process with long cycle times.Adhesive systems for aerospace applications are available in film form or as a paste. Film adhesivesuse a support carrier to control the minimum thickness between the bonding partners and thereforeguarantee a good and reproducible quality of the bonded joint. The drawback of this technologyis related to the very high requirements in terms of geometrical accuracy of the components tobe bonded. Curing typically takes place in autoclaves or ovens. Normally the entire assembly isheated.This research project is concerned with paste adhesive technology for aerospace applications. Amajor advantage of paste adhesives compared to film adhesives is the possibility to compensategeometrical tolerances of the bonding partners thus allow for more simple and cost effective ma-nufacturing routes. Paste adhesives have successfully been applied for structural bonding in nonaerospace field; typical examples are windows bonded to the vehicle structure. Yet aerospace app-lications in primary structures are still missing due to a lack of confidence in ”design for reliablebonding” and in quality control of the bonding process as well as the necessity of small toleran-ces in the bonded joint. Applicability of paste adhesives in aerospace industry is matter of intenseefforts because of the potential weight savings compared to traditional riveted joints and cost sa-vings compared to film adhesive joints. Our original approach is considering the complex set ofrequirements resulting from the application of paste adhesive technologies in the aircraft industrynamely ecological, quality and economical criteria for robust and reliable processing.This research project is a part of SClean SkyŠ Joint Technology Initiative, in the frame of greendesign, working with industrial partners such as RUAG Switzerland Ltd and Huntsman AdvancedMaterials GmbH.The goal of the research project is to investigate original approaches aiming at optimizing theassembly design and the process parameters for robust fast joining of aerospace components bypaste adhesives. To achieve this target, we plan to investigate a methodology for fast, robust andselective adhesiveŠs curing. The research approach is considering a number of challenging topicsincluding:T The investigation of appropriate technologies for selective heating and process control.T The development of a multi-physics design environment (simulation tool) considering structuralmechanics, thermal and chemical effects.T The experimental validation of models and technology to:

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o Verify the methodology on an appropriate demonstrator.o Define a processing window.o Optimize bonding partners, bonding system and assembly tool considering ecological and eco-nomical impact on appropriate demonstrators.o Provide design guidelines.T The modification and optimization of the adhesive with regard to magnetic or electrical heating.The PhD research is divided in four major activities, which are briefly described below:1. Local heating concepts: Compare different methods for fast local heating of bonded assemblies,evaluate under ecological and economical criteria and select one method for further investigations.2. Modeling and simulation: Investigate the major parameters and limits which affect for joiningof two components by paste adhesives without heating the complete assembly.3. Process optimization: Establish a method to define optimal assembly design (bonding partners,bonding system and assembly tool) and process parameters for fast and high quality joining of twocomponents by paste adhesives without heating the complete assembly.4. Demonstrator: Verify the method on an aerospace demonstrator.

14) Popular description: no entry

15) Graphics:

Kinetics of paste adhesive

ETH Zürich

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Project

ETHZ

Simulation tool

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ETHZ

Effect of particles to improve induction heating

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ETHZ

16) Publications:- Sánchez Cebrián, Alberto; Basler, Ralf; Klunker, Florian; Zogg, Markus. 2014-01-01. Ac-

celeration Of The Curing Process Of A Paste Adhesive For Aerospace Applications ConsideringCure Dependent Void Formations. International journal of adhesion and adhesives, Elsevier, (48),

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Kidlington, 51-58.- Sánchez Cebrián, Alberto; Basler, Ralf; Zogg, Markus. 2012-01-01. Multistep heating to

optimize curing process of a paste adhesive. European Society for Composite Materials.- Sánchez Cebrián, Alberto; Klunker, Florian; Zogg, Markus. 2014-01-01. Simulation of the

cure of paste adhesives by induction heating. Journal of composite materials, Sage, (12/ 48), Thou-sand Oaks, CA, 1459-1474.

- Sánchez Cebrián, Alberto; Lucchini, Stefano; Zogg, Markus; Ermanni, Paolo. 2011-01-01.Effect of different surface treatments on mechanical properties of CFRP bonded joints. SAMPEEurope Conference Management, Riehen, 393-400.

- Sánchez Cebrián, Alberto; Moser, Patrick; Zogg, Markus; Ermanni, Paolo. 2012-01-01.Paste adhesive modification for induction curing. Society for the Advancement of Material andProcess Engineering.

- Sánchez Cebrián, Alberto; Zogg, Markus; Ermanni, Paolo. 2013-01-01. Beschleunigungder Aushärtung von pastösen Epoxidharzklebstoffen durch variotherme Prozessführung mittelsInduktion. Fraunhofer-Institut für Fertigungstechnik und Angewandte Materialforschung IFAM;adhäsion KLEBEN&DICHTEN.

- Sánchez Cebrián, Alberto; Zogg, Markus; Ermanni, Paolo. 2013-01-01. Fast and RobustJoining Process for Aerospace Components by Local Heating of Paste Adhesives. SAMPE Euro-pe.

- Sánchez Cebrián, Alberto; Zogg, Markus; Ermanni, Paolo. 2011-01-01. Indicators for opti-mizing cure temperature of paste adhesives. 18th International Conference on Composite Materials(ICCM18).

- Sánchez Cebrián, Alberto; Zogg, Markus; Ermanni, Paolo. 2013-01-01. Methodology foroptimization of the curing cycle of paste adhesives. International journal of adhesion and adhesi-ves, Elsevier, (1/ 40), Kidlington, 112-119.

17) Links to important web pages:- http://www.cleansky.eu

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