25.2.1-R1 DYNAMIC STRENGTH TESTING OF PERFORATED STEEL – GRP DOUBLE LAP JOINTS

R.BRAMBLEBY (IMPERIAL COLLEGE), L.LOUCA, SE.MOURING

This paper presents some initial results investigating the tensile strength of steel to GRP double lap joints comparing pseudo static strength with dynamic strength and comparing joints that have non-perforated steel plates with joints that have perforated steel plates.

25.2.1-R2 PSEUDO-DUCTILITY BY FRAGMENTATION OF CENTRAL UNIDIRECTIONAL PLIES IN THIN CFRP ANGLE-PLY LAMINATES

J.FULLER (UNIVERSITY OF BRISTOL), M.JALALVAND, MR.WISNOM

Pseudo-ductile metal-like tensile stress-strain responses with 700 MPa ”yield stress” plateau and 4.0% failure strain have been achieved experimentally using thin-ply carbon-epoxy prepreg and [±26n/0]s (n = 8, 10) layups. Failure analysis shows a gradual failure of fragmentation and delaminations.

25.2.1-R3 PROPERTIES TESTING OF LIGHTWEIGHT COMPOSITES BASED ON HEMP HURDS

I.SCHWARZOVA (TECHNICAL UNIVERSITY OF KOSICE, FACULTY OF CIVIL ENGINEERING), N.STEVULOVA, J.CIGASOVA, E.TERPAKOVA, J.JUNAK et al.

The investigation of physical and mechanical properties of the lightweight composites based on hemp hurds (3 different mean particle length) as a filler and two alternative binders such as MgO-cement and hydrated lime with cement addition after hardening is given.

25.2.1-R4 PREPREG LAY-UP TECHNOLOGY FOR MANUFACTURING OF LATTICE STRUCTURE FUSELAGE SECTIONS

J.MACK (INSTITUT FUER VERBUNDWERKSTOFFE GMBH), O.MCGERGOR, P.MITSCHANG

The manufacturing of isogrid lattice structures for a fuselage section with the AFP process was evaluated. Different designs for rib crossing points are proposed and experimentally analyzed. Solutions for convex as well as concave tooling concepts were tested

25.2.1-R5 EXPLOITING CARBON NANOTUBE NETWORKS FOR DAMAGE ASSESSMENT OF STRUCTURAL COMPOSITES

A.BALTOPOULOS, N.POLYDORIDES, L.PAMBAGUIAN, A.VAVOULIOTIS, V.KOSTOPOULOS (APPLIED MECHANICS LABORATORY - UNIVERSITY OF PATRAS)

A novel approach for damage inspection of composite structures utilizing carbon nanotubes networks is investigated. Electrical Resistance Tomography is experimentally applied to measure changes in the potential fields and deliver electrical conductivity change maps, used for identifying and locating damage.

25.2.1-R6 STIFFENER DEBONDING DETECTION MONITORING THE RESIDUAL STRAIN FIELD USING A DISTRIBUTED SENSING TECHNIQUE

A.FERNÁNDEZ-LÓPEZ (UPM-ETSIA), A.LOZANO-MARTIN, A.GÜEMES

Stiffener debonding introduces changes in the close strain field that can be easily detected using distributed sensing based on Rayleigh scattering. This technique allows performing delamination detection by one single fully sensitive fiber.

25.2.1-R7 MULTIFUNCTIONAL SANDWICH STRUCTURE FOR ELECTROMAGNETIC ABSORPTION AND MECHANICAL PERFORMANCES.

P.BOLLEN (UNIVERSITÉ CATHOLIQUE DE LOUVAIN), N.QUIÉVY, C.BAILLY, I.HUYNEN, T.PARDOEN

An architectured material is developed towards an optimum combination of structural and electromagnetic absorption performances. It consists of an hexagonal metallic honeycomb filled with a composite polymer/carbon nanotube foam. This hybrid is used as core of sandwich panels with two EM transparent face-sheets.

25.2.2-R1 FAILURE ANALYSIS OF IMPACT-DAMAGED / HYGROTHERMALLY AGED FIBER-REINFORCED POLYMER MATRIX COMPOSITE JOINTS SUBJECTED TO BEND LOADING

J.TARPANI (UNIVERSITY OF SAO PAULO), C.CASTRO, SG.PICKERING, D.ALMOND

Resistance-welded thermoplastic and adhesive-bonded thermosetting composite joints were mechanically compared under four-point-bend loading in pristine and after 10 J impact and/or hygrothermally ageing conditions. Failure analysis determined main operating failure mechanisms and developed fracture types in macro and microscopic levels.

25.2.2-R2 DAMAGE DEVELOPMENT AND STIFFNESS REDUCTION IN LAMINATES UNDER OUT-OF-PLANE LOADING

J.VARNA (LULEA UNIVERSITY OF TECHNOLOGY), A.PUPURS, M.LOUKIL, D.MATTSSON

Approach based on CLT and effective stiffness of damaged layer is suggested for bending stiffness determination of laminate with cracks in 90-layers. The effective stiffness of layer with cracks is back-calculated comparing in-plane stiffness of laminates with and without damage.

25.2.2-R3 DEVELOPMENT OF COMPOSITES FROM EPOXY RESINS AND BIOPOLYMERS

S.SILBERNAGEL-DONATH, A.WÜNSCHEL, U.ARNOLD (KARLSRUHE INSTITUTE OF TECHNOLOGY)

Epoxy resin-biopolymer formulations (biopolymer = lignin, cellulose, starch) were prepared and cured with isophorone diamine. The resulting materials exhibit promising characteristics, even with high biopolymer contents. Epoxy resin-lignin formulations were identified, which could be cured without any additional hardener.

25.2.2-R4 LATTICE COMPOSITE STRUCTURE DEVELOPMENT FOR SMALL AIRCRAFT; WASIS

R.CORDERO (CIDAUT), M.AVERSANO

An introduction to the EU funded research project WASIS (Wafer design Approach for Safety Increasing in worst case Situations and joints minimizing) is given in this paper, including work performed and results obtained by the whole project consortium

25.2.2-R5 MAPPING TECHNIQUE BASED ON ELECTRICAL MEASUREMENTS FOR MONITORING THE INTEGRITY OF COMPOSITE PATCH REPAIR IN AERONAUTICAL STRUCTURES

A.BALTOPOULOS (APPLIED MECHANICS LABORATORY - UNIVERSITY OF PATRAS), A.VAVOULIOTIS, V.KOSTOPOULOS

A technique was formulated and applied to map 1D distributed electrical resistance measurements to damage inspection maps. The technique was applied to a composite patch repair of an aeronautical aluminium component. Results were correlated to IR thermography and visual inspection

25.2.2-R6 MULTISCALE COMPOSITES WITHIN HEALTH-MONITORING CAPABILITIES.

R.VOLPONI (CIRA ITALIAN AEROSPACE RESEARCH CENTRE), P.SPENA, F.DE NICOLA, A.GRILLI

An efficient solution to integrate an epoxy resins charged with carbon nanotubes into a carbon fiber composites are been developed, achieving a multiscale carbon fiber composite. Mechanical and health-monitoring capabilities of multiscale composites are been evaluated

25.2.2-R7 SURFACE MODIFICATION OF ADVANCE FIBERS TO MANUFACTURE MULTIFUNCTIONAL COMPOSITES

A.JIMÉNEZ-SUÁREZ (UNIVERSIDAD REY JUAN CARLOS), M.CAMPO, S.GONZÁLEZ, M.SÁNCHEZ, A.UREÑA

Addition of CNT onto the carbon fiber fabric prior to the resin infiltration is an alternative to the incorporation of the nanoreinforcement to thermoset matrix. This method avoids filtration and viscosity problems leading to improved electrical an interlaminar properties

25.2.3-R1 A PRACTICAL APPROACH TO USE SINGULAR STRESS STATES IN THE DESIGN OF COMPOSITE ADHESIVE JOINTS

A.SOLER, A.BARROSO (UNIVERSITY OF SEVILLE), V.MANTIČ, F.PARÍS

The use of stress singularities for the failure initiation prediction of adhesively bonded joints with composite materials is addressed by means of simplified beam models allowing to calculate the Generalized Stress Intensity Fcators of the critical points where failure initiates.

25.2.3-R2 INVESTIGATING THE DAMAGE MECHANISMS AND THEIR EFFECTS ON THE NOTCH SENSITIVITIES OF CROSSPLY CFRP LAMINATES UNDER UNIAXIAL LOADING

JL.TAN (UNIVERSITY OF CAMBRIDGE), NA.FLECK, V.DESHPANDE, RS.CHOUDHRY, K.ESAKI et al.

Experiments were performed to investigate the fracture behaviour of CFRP laminates under uniaxial loading. The subcritical damage mechanisms that developed prior to failure were seen to have a profound effect on the strength and notch sensitivities of the laminate specimens.

25.2.3-R3 EFFECT OF ROUGHNESS ON THE INTERFACE IN NATURAL FIBRE COMPOSITES: PHYSICAL ADHESION AND MECHANICAL INTERLOCKING

C.FUENTES (KULEUVEN (UNIVERSITY OF LEUVEN)), G.BRUGHMANS, N.TRAN, C.DUPONT-GILLAIN, I.VERPOEST et al.

The fibre-matrix interfacial-bond-strength was characterized by the critical local value of interfacial-shear and radial-normal stresses at the moment of crack-initiation. Pull-out and XPS techniques were used to study the influence of rough natural fibre surfaces on the interface of thermoplastic-composites

25.2.3-R4 EXPERIMENTAL STUDY OF BUCKLING PROPERTIES OF COMPOSITE LATTICE STRUCTURES FOR LAUNCHER APPLICATION

K.TERASHIMA (JAPAN AEROSPACE EXPLORATION AGENCY / JAXA), T.KAMITA, T.AOKI, T.YOKOZEKI, G.KIMURA et al.

Experimental approach for evaluation of buckling properties for various composite lattice structures is described. We conducted the compressive tests to understand the buckling properties for cylindrical lattice shells with and without outer skin, and also conical shell.

25.2.3-R5 DEVELOPMENT OF MULTI-FUNCTIONAL AEROSPACE STRUCTURES USING CNT-MODIFIED COMPOSITE PRE-PREG MATERIALS

A.VAVOULIOTIS (APPLIED MECHANICS LABORATORY - UNIVERSITY OF PATRAS), G.SOTIRIADIS, C.KOSTAGIANNAKOPOULOU, V.KOSTOPOULOS, J.CINQUIN et al.

The introduction on nanotechnology in the field of composites has opened new horizons towards offering unique capabilities for the on-demand tuning of the material properties. This paper reviews various technologies developed towards this direction under ELECTRICAL project.

25.2.3-R6 A TECHNIQUE FOR IN-SITU HEALTH MONITORING OF LARGE POLYMER COMPOSITE STRUCTURES MADE OF CARBON FIBERS AND CARBON NANOTUBE NETWORKS

S.HOA (CONCORDIA UNIVERSITY), SV.HOA

A novel and practical technique is developed to detect, locate and quantify damages in large polymer composite structures made of carbon fibers and carbon nanotube networks.

25.2.3-R7 INTERFACIAL SHEAR STRENGTH OF CARBON NANOTUBES GRAFTED CARBON FIBER/EPOXY

K.NAITO (NATIONAL INSTITUTE FOR MATERIALS SCIENCE)

The interfacial shear strength and fracture behavior of carbon nanotubes (CNT)-grafted polyacrylonitrile (PAN)-based single carbon fiber/epoxy was investigated.

25.2.4-R1 TOWARD A NUMERICAL CONCEPTION OF A TECHNOLOGICAL EVALUATOR FOR COMPOSITE STRUCTURAL REPAIR: SHEAR CHARACTERIZATION

A.CERISIER (CLEMENT ADER INSTITUTE), L.CROUZEIX, F.COLLOMBET, YH.GRUNEVALD

A bonded repair evaluation is proposed through the study of the interface behaviour. This paper follows three steps of the work: non-standard shear tests, a light 2D modelling and the validation of a failure criterion form

25.2.4-R2 DAMAGE OF LAMINATED COMPOSITES FOR VARIOUS MECHANICAL LOADS

C.HOCHARD (LABORATORY OF MECHANICS AND ACOUSTICS)

A model defined on the ply scale to describe the rupture in the fibre direction for statics and fatigue loadings was proposed. This model is based on a reduction of strength in the fibre direction depending on the transverse damage.

25.2.4-R3 STRAIN RATE DEPENDENCE ON TENSILE PROPERTIES FOR BAMBOO FIBER THERMOPLASTIC POLYMER COMPOSITES

J.NODA (YAMAGUCHI UNIVERSITY), Y.TAMURA, K.GODA

The strain rate dependence on mechanical properties of bamboo/polypropylene composites with various fiber weight contents was investigated. The visco-elasticity and visco-plasticity as well as the plastic strain hardening on the stress-strain relations were estimated using the modified G’Sell-Jonas phenomenological model.

25.2.4-R4 DESIGN AND ANALYTICAL ANALYIS OF AN ANISOGRID PREPREG STRUCTURE CONCEPT

S.NIEMANN (GERMAN AEROSPACE CENTRE), R.WAGNER, C.HÜHNE

This paper reports on results of conceptual design phase, aimed at development of a new anisogrid concept for aircraft fuselages. The weight saving potential is analyzed in comparison with an orthogonal stiffened skin structure, satisfying requirements of airworthiness for airframes.

25.2.4-R5 THERMAL, RHEOLOGICAL AND ELECTRICAL CHARACTERIZATION OF MWCNTS/EPOXY MATRICES FOR AN INNOVATIVE SPRAY PROCESS

M.FOGEL (EADS INNOVATION WORKS GERMANY), P.PARLEVLIET, M.GEISTBECK, P.OLIVIER, É.DANTRAS

Graduated in Material Science and Engineering. Research Engineer at Airbus Group Innovations in Munich, Germany. PhD Candidate at the University of Toulouse, France. Research focus: Nanocomposites, Electrical conductivity of composite materials, Damage Tolerance improvement.

25.2.4-R6 DAMAGE EVOLUTION ASSESSMENT OF COMPOSITES WITH EMBEDDED FIBRE OPTICS BY MEANS OF MICRO COMPUTED TOMOGRAPHY

G.CHIESURA (GHENT UNIVERSITY), G.LUYCKX, E.VOET, N.LAMMENS, W.VAN PAEPEGEM et al.

Several carbon fibre/epoxy laminate samples, having different diameters optical fibre sensor embedded, have been fatigue tested. The damage evolution has been followed up by means of Micro Computer Tomography. No significant evidence of cracks evolving around the sensors was found.