26.1.1-R2 X-RAY MICROTOMOGRAPHIC IMAGING OF KINK BANDS IN CARBON FIBRE-EPOXY COMPOSITES

Y.WANG (UNIVERSITY OF MANCHESTER), C.SOUTIS, P.WITHERS

The three-dimensional morphology of damage modes in kink bands formed in unidirectional carbon fibre/epoxy composites under compression is presented by using X-ray micro-tomography. Three-dimensional segmented volume and two-dimensional orthogonal virtual sections are used to help explain the kink band geometry.

26.1.1-R4 DEVELOPMENT AND INTEGRATION OF INNOVATIVE GLASS FIBRE SENSORS INTO ADVANCED COMPOSITES FOR APPLICATIONS IN HOSTILE ENVIRONMENTS

B.MILSOM (POLITECNICO DI TORINO), M.OLIVERO, D.MILANESE, M.ROSEMAN, S.GIANNIS et al.

The diffusion of water into a vinyl ester was measured using optical fibre sensors. Evanescent field sensors were prepared and compared to Bragg fibre gratings. Both were capable of detecting the ingress of water into the resin through different mechanisms.

26.1.1-R5 HOMOGENIZATION ANALYSIS OF 3-D COMPOSITES USING FINITE THICKNESS UNIT-CELL MODEL

MR.NASUTION (TOKYO METROPOLITAN UNIVERSITY), N.WATANABE, A.KONDO, A.YUDHANTO

This paper discusses an improvement in homogenization analysis of periodic structure by modeling the finite-thickness unit-cell model and relieving periodic boundary condition at the top and bottom of unit-cell surfaces to consider the effect of finite-thickness in 3-D composites.

26.1.1-R6 FINITE FRACTURE MECHANICS VS. COHESIVE CRACK MODELLING: AN ANALYTICAL COMPARISON BASED ON EXAMPLE PROBLEMS

P.CORNETTI (POLITECNICO DI TORINO), A.SAPORA, A.CARPINTERI

In the present paper we want to corroborate the Finite Fracture Mechanics approach by showing that, for a couple of example problems, failure load predictions are very close to the ones provided by the widely-spread and well-established Cohesive Crack Model.

26.1.1-R7 HIGHLY EXTENSIBLE WAVY-PLY SANDWICH WITH COMPOSITE SKINS AND CRUSHABLE CORE

P.ROBINSON (IMPERIAL COLLEGE LONDON), S.PIMENTA

A new concept for wavy-skin sandwich structures with crushable core is proposed. Specimens designed by analytical and FE modelling, and manufactured using carbon-epoxy skins and PMI-foam core, exhibited large tensile-strains (8.6%) and energy-dissipation (9.4kJ/kg), while maintaining high tensile strength (1570MPa).

26.1.2-R2 GREENSTICK FRACTURES OR HOW PLANT BRANCHES, YOUNG MAMMAL BONES AND COMPOSITE PULTRUDED RODS BREAK

G.VARGAS (UNIVERSITY OF THE BASQUE COUNTRY), F.MUJIKA

Analytical and experimental work for studying anisotropic beams (e.g. branches, young bones, and unidirectional FRP) subjected to flexural loading is presented. Greenstick fracture mode has been experimentally studied on pultruded GFRP rods under 3-PB and 4-PB with several span-to-diameter ratios.

26.1.2-R4 EFFECT OF ENVIRONMENTAL CONDITIONING ON BURST PRESSURE OF CARBON/EPOXY FILAMENT WOUND COMPOSITE PIPES

H.JUNIOR (FEDERAL UNIVERSITY OF RIO GRANDE DO SUL), ML.TONATTO, H.FARIA, A.TORRES MARQUES, S.CAMPOS AMICO

Burst pressure of filament wound pipes with different winding angle was studied. The effect of hygrothermal conditioning were analytically and numerically evaluated. Burst pressure increased up to ±55°, for failure criteria studied. The environmental conditioning reduced burst pressure in 2-3%.

26.1.2-R5 MULTI-SCALE MODELLING AND CHARACTERIZATION OF 3D WOVEN COMPOSITES USING UNIT CELLS

Q.PAN (UNIVERSITY OF NOTTINGHAM), S.LI

Introduces a methodology to predic effective properties of fabric composite. This methodology was been integrated into a commercialised software, UnitCells©, which is an automated multi-scale composite analysis toolbox for characterisation of a wide range of composites, including 3D woven composites.

26.1.2-R6 COMPARISON OF THE SIZE EFFECT PREDICTED BY A COHESIVE ZONE MODEL AND THE FINITE FRACTURE MECHANICS FOR THE FIBER-MATRIX DEBONDING

IG.GARCÍA (UNIVERSIDAD DE SEVILLA), M.PAGGI, V.MANTIČ

The predictions of a cohesive zone model and a finite fracture mechanics approach for the fiber-size effect on the transverse tension causing the debond initiation are compared. A good agreement, except for the very small fibres, is observed.

26.1.2-R7 DELAMINATION BEHAVIOR OF ASYMMETRIC SANDWICH SHELLS UNDER AXIAL COMPRESSIVE LOADING

M.PIETREK (TECHNISCHE UNIVERSITÄT BRAUNSCHWEIG), P.HORST, M.MUND, K.DILGER

The work covers the experimental and numerical analysis of asymmetric sandwich shells consisting of a CFRP-skin, an aluminum skin and a PMI foam core under axial compressive load. The manufacturing process, testing and the comparison with FE-simulations are presented.

26.1.3-R2 DAMAGE MODELING OF LAMINATED COMPOSITES: VALIDATION OF THE INTRA_LAMINAR LAW OF SAMCEF AT THE COUPON LEVEL FOR UD PLIES

M.BRUYNEEL, JP.DELSEMME (LMS SAMTECH), AC.GOUPIL, P.JETTEUR, C.LEQUESNE et al.

Progressive intra-laminar damage modeling of laminated composites is adressed. The material model for UD plies available in SAMCEF is presented, as well as the associated identification procedure. The model is validated at the coupon level.

26.1.3-R4 IMPROVED VEHICLE PERFORMANCE THROUGH LOCAL REINFORCEMENTS

I.VAN DE WEYENBERG (FLANDERS' DRIVE), P.CAMPESTRINI

This paper presents an extensive evaluation of different reinforcing technologies and their effect on the mechanical properties of a structure. With the additional cost estimation feature and the environmental impact study, a complete cost-benefit analysis is provided.

26.1.3-R5 MODELLING OF TIME AND RATE DEPENDENT BEHAVIOUR OF 3D BRAID COMPOSITES USING CONTINUUM-BASED MULTI-SCALE ANALYSIS

H.AHN (SEOUL NATIONAL UNIVERSITY), WR.YU

A new numerical method is developed that can reflect the microstructural change of the textile structure during time dependent loading and can calculate the stress increments due to the deformation.

26.1.3-R6 MEASUREMENT OF THE INTRALAMINAR FRACTURE TOUGHNESS AND R-CURVE OF POLYMER COMPOSITES LAMINATES USING THE SIZE EFFECT LAW

G.CATALANOTTI (FEUP), P.CAMANHO

This paper presents a new methodology to measure the crack resistance curve of polymer composites reinforced by unidirectional fibres. Rather than using standard test methods the identification of the size-effect law is used to measure the crack resistance curve.

26.1.3-R7 DYNAMIC RESPONSE OF SYNTACTIC FOAM CORE SANDWICH USING A MULTIPLE SCALES BASED ASYMPTOTIC METHOD

KVN.GOPAL (IIT MADRAS), J.ASDEV

A multiple-scales asymptotic method is formulated to model the free vibration response of sandwich composite plates with syntactic foam core. A parametric study of the influence of plate thickness and inclusion geometry on the dynamic response is presented.

26.1.4-R2 MEASURE OF FRACTURE TOUGHNESS IN COMPOSITE STRUCTURES USING INFRARED THERMOGRAPHY

T.LISLE, N.HONGKARNJANAKUL, C.BOUVET (ICA / ISAE), ML.PASTOR, P.MARGUERES et al.

Evaluating the fracture toughness of compressive fiber failure is very complex. The infrared thermography has been used to follow compressive failure mode developing during an indentation test and a compression after impact test, and to evaluate the fracture toughness.

26.1.4-R4 ENGINEERING PROPERTIES OF CARBON/EPOXY FILAMENT WOUND UNIDIRECTIONAL LAMINATES

JH.ALMEIDA JÚNIOR, C.STAUDIGEL, G.CAETANO, S.AMICO (FEDERAL UNIVERSITY OF RIO GRANDE DO SUL)

The aim of this study is to evaluate the properties of unidirectional carbon/epoxy laminates manufactured by dry filament winding. Most of the independent elastic constants, major and minor Poisson’s ratio and strength properties were obtained, except those related to shear.

26.1.4-R5 ANALYTICAL AND NUMERICAL METHODS TO ACCESS THE MECHANICAL ELASTIC PROPERTIES OF A DEFORMED WOVEN REINFORCED COMPOSITE MATERIAL.

A.LEBRUN (SCHOOL OF MINES PARISTECH), S.JOANNÈS, J.RENARD

Due to the forming process, the fabric of a woven composite is deformed thus modifie the mechanical properties. The present contribution deals with the characterization of such deformed structures with a new analytical and numerical approach.

26.1.4-R6 COMPARISON BETWEEN COHESIVE ZONE MODELS AND A COUPLED CRITERION FOR PREDICTION OF EDGE DEBONDING

T.VANDELLOS (ONERA), E.MARTIN, D.LEGUILLON

Several shapes of cohesive zone models (bilinear, trilinear and trapezoidal) are compared with the coupled strength and energy criterion in order to assess their capabilities to predict the failure onset of a bonded specimen submitted to bending.

26.1.4-R7 COMBINED SHEAR-COMPRESSION TEST TO CHARACTERIZE FOAMS UNDER OBLIQUE LOADING FOR BICYCLE HELMETS

Y.MOSLEH (KULEUVEN), KV.BOSCHE, JV.SLOTEN, I.VERPOEST, J.IVENS

In bicycle traffic accidents, impacts are oriented at oblique angles resulting in harmful rotational accelerations to the head. A new test method to measure combined shear-compression loading on foams was developed and the results were compared with rotational impact tests.