Download Abstract summaries - ICCM International Committee on

F. DEFORMATION AND FRACTURE OF COMPOSITES
Interaction of Matrix Cracking and Delamination in Cross-Ply Laminates:
Simulations with Stochastic Cohesive Zone Elements
VV Silberschmidt, ZR Khokhar, IA Ashcroft (Loughborough Univ)
This paper is aimed at the interaction between matrix cracking and delamination failure
mechanisms in CFRP cross-ply laminates under quasi-static tensile loading. This effect is
studied in numerical finite-element simulations by introducing stochastic cohesive zone
elements to account for and analyse the effect of the microstructural randomness exhibited by
these laminates. (F8:1)
Analysis of Transverse Ply Cracks using Computed Tomography
I Sinclair, AJ Moffat, P Wright, SM Spearing (Univ of Southampton)
X-ray computed tomography was used to image, in three-dimensions, carbon fibre-epoxy
[90/0]s laminate samples. Combining the technique with in situ loading it has been possible to
quantify the crack opening displacement (COD) in transverse ply cracks, enabling the
determination of the contributions of both mechanical and residual stresses to COD. (F8:2)
2D Elastodynamics of an Interface Crack
I Mykhailova, O Menshykov, I Guz (Univ of Aberdeen)
The study concerns with elastodynamic response of interface cracks with allowance for the
crack faces interaction. The problem is solved by the boundary integral equations method.
The distributions of displacements and tractions at the interface and the crack surface are
obtained and analysed. The stress intensity factors are also computed. (F8:3)
A ECM-Based Method for Predicting Failure of Composite Laminates
F Wang (Southwest Univ) X Zeng (Sichuan Univ) J Zhang (Shanghai Univ)
A new analytical approach based upon the equivalent constraint model was established to
constitute an available predictive approach for investigating progressive failure and analyzing
ultimate strength. The effects of lamina properties, lay-up configurations and loading
conditions on the behaviors of the laminates were examined in this paper. (F8:4)
Damage Development in Composites Initiated after Matrix Cracking
D Katerelos, J Varna (Luleå Univ of Technology)
Stress state in the vicinity of transverse cracks tip is investigated. An analytical model is used
for the stress components calculation. Knowing the stress concentration factors values at the
tip of the crack, the possibility of new damage modes initiation is examined. SCF is
recalculated taking into account the possible local stiffness reduction due to new modes of
damage. (F8:5)
Thursday
09.10
F. DEFORMATION AND FRACTURE OF COMPOSITES
The Role of Delamination in Notched and Unnotched Tensile Strength
MR Wisnom (Univ of Bristol)
Delamination is usually associated with through-thickness failure, but in fact can have a major
effect on in-plane strength of notched and unnotched laminates. This paper considers tensile
strength of quasi-isotropic laminates and results from scaled tests to show how delamination
is critical in damage development and ultimate failure. (F8:6)
Discrete Modeling of Arbitrary Matrix Cracking and Delaminations in
Laminated Composites
E Iarve, M Gurvich (Univ of Dayton RI)
Matrix cracking and delamination initiation, propagation, and interaction prediction in
laminated composites without any prior knowledge and/or meshing of matrix cracking
surfaces was accomplished by combining stress and fracture mechanics-based constitutive
modeling within a mesh independent crack-modeling framework. Tensile loading of a quasiisotropic laminate was performed and captured the correct delamination sequence, evolving
from randomly generated matrix cracks, as well as the failure load values. (F8:7)
Size Effects on Strength of Notched CFRP Laminates Loaded in Bending
L Asp, S Nilsson (Swerea Sicomp AB) A Bredberg (Saab Aerostructures)
Notched composite panels are loaded in bending or compression and it has been shown that
a larger hole results in a lower failure strain, although the W/D-ratio is the same. It has also
been demonstrated that the failure strain is much higher in bending compared to compression.
(F8:8)
An Aproach for Dealing with High Local Stresses in Finite Element
Analyses
F Helenon, MR Wisnom, SR Hallett (Univ of Bristol)
A method for quantifying the criticality of high localised stress concentrations in finite element
analysis of composite structures is proposed. It aims to predict the onset of delamination and
is inspired from fracture mechanics theory for orthotropic materials. Examples of application
show the approach to give conservative results. (F8:9)
Fracture Behavior and Residual Strength of CFRP Specimen after
Lightning Test
Y Hirano, Y Iwahori (JAXA) S Katsumata (Grad School of Tokyo Tech) A Todoroki (Tokyo
Institute of Tech)
This paper examines the fracture behaviour of CFRP due to lightning strikes; the artificial
lightning tests are performed with CFRP specimens. The results of visual inspection, NDTs
and subsequent compression test show the relationship between damage size and lightning
parameters, and residual strength characteristics after lightning damage. (F8:10)
Bending Response of Sandwich Panels with Graded Core: 3D Elasticity
Analysis
B Woodward, M Kashtalyan (Univ of Aberdeen)
The paper presents the results of an investigation of the behaviour of sandwich panels, with
stiffness of the core graded in the thickness direction, on the basis of the recently developed
3D elasticity solution. The use of graded core to improve performance of sandwich structures,
especially under localised loading, is examined and discussed. (F8:11)
11.30
Generalized Eshelby Solution for Gradient Model of Interphase Layer
and its Application to Predicting the Properties of Micro- and
Nanocomposites
S Lurie (RAS) I Guz (Univ of Aberdeen)
The generalized Eshelby problem is extended to the higher-order continuum theory, which
takes into account the specific properties of interphase layer. This solution has the properties
of the natural cylindrical ‘transverse isotropy’ and can be very effective for predicting the
properties of micro- and nanocomposites with whiskerized fibres. (F8:12)
Observations on Local Strain Fields in CFRP Stiffened Element Tests
using Digital Image Correlation
V Bloodworth, E Greenhalgh (Imperial College London) B Falzon (Monash Univ) P Curtis
(DSTL)
The local skin/stiffener strain state during failure in representative stiffened elements was
characterised using Digital Image Correlation (DIC), fractography and FEA. Parametric
studies were conducted on element tests which indicated crucial design parameters in
stiffened panels. A link between initiation in the element and full-scale stiffened panels was
also established. (F8:13)
Meshless Cohesive Segments Method for Crack Initiation and
Propagation in Composites
E Barbieri, M Meo (Univ of Bath)
A modelling method aimed at eliminating the need of explicit crack representation in bidimensional structures is presented for the simulation of the initiation and subsequent
propagation of multiple cracks within composite materials. This is achieved by combining a
meshless method with a physical stress-displacement based criterion known as Cohesive
Model. Results are showed for classical benchmark cases. (F8:14)
Investigation of Kink-Band Formation under Biaxial Stress State
R Gutkin, S Pinho, P Robinson, P Curtis (Imperial College London)
This paper investigates longitudinal compressive failure. Two failure modes were observed
experimentally for pure longitudinal compression: shear-driven fibre compressive failure and
kink-band formation. In a micromechanical numerical study, failure envelopes for combined
longitudinal compression and in-plane shear were predicted. (F8:15)