JEC COMPOSITES MAGAZINE - Issue #88 - April 2014 - Special JEC Americas Spring Edition - 50

OHT tests
[2] (Figure 4). These
advances in computational modelling mean
that it may be possible
to significantly reduce
the number of OHTs by
performing large numbers
of FE analyses instead
and validating the results
with limited and carefully
selected experiments.
Although the above
methods produce quite
accurate predictions and
very detailed ply-by-ply
maps of damage and
interface delaminations, a
disadvantage is that each
analysis typically takes
a few hours to perform,
and the model may take
Fig. 3: OHT strength prediction for composite laminates made of
one or two days to build,
Hexcel F593 carbon-epoxy
depending on the speed
OHT data [1, 2].
of the computer and the skill of the analyst.
Time is also required for the post-procesOHT scaling and laminate lay-ups
sing of FE results.
A problematic feature of OHT observed in
experiments is the size effect - i.e. strength
Master stiffness data
reduces with increasing specimen size,
for OHT specimens
while keeping the ratio between the hole
Recently, Professor Tsai [4] proposed
diameter and the specimen width constant.
a method to estimate the failure of fibre
By incorporating the various damage
reinforced composite laminates using the
mechanisms into the FE model, it is now
stiffness invariants and maximum principal
possible to reproduce the size effect quite
strain criterion. We decided to further invessuccessfully [2, 3] (Figure 3). The effect of
tigate this idea for OHT for two different
changing the laminate lay-up sequence may
material systems, i.e. Hexcel F593 and
also be predicted with reasonable accuracy
IM7-MTM. Professor Tsai suggested that
for most carbon-epoxy
thermoset systems, the
trace of the plane stress
stiffness matrix of any given unidirectional lamina
is constant irrespective
of their orientation, i.e.:
TQ=Qxx+Qyy+2Qxy=K.
It was shown that for any
given lamina direction, the
normalized stiffness, i.e.
stiffness component divided by the stiffness trace,
is similar for many carbonepoxy systems. Applying
Fig. 4: Stiffness of OHT carbon-epoxy laminates
the same idea to OHT
LU1 [-45/904/45/904/0]s
[-45/902/45/902/LU2 [-45/902/45/902/-45/902/45/0]s
LU3 [-45/902/45/0]2s
LU4 [45/0/-45/90]3s
LU5 [45/02/-45/90]2s
LU6 [45/02/-45/02/45/02/-45/90]s
LU7 [45/04/-45/04/90]

50 jec composites magazine / No88 April 2014

specimens, the results are shown in Fig. 4,
where each of the cases has been analyzed
with an FE model similar to the one shown
in Figure 1. The trace of the stiffness matrix
is indeed relatively constant for the openhole specimens, for both IM7-MTM45
and Hexcel F593. When normalized with
respect to the trace, the two sets of data may
be collapsed to a master set, although they
came from two different materials systems.
This can be quite useful and convenient for
a design engineer who wants to compare
the OHT stiffness of various materials and
lay-up sequences. By using the normalized
stiffness data (master stiffness data) and
stiffness data for one of the lay-up designs,
one can calculate the stiffness for any other
lay-up design.

Strain to failure and
strength of OHT specimens
Fig. 5 shows the stress-strain curves obtained from progressive damage simulation of
OHT laminates of various lay-ups. In the
figure, FMF refers to "first matrix failure"
(onset of failure in the matrix), FFF refers
to "first fibre failure" (first occurrence
of fibre break) and OHT strength is the
maximum stress reached by the specimen.
We can see that the variance in the failure
strains is smaller than the variance in the

Fig. 5: Stress-strain curve of OHT specimens



JEC COMPOSITES MAGAZINE - Issue #88 - April 2014 - Special JEC Americas Spring Edition

Table of Contents for the Digital Edition of JEC COMPOSITES MAGAZINE - Issue #88 - April 2014 - Special JEC Americas Spring Edition

Cover
Edito
Point of view: greener solutions
Contents
COMPANY & BUSINESS In Brief
Agenda of Events
APPLICATIONS
Biocomposites
Industry
MARKET
Carbon
U.S.
SPECIAL JEC AMERICAS - SPRING EDITION
Gain insight into the JEC 2014 l.C.S. Americas programme
JEC Innovation Awards Program 2014
C-Ply
Laminates Design
Testing
Properties
Optimization
OHT tests
Design
ATM
BVID
Application
RESEARCH & DEVELOPMENT
Modelling
Simulation
TECHNOLOGY & INNOVATIONS
Oil & gas
Dielectric analysis
Simulation
Index
In the world
JEC COMPOSITES MAGAZINE - Issue #88 - April 2014 - Special JEC Americas Spring Edition - Cover
JEC COMPOSITES MAGAZINE - Issue #88 - April 2014 - Special JEC Americas Spring Edition - 2
JEC COMPOSITES MAGAZINE - Issue #88 - April 2014 - Special JEC Americas Spring Edition - Edito
JEC COMPOSITES MAGAZINE - Issue #88 - April 2014 - Special JEC Americas Spring Edition - Point of view: greener solutions
JEC COMPOSITES MAGAZINE - Issue #88 - April 2014 - Special JEC Americas Spring Edition - 5
JEC COMPOSITES MAGAZINE - Issue #88 - April 2014 - Special JEC Americas Spring Edition - Contents
JEC COMPOSITES MAGAZINE - Issue #88 - April 2014 - Special JEC Americas Spring Edition - 7
JEC COMPOSITES MAGAZINE - Issue #88 - April 2014 - Special JEC Americas Spring Edition - 8
JEC COMPOSITES MAGAZINE - Issue #88 - April 2014 - Special JEC Americas Spring Edition - Ad9
JEC COMPOSITES MAGAZINE - Issue #88 - April 2014 - Special JEC Americas Spring Edition - Ad10
JEC COMPOSITES MAGAZINE - Issue #88 - April 2014 - Special JEC Americas Spring Edition - COMPANY & BUSINESS In Brief
JEC COMPOSITES MAGAZINE - Issue #88 - April 2014 - Special JEC Americas Spring Edition - Agenda of Events
JEC COMPOSITES MAGAZINE - Issue #88 - April 2014 - Special JEC Americas Spring Edition - 11
JEC COMPOSITES MAGAZINE - Issue #88 - April 2014 - Special JEC Americas Spring Edition - Biocomposites
JEC COMPOSITES MAGAZINE - Issue #88 - April 2014 - Special JEC Americas Spring Edition - 13
JEC COMPOSITES MAGAZINE - Issue #88 - April 2014 - Special JEC Americas Spring Edition - 14
JEC COMPOSITES MAGAZINE - Issue #88 - April 2014 - Special JEC Americas Spring Edition - Industry
JEC COMPOSITES MAGAZINE - Issue #88 - April 2014 - Special JEC Americas Spring Edition - 16
JEC COMPOSITES MAGAZINE - Issue #88 - April 2014 - Special JEC Americas Spring Edition - Carbon
JEC COMPOSITES MAGAZINE - Issue #88 - April 2014 - Special JEC Americas Spring Edition - 18
JEC COMPOSITES MAGAZINE - Issue #88 - April 2014 - Special JEC Americas Spring Edition - 19
JEC COMPOSITES MAGAZINE - Issue #88 - April 2014 - Special JEC Americas Spring Edition - U.S.
JEC COMPOSITES MAGAZINE - Issue #88 - April 2014 - Special JEC Americas Spring Edition - 21
JEC COMPOSITES MAGAZINE - Issue #88 - April 2014 - Special JEC Americas Spring Edition - 22
JEC COMPOSITES MAGAZINE - Issue #88 - April 2014 - Special JEC Americas Spring Edition - SPECIAL JEC AMERICAS - SPRING EDITION
JEC COMPOSITES MAGAZINE - Issue #88 - April 2014 - Special JEC Americas Spring Edition - Gain insight into the JEC 2014 l.C.S. Americas programme
JEC COMPOSITES MAGAZINE - Issue #88 - April 2014 - Special JEC Americas Spring Edition - 25
JEC COMPOSITES MAGAZINE - Issue #88 - April 2014 - Special JEC Americas Spring Edition - JEC Innovation Awards Program 2014
JEC COMPOSITES MAGAZINE - Issue #88 - April 2014 - Special JEC Americas Spring Edition - 27
JEC COMPOSITES MAGAZINE - Issue #88 - April 2014 - Special JEC Americas Spring Edition - 28
JEC COMPOSITES MAGAZINE - Issue #88 - April 2014 - Special JEC Americas Spring Edition - 29
JEC COMPOSITES MAGAZINE - Issue #88 - April 2014 - Special JEC Americas Spring Edition - 30
JEC COMPOSITES MAGAZINE - Issue #88 - April 2014 - Special JEC Americas Spring Edition - C-Ply
JEC COMPOSITES MAGAZINE - Issue #88 - April 2014 - Special JEC Americas Spring Edition - 32
JEC COMPOSITES MAGAZINE - Issue #88 - April 2014 - Special JEC Americas Spring Edition - 33
JEC COMPOSITES MAGAZINE - Issue #88 - April 2014 - Special JEC Americas Spring Edition - 34
JEC COMPOSITES MAGAZINE - Issue #88 - April 2014 - Special JEC Americas Spring Edition - 35
JEC COMPOSITES MAGAZINE - Issue #88 - April 2014 - Special JEC Americas Spring Edition - Ad35
JEC COMPOSITES MAGAZINE - Issue #88 - April 2014 - Special JEC Americas Spring Edition - Ad36
JEC COMPOSITES MAGAZINE - Issue #88 - April 2014 - Special JEC Americas Spring Edition - Laminates Design
JEC COMPOSITES MAGAZINE - Issue #88 - April 2014 - Special JEC Americas Spring Edition - 37
JEC COMPOSITES MAGAZINE - Issue #88 - April 2014 - Special JEC Americas Spring Edition - 38
JEC COMPOSITES MAGAZINE - Issue #88 - April 2014 - Special JEC Americas Spring Edition - Testing
JEC COMPOSITES MAGAZINE - Issue #88 - April 2014 - Special JEC Americas Spring Edition - 40
JEC COMPOSITES MAGAZINE - Issue #88 - April 2014 - Special JEC Americas Spring Edition - 41
JEC COMPOSITES MAGAZINE - Issue #88 - April 2014 - Special JEC Americas Spring Edition - Properties
JEC COMPOSITES MAGAZINE - Issue #88 - April 2014 - Special JEC Americas Spring Edition - 43
JEC COMPOSITES MAGAZINE - Issue #88 - April 2014 - Special JEC Americas Spring Edition - 44
JEC COMPOSITES MAGAZINE - Issue #88 - April 2014 - Special JEC Americas Spring Edition - 45
JEC COMPOSITES MAGAZINE - Issue #88 - April 2014 - Special JEC Americas Spring Edition - Optimization
JEC COMPOSITES MAGAZINE - Issue #88 - April 2014 - Special JEC Americas Spring Edition - 47
JEC COMPOSITES MAGAZINE - Issue #88 - April 2014 - Special JEC Americas Spring Edition - 48
JEC COMPOSITES MAGAZINE - Issue #88 - April 2014 - Special JEC Americas Spring Edition - OHT tests
JEC COMPOSITES MAGAZINE - Issue #88 - April 2014 - Special JEC Americas Spring Edition - 50
JEC COMPOSITES MAGAZINE - Issue #88 - April 2014 - Special JEC Americas Spring Edition - 51
JEC COMPOSITES MAGAZINE - Issue #88 - April 2014 - Special JEC Americas Spring Edition - Design
JEC COMPOSITES MAGAZINE - Issue #88 - April 2014 - Special JEC Americas Spring Edition - 53
JEC COMPOSITES MAGAZINE - Issue #88 - April 2014 - Special JEC Americas Spring Edition - 54
JEC COMPOSITES MAGAZINE - Issue #88 - April 2014 - Special JEC Americas Spring Edition - ATM
JEC COMPOSITES MAGAZINE - Issue #88 - April 2014 - Special JEC Americas Spring Edition - 56
JEC COMPOSITES MAGAZINE - Issue #88 - April 2014 - Special JEC Americas Spring Edition - BVID
JEC COMPOSITES MAGAZINE - Issue #88 - April 2014 - Special JEC Americas Spring Edition - 58
JEC COMPOSITES MAGAZINE - Issue #88 - April 2014 - Special JEC Americas Spring Edition - 59
JEC COMPOSITES MAGAZINE - Issue #88 - April 2014 - Special JEC Americas Spring Edition - 60
JEC COMPOSITES MAGAZINE - Issue #88 - April 2014 - Special JEC Americas Spring Edition - 61
JEC COMPOSITES MAGAZINE - Issue #88 - April 2014 - Special JEC Americas Spring Edition - Application
JEC COMPOSITES MAGAZINE - Issue #88 - April 2014 - Special JEC Americas Spring Edition - 63
JEC COMPOSITES MAGAZINE - Issue #88 - April 2014 - Special JEC Americas Spring Edition - Modelling
JEC COMPOSITES MAGAZINE - Issue #88 - April 2014 - Special JEC Americas Spring Edition - 65
JEC COMPOSITES MAGAZINE - Issue #88 - April 2014 - Special JEC Americas Spring Edition - Simulation
JEC COMPOSITES MAGAZINE - Issue #88 - April 2014 - Special JEC Americas Spring Edition - 67
JEC COMPOSITES MAGAZINE - Issue #88 - April 2014 - Special JEC Americas Spring Edition - 68
JEC COMPOSITES MAGAZINE - Issue #88 - April 2014 - Special JEC Americas Spring Edition - 69
JEC COMPOSITES MAGAZINE - Issue #88 - April 2014 - Special JEC Americas Spring Edition - 70
JEC COMPOSITES MAGAZINE - Issue #88 - April 2014 - Special JEC Americas Spring Edition - 71
JEC COMPOSITES MAGAZINE - Issue #88 - April 2014 - Special JEC Americas Spring Edition - 72
JEC COMPOSITES MAGAZINE - Issue #88 - April 2014 - Special JEC Americas Spring Edition - Oil & gas
JEC COMPOSITES MAGAZINE - Issue #88 - April 2014 - Special JEC Americas Spring Edition - 74
JEC COMPOSITES MAGAZINE - Issue #88 - April 2014 - Special JEC Americas Spring Edition - 75
JEC COMPOSITES MAGAZINE - Issue #88 - April 2014 - Special JEC Americas Spring Edition - Dielectric analysis
JEC COMPOSITES MAGAZINE - Issue #88 - April 2014 - Special JEC Americas Spring Edition - 77
JEC COMPOSITES MAGAZINE - Issue #88 - April 2014 - Special JEC Americas Spring Edition - 78
JEC COMPOSITES MAGAZINE - Issue #88 - April 2014 - Special JEC Americas Spring Edition - 79
JEC COMPOSITES MAGAZINE - Issue #88 - April 2014 - Special JEC Americas Spring Edition - Simulation
JEC COMPOSITES MAGAZINE - Issue #88 - April 2014 - Special JEC Americas Spring Edition - Index
JEC COMPOSITES MAGAZINE - Issue #88 - April 2014 - Special JEC Americas Spring Edition - In the world
JEC COMPOSITES MAGAZINE - Issue #88 - April 2014 - Special JEC Americas Spring Edition - 83
JEC COMPOSITES MAGAZINE - Issue #88 - April 2014 - Special JEC Americas Spring Edition - 84
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