Note: Descriptions are shown in the official language in which they were submitted.
CA 02874973 2014-12-15
Description
FIELD OF THE INVENTION
The present invention relates to a novel fiber-metal laminate comprising
mutually 3D foam
impregnated fiber-reinforced composite layers and magnesium metal sheets. More
particularly, the
invention relates to a fiber-metal laminate comprising mutually bonded foam
impregnated 3D glass
fiber-reinforced composite layers and magnesium metal sheets having an optimal
configuration.
BACKGROUND OF THE INVENTION
Fiber-reinforced composites offer considerable weight advantage over other
materials, such as metals.
Generally, the weight savings are obtained at the sacrifice of other important
material properties such
as; ductility, toughness, bearing strength, conductivity and cold forming
capability. In order to
overcome these deficiencies, new hybrid materials called fiber-metal laminates
have been developed to
combine the best attributes of metal and composites.
Fiber-reinforced polymer (FRP) composites have been extensively utilized in
various industries over
recent years. The relatively high specific-strength and stiffness and
noteworthy fatigue and corrosion
endurance characteristics have made them useful materials for numerous
applications, particularly in
automotive fabrication. The weakest link in the FRPs has been their inter-
laminar shear capacity,
which makes them susceptible to impact loading. Thus, previous researchers
have tried to improve the
impact resistance of FRPs over the last over the last few decades. One of the
most effective means of
improving the impact resistance of FRPs has been to incorporate thin sheets to
form so-called fiber-
metal laminates (FMLs).
WO 2007/145512A1 discloses a FML comprising metal plates with an individual
thickness of 1mm.
Patent EP0312150 Al and EP0312151 describe other useful FMLs. US Patent
7446064 B2 employs a
glass fabric reinforcing layer and a polymer core but no 3D fabric and uses
aluminum alloy instead of
magnesium alloy. US patent 6824851 B1 employs a glass fabric that is not a 3D
fabric and the use a
honeycomb, not a 3D fabric. The present invention would be less costly to
obtain similar to greater
strength. US patent 8334055 B2 is a typical sandwich type composite with the
exception that there use
longitudinal fibers not through-thickness fibers dispersed within the epoxy
resin as in the much
stronger 3D fabric of the present invention.
Impact characterization of FMLs has been studied based on aluminum as the
constituent metal.
GLARE (Glass Laminate Aluminum Reinforced Epoxy, US Patent 5039571 A) FML, is
composed of
several very thin layers of metal (usually aluminum) interspersed with layers
of glass-fiber "pre-preg",
bonded together with a matrix such as epoxy. GLARES FMLs were developed with
emphasis upon the
effects of FML thickness and impactor mass on the impact response. It was
determined that specimen
thickness had a significant effect upon the failure modes of FMLs, such that
an increase in panel
thickness significantly enhanced the energy absorption capacity of the FMLs.
US Patent 4,500,589 describes the material under trade name ARALL, which is
fabricated by putting
fiber reinforcement in the adhesive bond lines between aluminum alloys. The
main difference between
ARALL and GLARE was that GLARE consists of glass fibers instead of the ARALL
aramid fibers
and that GLARE exhibits higher tensile and compressive, greater impact
behavior and greater residual
strength than ARALL. Currently, GLARE materials are commercialized in six
different standard
CA 02874973 2014-12-15
grades based upon unidirectional glass fibers embedded with epoxy adhesive
resulting in pre-pregs
with a normal fiber volume fraction of 60%. It has been found that ARALL
exhibits poor compressive
strength, which represents a major limitation. CARAL materials have exhibited
an improvement over
ARALL materials, such that they contain different amounts of carbon/epoxy pre-
pregs instead of
amarmid/epoxy pre-pregs.
Compared with aramid/epoxy, the carbon/epoxy composites possess higher
specific modulus, but
relatively low values of specific impact strength and strain to failure. In
terms of fatigue, it was
recognized that aramid fiber composites exhibit better low cycle fatigue
performance but worse high
cycle fatigue performance than carbon fiber composites. Moreover, the high
stiffness of carbon fibers
allows for extremely efficient crack bridging and therefore very low crack
growth rates.
Fiber-metal laminates or FMLs, such as described in US 4,500,589. For
instance, are obtained by
stacking alternating sheets of metal (most prefer aluminum) and the fiber-
reinforced pre-pregs and
curing the stack under heat and pressure, for example, in ships, cars, trains
aircraft and spacecraft.
They can also be used as sheets and/or a reinforcing element and/or and or as
a stiffener for (body)
structures of these transports, like for aircraft for wings, fuselage and tail
panels and/or skin panels and
structural elements of aircraft.
3D fiberglass (3DEG) fabric (ex. PATENT US 6338367 B1) is a newly developed
fiberglass
woven/braided fabric consisting of two bi-directional woven fabrics knitted
together by vertical
braided glass pillars. Besides glass fibers, carbon and even basalt fibers as
well as hybridizations of
these fibers could be used to form 3D clothes. The unique configuration of
fibers in 3D clothes have
been claimed to provide excellent impact resistance. However, there is little
evidence to support any
claims to date.
Polyurethane liquid foam is comprised of a two-part liquid that yields a high
strength, rigid, closed-cell
foam for cavity filling and buoyancy applications. The liquid is extremely
simple to use. Immediately
after mixing the two component parts, it is poured into cavities, then left to
quickly cure. The foam
imparts considerable stiffness with only minimal increase in weight. Optimal
results require use of
appropriate mixing procedures. The majority of foam use is used behind other
materials for domestic
and commercial uses, such as constructing furniture and preparing thermal
insulation panels for the
building industry.
US Patent 5547735 describes a metal-polymer laminate that has a bidirectional
reinforcing layer
containing roughly 45-70 volume per cent high strength glass fibers. The
bidirectional reinforcing
layer includes a center layer containing glass fibers oriented generally
parallel to a first direction and
first and second outer layers each reinforced with glass fibers oriented in a
second direction extending
generally transverse to the first direction. The bidirectional laminate is
suitable for use in aircraft
flooring and other applications requiring improved impact strength. This
approach lacks the additional
strength and stiffness character gained by employing a 3D glass fiber fabric
with reinforcing layers.
The use of magnesium alloys in various engineering applications has been
increasing steadily in recent
years, especially in the automotive industry. One of the primary reasons is
due to the low density of
magnesium (roughly 25% that of steel and 35% lower than aluminum, which makes
the weight of
magnesium alloy structural components very comparable to that of FRPs.
Magnesium alloy-based
fiber metal laminates several advantages over other metal base complexes such
as; a high strength to
weight ratio, improved electromagnetic shielding capability, relatively
density and lower cost
compared to aluminum and superior corrosion resistance. Previous studies have
found that compared
CA 02874973 2014-12-15
to 2024-T3-based GLARES, the impact resistance of magnesium-based FMLs was
lower than that of
GLARE5 when damage in the form of cracking of magnesium plates was taken as
the failure criterion.
However, when comparing the perforation limit, the specific impact energy of
the magnesium-based
FMLs was observed to be approximately equal to GLARES.
In addition, it has been found that magnesium-based alloys exhibit higher
specific tensile strength than
aluminum-based FMLs. Also the specific tensile strengths of magnesium-based
FMLs has been found
to be higher than that of 2024-TO aluminum alloy-based FMLs. It has also been
suggested that the
relatively lower elastic modulus and fracture properties exhibited by
magnesium-based FMLs may be
mitigated by selection of an appropriate volume of the composite constituents.
One of the most
common modes of damage for conventional FML configurations subjected to low
velocity impact is
the delamination that could develop within their FRP layers and/or within
FRP/metallic interfaces.
Current testing has shown that due to the resilient structure of the 3D
fabric, no delamination has
occurred. It has been determined that impact energy is absorbed mainly by
crushing vertical fibers and
the supporting foam beneath the region of impact, which leads to magnesium
oxide which has found
some current uses in the marketplace that include Ecomag magnesium boards and
in boards and panels
used employed by MoonrakerSIPS building systems, whereas the uses for
magnesium alloy as a
strengthening and reinforcing agent are very limited. US patent 7087317
describes a Glare type
composite laminated sandwich panel comprised of aluminum with adhesive where
at least one of the
aluminum sheets is preferably made of an aluminum non-heat treatable alloy
type Al-Mg with a
magnesium content of between 4 and 6%.
OBJECTIVES OF THE INVENTION
It is an object of the invention to provide a fiber metal laminate composite
comprised of mutually
bonded 3D glass fiber fabric layers and metal alloy sheets as layers
exhibiting optimal impact and
strength characteristics. It is a further object of the invention to provide a
laminate comprised of 3D E-
glass foam-injected fiber fabric core, layers of magnesium metal alloy sheets
and optional fiberglass
cloth layers all bonded by an appropriate epoxy resin/adhesive. Another
objective of the invention is to
show that the unique configuration of 3D E-glass fiber, foam, adhesive and
magnesium alloy sheets
will enable assembly of superior low velocity impact resistant panels. Another
object of the invention
is to show that the performance of the FMLs comprised of 3D fiber fabric,
foam, adhesive, magnesium
alloy sheets and optional fiberglass cloth will minimize delamination that
could occur within laminate
layers and/or within fiber fabric or fiberglass cloth/metallic interfaces.
Another object of the invention
is to advise of uses of such laminate panel as a structural element,
particularly in automobile and
marine vessel construction and repair.
Additional objects, features and advantages of the invention will be set forth
in the description, which
follows and in part will be obvious from the description or may be learned by
practice of the invention.
The objects, features and advantages of the invention may be realized and
obtained by means of the
instrumentalities and combination particularly pointed out in the appended
claims.
SUMMARY OF THE INVENTION
CA 02874973 2014-12-15
In one aspect, a structural laminate is provided having a layered composition
of first and second metal
alloy sheets as opposing outer layers.
In another aspect, liquid resin is applied to a 3D glass fiber fabric, which
creates expansion of the
through-thickness fibers of the fabric, which in turn creates spacing and
voids in the body of the 3D
glass fiber fabric core. The spacing is then filled with a polymeric foam.
In another aspect, the foam injected 3D glass fiber fabric layer is fitted
between the opposing metal
alloy sheets and bonded to the sheets using an adhesive material.
In another optional aspect, a thin layer of fiberglass cloth is fitted between
the 3D glass fiber fabric
layer and metal alloy sheet layers on one or opposing sides and bonded to the
3D fiber fabric layer and
sheet layers using an adhesive material.
In yet another aspect of the invention, a method of forming a structural 3D
fiber fabric metal laminate
panel from 3D fiber fabric metal alloy laminate components is provided.
The Steps involved in integration of the present invention comprise;
1) Step one involves sanding the surfaces of metal alloy sheets, blowing
surfaces clean and wiping
with acetone.
2) Step two involves applying a liquid polymeric resin onto 3D fiber fabric
and its core fibers and
permit to cure with addition of a hardener.
3) Step three involves injecting a liquid polymer foam (or alike) into the 3D
fiber core and permitting it
to solidify.
4) Step four involves the option of bonding a layer of fiberglass cloth to the
top and bottom or either of
the foam injected 3D glass fiber fabric core layer.
5) Step five involves applying adhesive/resin to the inside faces of the outer
metal alloy sheets to the
mating sides of the 3D core for bonding the constituents together.
6) Step six involves bonding two 3D glass fiber fabric metal alloy laminate
components together using
and an adhesive material to form a 3D glass fiber fabric metal alloy laminate
panel.
Needless to mention, in all the above described steps of 3D fiber fabric metal
laminate and 3D fiber
fabric metal laminate panel assembly, other completing operations of the
process will be carried-out at
the appropriate moments of the fabrication to produce a satisfactory laminate
component and laminate
panel of the required specifications. It will be apparent to those skilled in
the art that it is possible to
alter or modify the various details and steps of this invention without
departing from the spirit of the
invention. Therefore, the foregoing description is for the purpose of
illustrating the basic idea of this
invention and it does not limit the claims which are listed in this patent.
BRIEF DESCRIPTION OF THE FIGURES
The invention is described in reference to the following illustrations.
Figure us a top view in perspective of a magnesium alloy sheet layer according
to an embodiment of
the present invention.
CA 02874973 2014-12-15
Figure 2 is a top view of 3D glass fiber fabric material with applied resin
according to an embodiment
of the present invention.
Figure 3 is a front view of a 3D glass fiber fabric material with applied
resin according to an
embodiment of the present invention.
Figure 4 is a front view of 3D glass fiber fabric material with applied resin
and injected foam forming
a layer within the 3D glass fiber fabric material according to an embodiment
of the present invention.
Figure 5 is a front view of 3D glass fiber fabric material with applied resin,
injected foam forming a
layer within the 3D glass fiber fabric, optional fiberglass cloth layer and
outer magnesium alloy sheet
layers that bonded together by epoxy resin form a 3D E-glass fiber fabric
laminate component
according to an embodiment of the present invention.
Figure 6 is a front view of two 3D E-glass fiber fabric laminate components
bonded together to form a
3D E-glass fiber fabric laminate panel.
Figure 7 is a depiction in graphical form of the residual deformation of a 3D
E-glass fiber fabric
laminate test specimen being compared to woven fabric test specimens having
several different layers
(e.g. 4, 7 and 16 layers, respectively).
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE
INVENTION
In the following description, reference is made to the accompanying drawings,
which form a part
hereof, and which show, by way of illustration, specific embodiments in which
the invention may be
practiced. The present invention, however, may be practiced without the
specific details or with certain
alternative equivalent methods to those described herein. The method of
producing an innovative 3D
fiber fabric metal laminate component and 3D fiber fabric laminate panel
therefrom, using a 3D glass
fiber fabric injected with foam between thin sheets of magnesium alloy, with
or without a fiberglass
cloth layer reinforcing layer, will now be described in reference to the above
stated drawings. The
working principle of the laminate component will be described first and then
the particular way of
constructing the laminate component and associated laminate panel through a
combination of the
laminate components will be described.
In the description of the present invention and elsewhere the 3D E-glass fiber
fabric magnesium alloy
sheet laminate may occasionally be called a laminate or laminate component or
FML (fiber metal
laminate) or 3D glass fiber fabric metal laminate or 3D-E glass fiber metal
laminate or 3D glass fiber
fabric metal alloy laminate or 3D glass fiber fabric laminate or 3D laminate
or glass fiber fabric metal
laminate or glass fiber metal laminate or similar for the sake of brevity,
while still maintaining the
accuracy and intent of the description and the spirit of the present
invention. The 3D E-glass fiber
fabric magnesium alloy sheet panel may in the same vein within the context of
the description of the
present invention be called a 3D E-glass fiber metal alloy panel or 3D glass
fiber metal alloy panel or a
3D glass fiber metal panel or 3D laminate panel or similar for the sake of
brevity, while still
maintaining the accuracy and intent of the description and the spirit of the
present invention. In
addition, for the sake of brevity, the 3D E-glass fiber fabric material may be
called 3D glass fiber
fabric or 3D fiber fabric or 3D fabric or similar, while still maintaining the
accuracy and intent of the
description and the spirit of the present invention.
CA 02874973 2014-12-15
The basis of the present invention is a unique arrangement of 3D E-glass fiber
fabric-reinforced
composite layers, magnesium metal sheets, fiberglass cloth, foam and adhesive.
In accordance with the
invention, a 3D E-glass fiber fabric metal alloy laminate is provided
comprising fiber-reinforced
composite layers and magnesium metal sheets, the fiber properties relate to
the metal sheet properties
in a specific manner. It has been previously stated in this submission that
the preferred 3D glass fiber
for the invention is 3D E-glass fiber although other types of 3D glass fiber
could be employed to
achieve potentially similar results. It is stated and has also been previously
stated in this submission
that other types of fiber material could be employed in this invention.
The present invention comprises the assembly of a new 3D E-glass fiber fabric
metal laminate as a
component or article and a new 3D E-glass fiber fabric metal laminate panel by
bonding together two
or more of the new 3D E-glass fiber metal laminate components. More
specifically, the new 3D
laminate is comprised of a 3D E-glass fiber fabric (core) layer, an optional
fiberglass layer or layers
bonded to one or either side of the core layer and outer layers comprised of
magnesium sheets bonded
to the core or optional fiberglass layers. The core layer is comprised of 3D E-
glass fiber fabric material
with epoxy resin (adhesive) applied to the surface and used to impregnate
interior fibers of the core
plus a foam injected into the core material, which forms a layer within the
core material. The core
material itself constitutes a layer of the invention. An optional fiberglass
cloth layer is bonded to the
core layer using adhesive for further reinforcement.
In the present invention, fiber-reinforced composite layers preferably
comprise fibers treated with a
bonding system, preferably a metal adhesive. The system of adhesive, composite
layers and metal
sheets preferably provides its own internal heat development along with
pressure supplied by a vacuum
pressure system for curing the adhesive and forming a solid laminate component
and laminate panel.
The preferred epoxy resin (adhesive) as applied to the 3D glass fiber fabric,
is also used to adhere the
various layers of metals, fiberglass cloth and 3D fiber fabric material
structures together. The preferred
range in thickness for a 3D glass fiber fabric material is from 2 mm to 10 mm,
thus the 3D glass fiber
fabric laminate component can display various thicknesses dependent upon the
number of 3D glass
fiber fabric materials and their individual thicknesses employed to assembly
one new 3D laminate or
3D laminate panel.
In the present invention, the laminate outer magnesium alloy sheet layers can
be formed of one or more
magnesium alloy sheets of varying thicknesses dependent upon the desired
structural character or the
application of the new 3D laminate component or new 3D laminate panel. The
preferred range for
thickness of a single magnesium alloy sheet is 0.4 mm to 50 mm. The total
thickness of a magnesium
alloy sheet layer is contingent upon the number of sheets chosen to be
employed for a particular design
or application. In addition, the number of optional fiberglass cloth layers
employed in the new 3D
laminate component or 3D laminate panel can also vary from one to more layers
dependent upon the
desired structural character or the application of the new 3D laminate or new
3D laminate panel. The
preferred range for thickness of a singular optional fiberglass cloth is 0.2
mm to 0.4 mm. The total
thickness of a fiberglass cloth layer is contingent upon the number of units
of fiberglass cloth that are
chosen to be employed in a particular design or application.
In the present invention, preferably, when applying adhesive to join two
separate surfaces/layers of the
3D laminate component and 3D laminate panel, an appropriate amount of adhesive
is applied to both
surfaces to be joined simultaneously. It has been discovered by the inventors
that 3D glass fiber fabric
metal laminates with described fiber fabric properties have better structural
properties respecting joint
strength as well as in fatigue, in particular a higher resistance against low
velocity impact and fabric
CA 02874973 2014-12-15
delamination than conventional fiber-metal laminates of which the relevant
properties are not in
accordance with the methods of assembling the present invention.
In accordance with the invention and Figure 1, AZ31B magnesium alloy sheets
(1) ranging in
thickness from 0.4 to 50 mm are employed to form the outer layers of the new
3D glass fiber fabric
laminate component and 3D glass fiber fabric laminate panel. The magnesium
alloy sheets (1) as
shown in Figures 1, 4, 5 and 6 are sandblasted and treated with acetone to
ensure clean surfaces for
application of a bonding agent. Magnesium alloy is useful for its high
strength to weight ratio, low
density and corrosion resistance, all features useful in a laminate and
structural panel.
In accordance with the invention and Figure 2, 3D E-glass fiber fabric (2)
material consists of two bi-
directional woven fabrics connected in a uniform specific distance by vertical
column-like fibers. The
3D E-glass fiber fabric (2) preferably ranges in thickness from 2 to 10 mm and
was acquired from
China Beihai Fiberglass Co. Ltd. An innovative step in assembly of the present
innovation includes the
application of epoxy resin (3) to the surfaces of the 3D glass fiber fabric
(2) and resin (3) impregnation
of the interior fibers of the 3D glass fiber fabric (2), which encourages the
fibers connecting the top
and bottom cloth of the fabric (2) to expand through the thickness direction,
thus creating spacing and
voids in the fabric (2). In addition, Araldite Y564 (Bisphenole-A) epoxy resin
(3) plus Aradus 2954
(cycloaliphatic polyamine) hardener from Huntsman Co. were employed.
Considering the present
invention, the aforementioned resin and hardener together comprise the
aforementioned epoxy resin or
resin.
In accordance with the invention and Figure 3, 3D E-glass fiber fabric (2)
material is shown with
impregnating resin (3) that creates voids and spacing within the 3D E-glass
fiber fabric (2) material.
The resin (3) is applied to the surfaces and interior fibers of the 3D E-glass
fiber fabric, which creates
the spacing and voids in the 3D fabric.
In accordance with the invention and Figure 4, foam (4) material is injected
into the 3D E-glass fiber
fabric (2) material to fill the spacing and voids and to reinforce the
strength and provide stiffness to the
3D E-glass fiber fabric (2) material. To create the present invention, 81b
density pour type urethane
foam (4) from US Composites was preferably used. The 3D E-glass fiber fabric
(2) material along with
resin (3) and injected foam (4) form the core layer of the present invention.
In addition, magnesium alloy sheets (1) are bonded with resin (adhesive)(3) to
the outer sides of the 3D
E-glass fiber fabric (2) material to form the exterior covering for the new
laminate component and to
provide additional strength and stiffness to the laminate component. The
aforementioned epoxy resin
(adhesive) (3) used as a bonding agent and impregnating agent are the same
material in the present
invention, although varying bonding agents could be employed, although perhaps
not with the same
optimal results. The resin is used with a hardening agent to perform the
curing process, thus the
hardening agent is considered part of the epoxy resin or adhesive for the
purposes of the present
invention. The adhesive (3) dries in a matter of minutes, thus it is applied
and the layers bonded
together while the new laminate is under vacuum pressurization, to ensure a
strong bond. It was found
from lab testing, respecting the present invention that the optimal thickness
range of 3D glass fiber
fabric material (2) with resin (3) and foam (4), which form the core layer of
the laminate or laminate
component, is from 2 to 10 mm, with a preferred thickness of 4 mm to gain
greater cost and impact
integrity advantages.
In accordance with the invention and Figure 5 an optional step in the assembly
of a 3D E-glass fiber
fabric laminate component is the insertion of a thin layer of fiberglass cloth
(5) as a reinforcing layer
CA 02874973 2014-12-15
between the interior 3D E-glass fiber fabric core (2) layer and the outer
magnesium alloy sheet (1)
layer to increase strength and stiffness in the laminate. The fiberglass cloth
layer (5) is bonded to the
core fabric (2) layer using adhesive (3) material. The fiberglass reinforcing
(5) layer may be employed
on one or both sides of the 3D E-glass fiber fabric (2) and one or more
magnesium alloy sheets (1) may
be used on one or both sides of the 3D E-glass fiber fabric (2) layer. A new
3D E-glass fiber fabric (2)
magnesium alloy sheet (1) laminate is assembled by bonding together using
adhesive (3) all layers
noted in Figure 5.
In accordance with the present invention and Figure 6, two 3D E-glass fiber
fabric (2) magnesium
alloy sheet (1) laminates (laminate components) are bonded together with
adhesive (3) to form a new
3D fiber fabric (2) magnesium alloy sheet (1) laminate panel. For the purposes
of the present invention
the new laminate panel may be formed by bonding together two or more of the
laminate compone nts
with adhesive (2) material. All laminate layers are bonded together under
vacuum pressurization or
similar pressure application using adhesive (2) to ensure optimal bond
strength and optimal structural
characteristics of the present invention. Testing by the inventors has
revealed that the new 3D E-glass
fiber metal laminate panel exhibits superior structural properties to the new
3D E-glass fiber metal
laminate component alone.
In accordance with the present invention and Figure 7, there is displayed
herein a graph depicting the
residual deformation of the new 3D E-glass fiber fabric metal laminate
compared to conventional
woven fabric laminates. The energy levels used for testing specimens were
directed to generate
damage: (i) on the impact surface (ii) to the reverse side and (iii) in the
form of full perforation through
test specimens. The three types of damage generated are depicted as mode 1,
mode 2 and mode 3,
respectively. In the present invention, testing has shown that due to the
resilient structure of 3D glass
fiber fabric, no delamination has occurred. In addition, it has been
determined through testing that
impact energy is absorbed mainly by the crushing of vertical fibers and the
supporting foam beneath
the region of impact, which leads to higher impact resistance exhibited by the
3D glass fiber fabric
metal alloy laminate and a smaller damage area.
Low velocity impact response and failure modes for the present invention are
investigated
experimentally and computationally. The performance of the new 3D glass fiber
fabric metal laminates
(FMLs) are compared to that of conventional FMLs (fiber metal laminates) made
with various
numbers of layers of biaxial woven fabrics. The failure modes of the 3D
laminate test specimens are
characterized by being based upon the quantitative measurements of shape, type
and extent of damage
inflected upon the FMLs structure.
The impact characteristics of new assembled 3D FMLs are examined by
characterizing and comparing;
their energy absorption capacities, residual deformation and maximum
deformation due to low velocity
impact. Test results reveal that; the FMLs based upon the 3D glass fiber
fabric exhibit outstanding
impact absorption capacity, although the impact energy resistance is lower
than FMLs based upon
woven fabrics. In addition, a finite element analysis (FEA) framework
constructed using the
commercial finite element code ABAQUS so as to simulate the response of such
complex structures.
Results from running the FEA demonstrate that the simulation framework can be
used to optimize the
configuration of 3D FMLs for different loading situations and provide a useful
quality control check
during 3D FML assembly. Results of laboratory testing relevant to the present
invention are
summarized in the following Tables.
CA 02874973 2014-12-15
Table 1 displays a comparison of the flexural stiffness of FMLs made by
existing industry woven
fabric, compared to values for those made by the new 3D fiber fabric FMLs
particular to the invention.
The comparison shows that the new 3D FMLs exhibit a notably better performance
on weight and
material cost basis. The details of the FMLs noted in Table 1 are reported in
Table 2.
Table 1. Flexural stiffness of the FMLs
Flexural Stiffness Specific Flexural
Specimen ID
(N-m2) Stiffness (N-m2/g.mm-3)
3DF-FML 269.28 5729.53
4-layer FML 178.23 1916.40
7-layer FML 356.96 2189.96
16-layer FML 1287.25 3460.34
Table 2. Specifics of the different FMLs
Overall
Overall Reinforcemen Number of layers
Specimen IDDensity
Thickness (mm)(gimm3) t Fabric type of fabrics
3DF-FML 14.40 0.047 3DFGF 1
4-layer FML 4.87 0.093 biaxial woven 4
7-layer FML 6.53 0.163 biaxial woven 7
16=layer FML 10.16 0.372 biaxial woven 16
The present invention also incorporates new research data that shows the 3D E-
glass fiber fabric metal
alloy laminate exhibits a bending stiffness greater than conventional FMLs.
Employing four layers
resulted in flexural stiffness of the 3D glass fiber fabric FML that was found
to be greater than the
previously mentioned biaxial woven layers of FRPs. It was also determined that
the 3D glass fiber
fabric metal laminate could absorb the highest impact energy in comparison to
the aforementioned
woven layers of FRPs.
Many modifications may be made in the structures and processes to alter or
modify the various details
of this invention without departing from the spirit and scope thereof, which
are defined only in the
appended claims. For Example, one skilled in the art may discover that a
certain combination of
components, i.e. a particular core, etc., may give a sandwich panel with
certain advantages. Further,
certain dimensions or designs other than those disclosed here could be
produced for a particular
installation, but laminate components and laminate panels of these designs or
dimensions would
nevertheless fall within the scope of the claims herein, may prove
advantageous.
Needless to mention, in all the above described methods of 3D laminate and 3D
laminate panel
production, the other complementing operations of the assembly process will be
carried out at the
CA 02874973 2014-12-15
appropriate moments of the assembly to produce a satisfactory laminate of the
required specification. It
will be apparent to those skilled in the art that it is possible to alter or
modify the various details of this
invention without departing from the spirit of the invention. Therefore, the
foregoing description is for
the purpose of illustrating the basic idea of this invention and it does not
limit the claims which are
listed herein.
We believe that using the combination of: a 3D glass fiber fabric core
material; resin to create spacing
and voids in the laminate core that can be filled by injecting liquid foam to
cure and notable increase
structural strength and stiffness; employing an optional fiberglass cloth
layer as reinforcement
dependent upon product demand requirements of the laminate and laminate panel;
and using thin
magnesium metal alloy sheets as the outer layers of the new laminate and
derived new panel to
increase low velocity impact resistance and minimize delamination of layering
is new and truly
innovative.
What is believed to be the best mode of the invention has been described
above. However, it will be
apparent to those skilled in the art that these and other changes could be
made to the present invention
without departing from the spirit of the invention. The scope of the present
invention is indicated by
the broad general meaning of the terms in which the claims are expressed.
The research employed herein was funded by the National Science and
Engineering Research Council
of Canada (NSERC) and AUT021, a Network Center of Excellence in automotive
grant.
References:
Low-velocity Impact Response of Fiberglass/Magnesium FMLs with a New 3D
Fiberglass Fabric,
Zohreh Asaee, Shahin Shadlou and Farid Taheri, In Press.
I
