University of Plymouth
PEARL https://pearl.plymouth.ac.uk
Faculty of Science and Engineering School of Engineering, Computing and Mathematics
2019-09
Flexural performance and cost efficiency
of carbon/basalt/glass hybrid FRP
composite laminates
Chen, D
http://hdl.handle.net/10026.1/14734
10.1016/j.tws.2019.03.056
Thin-Walled Structures
Elsevier
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1
Flexural performance and cost efficiency of carbon/basalt/glass hybrid
FRP composite laminates
Dongdong Chen
1
, Guangyong Sun
1, 2,*
, Maozhou Meng
3
, Zhi Xiao
1
, Qing Li
2
1
State Key Laboratory of Advanced Design and Manufacture for Vehicle Body,
Hunan University, Changsha, 410082, China
2
School of Aerospace, Mechanical and Mechatronic Engineering, The University of
Sydney, Sydney, NSW 2006, Australia
3
School of Engineering, Plymouth University, Plymouth, United Kingdom
Abstract
This study investigates the interply hybridization of carbon fibre reinforced polymer
(CFRP) composite laminate to improve the flexural performance and cost efficiency. Carbon
layers were replaced partially by basalt and/or glass fibres to explore the effects of hybrid
ratio and stacking sequence on the flexural behaviour and material usage. Hybrid laminates
were manufactured by vacuum assisted resin transfer molding (VARTM) process. Three-point
bending tests were carried out to characterize the flexural properties and failure mechanisms
of the hybrid composite laminates. The fracture surfaces were examined by scanning electron
microscopy (SEM). The results showed that flexural strength and modulus of the hybrid
laminates decreased with the increase in the hybrid ratio of basalt fibres ranging from 0 to
50%; however negligible effects on flexural properties were observed when hybrid ratio
increased further up to 75%. A higher flexural modulus can be obtained by placing carbon
layers at both tensile and compressive sides symmetrically, and a higher flexural strength can
be achieved by placing basalt or glass fibre through a sandwich-like stacking sequence with a
hybrid ratio of 50%. The finite element modelling and classic laminate theory (CLT) analysis
were also conducted through validation against the experimental results, which enabled to
reveal the details of strain, damage and fracture subject to bending. The study showed a better
material efficiency for glass/carbon hybrid laminates in terms of strength/cost and
modulus/cost ratio; and the benefit of such cost efficiency of hybridization were discussed for
potential applications.
Keywords: Carbon fibre, basalt fibre, glass fibre, hybrid, flexural, classic laminate theory,
* Corresponding Author: Tel: +86-13786196408; Email: guangyong.sun@sydney.edu.au.
2
cohesive zone theory, finite element analysis
3
1. Introduction
Lightweight design is becoming more and more important, particularly in train, wind
energy and automotive industry, in which fibre reinforced polymer (FRP) composites have
been widely used thanks to its excellent strength to weight ratio, good fatigue resistance and
elevated chemical stability compared to traditional engineering materials[1-3]. Carbon fibre
reinforced polymer (CFRP) composites exhibit irreplaceability in a range of engineering
structures such as ships, sport equipment and aircraft, which have particularly higher
lightweight requirements [4-7]. However, its material and manufacturing cost largely restricts
its applications in traditional engineering field such as automobile industry [8, 9]. In the
meantime, CFRP composites are susceptible to stress concentration due to the inherent
brittleness. Even minor accidental impact or static overload could potentially cause the severe
damage to the structure, such as matrix cracking or delamination, sacrificing load carrying
capacity. Often, catastrophic failure can take place without sufficient warning due to the poor
residual strength [10].
A variety of strategies have been proposed to improve the brittleness of CFRP over
decades. One of the prevalent ways is to toughen the polymer matrix by adding nano-scale
reinforcement or to replace the thermosetting matrix with thermoplastics[11]. It has been
shown that the mechanical properties and multi-functionality of matrix can be improved by
adding a small amount of carbon nanotubes (i.e. 0.5wt %) [12, 13]. Thermoplastic matrices
exhibit appealing advantages to composite materials, including more environmental friendly
properties and recycling efficiencies [14, 15]. Compared to traditional thermoset resins,
thermoplastic matrix has been investigated and proven to be effective for improving
resistance to impact damage [16].
Hybridization with some high elongation fibres is an alternative way to improve the
performance of CFRP composites [11]. In this fashion, the advantages of carbon fibres can be
maintained whereas the disadvantages can be alleviated, and the material cost of carbon fibres
can be reduced by introducing low cost fibres. The toughness of composite can be improved
when the brittle carbon fibres are partially replaced by ductile fibres such as glass/basalt fibres
[9, 17]. In practice, fracture of brittle fibres in the hybrid composites can be used for health
monitoring purpose [18] or as a warning sign prior to final catastrophic failure [19]. From
material perspective, hybrid structural configurations can be categorized in three scales,
namely layer-by-layer, yarn-by-yarn and fibre-by-fibre [11]. The layer-by-layer technique has
exhibited its advantages on relatively lower cost of material by replacing high cost carbon
fibre with other lower ones.
Glass fibre has been considered to be an applicable hybrid material candidate due to its
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higher strain-to-failure quotient over the carbon fibre for unidirectional/woven composites [10,
17, 19-22], exhibiting enhanced strength and modulus of hybrid composite through a proper
stacking configuration of carbon and glass layers. Flexural properties of bidirectional hybrid
epoxy composites reinforced by E-glass and T700S carbon fibres with an inter-ply
configuration has been studied in [20], which showed the advantage of balancing 2-D flexural
properties for various loading directions. Kalantari et al. [21] conducted an optimal analysis
for unidirectional composite laminate hybrid with S-glass and T700S carbon fibre under
flexural loading; and interestingly, they found that the optimal configurations was not always
in the critical hybrid ratio with the maximum flexural strength or hybrid effect.
To further understand flexural behavior of laminated composites, substantial numerical
studies have been conducted in literature. For example, Meng et al. [23] investigated the
effects of carbon fibre layup on fracture initiation in laminated composites using
three-dimension (3D) finite element (FE) analysis and classic laminate theory (CLT), by
simulating damage initiation under bending. Ullah et al. [24, 25] introduced a cohesive zone
element in two-dimensional (2D) FE model for predicting the delamination behavior of
carbon/glass FRP composite under large-deflection bending, showing the capability of
modelling damage initiation and propagation. Jalalvand et al [26, 27] also used the cohesive
elements at the interface of carbon/glass fibre to model the delamination in the hybrid
laminates with different layup in tension. Dong and co-workers [28, 29] studied the effects of
flexural modulus, flexural strength and stress distribution of carbon/glass hybrid laminates in
their FE analyses. Note that there exist fairly complex failure mechanisms in the flexural
loading process of hybrid laminates that involves fibre fracture on the compressive side,
matrix crack and delamination etc. The effects of hybridization on flexural failure mechanism
have remained demanding and under-studied in literature to date.
Basalt fibre has been classified to be the material for military applications traditionally
and has been extensively used since its discovery [30]. Due to its redundant resource and
unique manufacturing process, basalt fibre is cheaper and more environment-friendly than
glass/carbon fibres [31]. Due to the low price and intermediate mechanical properties, one of
the potential applications of basalt fibre is to combine with other composite materials for
lightweight structures, enabling to reduce usage of CFRP while maintaining the high
mechanical properties. In several recent studies [9, 32-34], basalt fibre has been introduced as
a substitute of glass fibre to mix with carbon fibre. In this regard, the study was conducted on
tensile fatigue behavior of various fibre reinforced polymer composites, such as carbon, glass,
polyparaphenylenl benzobisoxazole (PBO), basalt fibre as well as the hybrid laminates with
carbon/glass and carbon/basalt fibres [35]. It was found that the fatigue resistance was
improved by using hybrid basalt/carbon fibres in comparison with net basalt fibre. The effect
