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Design of a lightweight heavy goods vehicle trailer

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Abstract and Figures

In road haulage the empty weight of a vehicle is a significant contributor to fuel consumption and resulting CO2 emissions. The application of lightweight materials in design is one avenue that needs to be explored in reducing the carbon footprint of road freight vehicles. There are very few regulations which determine the structural design of typical road freight semi-trailers, providing large scope for innovation in design. Composite trailers can combine aerodynamic and structural functions, leading to significantly reduced weight with improved performance. A review of previous lightweighting work, as well as, emissions modelling, collaboration with industrial partners and an analysis of UK road freight statistics has helped to identify double deck heavy goods vehicle trailers as one trailer type particularly suited to lightweighting from both economic and environmental standpoints. Drive cycle analysis has shown that reducing the empty weight of the double deck type trailer by 30% can reduce mass energy consumption index by 13% and moreover, decrease fuel consumption by approximately 2%. To achieve this targeted 30% weight reduction, structural design tasks have been split in two areas; adopting a 'clean slate' approach in the design of the whole trailer and applying composite solutions for specific components, such as trailer decking and side walls. Conceptual designs are being developed in collaboration with industrial partners with the aim of proving that lightweighting trailers with composites can be economically viable. In particular, a lightweight composite sandwich panel is being designed to replace existing hardwood deck materials currently used in trailers transporting grocery goods.
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© AET 2014 and contributors 1
DESIGN OF A LIGHTWEIGHT HEAVY GOODS VEHICLE TRAILER
Joel Galos, Dr Michael Sutcliffe and Prof David Cebon
University of Cambridge, Engineering Department
ABSTRACT
In road haulage the empty weight of a vehicle is a significant contributor to fuel
consumption and resulting CO2 emissions. The application of lightweight
materials in design is one avenue that needs to be explored in reducing the
carbon footprint of road freight vehicles. There are very few regulations which
determine the structural design of typical road freight semi-trailers, providing
large scope for innovation in design. Composite trailers can combine
aerodynamic and structural functions, leading to significantly reduced weight
with improved performance.
A review of previous lightweighting work, as well as, emissions modelling,
collaboration with industrial partners and an analysis of UK road freight
statistics has helped to identify double deck heavy goods vehicle trailers as one
trailer type particularly suited to lightweighting from both economic and
environmental standpoints. Drive cycle analysis has shown that reducing the
empty weight of the double deck type trailer by 30% can reduce mass energy
consumption index by 13% and moreover, decrease fuel consumption by
approximately 2%. To achieve this targeted 30% weight reduction, structural
design tasks have been split in two areas; adopting a 'clean slate' approach in
the design of the whole trailer and applying composite solutions for specific
components, such as trailer decking and side walls. Conceptual designs are
being developed in collaboration with industrial partners with the aim of proving
that lightweighting trailers with composites can be economically viable. In
particular, a lightweight composite sandwich panel is being designed to replace
existing hardwood deck materials currently used in trailers transporting grocery
goods.
1. INTRODUCTION
Road haulage is without doubt the most dominate medium for goods
transportation throughout the United Kingdom (UK) and there are no indications
of this changing in the foreseeable future. Moreover, predictions suggest that
road freight activity will remain of underlying importance to society and the
economy alike (Mckinnon, 2006). Road freight movement however is having an
adverse effect on the environment as it accounts for approximately 4.7% of the
UK’s carbon front print (“Transport Statistics Great Britain - GOV.UK,” n.d.).
© AET 2014 and contributors 2
New aggressive targets established by the UK government aim to drastically
reduce the emissions of greenhouse gases such as carbon dioxide (CO2) by
2050. Empty vehicle weight contributes significantly to vehicle fuel consumption
and CO2 emissions, therefore applying lightweight materials in the design of
these vehicles is one avenue that needs to be explored in reducing the carbon
foot print of the road freight industry.
There are very few regulations which determine the design of typical road
freight trailers. This provides a large scope for innovation within the design
process. The exception to this are vehicle and trailers that carry dangerous
goods (e.g. petroleum) as these are heavily regulated for safety purposes. The
limitations on typical trailers are mostly concerned with outside dimensions,
brake behaviour, tyre specifications and lighting requirements, rather than
structural performance. This means the structural design of the trailer is largely
unconstrained creating a window of opportunity for a ‘clean-slate’ type redesign
with the aim of significantly reducing empty weight. Replacing smaller
subcomponents within existing conventional trailer structures may also prove
to be a cost effective way to achieve lightweighting. Composite materials are a
good candidate for use in both the ‘clean-slate’ redesign and subcomponent
replacement approaches.
In recent decades the realisation of the advantages of replacing metal alloys
with composite materials has become prevalent across numerous industries
including aerospace, energy, high performance automotive and sporting goods.
The broad advantages of composite materials typically include; reduced weight,
increased corrosion resistance, greater fatigue life and reduced maintenance
requirements. However, the increased material and production costs
associated with composites often limits their application to high performance,
weight critical applications. As such, the increased cost associated with a
composite trailer should be carefully balanced alongside the economic benefits
that such a trailer can bring.
The major aim of this paper is to identify the road freight vehicles that are most
suited to lightweighting from both logistic and economic stand points. This is to
be achieved through a combination of: a review of previous composites
lightweighting work, emissions modelling, cost estimations, discussions with
industrial partners and an analysis of UK road freight statistics. The second
major aim of this paper is to recommend strategies in which trailer lightweighting
can be achieved, particularly through the application of composite materials.
© AET 2014 and contributors 3
The work presented in this paper represents a small part of the research that is
being performed at the Centre for Sustainable Road Freight, which is a
collaboration between Cambridge and Heriot Watt Universities and the road
freight transport industry. The Centre is also backed by a major five year grant
from the Engineering and Physical Sciences Research Council (EPSRC). The
main purpose of the Centre is to research engineering and organisational
solutions to make road freight economically, socially and environmentally
sustainable.
2. REVIEW OF SELECTED HOLISTIC COMPOSITE TRAILERS
The idea of applying lightweight materials in trailer design is not a new one.
Throughout the last decade there has been a growing appreciation of the
benefits brought from reducing the empty weight of road freight vehicles. This
appreciation has ultimately led to a growing trend of applying lightweight
composite materials in road freight vehicles and trailers. In assessing previous
attempts at using composites in road freight trailers, the past projects can be
classified in three broad areas; holistic trailer designs, subcomponent
approaches and other related heavy vehicle projects. Only the key works in
holistic trailer designs will be reviewed here. It should be noted that the
commercial nature of the majority of previous projects dictates that information
found in the public domain is often lacking technical details.
The Composittrailer commercialised in Belgium in 2000, represents one of the
first significant attempts at the creation of a trailer wholly from composite
materials. It is claimed that the 13.6m glass fibre reinforced polyurethane resin
chassis reduced the chassis weight from 3,500kg to 2,800kg, with the overall
trailer weight thought to be around 5,850kg. The design also employed moving-
floors as well as fireproof z-stitched composite sandwich panels (known as
Acrosoma Panels) used in the trailer side walls. The project also attempted a
staged integration of composites into a conventional trailer design; though this
was deemed unsuccessful as premature failure of metal subcomponents would
often result from dynamic loads and temperature fluctuations within the trailer.
After the initial release of the trailer, Martin Marietta Composites based in the
United States (US) attempted to adapt the concept for the North American
market. While it is believed the Belgian company sold around 40 lightweight
trailers, both the European and North American projects were eventually
abandoned. (“Introducing an affordable composite trailer to a conservative
market - Reinforced Plastics,” n.d.)
© AET 2014 and contributors 4
The ROADLITE Trailer developed by Nottingham University and EPL
Composites is another standout design that uses composites holistically
(Turner, M and Boyce, 2005). The flatbed trailer incorporates a 10m glass fibre
reinforced thermoplastic chassis with an integrated decking, while the first
prototype used a sandwich panel decking laid over the glass fibre chassis. The
trailer is reported to be approximately 20% lighter and 18% stiffer than the
conventional steel based design. Low cost composites and processing
techniques were targeted throughout the design in order to try to achieve a
competitive position within the market. While it is claimed that the trailer can
have an economic payback period of within two years, it is yet to be
commercialised, again indicating the reluctance of the market to accept a wholly
composite trailer. Similar to the ROADLITE trailer is the 13.6m flatbed
CleanMould trailer developed by six collaborators, including EPL composites,
as a follow-up to the ROADLITE project (Development of Lightweight,
Recyclable Thermoplastic Composite Semi-trailer and Boat Hulls with
Enhanced Performance. Publishable Final Activity Report D27 Final Project
Report., 2010). The program which concluded in 2010 developed a novel glass
fibre reinforced thermoplastic material which combined a low viscosity resin and
high fibre content continuous fibre reinforcement. The recyclability of this
material features prominently in the marketing of the trailer, as this is often a
drawback for many composite materials. It is reported that the design is
approximately 10% lighter than its steel counterpart and more aerodynamic,
giving rise to a reduction in fuel consumption by over 10%. However, the stated
benefits of the CleanMould trailer, like other composite trailers, are difficult to
validate and this likely plays a role in the reluctance of market acceptance.
German-based ‘The Team Technology’ (TTT) Composite AG designed a
carbon fibre / epoxy based monocoque triaxle curtain side trailer known as
Phoenixx (“A composite glimpse of the future,” 2006). The trailer was designed
and developed for German trailer manufacturer Kogel and was produced with
manufacturing support from CarboTech, based in Salzburg, Germany. It was
reported that the unladen weight of the trailer is 3,700kg, significantly lighter
than a conventional design of the same size which would weigh in the vicinity
of 5,500kg. The design incorporates a carbon fibre reinforced epoxy
monocoque chassis, an opening roof, a single side post and pneumatic legs.
Its format is most suited to the haulage of palletised goods. Kogel has
suggested that the production costs of the trailer are double that of a similar
steel trailer and approximately 30% greater than an equivalent aluminium
trailer. Similarly, though more recently in 2014, American retailer Walmart
collaborated with trailer manufacture Great Dane Trailers to create a prototype
© AET 2014 and contributors 5
trailer made wholly of carbon fibre composite. The trailer incorporates two 16m
long side panels that are made from a single sheet of carbon fibre. It is claimed
that the trailer is 1814kg lighter than a comparable conventional trailer
(“Walmart uses CFRP to boost efficiency: CompositesWorld,” n.d.).
Composites have also been applied holistically in the design of numerous
refrigerated trailers. In 2010, TTT Composite AG released a 13.6m refrigerated
trailer for use by German retail chain Aldi. The trailer had a monocoque design
that was built around an epoxy based carbon fibre reinforced plastic (CFRP)
chassis (Kaiser, 2010). The design reduced the empty weight of the trailer by
around 33% in comparison to a conventional refrigerated trailer of the same
size. This reportedly led to a 30% reduction in fuel consumption and a 15%
reduction in CO2 emissions. The production costs however were reported to be
in the order of 30% more than the conventional trailer. Similar to the Aldi trailer
is the lightweight refrigerated GIGA trailer manufactured by Dutch company
Talson Transport Engineering. The GIGA trailer uses a self-supporting structure
based on a closed torsion free structure without a chassis and has been
especially designed for carrying cooled mega volume airfreight. The stated
benefits of the GIGA trailer are similar to those reported by the Aldi trailer
(“Lightweight Structures B.V. | Lightweight GIGA trailer,” n.d.).
Apart from being used to lightweight dry and refrigerated trailers, composites
have also been used by multiple companies to create lightweight tankers. The
most notable of these is the Omni Tanker designed and manufactured by
Australian company Evolution Tankers Pty Ltd. The tanks are comprised of a
foam sandwich construction with high density structural foam separating inner
and outer carbon fibre laminates. The tanks also have a polyethylene
thermoplastic interior to increase chemical resistance and have an exterior gel
coat finish to provide a smooth polished surface. The tanks are built for a wide
number of tractor-trailer combinations including small rigid vehicles, triaxle
trailers, B-double and road train configurations. Like more conventional steel or
aluminium tankers, the Omni uses a compartment design with compartment
capacities varying from 6,00L to 8,500L. These tankers have been designed
and built to the Australian Dangerous Goods code ADG7, as well as Australian
Standards AS2809 and AS2634 (“Setting the Benchmark for Chemical
Transport Tankers,” n.d.). Similar to the Omni tanker is the tippable composite
cylindrical tanker made by French company Spitzer-Eurovrac. This tanker uses
numerous carbon fibre and glass fibre reinforced composites in the design of
the tippable vessel. It is claimed that the tank is 400kg lighter than comparable
aluminium tankers and is able to carry the same materials. The tank has been
© AET 2014 and contributors 6
granted French type approval, and five prototypes have been built, though it is
believed that no significant sales breakthroughs have been made (“A composite
glimpse of the future,” 2006).
Prior to releasing the Phoenixx carbon fibre trailer mentioned earlier, TTT
Composites AG designed a carbon fibre based monocoque tipper (“A
composite glimpse of the future,” 2006). The tipper was manufactured with the
help of German based bodybuilder Meierling. The tipper has a standard
capacity of 25m3 and an unladen weight of 3,600kg, significantly lighter than
conventional steel and aluminium tippers. The tipper was launched at the 2004
Hanover show and has been tested over several years carrying sand and stone,
showing no major issue with operational wear. More recently than the TTT
tipper, a collection of Dutch companies collaborating with ComposiTTransport
have developed a carbon fibre reinforced thermoplastic based composite tipper
trailer known as Fiby tipper (“ComposiTTransport,” n.d.). It is reported to be up
to 50% lighter than comparable steel loading bins. This is a large type tipper,
with a capacity of around 32.5 m3, and like the TTT designed tipper, it has been
designed to haul bulk products such as sand, gravel and agricultural products.
The Fiby tipper is the first product from ComposiTTransport which aim to open
an automated factory in the Netherlands in 2015 to produce a range of variety
of thermoplastic based products including: tippers (articulated and rigid), trailer
chassis, container tanks, truck wheels, tanks, inland waterway vessels and salt
dispersers. ComposiTTransport believe they can reduce commercial risk by
producing a variety of composite structures from the same factory and they
estimate the demand for lightweight tippers alone to be at least 1,000 units
(“ComposiTTransport,” n.d.).
It is interesting to note that the majority of these previous composite trailer
projects have been built with the mainland European market primarily in mind.
This market does not permit the use of double deck type trailers due to poor
height clearance in tunnels and under bridges on continental roads. This most
likely led the projects to not even consider a lightweight redesign of the double
deck trailer.
3. IDENTIFICATION OF TRAILERS SUITED TO LIGHTWEIGHTING
The range of previous trailer lightweighting projects discussed in section 2
suggests that there is a good variety of trailer types that can benefit from
lightweighting, though in all cases, mass-limited HGV operations stand to
benefit the most. Calculating the energy consumption reductions brought from
© AET 2014 and contributors 7
lightweighting and examining the key logistical factors in road freight operations
will also help in identifying trailers that are suited to lightweighting.
3.1. Energy Consumption Reductions from Lightweighting through Idealised
Drive Cycle Analysis
An idealised tractive energy analysis over idealised drive cycles has been
performed to further clarify the effects trailer weight reduction can have on
energy consumption in the case of mass limited vehicles. This is achieved by
first considering a simple force balance on a vehicle traveling on a straight and
level road as shown below.
Figure 1: Free body diagram of a lorry travelling along a straight level road.
A force balance yields the following formula for tractive force:
   


  

Tractive power is determined by multiplying tractive force by the vehicle
velocity:

 

Integration of tractive power over idealised drive cycles yields the tractive
energy required to travel distance, s, in that time:
   

  

 

The corresponding litres of fuel burnt for the journey can then be estimated by
multiplying the total change in the tractive energy by the inverse of the lower
heating value of diesel. The engine and transmission efficiencies are also
© AET 2014 and contributors 8
accounted for. The effect of gear ratios has been neglected for this simple
comparative analysis. The engineering constants used in this analysis are
defined in table 1.
 
 
Table 1: Engineering constants used in the drive cycle analysis.
engine =
0.4
Efficiency of engine (Laclair, 2011)
transmission =
0.9
Efficiency of transmission (Laclair,
2011)
LHV (J/L) =
35,500,000
Lower Heating Value of diesel
(Laclair, 2011)
CRR =
0.0066
Coefficient of rolling resistance
(Odhams et al., 2010)
CO2 emissions
(kg/L) =
2.614
CO2 released during diesel
combustion (“Carbon emissions of
different fuels,” 2011)
ρ (kg/m3) =
1.225
Density of air at sea level (Odhams
et al., 2010)
It is assumed that each vehicle makes one outbound haul where is it fully laden
(load factor, LF = 1), and one return journey where the vehicle is partially back
loaded (LF = 0.3), giving an average load factor of 0.65. This level of
backhauling is in line with typical load factors reported by hauliers of groceries
and consumer goods. The tractive energy analysis is performed for each type
vehicle (table 2) over 10km idealised drive cycles adapted from (Odhams et al.,
2010), as defined in figures 2 and 3.
© AET 2014 and contributors 9
Table 2: Vehicle properties used in drive cycle analysis. Note: the lightweight
trailers are assumed to be 30% lighter than the standard trailers.
Figure 2: Idealised ‘semi-urban’ drive cycle adapted from (Odhams et al.,
2010).
0
50
100
0 100 200 300 400 500 600
Vehicle Speed
(km/h)
Time (sec)
Vehicle
Type
Type of
Drive
Cycle
Applied
Tractor
Weight
(kg)
Max
GVW
(tonnes)
Standard
Trailer
Weight
(kg)
Light
Trailer
Weight
(kg)
8m curtain
side
semi
urban
3.95
5,000
26
5,900
4,130
10m curtain
side
long
haul
6.62
6,700
30
7,000
4,900
13.6m
curtain side
long
haul
6.62
6,700
44
8,200
5,740
13.6m
curtain side
double deck
long
haul
6.62
6,700
44
10,900
7,630
8m
refrigerated
semi
urban
3.95
5,000
26
7,400
5,180
10m
refrigerated
long
haul
6.62
6,700
30
8,400
5,880
13.6m
refrigerated
long
haul
6.62
6,700
44
10,200
7,140
13.6m
refrigerated
double deck
long
haul
6.62
6,700
44
12,900
9,030
12.7m fuel
tanker
semi
urban
6.62
6,700
44
7,400
5,180
© AET 2014 and contributors 10
Figure 3: Idealised ‘long haul’ drive cycle adapted from (Odhams et al.,
2010).
It can be seen from figure 4 that for every vehicle type, a decrease in fuel
consumption of approximately 2% is observed for the 30% lighter trailer. Note
that fuel consumption is assumed to be zero during deceleration. Reductions in
energy consumption are found to vary from approximately 8% to 16%. This
shows that lightweighting can bring significant fuel and energy consumption
savings for all HGVs, should they be limited by weight. Note that the decrease
in energy consumption refers to mass energy performance index (EIm), which
has units of kJ/tonne.km and is defined as:

 
Figure 4: Reduction in energy consumption index (EIm) and increase in MPG
that result from trailer lightweighting by 30%, as estimated through idealised
drive cycle analysis.
0
50
100
0 100 200 300 400 500
Vehicle Speed
(km/h)
Time (sec)
0%
2%
4%
6%
8%
10%
12%
14%
16%
18% Decrease in
energy
consumption
Increase in
MPG
© AET 2014 and contributors 11
3.2 Key Logistical Factors in Road Freight Operations
In most developed economies such as the UK, operations are typically limited
by volume rather that gross vehicle weight (GVW) or weight over axle. This is
highlighted by figure 5 which shows data for the UK. This is largely attributed to
the fact that the majority of vehicles move low density fast moving consumer
goods (FMCGs). The average density of products that are commonly moved by
HGVs are shown in figure 6.
Figure 5: Percentage of weight and volume constrained operations in the UK
adapted from (Mckinnon, 2010).
Figure 6: Approximate densities for a range of common payloads adapted
from (Glaeser, 1995).
0%
10%
20%
30%
40%
50%
60%
70%
Drawbar Artic 32-38T Artic >38T
Weight-constrained Volume-constrained
0
1
2
3
4
5
6
7
8
9
Typical density (tonnes/m3)
Optimum density
to fill 40 tonne
© AET 2014 and contributors 12
As mentioned previously; the economic and environmental gains from
lightweighting will only become relevant in weight-limited applications, as the
relative benefits will diminish and become far less quantifiable in operations that
are limited by volume. Hence, it is proposed that the success of a lightweight
trailer will depend on identifying appropriate sectors of the road freight industry
which frequently weight-out. Figure 6 indicates that vehicles carrying dense
bulk products such as metals, concrete and soil are likely to be weight-limited.
However, the low value nature of these products will quite probably generate
longer payback periods for any novel lightweight technologies compared to
other higher value products such as groceries and fuel. Minimising the payback
period is a critical step in gaining industry acceptance for lightweight
technologies.
A statistical study of the HGV fleet used in grocery distribution by one large
supermarket chain has identified double deck trailers as being particularly
constrained by weight; in particular weight over axle. This can be seen in figure
7, where trailer axle weight is the variable that operates closest to its maximum
allowable value of eight tonnes. In contrast to this, other trailer types were found
to be operating far from their maximum allowable weight limits and were more
likely to be restricted by volume (number of cages).
Figure 7: Probability distributions (with kernel smoothing function applied) for
the axle weight, gross vehicle weight and cage load of triaxle double deck
trailers used by a large supermarket chain in grocery distribution. Dashed
lines indicate maximum allowable values. Sample size = 188.
Other research has suggested that numerous companies within the UK are
looking to increase vehicle utilisation through the continued and potentially
growing investment in double deck trailers (Piecyk, 2010). This again suggests
that double deck trailers are a good candidate for lightweighting.
© AET 2014 and contributors 13
4. TARGETED LIGHTWEIGHT SOLUTIONS
Strategies for applying composites to the HGV trailers can be split into two
broad categories; adopting a 'clean-slate' approach for the whole trailer and
identifying composite solutions for specific components. For both these
strategies to reach the point where they can be implemented in industry, they
need to be largely driven by cost. It is believed that the most successful
composite solutions will strike a balance between cost, performance and weight
reduction.
4.1. ‘Clean-Slate’ Composite Re-Design
Adopting a ‘clean-slate’ design approach will allow for the full benefits of
composite materials to be realised. This approach can help allow for the
integration of aerodynamic and structural functions, which can help achieve
weight reduction and aerodynamic improvement simultaneously. Moreover, the
directional nature of composites can be exploited to increase structural
reinforcement at areas of high stress concentration and remove mass in parts
of the structure that are not significantly loaded. The ‘clean-slate’ approach
would also allow for the integration of composite materials with other emerging
HGV technologies such as active steering of trailer wheels which has been
shown to reduce lateral design loads (Jujnovich, Roebuck, & Cebon, 2008).
Section 2 and section 3 of this report have identified double deck trailers as
being one good candidate for a ‘clean-slate’ re-design.
The previous composite trailers that have adopted a ‘clean-slate’ design
approach suggest that the major drawback in this approach is increased
material and production costs associated with composites. In particular, the
resin transfer moulding (RTM) process (used to manufacture the
Composittrailer, ROADLITE trailer and CleanMould trailer) is very unlikely to be
adopted by existing trailer manufacturers. Adopting this process would require
significant investment in new equipment and facilities, as well as extensive
operator training. Likewise with the carbon fibre based Phoenixx and Walmart
trailers which require an autoclave to cure carbon fibre components. Perhaps
the most financially viable way of achieving a composite redesign is to
outsource the manufacture of composite components and then integrate these
components in existing trailer assembly lines. This would require minimum
investment costs in, equipment, facilities and operator retraining.
Pultrusion processing has been identified as a cost effective manufacturing
technique that is suited to the development of a composite trailer and as such
© AET 2014 and contributors 14
will be the subject of further investigation. Pultruded deck sections (currently
successfully used in pedestrian and road bridges) can provide a sensible start
point for the introduction of pultruded composites into trailers. Hence, pultruded
deck sections will undergo mechanical testing with the aim of showing that
pultruded composites are appropriate for use in HGV trailer decks. Holistic
pultrusion based concept trailer designs are to developed and refined with
guidance from industrial partners to ensure they are developed with
manufacturability and end-use in mind. Finite element analysis and fatigue
testing of a critical component, such as the gooseneck, of the most prudent
conceptual design will help to demonstrate pultrusions are appropriate for use
in large structural components of HGV trailers.
4.2. Staged Integration of Composite Subcomponents
Examining the current structural design of a typical 13.6m curtain side trailer, it
is immediately obvious there are many opportunities for composite
subcomponent replacement. The subcomponents that are particularly good
candidates for lightweighting include: side walls, running gear, wheels, chassis
members, suspension bracing, barn doors, decking and the roof structure.
Many operators are known for their poor treatment of steel rubbing plates
making them a poor candidate for composite substitution. Retrofitting of
structural components is most likely not viable, however retrofitting of easily
interchangeable sub components, such as side walls and decking, might be
viable should the gains be immediate. Replacing conventional hardwood based
decking with a lightweight composite sandwich panel has been determined to
be a promising approach and as such is the focus of further research.
The integration of composites into conventional designs to-date has been
restricted by numerous factors. For example, a mismatch in stiffness between
composites and steel leads to high stress zones developing under torsion loads
typically seen in-service. High stress areas include areas around the kingpin
and neck toward the front of the trailer, as well as areas around the suspension
toward the rear of the trailer that see high loadings from tyre scrubbing.
Difficulties with bonding to metal railings, temperature requirements of
adhesives during cure, as well as difficulties in the repairability of bonded joints,
have all restricted the applications of adhesively bonded composite solutions.
End-of-life considerations are also of utmost importance. Because trailers have
to be returned to the manufacturer for recycling, steel and wood are more
desirable than composites from a recyclability stand point.
© AET 2014 and contributors 15
5. CONCLUSIONS
While previous composite trailer projects have failed to gain any significant
market acceptance, composites are poised to be used to good effect in the
design HGV trailers. Lightweighting through the application of composites in
HGV trailers used in mass-limited operations can bring significant fuel and
energy consumption savings, leading to a reduction in both operation costs and
carbon footprint. Double deck trailers are in particular one trailer type that stand
to benefit from lightweighting. Applying composites in a ‘clean-slate’ redesign
of a trailer will allow for significant weight reductions, though will involve a
relatively long time frame to successfully implement. Applying composites to
trailer subcomponents such decking and side walls can be implement in a much
shorter time frame than a re-design, though the benefits will be significantly
less. In both cases, low cost manufacturing techniques such as pultrusion
processing should be targeted to help achieve minimal increase in material and
production costs. It is evident that the most successful composite solutions for
HGV trailers will strike a balance between cost, performance and weight
reduction.
ACKNLOWEDGEMENTS
The authors would like to acknowledge the financial support from the members
of the Centre for Sustainable Road Freight and from the EPSRC. Thanks are
also due to Mr. T. Sturgess at SDC Trailers Ltd for his continued assistance.
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... Since empty vehicle weight contributes significantly to overall vehicle weight, it is a contributor to fuel consumption and CO 2 emissions. Therefore, using lightweight materials and structural optimization in design should be explored in identifying ways to reduce the carbon footprint of the road freight industry as a whole [2,3]. ...
... This approach provides a clarification on the weight reduction limits that could be achieved through various lightweighting strategies. This study builds on previous research on lightweighting European-style truck trailers through fleet case studies, subcomponent replacement, and lightweight chassis design [2,3,4,5,10,11,12]. The study of composite solutions for trailers presented by the authors in [12] has been extended to include shape optimization of existing metal I-beams and the application of GFRP pultrusions as chassis beams. ...
... Chassis: steel beams and hardwood decking replaced with holistic composite structure Side walls: plywood panels replaced with composite sandwich panels Chassis: shape optimization of logitudinal steel I-beamsRunning gear: three axle steel system replaced with three axle GFRP system Chassis: transverse aluminum members replaced with GFRP pultrusions Decking: hardwood replaced with composite sandwich panel Wheels: steel wheels (×6) replaced with CFRP wheels Barn doors: plywood-metal panels replaced with composite sandwich panels FIGURE 11 Summary of estimates of potential weight-saving opportunities from various lightweighting strategies for a 13.5 m European-style trailer. Red bars indicate results developed within the present study; blue bars represent findings from previous studies[2,3,4,5,10,11,12]. ...
Article
This paper investigates options for light-weighting truck trailers through a combination of material selection and structural optimisation. Critical chassis design load cases were established, and a parametric finite element model of a typical European-style 13.5 m long truck trailer built from steel I-beams was developed. The model has been used to show that existing longitudinal steel I-beams could be reduced in weight by 28% (140 kg) through shape optimisation alone. The model was expanded to analyse holistic composite trailer structures. It showed that up to 67% (1,326 kg) of weight could be saved by executing shape and material optimisation in unison. The approach highlights that design through parametric analysis allows for many different structural configurations to be assessed in terms of both mechanical performance and material cost. This facilitates the construction of a theoretical design space of a lightweight chassis, clarifying the weight reduction limits that could be achieved with lightweight materials and structural optimisation. The lightweight trailer chassis designs proposed here are also compared against a portfolio of shorter-term strategies for trailer light-weighting. These strategies are poised to have an increasingly important role in reducing the greenhouse gas emissions of the road freight industry.
... Total deformation of C section 16 5. 4 Total deformation of I section 16 5. 5 Von mises strain of C section 17 5. 6 Von mises strain of I section 17 5.7 ...
... Modal analysis of C section 24 6. 2 Modal analysis for C section Graph 25 6. 3 Frequencies of C section 25 6.4 Modal analysis of I section 26 6. 5 Frequencies of I Section 26 6. 6 Modal analysis of I section Graph 27 viii ...
Thesis
Full-text available
In the present project work, static and dynamic analysis of both C and I sections of tractor trolley chassis is performed using Finite Element Analysis. The 3D finite element model of the chassis is achieved through Nx CAD software. Later, the finite element model of the chassis is imported to ANSYS. The Finite Element Analysis is carried out in commercial finite element software named ANSYS. By conducting the static structural analysis of the finite element model of the chassis in ANSYS, deflection, Von Mises stress, Normal stress, shear stresses are found out for both C and I sections. Dynamic analysis is also performed on the finite element model of the chassis with C and I sections and natural frequencies are found out. Comparison of the results of the static and dynamic analysis for both C and I sections of the chassis is presented. From this comparison, the optimum shape of cross section of chassis is suggested.
... The main requirement of a subsurface imaging trailer is being lightweight. It can be noted that the application of lightweight materials in designing a trailer is not a new idea because of the growing benefits such as reduction on operating costs and carbon footprint as well as fuel and energy consumption [9]. The 60% of the total weight of the trailer is based on the material used in the body and chassis components [8]. ...
... Thus, weight has been one of the dominant factors considered in eliminating other alternatives in the initial selection. While there are many functional materials [8][9]18] closely fit for an underground imaging application, their availability is another thing. This sub-criteria refers to the material capability to be available whenever it is needed for production or product assembly. ...
Conference Paper
Underground imaging technology has been functional in the detection of utilities in the subsurface through land surveying. One way to ensure the quality gathering of data is to identify the best material that can be used for its trailer as it will undergo chaotic movements when used in uneven terrain. Material selection is a vital part of any design process and product development. Thus, this study contributes to the development of an underground imaging system body trailer by using Analytical Hierarchical Process in material selection. AHP technique was employed in structuring multi-criteria decision-making problems by weighting and ranking criteria such as mechanical properties, material quality characteristics, and manufacturing considerations in respect to their corresponding sub-criteria and alternatives. Mild carbon steel, galvanized iron, polypropylene, and cold-rolled steel are the materials assigned as alternatives. Survey form containing the pairwise comparison competing criteria, sub-criteria, and alternatives were given to target respondents as decision makers. Furthermore, the utilized AHP calculator was used for all the computations for consistency analysis. Based on the results, mild carbon steel is the most suitable material to be used as the core material in the fabrication of the underground imaging trailer body. It obtained the highest score in total weight ranking alternatives with a 0.269 weight value surpassing the galvanized iron, cold-rolled steel, and polypropylene with 0.198, 0.180, and 0.104 weight values, respectively.
Article
The copyright in this thesis is owned by the author. Any quotation from the thesis or use of any of the information contained in it must acknowledge this thesis as the source of the quotation or information.
Article
This report addresses the approach that will be used in the Large Scale Duty Cycle (LSDC) project to evaluate the fuel savings potential of various truck efficiency technologies. The methods and equations used for performing the tractive energy evaluations are presented and the calculation approach is described. Several representative results for individual duty cycle segments are presented to demonstrate the approach and the significance of this analysis for the project. The report is divided into four sections, including an initial brief overview of the LSDC project and its current status. In the second section of the report, the concepts that form the basis of the analysis are presented through a discussion of basic principles pertaining to tractive energy and the role of tractive energy in relation to other losses on the vehicle. In the third section, the approach used for the analysis is formalized and the equations used in the analysis are presented. In the fourth section, results from the analysis for a set of individual duty cycle measurements are presented and different types of drive cycles are discussed relative to the fuel savings potential that specific technologies could bring if these drive cycles were representative of the use of a given vehicle or trucking application. Additionally, the calculation of vehicle mass from measured torque and speed data is presented and the accuracy of the approach is demonstrated.
Article
Key factors that influence the energy consumption of heavy goods vehicles are investigated. These factors include engine efficiency, aerodynamic drag and rolling resistance, vehicle configuration (number of vehicle units), traffic congestion, speed, payload factors, and the use of regenerative braking. An accurate, validated model of the fuel consumption of a 38 tonne tractor-semitrailer vehicle is used as a basis to derive fuel consumption models of a number of other vehicle configurations. These models included a rigid four-axle truck with maximum gross vehicle mass (GVM) of 26 tonnes; a six-axle tractor semitrailer with GVM of 44 tonnes, with and without regenerative braking; a ‘B-double’ with GVM of 60 tonnes; and an ‘A-double’ with GVM of 82 tonnes. These vehicle models were driven over a simple hypothetical drive cycle with a fixed maximum speed and varying numbers of stops in a 10 km stretch of road. It is concluded that: (a) improving engine efficiency, unladen mass, rolling resistance, and aerodynamic drag can yield relatively small improvements in fuel consumption, compared with other factors; (b) larger vehicles are always significantly more energy-efficient than smaller ones when fully loaded; (c) transferring freight from articulated vehicles to smaller rigid vehicles for urban deliveries typically increases fuel consumption by approximately 35 per cent; (d) running vehicles partially loaded can increase the energy per unit freight task by up to 65 per cent; and (e) under urban start—stop conditions, the use of regenerative braking systems can reduce heavy vehicle fuel consumption by 25–35 per cent.
Article
A new active steering controller was developed for articulated heavy goods vehicles. It was designed to achieve 'perfect' path-following under all conditions. An experimental triaxle trailer, with three actively-steered axles was built and used to compare the performance of the new controller with a passive 'command steer' steering strategy, and a conventional trailer with fixed axles. A novel system of digital cameras was used to measure the line following performance of the vehicle. The path-following control strategy showed reductions of cut-in (79%), tail swing (100%), exit settling distance (97%) and lateral tyre force (83%) relative to the unsteered case, and 48%, 100%, 93%, and 64% respectively relative to the command steer case.
Article
Twice over the past 30 years Britain has suffered severe paralysis of its road freight system. This paper explores the likely consequences of a complete cessation of trucking services over the period of a week. By analysing inventory levels, lead times, dependence on road transport and opportunities for substitution in critical sectors, it forecasts a rapid rate of economic collapse.
Performance of articulated vehicles and road trains regarding road damage and load capacity
  • K.-P Glaeser
Glaeser, K.-P. (1995). Performance of articulated vehicles and road trains regarding road damage and load capacity.
Thermosets and thermoplastics set to compete for composite trailer market. European Plastics News
  • R Kaiser
Kaiser, R. (2010, December). Thermosets and thermoplastics set to compete for composite trailer market. European Plastics News, 14–15. Retrieved from http://www.avk-tv.de/files/pressclip/avk- pc/20101220_thermosets_and_thermoplastics_set_to_compete_for_composit e_trailer.pdf
Large Scale Duty Cycle (LSDC) Project: Tractive Energy Analysis Methodology and Results from Long-Haul Truck Drive Cycle Evaluations (p. 32) Retrieved from http://info.ornl.gov/sites/publications/files/Pub33189.pdf Lightweight Structures B.V. | Lightweight GIGA trailer
  • T Laclair
Laclair, T. (2011). Large Scale Duty Cycle (LSDC) Project: Tractive Energy Analysis Methodology and Results from Long-Haul Truck Drive Cycle Evaluations (p. 32). Retrieved from http://info.ornl.gov/sites/publications/files/Pub33189.pdf Lightweight Structures B.V. | Lightweight GIGA trailer. (n.d.). Retrieved July 31, 2014, from http://www.lightweight-structures.com/lightweight-gigatrailer/index.html
Green Logistics: Improving the Environmental Sustainability of Logistics
  • A Mckinnon
Mckinnon, A. (2010). Green Logistics: Improving the Environmental Sustainability of Logistics (1st ed.). London: Kogan Page.
Thermosets and thermoplastics set to compete for composite trailer market
  • R Kaiser
Kaiser, R. (2010, December). Thermosets and thermoplastics set to compete for composite trailer market. European Plastics News, 14-15. Retrieved from http://www.avk-tv.de/files/pressclip/avkpc/20101220_thermosets_and_thermoplastics_set_to_compete_for_composit