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The potential for lightweighting of railway axles was investigated to primarily reduce the unsprung mass of a rail vehicle. The reduction of unsprung mass equates to an overall lighter train which will help to reduce track damage, energy consumption and total operating costs. This work was performed within the NEXTGEAR project which is ascribed under the Shift2Rail program. This paper focusses on the design of a composite railway axle as part of the “Wheelset of the future” Work Package 3. A parametric study is presented for the sizing of one of the design concepts (the full-length pre-manufactured tube axle) that shows the greatest potential for mass reduction. This study uses the existing hollow steel axle as a benchmark for mass, strength and stiffness. The estimated mass of this composite axle is 50 kg. This represents an estimated mass reduction of 75% compared to the existing hollow steel axle.

The use of fibre reinforced composite materials is one method by which the lightweighting of rail vehicles can be achieved. However, the issue of impact damage, amongst other challenges, limits their safety certification. This issue is accentuated by the high levels of loading a rail vehicle may be subjected to during service. This paper addresses the significance of pre-tension on large composite structures, specifically for a composite redesign of a pressure vessel for a freight tank wagon. Preloading was determined to be detrimental to the overall impact resistance of a large composite vessel. At 15.71 J of impact energy, there was a 22% increase in mean absorbed energy for a uniaxially loaded panel over an unloaded panel. However, there was only a 4% difference in penetration depth between uniaxial and biaxial loading. A novel finding from these results is that the effects of preloading are more profound if the loading does not act parallel to a principal fibre direction. Matrix cracking and delaminations are the most common failure modes observed for specimens under low-velocity impact and are intensified by preload.

The rising economic and environmental pressures associated with the generation and consumption of energy necessitates the need for lightweighting of railway vehicles. The railway axle is a prime candidate for lightweighting of the unsprung mass. The reduction of unsprung mass correlates to reduced track damage, energy consumption and total operating costs. This paper presents the design of a lightweight multifunctional hybrid metallic-composite railway axle utilising coaxial skins. The lightweight axle assembly comprises a carbon fibre reinforced polymer composite tube with steel stub axles bonded into either end. The structural hybrid metallic-composite railway axle is surrounded by coaxial skins each performing a specific function to meet the secondary requirements. A parametric sizing study is conducted to explore the sensitivity of the design parameters of the composite tube and the stub axle interaction through the adhesive joint. The optimised design parameters of the axle consist of a, composite tube outer diameter of 225 mm, composite tube thickness of 7 mm, steel stub axle extension thickness of 10 mm and a bond overlap length of 100 mm. The optimised hybrid metallic-composite railway axle design concept has a mass of 200 kg representing a reduction of 50% over the solid steel version.

The adoption of multi-material lightweight structures has been recognized as one of the most effective and promising solutions to improve fuel efficiency and accelerate the electrification of future transportation systems. A wider application of multi-material lightweight structures has been limited by our capability to fabricate them reliably and cost-effectively at a commercial scale. In the last decade, many friction-based joining processes have been developed and demonstrated their advantages over mechanical fastening and adhesive bonding processes in fabricating future multi-material lightweight structures. This article provides a comprehensive review on the recent advances of five promising friction-based joining processes (friction assisted joining, friction lap welding, friction spot joining, friction riveting, and ultrasonic welding) on the aspects of facilities, joining process, joining mechanism, applicable materials, surface pretreatments, and the influence of process parameters on the performance of the produce joints. This article also provides a summary of the performance of the produced joints under static load, dynamic load, various thermal cycles, or harsh chemical environments. The main similarities and differences among the joining processes are discussed. The paper points out the main knowledge gaps that need to be filled and the research that needs to be conducted to further advance the joining process. This review article will place the friction-based joining process at a new starting point with accelerated developing speed towards higher technical maturity to make the processes available for certifiable industrial applications.

The goal of this study is to evaluate which improvements to car components can most reduce its environmental impacts, narrowing the field to only those currently available on the market. The strategy of the material substitution is the more investigated together with mass reduction, even if the study does not ignore marginally shape optimization, controls, and production processes. Another goal is to discriminate the environmental benefits according to the size of the car and power supply, i.e., gasoline, hybrid and electric. To ensure the reliability and the reproducibility of the results, the study was conducted using the Life Cycle Assessment (LCA) methodology, following the international standards ISO 14040/44, limited to the determination of CO2 eq. Each considered datum was extracted from scientific papers and used within a rigorous structured methodology to calculate the environmental impacts for all the types of car. The functional unit was defined to refer the environmental benefits arising from each improvement of the components to the impacts of the car life cycle normalized for a distance travelled of 100 km in a typical European route. Overall, a reduction in overall car impacts between 7% and 14% was determined by combining all the best alternatives for each analysed component. The major advantage was guaranteed to internal combustion cars and minor to electric cars, while in terms of size, small car benefitted the most. Frame improvement alone provided 51% of the total impact reduction, followed at a distance by that on the bodywork. In conclusion, the study showed how the followed approach can be useful to combine a large amount of different and heterogeneous data while extracting general considerations for automotive eco-design. The structural lightning achieved through material substitution has been fundamental to reduce fuel and energy consumption, and therefore the impacts of the use phase. However, the moderate lightning ensured by aluminium is better than the larger one of carbon fiber and magnesium, whose greater impacts in material extraction, manufacturing, and end-of-life compromise their most sustainable use phase. A further investigation should be deserved to increase control over vehicle condition and driving patterns which resulted valuable options.

The paper presents an innovative lightweight design solution for the rear crash management system of a C-class car, developed within the AffordabLe LIghtweight Automobiles AlliaNCE (ALLIANCE) EU research project. The innovation provides that the reference version of the module, based on conventional steel components, is revolutionized through the introduction of extruded 6000/7000 series aluminum alloys. The two competing alternatives are described and compared in relation to design and technological solutions, including also a sustainability analysis which assesses the entire Life Cycle (LC) of the system on the basis of a wide range of environmental indicators. The lightweight solution allows achieving a large mass reduction (almost 40%), while providing improvements in terms of strength, production efficiency and design freedom. On the other hand, the introduction of new materials and manufacturing technologies entails contrasting sustainability effects depending on impact category, thus not allowing to affirm that the novel alternative is unequivocally preferable under the environmental point of view. However, the comprehensive evaluation of all sustainability aspects through a multi-criteria decision analysis (TOPSIS method) reveals that the environmental profile of the innovative design is slightly preferable with respect to the conventional one.

A thorough assessment of Life-Cycle effects involved by vehicle lightweighting needs a rigorous evaluation of mass-induced consumption, on which energy and sustainability benefits during use stage directly depend. The paper proposes an analytical calculation procedure to estimate the weight-related energy consumption of pure Electric Vehicles (EVs), since existing literature leaves considerable room for improvement regarding this research area. The correlation between consumption and mass is expressed through the Energy Reduction Value (ERV) coefficient, which quantifies the specific consumption saving achievable through 100 kg mass reduction. The ERV is estimated for a number of heterogeneous case studies derived from real 2019 European market EV models and according to three drive cycles, to consider different driving behaviors. For the case studies under consideration, ERV ranges from 0.47 to 1.17 kWh/(100 km × 100 kg), with the variability mainly depending on vehicle size and driving cycle. Given the high uncertainty of mass-related consumption on car size, an analytical method is refined to estimate accurately the ERV for any real-world EV model, starting from vehicle technical features. Along with energy assessment, the research also evaluates the environmental implications of lightweight design by means of the Impact Reduction Value (IRV), which is estimated for three distinct electricity grid mixes. Finally, the ERV/IRV modeling approach is applied to a series of comparative lightweight case studies taken from the literature. Such an application demonstrates the effective utility of the work to reduce the uncertainty for all cases where no physical tests or computer-aided simulations are available.

Lightweighting is a design strategy to reduce energy consumption through the reduction of mass of a product. Lightweighting can be applied to machine tools to reduce the amount of energy consumed during the use phase. Thus, the energy cost of machine operation will be reduced. One might also hypothesize that since a lighter-weight machine tool requires less material to build, the cost to produce such a machine will be less. However, it may also be the case that lightweighting a machine tool increases its complexity, which will likely drive up the cost to manufacture the machine. To explore the cost drivers associated with building a machine tool, data on the features associated with a wide variety of vertical milling machine tools are collected. Then, empirical cost models are fit to this data. The results from the cost models show that the machine tool mass is a significant cost driver; other key drivers are the number of axes and spindle power. The models are used to predict the cost benefits of lightweighting in terms of mass, which are compared to potential increased manufacturing costs associated with complexities introduced due to lightweighting.

In order to reduce the negative effect of lightweighting of suspension components on vehicle dynamic performance, the control arm and torsion beam widely used in front and rear suspensions were taken as research objects for studying the lightweight design method of suspension components. Mesh morphing technology was employed to define design variables. Meanwhile, the rigid–flexible coupling vehicle model with flexible control arm and torsion beam was built for vehicle dynamic simulations. The total weight of control arm and torsion beam was taken as optimization objective, as well as ride comfort and handling stability performance indexes. In addition, the fatigue life, stiffness, and modal frequency of control arm and torsion beam were taken as the constraints. Then, Kriging model and NSGA-II were adopted to perform the multi-objective optimization of control arm and torsion beam for determining the lightweight scheme. By comparing the optimized and original design, it indicates that the weight of the optimized control arm and torsion beam are reduced 0.505 kg and 1.189 kg, respectively, while structural performance and vehicle performance satisfy the design requirement. The proposed multi-objective optimization method achieves a remarkable mass reduction, and proves to be feasible and effective for lightweight design of suspension components.

In this paper, an evaluation of the static and dynamic behavior of bimetallic spur gears with different gear parameters is performed numerically. Bimetallic lightweight spur gears working without a decrease in the performance of the gear mechanisms have many potential benefits in automotive and aerospace applications. A bimetallic spur gear consists of two metals which are steel on the gear teeth and aluminum on the hub region. The dynamic performance of these gears is evaluated by using a two degree of freedom (2-DOF) dynamic model. The finite element method is used to calculate maximum root stress for varying ring thicknesses and other gear parameters for gears with symmetric and asymmetric teeth. These stress values and the weight reduction ratios are taken into consideration to optimize the ring thickness. Tooth deflection is also calculated to determine tooth stiffness by finite element analysis (FEA). Dynamic simulations are carried out to investigate the effects of gear parameters on the dynamic force and static transmission error (STE). Sample simulation results are illustrated with numerical examples. The results indicate that, if properly designed, bimetallic gears can provide a high potential to reduce the weight in power transmission systems without adverse effects on stress and dynamic behavior. (C) 2019 Elsevier Ltd. All rights reserved.

Lightweighting is one of the key solutions to reduce the carbon footprint of vehicles. Nowadays, it is still challenging to achieve this target because there is a conflict between the cost and final material performance, as well as the fact that many lightweight solutions are restricted to laboratory or small-scale production. In this work, a commercially feasible strategy was adopted to fabricate materials for lightweight applications. Hollow glass bubbles, jute fibres, and rubber powder were used as fillers with polypropylene as the base polymer. Various samples were fabricated using conventional and MuCell&reg, injection moulding. Their performance was then characterised by their density and morphological, mechanical, and rheological properties. A comparison among hybrid fillers/polypropylene compounds with and without MuCell&reg, technology was investigated. The filler hybridisation resulted in not only a density reduction of up to approximately 10%, but also improved tensile/flexural modulus and strength. The use of MuCell&reg, led to a further reduction in density of roughly 10%. Meanwhile, although some compounds fabricated by MuCell&reg, exhibited some deterioration in their tensile yield strength, tensile modulus, and impact strength, they maintained acceptable mechanical properties for automotive applications.

Carbon fibre (CF) recycling has been demonstrated to achieve reductions in environmental impacts compared to virgin CF production, but there is limited understanding of the financial viability of recycling and reutilisation of recycled CF (rCF). In this work, cost analysis and identification of market opportunities for rCF are performed by evaluating the cost of recycling, composite manufacture, and applications in automotive industry. Cost impacts of using rCF as a substitute for conventional materials and competitor lightweight materials are assessed over the full life cycle, including in-use implications. Recovery of CF can be achieved at $5/kg and less across a wide range of process parameters, approximately 15% of the cost of producing virgin carbon fibre. The life cycle cost results show that rCF composites, especially aligned rCF composites, give substantial cost reductions relative to virgin CF composites and even steel and aluminium.

The paper proposes a method aimed to support Life Cycle Assessment (LCA) in the evaluation of environmental benefits achievable by lightweight design solutions in the automotive field. The study is based on an in-depth calculation of car weight-induced Fuel Consumption (FC) resulting in the Fuel Reduction Value (FRV) coefficient; this is functional in modelling the use stage in a LCA perspective. The research is focused on Gasoline Turbocharged (GT) cars, since to date there is no systematic analysis of weight-induced FC reduction regarding this propulsion technology. The FRV is evaluated for a wide range of vehicle case studies representative of different classes within the 2015 European market. The assessment is performed concentrating on four standardized driving cycles in order to evaluate various driving styles both in the case of primary mass reduction only and in the case of secondary effect (powertrain adaptation in order to maintain vehicle's performance). For the vehicle case studies under consideration, FRV is within the range 0.159–0.237 and 0.252–0.477 l/100 km*100 kg respectively for mass reduction only and secondary effect. Starting from the data obtained, a criterion is refined for estimating the FRV coefficient based on car technical features. Such a method allows to estimate FC reduction precisely by means of the value of FRV closest to the specific application, and it is proposed as a valuable tool for LCA practitioners within the automotive lightweight context.

The existing Community regulation pushes the carmakers to design eco-sustainability of the vehicle over its life cycle to limit the consequences of the current state and the expected growth of the sector. In this sense, one of the primary aim is reducing raw materials consumption and emissions through the adoption of innovative materials and technologies. This implies the need for the carmakers to integrate Design for Environment (DfE) principles at the early Research and Development (R&D) stage. The article presents a concreate example of integration of DfE and LCA methodology application in the R&D process of a vehicle component produced by Magneti Marelli. The study allowed drawing a balance between the advantages of a lightweight solution with respect to the standard one both from performance and environmental point of view.

cited By 21; International audience; The current aim in the development of third-generation steels for lightweighting automotive applications is to increase strength keeping at least the same formability as current steel concepts. In this philosophy, an optimal concept would be one that brings, in addition, a lower density. For this purpose, low-density steels have been designed with important aluminum additions obtaining density reductions of 8–10% or higher in comparison with low-carbon steels. At the levels required for lightweighting, aluminum introduces complex phenomena in steels. Here, some of the effects of aluminum in phase stability, CALPHAD-type modeling, and microstructure development are described, the latter in relation with mechanical properties. Finally, the potential of two families of lightweight steels for automotive applications is assessed by comparison with a steel currently present in automotive structures. © 2014, The Minerals, Metals & Materials Society.

By identifying energy waste streams in vehicles fuel consumption and introducing the concept of lean driving systems, a technological gap for reducing fuel consumption was identified. This paper proposes a solution to overcome this gap, through a modular vehicle architecture aligned with driving patterns. It does not address detailed technological solutions; instead it models the potential effects in fuel consumption through a modular concept of a vehicle and quantifies their dependence on vehicle design parameters (manifesting as the vehicle mass) and user behavior parameters (driving patterns manifesting as the use of a modular car in lighter and heavier mode, in urban and highway cycles). Modularity has been functionally applied in automotive industry as manufacture and assembly management strategies; here it is thought as a product development strategy for flexibility in use, driven by environmental concerns and enabled by social behaviors. The authors argue this concept is a step forward in combining technological solutions and social behavior, of which eco-driving is a vivid example, and potentially evolutionary to a lean, more sustainable, driving culture., The authors acknowledge support from the Foundation for Science and Technology, Lisbon, Portugal, through the 3 degrees Quadro Comunitario de Apoio and the POCTI and FEDER programmes, and under the research Grants PEst-C/MAT/UI0144/2011 and SFRH/BD/33730/2009. Further thanks to the MIT-Portugal Program (www.mitportugal.org), and the COMPETE program from the European Regional Development Fund.