Lightweight Vehicles Research Articles

Development of a Light-Weight Unmanned Aerial Vehicle for Precision Agriculture.

This paper describes the development of a modular unmanned aerial vehicle for the detection and eradication of weeds on farmland. Precision agriculture entails solving the problem of poor agricultural yield due to competition for nutrients by weeds and provides a faster approach to eliminating the problematic weeds using emerging technologies. This research has addressed the aforementioned problem. A quadcopter was built, and components were assembled with light-weight materials. The system consists of the electric motor, electronic speed controller, propellers, frame, lithium polymer (li-po) battery, flight controller, a global positioning system (GPS), and receiver. A sprayer module which consists of a relay, Raspberry Pi 3, spray pump, 12 V DC source, water hose, and the tank was built. It operated in such a way that when a weed is detected based on the deep learning algorithms deployed on the Raspberry Pi, general purpose input/output (GPIO) 17 or GPIO 18 (of the Raspberry Pi) were activated to supply 3.3 V, which turned on a DC relay to spray herbicides accordingly. The sprayer module was mounted on the quadcopter and from the test-running operation conducted, broadleaf and grass weeds were accurately detected and the spraying of herbicides according to the weed type occurred in less than a second.

Impact Resistance of Fibre Reinforced Composite Railway Freight Tank Wagons

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.

Experimental and numerical study of springback effect of advanced high strength steel in a V-shape bending

Advanced high strength (AHS) steel sheets are increasingly used for the production of various automotive structural parts. The components of new lightweight vehicles have very complex Shapes, for which more precise forming procedures are required in order to achieve a desired geometry. Hereby, springback occurrences of such AHS parts are often the most critical concern. In this work, it aimed to investigate springback effects of the AHS steel grade 980 in a V-shape bending process. Experimental bending test and its corresponding FE simulations were conducted. The Hill’48 and Barlat89 yield criteria, and the Yoshida-Uemori (Y-U) kinematic hardening model were applied. The yield function parameters were obtained from the tensile tests of samples in various orientations. The Y-U model parameters were determined from a cyclic tension-compression test and were afterwards calibrated with the 1-element simulation. The resulted bend angles measured from the experiment and predicted by FE simulations using the different models were compared and evaluated. For the bending in this work, the Hill’48 and Barlat89 models showed the predictive errors of springback angle 1% and 2% higher than the Y-U model, respectively. The accuracy of springback prediction could be improved by the Y-U model using C1 and C2 parameters around 1%. In addition, effects of sheet thickness and punch radius on the springback were afterwards studied and discussed by using the Y-U model.

A Brief Introduction of Dissimilar Welding Techniques forAluminum Alloys and Steel

The manufacture of lightweight vehicle bodies is an effective way to conserve energy and reduce harmful gas emissions. It is a very popular area of research with the growing problems of energy and environment

Crashworthiness optimisation and lightweight for front-end safety parts of automobile body using a hybrid optimisation method

This study proposes a hybrid optimisation method integrating contribution analysis, Entropy weight Technique for Ordering Preferences by Similarity to Ideal Solution (E-TOPSIS), design of experiments (DOEs), and grey relational analysis (GRA) for optimisation design of front-end safety parts of automobile bodies to improve the crashworthiness and lightweight of vehicles. First, the finite element model (FEM) of vehicle is established, and the simulation analysis and test of frontal collision for vehicle are performed. The key crashworthiness quotas of vehicle and the mass of safety parts are extracted as the optimisation responses. Second, the material, wall thickness and cross-sectional shape of the safety parts of the automobile body are taken as initial design variables. A variable screening method of contribution analysis combined with E-TOPSIS is proposed. The comprehensive contribution coefficient of numerous initial design variables to the crashworthiness and lightweight of vehicle is calculated using the proposed method, and the design variables are objectively screened by taking this coefficient as an evaluation index. Third, the DOE using Hammersley sampling is performed. Finally, the GRA method is proposed to analyse the experimental design results and obtained the optimal parameter combination of the material, wall thickness, and cross-sectional shape of the safety parts. After optimisation of the front-end safety parts of the automobile body, the crashworthiness safety performance of the vehicle is significantly improved and the mass of the safety parts is reduced by 11.02%. Therefore, the proposed hybrid optimisation method can effectively improve the crashworthiness and lightweight of vehicle.

Role of Direct Aging and Solution Treatment on Hardness, Microstructure and Residual Stress of the A357 (AlSi7Mg0.6) Alloy Produced by Powder Bed Fusion

Applying additive manufacturing (AM) technologies to the fabrication of aluminum automotive components, with an optimized design, may result in improved vehicle light weighting. However, the post-process heat treatment of such alloys has to be customized for the particular AM microstructure. The present study is aimed at investigating the effect of different heat treatments on the microstructure, hardness and residual stress of the A357 (AlSi7Mg0.6) heat-treatable alloy produced by laser-based powder bed fusion (LPBF, also known as selective laser melting). There are two major issues to be addressed: (1) relieving the internal residual stress resulting from the process and (2) strengthening the alloy with a customized heat treatment. Therefore, stress-relief annealing treatment, direct aging of the as-built alloy and a redesigned T6 treatment (consisting of a shortened high-temperature solution treatment followed by artificial aging) were examined. Comparable hardness values were reached in the LPBF alloy with optimized direct aging and T6 treatments, but complete relief of the residual stress was obtained only with T6. Microstructural analyses also suggested that, because of the supersaturated solid solution, different phenomena were involved in direct aging and T6 treatment.

Development of fast and hybrid charger for lithium ion batteries in light weight electric vehicles

This paper introduces a battery charging circuit, which utilizes solar and grid power for charging lightweight electric vehicles. The novelty of the proposed approach is the development of hybrid charger with control algorithm that charges the electric vehicle battery using dual input power. This hybrid charging provides electricity to start the electrically powered vehicle and also powers the additional vehicle. The controller can act as fast charger by closed loop operation with battery parameters as input. The speed of the charge level is varied based on the state of charge (SOC) of battery and parameters detected from battery side. Battery state estimation is defined through adopted battery model and their precision affects the accuracy of state estimation. Micro controller acts as a smart charger that controls the parameter of voltage and current level for battery charging. Battery output performance, voltage, and current variation in battery simulator during stage 1 to 2 charging level, current variation during stage 1 to 2 and stage 2 to 3 charging level by simulation and experimental results are also exhibited in the proposed work. Average power usage for conventional charger with proposed one during day and night time was compared. Time taken to reach 100% SOC for conventional charger with proposed system, probability of battery capacity, energy demand of charging station, effects of charging and discharging of battery, and charging capacity and temperature of battery is also further studied. The result analysis part proves that the proposed strategy shown to be superior to its existing methodologies.

Design, Manufacturing and Test of CFRP Front Hood Concepts for a Light-Weight Vehicle

Composite materials are very often used in the manufacture of lightweight parts in the automotive industry, manufacturing of cost-efficient elements implies proper technology combined with a structural optimization of the material structure. The paper presents the manufacturing process, experimental and numerical analyses of the mechanical behavior for two composite hoods with different design concepts and material layouts as body components of a small electric vehicle. The first model follows the black metal design and the second one is based on the composite design concept. Manufacturing steps and full details regarding the fabrication process are delivered in the paper. Static stiffness and strain values for lateral, longitudinal and torsional loading cases were investigated. The first composite hood is 254 times lighter than a similar steel hood and the second hood concept is 22% lighter than the first one. The improvement in terms of lateral stiffness for composite hoods about a similar steel hood is for the black metal design concept about 80% and 157% for the hood with a sandwich structure and modified backside frame. Transversal stiffness is few times higher for both composite hoods while the torsional stiffness has an increase of 62% compared to a similar steel hood.

Designing a Production-Ready Ultra-Lightweight Carbon Fiber Reinforced Thermoplastic Composites Door

<div class="section abstract"><div class="htmlview paragraph">Vehicle lightweighting has been a constant theme of research at numerous Original Equipment Manufacturers (OEM’s) as it provides one of the best opportunities for improving fuel efficiency. In this regard, the Department of Energy (DOE) Vehicle Technology Office set a challenge to lightweight a fully assembled driver’s side front door by at least 42.5% with the cost constraint of a maximum $5 increase for every pound saved. A baseline door of an OEM’s 2014 mid-size SUV was selected, and an integrated design, analysis, and optimization approach was implemented to meet this goal. The ultra-lightweight door design had to meet or exceed the fit & function and mechanical performance (static and dynamic) of the baseline door while being suitable for mass production. The design strategy involved parts consolidation, and multi-material distribution to enable mass reduction without compromising the fit and functional requirements. The primary structural component of this ultra-lightweight door design is a composite inner-frame made of a woven carbon/Nylon-6 composite material. While a finite element composite optimization technique was implemented to design the ultra-lightweight door that met the static and dynamic performance targets, it lacked manufacturing inputs. This study focuses on the feasibility of large-scale manufacturing of the composite inner-frame using thermoforming processes. One benefit of employing these processes is that the existing OEM stamping lines can be utilized with minor modifications with no additional capital cost for equipment. The scope of this paper is to identify the challenges in thermoforming of the thermoplastic door - including shear angle, tearing, and wrinkle formation - using draping simulation and share the solution in the form of countermeasures in the part design and tool concept to make the manufacturing of the final part feasible.</div></div>

Sustainability analysis of aluminium hot forming and quenching technology for lightweight vehicles manufacturing

The transport sector in the European Union contributes about one-fifth of the total CO 2 emissions, which is considered as the main greenhouse gas. Approximately 75% of these emissions originate from passenger vehicles. The environmental impact related to the use of vehicles depends on three main factors: the frequency of trips and distances, the mode of transport used, and the technologies used by each mode. A sustainable solution is attributed to the development of lightweight, low-cost vehicles, which will reduce fuel consumption and thus the CO 2 emissions levels. However, the production of lightweight vehicles is closely related to the replacement of steel from vehicle body structure with aluminium. The main objective of this study is to evaluate the environmental impact of the HFQ® technology process to manufacture high strength lightweight complex-shaped aluminium parts for the automotive sector by applying the methodology of Life Cycle Analysis. For the current analysis, the Functional Unit is a diesel vehicle with an average lifespan of 12 years and a total life mileage of 200,000 km for all life cycle phases (from primary aluminium, use phase and end-of-life treatment). It is indicated that the application of HFQ technology in diesel vehicle resulted in the reduction of the entire environmental impact (from “cradle” to “grave") by 17% and 7-7.5% in comparison to the baseline vehicle (conventional reference model) and the other forming technologies (aluminium casting, warm forming and hot stamping of steel), respectively.

High-Strength Poly(ethylene oxide) Composite Electrolyte Reinforced with Glass Fiber and Ceramic Electrolyte Simultaneously for Structural Energy Storage

The development of structural energy-storage materials is critical for the lightweighting and space utilization of electric vehicles and aircrafts. However, a structural electrolyte suitable for structural energy devices is rarely exploited. Here, a structural lithium battery composed of a fiber-reinforced structural electrolyte and a structural cathode is demonstrated. Benefitting from poly(ethylene oxide)–lithium bis(trifluoromethane)sulfonimide (PEO-LiTFSI) as the polymer electrolyte matrix and lithium aluminum titanium phosphate (LATP) and glass fiber (GF) as reinforcement fillers, the LATP-GF/PEO-LiTFSI composite electrolyte developed offers a high tensile strength of 33.1 MPa, large Li+ transfer number of 0.37, moderate ionic conductivity of 6.3 × 10–5 S cm–1 (at 25 °C), wide electrochemical window of 4.4 V, and high effectiveness in suppression of lithium dendrite growth. Finally, a structural lithium battery is demonstrated with acidified carbon fibers (ACFs) as the cathode, Li as the anode, and LATP-GF/PEO-LiTFSI as the electrolyte, which shows an ultrahigh tensile strength of 124.2 MPa and a moderate capacity of 1.45 mAh cm–2. Importantly, the ACF|LATP-GF/PEO-LiTFSI|Li cell can properly function under a high compressive stress of 11.26 MPa. It is believed that the design strategy with a fiber-reinforced polymer as the structural electrolyte and a carbon fiber woven fabric as the structural electrode is feasible to obtain high-performance structural energy-storage components.

Design of a Lightweight Multifunctional Composite Railway Axle Utilising Coaxial Skins

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.

Mechanically Efficient Cellular Materials Inspired by Cuttlebone.

Cellular materials with excellent mechanical efficiency are essential for aerospace structures, lightweight vehicles, and energy absorption. However, current synthetic cellular materials, such as lattice materials with a unit cell arranged in an ordered hierarchy, are still far behind many biological cellular materials in terms of both structural complexity and mechanical performance. Here, the complex porous structure and the mechanics of the cuttlebone are studied, which acts as a rigid buoyancy tank for cuttlefish to resist large hydrostatic pressure in the deep-sea environment. The cuttlebone structure, constructed like lamellar septa, separated by asymmetric, distorted S-shaped walls, exhibits superior strength and energy-absorption capability to the octet-truss lattice and conventional polymer and metal foams. Inspired by these findings, mechanically efficient cellular materials are designed and fabricated by 3D printing, which are greatly demanded for many applications including aerospace structures and tissue-engineering-scaffold. This study represents an effective approach for the design and engineering of high-performance cellular materials through bioinspired 3D printing.

An approach for the crash safety assessment of smaller and lightweight vehicles

Concerns around the externalities resulting from transport are leading to a reassessment of our mobility options. By reference to policy priorities, it is concluded that there will be an emerging demand for smaller and lighter vehicles. Within Europe these will be of the L6e and L7e category. However, the crash safety of these vehicles presents an impediment to their broader commercialisation, acceptance, and further development. The authors identify a number of concerns associated with the approaches to crash safety assessment being discussed and promoted by stakeholders. These concerns include: cascading down M1 category test requirements to the L6e and L7e category would be inefficient as there is little inclination at present to develop, manufacture and market small and lightweight M1 category vehicles; subjecting the L6e and L7e category vehicles to the same crash test and test performance requirements as an M1 category passenger car would not result in comparable performance in single vehicle or vehicle-to-vehicle collisions; and vehicle use cases will differ leading to different accident patterns and questioning the efficacy of the existing M1 category test approach for these smaller and lighter vehicles. To improve the safety of lightweight vehicles would require an innovative test and assessment framework that provides benefits to consumers, producers and society. As a contribution to this framework, an approach is proposed for the assessment of crashworthiness that: responds to the immediate concerns around the safety performance in frontal collisions; aligns with the emerging capabilities of the L-category industry; and provides the consumer with a new mobility option that responds positively to key externalities associated with our use and consumption of transport. The proposed assessment is discussed and is shown to provide equivalent compartment strength to a mid-sized M1 category passenger car – thereby addressing a key concern about compartment integrity in collisions with larger and heavier vehicles.

Life cycle energy and greenhouse gas emissions implications of using carbon fiber reinforced polymers in automotive components: Front subframe case study

Vehicle lightweighting benefits consumers through fuel savings, manufacturers through a more fuel-efficient vehicle portfolio, and the environment through reduced fossil fuel use and lower emissions. Vehicle components can be lightweighted by replacing conventional materials with alternatives such as aluminum or composites. However, lightweight materials come with their own set of environmental and economic challenges. Often, manufacturing of lightweight materials requires more energy than for conventional materials such as steel. Understanding the net energy and environmental benefits of lightweighting requires life cycle assessment with a large enough system boundary to prevent shifting of impacts and to ensure a fair comparison between different material options. Life cycle assessments of carbon fiber composite parts are hampered by substantial uncertainties in the energy needed for their production and recycling and the vehicle fuel consumption benefits. The present study addresses these deficiencies using a detailed vehicle fuel consumption model and industrially relevant carbon fiber production data and component design. The front subframe case study considered illustrates the challenges associated with achieving life cycle energy and greenhouse gas savings using carbon fiber. The base case with no powertrain resizing, secondary weight savings, or recycled carbon fiber and with 160,000 miles vehicle lifetime has no energy or emission benefits. When powertrain resizing, secondary weight savings, carbon fiber recycling, and increased vehicle lifetime travel were considered, energy and greenhouse gas benefits were found.

Reliability-based design for lightweight vehicle structures with uncertain manufacturing accuracy

Structural lightweight optimization is one of the key themes to continuously improve vehicle performance. However, most of the studies so far have not considered reliability and manufacturing issues brought about by the uncertainty of tolerances in structural lightweight optimization. In this study, a reliability-based design for lightweight vehicle structures with uncertain manufacturing accuracy is proposed. This method can provide not only the optimal design variables but also the maximum allowable deviation range. The main design variables lacking sample information are regarded as interval variables and other design parameters as probabilistic values. A progressive reliability-based design with uncertain manufacturing accuracy is established for lightweight vehicle structures by employing the transformation method of the interval model and the decoupling strategy of the probabilistic model. Firstly, the general test function is used to analyze the accuracy and efficiency of the reliability decoupling method. Then, lightweight optimization models of a classic cantilever beam and two vehicle structures (parking robot frame, energy absorption box) are established respectively, and the effectiveness of the present optimization method is verified. The optimized design results show that the optimal variables and the corresponding maximum allowable deviation range under acceptable manufacturing requirements can be obtained. The requirements for manufacturing accuracy can be reduced by appropriately increasing the deviation range of the design variables, which may lead to a reduction in manufacturing cost. This study aims to provide feasible design options by optimizing lightweight structures considering uncertain manufacturing accuracy.

Influence of Titanium Content on Thermal, Mechanical and Corrosion Behaviour Anomalies of Nickel-Molybdenum-Silicate Bulk Metallic Glasses

This work discussed the correlation between structural, mechanical, and corrosion studies variation on the milling time of (Ni75Mo15Si10)100-xTix (x = 0, 3, 6, and 9 at.%, labeled as Tix) BMG Powder system. Rietveld’s refinement analysis is used to analyze the full pattern matching of all the powder mixtures, which helped to obtain lattice parameters, average crystallite size, and micro-strain etc. The optimum substitution of titanium content about 6 at.% in the (Ni75Mo15Si10)100-xTix BMG network (Ti6 sample) exhibits the best glass-forming ability (GFA) relatively and reduced glass transition temperature (Trg), thermal stability, mechanical and corrosive resistant properties. The corrosion behaviour of all these samples is measured via electrochemical potentiodynamic polarization method. We also aim at how the Ti content affects Ni-Mo-Si BMG network’s corrosion resistance to be used as potential material for lightweight vehicle applications.

An Ultra-Efficient Lightweight Electric Vehicle—Power Demand Analysis to Enable Lightweight Construction

A detailed analysis of the power demand of an ultraefficient lightweight-battery electric vehicle is performed. The aim is to overcome the problem of lightweight electric vehicles that may have a relatively bad environmental impact if their power demand is not extremely reduced. In particular, electric vehicles have a higher environmental impact during the production phase, which should be balanced by a lower impact during the service life by means of a lightweight design. As an example of an ultraefficient electric vehicle, a prototype for the Shell Eco-marathon competition is considered. A “tank-to-wheel” multiphysics model (thermo-electro-mechanical) of the vehicle was developed in “Matlab-Simscape”. The model includes the battery, the DC motors, the motor controller and the vehicle drag forces. A preliminary model validation was performed by considering experimental data acquisitions completed during the 2019 Shell Eco-marathon European competition at the Brooklands Circuit (UK). Numerical simulations are employed to assess the sharing of the energy consumption among the main dissipation sources. From the analysis, we found that the main sources of mechanical dissipation (i.e., rolling resistance, gravitational/inertial force and aerodynamic drag) have the same role in the defining the power consumption of such kind of vehicles. Moreover, the effect of the main vehicle parameters (i.e., mass, aerodynamic coefficient and tire rolling resistance coefficient) on the energy consumption was analyzed through a sensitivity analysis. Results showed a linear correlation between the variation of the parameters and the power demand, with mass exhibiting the highest influence. The results of this study provide fundamental information to address critical decisions for designing new and more efficient lightweight vehicles, as they allow the designer to clearly identify which are the main parameters to keep under control during the design phase and which are the most promising areas of action.

Visualization of schistosomiasis snail habitats using light unmanned aerial vehicles

Schistosomiasis, or "snail fever", is a parasitic disease affecting over 200 million people worldwide. People become infected when exposed to water containing particular species of freshwater snails. Habitats for such snails can be mapped using lightweight, inexpensive and field-deployable consumer-grade Unmanned Aerial Vehicles (UAVs), also known as drones. Drones can obtain imagery in remote areas with poor satellite imagery. An unexpected outcome of using drones is public engagement. Whereas sampling snails exposes field technicians to infection risk and might disturb locals who are also using the water site, drones are novel and fun to watch, attracting crowds that can be educated about the infection risk.

Thermomechanical analysis on the frictional contact behavior of a high-strength steel 22MnB5–die steel H13 tribopair at 800 °C by experiment and finite-element simulation

High-strength boron steels are widely used in manufacturing the auto bodies and parts of light-weight vehicles, but the high rates of surface scratches and die wear have consistently occurred during hot stamping for these steels. For an in-depth understanding of the tribological characteristics at this interface, the frictional contact behavior and thermomechanical mechanisms of boron steel 22MnB5 against die steel H13 at 800 °C were studied through experiments and finite-element simulations. The coefficient of friction and worn surface topography were investigated by pin-on-disk sliding tests. A three-dimensional thermomechanical finite-element model of a friction pair was established to explore the interfacial dynamic variations. Experimental and simulation results show that severe elastic–plastic deformation occurred on the worn surface of the boron steel, whereas an increase in the load decreased the coefficient of friction within a certain range because the growth rate of shear force was slower than that of the normal force. When the finite-element model was changed from the gradual loading stage to the initial sliding stage, the tangential friction force further increased the plastic deformation on the surface of boron steel. The scratches and furrows were mainly caused by the compression and shear from asperities of the rough surface, as confirmed by the high-frictional-stress regions concentrated on the peaks and flanks of asperities. During the high-temperature and high-pressure experiments, the plasticized and softened surface materials of the boron steel adhered to the die surface readily, resulting in peeling and delamination.