Trends and Hybridization Factor for Heavy-Duty Working Vehicles

Reducing the environmental impact of ground vehicles is one of the most important issues in modern society. Construction and agricultural vehicles contribute to pollution due to their huge power trains, which consume a large amount of petrol and produce many exhaust emissions. In this study, several recently proposed hybrid electric architectures of heavy-duty working vehicles are presented and described. Producers have recently shown considerable attention to similar research, which, however, are still at the initial stages of development. In addition, despite having some similarities with the automotive field, the working machine sector has technical features that require specific studies and the development of specific solutions. In this work, the advantages and disadvantages of hybrid electric solutions are pointed out, focusing on the greater electromechanical complexity of the machines and their components. A specific hybridization factor for working vehicles is introduced, taking into account both the driving and the loading requirements in order to classify and compare the different hybrid solutions

Comparison Between Damping Coefficients of Measured Perforated Micromechanical Test Structures and Compact Models

Measured damping coefficients of six different perforated micromechanical test structures are compared with damping coefficients given by published compact models. The motion of the perforated plates is almost translational, the surface shape is rectangular, and the perforation is uniform validating the assumptions made for compact models. In the structures, the perforation ratio varies from 24% - 59%. The study of the structure shows that the compressibility and inertia do not contribute to the damping at the frequencies used (130kHz - 220kHz). The damping coefficients given by all four compact models underestimate the measured damping coefficient by approximately 20%. The reasons for this underestimation are discussed by studying the various flow components in the models.Comment: Submitted on behalf of EDA Publishing Association (http://irevues.inist.fr/handle/2042/16838

Mechanical Fatigue on Gold MEMS Devices: Experimental Results

The effect of mechanical fatigue on structural performances of gold devices is investigated. The pull-in voltage of special testing micro-systems is monitored during the cyclical load application. The mechanical collapse is identified as a dramatic loss of mechanical strength of the specimen. The fatigue limit is estimated through the stair-case method by means of the pull-in voltage measurements. Measurements are performed by means of the optical interferometric technique.Comment: Submitted on behalf of EDA Publishing Association (http://irevues.inist.fr/handle/2042/16838

Analysis of a Parallel Hybrid Electric Tractor for Agricultural Applications

The field of Non-Road Mobile Machineries (NRMM) is now more than ever considering the adoption of electric systems to reduce the amount of pollutant emissions per unit of work. However, the intensity and complexity of the tasks performed by a working machine during its life is an obstacle to the widespread adoption of electric systems. Specific design solutions are required to properly split the power output of the hybrid powertrain among the different loads (wheel, power take off, hydraulic tools, etc.). In this work, a performance analysis between a traditional agricultural tractor and a proposed hybrid electric architecture of the same vehicle is shown. The comparison was performed on a set of tasks characterized on a real orchard tractor which were used to build the input signals of two different numerical models: one for the traditional diesel architecture and the other for the hybrid electric solution. The two models were tested with the same operating tasks to have a one to one comparison of the two architectures. Peak power capabilities of the hybrid solution and performance of the Load Observer energy management strategy were investigated to validate the feasibility of the proposed solution

working cycle requirements for an electrified architecture of a vertical feed mixer vehicle

Abstract In the last years, the need for lower pollutant emissions has become one of the most discussed topic worldwide. Governments establish stricter regulations almost yearly in order to push the industry towards more efficient machines or, at least, lower harmful gas emissions. Agriculture is experiencing the same trend with strict regulations which force manufacturers to the massive use of diesel engine exhaust after-treatment systems. At the same time, industries are considering other options that can satisfy regulations and also add functionalities to their products. This research wants to show the results of the study which led to the first electric prototype of a self-propelled vertical feed mixer. A methodological approach in collaboration with an Italian feed mixer wagons manufacturer, allowed to characterize the traditional machine in all its working conditions leading to the necessary requirements for the design of the final electric architecture

Comparative Analysis of Hybrid Electric Architectures for Specialized Agricultural Tractors

In this work, a comparative numerical analysis between the performance of a conventional specialized orchard tractor and those of three different hybrid electric tractor configurations is presented. The aim was to compare several powertrain configurations in the same working scenarios derived from field measurements. Peak power capabilities and endurance were numerically tested with specific load scenarios involving both transportation mission profiles and field activities with external implements powered through the power take off of the tractor. The proposed hybrid architectures were configured with the same battery-based energy storage system to perform the comparison with the same energy storage capabilities. Two parallel, two series and one electro-hydraulic hybrid configuration were modeled and tested through simulations. The parallel ones excelled in peak power performance, whereas the series configurations had the highest fuel savings. The electro-hydraulic configuration was proposed as an alternative able to allow for a downsized engine but also for the introduction of the Continuously Variable Transmission (CVT) functionality, which is always an interesting feature for such working machines

Thermo magnetic {FEM} simulation of a {PM} synchronous motor with input data from telemetry driving cycles

Abstract Nowadays, the requirements to reduce greenhouse gas emissions and to provide a healthy and more habitable environment, has led to the development of several sustainable alternative for eco-mobility. Since the improvement of internal combustion engine has reached a steady state point in terms of overall efficiency, the increasingly stringent requirements imposed by international normative standards are leading automotive companies to find other alternatives to reduce pollution. Thanks to the exponentially growth of power electronics, the huge interest on research of high energy and power density batteries and the more integration of the embedded systems, the central role of the electric drive has taken over on most of vehicles applications. The wide use of permanent magnets synchronous motors for electric vehicles application has rapidly spread out, thanks to their capability to provide high torque and efficiency with low weight and size. Since the natural behaviour of permanent magnets to demagnetize under severe conditions, both coupled thermal and magnetics, the necessity to understand and predict the phenomena is mandatory. This paper carries out a performance analysis in duty cycle, given by real CAN and GPS readings in a studied pathway, with discussion of numerical and graphic technical evaluations. Finite element software has also been used for coupled electromagnetic and thermal calculation to set the magnets working point and establish the temperature distribution within the motor itself during the whole thermal transient. A particular overview is done on the dependence of material used and different cooling solutions adopted

Nordic walking multibody analysis and experimental identification

The widespread diffusion of Nordic walking as a trending sport discipline has increased the need for a tool to study the movement, both at the beginner and professional level. This article presents a methodology for the analysis of the body motion during Nordic walking. The main goal was to design a numerical tool able to replicate human body behaviour when performing this sport. With this approach, it is possible to study several biomechanical aspects, like the kinematics of each body segment, estimating loads applied to the joints for given tasks. Results can be used to compare the user movements with a standard technique implemented in the virtual environment. In fact, using a specific monitoring device developed in previous works, different parameters like the pole angle, arms cycle frequency and synchronization, as well as the pushing force applied to the ground, can be measured during the activity. This acquisition system can be used to save data to be compared with results from the standard numerical model, evaluating the user performance. In this work, numerical results were compared and discussed with measurements from the aforementioned device in terms of pole force and pole angle. The ground reaction force obtained with the multi-body model during Nordic walking was then compared with results from the literature

Shape Influence of Active Material Micro-Structure on Diffusion and Contact Stress in Lithium-Ion Batteries

Electrochemical-mechanical modelling is a key issue to estimate the damage of active material, as direct measurements cannot be performed due to the particles nanoscale. The aim of this paper is to overcome the common assumptions of spherical and standalone particle, proposing a general approach that considers a parametrized particle shape and studying its influence on the mechanical stresses which arise in active material particles during battery operation. The shape considered is a set of ellipsoids with variable aspect ratio (elongation), which aims to approximate real active material particles. Active material particle is divided in two domains: non-contact domain and contact domain, whether contact with neighbouring particles affects stress distribution or not. Non-contact areas are affected by diffusion stress, caused by lithium concentration gradient inside particles. Contact areas are affected simultaneously by diffusion stress and contact stress, caused by contact with neighbouring particles as a result of particle expansion due to lithium insertion. A finite element model is developed in Ansys™APDL to perform the multi-physics computation in non-spherical domain. The finite element model is validated in the spherical case by analytical models of diffusion and contact available for simple geometry. Then, the shape factor is derived to describe how particle shape affects mechanical stress in non-contact and contact domains

Analytical solution for coupled diffusion induced stress model for lithium-ion battery

Electric cycling is one of the major damage sources in lithium-ion batteries and extensive work has been produced to understand and to slow down this phenomenon. The damage is related to the insertion and extraction of lithium ions in the active material. These processes cause mechanical stresses which in turn generate crack propagation, material loss and pulverization of the active material. In this work, the principles of diffusion induced stress theory are applied to predict concentration and stress field in the active material particles. Coupled and uncoupled models are derived, depending on whether the effect of hydrostatic stress on concentration is considered or neglected. The analytical solution of the coupled model is proposed in this work, in addition to the analytical solution of the uncoupled model already described in the literature. The analytical solution is a faster and simpler way to deal with the problem which otherwise should be solved in a numerical way with finite difference method or a finite element model. The results of the coupled and uncoupled models for three different state of charge levels are compared assuming the physical parameters of anode and cathode active material. Finally, the effects of tensile and compressive stress are analysed