A Critical Review of Optimization Methods for Road Vehicles Design

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/77078/1/AIAA-2006-6998-235.pd

A McPherson lightweight suspension arm

The paper deals with the design and manufacturing of a McPherson suspension arm made from short glass fiber reinforced polyamide (PA66). The design of the arm and the design of the molds have been made jointly. According to Industry 4.0 paradigms, a full digitalization of both the product and process has been performed. Since the mechanical behavior of the suspension arm strongly depends on constraints which are difficult to be modelled, a simpler structure with well-defined mechanical constraints has been developed. By means of such simple structure, the model for the behavior of the material has been validated. Since the suspension arm is a hybrid structure, the associated simple structure is hybrid as well, featuring a metal sheet with over-molded polymer. The issues referring to material flow, material to material contact, weld lines, fatigue strength, high and low temperature behavior, creep, dynamic strength have been investigated on the simple structure. The detailed understanding gained with the simple structure has been transferred on the actual suspension arm. The McPherson arm has been produced and withstood the technical specifications

Thermal Management of Electrified Vehicles—A Review

Vehicle electrification demands a deep analysis of the thermal problems in order to increase vehicle efficiency and battery life and performance. An efficient thermal management of an electrified vehicle has to involve every system of the vehicle. However, it is not sufficient to optimize the thermal behavior of each subsystem, but thermal management has to be considered at system level to optimize the global performance of the vehicle. The present paper provides an organic review of the current aspects of thermal management from a system engineering perspective. Starting from the definition of the requirements and targets of the thermal management system, each vehicle subsystem is analyzed and related to the whole system. In this framework, problems referring to modeling, simulation and optimization are considered and discussed. The current technological challenges and developments in thermal management are highlighted at vehicle and component levels

DRAFT: OBJECTIVE RIDE COMFORT MEASUREMENT

ABSTRACT The paper presents an innovative dummy conceived to provide an effective tool for an objective vehicle ride comfort evaluation. The first part of the research includes experimental tests on instrumented seats for evaluating the vertical (cushion) and longitudinal (backrest) acceleration between the vehicle seat and the seated human subject. Experiments have been performed by using a vibrating table fitted with a vehicle seat and by seating directly the subjects on vehicles (cars and light trucks) while running on a test track. The test track includes uneven road and different obstacles. Human subjects have been chosen in order to obtain a high variability in the anthropometric features (height, weight, gender, age). Several test have been also performed with the same subject submitted to the same excitation in order to investigate the inter-subject variability and the intra-subject variability. During the study different seats have been compared. From the acquired data, a mathematical model of the system, human subject + seat has been derived and numerically validated by minimizing the error between the measured and the computed accelerations. The corresponding mechanical device has been built, the MaRiCO dummy. The device is fully adjustable in order to simulate the vibrational behaviour of different human subjects. Particular attention has been devoted to the construction of the springs and of the magnetic damper to reduce as much as possible the friction between the moving components. The dummy rests on the seat by means of special elements that, thanks to their compliance and conformation, act as the tight and the back of human beings. An experimental validation of the dummy has been performed. The device, opportunely tuned and seated with the same posture of the corresponding human subject is able to reproduce the acceleration between the subject and both the cushion and the backrest.

Aerodynamic Effects on Ride Comfort and Road Holding of Automobiles

The effects of the aerodynamic actions an the body of automobiles running at high speed on randomly profiled roads are studied The forces acting m the body are introduced as functions of the air speed and some o f the state variables describing the vibrations m the vertical plane of the vehicle. The linearised analytical expressions of these forces assume a very interesting form: Sky-book springs and sky-hook dampers can be used to model the aerodynamic forces acting m the vertical plane an the vehicle body. Numerical simulations and experimental tests have been carried out to investigate the effects of aerodynamic forces an ride comfort and road holding of an automobile running at high speed m a randomly profiled road Both theoretical and measured data state that these effects appear to be sensible starting from vehicle speeds of 40–50 m/s. Suspension parameters should be tuned to account for aerodynamic effects which become more and more effective as the vehicle speed increases. Considerable improvement of ride comfort could be gained from a proper combined design of the suspension system and body shape

DRAFT: A DUMMY FOR REPRODUCING THE HUMAN WHOLE BODY VIBRATION

ABSTRACT The paper presents an innovative dummy conceived to provide an effective tool for an objective vehicle ride comfort evaluation. The first part of the research includes experimental tests on instrumented seats for evaluating the vertical (cushion) and longitudinal (backrest) acceleration between the vehicle seat and the seated human subject. Experiments have been performed by using a vibrating table fitted with a vehicle seat and by seating directly the subjects on vehicles (cars and light trucks) while running on a test track. The test track includes uneven road and different obstacles. Human subjects have been chosen in order to obtain a high variability in the anthropometric features (height, weight, gender, age). Several test have been also performed with the same subject submitted to the same excitation in order to investigate the inter-subject variability and the intra-subject variability. During the study different seats have been compared. From the acquired data, a mathematical model of the system, human subject + seat has been derived and numerically validated by minimizing the error between the measured and the computed accelerations. The corresponding mechanical device has been built, the MaRiCO dummy. The device is fully adjustable in order to simulate the vibrational behaviour of different human subjects. Particular attention has been devoted to the construction of the springs and of the magnetic damper to reduce as much as possible the friction between the moving components. The dummy rests on the seat by means of special elements that, thanks to their compliance and conformation, act as the tight and the back of human beings. An experimental validation of the dummy has been performed. The device, opportunely tuned and seated with the same posture of the corresponding human subject is able to reproduce the acceleration between the subject and both the cushion and the backrest

ANALYTICAL COMPUTATION OF THE RADIAL STIFFNESS OFPNEUMATIC TYRES

The paper presents a way to compute analytically the radial force and the radial stiffness of a generic pneumatic tyre. The aspect ratio, the inner pressure, the diameter, the hoop tension and other geometrical parameters are given. The theoretical analytical formula is validated by means of a number of experiments. A good agreement is found which enables a deeper understanding of the relationship between tyre data and tyre load carrying ability. Additionally, the presented theory allows simple analytical tyre models to be included in the future into control algorithm of actual cars

EXPERIMENTAL ASSESSMENT OF THE RIDE COMFORT OF FARM TRACTORS

The paper is focused on the assessment of the ride comfort of farm tractors. The problem of assessing the ride comfort is crucial due to the fact that operators spend part of their own lives on board of such machines, exposed to whole body vibrations potentially harmful for their health. The paper deals with the experimental measurement of the relevant vibration occurring at the tractor body, at the cabin and at the seat. The focus is on which accelerations are actually relevant and have to be taken into account. A number of farm tractors have been instrumented and run under monitored conditions. The test track was equipped with a number of cleats able to force at resonance the cabin and the seat. The six motions of the tractor body and the six motions of the cabin were measured. The motion of the seat was measured. The signals have been processed in the time domain. Some interesting occurrence have been highlighted referring to the amplification that a badly regulated seat can provide under certain circumstances. The comfort index was computed according with ISO 2631 and other standards. The acceleration of the seated subject was described at different positions on the body. It turned out that the acceleration of the head was particularly relevant for establishing a comparison among different tractors. Synthetic indices have been derived from the measured data able to correlate the subjective drivers' feeling with the measured level of vibration. The conclusion is that for a proper comparison of the ride performance of different farm tractors a huge number of measurements are needed. There is no possibility to record only the vertical accelerations to assess the ride co mfort of farm tractors