Marco Pierini

Design for disassembly: a methodology for identifying the optimal disassembly sequence

Optimizing the disassembly sequence of mechanical systems is very useful in order to improve maintenance and recycling activities (i.e. to reduce costs, times and number of operations). A new virtual disassembly environment, based on two different algorithms, is presented. The first analyses the physical constraints that oppose the movement of the mechanical element: starting from its three-dimensional computer-aided design representation, it creates the ‘AND/OR’ graph of a mechanical assembly that represents the space of disassembly solutions. The second algorithm, using a representation based upon binary trees, allows the automatic exploration of the set of all possible sequences. Among these, the optimal one can be identified, choosing a specific target function. The developed methodology provides the theoretical basis for the creation of a computer-aided design tool able to evaluate the ability to disassemble a mechanical complex during the early design phase.

On-field investigation and process modelling of end-of-life vehicles treatment in the context of Italian craft-type authorized treatment facilities.

The present article analyses the current situation of End-of-Life-of-Vehicles (ELVs) management in Europe, with particular attention on Italian condition. Similarly to other European countries, metal recycling is the main activity of the whole system, but such situation is evolving due to the 2000/53/EC Directive, which sets out targets for Reuse, Recycling and Recovery of ELVs. Due to the relevance of the ELVs problem, in 2008 Italian Ministry of Environment subscribed a framework agreement with competent stakeholders as carmakers, dismantlers, shredders. The main result is an industrial plan to promote (amongst other objectives) technological progress for residual waste (Automotive Shredder Residue-ASR) treatment. According with Italian Trial 2006 analysis about ELVs, Reuse and Recycling rate is currently estimated to be about 81%. At the present time, dismantling plants constitute the first collection points for ELVs; for this reason, during 2009 an investigation has been done over a number of ten Authorized Treatment Facilities (ATFs) operating in Italy. The first step of the analysis was aimed to find out major practices and methods through observations of ATFs activities and interviews to operators. Furthermore, the depollution and dismantling treatments of about 70 different ELVs have been observed and timed in detail over a period of three months. The results included the identification of most relevant critical issues in ELVs treatment, such as distortions between scrapping activities and Directives regulation, and the assessment of the time and of the resources needed to perform each operation. In the second step of the survey, a process simulation model has been built on the basis of such data. The model was aimed to include the real variability and all the uncertainties that are typical of dismantling activities; it is intended as a tool for process layout planning and for its management. Some control parameters have been introduced; these are able to dynamically modify process path depending on ELVs queues and priorities. The model can also be used for the economic assessments of single operations or of the whole treatment activity.

The influence of vehicle front-end design on pedestrian ground impact

Accident data have shown that in pedestrian accidents with high-fronted vehicles (SUVs and vans) the risk of pedestrian head injuries from the contact with the ground is higher than with low-fronted vehicles (passenger cars). However, the reasons for this remain poorly understood. This paper addresses this question using multibody modelling to investigate the influence of vehicle front height and shape in pedestrian accidents on the mechanism of impact with the ground and on head ground impact speed. To this end, a set of 648 pedestrian/vehicle crash simulations was carried out using the MADYMO multibody simulation software. Impacts were simulated with six vehicle types at three impact speeds (20, 30, 40km/h) and three pedestrian types (50th % male, 5th % female, and 6-year-old child) at six different initial stance configurations, stationary and walking at 1.4m/s. Six different ground impact mechanisms, distinguished from each other by the manner in which the pedestrian impacted the ground, were identified. These configurations have statistically distinct and considerably different distributions of head-ground impact speeds. Pedestrian initial stance configuration (gait and walking speed) introduced a high variability to the head-ground impact speed. Nonetheless, the head-ground impact speed varied significantly between the different ground impact mechanisms identified and the distribution of impact mechanisms was strongly associated with vehicle type. In general, impact mechanisms for adults resulting in a head-first contact with the ground were more severe with high fronted vehicles compared to low fronted vehicles, though there is a speed dependency to these findings. With high fronted vehicles (SUVs and vans) the pedestrian was mainly pushed forward and for children this resulted in high head ground contact speeds.

Decision logic of an active braking system for powered two wheelers

Powered two-wheeler (PTW) users are exposed to a high risk of accidents leading to severe injuries and fatalities. The trend of PTW accidents has pointed out the need for an intervention on PTW safety with new and effective solutions. One of the possible answers came from the EC-funded Powered two wheeler Integrated Safety (PISa) project which identified the autonomous braking of the vehicle as one of the most promising safety functions for PTWs. The aim of this paper is to report on the design of the decision logic for deploying a PTW autonomous braking system in case of an imminent collision. Rationales and limitations for this pioneering application are given. The feasibility of the autonomous deceleration is demonstrated by an experimental study conducted with the PISa test bike implementing a prototype of the autonomous braking system, named the Active Braking (AB) system.

Evaluation of an Autonomous Braking System in Real-World PTW Crashes

Objectives: Powered 2-wheelers (PTWs) are becoming increasingly popular in Europe. They have the ability to get around traffic queues, thus lowering fuel consumption and increasing mobility. The risk of rider injury in a traffic crash is however much higher than that associated with car users. The European project, Powered Two Wheeler Integrated Safety (PISa), identified an autonomous braking system (AB) as a priority to reduce the injury consequences of a PTW crash. The aim of this study was to assess the potential effectiveness of the AB system developed in PISa, taking into account the specific system characteristics that emerged during the design, development and testing phases. Methods: Fifty-eight PTW cases representing European crash configurations were examined, in which 43 percent of riders sustained a Maximum Abbreviated Injury Scale (MAIS) 2+ injury. Two of the most common crash types were a PTW impacting a stationary object (car following scenario) 16% and an object pulling across the PTW path (crossing scenario) 54%. An expert team analysed the in-depth material of the sample crashes and determined a posteriori to what extent the AB would have affected the crash. For those cases where the AB was evaluated as applicable, a further quantitative evaluation of the benefits was conducted by considering a set of different possible rider reactions in addition to that exhibited in the actual crash. Results: In 67 percent of cases, the application of AB could have mitigated the crash outcome. Analysis of those real crash cases showed the potential for an expert rider to avoid the collision. An early reaction of the rider, associated with a correct application of the brakes would have avoided 18 of the 37 car following/crossing scenarios. Conversely, according to the analysis, an expert rider would not have been able to avoid 19 of the 37 cases. In 14 of those 19 cases, the AB would have contributed to mitigating the crash outcome. Conclusions: This study demonstrated significant potential for application of the autonomous braking system in car following and crossing scenarios. In addition, the theoretical benefit curves for the AB globally, were able to provide good quantitative indications of its benefits in real cases where the AB was considered applicable. Further analysis with larger databases is suggested in order to confirm the magnitude of benefits in the PTW crash population. Supplemental materials are available for this article. Go to the publishers online edition of Traffic Injury Prevention to view the supplemental file.

Analysis of the minimum swerving distance for the development of a motorcycle autonomous braking system

In the recent years the autonomous emergency brake (AEB) was introduced in the automotive field to mitigate the injury severity in case of unavoidable collisions. A crucial element for the activation of the AEB is to establish when the obstacle is no longer avoidable by lateral evasive maneuvers (swerving). In the present paper a model to compute the minimum swerving distance needed by a powered two-wheeler (PTW) to avoid the collision against a fixed obstacle, named last-second swerving model (Lsw), is proposed. The effectiveness of the model was investigated by an experimental campaign involving 12 volunteers riding a scooter equipped with a prototype autonomous emergency braking, named motorcycle autonomous emergency braking system (MAEB). The tests showed the performance of the model in evasive trajectory computation for different riding styles and fixed obstacles.

Designing the Dynamic Behavior of an Engine Suspension System Through Genetic Algorithms

This work presents an innovative approach to dynamic design that has the significant advantage of allowing the dynamic requirements to be specified from the earliest design stage. The method applies genetic algorithms to optimize the dynamic behavior of the engine-subframe system and its links to the chassis. The optimization minimizes the sum of the amplitudes of the forces transmitted to the chassis from each mounting, while complying with the static and dynamic constraints. The genetic algorithm was applied to a multibody system model of the engine-subframe system and its links to derive new, improved configurations.

Further Development of Motorcycle Autonomous Emergency Braking (MAEB), What Can In-Depth Studies Tell Us? A Multinational Study

Objective: In 2006, Motorcycle Autonomous Emergency Braking (MAEB) was developed by a European Consortium (Powered Two Wheeler Integrated Safety, PISa) as a crash severity countermeasure for riders. This system can detect an obstacle through sensors in the front of the motorcycle and brakes automatically to achieve a 0.3 g deceleration if the collision is inevitable and the rider does not react. However, if the rider does brake, full braking force is applied automatically. Previous research into the potential benefits of MAEB has shown encouraging results. However, this was based on MAEB triggering algorithms designed for motorcycle crashes involving impacts with fixed objects and rear-end crashes. To estimate the full potential benefit of MAEB, there is a need to understand the full spectrum of motorcycle crashes and further develop triggering algorithms that apply to a wider spectrum of crash scenarios. Methods: In-depth crash data from 3 different countries were used: 80 hospital admittance cases collected during 2012–2013 within a 3-h driving range of Sydney, Australia, 40 crashes with Injury Severity Score (ISS) > 15 collected in the metropolitan area of Florence, Italy, during 2009–2012, and 92 fatal crashes that occurred in Sweden during 2008–2009. In the first step, the potential applicability of MAEB among the crashes was assessed using a decision tree method. To achieve this, a new triggering algorithm for MAEB was developed to address crossing scenarios as well as crashes involving stationary objects. In the second step, the potential benefit of MAEB across the applicable crashes was examined by using numerical computer simulations. Each crash was reconstructed twice—once with and once without MAEB deployed. Results: The principal finding is that using the new triggering algorithm, MAEB is seen to apply to a broad range of multivehicle motorcycle crashes. Crash mitigation was achieved through reductions in impact speed of up to approximately 10 percent, depending on the crash scenario and the initial vehicle pre-impact speeds. Conclusions: This research is the first attempt to evaluate MAEB with simulations on a broad range of crash scenarios using in-depth data. The results give further insights into the feasibility of MAEB in different speed ranges. It is clear then that MAEB is a promising technology that warrants further attention by researchers, manufacturers, and regulators.

Strategy-based approach to eco-design: an innovative methodology for systematic integration of ecologic/economic considerations into product development process

This paper shows how Rieter Automotive is approaching the integration of environmental considerations in product development process by providing an overview of all the involved elements playing a role in eco-design implementation, organised in a logical framework. A methodological approach is summarised, that integrates cultural aspects, product innovation issues and product strategic vision. The starting point for tool development is presented. Systematic integration of eco-design is proving to be feasible, but requires ad-hoc decision making and customised solutions, based on the company reality. The results of the project are showing promising opportunities for the improvement of the methods for optimised and eco-efficient design.

Determining the Loss Factor by the Power Input Method (PIM), Part 1: Numerical Investigation

Damping must be accurately determined in the design and/or optimization of vehicle and aircraft trim. Yet, owing to the complexity of the dynamic interaction among the components in trimmed panel systems, until now it has been difficult to obtain reliable damping estimates. In this work, the power input method (PIM), which compares dissipated energy to the structures strain energy, was evaluated as a damping evaluation tool. Numerical simulations were used to analyze the lumped mass system (with custom software) and the plates (with commercial finite element software) and consequently to evaluate the assumptions required to apply the PIM. It was thus possible to find a way of minimizing the effect of the assumptions on the results, whose importance would be fundamental in the successive phase involving the experimental application of the method.