IL CONFORT DEL POSTO DI LAVORO SULLE MACCHINE AGRICOLE: ESAME DELLE CRITICITA' E FORMULAZIONE DI SOLUZIONI.
Tesi di Dottorato
Data di Pubblicazione:
2012
Citazione:
IL CONFORT DEL POSTO DI LAVORO SULLE MACCHINE AGRICOLE: ESAME DELLE CRITICITA' E FORMULAZIONE DI SOLUZIONI / V. Bonalume ; tutor: D. Pessina. Università degli Studi di Milano, 2012 Jun 12. 24. ciclo, Anno Accademico 2010/2011. [10.13130/bonalume-valentina_phd2012-06-12].
Abstract:
Introduction.
The study of agricultural operator’s health must consider also the mechanical vibration risk. The continuous and various use of machinery through the year makes its exposure evaluation very difficult.
In particular, for the tractor drivers the risk is quite high: the vibration transmission to the body occurs primarily through the seat, depending the levels on several factors relevant to the machine structural characteristics and operative conditions.
On vehicles, Whole Body Vibrations (WBV) and Hand-Arm Vibration (HAV) are usually measured.
Vibrations are generally characterized through the following parameters:
- perceived axis: vibrations are very often multidirectional, but 3 axes are conventionally considered: vertical (z), longitudinal (x), transversal (y); if combined, they produce rotational vibrations;
- intensity, expressed in terms of acceleration (m/s²);
- frequency: the sensitivity of the human body along the 3 axes is a function of the frequency. At very low values (<2 Hz), the whole body reacts as a single and homogeneous mass; between 2 and 20 Hz the spinal column is more stressed and digestive and circulatory disorders may occur; at high frequency, from 20 to 1000 Hz the hand-arm district is particularly charged;
- exposure time: the limits specified by the Standards are generally referred to the 8 hr workday.
The exposure risk to mechanical vibration is essentially related to the individual sensitivity. As a consequence, the study of the exposure effects is very complex.
The relevant literature highlights a correlation between the exposure intensity and some specific diseases in the short, in the medium and in the long period:
- considering the hand-arm district, exposure causes vascular, neurological and muscular-skeletal problems;
- considering the whole body, the risk is related to diseases involving the spinal column; in particular, the range 2-10 Hz appears to be the most dangerous in the agricultural sector.
Materials and methods.
The Italian D.Lgs. 81/08 provides specific requirements for workers about the identification, evaluation and prevention of mechanical vibration exposure risks. Several vibration sources should be recognized in the agricultural activity; moreover, the variability of operative conditions makes the situation much more critical. In order to quantify the exposure level and evaluate the risk, the access to dedicated databases is allowed, but in this case the obtainable results are frequently very poor, because the values found show frequently a low accuracy in representing the real situation.
This enduring lack of data and of a standardized approach was highlighted also by the public institutions dealing with workers’health (INAIL, ASL, etc.), having them strongly requested the development of tools to solve the problem.
The goal of this research is the creation of a predictive model, in order to quantify the operator vibration exposure level on agricultural machinery, without measuring, nor instrumentally and systematically, the acceleration levels.
Taking into account the enormous variability of machines and operations carried out all over the year, the building of a unique general model, applicable to every agricultural chain is not logical. Therefore, the most suitable solution seems to be to develop many dedicated models.
The research was developed in different steps, all characterized by an experimental approach, both in the field and in laboratory. This led to an intense work of acquisition and analysis of the data, in order to create validated models, able to predict precisely the vibrational exposure levels considering the various operative conditions.
To acquire really comparable data, in the first part of the research a standa
Tipologia IRIS:
Tesi di dottorato
Keywords:
confort;macchine;agricole;lavoro;tractor;performance;sitribution;soil;compaction
Elenco autori:
V. Bonalume
Link alla scheda completa:
Link al Full Text: