Influence of Geometry in the Behavior of Disc-Shaped Mechanical Energy Absorbers for Agricultural Tractors

Juan-Ignacio Latorre-Biel,José Ramón Alfaro-López,Amaya Pérez-Ezcurdia,Marta Benito-Amurrio

doi:10.3390/agronomy11122594

Juan-Ignacio Latorre-Biel, José Ramón Alfaro-López + Show 2 more

Open Access

https://doi.org/10.3390/agronomy11122594

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Journal: Agronomy	Publication Date: Dec 20, 2021
License type: CC BY 4.0

Affiliation: Universidad Publica de Navarra

Abstract

Disc-shaped mechanical energy absorbers (MEAs), in combination with rollover protection structures (ROPSs), may contribute to the prevention of the infringement of the safety zone and the collapse of the ROPS in case of the overturn of an agricultural tractor. An MEA can absorb a significant amount of potential energy of an overturning tractor and its deformation produces a rotation of the ROPS around the safety zone. In this research, MEAs with two different geometries have been developed. Both geometries present common features, such as disc dimensions, number of rings, and number of arms, but the distribution of the arms differs. Additionally, these MEA were manufactured in steel discs of four different thicknesses, ranging from 2 to 6 mm. The manufactured MEAs were tested in a universal testing machine, and their behavior characterized. From this data, linear models of the MEAs were developed. As a consequence, a number of characteristic parameters were selected and calculated, such as the activation load and the strain energy absorbed in a safe range of applied loads. Some patterns and trends were analyzed from the tested MEAs, which enables a better description of their behavior and the extrapolation of this behavior to other non-tested thicknesses and geometries.

Highlights

A rollover protection structure (ROPS) and the use of a safety belt is an effective combination to improve the chance of the survival of an occupant in an overturning tractor [1]
Linearized curves correspond to a simplified model of the mechanical energy absorbers (MEAs); it can be used in combination with analysis techniques, such as Finite Element Analysis (FEM), leading to much faster simulations than using more realistic models of the MEA
Characterization of the MEA behavior by the calculation of certain parameters eases the comparison of different MEAs and supports the decision of choosing the most appropriate MEA for a given application

Summary

Introduction

A rollover protection structure (ROPS) and the use of a safety belt is an effective combination to improve the chance of the survival of an occupant in an overturning tractor [1]. Significant efforts have been undertaken to introduce and improve safety systems in agricultural vehicles, where ROPS is a key component. The design of a ROPS, based on a parallelogram, and the consideration of rubber suspensions, were addressed by Gasparetto [5]. A ROPS and its attachments to the chassis of the vehicle should combine resistance and flexibility to effectively transform the potential energy of a vehicle into strain energy, in the event of overturn [6]. Some important parameters in the design of a ROPS, such as its dimensions, moment of inertia, mass, and center of gravity, were studied by Silleli et al [7]

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