Tractor accelerated test on test rig

The experimental tests performed to validate a tractor prototype before its production, need a substantial financial and time commitment. The tests could be reduced using accelerated tests able to reproduce on the structural part of the tractor, the same damage produced on the tractor during real life in a reduced time. These tests were usually performed reproducing a particular harsh condition a defined number of times, as for example using a bumpy road on track to carry out the test in any weather condition. Using these procedures the loads applied on the tractor structure are different with respect to those obtained during the real use, with the risk to apply loads hard to find in reality. Recently it has been demonstrated how, using the methodologies designed for cars, it is possible to also expedite the structural tests for tractors. In particular, automotive proving grounds were recently successfully used with tractors to perform accelerated structural tests able to reproduce the real use of the machine with an acceleration factor higher than that obtained with the traditional methods. However, the acceleration factor obtained with a tractor on proving grounds is in any case reduced due to the reduced speed of the tractors with respect to cars. In this context, the goal of the paper is to show the development of a methodology to perform an accelerated structural test on a medium power tractor using a 4 post test rig. In particular, several proving ground testing conditions have been performed to measure the loads on the tractor. The loads obtained were then edited to remove the not damaging portion of signals, and finally the loads obtained were reproduced in a 4 post test rig. The methodology proposed could be a valid alternative to the use of a proving ground to reproduce accelerated structural tests on tractors

FINITE ELEMENT ANALYSIS FOR THE PREDICTION OF THE CIRCUMFERENTIAL BAMBOO STRENGTH

Reported theoretical analyses have not explained the variation with radius of the circumferential strength of bamboo. This study aims to analyze this issue using finite element analysis. A rectangular image representative of the culm cross section of Phyllostachys edulis was divided along the radial direction into ten parts. Next, ten FE rectangular models representing the fibers, matrix, and void content at each radial position were generated. The matrix and the fibers were assumed to be isotropic, having elastic moduli of 1800 MPa and 18000 MPa, respectively. The strength predicted with the fiber first principal stress is parabolic along the radial direction, consistent with experimental findings

Thermal treatment of bamboo with flame: influence on the mechanical characteristics

The mechanical properties of bamboo are susceptible to degradation due to both physical and biological agents. Among the non-chemical treatments, we studied the influence of a short-time heat treatment, using an LPG-gas torch, on the mechanical properties of a bamboo (Phyllostachys viridiglaucescens) growing in Italy. The response was very encouraging as we found no significant reduction in either elastic modulus or tensile, compressive and bending strength. Several samples were subject to tension, compression and bending tests to compare the responses of the treated and untreated culms. The average tensile elastic modulus was slightly greater for the untreated culms. The average tensile strength of the untreated culms was only slightly greater, and the differences can be assumed to be insignificant from a structural point of view. The average value of the treated culms compressive elastic modulus was slightly greater than that of the untreated ones. The compressive strength was essentially the same. The bending mechanical behaviour was barely influenced by the thermal treatment. A microscopic investigation (optical and electron microscopy) was undertaken to investigate the possible deterioration of the bamboo microstructure due to the heat treatment. No appreciable damage was detectable in the treated material. The proposed heat treatments can be considered as a reliable and sustainable protection practice for bamboo culms

Theoretical and experimental study on mechanical characterisation of a water drop impact on a solid surface

The drop impact phenomenon can be used to study many agricultural aspects related to the rainfall, runoff and irrigation, such as the stability of aggregated and the detachment of fine particles. The aim of this study was to study experimentally and numerically the water drop impact on a solid wall. In a first phase a simple experimental apparatus and basic theoretical concepts were used to investigate the influence of the drop speed on the impact pressure. In the second section, a finite element model able to reproduce the complex phenomenon observed in the experimental phase, was developed. The pressure values obtained by experimental measurement are similar to those calculated on the base of the energy conservation principle (average percentage difference of 15.6%). Numerical model was useful to obtain important information on pressure profile inside the drop and the impact pressure during the splash, at present hard to achieve experimentally. The model was used to estimate also an almost realistic dynamic behaviour of the spreading drop

Simple and efficient approach for shelf-life test on frozen spinach and parsley

open6noA simple test for shelf-life assessment of frozen spinach and parsley is presented. A specific shelf-life test that considers three storage temperatures is proposed to accelerate the rate of quality decay in frozen spinach and parsley. The scope was to provide a reliable and rapid way (one month vs years) to predict shelf-life by using a simple experimental approach and mathematical models based on some physical quality product attributes. Physical properties were evaluated at three storage temperatures: -5 degrees C, -10 degrees C and -26 degrees C, to simulate a possible thermal abuse. Mechanical and thermal indexes were defined measuring maximum compression force (N) and latent heat involved in ice melting (J/g). A zeroorder kinetic model was used to properly fit experimental data and thus to obtain related reaction rates. The determination coefficient indicates that there is a strong linear relation between kinetic parameters at -10 degrees C or -5 degrees C and -26 degrees C. This suggests a reliable procedure for shelf-life estimation, carrying out a test at -10 degrees C or -5 degrees C for one month and extending values to data acquired at 26 degrees C for the same period of time. The relations obtained from this research have led to a simple practical approach: one day at -10 degrees C could be considered roughly equivalent to 30 days at -26 degrees C. Accordingly, it could be possible to obtain a shelf-life estimation in short time, also considering other similar products.openIaccheri, Eleonora; Cevoli, Chiara; Romani, Santina; Dalla Rosa, Marco; Molari, Giovanni; Fabbri, AngeloIaccheri, Eleonora; Cevoli, Chiara; Romani, Santina; Dalla Rosa, Marco; Molari, Giovanni; Fabbri, Angel