Tribological Performance of Materials Under Bio-Three Body Abrasion

Abstract

This study aims to investigate the effects of seed grinding process on the tribological characteristics of components in agricultural machines. The objective is to conduct the the effect of third body presence such as seeds on the tribological behavior of agriculture machines and evaluate the fracture mechanism of the seeds under three body abrasion loading conditions. The work consists of two main parts: Firstly, mechanical test which is related with the Hounsfield compression machines test and understanding the mechanical behaviour of wheat seed (Triticum aestivum) under compressive loading conditions. Secondly, the research aim to modify the current tribology machine to perform three body abrasion owing to test the rubbed components under seed third body configuration. Moreover, for each grind attempt, different discs have been used such as; the rubber disc, mild steel disc and stainless steel. The mechanical results revealed that the samples have maximum forces need to breakdown (rapture) the seed was (125 N) and minimum (84 N) average for all samples (102 N), stress results were maximum (1.81 Mpa), minimum (1.26 Mpa), average for all samples (1.58 Mpa) and in regarding to elongation average result was (0.86 mm). The failure mechanism was clear fracture in the seeds due to the brittleness behaviour of the seed and splitting of the seeds into two halves is the obvious damage feature. For the tribology machine, different attempts have been used to modify the machine to conduct the three-body abrasion for the grindings the seeds. However, there is no attempt displayed a good result. Grinding process for wheat seed by using rubber disc exhibited no result comes out because the seeds surfaces’ tribological properties cannot affect the rubber surface and both have the same smoothness surfaces. In another word, the seed shape is not multi-angles or has not brittle shape (nature) to provide better contact with rubber disc. Secondly with applying mild steel for grinding the same result find out the seed cannot grinding because the disc tribological still cannot supply best condition to crush seed might be this issue related with the shape of wheat seed also which is ellipse shape and the steel is highly smoothed. Therefore, both disc and seed are circle shape that is making them rotating each other’s rather than effect surface each other. Finally, the modification has been done for the tribo-machine enhancing the grinding operation. The modification was putting gear under the mild steel disc. This strategy helps the process quite successfully.