The perpetual goals of agricultural machine design and development are optimizing the energy consumption, increasing the working quality and reducing the losses of machineries. One of the most efficient analysis methods for agricultural machinery designers is the time honoured in-situ test of the latest prototypes. However, due to the seasonal characteristic of agricultural processes and products these tests are limited in time, difficult to observe in detail and often proved to be very expensive. Numerical modelling of agricultural crops is becoming more common year by year. First, studies relating the mechanical behaviour of bulk crop assemblies were conducted by using the discrete element method (DEM). DEM is capable of modelling contacts and bonds among separate particles, making it an effective tool to analyse complex loading and breaking conditions of plant parts and to expand beyond the limitations of in-situ tests. Thus, researchers are turning to the modelling of fibrous agricultural materials (stalks and stems), however, due to its complex nature there is still no suitable simulation method and crop model that could predict the interactions among fibrous agricultural materials and machine parts. Maize (Zea mays L.) is one of the most cultivated crops of the world: almost 1050 million metric tons of maize were produced in 2017, while it also played an important role in Hungary's agricultural industry: 6.8 million metric tons were harvested in 2017. Based on the forecast of the Food and Agriculture Organization of the United Nations, approximately 1200 million metric tons will be harvested from almost 200 million hectares in 2050. The main parts of a maize plant are the root system, stalk, leaves, tassel, shank and maize ear. The stalk, the strongest part of maize plant, is constituted of nodes and internodes, both have the same skin-core (rind-pith) structure. Furthermore, there is a difference between the orientation of tissues in nodes and internodes as well: the orientation of the tissues is non-uniform while in internodes the tissues are oriented in longitudinal direction of the stalk. Accordingly, the biological structure of maize, especially the structure of the stalk, is suitable for our study. Consequently, maize has been chosen for the interest of the current study due to its importance in agriculture and its biological structure. The current project resolves to explore the suggestion that the DEM can be exploited to reproduce the mechanical behaviour and breakage of fibrous agricultural materials, such as maize plant. The primary objective of this thesis is to contribute to understanding of DEM modelling of fibrous agricultural materials and provide a model that represents the physical and mechanical existence of maize.
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