Research in Agricultural Engineering, 2005 (vol. 51), issue 2

Impact induced mechanical damage of Agria potato tubers

J. Blahovec

Res. Agr. Eng., 2005, 51(2):39-43 | DOI: 10.17221/4900-RAE  

Potato variety Agria was cultivated in different fertilisation and/or irrigation regimes. Tuber damage after impact was studied two months after the harvest with aim to find some relation between the regime of cultivation and impact test tuber damage. It was found that tuber cracking and/or crushing belongs to the most frequent mechanisms of damage masking usual bruising in many cases. Most severe tuber cracking was observed for cultivation with irrigation and classical methods of fertilisation. On the other hand, bruising was most frequent in case without any irrigation and fertilisation and in cases used for fertilisation the pig slurry. In every...

Grain aeration in hangar storage by low-pressure ventilators

P. Kroupa, J. Skalický, P. Kovaříček

Res. Agr. Eng., 2005, 51(2):44-49 | DOI: 10.17221/4901-RAE  

In the paper are presented measured values of air output velocity from the stored grain layer in hangar storage within its aeration by low-pressure ventilators. The proper aeration of the stored grain was conducted by three aerating ventilators of which every was individually connected with the "cage" aerating above-ground channel covered by technically woven fabrics. The channel diameter was 400 mm, axial pitch of the aerating channels was 4.5 m. Air output velocity was measured by the vane anemometer AIRFLOW. From the measured values resulted than the air output velocity from the stored grain layer in the hangar storage is insufficient, the used...

Loading regimes and designing helical coiled springs for safe fatigue life

M. Růžička, K. Doubrava

Res. Agr. Eng., 2005, 51(2):50-55 | DOI: 10.17221/4902-RAE  

Springs are loaded by harmonic forces very often. High cycles fatigue damage and failure can be found during its service loading. This paper shortly describes stress concentration factor for helical springs on the inner diameter of the spring wire and its evaluation by using FE Method. These results have been compared with correction functions published in the literature. The fatigue safety factor has been derived for three typical loading regimes of springs. All cases are demonstrated in the Haigh diagram. It has been showed that loading cases with constant operational prestress give lowest safety factor then the proportional or constant middle stress...

Draught requirements of enamel coated animal drawn mouldboard plough

I. A. Loukanov, J. Uziak, J. Michálek

Res. Agr. Eng., 2005, 51(2):56-62 | DOI: 10.17221/4903-RAE  

The power requirement of tillage implements is an important design consideration particularly for animal-drawn implements where the power is limited. The paper presents the possibility of reduction in the draught requirements of animal-drawn mouldboard plough by using enamel coating on the soil-engaged components such as the mouldboard, share and the landside. Trials were conducted to compare enamel-coated Maun Series single mouldboard plough (manufactured by Zimplow Limited, Bulawayo,Zimbabwe) with similar uncoated plough, both animal-drawn, under comparable working conditions. Experiments were done at 25% and 32% d.b. soil moisture content on a red...

Facilities of optimization of car parts in cad system pro/engineer

L. Ševčík

Res. Agr. Eng., 2005, 51(2):63-65 | DOI: 10.17221/4904-RAE  

New methods covered in this contribution describe the behavior of modeling algorithms that can be added to the parts and their assembly in the input data dependents. These input conditions could be of various types - dimensions, forces, moments, temperature and friction. The method includes the setting of requirements, combination of requirements, test of feasibility and test of sensibility. For consideration of user defined conditions of geometric and mass optimization can be made. Behavior modeling is a new programming product, which can stay as a part of CAD systems.

Mechanical characteristics of standard fuel briquettes on biomass basis

D. Plíštil, M. Brožek, J. Malaťák, A. Roy, P. Hutla

Res. Agr. Eng., 2005, 51(2):66-72 | DOI: 10.17221/4905-RAE  

The measuring has proved that the energy herbs can be pressed into the form of compact briquettes. It regards 9 varieties of the energy crops, i.e. coriander, crambe, saphlor, sorrel, sorghum, reed canary grass, knotweed, barley straw and rapeseed straw. These energy crops are disintegrated by the grinding mill ŠV 15 (manufacturer Stoza, Ltd.) before the pressing. The fraction size is given by the mesh size of circular cross section of diameter 15 mm. All the crops have constant moisture content during the measuring and uniform diameter 65 mm of the resulting briquettes. The biomass moisture ranges from 9 to 11%. The pressing is conducted by the briquette...