P. Hrabě

Effect of Length of False Banana Fibre (Ensete ventricosum) on Mechanical Behaviour under Tensile Loading

Abstract The effect of gauge length of false banana fibre (Ensete ventricosum) on the tensile strength, volume energy, and modulus of elasticity under tensile loading was examined. Fibres of gauge length L0 (mm) 10, 20, 40, 80, 160, and 320 mm were prepared and tested until rupture point at strain rate of 0.05 min−1. Mathematical models describing the mechanical behaviour of the varying gauge lengths were presented. With the increasing gauge length of fibre, the tensile strength and volume energy decreased while the values of modulus of elasticity increased. The theoretical model describing the mechanical behaviour of Ensete fibre under tensile loading presented herein provides useful information for the fibres application in industry. The determined models could be used as a background for further research focused on Ensete fibre application.

Analysis of physical, mechanical and chemical properties of seeds and kernels of Jatropha curcas

Muller M., Hornickova S., Hrabě P., Mařik J. (2015): Analysis of physical, mechanical and chemical proper ties of seeds and kernels of curcas. Res. Agr. Eng., 61: 99–105. The research was performed to examine the physical, mechanical and chemical properties of seeds and kernels of Jatropha curcas. The test parameters were the dimensions of the seeds and kernels, required energy for oil ex traction , determination of fatty acids in the oil by gas chromatography method , determination of the iodine value , determination of the acid value, determination of total polyphenols by the Folin & Ciocault reagent and determina tion of tocopherols and tocotrienols (vitamin E) by High-performance liquid chromatography. It was ascertained that the size of the seed and kernel varies considerably . Pressing of whole seeds needs more energy (50%) than pressing of kernels. From a chemical point of view it seems to be very appropriate for a production of biofuels. Jatropha curcas contains more polyphenols and vitamin E, which act as antioxidants, than the rape . Due to the low content of unsaturated fatty acids it is chemically suitable to replace the rape-seed oil with Jatropha curcas oil.

Mechanical behaviour of selected bulk oilseeds under compression loading

Cold pressing or compressive mechanical expression of oil from bulk oilseeds without thermal treatments or appreciable thermal effects facilitates the preservation of quality in expressed oils and enhances their stability in storage. Mechanical response of bulk oilseeds during cold expression which are vital to equipment design vary with crops and are not completely understood. Mechanical behaviours of bulk seeds of camelina, pumpkin and sesame relevant to cold pressing were investigated at moisture contents of 7.04, 8.60 and 6.06% (d.b.), 80 mm pressing depth and a compressive force of 100 kN, applied uniformly at 10 mm min. Deformation varied with incremental force and among crops at peak compression. Deformations in Camelina, Sesame and Pumpkin seeds were 40.2, 41.6 and 50.9 mm at peak compression. Oil point pressures of Sesame, Camelina and Pumpkin seeds were 3.83, 7.49 and 8.83 MPa, respectively. Oil recovery at the applied load was similar in Camelina and Sesame but significantly lower in pumpkin seeds. Volume energy requirement for the expression of oil from camelina, pumpkin and sesame seeds were 2.56, 1.72 and 1.46 MJ m, respectively. An assessment of the pressed cake after oil expression revealed that the materials were capable of further deformation under compression.

Evaluation of techniques for ploughshare lifetime increase

Hrabě P., Muller M., Hadac V. (2015): Evaluation of techniques for ploughshare lifetime increase. Res. Agr. Eng., 61: 72–79. Sustainability in a sphere of agricultural commodities production depends on soil processing. The soil is also a considerable abrasive medium which affects in a negative way tools processing the soil. The aim of the research is to increase the lifetime of a mould board by means of a constructional setting of an overlaid material. The lifetime increasing of the ploughshare by means of the overlaying is a much discussed topic. For this reason such strategy for the experiment was chosen which would enable to increase the lifetime at preserving low costs for ploughshare treatment. The research was focused on the ploughshare lifetime increasing by means of overlaying the abrasive wear with resistant material. The ploughshares of one of the leading world producers of the soil processing machines were chosen for the experiment. The aim of the work is to compare two commonly available overlaid materials in the combination with two overlaying techniques.

Compacting Technologies of Polyethyleneterephtalate Bottle

The waste production is increasing owing to an economical development of the society. In the area of a communal sphere they are namely PET (polyethyleneterephtalate) bottles. The research aim was to evaluate methods of compacting the drinking PET packaging. The plastic drinking packaging waste is distinguished for its dominant representation. Owing to its construction it takes up a front place in low efficiency of a storing and transporting space comparing with a material yield. The efficient compacting of the drinking packaging leads to solving a problem with often fulled up containers. The volume decreasing by means of the compacting of the packaging waste can be done in a few ways. A basic sortion is a manual pressing without the press, second way is using the mechanical presses. A low efficiency of the packaging materials is one of essential problems from the sustainable progress of human society point of view. Statistical methods were used for evaluating results and deducing conclusions. The most often used PET drinking packaging (the volume 0.5 l, 1.5 l and 2.0 l) was evaluated. The volume of the bottle before compacting and after it was set on the base of a level uplift in a calibrated laboratory tub coming from the Archimedes´s law. Experiment results showed that an effective compacting rate was reached by a manual press

Dynamics of Treatment Device for Die Casting of Metals

The aforementioned proves that the grease flow in mould treatment equipment can be regarded as a regulation system with the input quantity by medium pressure p1 above the grease level and with the output quantity by the grease flow speed.The utilization of treatment equipment for die casting of metal enhances both the working environment and work culture during die casting of metals. Application of grease flow regulation results in better repeatability of die casting cycle which positively influences the quality of castings.