3263

3172

كارشناسي ارشد

﴿ مكانيك ماشين هاي كشاورزي ﴾

اصفهان : دانشگاه صنعتي اصفهان ، دانشكده كشاورزي

1384

شانزده ، 88 ، [II] ، ص : مصور ، جدول ، نمودار

ص . ع :به فارسي و انگليسي

امين الله معصومي

عباس همت

مرتضي صادقي ، محمد شاهدي

مهندسي كشاورزي

ID3172

به فارسي و انگليسي : قابل رويت در نسخه دييجيتالي

Abstract To reduce storage space and transportation cost for alfalfa and straw bales wafering and recompressing of the bales are recommended For this purpose arecompressing device was designed fabricated and evaluated For optimum design some physical and rheological properties of the products are determined A confidecompression test for three level of axial strain 25 35 and 45 of initial length onalfalfa and straw bales using a factorial experiment in randomized complete blockdesign was performed The stress strain curve for each test was obtained and themodulus of elasticity and the energy for compressing were determined The highestvalue for the measured parameters were obtained for straw bales at 45 strain Pressure bulk density relationship using faborode model and elastic modulus bulkdensity relationship using sitkie and osobov models were obtained and thecoefficients of friction for alfalfa and straw bales on steel and galvanized surfaces atthree levels of normal loads using a factorial experiment in a randomized completeblock were determined Effect of bale and surface type on frictional coefficient wasnot significant P 0 05 however the effect of normal load was highly significant Tensile strength of hemp and nylon ropes which are usually used for knotting bales was measured Due to low strength of these ropes test was performed on knottingrope of plastic belt type The results shoed that these ropes had higher tensile strength Therefore the plastic belt type ropes were chosen for knotting the recompressed bales After fabrication of bale recompressing device the effect of three levels ofcompression 30 40 and 50 reducing in length on the increase in length ofrecompressed alfalfa and straw bales in relaxation chamber were measured by using afactorial experiment in a randomized complete block design with three replications The results showed that the recompressed alfalfa and straw bales with 50 reductionin initial length had the highest increase in length in relaxation chamber Therefore toreduce the length of the bales to recompress the alfalfa and straw bales by 55 and 60 in recompressing device to compensate for length recovery

امين الله معصومي

عباس همت

مرتضي صادقي ، محمد شاهدي