2 research outputs found
GyĂĽmölcsfák csillapĂtási tulajdonságai rázáskor = Damping Properties of Fruit Trees at Shaking
A fa mint rezgĹ‘rendszer három fĹ‘ rĂ©szbĹ‘l tevĹ‘dik össze: a rezgĹ‘ talaj Ă©s gyökĂ©r, a törzs a vázágakkal, Ă©s a lombkorona. Mindegyik rĂ©sz kĂĽlönbözĹ‘ vesztesĂ©gekkel rendelkezik, ezeket kĂĽlön kell vizsgálni. Ismerve a csillapĂtást, az egyes rĂ©szek vesztesĂ©ge számolhatĂł az egyes rĂ©szek tömegĂ©nek figyelembevĂ©telĂ©vel. A törzs vesztesĂ©ge kicsi, ezĂ©rt a talaj Ă©s a lombkorona csillapĂtását elemeztĂĽk. A talaj csillapĂtását közvetlen energia mĂ©rĂ©ssel határoztuk meg az ĂĽzemi állapotnak megfelelĹ‘ ĂĽzemi körĂĽlmĂ©nyek között. Ezen feltĂ©telnek a stacionárius állapotot követĹ‘ kifutási diagramok feleltek meg. A diagramok feldolgozásához megfelelĹ‘ számĂtási mĂłdszert dolgoztunk ki. A kiĂ©rtĂ©kelĂ©s során a talaj logaritmikus dekrementuma 3,0 körĂĽl adĂłdott, sokkal nagyobbra, mint a korábbi kisamplitĂşdĂłjĂş mĂłdszereknĂ©l. A vázág Ă©s a lomb vesztesĂ©gĂ©t kĂĽlönbözĹ‘ mĂłdszerekkel vizsgáltuk. Ezek közĂĽl a statikus kitĂ©rĂtĂ©s mĂłdszere bizonyult a legmegbĂzhatĂłbbnak. A kezdeti kitĂ©rĂtĂ©s 10-20 mm volt, a kapott log. dekrementum 0,63 Ă©s 0,75 között mozgott, közĂ©pĂ©rtĂ©kben 0,69. Az fára vonatkozĂł számĂtott Ă©s mĂ©rt Ă©rtĂ©kek összehasonlĂtásábĂłl a legjobb közelĂtĂ©st a talajra Ă©s a lombra 3,0 illetve 0,68 Ă©rtĂ©kek adták, amelyek teljes összhangban vannak a mĂ©rt Ă©rtĂ©kkel. | A fruit tree, as a vibrating system, consists of three main parts: the vibrating root-soil mass, the trunk including the primary limbs and the tree canopy. All these parts have entirely different damping properties and each must be determined separately. Knowing the damping coefficients, the losses can be put together according to the participation by their masses in the entire system. Internal losses arising in the trunk may be neglected. It was decided to use a direct energy method to determine the logarithmic decrement of the soil. One possibility was the run-out test (deceleration test) of the tree-shaker system, during which the kinetic energy will be absorbed by the soil. The logarithmic decrement was determined using the decrease in kinetic energy cycle by cycle and an appropriate calculation method. The processing of experimental measurements gave logrithmic decrements values around 3,0. The damping capacity of the tree canopy (branches) was measured in several different ways. More reliable results were obtained using the static deflection method. The initial static deflections varied between 10 and 20 mm. This method was much more reproducible and primary limbs of different diameters showed nearly the same damping capacity. The results of some thirty measurements yielded logarithmic decrements between 0.63 and 0.75 with an average of 0.69