Viscoelastic properties of seed cotton and their effect on module shape and density

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Title: Viscoelastic properties of seed cotton and their effect on module shape and density
Author: Hardin, Robert Glen
Abstract: Modules for cotton storage and transport should be constructed with a shape that will resist collecting water to maintain the quality of seed cotton during storage . Meeting this specification requires knowledge of the relationship between the applied compressive force , deformation , and time for seed cotton . Several factors were tested to determine their effects on the height and density of seed cotton during compression , creep loading , and recovery . Models were used to describe these processes . These results were used to develop an algorithm capable of providing information on module shape to the module builder operator . The initial loading density did not affect the compressed density , but a slight effect was observed in the recovered density , due to the weight of the seed cotton . Picker harvested cotton was compressed to a greater density than stripper harvested cotton , but expanded more during recovery , resulting in similar final densities . Multiple compressions increased the density , but this increase was not physically significant after the third compression . Higher moisture content increased the density seed cotton could be compressed to slightly . Viscoelastic behavior was observed ; however , the effect on density was small . Both the compression and creep curves were described using mathematical models . A compression model using an asymptotic true strain measure yielded high R2 values ; however , some aspect of this process remained unexplained and the equation was limited in its predictive ability . Creep behavior was described using a modified Burgers model . This model was more accurate than the creep model , although a definite trend existed in the creep model residuals . A feedback algorithm was developed based on the observation that the compressed density was primarily dependent on the mass of seed cotton and not the initial density . By measuring the compressed depth of cotton in a module and the hydraulic pressure of the tramper foot cylinder , the resulting shape of the module can be predicted . Improved loading of the module builder is necessary to produce a desirably shaped module . More seed cotton needs to be placed in the center of the module , resulting in a surface that slopes down towards the outer edges .
URI: http : / /hdl .handle .net /1969 .1 /1269
Date: 2004-11-15

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Viscoelastic properties of seed cotton and their effect on module shape and density. Available electronically from http : / /hdl .handle .net /1969 .1 /1269 .

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