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United States Department of Agriculture

Agricultural Research Service

Research Project: Model and Field Data for Establishing New Grain Packing Factors

Location: Engineering and Wind Erosion Research Unit

2011 Annual Report


1a.Objectives (from AD-416)
The objective of this cooperative research is to obtain new field and laboratory data to refine and calibrate a science-based model for determining the packing of grains within upright storage structures. Laboratory data on bulk grain compression characteristics will be obtained for wheat, corn, soybeans, grain sorghum, oats, and barley. The refined model will be incorporated into a user-friendly software tool for use by producers, elevator operators, and government officials for predicting stored grain pack factors. Field measurements of grain packing will be obtained from several states in the southeastern U.S. in partnership with collaborators at ARS, Kansas State University, and the University of Kentucky who will also make field measurements. Field data will be collected primarily for wheat, corn, and soybeans and also for grain sorghum, oats, and barley when those crops are available.


1b.Approach (from AD-416)
This research is part of a larger, nationwide project to refine and validate a procedure with known accuracy, based on measurable physical parameters, for determining the packing of grains within upright storage structures. Because grain is somewhat compressible when subjected to the cumulative weight exerted from the material above, accurate packing factors are required to determine the mass of grain in storage from bin dimensions and test weights. Inventory control is critical for stored grain managers due to financial aspects (auditing by state agencies) and for the future utilization of quality management systems. The major variables affecting stored grain packing are grain type, moisture content, test weight, internal friction, and bin wall material, geometry, and dimensions. Variation across different regions of the U.S. must be investigated as well as other minor factors. A preliminary model for determining packing factors for a wide range of grains and bins is being developed that employs the differential form of Janssen’s equation to estimate the pressure and in-bin bulk density for a given depth of grain in a bin. In the larger project, this model will be calibrated and validated by measuring packing factors for selected grains in bins in all of the major grain producing regions of the U.S. As part of that nationwide effort, the Cooperator will measure packing factors in selected states in reasonable proximity to their locations. Improved estimates of the compressibility of grains as a function of overburden pressure will be obtained using a laboratory apparatus designed to simulate internal pressure from various depths of overbearing grain. Field measurements of packing factors will be obtained by measuring the height of grain in bins of known dimensions and wall materials as they are filled and/or discharged with a measured mass of grain.


3.Progress Report

A new user friendly, software version has been developed using the current data. This version runs in MS Excel 2007 for data input and also to display results. New, clear diagrams have been added to make the software more accessible by the grain industry. This improvement in the software interface is a major step forward from the previous MS DOS version. The new version is totally embedded inside an MS excel 2007 package, and is designed with three separate tabs (sheets) for “Information” (describes the software and packing theory), “Input values” (asks the user for input material and bin properties with the help of interactive diagrams), and “Output values” (provides the calculated values like % packing, volume of the grain, etc., along with re-displaying the input values). This new platform is easily modified to include new additions and further improvements of the input and output.

These activities were monitored via meetings and numerous conference calls and e-mail conversations with the cooperators to discuss project plans and review program goals and accomplishments.


Last Modified: 4/19/2014
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