Document Type


Journal/Book Title

Applied Engineering in Agriculture

Publication Date



American Society of Agricultural and Biological Engineers




Static and dynamic coefficients of friction on structural surfaces play important roles in the power requirements and material selection for equipment used in handling and storing agricultural commodities. However, friction data on dried distillers grains with solubles (DDGS) is limited. Further, lack of a standardized method for determining friction coefficient on grain handling materials presents a challenge. This article describes studies carried out to determine the static coefficient of friction (•_s) and dynamic coefficient of friction (•_d) for corn DDGS at 10%, 8.2%, and 6.5% moisture content (all moistures are % wet basis) on eight structural surfaces: High-Density Polyethylene (HDPE), Ultra-High Molecular Weight Polyethylene (UHMWPE), 20-gage aluminum, galvanized steel, mild steel, 18-gage stainless steel, poplar wood, and pine wood. For all structural surfaces and DDGS moistures tested, •_s lies in the range from 0.20 to 0.43 and •_d in the range from 0.17 to 0.35. The •_s values were higher than corresponding •_d values for all moisture levels. In general, •_s and •_d increased linearly with increasing moisture for metal and wood surfaces. Pine wood had the highest •_s at all moisture levels and the highest •_d at 8.2% and 10% moisture. HDPE had the lowest •_s and •_d at 10% moisture followed by the values for UHMWPE. For these surfaces the •_s and •_d remained the same or decreased with increasing DDGS moisture. Among the metal surfaces, galvanized steel and aluminum exhibited similar coefficient of friction characteristics however galvanized steel had the lowest •_s and •_d at 6.5% and 8.2% moisture.

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