Stress relaxation of alfalfa under constant displacement
ABSTRACT Alfalfa is being used in the production of high density bales and wafers. The relaxation of the alfalfa under constant displacement is important for the determination of the optimum compression hold-time to minimize of the strength of retaining strapping for high-density bales. Experimental data was obtained and then analyzed using a three term exponential decay function. The functional dependence of the parameters on the moisture content, loading rate, maximum density, and leaf content was determined using stepwise linear regression on data from 140 tests. It was shown that the shortest time constants were most sensitive to moisture content, leaf content, and loading rate; whereas, the longest time constant was dependent on the moisture content and the maximum density used in loading the alfalfa. However, a hold time of less than 10 seconds reduces the stress level by approximately 60%.