Stress Relaxation Characteristics and Influencing Factors of Sweet Sorghum: Experimental Study

Abstract

Compression of biological materials facilitates their transport and storage. The compressive rheological properties of silage sweet sorghum were studied via stress relaxation test with an electronic creep universal testing machine and a self-made adjustable compression device. The moisture content, compression density, cutting length, and compression speed were analyzed. Relaxation characteristics of sweet sorghum stalk were evaluated in terms of the stress decay time and the equilibrium elastic modulus. The stress relaxation characteristics of sweet sorghum stalks were consistent with the two Maxwell models, and the relevant parameters of the model at different levels were obtained. The rapid stress decay time first increased and then decreased with the increase of compression density, and the length of the smashed sorghum. The moisture content and the compression speed had greater fluctuations. The equilibrium elastic modulus increased with increasing straw compression density and the length of the shredding segment, and the equilibrium elastic modulus gradually decreased with increasing moisture content. The compression speed had little effect on the equilibrium elastic modulus. The research results lay a theoretical foundation and a basis for further study on the stress relaxation characteristics of sweet sorghum.