Modelling rupture and relaxation characteristics of soybean under compressive loading

Abstract

This study evaluates the mechanical compression behaviour of soybeans varieties (P23A40E, XF31-32N, and EL30-33) for optimal energy usage in oil extraction. The influence of initial pressing height (20, 30, and 50 mm) and loading rate (20, 30, and 50 mm min⁻¹), and variety on rupture, deformation and relaxation behaviours were investigated. Compression tests were performed using a TestResources universal testing machine equipped with 5 kN and 25 kN load cells for single kernel and bulk soybeans, respectively. Mathematical models were used to characterize the load-deformation and relaxation properties of soybeans under compression. Results showed that variety, initial pressing height, and loading rate significantly affected rupture energy and modulus of elasticity (p < 0.05). Rupture energy increased while modulus of elasticity decreased with higher loading rates and initial pressing heights across varieties. The Tangent model (order 1–3) effectively described load-deformation characteristics, while the Peleg and Normand model provided an accessible method to model relaxation behaviour, presenting an RMSE <0.0058. The Maxwell Standard Linear Solid (SLS) model effectively simulated stress dynamics over compression and relaxation stages. Collectively, these models offer insights into load requirements, energy loss mitigation, and quality maintenance, with implications for scaling up compression-based soybean oil production. The study concludes that selecting optimal loading parameters based on variety-specific characteristics improves energy efficiency and oil yield. This comprehensive approach advances understanding of soybean behaviour under compression, enabling more efficient, quality-focused oil extraction processes.