Compression-Induced Fracture of Maize Kernels: Effects of Moisture Content and Strain Rate on Mechanical Behavior

Abstract

During production processes, maize kernels are prone to mechanical damage from stresses such as collision and compression, leading to reduced storage stability, increased mold contamination risks, diminished processing performance, and consequent economic losses. Investigating the mechanical properties and fracture mechanisms of maize kernels is critical for reducing breakage and losses while safeguarding food security. This study systematically analyzed the effects of moisture content (9.75%, 13.07%, 16.66%, 20.67%, 25.21%) and compression speed (0.5, 2, 5, 50 mm/min) on anisotropic mechanical behavior through triaxial compression tests using a universal testing machine, integrating displacement–load curves, Dynamic Increase Factor (DIF), and Crash Force Efficiency (CFE). Results indicate that elevated moisture content significantly reduces mechanical strength, while increased compression speed partially counteracts moisture-induced softening via strain rate hardening effects. The minor axis exhibited the highest elastic modulus (891.78–1041.48 MPa) due to structural compactness, yet its DIF values (1.24–1.71) displayed pronounced sensitivity to moisture variations, reflecting greater operational condition dependency. The intermediate axis demonstrated superior energy absorption capacity, with CFE values (49.6%–64.2%) consistently exceeding those of the major axis (39.51%–53.79%). This research elucidates moisture-rate interaction patterns governing triaxial mechanical responses in maize kernels, providing theoretical foundations for optimizing the design and operational parameters of corn processing equipment.