Experimental and numerical simulation research on damage characteristics and breakage behaviors of corn kernels

The current research performed uniaxial compression tests, single-kernel drop-weight impact tests, and multi-kernel rotary impact tests for semi-dent and flint corn kernels. The mechanical properties of corn kernels under monotonic compressive loading were examined across varying grain morphologies and moisture contents. The fracture modes, critical impact energies, and breakage evolution of corn kernels were studied. Finite element models of corn kernels were developed and validated. A breakage simulation method for corn kernels based on the extended finite element method (XFEM) was proposed, and the stress distribution characteristics and damage evolution behaviors of corn kernels were further investigated. The results indicate that both moisture content and kernel morphologies significantly affect the damage characteristics and breakage behavior of corn kernels. Kernels with low moisture exhibit typical brittle-material mechanical properties. As the moisture content of corn kernels increases, the kernels soften, and both the ultimate compressive strength and the uniaxial stiffness decrease. Flint kernels demonstrate better compressive performance compared with semi-dent kernels. Under the impact loading, with the increase of moisture content, the fracture mode shifts from brittle to plastic. The critical fracture energy and breakage energy of corn kernels first increase and then decrease, while the breakage ratio of semi-dent kernels first decreases and then increases; in contrast, that of flint kernels increases monotonically. Flint kernels possess higher critical fracture and breakage energies and exhibit a lower breakage ratio. The proposed XFEM-based numerical simulation approach can accurately describe the damage characteristics and breakage behavior of corn kernels.