Prediction of fruit cracking behavior in tomatoes due to irrigation using the extended finite element method

Fresh fruit rupture occurs in the process of fruit planting irrigation management, which seriously affects the postharvest quality of products along the supply chain. An extended finite element model was established to simulate the behavioral response of tomato exocarp cracking caused by changes in internal turgor pressure induced by irrigation. The whole tomato was modeled by using two parts: exocarp and pre-crack. A uniformly distributed pressure load based on amplitude curve was applied to the surface of the model locule to replace the change of internal turgor pressure during irrigation. The results showed that when the fruit was compressed and deformed to 5 %, the predicted initial internal turgor pressure was 0.22 MPa. Both the XFEM simulation and experimental data show that the minimum relative error between the XFEM simulation and the actual total crack length was 3.37 % when the peak of the internal turgor pressure was 3.5MPa. The model can simulate the deformation behavior and crack propagation of tomato pericarp after the change of turgor pressure caused by irrigation. In addition, the covariance analysis mathematical model showed that the factors affecting fruit cracking were pericarp thickness, internal peak turgor pressure, crack location, crack number, elastic modulus and failure stress. This study demonstrated the utility of XFEM as an explanation of pericarp crack behavior to understand the fruit cracking and crack propagation behavior of tomato under internal turgor pressure changes caused by irrigation, which has important implications for revealing the biomechanical mechanism of irrigation-induced crack in tomato.