Analysis of Mechanical Properties of Whole Apple Using Finite Element Method Based on Three-Dimensional Real Geometry

Abstract

This study was intended to build 3D FEM geometry models of actual 'Fuji' apples by digitizing their surfaces, and to determine elastic modulus by FEM simulation based on the F-D curves of radial compression test from a point on apple equator. Also, the general protocol of ASAE S368.4 for predicting the apparent modulus of elasticity and the maximum contact stress for convex-shape food materials was evaluated for its appropriateness. The model apple for FEM analysis was composed of approximately 35,000 geometry elements that closely resemble the surface of an actual apple. Through FEM simulation, the average elastic modulus of 7.732 MPa was obtained at the loading condition of 0.5 BP, which was 8.3% smaller than the average apparent modulus of elasticity predicted by the ASAE standard. The maximum Von Mises stress at the points of initial contact with the compression target plates evaluated by FEM simulation was about 37% smaller than the maximum contact stress determined by the ASAE standard, and a poor correlation was found between the results of the two methods. These results could be explained by that a whole apple, in general, has an anisotropic structure with many complex and small curvatures, has fl esh texture bonded biologically, and is covered with more elastic membrane shell which contributes to prevent dehydration during compression.

Grasping damage analysis of apple by end‐effector in harvesting robot

“…In past, when researching finite element model of fruit, for the purpose of simplicity, many scholars assumed that the fruit was either a homogenous model constituted by pulp tissue only or a double deck mode constituted by skin and pulp tissue (Kim, Do, Bae, & Sagara, ). But in fact, just as shown in Figure , apple is constituted by skin, cortex, and core (Jafari & Nassiri, ).…”

Research on low damage apple picking end-effector

“…When analysing apples by finite element methods, most people assumed the apple fruit as a bilayer model consisting of only the pulp or only the skin and the pulp tissue for simplicity [23]. However, in reality, the apple fruit was mainly composed of three parts: the peel, the flesh, and the core (as shown in Figure 1(a).…”

“…The contact models of the flat finger and the three-point grip with the apple are shown in Figure 2. The first of these methods is a 2-point contact between the flat finger and the apple equatorial surface because the radius of curvature of the apple equatorial surface profile is smaller than the radius of curvature of the finger surface profile in both cases [23].…”

Research on Segmentation of Pear Shape from Unorganized Point Clouds

“…On the other hand, the mesh representation and image processing is still used for digitalization of real fruits [7] , even though there is a growing demand for more detailed and real models in agriculture. So in recent years, G. W. Kim [8] has begun to set about the actual apple model through finite element method (FEM) simulation, but it takes a long time to render highly detailed meshes with more artifacts. To overcome this drawback, new processing methods must be presented to preprocess, reconstruct and render these highly complex geometric bodies.…”