Harmonic stress analysis on Coffea arábica L. var. Colombia fruits in order to stimulate the selective detachment: A finite element analysis

Abstract

This study shows a finite element harmonic stress analysis to evaluate the stress performance at the pedicel interface of a fruit-peduncle system of Coffea arábica L. var. Colombia plants. The aim was to study detachment of fruits subjected to mechanical vibrations. A model of the coffee fruit-peduncle system is designed computationally to reproduce its topology in all ripening stages using a proposed numerical procedure. Young's modulus, Poisson ratio, and density were adjusted using analytical models for all ripening stages. The glomerulus of three fruits in different ripening stages was proposed and these were combined in four groups. Based on a detachment model, it was verified which fruit was detached first when a chirp force signal was applied on each glomerulus. Results indicated that dynamic excitations applied in between 130 to 150 Hz detached only ripe fruits, since fruits that were in other ripening stages were not stimulated until detachment in that bandwidth.

Effect of the impact of rigid rods on coffee fruit detachment efficiency by mechanical vibrations

“…This result can be attributed to the greater stiffness of the peduncles of the unripe fruits. Tinoco and Peña (2018) also observed a reduction on modulus of elasticity due the advance of the coffee ripening stage. According to Rodrigues and Ono (2001), the decrease in stiffness is related to the degradation of the peduncle cell walls by enzymatic activity.…”

“…Silva et al (2010) studied the coffee fruit detachment force and conclude that fruits in unripe maturation stage need greater forces to be harvested. This behavior may again be associated with the reduced stiffness of the peduncle in the ripe coffee samples (Coelho et al, 2015;Tinoco and Peña, 2018).…”

“…By subjecting the coffee plant to forced vibration, the response of this system becomes complex due to its geometric and mechanical properties. Therefore, factors such as vibration frequency and amplitude and ripening stage are important and necessary to understand the behavior of the system (Ciro, 2001;Oliveira et al, 2007;Santos et al, 2010a;Santos et al, 2010b;Silva et al, 2010;Tinoco et al, 2018;Coelho et al, 2015;Santos et al, 2015;Silva et al, 2015;Coelho et al 2016;Villibor et al, 2019).…”

Finite Element Analysis of Coffea arabica L. var. Colombia Fruits for Selective Detachment Using Forced Vibrations

“…Coffee fruit geometries were designed in SolidWorks ® software 2014 (Dassault Systèmes SolidWorks Corp., Waltham, MA, USA) applying the methodology described by Tinoco et al [15], which included using digital images for the geometric reconstruction of the fruit, as shown in Figure 2b. The fruit models are the same obtained in the study carried out by Tinoco et al [22]. Posteriorly, geometric models of the fruits will be used for harmonic finite element analysis.…”

Modeling and simulation of the dynamic behavior of the macaw palm fruit-rachilla system

“…[13][14][15][16][17][18][19] The use of computational modeling through numerical simulations is a skillful way of designing, understanding, and evaluating harvesting mechanisms without the need for destructive testing and the design of prototypes. [20][21][22][23] It is believed that the principle of mechanical vibration is applicable to the harvest of macaw palm fruits, 18 so the determination and knowledge of modal properties, natural frequencies, and modal forms of the plants, or part of them, are necessary when computationally studying the behavior and the interaction of the plant with the machines that can promote the harvest of its fruits. 21 The use of computational tools to obtain information about the dynamic behavior of physical systems allows lowcost and fast analyses in different scenarios.…”