Abstract
The search for alternative energy sources has fomented the study of several crops. The macauba palm crop, for instance, has been highlighted because of its particular relevance in Brazil due to its wide distribution across Brazilian territory and its potential for yielding high amounts of oil per cultivated hectare. However, the species is still most commonly harvested via extractivism, which results in low yields. Therefore, we aimed to analyze the dynamic behavior of the fruit-rachilla system when subjected to mechanical vibration to gather baseline information for the subsequent development of macauba harvesting machines. The fruit-rachilla system of the species was modeled for different fruit maturation stages and plant accessions. Natural frequencies and modes of vibration were determined by the stochastic finite element method (FEM), adopting the specific mass and the modulus of elasticity of the system as random variables, which enabled us to compile a dataset of natural frequencies based on the variability of the system properties. The mean values of the natural frequencies obtained in the vibration assays were 26.02 Hz at the green maturation stage and 21.22 Hz at the ripe maturation stage. The mean values of natural frequencies found in the simulation by stochastic FEM, referring to the third mode of vibration, were 26.05 Hz at the green maturation stage and 21.23 Hz at the ripe maturation stage. We concluded that the natural frequencies of the macauba fruit-rachilla system on the basis of different plant accessions showed a decreasing behavior during fruit maturation. The modes of vibration characterized by pendulum displacement did not differ among plant accessions or between fruit maturation stages.
Highlights
The search for new energy alternatives to meet the ever-increasing energy demand worldwide has been devoting considerable importance to research on biodiesel from several sources
The macauba palm [Acrocomia aculeata (Jacq.) Lodd. ex Mart.] is among the crops that have been the target of studies with such an aim, being the one crop with the highest potential for oil production per hectare (Lanes, Costa, & Motoike, 2014)
The species is still most commonly exploited in Brazil via extractivism, and harvest is largely performed through the direct cutting of bunches and manual extraction of fruits (Pires et al, 2013)
Summary
The search for new energy alternatives to meet the ever-increasing energy demand worldwide has been devoting considerable importance to research on biodiesel from several sources. To increase product quality and quantity of the macauba palm, production and harvest techniques of the species must be improved. Crop mechanization eases harvesting operations by the farmer and overall leads to lower fruit waste, thereby providing the producer with higher cultivation efficiency and rendering the cultivation process less damaging to fruits, improving the quality of the final product (Aguilera, Guzmán, Molina, Soto, & Infante-Amate, 2019). The mechanical vibration principle has been used in the mechanized harvest of several crops, such as orange, pistachio, coffee, olive, sweet cherry and grape (Pezzi & Caprara, 2009, Coelho, Santos, Pinto, & Queiroz, 2015, Zhou, He, Karkee, & Zhang, 2016, Yang et al, 2019). V. 43, e48565, 2021 natural frequencies, damping ratio, and modes of vibration) of the studied system must be previously known (Rao, 2011)
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call