**1. Introduction**

The elastic characteristics of wheat constitute fundamental data for designing cleaning shakers and sowing plates in wheat harvesters. During the screening operation of the harvester cleaning system, wheat undergoes collisions and ejections, either with other wheat particles or with the screen body, within the screening bin. The efficacy of the cleaning system's screen selection is influenced by these collision and ejection motions. Furthermore, an array of collision and ejection movements occurs as wheat is transported within the seed harvester, seed scraper, and seed feeder during seeding operations. Consequently, studying the elastic characteristics of wheat bears considerable significance for enhancing the vibratory screening mechanisms of wheat cleaning and the functional components of wheat seeders.

The recovery coefficient represents the capacity of an object to recover from deformation during collisions, first introduced by Newton as he employed the instantaneous impulse method to resolve the collision issue of rigid body systems. This coefficient serves as an essential parameter for characterizing alterations in the motion state of objects preand post-collision. Currently, extensive research has been conducted on elastic collision theory, the exploration recovery coefficient, and the methodologies for measuring these coefficients both domestically and internationally. Ning et al. assessed the elastic recovery coefficient for two soybean varieties [1]. Liu et al. analyzed and calibrated the elastic recovery coefficient for wheat seeds via a wheat accumulation test, subsequently deriving

**Citation:** Wang, J.; Zhang, W.; Wang, F.; Liu, Y.; Zhao, B.; Fang, X. Experimental Analysis and Verification of the Influence on the Elastic Recovery Coefficient of Wheat. *Appl. Sci.* **2023**, *13*, 5481. https:// doi.org/10.3390/app13095481

Academic Editors: Li Pei, Jia Shi, Hua Bai, Yunhui Mei and Pingjuan Niu

Received: 12 March 2023 Revised: 31 March 2023 Accepted: 4 April 2023 Published: 28 April 2023

**Copyright:** © 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).

the discrete element parameters of wheat [2]. Li et al. measured maize seeds' recovery coefficient and established the contact parameters between maize seeds and seeders [3]. Kong investigated and analyzed the recovery coefficient for seed cotton; Yang et al. measured and analyzed the collision recovery coefficient for castor capsules [4]. Liu determined the collision recovery coefficient for oil sunflower grains [5]. Wen gauged the recovery coefficient of garlic seeds [6]. Zhang measured the recovery coefficient of mung beans [7].

In this study, Ji'nan 17 wheat seed was selected, and based on the analysis of the principle of kinematics, a wheat seed falling impact test platform was designed. The effects of the contact material, grain fall height, material thickness, and grain water content on the collision recovery coefficient of wheat were investigated through single-factor and multi-factor experiments, providing a basic data reference for the design optimization of harvesting and seeding machinery structure and the simulation modeling of loss sensor [8,9].
