Analysis of physical and mechanical properties of maize

AJAR: https://escipub.com/american-journal-of-agricultural-research/ 1 Huanxiao Pang et al., AJAR, 2022; 7:117 AJAR: https://escipub.com/american-journal-of-agricultural-research/ 2


Introduction
The physical characteristics of maize plant refer to the plant size and weight, ear height, ear big end diameter and ear stalk diameter of Maize in the harvest period. The height of maize plant is generally 1600 ~ 3000mm, and the ear setting height is generally 400 ~ 1200mm. The diameter of the big end of the ear is usually 40 ~ 65mm, while the diameter of the ear stalk is 9 ~ 19mm.
The more significant the difference between ear diameter and stem diameter is, the more conducive it is to ear picking [1] [2][3] [4] . When the diameter of the big spike is less than 40mm, the (temperature, medium and humidity) [5] [6] . The performance indexes include: elasticity index, hardness index, strength index, plasticity index, toughness index, fatigue performance, fracture strength, etc. The mechanical properties of maize refer to the resistance of Maize to external force and deformation, which is the inherent characteristics of maize [7] .

Physical properties of maize plant
In the harvest season of corn ear, the height and weight of straw, the height of ear, the diameter of straw and other parameters are called the physical properties of corn plant [8] .

Physical characteristic parameters of maize plant
GB / T 21962-2020 "corn harvester" in the detection of corn harvester in the provisions of the standard to determine indicators and methods [9] [10] .
Determination method: (1) For the characteristics of block planting, short length and narrow width in Hilly and mountainous areas, the test length is selected as 50m, in which the moisture content is guaranteed to be 25% ~ 35%, the plant lodging rate is less than 5%, and the ear drooping rate is less than 15%.
(2) Main measuring equipment and instruments: The above measured data were used for statistical analysis of physical parameters of maize plants. According to the data collected in Table 1, the following results are obtained: That is, reject domain: Where, c is the value of significant level, and By calculation，when α=0.05, n=40, c=0.3117 And, |r|=0.3119＞c Therefore, rejecting H0 proves that the diameter of the largest ear has a significant linear relationship with the diameter of the straw root.
The maximum ear diameter has a significant linear relationship with the straw root diameter, which provides a strong theoretical support for the design of gap adjustment components in the back ear picking mechanism. During the operation of the corn harvester, the purpose of the ear picking mechanism is to separate the corn ear from the corn straw. However, when the gap between the ear picking roller is too large, the ear picking roller and the corn straw cannot pull the stem effectively, so that the corn ear and the corn straw cannot be effectively separated; On the contrary, when the gap between the ear picking rollers is too small and the corn straw is pulled, the ears will also be squeezed and picked, resulting in ear grain loss and grain crushing.
Similarly, the correlation between straw root diameter and plant height is determined, and the data is entered into Excel for data analysis. The model output is

Mechanical properties of corn stalk
When the corn harvester is working, the ear picking mechanism will squeeze the corn straw, which will break the corn straw, especially at the stem node, so that the ear picking mechanism can not effectively pick the ears. Therefore, this part analyzes the extrusion characteristics of straw with knots [11] [12] .   Table 3 below. Then, the intercepted corn straw was numbered, the moisture content was measured, and the diameter was measured with vernier caliper [13] .
The determination of water content is mainly based on the determination method of wood moisture content in GB / T 1931-2009, and the intercepted corn straw is measured for the first time; Next, put the corn straw into the drying oven, take it out and weigh it every quarter of an hour, calculate the moisture content, and make the corn straw reach the range of moisture content to be measured.
The preliminary preparation work has been completed. Finally, the universal testing machine is used to carry out the extrusion test of corn straw [14] . The test mainly analyzes the moisture content, interception position and test speed of corn straw. This paper uses design expert to analyze and obtain the coding table shown in the following table.  Using design expert to analyze the above data, the preliminary analysis of variance is shown in the table below.

Mechanical properties of corn bracts
The purpose of analyzing the mechanical properties of corn bracts is to improve the stripping rate of corn ears by the stripping mechanism in the corn harvester [15] .
According to Zhao cheng shuai and others' Experimental Research on the mechanical properties of corn bracts, the interaction between the longitudinal tension, transverse tension and the number of layers of corn bracts is analyzed. The test data are shown in Figure 5 below.

Mechanical properties of maize grain
When harvesting the ear of corn, it will inevitably damage the corn grain, especially in the process of peeling. Therefore, in order to reduce the damage of harvesting machinery to corn grains and reduce the rate of grain loss, it is necessary to analyze the mechanical properties of corn    Corn crushing rate/% Impact times n of corn grains, which can better preserve the integrity of corn grains; However, when the impact speed is low, the corn grain breaking rate of the Striped rod is slightly better, which is mainly because when the corn grain is in the groove of the Striped rod, the groove will reduce the damage to this part.
During corn peeling, the corn ear loses the covering of bracts, making the corn grain directly contact with the peeling element, which is the main cause of corn grain damage. Therefore, the study on the damage degree of different types of impact elements to corn grains will help to carry out the design of corn peeling device in the later stage and minimize the damage of impact elements to corn ears.

Conclusion
This chapter mainly studies the physical and (2) The mechanical properties of grains are closely related to the moisture content. When the moisture content of grains is between, it is suitable to harvest ears. When the moisture content of grains is less than, it is suitable to harvest grains directly.