Browsing by Author "Tang, Zhong"

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    Development and validation of the damped pendulum model for cantilever conveyor trough using Lagrangian method
    (Transactions of the Chinese Society of Agricultural Engineering, 2023-12-25) Qian, Pengfei; Gu, Jiabao; Tang, Zhong; Lao, Liyun; Lu, Ting; Gu, Tingwei; Chen, Shuren
    Cantilever conveying trough has often caused the unbalanced swing in the rice combine harvester, leading to the high failure rate with the low operation efficiency. The purpose of this study is to establish a damped pendulum model for the cantilever conveyor trough of the combine harvester in the support of the hydraulic cylinder, in order to accurately analyze the unbalanced pendulum during operation. Taking the rice combine harvester as the research object, the force and dynamic models were established for the cantilever conveying trough using Lagrange equation. The hydraulic cylinder stiffness, damping and the total excitation were also determined in the damped pendulum model of the cantilever conveyor trough. Firstly, a static analysis of hydraulic cylinder was carried out using Workbench software. The hydraulic cylinder stiffness was solved to be 1.023 6×108 N/m. Then, the modal analysis was performed on the hydraulic cylinder, where the main vibration mode was corresponded to the intrinsic frequency of 60.604 Hz. The vibration acquisition test was also carried out, where the measurement points were set up at the front end and the rear end of the hydraulic cylinder. The hydraulic cylinder amplitude was obtained to integrate the acceleration signal. The logarithmic attenuation rate of amplitude was ln2. The intrinsic frequency and logarithmic attenuation rate of amplitude were then substituted into the damping formula to calculate the damping c of the hydraulic cylinder, which was 228.58 N·s/m. Finally, the half- and full-width field harvesting tests were implemented for the external excitation of conveyor trough. Four points were measured at the connection between the cutting platform and the conveyor trough. The acceleration signals were collected during the field tests. The quadratic integration and the Fast Fourier Transform (FFT) were utilized to obtain the amplitude of cantilevered conveyor trough and the main frequency components of vibration. The excitation characteristics of cantilever conveyor trough were obtained to verify the subsequent differential equations of dynamics. All parameters were verified in the damped pendulum model of the cantilever conveyor trough. The ODE45 function in MATLAB was used to solve the equations of angular velocity and pendulum angle of damped pendulum model. The amplitudes of pendulums were compared between the theoretical solution and field test at the measurement points 3 and 4 in the initial and steady state, indicating the excellent performance. It was found that the theoretically solved pendulum amplitudes of measurement points 3 and 4 were very close to the test under stable conditions, with the errors of about 1.11% and 4.30%, respectively. Therefore, the accuracy and feasibility of damped pendulum model can be expected to serve as the cantilever conveyor trough.
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    Rice stem lodging properties and bending modeling under the influence of circadian temperature difference
    (International Journal of Agricultural and Biological Engineering (IJABE), 2024-06-30) Wang, Bangzhui; Tang, Zhong; Lao, Liyun; Wang, Guoqiang; Jing, Tiantian; Yu, Yao
    Under diurnal temperature stress, the vascular bundle content of mature rice stems will change which will cause a change in the modulus of elasticity. Therefore, the rice stems will collapse with the reduction in bending resistance because of the change in the modulus of elasticity. In order to reveal the distribution of vascular bundle gradients in rice stems under different climatic temperatures and explore the locations where stems are prone to bending and the form of stem damage, this study established a model of stem stiffness under free loading based on observing microstructure of the rice. The lodging characteristics of rice stems was explored seldom in different environmental temperatures from a micro structure of rice stems. So, the statistical analysis and t-tests were carried out on stems 1 to 4 in combination for cantilever bending tests at room temperature on stem internodes 3, versus three-point bending tests at –10°C to 65°C temperature treatment. Results showed that the bending resistance of the stem can be well predicted by using the vascular bundle distribution regression model and the variable stiffness mechanical model. The bending resistance of No. 3 stem was established by using the results obtained from the three-point bending test in a temperature range between 10°C-65°C. The correction coefficient TF of stem bending resistance under temperature difference induced stress was established based on the Gauss regression model. Statistical analysis showed that the bending resistance of No.3 stem was relatively large in a temperature range of 16°C-34°C. This study elucidated the variations of the mechanical properties of rice stems under temperature difference induced stress and provided a theoretical foundation for understanding the lodging characteristics of rice during mechanized harvesting.