Dynamic study of cable lines transporting dragon fruit in the Southwest region

Comment :

Through the survey of regression functions, the parameters of horizontal tension H and cable span length for the cable curvature (f ) and oscillation amplitude (a) of the dragon fruit basket to reach the smallest value are: H = 5 kN and = 20 m. This is the largest value of horizontal tension H and the smallest value of considered in the experimental domain, these results are consistent with reality.

Chapter 4 Conclusion

From the experimental research results obtained, the thesis draws the following conclusions:

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1. An experimental research method has been developed to determine some dynamic parameters of cable lines, measuring equipment, measuring sensors, and experimental data processing methods have been selected.

2. Conducted experiments to determine cable tension, rotation and maximum oscillation amplitude of dragon fruit basket.

3. Conducted single-factor and multi-factor experimental studies, determined regression functions describing the dependence of the maximum rotation and oscillation amplitude of the dragon fruit basket when changing the cable tension and span length. The regression functions are all in the form of second-degree polynomials.

4. Verify the values of the cable's curvature and the oscillation amplitude of the dragon fruit basket depending on the horizontal tension H and the span length , calculated according to the experimental regression functions and the values calculated according to the theoretical formula. These values differ by about 10%. This proves that the theoretical calculation models are consistent with the reality and have reliability, that is, the assumption of inextensible wires and the load distributed horizontally instead of distributed along the cables is reasonable and acceptable.

5. Through multi-factor experimental research, the thesis determined a number of reasonable parameters of the dragon fruit transport cable line including: The most reasonable span length = 20 m and the most reasonable horizontal tension H = 5000N, galvanized steel cable type 6 strands 12 wires, cable diameter 6mm, then the rotation at the mid-span point is 21.5 cm and the maximum horizontal oscillation amplitude of the basket at the mid-span is 16.1 cm with the basket hanging wire r = 30 cm.

CONCLUSION AND RECOMMENDATIONS

1. Conclusion

Based on theoretical and experimental studies on the dynamics of dragon fruit transport cables, the thesis has achieved the following results:

1. By using research methods in the theory of flexible cable dynamics, the thesis has built a model, established a formula for calculating the cable's curvature (f), horizontal tension (H), cable length (L), reaction force on the supports (R) of the cable transporting dragon fruit in cases where the cable takes into account the stretch and does not take into account the stretch, the height of the two supports is equal and there is a difference in height. From this result, it is the basis for calculating the mechanical parameters of the cable, the dynamics of the baskets containing dragon fruit when moving on the cable system and also the basis for calculating the power consumption when operating the cable.

2. The thesis has built a dynamic model, established a system of differential equations of motion of the dragon fruit basket when moving on the cable span and at the cable redirection area. A survey of some parameters affecting the cable loop, oscillation amplitude and resonant frequency of the dragon fruit basket has been conducted. The survey results have determined the span length = 20 30m, horizontal tension H=3500 5000N, the resonance region f z =5.3  was determined6.5, proposed a solution to limit vibration and avoid resonance of dragon fruit baskets.

3. The thesis has established a formula for calculating power consumption when operating a cable line transporting dragon fruit, and has conducted a survey of the power consumption of the cable line. From the survey results, a reasonable electric motor capacity for the cable line of 236 - 315 W has been calculated. The above survey results are the basis for calculating the design of the power for the cable line transporting dragon fruit as well as transporting other agricultural products.

4. The thesis has built an experimental model to study the dynamics of the cable line transporting dragon fruit, has determined a number of parameters for the theoretical survey problem, by experimental research has determined the roundness (f), horizontal tension (H), oscillation amplitude of the dragon fruit basket (a). The experimental research results have been compared with the calculation results according to the theoretical model.

Theoretically, the error is within acceptable limits, so the theoretical calculation models are consistent with reality with high reliability.

5. Through multi-factor experimental research, the thesis determined a number of reasonable parameters of the dragon fruit transport cable line including: The most reasonable span length = 20 m and the most reasonable horizontal tension H = 5000N, galvanized cable type 6 strands 12 wires, cable diameter 6mm, then the rotation at the mid-span point is 21.5 cm and the maximum horizontal oscillation amplitude of the basket at the mid-span is 16.1 cm with the basket hanging wire r = 30 cm. The above reasonably determined parameters are the scientific basis for completing the dragon fruit transport cable line designed and manufactured by Vietnam.

2. Recommendations

Studying the dynamics of cable lines transporting dragon fruit is a big and complicated problem. Due to time constraints, the thesis has not had the opportunity to study some cases. To complete the topic, it is necessary to continue studying the following issues:

1. Calculate the mechanical parameters of the cable line in case the load is distributed concentratedly at many points on a multi-span closed double cable line.

2. Oscillation model of dragon fruit basket in case of uneven movement velocity of the basket, taking into account the external force of the worker acting on the basket when putting dragon fruit into the basket.

LIST OF PUBLISHED ARTICLES OF THE THESIS

1. Tran Van Tuong, Duong Van Tai, Nguyen Van Trung , Bui Le Cuong Quoc, Nguyen Huu Ich (2018), Principles of calculating cable lines for transporting dragon fruit , Rural Industry Magazine - No. 31, 2018, pages 9 ÷ 16.

2. Tran Van Tuong, Nguyen Van Trung (2018), Dynamic study of cable lines transporting dragon fruit, Journal of Rural Industry - No. 31, 2018, pp. 79 ÷ 83.

3. Nguyen Van Trung (2021), Building a dynamic model of a cable line transporting dragon fruit after harvest, Rural Industry Magazine - No. 42, 2021, pp. 9 ÷ 17

4. Nguyen Van Trung (2021), Dynamic survey of cable lines transporting dragon fruit after harvest, Rural Industry Magazine - No. 42, 2021, pp. 2 ÷ 8

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