This study derives load characteristics and analyzes the safety of plowshares operating in dry fields. We mounted a three-blade, reversible plow on a 23.7 kW tractor and measured the plow's tractive force as well as the torque from the engine output shaft on the rear axle under various working speed...
This study derives load characteristics and analyzes the safety of plowshares operating in dry fields. We mounted a three-blade, reversible plow on a 23.7 kW tractor and measured the plow's tractive force as well as the torque from the engine output shaft on the rear axle under various working speeds (L4, M1, M2, M3). We chose a Korean test site of Seomyeon, Chuncheon with sandy soil texture, as determined using the USDA method. We constructed the load spectrum for torque and tractive force using measured data and derived the fatigue life of the plowshare from a stress-cycle (S-N) curve of the plow material. Our results show that the M3 gear maximizes the driving shaft torque loads and, applying the tractive force load spectrum, creates a cumulative damage sum of $4.14{\times}10^{-5}$. Considering sampling time, we estimate a fatigue life of 805 hours while using the M3 gear. When using the other working speeds, however, all of the stress levels fell within the endurance limits and, therefore, our model predicts infinite plowshare lifetimes. For this analysis, we used a yield strength of 1,079 MPa for the plowshare and static safety factors, analyzed using the maximum stress, between 6.83 and 8.63 under each working speed.
This study derives load characteristics and analyzes the safety of plowshares operating in dry fields. We mounted a three-blade, reversible plow on a 23.7 kW tractor and measured the plow's tractive force as well as the torque from the engine output shaft on the rear axle under various working speeds (L4, M1, M2, M3). We chose a Korean test site of Seomyeon, Chuncheon with sandy soil texture, as determined using the USDA method. We constructed the load spectrum for torque and tractive force using measured data and derived the fatigue life of the plowshare from a stress-cycle (S-N) curve of the plow material. Our results show that the M3 gear maximizes the driving shaft torque loads and, applying the tractive force load spectrum, creates a cumulative damage sum of $4.14{\times}10^{-5}$. Considering sampling time, we estimate a fatigue life of 805 hours while using the M3 gear. When using the other working speeds, however, all of the stress levels fell within the endurance limits and, therefore, our model predicts infinite plowshare lifetimes. For this analysis, we used a yield strength of 1,079 MPa for the plowshare and static safety factors, analyzed using the maximum stress, between 6.83 and 8.63 under each working speed.
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가설 설정
0. In this study, stress spectrum was derived from the load spectrum of equivalent completely reversed load. And partial damage was calculated by the ratio of actual number of cycles at each stress and the number of cycles corresponding to the stress in the S-N curve.
제안 방법
The load spectrum was analyzed by measuring the tractive force of the plow, and the torque of engine output shaft and rear axle. Based on this, fatigue life of the plowshare was predicted, and safety analysis was performed.
In order to construct the load spectrum of the plow operation, measuring system was composed to measure the engine output shaft torque, the rear axle torque, and the tractive force of plow. Figures 3 and 4 show the overall configuration of a measuring system mounted on a tractor.
The construction of the load characteristics database about the plow operation requires load measurements at various soil conditions and working conditions. In this study, loads of the plow operation were measured under various working speed in dry field. The load spectrum was analyzed by measuring the tractive force of the plow, and the torque of engine output shaft and rear axle.
In this study, loads of the plow operation were measured under various working speed in dry field. The load spectrum was analyzed by measuring the tractive force of the plow, and the torque of engine output shaft and rear axle. Based on this, fatigue life of the plowshare was predicted, and safety analysis was performed.
This study analyzed the tractive force of plow and torque of engine output shaft and rear axle during plow operation in Seomyeon, Chuncheon. Test site has moisture content from 19.
대상 데이터
This study analyzed the tractive force of plow and torque of engine output shaft and rear axle during plow operation in Seomyeon, Chuncheon. Test site has moisture content from 19.5 to 24.2% and it was sandy with 90.9% of sand, 6.0% of silt and 3.1% of clay. 3-blades reversible plow was mounted on a tractor with 23.
In S-N curve, strengths for 103 cycle and 106 cycle were calculated by equation (5), and S-N line of the plowshare was drawn using linear relationship[12]. The material of plowshare used in test is SUP10, and ultimate strength is 1226 MPa according to JIS-G4801[13]. Since the ultimate strength is less than 1400 MPa, the fatigue strength was determined to be 613 MPa which is 0.
The used plow was 3-blades reversible plow, which is mainly used by farmers in Chuncheon, Gangwon-do. The plow used in the test is a hydraulic reversible plow which can reverse the soil right and left and had wide tilling width. Figure 2 and Table 2 show the shape and specifications of the plow.
The test site was located in Seomyeon, Chuncheon. The soil properties were analysed by soil samples randomly collected at 5 points of the site.
7 kW and rated rotational speed of 2600 rpm. The tractor had four main transmission gears (1, 2, 3, and 4), and three sub gears (L, M, and H). Minimum ground clearance is 345 mm, which has a high ground clearance and small size compared to products with the same output.
The tractor used in the test was an agricultural tractor with rated output of 23.7 kW and rated rotational speed of 2600 rpm. The tractor had four main transmission gears (1, 2, 3, and 4), and three sub gears (L, M, and H).
The used plow was 3-blades reversible plow, which is mainly used by farmers in Chuncheon, Gangwon-do. The plow used in the test is a hydraulic reversible plow which can reverse the soil right and left and had wide tilling width.
이론/모형
Also, the load must be converted to equivalent completely reversed load to determine fatigue life. The load spectrum of equivalent completely reversed load was constructed using Smith-Watson-Topper equation. (Equation (1))
The soil properties were analysed by soil samples randomly collected at 5 points of the site. The moisture content of the soil was determined using oven method[8] and the soil texture was determined using the U.S. Department of Agriculture (USDA) method. As the results of the soil properties analysis, the soil texture was sandy with 90.
성능/효과
1. The maximum traction forces were 9.85, 10.99, 13.256 and 17.534 kN under working speed L4, M1, M2 and M3, respectively. The tractive force increased as the working speed.
3. The cumulative damage sum of plowshare at M3 gear was 4.14 × 10-5 and estimated fatigue life was 805 hours.
4. Considering the annual plow operation time, the fatigue life of the plowshare was estimated to 38 years based on Kim et al.[18] and 8 years based on Kim et al.
Department of Agriculture (USDA) method. As the results of the soil properties analysis, the soil texture was sandy with 90.9% of sand, 6.0% of silt and 3.1% of clay and the moisture content ranged from 19.5 to 24.2%.
[3] analyzed max-min torque ratio for rear axle and engine output shaft in two level of working speed. This study verified the load variation on the engine output shaft is larger than that on the rear axle as well as in various working speed conditions.
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