- Email: [email protected]
Experimental investigation of bionic rough curved soil cutting blade surface to reduce soil adhesion and friction
Soil & Tillage Research 85 (2006) 1–12 www.elsevier.com/locate/still
Experimental investigation of bionic rough curved soil cutting blade surface to reduce soil adhesion and friction L.Q. Ren, Z.W. Han *, J.Q. Li, J. Tong Key Laboratory of Terrain-Machine Bionics Engineering (Jilin University), School for Biology and Agricultural Engineering, Jilin University (Nanling Campus), Ministry of Education, Changchun 130025, PR China Received 16 July 2003; received in revised form 31 August 2004; accepted 4 October 2004
Abstract The phenomenon of soil adhesion occurs often when machines interact with soil. Adhesion increases the working resistance and energy consumption of cutting or tillage tools and often decreases the working quality. The problem of soil adhesion has been solved by some soil-burrowing animals, such as the dung beetle, ant, pangolin and others. It was found that some exterior parts of soil-burrowing animals have geometrical rough structures, which was one of the reasons why soil-burrowing animals do not stick to the soil so much. In order to study the effects of the rough surface characteristics on bulldozer blades to reduce soil adhesion, several curved bulldozer blades with different ‘‘bionic’’ rough surface characteristics were designed and tested in comparison to smooth blades. In addition, the mean normal force on the blade surface was measured through small sensors mounted on certain points of the blade surface to study the soil to blade mechanics. The blades designed with rough surfaces were found to reduce the mean draft force. A considerable amount of soil adhered to the surface of the smooth blades, but little adhered to the rough blades. The mean normal pressure measured by the sensors mounted on the blade roughness convex curves was much larger than that between the convexes. The mean normal pressure was greatest on the blade bottom edge. # 2005 Elsevier B.V. All rights reserved. Keywords: Non-smooth surface; Bionic bulldozer blades; Resistance reduction; Anti-adhesion; Soil-burrowing animals
1. Introduction The phenomenon of soil adhesion occurs often when soil cutting or tillage machines interact with soil. Soil adhesion increases the working resistance and energy consumption of cutting or tillage tools and * Corresponding author. Tel.: +86 431 5095575; fax: +86 431 5095575. E-mail address: [email protected] (Z.W. Han).
often decreases the working quality. Soil adhesion, working resistance and abrasive wear are the three main problems of soil-engaging implements. Many methods, such as materials modification, surface coating, surface shape modification, vibration, lubrication, heating, a flexible structure, electro-osmosis and magnetization have been investigated in attempts to reduce soil adhesion forces between soil and implement surfaces. Some researchers found that polymeric materials and surface coatings had the
0167-1987/$ – see front matter # 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.still.2004.10.006
2
L.Q. Ren et al. / Soil & Tillage Research 85 (2006) 1–12
ability to reduce soil adhesion by 10–20% (Lu et al., 1996; Tong et al., 1994a; Salokhe et al., 1993; Jia et al., 1996; Liu et al., 1998), but the polymeric materials had poor abrasion resistance against soil (Tong et al., 1999). The surface shape of soil-engaging components can also play an important role in reducing soil adhesion and friction. A kind of passage-hole moldboard was made to reduce the plowing resistance by 13–17% (Zhu et al., 1992). Ultrasonic and mechanical vibration was found to reduce soil adhesion and friction by 20–30% (Sharma et al., 1977; Wang et al., 1998), as did injecting an airflow, water and polymer-water solutions between the soil and the implement surface producing a lubrication effect (Araya and Kawanishi, 1984; Schafer et al., 1977). Some soil-burrowing animals have flexible characteristics, which benefit their anti-adhesion and lower surface to soil resistance. The bionic flexible technology has been investigated and the results applied in practice. For example, a bionic flexible soil dumper, a bionic flexible excavator bucket, a bionic flexible shovel loader bucket and bionic flexible coal mine trucks, etc. (Sun et al., 1993; Wang et al., 1997; Ren et al., 1998; Yang and Ren, 2001). Electroosmosis has been found to reduce soil adhesion and sliding resistance, but a long contact time was required which limited its application (Mackson, 1962; Shirokov, 1954; Clyma and Larson, 1991; Cong et al., 1995; Chen et al., 1995; Ren et al., 2001a). The effect of a magnetic field on plowing resistance was studied (Tong et al., 2000b), and plowshares with permanent magnets attached on the back had lower plowing resistance by 13% and tractor fuel oil consumption than plows without magnetization (Han and Zhang, 1991; Guo and Liu, 1995).
that some parts of soil-burrowing animals’ body surfaces take the form of geometrically rough structures, and these rough structures are one of the important reasons why soil-burrowing animals did not stick to the soil. These structures are convex, concave, wavy and scaly shapes, etc. The size of structural units on these rough surfaces varies from 0.075 to 0.20 mm, and they are of benefit for the reduction of adhesion and surface frictional shear resistance reduction against soil. The rough structures on soil-burrowing animals’ body surfaces were scanned and analyzed by scanning electron-microscopy and visual stereomicroscopy, (Chen et al., 1992; Ren et al., 1992; Tong et al., 1994b; Cong et al., 1999; Cheng et al., 2002). Fig. 1 shows a dung beetle, and Fig. 2 illustrates the rough surface morphology of some animals. The characteristics of some soil-burrowing animals that reduce soil adhesion gives guidance to simulate such rough surfaces on soil-engaging component surfaces of soil cutting and tillage machines. Basic research on the principles of the rough surfaces of soil-burrowing animals has been done, and bionic rough surfaces have been investigated for soil-engaging implements (Ren et al., 1990, 2001b). Some bionic bulldozing plates and plows were designed and made to test the mechanics of rough surfaces (Ren et al., 1992, 1995; Qaisrani et al., 1992; Li et al., 1996). These researches were concerned with bionic rough plane bulldozing
2. Soil-burrowing animals and bionic rough surfaces Some soil-burrowing animals such as the dung beetle, ant, pangolin, earthworm, ground beetle, mole cricket, loach, earwig, locust, millipede and centipede move in moist or adhesive soil, but soil seldom sticks to their bodies. In order to adapt to their living environment, soil-burrowing animals have evolved several kinds of special body surface with different morphologies or mechanisms. Research has shown
Fig. 1. A dung beetle.
L.Q. Ren et al. / Soil & Tillage Research 85 (2006) 1–12
3
Fig. 2. The rough morphology of some typical animals (a) head surface of a kind of dung beetle, (b) surface of one species of mole cricket, (c) abdomen surface of a type of groud beetle and (d) surface of a pangolin squama.
blades, but none investigated the action of the normal force acting on the surface of the soil-engaging components. In this study, several kinds of curved bionic bulldozer blades with different rough surface characteristics were designed and tested to study their effects on the reduction of adhesion against soil. In addition, the normal pressure acting on the blade surface was measured through small load sensors mounted on particular points of the blade surface. The size of roughness units on the bulldozer blades is larger than on animals, but they were designed to follow similar principles.
3. Materials and methods 3.1. The bulldozer blade samples The sample bulldozer blade surfaces tested took the form of rough convex shapes and curved surfaces. The convex shapes are spherical. The small convex shapes were cast on the sample surfaces, and the overall geometric parameters of the samples are given in
Table 1. The distribution of the small convex shapes was different in quantity, base diameter, height and distribution in different samples. The roughness characteristic parameters of randomly distributed the samples are shown in Table 2. The design parameters of bionic rough samples (sample no. 7 and 8) are listed in Table 3. The blade samples were of 10 different types and comprised 32 pieces. The material of the blade sample was grey cast iron (type: HT200). The surfaces of all the blade samples were brushed between tests to keep them clean. Some of the bulldozer blade samples are shown in Fig. 3. Table 1 The structural parameters of the samples Parameter
Value
Bottom edge cutting angle from horizontal Length of blade (mm) Height of blade (mm) Width of blade (mm) Radius of blade (mm) Front straight edge thickness (mm) Width of blade edge (mm) Thickness of blade (mm)
468 300 150 150 105.2 25.3 40 15
4
L.Q. Ren et al. / Soil & Tillage Research 85 (2006) 1–12
Table 2 The roughness characteristic parameters of the samples No.
Type
Convex number
Convex diameter (mm)
Convex height (mm)
Convex distribution
Distance between convex centers (mm)
1 2 3 4 5 6 7 8 9 10
Smooth Rough Rough Rough Rough Rough Rough Rough Rough Rough
– 16 13 19 16 16 16 16 16 16
– 30 30 30 40 20 Range 20–40 30 30 30
– 4 4 4 4 4 4 4 2 8
– Regular Regular Regular Regular Regular Random Random Regular Regular
– 50 60 40 50 50 Random Random 50 50
3.2. Test soil
3.3. Test conditions and equipment
The test soil was black clay brought from Jilin Province of Northeast People’s Republic of China. The moisture content was 28.25 g (100 g) 1 of dry soil mass. The test soil was covered until the experiments were finished in order to keep the same moisture content. The particle size distribution, liquid limit and plastic limit of the soil are listed in Table 4.
The tests were conducted in the soil bin at Jilin University (Nanling Campus), People’s Republic of China. The dimensions of the soil bin were 2.5 m length, 0.815 m width and 0.515 m depth, and the bin was driven by an electric motor through gearboxes. In the experiments, each tested blade was mounted on a fixed frame structure above the soil bin, and as the soil bin moved the test blade cut the soil. The draft forces
Table 3 The design parameters of random bionic rough surfaces (sample no. 7 and 8) Convex number
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
Coordinates of convex center (mm) -X
Coordinates of convex center (mm) -Y
No. 7
No. 8
No. 7
No. 8
No. 7
No. 8
70.7 223.3 144.7 259.2 185.5 22.5 94.8 55.1 137.7 219.9 259.6 173.9 62.5 206.0 279.1 118.0
70.7 223.3 144.7 259.2 185.5 22.5 94.8 55.1 137.7 219.9 259.6 173.9 62.5 206.0 279.1 118.0
38.2 39.3 40.2 46.6 56.5 61.3 65.1 71.0 75.5 84.7 84.8 101.3 111.4 116.0 116.5 117.5
38.2 39.3 40.2 46.6 56.5 61.3 65.1 71.0 75.5 84.7 84.8 101.3 111.4 116.0 116.5 117.5
28.4 28.8 29.7 31.4 29.3 25.5 29.0 34.5 29.1 30.9 33.6 32.1 32.8 27.5 25.6 30.3
30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0
Max Min Average
34.5 25.5 29.9
30.0 30.0 30.0
Left bottom corner of blade (X, Y) = (0, 0)
Convex base diameter (mm)
L.Q. Ren et al. / Soil & Tillage Research 85 (2006) 1–12
5
Fig. 3. A photograph of test samples (a) some bulldozer blade samples and (b) samples used for tests.
Table 4 The particle size distribution of the tested soil, liquid limit (WL) and plastic limit (WP) Particle size distribution, (%) mass 0.074–0.05 mm 0.05–0.01 mm 0.01–0.005 mm 0.005–0.002 mm
35 42.5 12.5 10
WL (g (100 g) 1) WP (g (100 g) 1)
36.33 22.62
were measured through two octagonal ring dynamometers (Fig. 4) mounted between the tested blades and the fixed frame structure. The dynamometers were designed by authors and manufactured by professional factory. The draft force signals were conditioned from strain gages, recorded by a cassette data recorder, and then processed in a signal processor. In the
Fig. 5. The structure of load sensors (1) membrane, (2) shell, (3) strain gage and (4) lead wire.
experiments, the depth of cut was 15 mm, the speed of cut was 0.031 m s–1 and the tip rake angle was 468 to the horizontal. The normal pressure on the blades was measured through 12 load sensors mounted on specific points on the blade surfaces. The design of each sensor is illustrated in Fig. 5. All samples were tested under the same soil conditions, and every experiment was repeated three times.
4. Results and discussion 4.1. Effects of non-smooth characteristics on resistance reduction
Fig. 4. The structure of octagonal ring dynamometers.
4.1.1. Effects of the number of the rough convexes Sample no. 1 (smooth), no. 2 (number of convexes = 16), no. 3 (number of convexes = 13)
6
L.Q. Ren et al. / Soil & Tillage Research 85 (2006) 1–12
Fig. 6. Effects of convex numbers on average draft force.
Fig. 7. Effects of convex base diameter on average draft force.
and no. 4 (number of convexes = 19) had different number of convexes, and were chosen as samples for tests to study the effects of the number of the convex surface shapes. The experimental results of the mean draft forces of the four samples are shown in Fig. 6. It was obvious that the mean tested draft force of sample no. 3 was the lowest in this group, being 24% lower than that of the smooth sample no. 1. The mean tested draft force of sample no. 4 was 19% lower than that of the smooth sample no. 1. The smooth blade sample no. 1 had the highest mean tested draft force. Under the experimental conditions and the same parameters except number of convex shapes, a lower number of convex shapes were of benefit for the mean tested draft force reduction. But sample no. 4 (19 shapes) had lower draft than sample no. 2 (16 shapes).
diameter, a larger convex base diameter gave more reduction of draft force.
4.1.2. Effects of the base diameter of the rough convexes Sample no. 1 (smooth), no. 2 (convex base diameter = 30 mm), no. 5 (convex base diameter = 40 mm) and no. 6 (convex base diameter = 20 mm) were selected to study the effects of the base diameter of the surface convex shapes in test conditions identical to those mentioned above. The mean draft forces of these samples are illustrated in Fig. 7. The mean draft force of sample no. 5 was the lowest in this group, being 33% lower than that of the smooth sample no. 1. The mean draft force of sample no. 6 was 20% lower than that of sample no. 1. Smooth sample no. 1 had the highest mean tested draft force. Under the experimental conditions and the same parameters except for convex base
4.1.3. Effects of the distribution of the rough convexes Under the same soil and test conditions, the mean draft force of samples no. 1 (smooth), no. 2 (convex base diameter = 30 mm), no. 7 (convex distribution random and convex base diameter normal) and no. 8 (convex distribution random and convex base diameter = 30 mm) are plotted in Fig. 8. It was found that the mean draft force of sample no. 7 was the lowest in this group, being 14% lower than that of the smooth sample no. 1. The mean draft force of sample no. 8 was about 1% lower than that of sample no. 1. Smooth sample no. 1 had the highest mean draft force. Under
Fig. 8. Effects of convex distribution on average draft force.
L.Q. Ren et al. / Soil & Tillage Research 85 (2006) 1–12
7
Fig. 9. Effects of convex height on average draft force. Fig. 10. Soil adhesion state of sample no. 1 repeated eight times.
the experimental conditions and the same parameters except convex distribution, the sample with the characteristics of convex distribution and random, convex base diameter gave more reduction of tested draft force. 4.1.4. Effects of the height of the rough convexes The effects of difference in rough convex height were investigated under the same soil and tested conditions for sample no. 1 (smooth), no. 2 (convex height = 4 mm), no. 9 (convex height = 8 mm) and no. 10 (convex height = 2 mm). The mean draft forces of these samples are illustrated in Fig. 9. It is obvious that the mean tested draft force of sample no. 9 was the lowest in this group. It was 19% lower than that of the smooth sample no. 1. The mean tested draft force of sample no. 10 was 12% lower than that of the smooth one. Sample no. 1 had the highest mean tested draft force. Under the experimental conditions and the same parameters except convex height, the higher convex shape had good ability to reduce the mean tested draft force.
Fig. 11. Soil adhesion state of sample no. 7 repeated eight times and not cleaned between tests.
4.2. Effect of number of repeated passes on soil adhesion and draft forces Under the same soil and test conditions as the above, experiments for samples no. 1 and no. 7 were conducted eight times in succession. After every experiment, the surfaces of the tested samples were not treated. The soil that adhered to the surfaces of the two samples is shown in Figs. 10 and 11. The mean draft and vertical forces of the two samples were
Fig. 12. Relationship between draft forces and experimental repetitions for two samples.
8
L.Q. Ren et al. / Soil & Tillage Research 85 (2006) 1–12
Fig. 13. Relationship between vertical forces and experimental repetitions for two samples. Fig. 15. Structure and sensor distribution of sample no. 3.
measured, and these are shown in Figs. 12 and 13, respectively. A considerable amount of soil adhered to the surface of sample no. 1, and very little soil adhered to the surface of sample no. 7. It can be seen in Figs. 12 and 13 that the mean draft force and vertical force of sample no. 7 were always lower than those of sample no. 1. For sample no. 1, the mean draft force increased with test repetitions, showing presumably a phenomenon of cumulative adhesion. However, the mean tested draft force of sample no. 7 varied less probably because of little soil adhesion to its surface shown in Fig. 11. 4.3. Mean normal pressure measurements The structure and distribution of pressure sensors for blade samples nos. 2, 3, 5 and 7 are illustrated in
Figs. 14–17. In these four figures, the large circles represent convex shapes added onto each blade, and the small circles with numbers in the centers represent the pressure sensors. Samples nos. 2, 3, 5 and 7 had different roughness characteristics of convex number, size and distribution. The normal pressure acting on the different sensors positions on these samples are shown in Figs. 18–21. Some of the sensors were mounted on the convex shapes and some were mounted between. The normal pressure on each position was measured three times to get the mean value. The mean measured normal pressure on the convex shapes (such as point 2, point 6 and point 10) was much larger than that measured between the convexes. The mean measured normal
Fig. 14. Structure and sensor distribution of sample no. 2.
L.Q. Ren et al. / Soil & Tillage Research 85 (2006) 1–12
Fig. 16. Structure and sensor distribution of sample no. 5.
Fig. 17. Structure and sensor distribution of sample no. 7.
Fig. 19. Average normal pressure distribution of sample no. 3.
Fig. 18. Average normal pressure distribution of sample no. 2.
9
10
L.Q. Ren et al. / Soil & Tillage Research 85 (2006) 1–12
Fig. 20. Average normal pressure distribution of sample no. 5.
pressure near the lower edge part of the bulldozer blade (such as point 12) was the largest. The largest mean measured pressure on sample no. 5 was smaller than that of all other blades, and it had good ability of resistance reduction against soil. It was shown that increasing the size of convex shapes on a bulldozer blade surface may be useful for reductions in the soil mean normal force and shear resistance. Although the largest normal pressure value on blade no. 7 was not the smallest of all blades, it had the lowest draft. In general, normal pressure controls soil to metal friction. In this experiment, the effect of normal pressure on soil adhesion was studied. It was found that there were a little effects of normal pressure on soil adhesion to some extent.
Fig. 21. Average normal pressure distribution of sample no. 7.
5. Conclusions The mean measured draft forces of the curved bulldozer blade samples tested with rough surfaces were lower than those on the sample with a smooth surface. It was found that the samples with a rough surface could reduce draft force in this study. The factors affecting the cutting resistance of the bionic bulldozer blades included the number of the rough convex shapes, the convex base diameter, distribution of shapes and convex height. The sample with the largest convex base diameter had the smallest mean draft force. In the same soil and test conditions, there was a considerable amount of soil that adhered to the surface of the smooth blade, but the rough blade had little adhered soil. The mean measured draft force and vertical force of the rough blades were lower than that on the smooth one. The mean measured draft force of the smooth samples increased some 23% after eight cutting repetitions, but the mean measured draft force of the rough blade increased only 15% in eight repeated passes. Under the experimental conditions with the same cutting velocity, depth of cut and angle of cut, it was found that the mean measured normal pressure acting on the convexes was two–four times larger than that between the convexes. The mean measured normal pressure at the edge of the bulldozer blade was the largest of all. The blades with larger convex shape size had the smallest mean normal pressure and the smallest mean
L.Q. Ren et al. / Soil & Tillage Research 85 (2006) 1–12
draft force. The sample with randomly distributed convex shapes did not have the smallest mean normal pressure, but it resulted in the lowest draft. It was found in the experiments that the rough ‘‘bionic’’ blade surface designed reasonably was benefit to reduce soil adhesion and friction, and it was very useful in agricultural tillage as well as construction earthmoving.
Acknowledgements The authors are grateful for the financial support provided by the Key Project of Chinese Ministry of Education (Grant No. 02089), Trans-Century Training Program Foundation for the Talents by Chinese Ministry of Education (Grant No. 20030720), the Foundation for Distinguished Young Scholars of Jilin Province (Grant No. 6-21-4), the National Science Fund for Distinguished Young Scholars of China (Grant No. 50025516), and the National Key Grant Program of Basic (Grant No. 2002CCA01200).
References Araya, K., Kawanishi, K., 1984. Soil failure by introduction air under pressure. Trans. ASAE 27, 1292–1297. Chen, B.C., Ren, L.Q., Xu, X.M., Cui, X.X., 1992. Research on reducing soil adhesion of body surface of typical soil animals. Trans. CSAE 6 (2), 1–6 (in Chinese). Chen, B.C., Liu, D.W., Ning, S.J., Cong, Q., 1995. Research on the reducing adhesion and scouring of soil of lugs by using unsmoothed surface electro-osmosis method. Trans. CSAE 11 (3), 29–33 (in Chinese). Cheng, H., Sun, J.R., Li, J.Q., Ren, L.Q., 2002. Structure of the integumentary surface of the dung beetle and its relation to nonadhesion of substrate particles. Acta Entomol. Sin. 45 (2), 175– 181 (in Chinese). Clyma, H.E., Larson, D.L., 1991. Evaluating the effectiveness of electro-osmosis in reducing tillage draft force, St. Joseph, Mich. ASAE, ASAE Paper No. 91-3533. Cong, Q., Wu, L.K., Ren, L.Q., Chen, B.C., 1995. The principle experiment of reducing soil adhesion and scouring soil by nonsmooth surface electro-osmosis. Trans. CSAE 11 (3), 19–23 (in Chinese). Cong, Q., Ren, L.Q., Chen, B.C., Yan, B.Z., 1999. Using characteristics of burrowing animals to reduce soil-tool adhesion. Trans. ASAE 42, 1549–1556. Guo, P., Liu, J., 1995. The effect of magnetized plowshare upon tillage performance. Agric. Res. Afrid Areas 13 (2), 103–109 (in Chinese).
11
Han, G., Zhang, Y., 1991. Measurement and analysis of ploughing resistance on the magnetic plough. Trans. CSAM 22 (3), 25–28 (in Chinese). Jia, X., Ren, L.Q., Chen, B.C., 1996. Characteristics of bionic composite coating reducing adhesion and resistance. Chin. J. Mater. Res. 10 (2), 210–214 (in Chinese). Li, J.Q., Ren, L.Q., Liu, C.Z., Chen, B.C., 1996. A study on the bionic moldboard plow of reducing soil adhesion and plowing resistance. Trans. CSAE 27 (2), 1–4 (in Chinese). Liu, C.Z., Ren, L.Q., Tong, J., Feng, Y.J., 1998. Soil adhesion of UHMWPE and its composite materials. Trans. CSAE 14 (4), 37– 41 (in Chinese). Lu, X.C., Wen, X.Z., Tong, J., Chen, Y., Ren, L.Q., 1996. Wettability, soil adhesion, abrasion and friction wear of PTF (+PPS) + Al2O3 composites. Wear 193, 48–55. Mackson, C.J., 1962. The effect of electro-osmosis on soil to steel sliding friction as influenced by speed, voltage and soil moisture, St. Joseph, Mich. ASAE, ASAE Paper No.62-650 Qaisrani, A.R., Ren, L.Q., Chen, B.C., 1992. Modified and unsmoothed plow surfaces—a means to reduce plowing resistance. Int. Agric. Eng. J. 1 (3), 115–124. Ren, L.Q., Chen, D.X., Hu, J.G., Wang, L., 1990. Initial exploring for mechanism of decreasing resistance and reducing adhesion of the bionic bulldozing plates. Trans. CSAE 6 (2), 13–20 (in Chinese). Ren, L.Q., Cong, Q., Chen, B.C., Wu, L.K., Li, A.Q., Jing, D., 1992. A study on the adhesion reducing character of geometric nonsmooth surface of typical animal. Trans. CSAM 23 (2), 29–35 (in Chinese). Ren, L.Q., Tong, J., Zhang, S.J., Chen, B.C., 1995. Reducing sliding resistance of soil against bulldozing plates by unsmoothed bionics surfaces. J. Terramech. 32, 303–309. Ren, L.Q., Wang, Y.P., Li, J.Q., Tong, J., 1998. Flexible unsmoothed cuticles of soil animals and their characteristics of reducing adhesion and resistance. Chin. Sci. Bull. 43 (2), 166– 1169. Ren, L.Q., Cong, Q., Tong, J., Chen, B.C., 2001a. Reducing adhesion of soil against loading shovel using bionic electro-osmosis method. J. Terramech. 38, 211–219. Ren, L.Q., Tong, J., Li, J.Q., Chen, B.C., 2001b. Soil adhesion and biomimetics of soil-engaging components: a review. J. Agric. Eng. Res. 79 (3), 239–263. Salokhe, V.M., Hoki, M., Sato, K., 1993. Why soil does not stick to enamel coating? J. Terramech. 30 (4), 275–283. Schafer, R.L., Gill, W.R., Reaves, C.A., 1977. Lubrication plows vs. sticky soil. Agric. Eng. 58 (10), 34–38. Sharma, V.K., Drew, L.O., Nelson, G.L., 1977. High frequency vibrational effects on soil-metal friction. Trans. ASAE 20, 46– 51. Shirokov, B.I., 1954. Problem of the utilization of electro-osmosis of soil in plowing, USDA Eng. Translation A888. USDA, Washington, DC. Sun, S.Y., Ren, L.Q., Tong, J., Chen, P., 1993. Study of a shovel bucket with steel-cloth pocket by bionics. Trans. CSAM 24 (4), 18–22 (in Chinese). Tong, J., Ren, L.Q., Chen, Y., Qaisrani, A.R., Chen, B.C., 1994a. Abrasive properties and mechanism of polytetra fluoroethylene
12
L.Q. Ren et al. / Soil & Tillage Research 85 (2006) 1–12
and ultra high molecular weight polyethylene. Tribol. Int. 14, 65–72. Tong, J., Ren, L.Q., Chen, B.C., 1994b. Geometrical morphology, chemical constitution and wettability of body surfaces of soil animals. Int. Agric. Eng. J. 3 (1–2), 59–68. Tong, J., Ren, L.Q., Yan, J.L., Ma, Y.H., Chen, B.C., 1999. Adhesion and abrasion of several materials against soil. Int. Agric. Eng. J. 8 (1), 1–22. Tong, J., Wang, X.Y., Yan, J.L., Han, Z.W., Ren, L.Q., 2000b.Effects of magnetic-field upon soil adhesion and friction, Proceedings of International Agriculture Engineering Conference, 4–7 December, Bangkok, Thailand, pp. 66–72.
Wang, X.L., Ito, N., Kito, K., Garcia, P.P., 1998. Study on use of vibration to reduce soil adhesion. J. Terramech. 35 (2), 87– 101. Wang, Y.P., Ren, L.Q., Li, J.Q., Sun, S.Y., Han, Z.M., 1997. Field test study on flexible bionics technologies of anti-adhesion to dump trucks. Trans. CSAE 13 (3), 128–132 (in Chinese). Yang, X.D., Ren, L.Q., 2001. Experimental study and system model of bionic flexible resistance reduction. Chin. Mech. Eng. 12 (8), 951–953 (in Chinese). Zhu, H., Tan, L., Wu, S., 1992. An experimental study on the ‘‘comet type passage-holes’’ plough of reducing resistance. Trans. CSAM 23 (4), 20–24 (in Chinese).
Experimental investigation of bionic rough curved soil cutting blade surface to reduce soil adhesion and friction L.Q. Ren, Z.W. Han *, J.Q. Li, J. Tong Key Laboratory of Terrain-Machine Bionics Engineering (Jilin University), School for Biology and Agricultural Engineering, Jilin University (Nanling Campus), Ministry of Education, Changchun 130025, PR China Received 16 July 2003; received in revised form 31 August 2004; accepted 4 October 2004
Abstract The phenomenon of soil adhesion occurs often when machines interact with soil. Adhesion increases the working resistance and energy consumption of cutting or tillage tools and often decreases the working quality. The problem of soil adhesion has been solved by some soil-burrowing animals, such as the dung beetle, ant, pangolin and others. It was found that some exterior parts of soil-burrowing animals have geometrical rough structures, which was one of the reasons why soil-burrowing animals do not stick to the soil so much. In order to study the effects of the rough surface characteristics on bulldozer blades to reduce soil adhesion, several curved bulldozer blades with different ‘‘bionic’’ rough surface characteristics were designed and tested in comparison to smooth blades. In addition, the mean normal force on the blade surface was measured through small sensors mounted on certain points of the blade surface to study the soil to blade mechanics. The blades designed with rough surfaces were found to reduce the mean draft force. A considerable amount of soil adhered to the surface of the smooth blades, but little adhered to the rough blades. The mean normal pressure measured by the sensors mounted on the blade roughness convex curves was much larger than that between the convexes. The mean normal pressure was greatest on the blade bottom edge. # 2005 Elsevier B.V. All rights reserved. Keywords: Non-smooth surface; Bionic bulldozer blades; Resistance reduction; Anti-adhesion; Soil-burrowing animals
1. Introduction The phenomenon of soil adhesion occurs often when soil cutting or tillage machines interact with soil. Soil adhesion increases the working resistance and energy consumption of cutting or tillage tools and * Corresponding author. Tel.: +86 431 5095575; fax: +86 431 5095575. E-mail address: [email protected] (Z.W. Han).
often decreases the working quality. Soil adhesion, working resistance and abrasive wear are the three main problems of soil-engaging implements. Many methods, such as materials modification, surface coating, surface shape modification, vibration, lubrication, heating, a flexible structure, electro-osmosis and magnetization have been investigated in attempts to reduce soil adhesion forces between soil and implement surfaces. Some researchers found that polymeric materials and surface coatings had the
0167-1987/$ – see front matter # 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.still.2004.10.006
2
L.Q. Ren et al. / Soil & Tillage Research 85 (2006) 1–12
ability to reduce soil adhesion by 10–20% (Lu et al., 1996; Tong et al., 1994a; Salokhe et al., 1993; Jia et al., 1996; Liu et al., 1998), but the polymeric materials had poor abrasion resistance against soil (Tong et al., 1999). The surface shape of soil-engaging components can also play an important role in reducing soil adhesion and friction. A kind of passage-hole moldboard was made to reduce the plowing resistance by 13–17% (Zhu et al., 1992). Ultrasonic and mechanical vibration was found to reduce soil adhesion and friction by 20–30% (Sharma et al., 1977; Wang et al., 1998), as did injecting an airflow, water and polymer-water solutions between the soil and the implement surface producing a lubrication effect (Araya and Kawanishi, 1984; Schafer et al., 1977). Some soil-burrowing animals have flexible characteristics, which benefit their anti-adhesion and lower surface to soil resistance. The bionic flexible technology has been investigated and the results applied in practice. For example, a bionic flexible soil dumper, a bionic flexible excavator bucket, a bionic flexible shovel loader bucket and bionic flexible coal mine trucks, etc. (Sun et al., 1993; Wang et al., 1997; Ren et al., 1998; Yang and Ren, 2001). Electroosmosis has been found to reduce soil adhesion and sliding resistance, but a long contact time was required which limited its application (Mackson, 1962; Shirokov, 1954; Clyma and Larson, 1991; Cong et al., 1995; Chen et al., 1995; Ren et al., 2001a). The effect of a magnetic field on plowing resistance was studied (Tong et al., 2000b), and plowshares with permanent magnets attached on the back had lower plowing resistance by 13% and tractor fuel oil consumption than plows without magnetization (Han and Zhang, 1991; Guo and Liu, 1995).
that some parts of soil-burrowing animals’ body surfaces take the form of geometrically rough structures, and these rough structures are one of the important reasons why soil-burrowing animals did not stick to the soil. These structures are convex, concave, wavy and scaly shapes, etc. The size of structural units on these rough surfaces varies from 0.075 to 0.20 mm, and they are of benefit for the reduction of adhesion and surface frictional shear resistance reduction against soil. The rough structures on soil-burrowing animals’ body surfaces were scanned and analyzed by scanning electron-microscopy and visual stereomicroscopy, (Chen et al., 1992; Ren et al., 1992; Tong et al., 1994b; Cong et al., 1999; Cheng et al., 2002). Fig. 1 shows a dung beetle, and Fig. 2 illustrates the rough surface morphology of some animals. The characteristics of some soil-burrowing animals that reduce soil adhesion gives guidance to simulate such rough surfaces on soil-engaging component surfaces of soil cutting and tillage machines. Basic research on the principles of the rough surfaces of soil-burrowing animals has been done, and bionic rough surfaces have been investigated for soil-engaging implements (Ren et al., 1990, 2001b). Some bionic bulldozing plates and plows were designed and made to test the mechanics of rough surfaces (Ren et al., 1992, 1995; Qaisrani et al., 1992; Li et al., 1996). These researches were concerned with bionic rough plane bulldozing
2. Soil-burrowing animals and bionic rough surfaces Some soil-burrowing animals such as the dung beetle, ant, pangolin, earthworm, ground beetle, mole cricket, loach, earwig, locust, millipede and centipede move in moist or adhesive soil, but soil seldom sticks to their bodies. In order to adapt to their living environment, soil-burrowing animals have evolved several kinds of special body surface with different morphologies or mechanisms. Research has shown
Fig. 1. A dung beetle.
L.Q. Ren et al. / Soil & Tillage Research 85 (2006) 1–12
3
Fig. 2. The rough morphology of some typical animals (a) head surface of a kind of dung beetle, (b) surface of one species of mole cricket, (c) abdomen surface of a type of groud beetle and (d) surface of a pangolin squama.
blades, but none investigated the action of the normal force acting on the surface of the soil-engaging components. In this study, several kinds of curved bionic bulldozer blades with different rough surface characteristics were designed and tested to study their effects on the reduction of adhesion against soil. In addition, the normal pressure acting on the blade surface was measured through small load sensors mounted on particular points of the blade surface. The size of roughness units on the bulldozer blades is larger than on animals, but they were designed to follow similar principles.
3. Materials and methods 3.1. The bulldozer blade samples The sample bulldozer blade surfaces tested took the form of rough convex shapes and curved surfaces. The convex shapes are spherical. The small convex shapes were cast on the sample surfaces, and the overall geometric parameters of the samples are given in
Table 1. The distribution of the small convex shapes was different in quantity, base diameter, height and distribution in different samples. The roughness characteristic parameters of randomly distributed the samples are shown in Table 2. The design parameters of bionic rough samples (sample no. 7 and 8) are listed in Table 3. The blade samples were of 10 different types and comprised 32 pieces. The material of the blade sample was grey cast iron (type: HT200). The surfaces of all the blade samples were brushed between tests to keep them clean. Some of the bulldozer blade samples are shown in Fig. 3. Table 1 The structural parameters of the samples Parameter
Value
Bottom edge cutting angle from horizontal Length of blade (mm) Height of blade (mm) Width of blade (mm) Radius of blade (mm) Front straight edge thickness (mm) Width of blade edge (mm) Thickness of blade (mm)
468 300 150 150 105.2 25.3 40 15
4
L.Q. Ren et al. / Soil & Tillage Research 85 (2006) 1–12
Table 2 The roughness characteristic parameters of the samples No.
Type
Convex number
Convex diameter (mm)
Convex height (mm)
Convex distribution
Distance between convex centers (mm)
1 2 3 4 5 6 7 8 9 10
Smooth Rough Rough Rough Rough Rough Rough Rough Rough Rough
– 16 13 19 16 16 16 16 16 16
– 30 30 30 40 20 Range 20–40 30 30 30
– 4 4 4 4 4 4 4 2 8
– Regular Regular Regular Regular Regular Random Random Regular Regular
– 50 60 40 50 50 Random Random 50 50
3.2. Test soil
3.3. Test conditions and equipment
The test soil was black clay brought from Jilin Province of Northeast People’s Republic of China. The moisture content was 28.25 g (100 g) 1 of dry soil mass. The test soil was covered until the experiments were finished in order to keep the same moisture content. The particle size distribution, liquid limit and plastic limit of the soil are listed in Table 4.
The tests were conducted in the soil bin at Jilin University (Nanling Campus), People’s Republic of China. The dimensions of the soil bin were 2.5 m length, 0.815 m width and 0.515 m depth, and the bin was driven by an electric motor through gearboxes. In the experiments, each tested blade was mounted on a fixed frame structure above the soil bin, and as the soil bin moved the test blade cut the soil. The draft forces
Table 3 The design parameters of random bionic rough surfaces (sample no. 7 and 8) Convex number
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
Coordinates of convex center (mm) -X
Coordinates of convex center (mm) -Y
No. 7
No. 8
No. 7
No. 8
No. 7
No. 8
70.7 223.3 144.7 259.2 185.5 22.5 94.8 55.1 137.7 219.9 259.6 173.9 62.5 206.0 279.1 118.0
70.7 223.3 144.7 259.2 185.5 22.5 94.8 55.1 137.7 219.9 259.6 173.9 62.5 206.0 279.1 118.0
38.2 39.3 40.2 46.6 56.5 61.3 65.1 71.0 75.5 84.7 84.8 101.3 111.4 116.0 116.5 117.5
38.2 39.3 40.2 46.6 56.5 61.3 65.1 71.0 75.5 84.7 84.8 101.3 111.4 116.0 116.5 117.5
28.4 28.8 29.7 31.4 29.3 25.5 29.0 34.5 29.1 30.9 33.6 32.1 32.8 27.5 25.6 30.3
30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0
Max Min Average
34.5 25.5 29.9
30.0 30.0 30.0
Left bottom corner of blade (X, Y) = (0, 0)
Convex base diameter (mm)
L.Q. Ren et al. / Soil & Tillage Research 85 (2006) 1–12
5
Fig. 3. A photograph of test samples (a) some bulldozer blade samples and (b) samples used for tests.
Table 4 The particle size distribution of the tested soil, liquid limit (WL) and plastic limit (WP) Particle size distribution, (%) mass 0.074–0.05 mm 0.05–0.01 mm 0.01–0.005 mm 0.005–0.002 mm
35 42.5 12.5 10
WL (g (100 g) 1) WP (g (100 g) 1)
36.33 22.62
were measured through two octagonal ring dynamometers (Fig. 4) mounted between the tested blades and the fixed frame structure. The dynamometers were designed by authors and manufactured by professional factory. The draft force signals were conditioned from strain gages, recorded by a cassette data recorder, and then processed in a signal processor. In the
Fig. 5. The structure of load sensors (1) membrane, (2) shell, (3) strain gage and (4) lead wire.
experiments, the depth of cut was 15 mm, the speed of cut was 0.031 m s–1 and the tip rake angle was 468 to the horizontal. The normal pressure on the blades was measured through 12 load sensors mounted on specific points on the blade surfaces. The design of each sensor is illustrated in Fig. 5. All samples were tested under the same soil conditions, and every experiment was repeated three times.
4. Results and discussion 4.1. Effects of non-smooth characteristics on resistance reduction
Fig. 4. The structure of octagonal ring dynamometers.
4.1.1. Effects of the number of the rough convexes Sample no. 1 (smooth), no. 2 (number of convexes = 16), no. 3 (number of convexes = 13)
6
L.Q. Ren et al. / Soil & Tillage Research 85 (2006) 1–12
Fig. 6. Effects of convex numbers on average draft force.
Fig. 7. Effects of convex base diameter on average draft force.
and no. 4 (number of convexes = 19) had different number of convexes, and were chosen as samples for tests to study the effects of the number of the convex surface shapes. The experimental results of the mean draft forces of the four samples are shown in Fig. 6. It was obvious that the mean tested draft force of sample no. 3 was the lowest in this group, being 24% lower than that of the smooth sample no. 1. The mean tested draft force of sample no. 4 was 19% lower than that of the smooth sample no. 1. The smooth blade sample no. 1 had the highest mean tested draft force. Under the experimental conditions and the same parameters except number of convex shapes, a lower number of convex shapes were of benefit for the mean tested draft force reduction. But sample no. 4 (19 shapes) had lower draft than sample no. 2 (16 shapes).
diameter, a larger convex base diameter gave more reduction of draft force.
4.1.2. Effects of the base diameter of the rough convexes Sample no. 1 (smooth), no. 2 (convex base diameter = 30 mm), no. 5 (convex base diameter = 40 mm) and no. 6 (convex base diameter = 20 mm) were selected to study the effects of the base diameter of the surface convex shapes in test conditions identical to those mentioned above. The mean draft forces of these samples are illustrated in Fig. 7. The mean draft force of sample no. 5 was the lowest in this group, being 33% lower than that of the smooth sample no. 1. The mean draft force of sample no. 6 was 20% lower than that of sample no. 1. Smooth sample no. 1 had the highest mean tested draft force. Under the experimental conditions and the same parameters except for convex base
4.1.3. Effects of the distribution of the rough convexes Under the same soil and test conditions, the mean draft force of samples no. 1 (smooth), no. 2 (convex base diameter = 30 mm), no. 7 (convex distribution random and convex base diameter normal) and no. 8 (convex distribution random and convex base diameter = 30 mm) are plotted in Fig. 8. It was found that the mean draft force of sample no. 7 was the lowest in this group, being 14% lower than that of the smooth sample no. 1. The mean draft force of sample no. 8 was about 1% lower than that of sample no. 1. Smooth sample no. 1 had the highest mean draft force. Under
Fig. 8. Effects of convex distribution on average draft force.
L.Q. Ren et al. / Soil & Tillage Research 85 (2006) 1–12
7
Fig. 9. Effects of convex height on average draft force. Fig. 10. Soil adhesion state of sample no. 1 repeated eight times.
the experimental conditions and the same parameters except convex distribution, the sample with the characteristics of convex distribution and random, convex base diameter gave more reduction of tested draft force. 4.1.4. Effects of the height of the rough convexes The effects of difference in rough convex height were investigated under the same soil and tested conditions for sample no. 1 (smooth), no. 2 (convex height = 4 mm), no. 9 (convex height = 8 mm) and no. 10 (convex height = 2 mm). The mean draft forces of these samples are illustrated in Fig. 9. It is obvious that the mean tested draft force of sample no. 9 was the lowest in this group. It was 19% lower than that of the smooth sample no. 1. The mean tested draft force of sample no. 10 was 12% lower than that of the smooth one. Sample no. 1 had the highest mean tested draft force. Under the experimental conditions and the same parameters except convex height, the higher convex shape had good ability to reduce the mean tested draft force.
Fig. 11. Soil adhesion state of sample no. 7 repeated eight times and not cleaned between tests.
4.2. Effect of number of repeated passes on soil adhesion and draft forces Under the same soil and test conditions as the above, experiments for samples no. 1 and no. 7 were conducted eight times in succession. After every experiment, the surfaces of the tested samples were not treated. The soil that adhered to the surfaces of the two samples is shown in Figs. 10 and 11. The mean draft and vertical forces of the two samples were
Fig. 12. Relationship between draft forces and experimental repetitions for two samples.
8
L.Q. Ren et al. / Soil & Tillage Research 85 (2006) 1–12
Fig. 13. Relationship between vertical forces and experimental repetitions for two samples. Fig. 15. Structure and sensor distribution of sample no. 3.
measured, and these are shown in Figs. 12 and 13, respectively. A considerable amount of soil adhered to the surface of sample no. 1, and very little soil adhered to the surface of sample no. 7. It can be seen in Figs. 12 and 13 that the mean draft force and vertical force of sample no. 7 were always lower than those of sample no. 1. For sample no. 1, the mean draft force increased with test repetitions, showing presumably a phenomenon of cumulative adhesion. However, the mean tested draft force of sample no. 7 varied less probably because of little soil adhesion to its surface shown in Fig. 11. 4.3. Mean normal pressure measurements The structure and distribution of pressure sensors for blade samples nos. 2, 3, 5 and 7 are illustrated in
Figs. 14–17. In these four figures, the large circles represent convex shapes added onto each blade, and the small circles with numbers in the centers represent the pressure sensors. Samples nos. 2, 3, 5 and 7 had different roughness characteristics of convex number, size and distribution. The normal pressure acting on the different sensors positions on these samples are shown in Figs. 18–21. Some of the sensors were mounted on the convex shapes and some were mounted between. The normal pressure on each position was measured three times to get the mean value. The mean measured normal pressure on the convex shapes (such as point 2, point 6 and point 10) was much larger than that measured between the convexes. The mean measured normal
Fig. 14. Structure and sensor distribution of sample no. 2.
L.Q. Ren et al. / Soil & Tillage Research 85 (2006) 1–12
Fig. 16. Structure and sensor distribution of sample no. 5.
Fig. 17. Structure and sensor distribution of sample no. 7.
Fig. 19. Average normal pressure distribution of sample no. 3.
Fig. 18. Average normal pressure distribution of sample no. 2.
9
10
L.Q. Ren et al. / Soil & Tillage Research 85 (2006) 1–12
Fig. 20. Average normal pressure distribution of sample no. 5.
pressure near the lower edge part of the bulldozer blade (such as point 12) was the largest. The largest mean measured pressure on sample no. 5 was smaller than that of all other blades, and it had good ability of resistance reduction against soil. It was shown that increasing the size of convex shapes on a bulldozer blade surface may be useful for reductions in the soil mean normal force and shear resistance. Although the largest normal pressure value on blade no. 7 was not the smallest of all blades, it had the lowest draft. In general, normal pressure controls soil to metal friction. In this experiment, the effect of normal pressure on soil adhesion was studied. It was found that there were a little effects of normal pressure on soil adhesion to some extent.
Fig. 21. Average normal pressure distribution of sample no. 7.
5. Conclusions The mean measured draft forces of the curved bulldozer blade samples tested with rough surfaces were lower than those on the sample with a smooth surface. It was found that the samples with a rough surface could reduce draft force in this study. The factors affecting the cutting resistance of the bionic bulldozer blades included the number of the rough convex shapes, the convex base diameter, distribution of shapes and convex height. The sample with the largest convex base diameter had the smallest mean draft force. In the same soil and test conditions, there was a considerable amount of soil that adhered to the surface of the smooth blade, but the rough blade had little adhered soil. The mean measured draft force and vertical force of the rough blades were lower than that on the smooth one. The mean measured draft force of the smooth samples increased some 23% after eight cutting repetitions, but the mean measured draft force of the rough blade increased only 15% in eight repeated passes. Under the experimental conditions with the same cutting velocity, depth of cut and angle of cut, it was found that the mean measured normal pressure acting on the convexes was two–four times larger than that between the convexes. The mean measured normal pressure at the edge of the bulldozer blade was the largest of all. The blades with larger convex shape size had the smallest mean normal pressure and the smallest mean
L.Q. Ren et al. / Soil & Tillage Research 85 (2006) 1–12
draft force. The sample with randomly distributed convex shapes did not have the smallest mean normal pressure, but it resulted in the lowest draft. It was found in the experiments that the rough ‘‘bionic’’ blade surface designed reasonably was benefit to reduce soil adhesion and friction, and it was very useful in agricultural tillage as well as construction earthmoving.
Acknowledgements The authors are grateful for the financial support provided by the Key Project of Chinese Ministry of Education (Grant No. 02089), Trans-Century Training Program Foundation for the Talents by Chinese Ministry of Education (Grant No. 20030720), the Foundation for Distinguished Young Scholars of Jilin Province (Grant No. 6-21-4), the National Science Fund for Distinguished Young Scholars of China (Grant No. 50025516), and the National Key Grant Program of Basic (Grant No. 2002CCA01200).
References Araya, K., Kawanishi, K., 1984. Soil failure by introduction air under pressure. Trans. ASAE 27, 1292–1297. Chen, B.C., Ren, L.Q., Xu, X.M., Cui, X.X., 1992. Research on reducing soil adhesion of body surface of typical soil animals. Trans. CSAE 6 (2), 1–6 (in Chinese). Chen, B.C., Liu, D.W., Ning, S.J., Cong, Q., 1995. Research on the reducing adhesion and scouring of soil of lugs by using unsmoothed surface electro-osmosis method. Trans. CSAE 11 (3), 29–33 (in Chinese). Cheng, H., Sun, J.R., Li, J.Q., Ren, L.Q., 2002. Structure of the integumentary surface of the dung beetle and its relation to nonadhesion of substrate particles. Acta Entomol. Sin. 45 (2), 175– 181 (in Chinese). Clyma, H.E., Larson, D.L., 1991. Evaluating the effectiveness of electro-osmosis in reducing tillage draft force, St. Joseph, Mich. ASAE, ASAE Paper No. 91-3533. Cong, Q., Wu, L.K., Ren, L.Q., Chen, B.C., 1995. The principle experiment of reducing soil adhesion and scouring soil by nonsmooth surface electro-osmosis. Trans. CSAE 11 (3), 19–23 (in Chinese). Cong, Q., Ren, L.Q., Chen, B.C., Yan, B.Z., 1999. Using characteristics of burrowing animals to reduce soil-tool adhesion. Trans. ASAE 42, 1549–1556. Guo, P., Liu, J., 1995. The effect of magnetized plowshare upon tillage performance. Agric. Res. Afrid Areas 13 (2), 103–109 (in Chinese).
11
Han, G., Zhang, Y., 1991. Measurement and analysis of ploughing resistance on the magnetic plough. Trans. CSAM 22 (3), 25–28 (in Chinese). Jia, X., Ren, L.Q., Chen, B.C., 1996. Characteristics of bionic composite coating reducing adhesion and resistance. Chin. J. Mater. Res. 10 (2), 210–214 (in Chinese). Li, J.Q., Ren, L.Q., Liu, C.Z., Chen, B.C., 1996. A study on the bionic moldboard plow of reducing soil adhesion and plowing resistance. Trans. CSAE 27 (2), 1–4 (in Chinese). Liu, C.Z., Ren, L.Q., Tong, J., Feng, Y.J., 1998. Soil adhesion of UHMWPE and its composite materials. Trans. CSAE 14 (4), 37– 41 (in Chinese). Lu, X.C., Wen, X.Z., Tong, J., Chen, Y., Ren, L.Q., 1996. Wettability, soil adhesion, abrasion and friction wear of PTF (+PPS) + Al2O3 composites. Wear 193, 48–55. Mackson, C.J., 1962. The effect of electro-osmosis on soil to steel sliding friction as influenced by speed, voltage and soil moisture, St. Joseph, Mich. ASAE, ASAE Paper No.62-650 Qaisrani, A.R., Ren, L.Q., Chen, B.C., 1992. Modified and unsmoothed plow surfaces—a means to reduce plowing resistance. Int. Agric. Eng. J. 1 (3), 115–124. Ren, L.Q., Chen, D.X., Hu, J.G., Wang, L., 1990. Initial exploring for mechanism of decreasing resistance and reducing adhesion of the bionic bulldozing plates. Trans. CSAE 6 (2), 13–20 (in Chinese). Ren, L.Q., Cong, Q., Chen, B.C., Wu, L.K., Li, A.Q., Jing, D., 1992. A study on the adhesion reducing character of geometric nonsmooth surface of typical animal. Trans. CSAM 23 (2), 29–35 (in Chinese). Ren, L.Q., Tong, J., Zhang, S.J., Chen, B.C., 1995. Reducing sliding resistance of soil against bulldozing plates by unsmoothed bionics surfaces. J. Terramech. 32, 303–309. Ren, L.Q., Wang, Y.P., Li, J.Q., Tong, J., 1998. Flexible unsmoothed cuticles of soil animals and their characteristics of reducing adhesion and resistance. Chin. Sci. Bull. 43 (2), 166– 1169. Ren, L.Q., Cong, Q., Tong, J., Chen, B.C., 2001a. Reducing adhesion of soil against loading shovel using bionic electro-osmosis method. J. Terramech. 38, 211–219. Ren, L.Q., Tong, J., Li, J.Q., Chen, B.C., 2001b. Soil adhesion and biomimetics of soil-engaging components: a review. J. Agric. Eng. Res. 79 (3), 239–263. Salokhe, V.M., Hoki, M., Sato, K., 1993. Why soil does not stick to enamel coating? J. Terramech. 30 (4), 275–283. Schafer, R.L., Gill, W.R., Reaves, C.A., 1977. Lubrication plows vs. sticky soil. Agric. Eng. 58 (10), 34–38. Sharma, V.K., Drew, L.O., Nelson, G.L., 1977. High frequency vibrational effects on soil-metal friction. Trans. ASAE 20, 46– 51. Shirokov, B.I., 1954. Problem of the utilization of electro-osmosis of soil in plowing, USDA Eng. Translation A888. USDA, Washington, DC. Sun, S.Y., Ren, L.Q., Tong, J., Chen, P., 1993. Study of a shovel bucket with steel-cloth pocket by bionics. Trans. CSAM 24 (4), 18–22 (in Chinese). Tong, J., Ren, L.Q., Chen, Y., Qaisrani, A.R., Chen, B.C., 1994a. Abrasive properties and mechanism of polytetra fluoroethylene
12
L.Q. Ren et al. / Soil & Tillage Research 85 (2006) 1–12
and ultra high molecular weight polyethylene. Tribol. Int. 14, 65–72. Tong, J., Ren, L.Q., Chen, B.C., 1994b. Geometrical morphology, chemical constitution and wettability of body surfaces of soil animals. Int. Agric. Eng. J. 3 (1–2), 59–68. Tong, J., Ren, L.Q., Yan, J.L., Ma, Y.H., Chen, B.C., 1999. Adhesion and abrasion of several materials against soil. Int. Agric. Eng. J. 8 (1), 1–22. Tong, J., Wang, X.Y., Yan, J.L., Han, Z.W., Ren, L.Q., 2000b.Effects of magnetic-field upon soil adhesion and friction, Proceedings of International Agriculture Engineering Conference, 4–7 December, Bangkok, Thailand, pp. 66–72.
Wang, X.L., Ito, N., Kito, K., Garcia, P.P., 1998. Study on use of vibration to reduce soil adhesion. J. Terramech. 35 (2), 87– 101. Wang, Y.P., Ren, L.Q., Li, J.Q., Sun, S.Y., Han, Z.M., 1997. Field test study on flexible bionics technologies of anti-adhesion to dump trucks. Trans. CSAE 13 (3), 128–132 (in Chinese). Yang, X.D., Ren, L.Q., 2001. Experimental study and system model of bionic flexible resistance reduction. Chin. Mech. Eng. 12 (8), 951–953 (in Chinese). Zhu, H., Tan, L., Wu, S., 1992. An experimental study on the ‘‘comet type passage-holes’’ plough of reducing resistance. Trans. CSAM 23 (4), 20–24 (in Chinese).