Tire tread pattern design trigger on the stress distribution over rigid surfaces and soil compaction Luı ´s A.P. Barbosa 1 , Paulo S.G. Magalha ˜es ⇑ University of Campinas, Faculty of Agricultural Engineering, Ca ˆndido Rondon Avenue, 501, Cidade Universita ´ ria, Campinas, Sa ˜o Paulo 13083-875, Brazil Received 16 September 2014; received in revised form 20 December 2014; accepted 24 December 2014 Abstract Studies comparing the structural differences of tires have not qualitatively or quantitatively considered the effects of tread geometry on tire behaviour or the interactions of the tire with the surface. Therefore, to determine the effects of different tire tread patterns on the stress distribution of the tire and soil compaction, we compared the structural behaviours of a high-flotation tractive-tread (TT) tire and a smooth-tread (ST) tire. The experiments were conducted over a rigid and over a deformable surface. The results from the rigid surface shows the influences of the tread pattern and sidewalls is dependent of the loads. Over the deformable surface, the contact area of the TT tire was larger than that of the ST tire. The inflation pressure (IP) was mainly responsible for the load support before the soil reached its maximum deformation. Next, the tread and sidewalls exhibited the same behaviour as observed on the rigid surface. In addi- tion, we observed alterations in the balloon point with the tread geometry and the type of surface due to changes in the contact pressure. With carcass deformation, the volume of the tire was visibly reduced, which indicated that the IP could increase. Ó 2015 ISTVS. Published by Elsevier Ltd. All rights reserved. Keywords: Tire structure; Tread pattern; Structural stiffness; Stress distribution; Soil compaction; Soil bin 1. Introduction More than 50% of the ground area is estimated to be affected by heavy machinery tires in sugarcane fields, even in controlled traffic systems that use real-time kinematic (RTK) auto-guidance systems to prevent passing over the planting rows (Braunbeck and Magalha ˜es, 2010). During the sugarcane production cycle, the narrow track widths of the tractors and harvesters promote at least four passes: two by the harvester and two by the haul-out unit (i.e., 16 passes by different tires with different loads, as shown in Fig. 1)(Braunack and Mcgarry, 2006). The traffic over the crop area that causes the greatest soil damage occurs during harvest due to the high wheel loads of the harvest- ers, which weigh up to 20 tonnes, and the haul-out units, which weigh up to 30 tonnes when fully loaded (Braunack et al., 2006). This activity can lead to soil com- paction in the row and adversely affect crop yields. The effects of compaction are on the physical properties of the soil and the crop response are cumulative, especially in ratoon crops such as sugarcane, a semi perennial crop that is typically grown in cycles of four to seven years (Otto et al., 2011). In recent decades, sugarcane harvesting in Brazil has become more mechanised, and the load capacity of the haul-out unit has increased. In response to these trends, tire http://dx.doi.org/10.1016/j.jterra.2014.12.006 0022-4898/Ó 2015 ISTVS. Published by Elsevier Ltd. All rights reserved. ⇑ Corresponding author. Tel.: +55 19 35211053; fax: +55 19 35211010. E-mail addresses: luis.barbosa@bioetanol.org.br (L.A.P. Barbosa), graziano@feagri.unicamp.br (P.S.G. Magalha ˜es). 1 Present address: Brazilian Bioethanol Science and Technology Labo- ratory (CTBE) – Integrate Brazilian Centre of Research in Energy and Materials (CNPEM), Giuseppe Ma ´ximo Scolfaro Street, 10.000, Polo II de Alta Tecnologia, P.O. Box 6170, Campinas, Sa ˜o Paulo 13083-970, Brazil. www.elsevier.com/locate/jterra Available online at www.sciencedirect.com ScienceDirect Journal of Terramechanics 58 (2015) 27–38 Journal of Terramechanics