RIDE VIBRATION AND COMPACTION DYNAMICS OF VIBRATORY SOIL COMPACTORS

This study explores the ride dynamics of typical North-American vibratory soil compactors via analytical and experimental methods. In-plane ride dynamic models of the vehicle are formulated to evaluate ride vibration responses of the vehicle in the transit mode on undeformable terrain surfaces with the roller vibrator off. An in-plane dynamic model is also formulated to study the compaction mode dynamics at lower speeds on elasto-plastic soil subject to roller induced vibration. Field measurements were conducted to characterize the ride vibration environments during the two modes of operations. The ride dynamic models of the soil compactor are thus analyzed to study its whole-body vibration environment while operating on undeformable random terrain surfaces. The modeling of the equipment in compaction mode of operation, however, gives insight over the efficiency of the compactor as a tool aimed to perform compaction of soil layers by plastic deformation (compression). The ride vibration environment of the vehicle and its compaction capability is subsequently assessed using the ISO-2631-1 (1997) guidelines and commonly accepted compaction criteria, respectively. The validity of the proposed model is demonstrated by comparing the model responses with the measured data. Comprehensive parametric analyses were subsequently performed to study the influences of variations in various design and operating parameters on the ride quality and the compaction efficiency of the mobile equipment. The results of the study are utilized to propose desirable design and operating parameters of the vibratory soil compactor for enhancement of its ride vibration environment and compaction performance

Modelling Tire Tractive Performance at Lower Inflation Pressures

When it comes to tractors used in field work, large amounts of energy are lost at the tire/soil interface. The Brixius equations are a set of equations designed to predict tractive performance. These equations were developed based on data acquired in the 1970‘s and 1980‘s, and may not accurately represent today‘s tire and tractor technologies nor accurately scale across a range of inflation pressures. Especially, they may underestimate the benefit of very low pressure conceivable during field work when the tractor is equipped with Central Tire Inflation Systems (CTIS). A two-wheel drive (2WD) tire test tractor fitted with instrumentation was used to pull a load tractor equipped with a ground engaging implement to analyze the ability of the Brixius equations to predict the net tractive performance of radial tires across changes in inflation pressure, soil condition, and ballasting. The drawbar pull produced by the tractor was measured by a load cell, while the torque transmitted through the axle of the tractor was determined using strain gauges. After analyzing the data collected, it was determined that the Brixius equations did not fully account for changes in tire pressure when predicting net tractive force. Similarly, changes in soil conditions were also not completely captured by the Brixius equation.This presentation is from Hamm, Austin R., Ario Kordestani, Brian L. Steward, and Stuart J. Birrell. "Modelling Tire Tractive Performance at Lower Inflation Pressures." 2023 ASABE Annual International Meeting, Paper No. 2300141, pages 1-13. American Society of Agricultural and Biological Engineers, 2023. doi: 10.13031/aim.202300141. Posted with permission