Wear of tillage tools by hard soil particles is a serious concern in the industry since wear is the primary factor that defines an engaging tool's lifespan, stability, and reliability. Many studies have primarily focused on experimental methods to better understand the impact of various parameters on tool wear during tilling operations. Hence, this project focuses on both continuum damage mechanics (CDM) modesl based on thermodynamics for predicting the wear coefficient in tillage tools and experimental validation. The wear process is modeled as sand particle scratching at a prescribed speed and load on the surface of a tillage tool with different hardness, such as heat treated, chromium coated, heat-treated chromium coated, and samples without any treatment. Tillage tool wear is taken as the response (output) variable measured during contact, while operation parameters speed, load, and hardness are taken as input parameters. For C45E4 samples, tests are carried out with a dry sand/rubber wheel abrasion tester, and material loss from the tool surface during scratching is evaluated using the weight loss concept. The design of experiments technique is developed for three factors at four levels. The comparison shows an acceptable agreement in the experimental data and predicted results, which states an error of <20 %. The results also show that heat-treated samples with chromium coating have more abrasive resistance with respect to other samples.

Management of perennial weeds has become increasingly difficult with the reduction of herbicide use. Creeping perennials accumulate reserves in specialized belowground organs from which they regenerate new plants after a disturbance. Through tool selection, tillage operations could be optimized to reduce perennial-weed reserves and limit regeneration. In the present study, the effect of five tools on the fragmentation of the creeping roots of Cirsium arvense (L.) Scop. (Canada thistle), a major perennial weed in arable crops, were analysed. A field trial was set up to measure the lengths of the root fragments left after tillage. Five tools were tested: mouldboard ploughing, rotary harrow, disc harrow, rigid-tine cultivator and goose-foot cultivator. Fragment-length distribution varied according to the tool: rotary harrow left the smallest (3.7 cm on average) and least variable fragment lengths, mouldboard ploughing the longest (12.7 cm) and most variable ones. The other tools produced intermediate-sized fragments (8-10 cm). Based on these results and literature, a model was proposed to predict perennial-weed regeneration probability from storage-organ fragments after one tillage run. The effects of six factors, which were agronomic (tillage tool), environmental (soil conditions and temperature) and biological (storage-organ fragment diameter, maximal belowground-shoot length and pre-tillage storage-organ distribution), were tested through a sensitivity analysis. According to the model, the probability of fragment regeneration success is lower for the rotary harrow than for the mouldboard plough. The most important drivers of fragment regeneration success were the biological traits: fragment diameter and maximal belowground-shoot length per unit fragment biomass. The present model should be complemented to predict the effect of tillage on perennial-weed regrowth and help improving non-chemical weed-management strategies. To achieve this, further research is needed on plant regrowth potential from storage organs and their architecture in the soil.

The tribological process between the tillage tools and the soil is quite complex. Wear on tillage tools changes depending on the material of the tool, opposing material (soil), environment (moisture, temperature), and dynamic factors (stress on sliding surface, sliding time, sliding speed, and sliding type). Chemical composition, microstructure, and mechanical properties of the material from which the tools are made; soil properties such as texture, structure, density, moisture, rock and gravel content; operating conditions such as tillage speed and depth; geometry and surface roughness of the tool, and impact angle with the soil are effective on wear. It is generally accepted that tillage tools go through low-tensioned and two-body abrasive wear. The ratio between the hardness of the tools (Hs) and the hardness of the abrasive soil particles (Ha) determines wear mechanisms. When this ratio is lower than 0.8, microcutting and microplowing mechanisms are dominant. Meanwhile, when the hardness value of the tool's surface is close to or higher than the hardness value of the soil particles, microcracks, fragmentation, and peel-off of the hard phases occur. Therefore, hardness alone may not be sufficient to ensure tribological performance, and hardness and toughness should be balanced since tillage tools are exposed to movements such as impacts.