The purpose of the present work is to study the influence of humidity effect on the static angle for single particles with diverse sizes on surfaces with differing roughness. The aim is to provide information about the characteristics of cohesive forces between grains and rough surfaces with different grain geometries. The study has an experimental part and it is complemented by Monte Carlo simulations (MCS) and an empirical formulation of the dependence of the critical angle on two important parameters of the problem. The experimental device consists of an inclined surface that allows studying the evolution of the static angle (Ɵs), that is, the angle at which a 50% percent of spheres are put in motion. Relative Humidity (RH) is controlled through hygroscopic salts saturated solutions. Values ​​obtained at different humidity rates are compared. For the MCS, the balance of the moments applied to the particle and necessary for its destabilization are taken into account as a basis for calculating the probabilities for movement. Simulations help to establish a fitting curve that is able to describe the complete set of results by correlating the fitting parameters with the surface roughness and the Bond number for the particles. We determine that for systems with high humidity, the formation of liquid bridges between particles affects the static angle for the onset of movement and this angle decrease as the diameter of the spheres increases. The type of surface has an important role on the static angle values.

本工作的目的是研究湿度影响对具有不同大小的单个粒子在不同粗糙度的表面上的静态角度的影响。目的是提供有关晶粒和具有不同晶粒几何形状的粗糙表面之间的内聚力特性的信息。这项研究具有实验性，并得到了蒙特卡洛模拟（MCS）和临界角对问题两个重要参数的依赖关系的经验公式的补充。实验装置由一个倾斜的表面组成，该表面允许研究静态角（Ɵs）的演变，静态角即50％的球体运动的角度。相对湿度（RH）通过吸湿盐饱和溶液控制。比较在不同湿度下获得的值。对于MCS，考虑了施加到粒子上的力矩平衡及其不稳定所需的平衡，以此作为计算运动概率的基础。模拟通过将拟合参数与粒子的表面粗糙度和邦定数相关联来帮助建立拟合曲线，以描述完整的结果集。我们确定对于高湿度的系统，粒子之间的液桥的形成会影响运动开始时的静态角度，并且该角度随着球体直径的增加而减小。曲面的类型对静态角度值具有重要作用。模拟通过将拟合参数与粒子的表面粗糙度和邦定数相关联来帮助建立拟合曲线，以描述完整的结果集。我们确定对于高湿度的系统，粒子之间的液桥的形成会影响运动开始时的静态角度，并且该角度随着球体直径的增加而减小。曲面的类型对静态角度值具有重要作用。模拟通过将拟合参数与粒子的表面粗糙度和邦定数相关联来帮助建立拟合曲线，以描述完整的结果集。我们确定对于高湿度的系统，粒子之间的液桥的形成会影响运动开始时的静态角度，并且该角度随着球体直径的增加而减小。曲面的类型对静态角度值具有重要作用。粒子之间液体桥的形成会影响运动开始时的静态角度，并且该角度随着球体直径的增加而减小。曲面的类型对静态角度值具有重要作用。粒子之间液体桥的形成会影响运动开始时的静态角度，并且该角度随着球体直径的增加而减小。曲面的类型对静态角度值具有重要作用。