Search

Purpose – The purpose of this study which resulted in this work is to propose an optimization method of sensors distribution for structural impact localization. Design/methodology/approach – This paper presents a multi-objective optimization study of a novel sensors distribution technique, where two optimization objective functions are considered: sensors number and sensors location optimization performance index. In addition, the finite element analysis, the time-frequency transform and the principal component analysis are combined to quantize the above objective functions. The non-dominated sorting genetic algorithm II (NSGA-II) is used to acquire Pareto solutions. Findings – The effectiveness of this method is validated through a prototype laboratory called the piezoelectric intelligent structure where promising results are obtained. Originality/value – An optimization method of this novel sensors distribution technique is built and produced a set of efficiency solutions for the real-world problem of impact localization where two conflicting objectives are involved. [ABSTRACT FROM AUTHOR]

Abrasive water jet (AWJ) is one of the most modern rock drilling methods. Many numerical investigations have been conducted to study the changes occurring the rock microstructure (i.e., near wall rock damage) during the AWJ rock cutting process. Most of the existing models, however, did not consider the breakage of abrasive particles used for AWJ drilling and therefore, could not simulate the actual rock cutting conditions. In this study, we propose an improved AWJ rock cutting model that considers the effects of the shape, the interaction and the fragmentation of abrasive particles. A coupled smoothed particle hydrodynamics (SPH) and finite element method (FEM) method was used for numerical modeling of AWJ rock cutting process. Model predictions were validated by using the experimental results. Differences between the rock cutting characteristic predicted by the existing model and the newly proposed model were compared. The new model was also used to determine the effects of the operational parameters on the AWJ rock cutting performance. Moreover, the influence of the abrasive particles’ breakage on the rock damage characteristics is discussed. The results show that the error between the experimental and the numerical model prediction of the dimensionless AWJ impact diameter is 15.77%. The existing model overestimates the rock damage degree. The rock damage degree tends to increase with an increase in the abrasive particle size (diameter), abrasive jet impact velocity, the impact angle and with a decrease in the abrasive particle mass concentration and rock confining pressure. Compared with the flat surface rock, the damage degree of convex surface rock decreases, while that of concave surface rock increases. The rock damage degree under the condition of no abrasive particle breakage is higher than that of the abrasive particle breakage. [ABSTRACT FROM AUTHOR]