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The TC18 titanium alloy as an aviation landing gear material is famous for its high strength and hardenability. However, under the influence of the harsh service environment, its corrosion resistance is relatively poor. WC–12Co ceramic material is one of the most widely used surface strengthening materials, and the coatings are often produced by high velocity oxygen fuel (HVOF) thermal spraying. In the spraying, the deposition state of particles directly affects the quality and strengthening ability of coating. This study combined the correlation of flow field calculation and impact process of particles, and the particle flight characteristics were analyzed in the three‐dimensional HVOF spraying. The change law for temperature and velocity of particles was explored by changing the spraying distance, oxygen/fuel (O/F) ratio, and particle size. Based on the calculation results of flow field, a three‐dimensional random deposition model of WC–12Co multiparticle was established by the coupled Euler–Lagrange method, and the crystal inhomogeneity was introduced by the Voronoi method. Compared the flattening rate and spreading degree of particles deposition, the evolution law of temperature and stress–strain fields for coating and substrate during the deposition was revealed. [ABSTRACT FROM AUTHOR]

Bone cutting is a complicated surgical operation. It is very important to establish a kind of gradient porous bone model in vitro which is close to human bone for the research of bone cutting. Due to the existing bone cutting researches are based on solid bone model, which is quite different from human bone tissue structure. Therefore, Voronoi method was used to establish a gradient porous bone model similar to real bone tissue to simulate the process of bone drilling in this paper. High temperature and large cutting force during bone drilling can cause serious damage to bone tissue. Urgent research on bone drilling parameters is necessary to reduce cutting temperature and cutting force. The finite element analysis (FEA) of Voronoi bone models with different gradients is carried out, and a Voronoi model which is similar to real bone tissue is obtained and verified by combining the cutting experiment of pig bone. Then orthogonal experiments are designed to optimize the cutting parameters of Voronoi bone model. The range method is used to analyze the influence weights of cutting speed, feed speed and tip angle on cutting temperature and cutting force, and the least square method was used to predict the cutting temperature and cutting force, respectively. The gradient porous bone model constructed by Voronoi method was studied in detail in this paper. This study can provide theoretical guidance for clinical bone drilling surgery, and the prediction model of bone drilling has practical significance.

To improve the efficiency of lightweight optimization for stiffened panels, an efficient dynamic sequential lightweight optimization method based on Voronoi is proposed. Above all, the influences of the mesh size of the stiffened panel skin and strings on load-carrying capacity and the buckling modes of the structure are analyzed based on the parametric model. Furthermore, the dynamic mesh partition is realized according to the height-thickness of the web to balance the accuracy and efficiency of post-buckling analysis. Then, a dynamic sequential approximate optimization incorporating an exploration strategy and an exploitation strategy is proposed. Sampling by Voronoi focuses on global space exploration, while sampling by approximate optimal solution focuses on local exploitation. The parallel sampling with both explorative and exploitative performance is realized by dynamic sampling iteration to convergence, which improved the convergence precision and computational efficiency of the algorithm. Ultimately, the proposed algorithm is applied to the lightweight design of stiffened panels, and compared with the traditional sequential approximation optimization method. The results reveal that the proposed method needs fewer initial sample points and less iteration times to achieve higher optimization accuracy, and obtains an optimized structure with a weight reduction of 32.6% compared with the initial design, which indicates that the proposed method is validated for the prospect of engineering applications. [ABSTRACT FROM AUTHOR]

Bone cutting is a complicated surgical operation. It is very important to establish a kind of gradient porous bone model in vitro which is close to human bone for the research of bone cutting. Due to the existing bone cutting researches are based on solid bone model, which is quite different from human bone tissue structure. Therefore, Voronoi method was used to establish a gradient porous bone model similar to real bone tissue to simulate the process of bone drilling in this paper. High temperature and large cutting force during bone drilling can cause serious damage to bone tissue. Urgent research on bone drilling parameters is necessary to reduce cutting temperature and cutting force. The finite element analysis (FEA) of Voronoi bone models with different gradients is carried out, and a Voronoi model which is similar to real bone tissue is obtained and verified by combining the cutting experiment of pig bone. Then orthogonal experiments are designed to optimize the cutting parameters of Voronoi bone model. The range method is used to analyze the influence weights of cutting speed, feed speed and tip angle on cutting temperature and cutting force, and the least square method was used to predict the cutting temperature and cutting force, respectively. The gradient porous bone model constructed by Voronoi method was studied in detail in this paper. This study can provide theoretical guidance for clinical bone drilling surgery, and the prediction model of bone drilling has practical significance.

In the study of rock mechanics, the variation of rock mechanical characteristics in high-temperature environments is always a major issue. The discrete element method and Voronoi modeling method were used to study the mechanical characteristics and crack evolution of granite specimens subjected to the high temperature and uniaxial compression test in order to study the internal crack evolution process of granite under the influence of high temperatures. Meanwhile, dependable findings were acquired when compared to experimental outcomes. A modified failure criterion was devised, and a Fish function was built to examine the evolution behavior of tensile and shear cracks during uniaxial compression, in order to better understand the evolution process of micro-cracks in granite specimens. Shear contacts occurred first, and the number of shear cracks reached its maximum value earliest, according to the findings. The number of tensile contacts then rapidly grew, whereas the number of shear cracks steadily declined. Furthermore, it was found that when temperature rises, the number of early tensile cracks grows. This study develops a fracture prediction system for rock engineering in high-temperature conditions. [ABSTRACT FROM AUTHOR]