scholarly journals A New Approach for Irregular Porous Structure Modeling based on Centroidal Voronoi Tessellation and B-Spline

Author(s):  
Yaohui You
Author(s):  
Lihao Tian ◽  
Lin Lu ◽  
Weikai Chen ◽  
Yang Xia ◽  
Charlie C. L. Wang ◽  
...  

Micromachines ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 664
Author(s):  
Haiyuan Zhao ◽  
Yafeng Han ◽  
Chen Pan ◽  
Ding Yang ◽  
Haotian Wang ◽  
...  

In order to obtain scaffold that can meet the therapeutic effect, researchers have carried out research on irregular porous structures. However, there are deficiencies in the design method of accurately controlling the apparent elastic modulus of the structure at present. Natural bone has a gradient porous structure. However, there are few studies on the mechanical property advantages of gradient bionic bone scaffold. In this paper, an improved method based on Voronoi-tessellation is proposed. The method can get controllable gradient scaffolds to fit the modulus of natural bone, and accurately control the apparent elastic modulus of porous structure, which is conducive to improving the stress shielding. To verify the designed structure can be fabricated by additive manufacturing, several designed models are obtained by SLM and EBM. Through finite element analysis (FEA), it is verified that the irregular porous structure based on Voronoi-tessellation is more stable than the traditional regular porous structure of the same structure volume, the same pore number and the same material. Furthermore, it is verified that the gradient irregular structure has a better stability than the non-gradient structure. An experiment is conducted successfully to verify the stability performance got by FEA. In addition, a dynamic impact FEA is also performed to simulate impact resistance. The result shows that the impact resistance of the regular porous structure, the irregular porous structure and the gradient irregular porous structure becomes better in turn. The mechanical property verification provides a theoretical basis for the structural design of gradient irregular porous bone tissue engineering scaffolds.


Author(s):  
Fengtao Fan ◽  
Fuhua (Frank) Cheng ◽  
Conglin Huang ◽  
Yong Li ◽  
Jianzhong Wang ◽  
...  

Author(s):  
Zezhong C. Chen ◽  
Xujing Yang

Extensive research on G1 biarcs fitting to free-form curves (i.e., Bezier, B-spline, and NURBS curves) has been conducted in the past decades for various purposes, including CNC contouring to make smooth, accurate profile features such as pockets, islands, and sides. However, all the proposed approaches only focused on the approximation errors and the biarc number, not on the radius of the individual fitting arc; so it could be smaller than the cutting tool, which would cause gouging during machining. This work, based on the tool radius pre-determined by the minimum size of the concavities of the design profile, proposes a new approach to approximating the profile with a G1 biarc curve in order to make smooth, accurate, and non-gouged profile features using CNC contouring. The significant new contribution of this work is a new mechanism that ensures all the concave arcs of the fitting curve are larger than the pre-determined tool and the fitting errors meet the specified tolerance. This approach can promote the use of G1 biarc tool paths in the manufacturing industry to make high precision profile features.


Author(s):  
J. Xia ◽  
Q. J. Ge

Abstract This paper develops methods for the exact analysis and representation of the swept volume of a circular cylinder undergoing rational Bézier and B-spline motions. Instead of following the traditional approach of analyzing the point trajectory of an object motion for swept volume analysis, this paper seeks to develop a new approach to swept volume analysis by studying the plane trajectory of a rational motion. It seeks to bring together recent work in swept volume analysis, plane representation of developable surfaces, as well as computer aided synthesis of freeform rational motions. The results have applications in design and approximation of freeforms surfaces as well as tool path planning for 5-axis machining of freeform surfaces.


2019 ◽  
Vol 968 ◽  
pp. 68-75
Author(s):  
Valeriy Vyrovoy ◽  
Viacheslav Bachynckyi ◽  
Nadia Antoniuk

The paper presents the development of optimum structures and the production of polymeric coatings technology which can absorb aggressive substances. The studies of coatings penetrating into the film are presented due to the organization of their capillary-cellular structure by introducing special fillers. A new approach to solve the problem of protecting the environment, people, buildings and structures from the effects of aggressive substances has been proposed. The essence of the method consists in the preventive deposition on the surfaces of construction objects of porous coatings that can irreversibly absorb aggressive substances. Based on theoretical and experimental studies, porous coatings have been developed that are capable of accumulating in their volume aggressive substances, as well as certain principles of providing the coating with the necessary capillary-porous structure. The mechanism of creating a capillary-cellular structure of a polymer coating based on nitrocellulose are substantiated.


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