Unit Block Library of Basic Architectures for Use in Computer-Aided Tissue Engineering of Bone Replacement Scaffolds

Author(s):  
M. Wettergreen ◽  
B. Bucklen ◽  
B. Starly ◽  
E. Yuksel ◽  
W. Sun ◽  
...  

Guided tissue regeneration focuses on the implantation of a scaffold architecture, which acts as a conduit for stimulated tissue growth. Successful scaffolds must fulfill three basic requirements: provide architecture conducive to cell attachment, support adequate fluid perfusion, and provide mechanical stability during healing and degradation. The first two of these concerns have been addressed successfully with standard scaffold fabrication techniques. In instances where load bearing implants are required, such as in treatment of the spine and long bones, application of these normal design criteria is not always feasible. The scaffold may support tissue invasion and fluid perfusion but with insufficient mechanical stability, likely collapsing after implantation as a result of the contradictory nature of the design factors involved. Addressing mechanical stability of a resorbable implant requires specific control over the scaffold design. With design and manufacturing advancements, such as rapid prototyping and other fabrication methods, research has shifted towards the optimization of scaffolds with both global mechanical properties matching native tissue, and micro-structural dimensions tailored to a site-specific defect. While previous research has demonstrated the ability to create architectures of repetitious microstructures and characterize them, the ideal implant is one that would readily be assembled in series or parallel, each location corresponding to specific mechanical and perfusion properties. The goal of this study was to design a library of implantable micro-structures (unit blocks) which may be combined piecewise, and seamlessly integrated, according to their mechanical function. Once a library of micro-structures is created, a material may be selected through interpolation to obtain the desired mechanical properties and porosity. Our study incorporated a linear, isotropic, finite element analysis on a series of various micro-structures to determine their material properties over a wide range of porosities. Furthermore, an analysis of the stress profile throughout the unit blocks was conducted to investigate the effect of the spatial distribution of the building material. Computer Aided Design (CAD) and Finite Element Analysis (FEA) hybridized with manufacturing techniques such as Solid Freeform Fabrication (SFF), is hypothesized to allow for virtual design, characterization, and production of scaffolds optimized for tissue replacement. This procedure will allow a tissue engineering approach to focus solely on the role of architectural selection by combining symmetric scaffold micro-structures in an anti-symmetric or anisotropic manner as needed. The methodology is discussed in the sphere of bone regeneration, and examples of cataloged shapes are presented. Similar principles may apply for other organs as well.

2020 ◽  
Vol 11 (2) ◽  
pp. 8836-8843

Porosity plays a vital role in the development of tissue engineering scaffolds. It influences the biocompatibility performance of the scaffolds by increasing cell proliferation and allowing the transportation of the nutrients, oxygen, and metabolites in the blood rapidly to generate new tissue structure. However, a high amount of porosity can reduce the mechanical properties of the scaffold. Thus, this study aims to determine the geometry of the porous structure of a scaffold which exhibits good mechanical properties while maintaining its porosity at a percentage of more than 80%. Circle and square geometries were used since they are categorized as simple geometry. A unit cell of 12mm x 12mm x 12mm for square shape and pore area of 25π mm2 for circle shape was modeled and simulated by using Finite Element Analysis. The simulation consists of a compression test that determines which geometry exhibits better Young’s Modulus. Since the circle geometry has better Young’s Modulus, the pore size was furthered varied while maintaining the porosity of the scaffold to be above 80%. The same method of the simulation was done on the models. The result shows that the smallest pore size model has the highest Young’s Modulus, which still able to maintain the porosity at 80%.


2011 ◽  
Vol 243-249 ◽  
pp. 1461-1465
Author(s):  
Chuan Min Zhang ◽  
Chao He Chen ◽  
Ye Fan Chen

The paper makes an analysis of the reinforced concrete beams with exterior FRP Shell in Finite Element, and compares it with the test results. The results show that, by means of this model, mechanical properties of reinforced concrete beams with exterior FRP shell can be predicted better. However, the larger the load, the larger deviation between calculated values and test values. Hence, if more accurate calculation is required, issues of contact interface between the reinforced concrete beams and the FRP shell should be taken into consideration.


2021 ◽  
pp. 073168442199086
Author(s):  
Yunfei Qu ◽  
Dian Wang ◽  
Hongye Zhang

The double V-wing honeycomb can be applied in many fields because of its lower mass and higher performance. In this study, the volume, in-plane elastic modulus and unit cell area of the double V-wing honeycomb were analytically derived, which became parts of the theoretical basis of the novel equivalent method. Based on mass, plateau load, in-plane elastic modulus, compression strain and energy absorption of the double V-wing honeycomb, a novel equivalent method mapping relationship between the thickness–width ratio and the basic parameters was established. The various size factor of the equivalent honeycomb model was denoted as n and constructed by the explicit finite element analysis method. The mechanical properties and energy absorption performance for equivalent honeycombs were investigated and compared with hexagonal honeycombs under dynamic impact. Numerical results showed a well coincidence for each honeycomb under dynamic impact before 0.009 s. Honeycombs with the same thickness–width ratio had similar mechanical properties and energy absorption characteristics. The equivalent method was verified by theoretical analysis, finite element analysis and experimental testing. Equivalent honeycombs exceeded the initial honeycomb in performance efficiency. Improvement of performance and weight loss reached 173.9% and 13.3% to the initial honeycomb. The double V-wing honeycomb possessed stronger impact resistance and better load-bearing capacity than the hexagonal honeycomb under impact in this study. The equivalent method could be applied to select the optimum honeycomb based on requirements and improve the efficiency of the double V-wing honeycomb.


2015 ◽  
Vol 83 ◽  
pp. 75-84 ◽  
Author(s):  
S. Haroush ◽  
E. Priel ◽  
D. Moreno ◽  
A. Busiba ◽  
I. Silverman ◽  
...  

2007 ◽  
Vol 546-549 ◽  
pp. 1673-1676 ◽  
Author(s):  
Wei Jia Meng ◽  
Zhan Wen Huang ◽  
Yan Ju Liu ◽  
Xiao Rong Wu ◽  
Yi Sun

Magnetorheological (MR) fluids are suspensions of micron sized ferromagnetic particles dispersed in varying proportions of a variety of non-ferromagnetic fluids. MR fluids exhibit rapid, reversible and significant changes in their rheological (mechanical) properties while subjected to an external magnetic field. In this paper, a double-plate magneto-rheological fluid (MRF) clutch with controllable torque output have been designed. Electromagnetic finite element analysis is used to optimize the design of the clutch by using the commercial FEA software ANSYS.


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