June 1, 2019 by admin 0 Comments

Characterization of the biomechanical properties of canine trachea using a customized 3D-printed apparatus

Authors
Jennifer Sang-jee Lee (a, 1), Jonghyun Park (b, 1), Dong-A Shin (b), Yoon-jong Ryu (a), Hee Chan Kim (c, d, e), Jung Chan Lee (c, d, e), Seong Keun Kwon (a)
Abstract
Objectives The canine trachea is considered to be an excellent preclinical model for tracheal research due to its similar mechanical and dimensional characteristics to the human trachea. However, normative biomechanical properties have yet to be defined and it is one of the main reasons tracheal reconstruction has not succeeded in animal models at large scale. Variation and inaccurate measurement due to a lack of proper apparatus for mechanical tests further prevent determination of normative mechanical data of the trachea. The goal of this study was to overcome these shortcomings by designing the measuring apparatus using 3D-printing technology. Using this apparatus, we determined the normative biomechanical properties of the canine trachea. Methods Whole tracheas were obtained from thirteen mongrel dogs. Biomechanical measurements were performed to determine the radial compressive strength and tensile strength of the intact trachea, and the elastic modulus of the tracheal cartilage. Results Structural parameter data indicated the canine trachea to have inner-diameters similar to those of the human trachea and other widely used animal models. The compressive strength was 4.24 N while the tensile strength was 29.96 N. The elastic modulus of the cartilage portion of the trachea was 1.58 N without showing a significant difference in value based on the location of the trachea. Conclusions This study delineates a comprehensive and foundational characterization of the biomechanical properties of both the intact and cartilage portion of the canine trachea. The parameters were in agreement with those of the human trachea, confirming the canine trachea to be an excellent preclinical model for tracheal research.

October 17, 2016 by admin 0 Comments

The effects of moisture and temperature on the mechanical properties of additive manufacturing components: fused deposition modeling

Authors
Eunseob Kim, Yong-Jun Shin, Sung-Hoon Ahn
Abstract
Purpose This paper aims to investigate the water absorption behaviors and mechanical properties, according to water absorption and temperature, of components fabricated by fused deposition modeling (FDM) and injection molding. The mechanical properties of FDM and injection molded parts were studied under several environmental conditions. Design/methodology/approach FDM components can be used as load-carrying elements under a range of moisture and temperature conditions. FDM parts show anisotropic mechanical properties according to build orientation. Components were fabricated from acrylonitrile-butadiene-styrene in three different orientations. The mechanical properties of parts fabricated by FDM were compared to injection molded components made from the same material. Water absorption tests were conducted in distilled water between 20 and 60°C to identify the maximum water absorption rate. Both moisture and temperature were considered as environmental variables in the tensile tests, which were conducted under various conditions to measure the effects on mechanical properties. Findings The water absorption behavior of FDM components obeyed Fickian diffusion theory, irrespective of the temperature. High temperatures accelerated the diffusion rate, although the maximum water absorption rate was not affected. The tensile strength of FDM parts under dry, room temperature conditions, was approximately 26-56 per cent that of injection molded parts, depending on build orientation. Increased temperature and water absorption had a more significant effect on FDM parts than injection molded components. The tensile strength was decreased by 67-71 per cent in hot, wet environments compared with dry, room temperature conditions. Originality/value The water absorption behavior of FDM components was investigated. The quantitative effects of temperature and moisture on tensile strength, modulus and strain were also measured. These results will contribute to the design of FDM parts for use under various environmental conditions.