scholarly journals The effects of the printing direction and UV artificial degradation on the mechanical properties using AM PolyJet technology

Author(s):  
Martin Matušú ◽  
David Blaha ◽  
Petr David ◽  
Zdeněk Padovec ◽  
Pavel Růžička ◽  
...  

This study addresses differences in the material properties due to the influence of the printing direction, UV degradation and the use of differently coloured materials. The specimens were manufactured employing PolyJet technology from the Vero material (VeroBlue, VeroYellow, VeroMagenta). Subsequently, the specimens were subjected to tension and compression testing. Ageing is simulated via the exposure of the specimens to solar UVA and UVB for 15 and 30 days (the calculated daylight UV exposure for half a year and a whole year, respectively). The differences in the material properties were also determined according to the types of material. The results were then subjected to a statistical analysis.

2011 ◽  
Vol 94-96 ◽  
pp. 1115-1119
Author(s):  
Xue Ying Yang ◽  
Yuan Mei Li ◽  
Wen Tao Dong ◽  
Bo Zhang

The equation to determine the neutral axis of concrete filled steel tube(CFST) component with round section is presented in this paper. The geometric equation, physical equation and static equilibrium equation of CFST are analyzed to determine its section neutral axis. The compressed mechanical properties of CFST component are analyzed with the concrete material properties divided into tension and compression parts.Comparing the numerical results with the experimental results it can be verified that the equation to determine the neutral axis of CFST component with round section is useful to solve the problems that the tension and compression material properties of concrete are different.


2015 ◽  
Vol 801 ◽  
pp. 273-277
Author(s):  
Karla Noemy Kun ◽  
Lorand Kun ◽  
Ramona Nagy ◽  
Karoly Menyhardt ◽  
Dana Silaghi-Perju ◽  
...  

This work presents an experimental program to determine the mechanical properties of cancellous bone in the femoral head as a function of location. To achieve this several specimens of cancellous bone of approximately 10 mm height and 10 mm diameter were obtained from one human femoral head, starting the sampling from its main loading compressive direction. All specimens underwent compression testing in order to determine the mechanical properties of each specimen and thus a properties map of the cancellous bone in the femoral head was obtained. Based on the results a parametric file with material properties was created in order to be used by professionals in finite element analysis programs.


2003 ◽  
Vol 774 ◽  
Author(s):  
Janice L. McKenzie ◽  
Michael C. Waid ◽  
Riyi Shi ◽  
Thomas J. Webster

AbstractCarbon nanofibers possess excellent conductivity properties, which may be beneficial in the design of more effective neural prostheses, however, limited evidence on their cytocompatibility properties exists. The objective of the present in vitro study was to determine cytocompatibility and material properties of formulations containing carbon nanofibers to predict the gliotic scar tissue response. Poly-carbonate urethane was combined with carbon nanofibers in varying weight percentages to provide a supportive matrix with beneficial bulk electrical and mechanical properties. The substrates were tested for mechanical properties and conductivity. Astrocytes (glial scar tissue-forming cells) were seeded onto the substrates for adhesion. Results provided the first evidence that astrocytes preferentially adhered to the composite material that contained the lowest weight percentage of carbon nanofibers. Positive interactions with neurons, and, at the same time, limited astrocyte functions leading to decreased gliotic scar tissue formation are essential for increased neuronal implant efficacy.


2018 ◽  
Vol 84 (12) ◽  
pp. 61-67
Author(s):  
V. A. Eryshev

The mechanical properties of a complex composite material formed by steel and hardened concrete, are studied. A technique of operative quality control of new credible concrete and reinforcement, both in laboratory and field conditions is developed for determination of the strength and strain characteristics of materials, as well as cohesion forces determining their joint operation under load. The design of the mobile unit is presented. The unit provides a possibility of changing the direction of loading and testing the reinforced element of the given shape both for tension and compression. Moreover, the nomenclature of testing equipment and the number of molds for manufacturing concrete samples substantially decrease. Using the values of forcing resulting in concrete cracking when the joint work of concrete and reinforcement is disrupted the values of the inherent stresses and strains attributed to the concrete shrinkage are determined. An analytical relationship between the forces and deformations of the reinforced concrete sample with central reinforcement is derived for axial tension and compression, with allowance for strains and stresses in the reinforcement and concrete resulted from concrete shrinkage. The results of experimental studies are presented, including tension diagrams and diagrams of developing axial deformations with an increase in the load under the central loading of the reinforced elements. A methodology of accounting for stresses and deformations resulted from concrete shrinkage is developed. The applicability of the derived analytical relationships between stresses and deformations on the material diagrams to calculations of the reinforced concrete structures in the framework of the deformation model is estimated.


Author(s):  
M D Stanciu ◽  
H D Teodorescu ◽  
M Trandafir ◽  
V Guţăş ◽  
A Savin

Polymers ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 822
Author(s):  
Jy-Jiunn Tzeng ◽  
Tzu-Sen Yang ◽  
Wei-Fang Lee ◽  
Hsuan Chen ◽  
Hung-Ming Chang

In this study, five urethane acrylates (UAs), namely aliphatic urethane hexa-acrylate (87A), aromatic urethane hexa-acrylate (88A), aliphatic UA (588), aliphatic urethane triacrylate diluted in 15% HDD (594), and high-functional aliphatic UA (5812), were selected to formulate five UA-based photopolymer resins for digital light processing (DLP)-based 3D printing. Each UA (40 wt%) was added and blended homogenously with ethoxylated pentaerythritol tetraacrylate (40 wt%), isobornyl acrylate (12 wt%), diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide (3 wt%), and a pink acrylic (5 wt%). Each UA-based resin specimen was designed using CAD software and fabricated using a DLP 3D printer to specific dimensions. Characteristics, mechanical properties, and cytotoxicity levels of these designed UA-based resins were investigated and compared with a commercial 3D printing denture base acrylic resin (BB base) control group at different UV exposure times. Shore hardness-measurement data and MTT assays were analyzed using a one-way analysis of variance with Bonferroni’s post hoc test, whereas viscosity, maximum strength, and modulus were analyzed using the Kruskal–Wallis test (α = 0.05). UA-based photopolymer resins with tunable mechanical properties were successfully prepared by replacing the UA materials and the UV exposure times. After 15 min of UV exposure, the 5812 and 594 groups exhibited higher viscosities, whereas the 88A and 87A groups exhibited lower viscosities compared with the BB base group. Maximum flexural strength, flexural modulus, and Shore hardness values also revealed significant differences among materials (p < 0.001). Based on MTT assay results, the UA-based photopolymer resins were nontoxic. In the present study, mechanical properties of the designed photopolymer resins could be adjusted by changing the UA or UV exposure time, suggesting that aliphatic urethane acrylate has good potential for use in the design of printable resins for DLP-type 3D printing in dental applications.


2012 ◽  
Vol 532-533 ◽  
pp. 234-237
Author(s):  
Wei Lai Chen ◽  
Ding Hong Yi ◽  
Jian Fu Zhang

The purpose of this paper is to study the effect of high temperature in injection molding process on mechanical properties of the warp-knitted and nonwoven composite fabrics (WNC)used in car interior. Tensile, tearing and peeling properties of WNC fabrics were tested after heat treatment under120, 140,160,180°C respectively. It was found that, after 140°C heat treatment, the breaking and tearing value of these WNC fabrics are lower than others. The results of this study show that this phenomenon is due to the material properties of fabrics. These high temperatures have no much effect on peeling properties of these WNC fabrics. It is concluded that in order to preserve the mechanical properties of these WNC fabrics, the temperature near 140°C should be avoided possibly during injection molding process.


2016 ◽  
Vol 17 (4) ◽  
pp. 242-253 ◽  
Author(s):  
Stephen J. Foster ◽  
Mark G. Stewart ◽  
Mindy Loo ◽  
Mukshed Ahammed ◽  
Vute Sirivivatnanon

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