Evaluating the viscoelastic properties of glass above transition temperature for numerical modeling of lens molding process

2007 ◽  
Author(s):  
Tianfeng Zhou ◽  
Jiwang Yan ◽  
Tsunemoto Kuriyagawa
Keyword(s):  
Numerical Modeling ◽  
Transition Temperature ◽  
Viscoelastic Properties ◽  
Molding Process ◽  
Lens Molding

Application of Orthogonal Test in Numerical Simulation of Glass Lens Molding

2012 ◽  
Vol 497 ◽  
pp. 245-249
Author(s):  
Dao Cheng Zhang ◽  
Ke Jun Zhu ◽  
Yong Jian Zhu ◽  
Shao Hui Yin ◽  
Jian Wu Yu
Keyword(s):  
Process Parameters ◽  
Orthogonal Experiment ◽  
Fem Simulation ◽  
Orthogonal Test ◽  
Test Method ◽  
Testing Time ◽  
Molding Process ◽  
Glass Lens ◽  
Lens Molding ◽  
Process Factors

Glass lens molding is a high-volume fabrication method for producing optical components. In this paper, combined with the orthogonal test method and finite element method (FEM) simulation, the coupled thermo-mechanical analysis was carried out to analyze the key process factors. In order to reduce the testing time, an orthogonal test with three sets of level factors and three parameters is conducted to obtain the optimal molding process parameters. The result shows that the most significant parameter is molding velocity, the other effect parameters are molding temperature and friction coefficient. According to the previous analysis of orthogonal experiment, it is shown that the best optimal finishing process parameters were A2B1C1.

Thermal Stability of Al2O3 Coated Low Transition Temperature Glass

2010 ◽  
Vol 297-301 ◽  
pp. 875-880 ◽  
Author(s):  
Kung Jeng Ma ◽  
His Hsin Chien ◽  
S. Prabhakar Vattikuti ◽  
Chien Huang Kuo ◽  
Cheng Bang Huo ◽  
...  
Keyword(s):  
Stainless Steel ◽  
High Temperature ◽  
Transition Temperature ◽  
Heating Temperature ◽  
Steel Substrate ◽  
Sol Gel ◽  
Contact Angles ◽  
Reaction Products ◽  
Molding Process ◽  
Coated Glass

There are growing varieties of glasses available on the market for the manufacture of molded optical lenses. A glass with a low transition temperature (Tg) has the advantage of extending the service life of molding dies. However, most of the low Tg glasses have a high content of alkali metal oxides and tend to induce severe glass sticking problems. This has made the molding process of these kinds of glasses very difficult indeed. The low Tg glasses normally demonstrate poor chemical durability and scratch resistance. As a result, the yields of fabricating the glass-preforms are frequently rather low. This research tried depositing a very thin layer of aluminum oxide on various glass-preforms by a water based sol-gel process. A high temperature glass wetting experiment was carried out to investigate the high temperature interfacial reaction between the coated glass gobs and stainless steel substrate. It was found that when the uncoated glass-preforms were brought into contact with stainless steel, the contact angle decreased with increasing heating temperature and duration. Owing to the severe interfacial chemical reaction, the originally transparent glass gradually turned translucent. In the case of Al2O3 coated glass-preforms, the variation of the contact angles was very limited, which presented no sticking and no wetting behavior. No reaction products could be detected on the contact area after the wetting test. The optical transmission of those lenses molded from the coated glass-preforms exhibited no or very little changes after the molding process.

scholarly journals Evaluation of viscoelastic properties, hardness, and glass transition temperature of soft denture liners and tissue conditioner

Odontology ◽  
2019 ◽  
Vol 108 (3) ◽  
pp. 366-375 ◽  
Author(s):  
Yukiro Kitagawa ◽  
Kazuhiro Yoshida ◽  
Kazuma Takase ◽  
Alireza Valanezhad ◽  
Ikuya Watanabe ◽  
...  
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Viscoelastic Properties ◽  
Denture Liners ◽  
Tissue Conditioner

Viscoelastic Properties of Multi Walled Carbon Nanotube/Epoxy Composites at the Different Nanotube Content

2011 ◽  
Vol 13 ◽  
pp. 33-39 ◽  
Author(s):  
Arash Montazeri ◽  
Alireza Khavandi ◽  
Jafar Javadpour ◽  
Abbas Tcharkhtchi
Keyword(s):  
Carbon Nanotube ◽  
Viscoelastic Properties ◽  
Epoxy Composite ◽  
Viscoelastic Behavior ◽  
Molding Process ◽  
Cole Diagram ◽  
Multi Walled Carbon Nanotube ◽  
Viscoelastic Modeling ◽  
Good Agreement ◽  
Properties Of Composites

The viscoelastic properties of composites multi walled carbon nanotube / epoxy at different weight fractions (0.1, 0.5 and 1wt %) were evaluated by performing dynamic mechanical thermal analysis (DMTA) test. The MWCNT/ epoxy composite were fabricated by sonication and a cast molding process. The results showed that addition of nanotubes to epoxy had a significant effect on the viscoelastic properties. However, the use of 0.5wt% increased the viscoelastic properties more significantly. Concerning viscoelastic modeling, the COLE-COLE diagram has been plotted by the result of DMTA tests. These results show a good agreement between the Perez model and the viscoelastic behavior of the composite.

Effect of layering pattern and fiber hybridization on viscoelastic properties of PALF/COIR hybrid epoxy composites

2021 ◽  
Vol 15 (1) ◽  
pp. 7894-7906
Author(s):  
Mohit Mittal ◽  
Rajiv Chaudhary
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Viscoelastic Properties ◽  
Volume Fraction ◽  
Interfacial Region ◽  
Damping Factor ◽  
Structural Applications ◽  
Fiber Matrix ◽  
Hybrid Biocomposite

To design and develop a hybrid biocomposite material for structural applications, it becomes necessary to determine the optimum fibers layering pattern. Therefore, in this research work, the different layered hybrid biocomposite boards i.e. bilayer pineapple/coir (P/C), trilayer (PCP, CPC), and intimately mixed (IM) were developed and characterized for viscoelastic properties. The composites were made by hand lay-up method, keeping the volume ratio of PALF and COIR 1:1 and the total fiber volume fraction is 0.40 volume of composite. Dynamic mechanical thermal analysis test was employed to characterize the viscoelastic behavior in terms of storage modulus, loss modulus, loss damping factor, and the glass transition temperature. Amongst all the different layered hybrid composites, the trilayer CPC has lowest value (0.635) of effectiveness coefficient with highest stiffness and activation energy (40.54 kJ/mole). It confirms the better fiber-matrix interaction at the interfacial region. The glass transition temperature of CF-EP and PF-EP was increased by 8.74% and 13.15% respectively by the synergistic hybridization of cellulosic fibers. The PCP layered composite possesses lowest value of phase transition energy (9.17 kJ/mole) and this was because of the poor fiber-matrix interfacial adhesion.

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