• Proceedings of the Korean Society For Composite Materials Conference
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• 2001.05a
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• pp.244-249
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• 2001

In this paper, we present the simultaneous measurement of the fabricaition strain and temperature during and after cure of unsymmetric composite laminate uising fiber optic sensors. Fiber Bragg grating/extrinsic Fabry-Perot interferometric (FBG/EFPl) hybrid sensors are used to measure those measurands. The characteristic matrix of sensor is analytically derived and measurements can be done without sensor calibration. A wavelength-swept fiber laser is utilized as a light source. FBG/EFPI sensors are embedded in a graphite/epoxy unsymmetric cross-ply composite laminate at different direction and different location. We perform the real time measurement of fabrication strains and temperatures at two points of the composite laminate during cure process in an autoclave. Also, the thermal strains and temperatures of the fabricated laminate are measured in thermal chamber. Through these experiments, we can provide a basis for the efficient smart processing of composite and know the thermal behavior of unsymmetric cross-ply composite laminate.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.6
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• pp.1047-1052
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• 2002

The impact value, the interfacial shear strength, the tensile strength and the fracture strain of Nb/MoSi$_2$laminate composites, which were associated with the interfacial reaction layer, have been investigated. Three types of Nb/MoSi$_2$ laminate composites alternating sintered MoSi$_2$ layers and Nb foils were fabricated as the parameter of hot press temperature. The thickness of interfacial reaction layer of Nb/MoSi$_2$ laminate composites increased with increasing the fabrication temperature. The growth of interfacial reaction layer increased the interfacial shear strength and led to the decrease of impact value in Nb/MoSi$_2$ laminate composites. It was also found that in order to maximize the fracture energy of Nb/MoSi$_2$ laminate composites, interfacial shear strength and the thickness of interfacial reaction layer must be secured appropriately.

• The Journal of Korean Academy of Prosthodontics
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• v.37 no.2
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• pp.143-166
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• 1999

The success of porcelain laminate veneer depends on the bond strength between tooth structure and ceramic restoration and the design of tooth preparation. In particular, incisal coverage and incisal finish line are the two most important factors in long-term fracture resistance. Although the majority of clinicians are practicing incisal coverage and there are various opinions on the geo-metrical ratio between the clinical crown length of the remaining tooth structure and the length of incisal extension in porcelain laminate veneer and the optimal incisal finish lines. scientific evidence still loaves much to be desired. The purpose of this study was to determine the effects of the amounts of incisal coverage and the types of incisal finish line on the stress distribution in maxillary anterior porcelain laminate veneers under two different loading conditions. Three-dimensional finite element models of a maxillary anterior porcelain veneer with differ-ent amounts of incisal coverage ; 0, 1, 2, and 3mm and different incisal finish lines feathered edge, incisal bevel, reverse bevel and lingual chamfer with various amounts of lingual extension were developed. 300N force was applied at the point 0.5mm cervical of the linguoincisal edge in two loading conditions ; A) 125 degrees, B) 132 degrees. Tensile and compressive stress in ceramic and shear stress in the resin cement layer were analyzed using three-dimensional finite element method. The results were as follows : 1. The types of incisal finish line had more influence on the stress distribution in porcelain laminate veneer than the amounts of incisal coverage. 2. In case of no incisal coverage, incisal beveled laminate exhibited more evenly distributed tensile stress than feathered edged laminate. And in case of incisal coverage, reverse beveled laminate and lingual chamfered laminate with 1mm lingual extension exhibited more evenly distributed tensile stress than lingual chamfered laminates with 2mm and 3mm lingual extension. 3. As long as the lingual chamfer goes, less tensile stress was found at the incisal edge, while much more tensile stress was found at the lingual margin area in proportion to the length of lingual extension. 4. Under 125 degree load, tensile stress in porcelain laminate veneer had increased compared with that under 132 degree load and the difference exhibited by the change of the amount of tooth support was larger. 5. The types of incisal finish line and the distance from the incisal finish line to the loading point had more influence on the shear stress distribution in the resin cement layer than the amounts of incisal coverage. In contrast loading condition had little influence.

• Journal of Sensor Science and Technology
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• v.8 no.6
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• pp.440-447
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• 1999

Tensile stress loaded on smart composite structures and thermal stress occurred during the during process of the smart composite materials with embedded optical fiber sensors affect directly the mechanical behavior of the embedded optical fiber sensors within the smart composite structures. Stress distribution within the optical fiber sensors varies with respect to the stacking sequence of the composite laminate and the coating conditions of the optical fibers. The cracks occurred within the composite laminate affect not only the fracture of the composite laminate but also the fracture of the optical fiber sensors embedded within the composite laminate. In this study, firstly, stress distribution of the optical fiber sensors embedded within the composite laminate which is subjected to the tensile and thermal stresses was analyzed using Finite Element Method. And, secondly, the effect of the stacking sequence of the composite laminate and the coating conditions of the optical fiber sensors on the stress distribution of the optical fiber sensors was investigated. Finally, the effect of the crack occurred within the smart composite laminate on the fracture behavior of the optical fiber sensors was also observed through the tensile test.

• Journal of Dental Rehabilitation and Applied Science
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• v.28 no.2
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• pp.191-200
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• 2012

The patients' demand for treatment of unesthetic anterior teeth is steadily growing. Accordingly, several treatment options such as porcelain laminate veneers(PLV) have been proposed to restore the esthetic appearance of the dentition. Porcelain laminate veneers are considered minimally invasive, but they also require removal of sound enamel. One critical step in the porcelain laminate veneer technique is the achievement of sufficient ceramic thickness, and several different strategies for tooth preparation can be found in the literature. This clinical report describes a step-by-step protocols for preparation of these restorations used with the silicone index from diagnostic wax-up and the acrylic resin mock-up. Conservative use of porcelain laminate veneers provided satisfactory esthetic outcomes and preserved sound tooth structure.

• Journal of the Korean Academy of Esthetic Dentistry
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• v.22 no.1
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• pp.4-8
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• 2013

This clinical report shows the importance of selecting appropriate materials in fabricating laminate veneer restorations. Such cases should be carefully selected to ensure bonding durability, providing consistently reliable prognosis.

• Journal of Mechanical Science and Technology
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• v.14 no.8
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• pp.823-829
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• 2000

[ $Nb/MoSi_2$ ]laminate composites have been successfully fabricated by hot pressing in a graphite mould. Lamination of Nb foil and $MoSi_2$ layer showed a sufficient improvement in the absorbed impact energy compared to that of monolithic $MoSi_2$ material. The impact value of $Nb/MoSi_2$ laminate composites obviously is reduced when sintered at temperatures higher than 1523K, even if the composite density contributing to impact load increased along with fabricating temperatures. Impact value of laminate composites was also drastically decreased with the growth of reaction layer after the heat treatment. However, it was effective to increase the pressure at the same sintering temperature for the improvement of the impact value.

• Transactions of the Korean Society of Mechanical Engineers
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• v.15 no.2
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• pp.611-617
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• 1991

Effective stiffness of short fiber composite with a three-dimensional random orientation of fibers is derived theoretically and compared with available experimental data. The laminate analogy and transformed laminate analogy are used for modulus prediction of 2-D and 3-D random composites, respectively. The effective stiffness of random oriented fiber composite can be expressed in terms of longitudinal and transverse stiffnesses of unidirectional composites. The result of transformed laminate analogy is more accurate than other approaches such as, Christensen-Waals equational and Lavengood-Goettler equation, etc. Also the effective properties of random oriented fiber composite can be expressed in terms of fiber and matrix properties such as elastic modulus, shear modulus and Poisson's ratio.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.15 no.1
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• pp.50-60
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• 2016

Laminate composites have a number of excellent characteristics in aspects of strength, stiffness, bending, and buckling. Buckling and postbuckling analysis of laminate composites with layups of [90/0]2s, $[{\pm}45/90/0]s$, $[{\pm}45]2s$ has been carried using the Total Lagrangian nonlinear Newton-Raphson method. The formulation of a geometrically nonlinear composite shell element based on a nonlinear large deformation method is presented. The used element is an eight-node degenerated shell element with six degrees of freedom. Square, circular cylinder, and arch panel laminate geometries were analyzed to verify the effects of the layups on the buckling and postbuckling behavior. The results showed that the effects of laminate layups on bucking and postbuckling behavior and the present formulation showed very good agreement with existing references.

• Composites Research
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• v.14 no.6
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• pp.38-46
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• 2001

In this study, An optimization code that can design microwave absorbing composite laminates is developed, and 3-layered microwave absorbing composite laminates are developed by optimizing the thickness of each layer. The layers are 3 different composite laminates. Many variables including lay-up angles of electromagnetically orthotropic composite layer can be considered in this code. The developed laminate is composed of an impedance matching layer of glass/epoxy fabric laminate, a glass/epoxy fabric laminate layer containing aluminum filler and carbon/epoxy fabric laminate layer. Permittivities of the materials are obtained using a network analyzer and a coaxial air line.