• Proceedings of the Korean Society For Composite Materials Conference
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• 2001.05a
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• pp.151-154
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• 2001

Shape memory alloy (SMA) has demonstrated its potentials for various smart structure applications. SMA wires undergo a reversible phase transformation from martensite to austenite as temperature increases. This transformation leads to shape recovery and associated recovery strains. If SMA actuators are embedded off the neutral surface and are oriented in arbitrary angles with respect to a beam axis, then the beam bends and twists due to the coupling effects of recovery strains activated. In this study, the bending and twisting of a SMA/Composite beam were controlled by both electric resistive heating and passive elastic tailoring. 3-dimensional finite element formulations were derived and validated to analyze the responses of the SMA/Composite beam. Numerical results show that the shape of the SMA/Composite beam can be controlled by judicious choices of control temperatures, SMA angles, and elastic tailoring.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.05a
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• pp.575-580
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• 2004

In this work, the effect of composite couplings and mass distributions on hub loads of a hingeless rotor in forward flight is investigated. 1'he hingeless composite rotor is idealized as a laminated thin-walled box-beam. The nonclassical effects such as transverse shear and torsion warping are considered in the structural formulation. The nonlinear differential equations of motion are obtained by applying Hamilton's principle. The blade responses and hub loads are calculated using a finite element formulation both in space and time. The aerodynamic forces acting on the blade are calculated using the quasi-steady strip theory. The theory includes the effects of reversed flow and compressibility The magnitude of elastic couplings obtained by MSC/NASTRAN is compared with the classical pitch-flap($\delta$$_{3}$) coupling. It is observed that the elastic couplings and mass distributions of the blade have a substantial effect on the behavior of $N_{b/}$rev hub loads. About 40% hub loads is reduced by tailoring or redistributing the structural properties of the blade.f the blade.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.14 no.8
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• pp.734-740
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• 2004

In this work, the effect of composite couplings and mass distributions on hub loads of a hingeless rotor in forward flight is investigated. The hingeless composite rotor is idealized as a laminated thin-walled box-beam. The nonclassical effects such as transverse shear and torsion warping are considered In the structural formulation. The nonlinear differential equations of motion are obtained by applying Hamilton’s principle. The blade responses and hub loads are calculated using a finite element formulation both in space and time. The aerodynamic forces acting on the blade are calculated using the quasi-steady strip theory. The theory includes the effects of reversed flow and compressibility. The magnitude of elastic couplings obtained by MSC/NASTRAN is compared with the classical pitch-flap($\delta$$_3$) coupling. It Is observed that the elastic couplings and mass distributions of the blade have a substantial effect on the behavior of $N_{b}$ /rev hub loads. About 40％ hub loads is reduced by tailoring or redistributing the structural properties of the blade.e.

• Advances in materials Research
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• v.9 no.2
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• pp.115-131
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• 2020

Limit elastic speed analysis of Al/SiC-based functionally graded annular disk of uniform thickness has been carried out for two cases, namely: metal-rich and ceramic rich. In the present study, the unknown field variable for radial displacement is solved using variational method wherein the solution was obtained by Galerkin's error minimization principle. One of the objectives was to identify the variation of induced stress in a functionally graded disk of uniform thickness at limit elastic speed using modified rule of mixture by comparing the induced von-Mises stress with the yield stress along the disk radius, thereby locating the yield initiation. Furthermore, limit elastic speed has been reported for a combination of varying grading index (n) and aspect ratios (a/b).Results indicate, limit elastic speed increases with an increase in grading indices. In case of an increase in aspect ratio, limit elastic speed increases up to a critical value beyond which it recedes. Also, the objective was to look at the variation of yield stress corresponding to volume fraction variation within the disk which later helps in material tailoring. The study reveals the qualitative variation of yield stress for FG disk with volume fraction, resulting in the possibility of material tailoring from the processing standpoint, in practice.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2013.10a
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• pp.368-369
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• 2013

• Journal of Mechanical Science and Technology
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• v.16 no.5
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• pp.666-675
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• 2002

Piezoelectric Fiber Composites with Interdigitated Electrodes (PFCIDE) were previously introduced as an alternative to monolithic wafers with conventional electrodes for applications of structural actuation. This paper is an investigation into the performance improvement of piezoelectric fiber composite actuators by changing the matrix material. This paper presents a modified micro-electromechanical model and numerical analyses of piezoelectric fiber/piezopolymer matrix composite actuator with interdigitated electrodes (PFPMIDE). Various concepts from different backgrounds including three-dimensional linear elastic and dielectric theories have been incorporated into the present linear piezoelectric model. The rule of mixture and the modified method to calculate effective properties of fiber composites were extended to apply to the PFPMIDE model. The new model was validated when compared with available experimental data and other analytical results. To see the structural responses of a composite plate integrated with the PFPMIDE, three-dimensional finite element formulations were derived. Numerical analyses show that the shape of the graphite/epoxy composite plate with the PFPMIDE may be controlled by judicious choice of voltages, piezoelectric fiber angles, and elastic tailoring of the composite plate.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.32 no.7
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• pp.29-36
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• 2004

In this work, the effect of composite couplings on hub loads of a hingeless rotor in forward flight is investigated. The hingeless composite rotor blade is idealized as a laminated thin-walled box-beam. The nonclassical effects such as transverse shear, torsional warping are considered in the structural formulation. The nonlinear differential equations of motion are obtained by applying Hamilton's principle. The blade response and hub loads are calculated using a finite element formulation in space and time. The aerodynamic forces acting on the blade are calculated by quasi-steady strip theory. The theory includes the effects of reversed flow and compressibility. The magnitude of elastic couplings obtained by MSC/NASTRAN is compared with the classical pitch-flap $({\delta}3)$ or $pitch-lag({\alpha}1)$ coupling. It is found that the elastic couplings have a substantial effect on the behavior of $N_b/rev$ hub loads. Nearly 10 to 40% of hub loads is reduced by appropriately tailoring the fiber orientation angles in the laminae of the composite blade.

• Journal of Chest Surgery
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• v.40 no.7 s.276
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• pp.485-491
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• 2007

Background: Thoracoplasty has become a rarity in current clinical practice, although it has been widely employed for well over a century as a procedure for reducing the capacity of the thoracic cavity. Yet we have perform tailoring thoracoplasty following or concomitant with pulmonary resection in 20 patients. The aim of this study is to evaluate the early and late clinical results and also the significance of tailoring thoracoplasty. Material and Method: From March 1995 to June 2005, modified thoracoplasty following or concomitant with pulmonary resection was performed in 20 patients out of a total of 298 pulmonary resections for closing air leaks and for treating persistent pleural space following pulmonary resections, and to tailor the thoracic cavity to accept a diminished lung volume. Of the 20 patients, 14 patients had tailoring thoracoplasty performed concomitant with pulmonary resection, and the remaining 6 patients also had tailoring thoracoplasty performed following pulmonary resection. The subjects ages ranged from 24 to 77 (mean $59.1{\pm}6.4$) and a male preponderance was noted (17 : 3); the number of left and right surgeries was equal. The preoperative primary underlying diseases were lung cancer in 7 patients, pneumothorax with giant bullous change in 6 patients, bronchiectasis in 2 patients, previous pulmonary tuberculosis associated with aspergilloma in 2 patients, empyema with fibrothorax in 2 patients and multiple lung abscesses & destruction due to previous trauma in 1 patient. The operative methods were apicolysis and subperiosteal removal of the 2nd, 3rd and 4th ribs (the costochondral junction to the posterior portions of the ribs) with preservation of the first rib and compression of the anterior chest via cotton bags and elastic bandages. Result: The mean duration of the air leaks after thoracoplasty was $1.6{\pm}0.2$ days (range: $0{\sim}7$ days) and the mean duration of an indwelling chest tube was 7 days (range: $5{\sim}11$ days); the mean duration of hospitalization was $19.2{\pm}2.8$ days (range: $8{\sim}47$ days). The postoperative complications were wound infection (2) and pneumonia (2); reoperation was done due to bleeding (1) in one patient who underwent concomitant thoracoplasty and there was 1 case of wound infection (1) after postresection thoracoplasty. The mortality was 1 patient in the early phase and 4 patients in the late phase. Conclusion: We conclude that tailoring thoracoplasty may be performed to close anticipated persistent pleural spaces and to accommodate the diminished lung volume with acceptable cosmetic results when this procedure is combined with pulmonary resection in selected patients.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2001.10a
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• pp.53-56
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• 2001

Piezoelectric Fiber Composites with Interdigitated Electrodes (PFCIDE) were previously introduced as an alternative to monolithic wafers with conventional electrodes for applications of structural actuation. This paper is an investigation into the performance improvement of piezoelectric fiber composite actuators by changing the matrix material and actuator shape. This paper presents a modified micro-electromechanical model and numerical analyses of piezoelectric fiber/piezopolymer matrix composite actuator with interdigitated electrodes (PFPMIDE). Numerical analyses show that the shape of the graphite/epoxy composite plate with the PFPMIDE may be controlled by judicious choice of voltages, piezoelectric fiber angles, and elastic tailoring of the composite plate.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2007.10a
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• pp.108-111
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• 2007

It's important to measure quantitative properties about thermal-nano variation conduct of polymer for producing high quality components using NIL process. NanoScale indents can be used ad cells for molecular electronics and drug deliver, slots for integration into nanodevices, and defects for tailoring the structure and properties. In this study, it's to evaluate mechanical characteristic of polymer such as PMMA and PC at high temperature for manufacture of nano/micro size of polymer using indenter at high temperature. At high temperature mechanical properties of polymer have extreme variation. Because heating the polymer, it becomes softer than room temperature. In this case it is especially important to study for mechanical properties of polymer at high temperature.