• Title/Summary/Keyword: Beam configuration

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Design Optimization of Structure-born Noise of Automobile (자동차 소음/진동의 최적 설계)

  • 왕세명;최경국;하리쿨카니
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 1996.10a
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    • pp.104-109
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    • 1996
  • Continuum element sensitivity analysis (CONTESA) and system optimization (SYSOPT) for Noise, Vibration, and Harshness (NVH) have been developed and applied to automobile structures for sizing, topology, and configuration design using Mindlin plate and Timoshenko beam theories. The topology optimization has been developed using the density approach, sequential linear programming, and the adjoint variable method. CONTESA has been tested using various vehicle models. Optimized vehicles using CONTESA and SYSOPT are manufactured to validate the simulation-based design methodology.

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Evaluation the behavior of pre-fabricated moment connection with a new geometry of pyramidal end block under monotonic and cyclic loadings

  • Kazemi, Seyed Morteza;Sohrabi, Mohammad Reza;Kazemi, Hasan Haji
    • Steel and Composite Structures
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    • v.29 no.3
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    • pp.391-404
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    • 2018
  • Researchers have been long studying new building implementation methods to improve the quality of construction, reduce the time of assembly, and increase productivity. One of these methods is the use of modular pre-fabricated structural forms that are composed of a beam, column, short column, pyramidal end block, and connection plates. In this study, a new geometry for the pyramidal end block was proposed that helps facilitate the assembly procedure. Since the proposed configuration affects the performance of this form of connection, its behavior was evaluated using finite element method. For this purpose, the connection was modeled in ABAQUS and then validated by comparing the outputs with experimental results. The research proceeded through analyzing 16 specimens under monotonic and cyclic loading. The results indicated that using the pyramidal end block not only makes the assembly process easier but also reduces the out-of-plane displacement of the short column webs and the vertical displacement of beam end. By choosing appropriate section properties for column and beam, the connection can bear a rotation up to 0.01 radians within its inelastic region and a total of 0.04 radians without any significant reduction in its bearing capacity.

Thermal Stability Analysis of a Flexible Beam Spacecraft Appendage (위성체 유연 보 구조물의 열 안정성 해석)

  • 윤일성;송오섭
    • Composites Research
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    • v.15 no.3
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    • pp.18-29
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    • 2002
  • The bending vibration and thermal flutter instability of spacecraft booms modeled as circular thin-walled beams of closed cross-section and subjected to thermal radiation loading is investigated in this paper. The thin-walled beam model incorporates a number of nonclassical effects of transverse shear, primary and secondary warping, rotary inertia and anisotropy of constituent materials. Thermally induced vibration response characteristics of a composite thin walled beam exhibiting the circumferantially uniform system(CUS) configuration are exploited in connection with the structural flapwise bending-lagwise bending coupling resulting from directional properties of fiber reinforced composite materials and from ply stacking sequence. The numerical simulations display deflection time-history as a function of the ply-angle of fibers of the composite materials, damping factor, incident angle of solar heat flux, as well as the boundary of the thermal flutter instability domain. The adaptive control are provided by a system of piezoelectric devices whose sensing and actuating functions are combined and that are bonded or embedded into the host structure.

Development of Projection Scanbeam-SLA using Liquid Crystal Display and Visible Light Emitting Diode (LCD와 가시광선 LED를 사용한 전사방식의 Scanbeam-SLA 개발)

  • Yoon, Su Hyun;Park, In Baek;Kim, Min Sub;Jo, Kwang Ho;Lee, Seok Hee
    • Journal of the Korean Society for Precision Engineering
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    • v.30 no.3
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    • pp.340-348
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    • 2013
  • In Projection Stereolithography Apparatus (PSLA), Digital Micromirror Device (DMD) and Liquid Crystal Display (LCD) are used as a beam pattern generator. The DMD shows high resolution, but it is mostly applied in micro stereolithography due to high cost and fabricable area. In LCD, the size of pattern beam is freely controlled due to various panel sizes. The LCD, however, has some limitations such as short life time by the high power light source, non-uniform light intensity of pattern beam and low transmittance of UV-light. To solve these problems in LCD-based PSLA, a Scanbeam-SLA with LCD of 19 inches and visible LED-array is developed. In this system, the light module works like a scanner for uniform illumination. The system configuration, working principle and fabrication examples are addressed in this study.

Post-buckling analysis of Timoshenko beams with temperature-dependent physical properties under uniform thermal loading

  • Akbas, Seref Doguscan;Kocaturk, Turgut
    • Structural Engineering and Mechanics
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    • v.44 no.1
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    • pp.109-125
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    • 2012
  • Post-buckling behavior of Timoshenko beams subjected to uniform temperature rising with temperature dependent physical properties are studied in this paper by using the total Lagrangian Timoshenko beam element approximation. The beam is clamped at both ends. In the case of beams with immovable ends, temperature rise causes compressible forces end therefore buckling and post-buckling phenomena occurs. It is known that post-buckling problems are geometrically nonlinear problems. Also, the material properties (Young's modulus, coefficient of thermal expansion, yield stress) are temperature dependent: That is the coefficients of the governing equations are not constant in this study. This situation suggests the physical nonlinearity of the problem. Hence, the considered problem is both geometrically and physically nonlinear. The considered highly non-linear problem is solved considering full geometric non-linearity by using incremental displacement-based finite element method in conjunction with Newton-Raphson iteration method. The beams considered in numerical examples are made of Austenitic Stainless Steel (316). The convergence studies are made. In this study, the difference between temperature dependent and independent physical properties are investigated in detail in post-buckling case. The relationships between deflections, thermal post-buckling configuration, critical buckling temperature, maximum stresses of the beams and temperature rising are illustrated in detail in post-buckling case.

Fizeau interferometry using angled end-face optical fiber source (경사 단면 광섬유 광원을 이용한 피조 간섭계)

  • 김학용;김병창;김승우
    • Korean Journal of Optics and Photonics
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    • v.12 no.4
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    • pp.334-338
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    • 2001
  • A Fizeau interferometer without beam splitter was constructed. Single-mode optical fiber was used as a spherical wave source and the face of fiber end was polished and coated to be a reflecting surface. The reflecting surface was angled so that interference fringe could be detected by CCD camera. Beam splitter in front of a spherical wave source could distort the wave front and that was one of the component error sources. With the proposed configuration there was no need to place beam splitter in the system. Improvement of phase measuring accuracy was evaluated quantitatively by comparing the result of this setup with that of a conventional Fizeau interferometer. Wave front of the angled end-face optical fiber source was also measured to verify its sphericity by PS/PDI (Phase Shifting/Point Diffraction Interferometer). The principle of this technique was presented and the experimental results and its applications were discussed. ussed.

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Endodontic management of a maxillary lateral incisor with dens invaginatus and external root irregularity using cone-beam computed tomography

  • Lim, Young-Jun;Nam, Sook-Hyun;Jung, Sung-Ho;Shin, Dong-Ryul;Shin, Su-Jung;Min, Kyung-San
    • Restorative Dentistry and Endodontics
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    • v.37 no.1
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    • pp.50-53
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    • 2012
  • Cone-beam computed tomography (CBCT) is a useful diagnostic tool for identification of both internal and external root configurations. This case report describes the endodontic management of a lateral incisor with both dens invaginatus and external root irregularity by using CBCT. Nonsurgical endodontic retreatment was performed on the lateral incisor with dens invaginatus. A perforation through the dens invaginatus and external concavity was repaired using mineral trioxide aggregate. After 18 mon of follow-up, there were no clinical symptoms. Recall radiographs appeared normal and showed healing of the periapical pathosis. The understanding of both internal root canal configuration and external root irregularity using CBCT can ensure predictable and successful results.

Role of cone-beam computed tomography in the evaluation of a paradental cyst related to the fusion of a wisdom tooth with a paramolar: A rare case report

  • Ozcan, Gozde;Sekerci, Ahmet Ercan;Soylu, Emrah;Nazlim, Sinan;Amuk, Mehmet;Avci, Fatma
    • Imaging Science in Dentistry
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    • v.46 no.1
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    • pp.57-62
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    • 2016
  • Fusion is an abnormality of tooth development defined as the union of two developing dental germs, resulting in a single large dental structure. This irregular tooth morphology is associated with a high predisposition to dental caries and periodontal diseases. As a result of recurring inflammatory periodontal processes, disorders such as periodontal pocket, pericoronitis, and paradental cysts may develop. A rare mandibular anatomic variation is the retromolar canal, which is very significant for surgical procedures. The fusion of a paramolar and mandibular third molar associated with a paradental cyst co-occurring with the presence of a retromolar canal is rare, and the aim of the present study is to describe the evaluation of this anatomical configuration using cone-beam computed tomography.

The effect of beam section property on the behavior of modular prefabricated steel moment connection

  • Kazemi, Seyed Morteza;Sohrabi, Mohammad Reza;Kazemi, Hasan Haji
    • Steel and Composite Structures
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    • v.32 no.6
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    • pp.769-778
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    • 2019
  • The specially prefabricated steel moment connections with pyramid head is one of the significant innovations in the steel structures forms to improve the installation time and simplify the construction procedure. The beams in this structure form are supported by two top and bottom angles and web double angles. Such a configuration despite its advantages increases the welding operation and filed installation time and costs. In this paper, the effect of using beams with channel and I section in three classes of seismically compact, seismically non-compact, and slender section according to width-to-thickness ratio on the behavior of the connection was investigated under monotonic and cyclic loading. Modeling was performed by ABAQUS and verified by the results of an experimental specimen. The findings indicated that using I and channel section instead of angle section reduces the amount of welding materials as well as easing the installation procedure. However, it has no significant effect on the ultimate strength and ductility of the connection. Furthermore, if the beam section is seismically compact, this form is considered as a special moment frame that has a rotation capacity up to 0.04 radians without any reduction in connection moment resistance.