• 제목/요약/키워드: Vibration Stress

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Improvement and Evaluation of Structural Performance of Steel Fiber Reinforced Concrete Beams Using Early Age Concrete (초기재령 강섬유보강 철근콘크리트 보의 구조성능 평가 및 개선)

  • Ha, Gee-Joo;Shin, Jong-Hack;Kwak, Yoon-Keun;Kwon, Chil-Sung
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.3 no.3
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    • pp.129-137
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    • 1999
  • Reinforced concrete structures using early age concrete were result in the degradation of structural performance due to crack, overload, unexpected vibration and impact load. It demands urgently that reinforced concrete structure using early age concrete should be improved the serviceability and structural performance with the application of new fiber materials. Therefore specimens, designed by the test varibles, such as with or without stirrup and percent of steel fiber incorporated, were constructed and tested to evaluate and develop the structural performance of reinforced steel fiber concrete beam. Based on the test results reported in this study, the following conclusions are made. Specimens, designed by the over 0.75% of steel fiber incorporated, were showed the ductile behavior and failed slowly with flexure and flexure-shear. Comparing with the load-displacement relationship of specimen BSS, designed by the recommendations of the Ministry of Construction and Transportation, reinforced steel fiber concrete beam using early age concrete, over 0.75% of steel fiber incorporated, gets enough load carrying capacity and ductility. Increasing the percent of steel fiber incorporated(0.25~2.0%), the ultimate shear stress of each specimen were increased 12~40% than that of control specimen SSS.

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Optimum design of steel floor system: effect of floor division number, deck thickness and castellated beams

  • Kaveh, A.;Ghafari, M.H.
    • Structural Engineering and Mechanics
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    • v.59 no.5
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    • pp.933-950
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    • 2016
  • Decks, interior beams, edge beams and girders are the parts of a steel floor system. If the deck is optimized without considering beam optimization, finding best result is simple. However, a deck with higher cost may increase the composite action of the beams and decrease the beam cost reducing the total cost. Also different number of floor divisions can improve the total floor cost. Increasing beam capacity by using castellated beams is other efficient method to save the costs. In this study, floor optimization is performed and these three issues are discussed. Floor division number and deck sections are some of the variables. Also for each beam, profile section of the beam, beam cutting depth, cutting angle, spacing between holes and number of filled holes at the ends of castellated beams are other variables. Constraints include the application of stress, stability, deflection and vibration limitations according to the load and resistance factor (LRFD) design. Objective function is the total cost of the floor consisting of the steel profile cost, cutting and welding cost, concrete cost, steel deck cost, shear stud cost and construction costs. Optimization is performed by enhanced colliding body optimization (ECBO), Results show that using castellated beams, selecting a deck with higher price and considering different number of floor divisions can decrease the total cost of the floor.

3D Dynamics of the Oscillating-Moving Load Acting in the Interior of the Hollow Cylinder Surrounded with Elastic Medium

  • Akbarov, Surkay D.;Mehdiyev, Mahir A.
    • Structural Engineering and Mechanics
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    • v.71 no.6
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    • pp.713-738
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    • 2019
  • In the paper the dynamics of the oscillating moving load acting in the interior of the hollow cylinder surrounded with elastic medium is studied within the scope of the exact field equations of 3D elastodynamics. It is assumed that the oscillating load act on the certain arc of the internal circle of the cylinder's cross section and this load moves with constant velocity along the cylinder's axis. The corresponding 3D dynamic problem is solved by employing moving coordinate system, the exponential Fourier transform and the presentation these transforms with the Fourier series. The expressions of the transforms are determined analytically, however their originals are found numerically. Under the investigations carried out in the paper the main attention is focused on the so-called "gyroscopic effect", according to which, the influence of the vibration frequency on the values of the critical velocity and interface stresses are determined. Numerical results illustrated this effect are presented and discussed. In particular, it is established how the non-axisymmetricity of the problem acts on the influence of the load oscillation on its critical velocity and on the interface stresses.

Solder Joints Fatigue Life of BGA Package with OSP and ENIG Surface Finish (OSP와 ENIG 표면처리에 따른 BGA 패키지의 무연솔더 접합부 피로수명)

  • Oh, Chulmin;Park, Nochang;Hong, Wonsik
    • Korean Journal of Metals and Materials
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    • v.46 no.2
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    • pp.80-87
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    • 2008
  • Many researches related to the reliability of Pb-free solder joints with PCB (printed circuit board) surface finish under thermal or vibration stresses are in progress, because the electronics is operating in hash environment. Therefore, it is necessary to assess Pb-free solder joints life with PCB surface finish under thermal and mechanical stresses. We have investigated 4-points bending fatigue lifetime of Pb-free solder joints with OSP (organic solderability preservative) and ENIG (electroless nickel and immersion gold) surface finish. To predict the bending fatigue life of Sn-3.0Ag-0.5Cu solder joints, we use the test coupons mounted 192 BGA (ball grid array) package to be added the thermal stress by conducting thermal shock test, 500, 1,000, 1,500 and 2,000 cycles, respectively. An 4-point bending test is performed in force controlling mode. It is considered that as a failure when the resistance of daisy-chain circuit of test coupons reaches more than $1,000{\Omega}$. Finally, we obtained the solder joints fatigue life with OSP and ENIG surface finish using by Weibull probability distribution.

Structural Analysis and Dynamic Characteristics Analysis of CNC Automatic Lathe Structure (CNC 복합 자동선반 구조물의 구조해석 및 동특성 분석에 관한 연구)

  • Yang, Dong-Ho;Lee, Sang-Hyeop;Cha, Seung-Hwan;Kwak, Jin;Lee, Jong-Chan;Lee, Young-Sik
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.21 no.7
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    • pp.21-27
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    • 2022
  • This study was conducted to evaluate the structural stability of a CNC automatic lathe structure and avoid resonance. The analysis conditions were analyzed by applying the weight of the upper assembly. From the structural analysis, the stress and deformation were low, and the safety factor was high. From the dynamic characteristic analysis, it was determined that resonance does not occur because the natural frequency is outside the driving range. The error between the dynamic characteristic analysis and vibration test results is very low; thus, the reliability of the analysis results can be secured.

Application of machine learning and deep neural network for wave propagation in lung cancer cell

  • Xing, Lumin;Liu, Wenjian;Li, Xin;Wang, Han;Jiang, Zhiming;Wang, Lingling
    • Advances in nano research
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    • v.13 no.3
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    • pp.297-312
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    • 2022
  • Coughing and breath shortness are common symptoms of nano (small) cell lung cancer. Smoking is main factor in causing such cancers. The cancer cells form on the soft tissues of lung. Deformation behavior and wave vibration of lung affected when cancer cells exist. Therefore, in the current work, phase velocity behavior of the small cell lung cancer as a main part of the body via an exact size-dependent theory is presented. Regarding this problem, displacement fields of small cell lung cancer are obtained using first-order shear deformation theory with five parameters. Besides, the size-dependent small cell lung cancer is modeled via nonlocal stress/strain gradient theory (NSGT). An analytical method is applied for solving the governing equations of the small cell lung cancer structure. The novelty of the current study is the consideration of the five-parameter of displacement for curved panel, and porosity as well as NSGT are employed and solved using the analytical method. For more verification, the outcomes of this reports are compared with the predictions of deep neural network (DNN) with adaptive optimization method. A thorough parametric investigation is conducted on the effect of NSGT parameters, porosity and geometry on the phase velocity behavior of the small cell lung cancer structure.

Shock Analysis of Mobile Power Supply Container for Radar with MIL-STD-810H (MIL-STD-810H를 적용한 레이더 전력공급용 이동식 컨테이너의 충격해석)

  • Kwon, Jaeeon;Shin, Dongwon;Hur, Jangwook
    • Journal of the Korea Institute of Military Science and Technology
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    • v.24 no.6
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    • pp.569-576
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    • 2021
  • Radar is a ground defense system that detects enemy aircraft and receives power from a mobile power supply in an emergency. Serious problems may occur if the equipment is damaged by impact during transportation for use. The US military standard MIL-STD-810H contains information on environmental tests such as shock and vibration applied to munitions. Therefore, in this study, the transient analysis of ANSYS 19.2 was performed using the impact data specified in MIL-STD-810H as an input value. Through this, the maximum stress generated in the impact environment of the mobile power supply container was derived, and the safety margin was calculated to confirm the reliability of the container.

A novel hybrid control of M-TMD energy configuration for composite buildings

  • ZY Chen;Yahui Meng;Ruei-Yuan Wang;T. Chen
    • Steel and Composite Structures
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    • v.48 no.4
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    • pp.475-483
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    • 2023
  • In this paper, a new energy-efficient semi-active hybrid bulk damper is developed that is cost-effective for use in structural applications. In this work, the possibility of active and semi-active component configurations combined with suitable control algorithms, especially vibration control methods, is explored. The equations of motion for a container bridge equipped with an MDOF Mass Tuned Damper (M-TMD) system are established, and the combination of excitation, adhesion, and control effects are performed by a proprietary package and commercial custom submodel software. Systematic methods for the synthesis of structural components and active systems have been used in many applications because of the main interest in designing efficient devices and high-performance structural systems. A rational strategy can be established by properly controlling the master injection frequency parameter. Simulation results show that the multiscale model approach is achieved and meets accuracy with high computational efficiency. The M-TMD system can significantly improve the overall response of constrained structures by modestly reducing the critical stress amplitude of the frame. This design can be believed to build affordable, safe, environmentally friendly, resilient, sustainable infrastructure and transportation.

On the wave propagations of football game ball after contacting with the player foot

  • Lei Sun;Cancan Wei;Fei Liu;Lijun Wang;Bo Ren
    • Geomechanics and Engineering
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    • v.33 no.6
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    • pp.529-542
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    • 2023
  • Wave propagation with high transverse deflection could affect the stability of the ball in its trajectory. For low stiffness balls similar to soccer and volleyball balls, the waves are more noticeable in comparison to other balls like ping-pong ball. On the other hand, the soccer balls are under heavy impact loads from shoots and contacting different objects in the field. The maximum recorded speed of a soccer ball after kicking is the 211 km/hr and the average maximum speed is around 112 km/hr. Therefore, in such speeds the aerodynamic forces become important which are directly related to geometrical shape of the ball. In this regard, the wave propagation in soccer ball is examined in the current study using large deformation shear deformable formulations. Classical relations of stress-strain components are taken into consideration along with minimum total energy principle. The final derived relations were solved by using harmonic differential quadrature method. The results are generally presented ion term of phase velocity as function of different influencing parameters of the materials, geometry and mass of the ball.

Evaluation of Scratch Characteristics of Diaphragm for Application of Hydrogen Compressor Parts

  • Sung-Jun Lee;Chang-Lae Kim
    • Tribology and Lubricants
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    • v.39 no.5
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    • pp.212-215
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    • 2023
  • Diaphragm compressors play a crucial role in safely compressing large volumes of high-purity hydrogen gas without contamination or leakage, thereby ensuring quality and reliability. Diaphragm compressors use a thin, flat, triple-layered diaphragm plate that is subjected to repetitive piston pressure for compression. They are usually made of metallic materials such as stainless steel or Inconel owing to their high-pressure resistance. However, since they are consumable components, they fail due to fatigue from repetitive pressure and vibration stress. This study aims to evaluate the scratch characteristics of diaphragms in operational environments by conducting tests on three different samples: Inconel 718, AISI 301, and Teflon-coated AISI 301. The Inconel 718 sample underwent a polishing process, the AISI 301 sample used raw material, and the Teflon coating was applied to the AISI 301 substrate at a thickness of 50 ㎛. To assess the scratch resistance, reciprocating motion friction tests were performed using a tribometer, utilizing 220 and 2000 grit sandpapers as the counter materials. The results of the friction tests suggested that the Teflon-coated sample exhibited the lowest initial friction coefficient and consistently maintained the lowest average friction coefficient (0.13 and 0.11 with 220 and 2000 grit, respectively) throughout the test. Moreover, the Teflon-coated diaphragm showed minimal wear patterns, indicating superior scratch resistance than the Inconel 718 and AISI 301 samples. These findings suggest that Teflon coatings may offer an effective solution for enhancing scratch resistance in diaphragms, thereby improving compressor performance in high-pressure hydrogen applications.