• Title/Summary/Keyword: thermal impact

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Vibroacoustic analysis of stiffened functionally graded panels in thermal environments

  • Ashish K. Singh;Anwesha Pal;Shashi Kumar;Anuja Roy;Atanu Sahu
    • Structural Engineering and Mechanics
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    • v.89 no.5
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    • pp.437-452
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    • 2024
  • Functionally graded materials (FGMs) have gained substantial attention from researchers due to their exceptional strength and thermal resistance. Their utilization in the aviation and automobile industries has significantly improved the efficiency of various structural components. Moreover, stiffened panels find wide applications in aerospace and automobile structures and these panels are frequently exposed to extreme environments. It is from this perspective that our research is focused on analysing the vibroacoustic response of stiffened functionally graded panels subjected to external dynamic excitations in a thermal environment. In the present research work, a finite element model is developed to conduct the dynamic analysis of functionally graded stiffened panels using the first-order shear deformation theory. Subsequently, a boundary element based model is also developed and coupled with the finite element model to investigate the sound radiation behaviour of those panels in a thermal environment. The material properties of FG stiffened panels are considered as temperature dependent, while the thermal environment is assumed to be acting as linearly varying through the panel's thickness. The present investigation aim to compare the vibroacoustic responses of different panels due to stiffener orientations, material compositions, power law indices and plate thicknesses at various temperatures. The research findings highlight the significant impact of addition of stiffeners, its orientation and material compositions on the sound radiation characteristics of these panels under thermal environments. The present numerical model can easily be employed for analysing the sound radiation behaviour of other types of flat or curved stiffened panels having arbitrary geometry and boundary conditions.

A Study on Environmental Impact Assessment Guidelines for Marine Environments in Construction Projects of Thermal Power Plant (화력발전소 건설사업의 해양환경 환경영향평가 가이드라인(안) 연구)

  • Maeng, Junho;Kim, Eunyoung;Kang, Taesoon;Son, Minho
    • Journal of Environmental Impact Assessment
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    • v.26 no.1
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    • pp.78-92
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    • 2017
  • Environmental impact assessment(EIA) on the construction and operation of thermal power plant(TPP) is aimed at promoting sustainable coastal development by clearly identifying the marine physics and organisms effects of the project on the surrounding marine environment and minimizing its impact. The primary purpose of this study is to establish EIA guidelines for TPP in order to assess how TPP construction projects influence marine environment and to establish the mitigaion plans of environmental impacts. Through this study, scientific and efficient EIA guidelines for the marine environments were established by a specialist forum consisted of officials from the Ministry of Environment and the Ministry of Trade, Industry and Energy, personnel from five public corporations in charge of TPPs and marine environment experts. In the study, fifteen EIA reports (2009~2015) on TPPs submitted were analyzed to identify the shortcomings of current assessment items on marine environment and to collect a wide range of information including EIA report formulation regulations, domestic and overseas environmental survey guidelines and EIA review comments on TPPs. Based on the findings, a specialist forum put together EIA guidelines for TPP construction projects.

Simulations of Thermal Stratification of Daecheong Reservoir using Three-dimensional ELCOM Model (3차원 ELCOM 모형을 이용한 대청호 수온성층 모의)

  • Chung, Se Woong;Lee, Heung Soo;Choi, Jung Kyu;Ryu, In Gu
    • Journal of Korean Society on Water Environment
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    • v.25 no.6
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    • pp.922-934
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    • 2009
  • The transport of contaminants and spatial variation in a deep reservoir are certainly governed by the thermal structure of the reservoir. There has been continuous efforts to utilize three-dimensional (3D) hydrodynamic and water quality models for supporting reservoir management, but the efforts to validate the models performance using extensive field data were rare. The study was aimed to evaluate a 3D hydrodynamic model, ELCOM, in Daecheong Reservoir for simulating heat fluxes and stratification processes under hydrological years of 2001, 2006, 2008, and to assess the impact of internal wave on the reservoir mixing. The model showed satisfactory performance in simulating the water temperature profiles: the absolute mean errors at R3 (Hoenam) and R4 (Dam) sites were in the range of $1.38{\sim}1.682^{\circ}C$. The evaporative and sensible heat losses through the reservoir surface were maximum during August and January, respectively. The net heat flux ($H_n$) was positive from February to September, while the stratification formed from May and continued until September. Instant vertical mixing was observed in the reservoir during strong wind events at R4, and the model reasonably reproduced the mixing events. A digital low-pass filter and zero crossing method was used to evaluate the potential impact of wind-driven internal wave on the reservoir mixing. The results indicated that most of the wind events occurred in 2001, 2006, 2008 were not enough to develop persistent internal wave and effective mixing in the reservoir. ELCOM is a suitable 3D model for supporting water quality management of the deep and stratified reservoirs.

Analysis of Mechanical Property Changes of Polymer Eyeglass Frames by Thermal Impact (고분자 안경테의 온도에 의한 기계적 물성 변화 분석)

  • Seo, Hogeun;Yoon, Taeyang;Noh, Hyeran
    • Journal of Korean Ophthalmic Optics Society
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    • v.19 no.4
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    • pp.429-434
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    • 2014
  • Purpose: To analyze thermal effect on mechanical properties of domestic commercial polymer-based eyewear frames. Methods: In this study, materials of cellulose acetate, polyamide, epoxy, and polyetherimide were exposed to high or low temperature and were mounted on universal test machine (TO-100-IC) for tensile strength test. Elastic behavior, Young's modulus, maximum displacement, and fatigue were tested with various temperature ($-25^{\circ}C$, $25^{\circ}C$, $60^{\circ}C$). Results: As a result, at room temperature, displacements of materials were changed with increasing impact load. At low temperature ($-25^{\circ}C$), maximum displacements of all specimens were decreased but young's modulus were increased. However, at high temperature, maximum displacements of all specimens were increased but young's modulus were decreased. Conclusions: Degree of displacements due to fatigue behavior was increased following direction of PEI, epoxy, polyamide, acetate. We concluded that commercial polymers used in eyewear frames physical properties were changed differently to exposed temperature.

Prediction of Residual Stress Caused by IML Process and Deformation Due to Thermal Impact (IML 성형과정에 따른 잔류응력 및 열 충격에 의한 변형 예측)

  • Lee, Jae-Won;Jang, Eu-Gene;Shin, Seung-Won;Park, Seung-Ho;Chung, Ha-Seung
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.34 no.3
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    • pp.375-382
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    • 2010
  • In this study, we developed a method to predict the residual stress distribution and thermal deformation caused by in-mold labeling (IML) processes. IML is one of the injection molding processes for injecting a material into a cavity and subsequently inserting a decorated film. The IML process can yield products with decorations of outstanding excellent quality in only one working step. Although the IML process has various advantages, it causes defects such as film delamination, wash-out, and flow marks. In particular, deformation is considered to be a major concern in terms of delamination. To validate the model, the deformation predicted by using a numerical model was compared with experimental results, and both results showed good agreement. We verified that the developed method can be used to obtain the design guidelines for preventing delamination in the initial design stage of the IML process.

Preparation and characterization of isosorbide based PET/polycarbonate blends (Isosorbide가 함유된 바이오 기반 PET와 polycarbonate 블렌드의 제조 및 특성 연구)

  • Park, Ji-Soo;Nam, Byeong-Uk;Park, Jun-Seo
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.15 no.2
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    • pp.1216-1221
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    • 2014
  • Poly(ethylene-co-isosorbide terephthalate) (PEIT) is interest in polymer which has isosorbide monomer that is renewable resources such as corn. However, there is important drawback which is low mechnical properties as increasing isosorbide contents. In this study, polycarbonate used to make up for drawback of mechanical properties of PEIT. In addition, PEIT used to improve the tensile elongation of polycarbonate because PEIT has good sheet proccessability. The effect of polycarbonate on morphology, thermal and mechanical properties were investigated using FE-SEM, DMA, TGA, UTM, and notched izod impact strength tester. As a result of this study, PEIT/PC blends were in compatible system and polycarbonate can act as an improvement of thermal stability and mechanical properties in the blends.

Impact of axial power distribution on thermal-hydraulic characteristics for thermionic reactor

  • Dai, Zhiwen;Wang, Chenglong;Zhang, Dalin;Tian, Wenxi;Qiu, Suizheng;Su, G.H.
    • Nuclear Engineering and Technology
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    • v.53 no.12
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    • pp.3910-3917
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    • 2021
  • Reactor fuel's power distribution plays a vital role in designing the new generation thermionic Space Reactor Power Systems (SRPS). In this paper, the 1/12th SPACE-R's full reactor core was numerically analyzed with two kinds of different axial power distribution, to identify their impacts on thermal-hydraulic and thermoelectric characteristics. In the benchmark study, the maximum error between numerical results and existing data or design values ranged from 0.2 to 2.2%. Four main conclusions were obtained in the numerical analysis: a) The axial power distribution has less impact on coolant temperature. b) Axial power distribution influenced the emitter temperature distribution a lot, when the core power was cosine distributed, the maximum temperature of the emitter was 194 K higher than that of the uniform power distribution. c) Comparing to the cosine axial power distribution, the uniform axial power distribution would make the maximum temperature in each component of the reactor core much lower, reducing the requirements for core fuel material. d) Voltage and current distribution were similar to the axial electrode temperature distribution, and the axial power distribution has little effect on the output power.

UV-Curing System for the Filament Winding of Large Diameter Pipe (대구경 파이프용 필라멘트 와인딩을 위한 UV 경화시스템)

  • Choi, Jae-Wan;Kim, Se-Il;Chung, Yong-Chan;Chun, Byaung-Chul
    • Clean Technology
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    • v.16 no.4
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    • pp.245-253
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    • 2010
  • Optimum conditions for UV-radiated photopolymerization of unsaturated polyester that could be used as protecting layer of large diameter pipe were investigated in this paper. UV photopolymerization method was selected to solve the problems, arising when thermal polymerization by organic peroxide was used, such as the instability of peroxide initiator, the evolution of volatile organic compound, and thermal deformation of product. Two of the photo-initiators (Irgacure 819 and Darocure 1173) well known for its penetrating ability deep into the polymer layer were selected, and the optimum conditions for photopolymerization (1.5 phr initiator content, 1:1.2 initiator ratio, Ga lamp for UV source) were found from the thermal and mechanical test results of the resultant UP polymers. In addition, composite materials containing UP polymer and glass fiber were tested for hardness, impact strength, and flexural strength to find that the impact strength of composite significantly improved.

Mechanical and thermal stability investigation of functionally graded plates resting on visco-Pasternak foundation

  • Samira Hassiba Tagrara;Mohamed Mehdi hamri;Mahmoud Mohamed Selim Saleh;Mofareh Hassan Ghazwani;Abdelbaki Chikh;Abdelmoumen Anis Bousahla;Abdelhakim Kaci;Fouad Bourada;Abdelouahed Tounsi
    • Steel and Composite Structures
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    • v.46 no.6
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    • pp.839-856
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    • 2023
  • This work presents a simple four-unknown refined integral plate theory for mechanical and thermal buckling behaviors of functionally graded (FG) plates resting on Visco-Pasternak foundations. The proposed refined high order shear deformation theory has a new displacement field which includes indeterminate integral variables and contains only four unknowns in which any shear correction factor not used, with even less than the conventional theory of first shear strain (FSDT). Governing equations are deduced from the principle of minimum total potential energy and a Navier type analytical solution is adopted for simply supported FG plates. The Visco-Pasternak foundations is considered by adding the impact of damping to the usual foundation model which characterized by the linear Winkler's modulus and Pasternak's foundation modulus. The accuracy of the present model is demonstrated by comparing the computed results with those available in the literature. Some numerical results are presented to show the impact of material index, elastic foundation type, and damping coefficient of the foundation, on the mechanical and thermal buckling behaviors of FG plates.

Analysis of control rod driving mechanism nozzle rupture with loss of safety injection at the ATLAS experimental facility using MARS-KS and TRACE

  • Hyunjoon Jeong;Taewan Kim
    • Nuclear Engineering and Technology
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    • v.56 no.6
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    • pp.2002-2010
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    • 2024
  • Korea Atomic Energy Research Institute (KAERI) has operated an integral effect test facility, the Advanced Thermal-Hydraulic Test Loop for Accident Simulation (ATLAS), with reference to the APR1400 (Advanced Power Reactor 1400) for tests for transient and design basis accidents simulation. A test for a loss of coolant accident (LOCA) at the top of the reactor pressure vessel (RPV) had been conducted at ATLAS to address the impact of the loss of safety injections (LSI) and to evaluate accident management (AM) actions during the postulated accident. The experimental data has been utilized to validate system analysis codes within a framework of the domestic standard problem program organized by KAERI in collaboration with Korea Institute of Nuclear Safety. In this study, the test has been analyzed by using thermal-hydraulic system analysis codes, MARS-KS 1.5 and TRACE 5.0 Patch 6, and a comparative analysis with experimental and calculation results has been performed. The main objective of this study is the investigation of the thermal-hydraulic phenomena during a small break LOCA at the RPV upper head with the LSI as well as the predictability of the system analysis codes after the AM actions during the test. The results from both codes reveal that overall physical behaviors during the accident are predicted by the codes, appropriately, including the excursion of the peak cladding temperature because of the LSI. It is also confirmed that the core integrity is maintained with the proposed AM action. Considering the break location, a sensitivity analysis for the nodalization of the upper head has been conducted. The sensitivity analysis indicates that the nodalization gave a significant impact on the analysis result. The result emphasizes the importance of the nodalization which should be performed with a consideration of the physical phenomena occurs during the transient.