• Title/Summary/Keyword: Non-material Factors

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Thermal flow intensity factor for non-homogeneous material subjected to unsteady thermal load (비정상 열 하중을 받는 이질재료의 열량 집중 계수 해석)

  • Kim, Gui-Seob
    • Journal of the Korean Society for Aviation and Aeronautics
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    • v.16 no.4
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    • pp.26-34
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    • 2008
  • This article provides a comprehensive treatment of cracks in non-homogeneous structural materials such as functionally graded materials (FGMs). It is assumed that the material properties depend only on the coordinate perpendicular to the crack surfaces and vary continuously along the crack faces. By using laminated composite plate model to simulate the material non-homogeneity, we present an algorithm for solving the system based on Laplace transform and Fourier transform techniques. Unlike earlier studies that considered certain assumed property distributions and a single crack problem, the current investigation studies multiple crack problem in the FGMs with arbitrarily varying material properties. As a numerical illustration, transient thermal flow intensity factors for a metal-ceramic joint specimen with a functionally graded interlayer subjected to sudden heating on its boundary are presented. The results obtained demonstrate that the present model is an efficient tool in the fracture analysis of non-homogeneous material with properties varying in the thickness direction.

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Multi-Crack Problems for Non-homogeneous Material Subjected to Unsteady Thermal Load (비정상 열 하중을 받는 이질재료의 다중 크랙 문제)

  • Kim, Kui-Seob
    • Journal of the Korean Society for Aviation and Aeronautics
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    • v.19 no.1
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    • pp.15-23
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    • 2011
  • The purpose of this paper is to investigate the time behavior of a multiple crack problems. It is assumed that the medium contains cracks perpendicular to the crack surfaces, that the thermo-mechanical properties are continuous functions of the thickness coordinate. we use the laminated composite plate model to simulate the material non-homogeneity. By utilizing the Laplace transform and Fourier transform techniques, the multiple crack problems in the non-homogeneous medium is formulated. Singular integral equations are derived and solved to investigate the multiple crack problems. As a numerical illustration, transient thermal stress intensity factors(TSIFs) for a functionally graded material plate subjected to sudden heating on its boundary are provided. The variation in the TSIFs due to the change in material gradient and the crack position is studied.

A Study on the Crack Growth Behavior of a Inclined Crack in a Non-Uniform Thickness Material (두께가 일정하지 않은 재료에서 경사진 균열의 성장거동에 관한 연구)

  • 조명래;표창률;박종주;고명훈
    • Journal of the Korean Society of Safety
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    • v.12 no.4
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    • pp.27-38
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    • 1997
  • The effect of geometry factors on the combined mode stress intensity factor behaviors of a slant crack in a non-uniform thickness material was analysed by 2-dimensional theoretical analysis. The analysis is based on the Laurent's series expansions of complex potentials where the complex coefficients of the series are determined from the compatibility and the equilibrium conditions of the thickness interface and the stress free conditions of the crack surface. In numerical calculations the perturbation technique is employed. The expressions for the crack tip stress intensity factor are given in the form of power series of dimensionless crack length $\lamda$, and the function of crack slant angle $\alpha$ and thickness ratio $\beta$. The results of numerical calculations for each problems are represented as the correction factors F($\lamda$, $\alpha$, $\beta$). The results clearly show the following characteristics : The correction factors of the combined mode stress intensity factors for a non-uniform thickness material can be defined in the form of F($\lamda$, $\alpha$, $\beta$). The stress intensity factor values for a given crack length are decreased with increase of thickness ratio $\beta$.

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Shape optimization of a bow for maximizing internal-energy (내부에너지를 최대로 하는 활 구조의 최적화)

  • Moon, Myeong-Jo;Lee, Hyun-Jung
    • Proceeding of EDISON Challenge
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    • 2016.03a
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    • pp.222-227
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    • 2016
  • In this paper, the optimized design for bow structure was investigated by using EDISON software. Considering the mechanism of the bow, non-linear FEM analysis was essential. The factors of the design are height, width, number of holes and taper value. High performance of the internal energy and lowest mass were main issues. The limit of the von-mises stress was yield strength for the material. Material was chosen by considering typical bow material, Aluminum. Using Taguchi method($L_9$), 9 models were selected and contribution rate was calculated for each factors. Following the contribution rate, 3 factors were fixed and optimized model was predicted. After making optimized model for FEM analysis, the value of internal-energy, mass for FEM model were compared with predicted value, calculated the percentage error and figure out the reliability of Taguchi method.

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The Non-Linear Characteristics of ZnO Devices. (ZnO 소자의 비직선 특성)

  • Hong, Kyung-Jin;Chon, Kyung-Nam;Cho, Jae-Cheol
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2001.05a
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    • pp.43-46
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    • 2001
  • The ZnO devices using semiconductor properties, to include $MnO_2$, $Y_2O_3$ and other material, was fabricated by $Sb_2O_3$ mol ratio from 1 to 4 [mol%]. The non-linearity factor was calculated by setting current to be $1[mA/cm^2]$ and $10[mA/cm^2]$. The spinel structure was fonned by $Sb_2O_3$ addition and it was depressed the ZnO grain formation. The grain growing was controlled by spinel structure that has improved the non-linearity factors. The breakdown voltage characteristics of semiconductor devices to increase with $Sb_2O_3$ was increased in voltage-current. The non-linearity value of ZnO semiconductor devices was 45 over.

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A Study on the Relationship between Space and Space Experience (공간과 공간경험의 관계에 대한 연구)

  • 오창섭
    • Korean Institute of Interior Design Journal
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    • v.13 no.2
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    • pp.91-99
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    • 2004
  • This study aims to embody material and non-material factors forming space and to explain our experience in space. Space is formed by material factors and their disposition. One space becomes a new space by such factors 'arrangement. Nevertheless, one space is never swayed by material factors and their disposition. Space is a reflection of social relations and historical process, and is also affected by its users. Space can not neutrally exist, for it compels its users to keep a specific life style. Space users have experience in space by practice. Practice enables its users to experience various relationships space makes, and as well it allows them to have creative experience in space by twisting them and inducing a new relationship.

A partial factors methodology for structural safety assessment in non-linear analysis

  • Castro, Paula M.R.P.;Delgado, Raimundo M.;Cesar de Sa, Jose M.A.
    • Computers and Concrete
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    • v.2 no.1
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    • pp.31-53
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    • 2005
  • In the present structural codes the safety verification is based on a linear analysis of the structure and the satisfaction of ultimate and serviceability limit states, using a semi-probabilistic security format through the consideration of partial safety factors, which affect the action values and the characteristic values of the material properties. In this context, if a non-linear structural analysis is wanted a difficulty arises, because the global safety coefficient, which could be obtained in a straightforward way from the non-linear analysis, is not directly relatable to the different safety coefficient values usually used for the different materials, as is the case for reinforced concrete structures. The work here presented aims to overcome this difficulty by proposing a methodology that generalises the format of safety verification based on partial safety factors, well established in structural codes within the scope of linear analysis, for cases where non-linear analysis is needed. The methodology preserves the principal assumptions made in the codes as well as a reasonable simplicity in its use, including a realistic definition of the material properties and the structural behaviour, and it is based on the evaluation of a global safety coefficient. Some examples are presented aiming to clarify and synthesise all the options that were taken in the application of the proposed methodology, namely how to transpose the force distributions obtained with a non-linear analysis into design force distributions. One of the most important features of the proposed methodology, the ability for comparing the simplified procedures for second order effects evaluation prescribed in the structural codes, is also presented in a simple and systematic way. The potential of the methodology for the development and assessment of alternative and more accurate procedures to those already established in codes of practice, where non-linear effects must be considered, is also indicated.

Comparative Study of Major factors of Customer Satisfaction between Franchise and Non-Franchise Skin-care & Obesity Clinics in Pusan (부산지역 프랜차이즈피부비만관리실과 일반피부비만관리실의 고객만족도 영향요인)

  • Chung, Young-Ae;Kim, Un-Sin;Bae, Sung-Kwon
    • The Korean Journal of Health Service Management
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    • v.3 no.2
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    • pp.55-64
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    • 2009
  • The purpose of this study was to examine the use of skincare & obesity clinics, customer satisfaction with franchise and non-franchise skincare & obesity clinics and customer selection criteria in the region of Busan in a bid to suggest some of the right directions for marketing strategies for the inauguration of skincare & obesity clinics. The subjects in this study were 240 users of 16 different skincare & obesity clinics selected from Busan. Out of the clinics, four franchise clinics and four non-franchise clinics were selected from the major commercial districts, and four franchise clinics and four non-franchise clinics were selected from the residential areas. Concerning the influence of three leading factors on customer satisfaction, all the service price, material service and human service had a significant impact on customer satisfaction in the franchise model for the commercial districts. In the case of the franchise clinics in the residential areas, only service price exerted a significant influence on customer satisfaction. In terms of the non-franchise model for the commercial districts, customer satisfaction was under the significant influence of human service and material service, and that was significantly affected by human service and service price in the non-franchise model for the residential areas.

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Eringen's nonlocal theory for non-linear bending analysis of BGF Timoshenko nanobeams

  • Azandariani, Mojtaba Gorji;Gholami, Mohammad;Nikzad, Akbar
    • Advances in nano research
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    • v.12 no.1
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    • pp.37-47
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    • 2022
  • In this paper, the non-linear static analysis of Timoshenko nanobeams consisting of bi-directional functionally graded material (BFGM) with immovable ends is investigated. The scratching in the FG nanobeam mid-plane, is the source of nonlinearity of the bending problems. The nonlocal theory is used to investigate the non-linear static deflection of nanobeam. In order to simplify the formulation, the problem formulas is derived according to the physical middle surface. The Hamilton principle is employed to determine governing partial differential equations as well as boundary conditions. Moreover, the differential quadrature method (DQM) and direct iterative method are applied to solve governing equations. Present results for non-linear static deflection were compared with previously published results in order to validate the present formulation. The impacts of the nonlocal factors, beam length and material property gradient on the non-linear static deflection of BFG nanobeams are investigated. It is observed that these parameters are vital in the value of the non-linear static deflection of the BFG nanobeam.

A study on the Preference of Material quality and the Demand Performance of Clothing for Underwear Materials (내의 소재에 대한 재질선호 및 요구 성능에 대한 연구)

  • Park, Young-Hee
    • Fashion & Textile Research Journal
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    • v.11 no.1
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    • pp.147-155
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    • 2009
  • This study has been made to examine the basic information, the preferences of material quality, and the demand performance of clothing for underwear materials between atopic patients and non-patients. The measurement tool was a questionnaire. For statistical analysis of data, crosstabs, ${\chi}^2$-test, t-test and ANOVA through SPSS for Windows(version 14.0) were used. The results obtained are as follows. The degree of the basic knowledge about clothing materials indicated that women was higher than men. The material decision method and the most considering part in case of selecting underwear products showed difference between men and women. The preference factors for underwear material quality were drawn with the five factors of sense of weight/pliability, lustering/see-through, tactility, and sense of cold and warmth. The preferred underwear material showed difference according to gender, existence and nonexistence of atopic determatitis, and degree of strength of skin itching caused by clothing materials. The demand performances of clothing in case of selecting underwear were drawn with the four factors of hygiene/practicality, skin protection, quality of materials, and aesthetic attribute. The demand performance of underwear showed difference according to gender, existence and nonexistence of atopic determatitis, degree of strength of skin itching caused by clothing materials.