• 제목/요약/키워드: Newton-Raphson

검색결과 588건 처리시간 0.025초

비선형계량법(非線型計量法)을 이용한 신뢰성(信賴性)의 최적화(最適化) (Reliability Optimization By using a Nonlinear Programming)

  • 이창호
    • 품질경영학회지
    • /
    • 제9권2호
    • /
    • pp.31-36
    • /
    • 1981
  • 점증되고 있는 고신뢰성 제품의 설계에 있어 주어진 선형제약조건 내(內)에서 체계의 신뢰성을 최대화하는 방법을 소개하고 이를 해결하는 비선형계획법을 반복단계로 하여 Computer Programming을 하였다. 단, 본 논문에서 다루는 체계는 병렬중복구조를 갖는 직렬다단계 구조이다. 타당성 검토를 위한 예제를 해결하였으며 Computer Programming은 지면관계로 생략하였다.

  • PDF

실측형상오차를 이용한 HDD 스핀들용 볼베어링의 NRRO 해석 (NRRO analysis of HDD spindle ball bearings using the measured geometric imperfection)

  • 김영철;최상규;윤기찬
    • 한국소음진동공학회:학술대회논문집
    • /
    • 한국소음진동공학회 2002년도 추계학술대회논문집
    • /
    • pp.369-374
    • /
    • 2002
  • This paper presents theoretical analysis of the NRRO(non-repeatable run-out) for a ball bearing with geometric imperfection. The 3DOF dynamic analysis of a ball bearing using the Newton-Raphson method is performed to calculate the displacement of shaft center. Frequency and magnitude characteristics of radial and axial vibrations are investigated. The ball form errors of the ball, the inner race, and the outer race in a HDD spindle ball bearing are precisely measured. NRRO of a ball bearing is analyzed by using the measured waviness data. It is concluded that dominant components of radial vibrations are ${\Large}f_c\;and\;2{\Larg}f_b{\pm}{\Large}f_c$, and dominant component of axial vibrations is $2{\Large}f_b$. These are generated by the size error and the second waviness of the balls.

  • PDF

구름요소의 Waviness 를 고려한 볼베어링 해석 이론 (Analytical Theory of Ball Bearing Considering Waviness of Rolling Elements)

  • 정성원;장건희
    • 한국소음진동공학회논문집
    • /
    • 제11권7호
    • /
    • pp.275-286
    • /
    • 2001
  • The research presents an analytical theory to calculate the characteristics of the bal bearing with waviness in its rolling elements considering the centrifugal force and gyroscopic moment of bal. The effects of centrifugal force and gyroscopic moment are introduced to the kinematic constraints and force equilibrium equations. and the waviness of rolling elements is modeled by sinusoidal function to calculate the contact force at each ball. The numerical solutions of governing equation of berating due to waviness are calculated by using the Newton-Raphson method. The accuracy of the research is validated by comparing the contact force. contact angle in case of considering the centrifugal force and gyroscopic moment of bal and the contact force and vibration frequencies in cases of considering waviness with the prior researches respectively. It investigates the stiffness, contact force. displacement and vibration frequencies of the ball bearing considering not only the centrifugal force and gyroscopic moment of ball but also the waviness of the rolling elements.

  • PDF

비선형성을 고려한 각가속도를 갖는 유연 회전원판의 동적 해석 (Dynamic Analysis of a Flexible Spinning Disk with Angular Acceleration Considering Nonlinearity)

  • 정진태;정두한
    • 소음진동
    • /
    • 제9권4호
    • /
    • pp.806-812
    • /
    • 1999
  • Dynamic behaviors are analyzed for a flexble spinning disk with angular acceleration, considering geometric nonlinearity. Based upon the Kirchhoff plate theory and the von Karman strain theory, the nonlinear governing equations are derived which are coupled equations with the in-plane and out-of-planedisplacements. The governing equations are discretized by using the Galerkin approximation. With the discretized nonlinear equations, the time responses are computed by using the generalized-$\alpha$ method and the Newton-Raphson method. The analysis shows that the existence of angular acceleration increases the displacements of the spinning disk and makes the disk unstable.

  • PDF

유한 베어링 모델링을 이용한 왕복동형 압축기 크랭크축의 동적 거동 및 윤활특성 해석 (Dynamic Behavior and Lubrication Characteristics of a Reciprocating Compressor Crankshaft by n Finite Bearing Model)

  • 김태종
    • Tribology and Lubricants
    • /
    • 제18권6호
    • /
    • pp.402-410
    • /
    • 2002
  • In this study, a hydrodynamic analysis of the reciprocating compressor crankshaft considering a finite bearing modelling of the journal bearings used in small refrigeration compressors is performed. In the problem formulation of the compression mechanism dynamics, all corresponding hydrodynamic forces and moments are considered using the finite bearing analysis in order to determine the crankshaft trajectory at each step. The solution of the Reynolds' equation is determined numerically using a finite difference method and a Newton-Raphson procedure was employed in solving the dynamic equations of the crankshaft. The crankshaft orbits fur the finite bearing model and short bearing theory were used to compare the effect of the hydrodynamic farces of the journal bearings on the dynamic and lubrication characteristics of the crankshaft-journal bearing system. Results show that the finite bearing model for the journal bearings must be considered in calculating for the accurate dynamic characteristics of the reciprocating compressor crankshaft.

A Study on the Air-Lubricated Herringbone Groove Journal Bearing by Finite Element Method

  • Park, Shin Wook;Rhim, Yoon Chul
    • KSTLE International Journal
    • /
    • 제2권1호
    • /
    • pp.46-54
    • /
    • 2001
  • The herringbone groove journal bearing (HGJB) has chevron type grooves on stationary or rotating member of the bearing so that they pump the lubricant inward the grooves when journal rotates. As a result, the pressure is generated around the journal so that the radial stiffness and dynamic stability are improved comparing to the plain journal bearing (PJB) when the bearing operates near the concentric condition. The narrow groove theory, conventionally adopted to simulate the concentric operation of HGJB, is limited to the infinite number of grooves. A numerical study of air-lubricated HGJB is presented for the finite number of grooves. The compressible isothermal Reynolds equation is solved by using Finite Element Method together with the Newton-Raphson iterative procedure and perturbation method. The solutions render the static and dynamic performances of HGJB. Comparison of present results with a PJB validates previously published finite difference solution. The HGJB's geometric parameters influence its static and dynamic characteristics. The optimum geometric parameters are presented for the air-lubricated HGJB in particular conditions.

  • PDF

선단압력을 고려한 무한폭 틸팅-패드 저어널 베어링의 정특성 및 동특성 해석 (An Analysis of the Static and Dynamic Characteristics of Infinite Width Tilting-Pad Journal Bearings in Consideration of Ram-Prssure)

  • 김종수;김경웅
    • Tribology and Lubricants
    • /
    • 제5권2호
    • /
    • pp.68-76
    • /
    • 1989
  • In this paper, the influence of ram-pressure on the static and dynamic characteristics of infinite width tilting-pad journal bearing is investigated theoretically. The ram-pressure is obtained by assumption of conservation of mechanical energy of the lubricant flow through the leading edge of the pad. The pressure in the lubricating film is numerically calculated using the ram-pressure obtained as the inlet pressure boundary condition of the pad. The static equilibrium state of tilting-pad journal bearing is determined by Newton-Raphson iteration method. A numerical results are presented in graphic form and relationships between the ram-pressure and the static and dynamic characteristics are discussed.

소음계 교정 자동화 시스템 개발 및 성능평가 (Development and Performance of Automated Calibration System of Sound Level Meters)

  • 김용태;조문재;이용봉;서재갑;서상준
    • 한국소음진동공학회:학술대회논문집
    • /
    • 한국소음진동공학회 1998년도 춘계학술대회논문집; 용평리조트 타워콘도, 21-22 May 1998
    • /
    • pp.704-709
    • /
    • 1998
  • An automated calibration system of sound level meters was developed and tested. As a standard sound source, the speaker unit(Forstex FE208) cabineted by 440 * 390 * 490 mm$^{3}$(LHW) volume wood box was adopted. Including this source, the driving part was found out to have a good linearity of sound pressure output vs AC input. We use the Hybrid-Bisect, /Newton-Raphson method modified by the linearity as searching algorithm. Personal computer and program do the control, measurements, and calculations and finally do the accumulation of useful data and results. Several trials of automatic calibration using this developed system give reliable results.

  • PDF

A Computationally Efficient Finite Element Analysis Algorithm Considering 2-D Magnetic Properties of Electrical Steel Sheet

  • Yao, Yingying;Li, Wei;Yoon, Hee-Sung;Fujiwara, Koji;Koh, Chang-Seop
    • Journal of Electrical Engineering and Technology
    • /
    • 제3권3호
    • /
    • pp.385-390
    • /
    • 2008
  • For taking account of the two-dimensional magnetic properties of a grain-oriented electrical steel sheet, the effective anisotropic tensor reluctivity is examined, and a computationally efficient algorithm is suggested by using the response surface method to model the two-dimensional magnetic properties. It is shown that the reconstructed two-dimensional magnetic properties are fairly effective to stabilize the convergence characteristics of the Newton-Raphson iteration in the nonlinear magnetic field analysis.

Closed form ultimate strength of multi-rectangle reinforced concrete sections under axial load and biaxial bending

  • da Silva, V. Dias;Barros, M.H.F.M.;Julio, E.N.B.S.;Ferreira, C.C.
    • Computers and Concrete
    • /
    • 제6권6호
    • /
    • pp.505-521
    • /
    • 2009
  • The analysis of prismatic members made of reinforced concrete under inclined bending, especially the computation of ultimate loads, is a pronounced non-linear problem which is frequently solved by discretizing the stress distribution in the cross-section using interpolation functions. In the approach described in the present contribution the exact analytical stress distribution is used instead. The obtained expressions are integrated by means of a symbolic manipulation package and automatically converted to optimized Fortran code. The direct problem-computation of ultimate internal forces given the position of the neutral axis-is first described. Subsequently, two kinds of inverse problem are treated: the computation of rupture envelops and the dimensioning of reinforcement, given design internal forces. An iterative Newton-Raphson procedure is used. Examples are presented.