• Title/Summary/Keyword: Force curve

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Corrected equations of motion for a wheel-axle set negotiating an arbitrarily changing radius curve (곡선 경사 선로상 차륜-윤축셋에 대한 수정 운동방정식)

  • Choe, Seong-Gyu
    • Proceedings of the KSR Conference
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    • 2007.11a
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    • pp.940-952
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    • 2007
  • It is found that there are many serious errors in deriving the existing governing equations of motion for a wheel-axle set negotiating an arbitrarily changing radius curve by Vijay K. Garg and Rao V. Dukkipati. Among other things, despite the hypothesis on arbitrarily changing radius of curve, there had been no taking a time derivative of the radius R in the first half of the derivation. Even if the D'lambert force arising from the centrifugal acceleration of vehicle body or bogie was appropriately taken into account while calculating cant deficiency, it is unnecessarily duplicated in the force vectors of governing equations. The graphical model given in Fig. 5.15 is not enough to follow those developed expressions from both physical and structural points of view. Besides, there are some blunders in assigning plus or minus sign not to be regarded as simple typographic ones and similar mistakes are committed in deriving creep force expressions as in the case of a wheel-axle set on a tangent track.

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Influence of Initial Clamping Force of Tension Clamp on Performance of Elastic Rail Fastening System (텐션클램프의 초기 체결력이 탄성레일체결장치의 성능에 미치는 영향)

  • Lee, Dong Wook;Choi, Jung Youl;Baik, Chan Ho;Park, Yong Gul
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.33 no.3
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    • pp.1243-1251
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    • 2013
  • The purpose of this study is to investigate the influence of initial clamping force of tension clamp on the performance of an elastic rail fastening system used in sharp curve track. In this study, the initial clamping force and the increasing lateral wheel loads were conducted in the analytical and experimental study, i.e., finite element analysis, laboratory and field test. Using the analytical and experimental results, the performance of the tension clamp was investigated. It was found that the stress of tension clamp depends on the initial clamping force. Therefore the initial clamping force appeared to directly affect the compression stress of the tension clamp. It was found that the compression stress of tension clamp was transferred to the tensile stress by applied the lateral wheel load in service sharp curve track. Further, it was concluded that the initial clamping force was applied on the strengthening force for the tension clamp and then the appropriate initial clamping force was important to ensure a stable performance and long term endurance of tension clamp.

Determination of the Nonlinear Parameters of Stiffness and Force Factor of the Loudspeaker (스피커 지지부 강성과 Force Factor의 비선형계수 추출)

  • Doo, Se-Jin;Sung, Koeng-Mo
    • The Journal of the Acoustical Society of Korea
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    • v.14 no.5
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    • pp.29-35
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    • 1995
  • Nonlinear distortion arising from the nonlinear movement of the loudspeaker diaphragm degradates the tone quality. The distortion is, in low frequency range, mainly caused by nonlinear characteristics of the suspension stiffness and the force factor. In this paper, the nonlinear suspension stiffness and the nonlinear force factor are modeled to the quadratic functions and a method is proposed to determine their coefficients. An additional mass to the diaphragm moved the quiescent point of the diaphragm and uncoupled the stiffness and the force factor. This made it possible to deter mine the coefficients of the nonlinear suspension stiffness by measuring the resonance frequencies at several quiescent points. The coefficients of the nonlinear force factor are then determined by fitting the curve which is calculated from the waveforms of input voltage and input current, and the displacement of the diaphragm at resonance frequency.

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Analysis of dynamic behavior for truss cable structures

  • Zhang, Wen-Fu;Liu, Ying-Chun;Ji, Jing;Teng, Zhen-Chao
    • Steel and Composite Structures
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    • v.16 no.2
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    • pp.117-133
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    • 2014
  • Natural vibration of truss cable structures is analyzed based upon the general structural analysis software ANSYS, energy variational method and Rayleigh method, the calculated results of three methods are compared, from which the characteristics of free-vibration are obtained. Moreover, vertical seismic response analysis of truss cable structures is carried out via time-history method. Introducing three natural earthquake waves calculated the results including time-history curve of vertical maximal displacement, time-history curve of maximal internal force. Variation curve of maximal displacement of node along span, and variation curve of maximal internal force of member along span are presented. The results show the formulas of frequencies for truss cable structures obtained by energy variational method are of high accuracy. Furthermore, the maximal displacement and the maximal internal force occur near the 1/5 span point. These provide convenient and simple design method for practical engineering.

Evaluation of Curving Performance and Running Safety of New High-Power Electric Locomotive (신형 고출력 전기기관차의 곡선추종성 및 주행안전성 평가)

  • Ham, Young Sam
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.37 no.6
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    • pp.827-832
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    • 2013
  • In this study, curve responsiveness was assessed based on the lateral force and running safety was evaluated based on the wheel unloading ratio and derailment coefficient, which is the ratio of the wheel load and the lateral force. The evaluation of the curving performance and running safety of the new high-power electric locomotive showed that the derailment coefficient appeared higher when the wheel-set was set to the front of the train instead of being placed backward, and the maximum value of the derailment coefficient was recorded as 0.572 on the Gyeongbu line. Furthermore, the lateral force increased in curved sections, and it appeared to be proportional to the curve radius. Meanwhile, a maximum axis lateral force of 77.6 kN was recorded on the Taebaek line, and the wheel unloading ratio was 47.6% on the Yeongdong line. Finally, the running safety at the maximum speed as well as the through-curve performance of the curve radius satisfied the required standards.

Numerical Simulation of Acoustic Field Interacting between a Vortex Ring and a Rigid Sphere (원형 고리와와 강체구의 상호작용에 의한 음향장 수치해석)

  • 유기완;이덕주
    • Journal of KSNVE
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    • v.7 no.2
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    • pp.215-222
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    • 1997
  • The flow and acoustic fields due to a vortex ring interaction with a rigid sphere are simulated numerically. The flow field is regarded as three-dimensional inviscid and incompressible. The vorticity is assumed to be concentrated inside the finite core of vortex filament. The vortex filament curve, described by parabolic blending curve function, is used to effectively solve the modified Biot-Savart equation. The interaction between a vortex ring and a rigid sphere using the parabolic blending curve is calculated. The trajectory of the vortex ring is obtained with several different initial positions between the ring and the sphere. The force variations acting on the sphere are calculated by using the boundary integral method. Finally, we can also obtain the acoustic signals at the far field observation positions from the force variations acting on the rigid surface. We can find that the dipole axis of the directivity patterns are rotated during the interacting phenomena.

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A Study on the Cost-Volume-Profit Analysis Adjusted for Learning Curve (C.V.P. 분석에 있어서 학습곡선의 적용에 관한 연구)

  • 연경화
    • Journal of Korean Society of Industrial and Systems Engineering
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    • v.5 no.6
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    • pp.69-78
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    • 1982
  • Traditional CVP (Cost-Volume-Profit) analysis employs linear cost and revenue functions within some specified time period and range of operations. Therefore CVP analysis is assumption of constant labor productivity. The use of linear cost functions implicity assumes, among other things, that firm's labor force is either a homogenous group or a collection homogenous subgroups in a constant mix, and that total production changes in a linear fashion through appropriate increase or decrease of seemingly interchangeable labor unit. But productivity rates in many firms are known to change with additional manufacturing experience in employee skill. Learning curve is intended to subsume the effects of all these resources of productivity. This learning phenomenon is quantifiable in the form of a learning curve, or manufacturing progress function. The purpose d this study is to show how alternative assumptions regarding a firm's labor force may be utilize by integrating conventional CVP analysis with learning curve theory, Explicit consideration of the effect of learning should substantially enrich CVP analysis and improve its use as a tool for planning and control of industry.

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A Study of Bite Force of the Male Patients with TMJ Dysfunction (악관절기능장애환자(남성)의 교합력에 관한 연구)

  • 강규욱;이승우
    • Journal of Oral Medicine and Pain
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    • v.10 no.1
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    • pp.63-71
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    • 1985
  • A kinematical study of bite force during voluntary isometric contraction was investigated in 20 Korean men with TMJ dysfunction and 30 Korean men as normal subject, ranging from 20 to 27 years old. The author observed maximum bite force, slope of bite force graph, curve index and duration of maximum bite force with the use of the foil strain gauge (MPM-3000) and RS Dymograph (Beckman). The obtained results were as follows : 1. Maximum bite forces were 29kg and 29kg for left and right side of normal subject (p>0.05) and 19kg and 29kg for affected and non-affected side of TMJ dysfunction patient. 2. The slopes of bite force graph were $68^{\circ}$ and $68^{\circ}$ for left and right side of normal subject (p>0.05) and $59^{\circ}$ and $71^{\circ}$ for affected and non-affected side of TMJ dysfunction patient. (p<0.01) 3. The curve indices were 0.93 and 0.90 for left and right side of normal subject and 1.10 and 0.90 for affected and non-affected side of TMJ dysfunction patient. (p>0.05) 4. The durations of maximum bite force were 424 msec and 413 msec for left and right side of normal subject and 337 msec and 334 msec for affected and non-affected side of TMJ dysfunction patient. (p>0.05)

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A Study of Bite Force of the Patients with TMJ Dysfunction (악관절 기능장애환자의 교합력에 관한 연구)

  • 이민규;이승우
    • Journal of Oral Medicine and Pain
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    • v.9 no.1
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    • pp.139-145
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    • 1984
  • A Kinematical study of bite force during voluntary isometric contraction was investigated in 20 Korean women with TMJ dysfunction and 50 Korean women a normal subject, ranging from 19 to 29 years old. The author observed maximal bite force, slope of bite force graph, curve index and duration of maximal bite force by way of the foil strain guage(MPM-3000) and Dymograph(Beckman). The obtained results were as follows : 1. Maximal bite forces were 26.48kg and 21.38kg for left and right side of normal subject and 12.85kg and 20.70kg for affected and mon-affected side of TMJ dysfunction patients. 2. The slope of bite force graph were 64.69。and 63.83。 for left and right side of normal subject and 53.14。and 69.57。for affected and non-affected side. 3. The curve indexes were 0.54 and 0.80 for left and right side of normal subject and 2.30 and 0.60 for affected and non-affected side. 4. The duration of maximal bite force were 383.12 msec and 393.60 msec for left and right side of normal subject and 345.30 msec and 312.25 msec for affected and non-affected side.

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The Estimation of Fatigue Strength of Structure with Practical Dynamic Force by Inverse Problem and Lethargy Coefficient (구조물의 피로강도평가를 위한 역문제 및 무기력계수에 의한 실동하중해석)

  • 양성모;송준혁;강희용;노홍길
    • Transactions of the Korean Society of Automotive Engineers
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    • v.12 no.1
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    • pp.106-113
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    • 2004
  • Most of mechanical structures are composed of many substructures connected to one another by various types of mechanical joints. In automotive engineering, it is important to study these connected structures under various dynamic forces for the evaluations of fatigue life and stress concentration exactly. In this study, the dynamic response of vehicle structure to external forces is classified an inverse problem involving strains from the experiment and the analysis. The practical dynamic forces are determined by the combination of the analytical and experimental method with analyzed strain by quasi-static finite element analysis under unit force and with measured strain by a strain gage under driving load, respectively. In a stressed body, inter-molecular chemical bonds are failed beyond the certain magnitude. The failure of molecular structure in material is considered as a time process of which rate is determined by mechanical stress. That is, the failure of inter-molecular chemical bonds is the fatigue lift of material. This kinetic concept is expressed as lethargy coefficient. And S-N curve is obtained with the lethargy coefficient from quasi-static tensile test. Equivalent practical dynamic force is obtained from the identification of practical dynamic force for one loading point. Using the practical dynamic force and S-N curve, fatigue life of a window pillar is analyzed with FEM under the identified force by the procedure of above mentioned.