• Title/Summary/Keyword: Displacement rate

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Development of Displayer on Tipping-over rate for Hydraulic Excavator (유압 굴삭기의 전도율 표시장치의 개발)

  • 임태형;최종환;김용석;이홍선;양순용
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • 2004.04a
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    • pp.209-214
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    • 2004
  • This paper deals with tipping over of hydraulic excavator's crane work. If excavator lift too heavy weight, excavator tipped up. This is 38% of whole excavator accidents. In this paper, tipping over load which is maximum load of excavator can lift with displacement of excavator links, real load and tipping over rate are calculated with Zero Moment Point. We designed the tipping-over stability criterion algorithm considering the dynamic characteristics to which ZMP theory is applied and discussed the usefulness of the proposed algorithm compared with the moment equilibrium equation through the simulation and the actual test.

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Considerations of the Small-Crack Growth Law Based on COD (CRACK 개구변위(開口變位)에 기초한 미소피로(微小疲勞)크랙 전파법칙(法則)의 고찰(考察))

  • Kim, Min-Gun;Ji, Jueng-Keun
    • Journal of Industrial Technology
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    • v.13
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    • pp.49-57
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    • 1993
  • Bending fatigue tests were carried out on the specimenes with two different strength levels in order to investigate small crack growth rate. The main results obtained are as follows : (1) Small crack growth law, $da/dn=C{\sigma}_a{^n}a$ is useful several materials, but is not the rule applicable to all cases generally. (2) When da/dn in several specimens are equal, COD near the crack tip are also nearly equal. (3) Crack tip opening displacement(CTOD) is the main factor to control the small crack growth rate, and da/dn ${\propto}$ CTOD comes into being between the two. Accordingly, $da/dn=C({\sigma}_a{^2}/{\sigma}_s){^n}a^n$ shows the small crack growth rate being reflected crack closure phenomenon.

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An Investigation of Performance Change of Diesel Oxidation Catalyst for Diesel Vehicle (경유차 적용 디젤산화촉매장치의 성능 변화 분석)

  • Hwang, Jin-Woo;Lee, Chang-Sik
    • Journal of ILASS-Korea
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    • v.14 no.1
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    • pp.15-19
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    • 2009
  • This paper is to investigated the analysis of performance characteristics of diesel oxidation catalyst (DOC) for diesel vehicle with 2.5L piston displacement. The performance evaluation test of DOC applied to test diesel vehicle was carried out for four kinds of DOCs manufactured from different company. The testing DOCs were randomly selected from the retrofit vehicle and then standard test vehicle that was representative for the application group was equipped with DOC for the test. In this verification test, the reduction rate of particulate matter (P.M.) and the deviation of the performance of the DOC were examined through CVS-75 mode of the standard vehicle and SOF reduction rate of specific DOC was investigated. It was found that some DOCs failed to pass the criteria of the P.M. reduction rate because of the reason seen catalyst aging even if they were same devices. In the result of SOF analysis, the specific DOC showed more PM reduction than SOF of PM. reduction exceptionally.

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Fast(submillisecond) Switching of Nematic Liquid Crystals and Effects of Dielectric Dispersion; Theory and Experiment

  • Shiyanovskii, Sergij V.;Golovin, Andrii B.;Yin, Ye;Lavrentovich, Oleg D.
    • 한국정보디스플레이학회:학술대회논문집
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    • 2005.07a
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    • pp.181-186
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    • 2005
  • We demonstrate that the finite rate of dielectric relaxation in liquid crystals which has been ignored previously causes profound effects in the fast dielectric reorientation of the director. The phenomenon is relevant for submillisecond switching of the director when the switching rate approaches the rate of dielectric relaxation through the reorientation of the molecular dipoles. A submillisecond switching ($15-400\;{\mu}s$ for an optical retardation shift $0.3-2.2\;{\mu}m$ in $10-15\;{\mu}m$ thick cells) is demonstrated for dual frequency nematic cells with high pretilt that maximizes the dielectric torque acting on the director. We propose the theory of dielectric response in which the electric displacement depends not only on the present (as in the standard theory) but also on the past values of electric field and director. We design an experiment in which the standard "instantaneous" model and our model predict effects of opposite signs; the experimental data support the latter model.

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2D continuum viscodamage-embedded discontinuity model with second order mid-point scheme

  • Do, Xuan Nam;Ibrahimbegovic, Adnan
    • Coupled systems mechanics
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    • v.7 no.6
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    • pp.669-690
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    • 2018
  • This paper deals with numerical modeling of dynamic failure phenomena in rate-sensitive brittle and/or ductile materials. To this end, a two-dimensional continuum viscodamage-embedded discontinuity model, which is based on our previous work (see Do et al. 2017), is developed. More specifically, the pre-peak nonlinear and rate-sensitive hardening response of the material behavior, representing the fracture-process zone creation, is described by a rate-dependent continuum damage model. Meanwhile, an embedded displacement discontinuity model is used to formulate the post-peak response, involving the macro-crack creation accompanied by exponential softening. The numerical implementation in the context of the finite element method exploiting the second-order mid-point scheme is discussed in detail. In order to show the performance of the model several numerical examples are included.

Multilayered inhomogeneous beam under prescribed angle of twist and displacements: A delamination analysis

  • Victor I. Rizov
    • Coupled systems mechanics
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    • v.13 no.2
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    • pp.153-170
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    • 2024
  • The problem considered in this theoretical paper is the delamination of a multilayered inhomogeneous beam structure that has viscoelastic behaviour under angle of twist, horizontal and vertical displacements which vary smoothly with time according to prescribed laws. The cross-section of the beam is a rectangle. The layers are made of different materials which are smoothly inhomogeneous along the length of the beam. The beam under consideration represents statically undetermined structure since it is clamped in its two ends. The problem of the strain energy release rate is solved. For this purpose, the strain energy stored in the beam structure is analyzed. In order to verify the solution obtained, the strain energy release rate is found also analyzing the time-dependent compliances of the beam under prescribed angle of twist and displacements. A parametric investigation is carried-out by applying the solution obtained. Special attention is paid to the effect of the parameters which control the variation of the angle of twist and the displacements with time on the strain energy release rate.

Modified Tei index in patients with Kawasaki disease by tissue doppler imaging (가와사키병 환아에서 Tissue doppler imaging으로 측정한 modified Tei 지수)

  • Kim, Hee Jung;Cha, Jung Hwa;Hong, Young Mi
    • Clinical and Experimental Pediatrics
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    • v.49 no.11
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    • pp.1202-1210
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    • 2006
  • Purpose : A quantitative and easily measured Doppler index of combined systolic and diastolic ventricular myocardial performance (Tei index) was recently proposed as a potentially useful predictor of global myocardial performance. However, presence of heart rate fluctuation makes it unreliable. Therefore, the modified Tei index was introduced by using tissue Doppler imaging (TDI) which enables measuring contraction and relaxation velocities from myocardium simultaneously. The purpose of this study was to investigate the effectiveness of the modified Tei index in the evaluation of global cardiac function. Methods : Forty eight patients in the acute phase of Kawasaki disease (KD) were studied. These patients were divided into two groups according to the modified Tei index. TDI and conventional echocardiography were performed. Systolic velocity, systolic displacement, E' velocity, E' displacement, A' velocity and A' displacement were measured at the base, mid-septum and the apex of the interventricular septum. Ejection fraction (EF), Tei index and modified Tei index were estimated. Results : Modified Tei index correlated negatively with systolic displacement, E' displacement and A' displacement at the base. Modified Tei index correlated positively with ESR and CRP. EF and Tei index were normal in KD patients. Conclusion : Modified Tei index is a safe, feasible and sensitive index for evaluating global ventricular functions in spite of normal EF and Tei index in KD.

The Energy Release Rate of the Two Dimensional Cracked Body Under Thermal Stresses, Body Forces and Crack-Face Tractions (열응력, 내력 및 균열 경계하중을 고려한 2차원 균열문제의 에너지방출율)

  • 이태원
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.17 no.9
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    • pp.2172-2180
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    • 1993
  • Under general loadings, including body forces, crack-face tractions and thermal loading, the energy release rate equation for a two-dimensional cracked body is presented. Defining the virtual crack extension as the variation of the geometry, the equation is directly derived by a shape design sensitivity of the potential energy. Although the form of the derived energy release rate equation is different from other researchers's results, the three example show that the former is exactly the same as the latter. However, the final integral equation do not involve the derivative of the displacement on the crack surface and crack tip region, thereby improving the numerical accuracy in the computation of the energy relase rate. Moreover, as it was derived from the governing equation including non-linear elasticity without special assumptions, the energy release rate of a elasto-plastic fracture can be obtained and any numerical stress analysis method can be applied.

Fabrication and Mechanical Property of Fe-20Cu-1C Compacts by SPS process with Different Heating Rate (방전플라즈마소결법 적용 승온속도 변화에 따라 제조된 Fe-20Cu-1C 소결체 제조 및 특성평가)

  • Ryu, Jung-Han;Shin, Soo-Sik;Ryu, Byung-Rok;Kim, Kyung-Sik;Jang, Jun-Ho;Oh, Ik-Hyun;Kim, Kap-Tae;Park, Hyun-Kuk
    • Journal of Powder Materials
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    • v.24 no.4
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    • pp.302-307
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    • 2017
  • In this study, Fe-Cu-C alloy is sintered by spark plasma sintering (SPS). The sintering conditions are 60 MPa pressure with heating rates of 30, 60 and $9^{\circ}C/min$ to determine the influence of heating rate on the mechanical and microstructure properties of the sintered alloys. The microstructure and mechanical properties of the sintered Fe-Cu-C alloy is investigated by X-ray diffraction (XRD) and field-emission scanning electron microscopy (FE-SEM). The temperature of shrinkage displacement is changed at $450^{\circ}C$ with heating rates 30, 60, and $90^{\circ}C/min$. The temperature of the shrinkage displacement is finished at $650^{\circ}C$ when heating rate $30^{\circ}C/min$, at $700^{\circ}C$ when heating rate $60^{\circ}C/min$ and at $800^{\circ}C$ when heating rate $90^{\circ}C/min$. For the sintered alloy at heating rates of 30, 60, and $90^{\circ}C/min$, the apparent porosity is calculated to be 3.7%, 5.2%, and 7.7%, respectively. The hardness of the sintered alloys is investigated using Rockwell hardness measurements. The objective of this study is to investigate the densification behavior, porosity, and mechanical properties of the sintered Fe-Cu-C alloys depending on the heating rate.

Optimum design on the lobe shapes of Gerotor Oil Pump (제로터 오일 펌프 로버형상에 관한 최적설계)

  • Kim Jae-Hun;Kim Chang-Ho;Kim Chul
    • Journal of the Korean Society for Precision Engineering
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    • v.23 no.4 s.181
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    • pp.124-131
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    • 2006
  • A gerotor pump is suitable for oil hydraulics of machine tools, automotive engines, compressors, constructions and other various applications. Especially the pump is an essential machine element of an automotive engine to feed lubricant oil. The subject of this paper is the theoretical analysis of internal lobe pump whose the main components are the rotors: usually the outer one is characterized by lobes with circular shape, while the inner rotor profile is determined as conjugate to the other. For this reason the first topic presented here is the definition of the geometry of the rotors starting from the design parameters. The choice of these parameters is subject to some limitations in odor to limit the pressure angle between the rotors. Now we will consider the design optimization. The first step is the determination of the instantaneous flow rate as a function of the design parameter. This allows us to calculate three performance indexes commonly used far the study of positive displacement pumps: the flow rate irregularity, the specific flow rate, and the specific slipping. These indexes are used to optimize the design of the pump and to obtain the sets of optimum design parameter. Results obtained from the analysis enable the designer and manufacturer of oil pump to be more efficient in this field, and the system could serve as a valuable one for experts and as a dependable training aid for beginners.