• Title, Summary, Keyword: cable stiffness

Search Result 183, Processing Time 0.036 seconds

Contact Stress Analysis of Stick Type Ignition Coil Jacket PET (Stick Type Ignition Coil Jacket PET의 접촉응력 해석)

  • Kim Yang-Sul
    • Journal of the Korean Society of Safety
    • /
    • v.20 no.1
    • /
    • pp.1-6
    • /
    • 2005
  • Stick type ignition coil is new development that connect directly with ECU(Electronic control unit), without needing a spark plug cable and distributor. Glass-fiber reinforced ploymeric composites provide the desirable properties of high stiffness and strength as well as low specific weight. Stick type ignition coil jacket is using PBT CF30 resin. PBT CF30 resin is a kind of electric insulation which is a superior engineering plastic that is used to prevent the leakage of the electrical current. If PET receive a mistake of design or excessive force when HV terminal oppress on jacket, it can happen to crack. Local stress concentrations occurring on the contact surface, the contact phenomenon becomes a direct cause to the wear and failure of mechanical structures. When it is cracked, it can allow a leakage of the electrical current. So, in this study, we analyze the contact stress to PBT jacket using ANSYS program, when HV terminal oppress on jacket. We suppose PBT to be Jacket and we analyzed contact stress that happens in PET like PBT analysis method. We compared the use of PBT and PET.

Analytical and numerical algorithm for exploring dynamic response of non-classically damped hybrid structures

  • Raheem, Shehata E. Abdel
    • Coupled systems mechanics
    • /
    • v.3 no.2
    • /
    • pp.171-193
    • /
    • 2014
  • The dynamic characterization is important in making accurate predictions of the seismic response of the hybrid structures dominated by different damping mechanisms. Different damping characteristics arise from the construction of hybrid structure with different materials: steel for the upper part; reinforced concrete for the lower main part and interaction with supporting soil. The process of modeling damping matrices and experimental verification is challenging because damping cannot be determined via static tests as can mass and stiffness. The assumption of classical damping is not appropriate if the system to be analyzed consists of two or more parts with significantly different levels of damping. The dynamic response of structures is critically determined by the damping mechanisms, and its value is very important for the design and analysis of vibrating structures. A numerical algorithm capable of evaluating the equivalent modal damping ratio from structural components is desirable for improving seismic design. Two approaches are considered to explore the dynamic response of hybrid tower of cable-stayed bridges: The first approach makes use of a simplified model of 2 coupled lumped masses to investigate the effects of subsystems different damping, mass ratio, frequency ratio on dynamic characteristics and equivalent modal damping; the second approach employs a detailed numerical step-by step integration procedure.

Mechanical performance and design optimization of rib-stiffened super-wide bridge deck with twin box girders in concrete

  • Wen, Xiong;Ye, Jianshu;Gai, Xuemei;Cai, C.S.
    • Structural Engineering and Mechanics
    • /
    • v.48 no.3
    • /
    • pp.395-414
    • /
    • 2013
  • The present study fundamentally investigated the mechanical performance of the rib-stiffened super-wide bridge deck with twin box girders in concrete, which is a very popular application to efficiently widen the bridges with normal span. The shear lag effects of the specific cross-sections were firstly studied. The spatial stress distribution and local stiffness of the bridge deck with twin box girders were then investigated under several typical wheel load conditions. Meanwhile, a comparative study for the bridge deck with and without stiffening ribs was also carried out during the investigation; thereby, a design optimization for the stiffening ribs was further suggested. Finally, aiming at the preliminary design, an approximate methodology to manually calculate the bending moments of the rib-stiffened bridge deck was analytically proposed for engineers to quickly assess its performance. This rib-stiffened bridge deck with twin box girders can be widely applied for concrete (especially concrete cable-stayed) bridges with normal span, however, requiring a super-wide bridge width due to the traffic flow.

Flutter analysis of long-span bridges using ANSYS

  • Hua, X.G.;Chen, Z.Q.;Ni, Y.Q.;Ko, J.M.
    • Wind and Structures
    • /
    • v.10 no.1
    • /
    • pp.61-82
    • /
    • 2007
  • This paper presents a novel finite element (FE) model for analyzing coupled flutter of long-span bridges using the commercial FE package ANSYS. This model utilizes a specific user-defined element Matrix27 in ANSYS to model the aeroelastic forces acting on the bridge, wherein the stiffness and damping matrices are expressed in terms of the reduced wind velocity and flutter derivatives. Making use of this FE model, damped complex eigenvalue analysis is carried out to determine the complex eigenvalues, of which the real part is the logarithm decay rate and the imaginary part is the damped vibration frequency. The condition for onset of flutter instability becomes that, at a certain wind velocity, the structural system incorporating fictitious Matrix27 elements has a complex eigenvalue with zero or near-zero real part, with the imaginary part of this eigenvalue being the flutter frequency. Case studies are provided to validate the developed procedure as well as to demonstrate the flutter analysis of cable-supported bridges using ANSYS. The proposed method enables the bridge designers and engineering practitioners to analyze flutter instability by using the commercial FE package ANSYS.

Buffeting Response Correction Method based on Dynamic Properties of Existing Cable-Stayed Bridge (공용 사장교의 동적특성을 반영하는 버페팅 응답보정법)

  • Kim, Byeong Cheol;Yhim, Sung Soon
    • Journal of The Korean Society of Civil Engineers
    • /
    • v.33 no.1
    • /
    • pp.71-80
    • /
    • 2013
  • According to design specifications for structural safety, a bridge in initial design step has been modelled to have larger self-weight, external loads and less stiffness than those of real one in service. Thereby measured buffeting responses of existing bridge show different distributions from those of the design model in design step. In order to obtain accurate buffeting responses of the in-site bridge, the analysis model needs to be modified by considering the measured natural frequencies. Until now, a Manual Tuning Method (MTM) has been widely used to obtain the Measurement-based Model(MBM) that has equal natural frequencies to the real bridge. However, since state variables can be selected randomly and its result is not apt to converge exact rapidly, MTM takes a lot of effort and elapsed time. This study presents Buffeting Response Correction Method (BRCM) to obtain more exact buffeting response above MTM. The BRCM is based on the idea the commonly used frequency domain buffeting analysis does not need all structural properties except mode shapes, natural frequencies and damping ratio. BRCM is used to improve each modal buffeting responses of the design model by substituting measured natural frequencies. The measured natural frequencies are determined from acceleration time-history in ordinary vibration of the real bridge. As illustrated examples, simple beam is applied to compare the results of BRCM with those of a assumed MBM by numerical simulation. Buffeting responses of BRCM are shown to be appropriate for those of in-site bridge and the difference is less than 3% between the responses of BRCM and MTM. Therefore, BRCM can calculate easily and conveniently the buffeting responses and improve effectively maintenance and management of in-site bridge than MTM.

Experimental and Analytical Studies on the Non-Linear behaviors of Pre-Stressed Steel H-Beams (프리스트레스트 H형강 거더의 비선형 거동에 대한 실험적 및 이론적 연구)

  • Kim, Moon-Young;Kim, Nak-Kyung;Oh, Yong-Hwan
    • Journal of the Computational Structural Engineering Institute of Korea
    • /
    • v.32 no.6
    • /
    • pp.359-366
    • /
    • 2019
  • Experimental and analytical studies on the behavioral characteristics of a pre-stressed (PS) steel girder are conducted to investigate the effects of deviators on the non-linear inelastic properties of the PS system. In this regard, 4 test specimens consisting of a steel H-beam, a straight cable with eccentricity, anchorages, and deviators are built and failure tests are performed under two-point loading. In addition, in-plane elastic deformation theories for the PS system without a deviator, and with three deviators at regular intervals are analytically formulated and solved using a symbolic calculation technique. To verify the validity of the experimental and the proposed analytical theories, the results obtained using FEM models composed of beam elements, rigid beam elements, and truss cable elements, are compared to the experimental results and the analytical solutions. As a result, it is determined that externally installed un-bonded deviators inhibit flexural deformation of the deformed beam to such an extent that their elastic stiffness, and failure strength are significantly improved compared to those of the PS system without deviators.

TETANUS TRISMUS ASSOCIATED WITH FACIAL ELETRICAL BURN (전기화상 환자에서 나타난 파상풍-증례보고)

  • Ha, Tae-Young;Kang, Jin-Han;Shin, Mee-Ran;Ahn, Byoung-Keun;Kim, Mi-Ja
    • Journal of the Korean Association of Oral and Maxillofacial Surgeons
    • /
    • v.32 no.4
    • /
    • pp.380-383
    • /
    • 2006
  • Tetanus is rare in Korea due to the introduction of vaccination programs and the advancement in public health. Its common signs are trismus, voice disturbance, neck stiffness, and difficulty in swallowing, etc. A 56 years old man was injured by grasping a high voltage electric cable. After the accident, he fell down on a steel plate and had a head trauma. When he visited Emergency Department, there was multiple electric burn wound on left arm and left facial area. He was hospitalized on a department of neurosurgery, because intra cranial hemorrhage was presumed. 12 days later, he was referred to department of OMFS with developed painful masseter spasms and trismus. That night he violently bit his tongue with his denture. Because masseter muscle and temporal muscle constriction was involuntary, tongue was lacerated and denture was distorted. At first we supposed that the symptom was related with neurologic disturbance following head trauma or electric shock. But it was revealed that trismus was caused by tetanus on an electrophysiological test. By using mechanical ventilation and administration of tetanus immunoglobulin, muscle-relaxant, and sedatives at ICU, symptoms had subsided (4-weeks). Because tetanus is rare disease, we rarely suppose tetanus infection to be a cause of a trismus. Especially it is more difficult to diagnose in patient who has head trauma, burn and neurologic problem as in this case.

Structural Analysis Modeling of Disaster Resilient Greenhouse Structures (내재해형 온실구조의 해석을 위한 구조모델)

  • Jung, Ji-Eun;Kim, Dae-Jin;Kim, Hong-Jin;Shin, Seung-Hoon;Kim, Jin-Won
    • Journal of the Computational Structural Engineering Institute of Korea
    • /
    • v.30 no.1
    • /
    • pp.7-15
    • /
    • 2017
  • This paper presents the results of the parametric study to investigate the effects of several analysis modeling parameters such as support conditions, member connectivities and cable member stiffness on the main mode shapes and natural frequencies of a representative disaster resilient greenhouse structure. In addition, an ambient vibration test was performed on the representative greenhouse structure and its main mode shapes and natural frequencies were obtained. By comparing the experimental and analysis results, a proper analysis modeling method of the representative greenhouse structure was proposed.

Structural identification of Humber Bridge for performance prognosis

  • Rahbari, R.;Niu, J.;Brownjohn, J.M.W.;Koo, K.Y.
    • Smart Structures and Systems
    • /
    • v.15 no.3
    • /
    • pp.665-682
    • /
    • 2015
  • Structural identification or St-Id is 'the parametric correlation of structural response characteristics predicted by a mathematical model with analogous characteristics derived from experimental measurements'. This paper describes a St-Id exercise on Humber Bridge that adopted a novel two-stage approach to first calibrate and then validate a mathematical model. This model was then used to predict effects of wind and temperature loads on global static deformation that would be practically impossible to observe. The first stage of the process was an ambient vibration survey in 2008 that used operational modal analysis to estimate a set of modes classified as vertical, torsional or lateral. In the more recent second stage a finite element model (FEM) was developed with an appropriate level of refinement to provide a corresponding set of modal properties. A series of manual adjustments to modal parameters such as cable tension and bearing stiffness resulted in a FEM that produced excellent correspondence for vertical and torsional modes, along with correspondence for the lower frequency lateral modes. In the third stage traffic, wind and temperature data along with deformation measurements from a sparse structural health monitoring system installed in 2011 were compared with equivalent predictions from the partially validated FEM. The match of static response between FEM and SHM data proved good enough for the FEM to be used to predict the un-measurable global deformed shape of the bridge due to vehicle and temperature effects but the FEM had limited capability to reproduce static effects of wind. In addition the FEM was used to show internal forces due to a heavy vehicle to to estimate the worst-case bearing movements under extreme combinations of wind, traffic and temperature loads. The paper shows that in this case, but with limitations, such a two-stage FEM calibration/validation process can be an effective tool for performance prognosis.

Proposition of Improved Semi-Analytical Relationship considering Response Characteristics of Buried Pipeline (지중매설관로의 거동특성을 반영한 개선된 해석적 관계식의 제안)

  • 김태욱;임윤묵;김문겸
    • Journal of the Earthquake Engineering Society of Korea
    • /
    • v.7 no.5
    • /
    • pp.37-46
    • /
    • 2003
  • Response analysis of buried pipeline subjected to permanent ground deformation(PGD) due to liquefaction is mainly executed by use of numerical analysis or semi-analytical relationship, Especially for the semi-analytical relationship considering transverse PGD, it has somewhat limited applicability : since it has different formula according to the width of PGD and does not reflect various patterns of PGD which is caused by the decrease of soil stiffness, Therefore, in this study, the applicability of existing analytical relationship is closely investigated through the comparison of FEM results at first. And then, based on meaningful contemplation, improved analytical relationship is proposed. The proposed one models the system behavior of buried pipeline as the combination of cable and beam, and thus it is applicable to arbitrary width of PGD, Moreover, it does reflect various patterns of PGD by introducing interaction pattern coefficient. Through the comparison of numerical results using the FEM and the proposed analytical relationship, rational applicability is objectively verified and noticeable considerations are discussed, Moreover, analyses considering the change of PGD magnitude and patterns are performed.