• Title, Summary, Keyword: neutral axis

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Surface effects on nonlinear vibration and buckling analysis of embedded FG nanoplates via refined HOSDPT in hygrothermal environment considering physical neutral surface position

  • Ebrahimi, Farzad;Heidari, Ebrahim
    • Advances in aircraft and spacecraft science
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    • v.5 no.6
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    • pp.691-729
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    • 2018
  • In this paper the hygro-thermo-mechanical vibration and buckling behavior of embedded FG nano-plates are investigated. The Eringen's and Gurtin-Murdoch theories are applied to study the small scale and surface effects on frequencies and critical buckling loads. The effective material properties are modeled using Mori-Tanaka homogenization scheme. On the base of RPT and HSDPT plate theories, the Hamilton's principle is employed to derive governing equations. Using iterative and GDQ methods the governing equations are solved and the influence of different parameters on natural frequencies and critical buckling loads are studied.

An Experimental Study on Flexural Strength of SC Composite Beams Enforced by Unbonded Post Tension (비부착 포스트텐션 SC합성보의 휨내력에 관한 실험적 연구)

  • Kim, Heui Cheol;Ahn, Hyung Joon;Ryu, Soo Hyun
    • Journal of Korean Society of Steel Construction
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    • v.21 no.2
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    • pp.135-144
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    • 2009
  • This study aims to suggest an appropriate flexural reinforcement technique by evaluating the reinforcement capacity of specimens that underwent flexural reinforcement according to the post-tension method with the anchoring position of an unbonded tension member on the conventional SC composite beam and the applied tension level as variables. For the experiment, up to a predetermined yield load was applied to each type of specimen and then, unbounded post-tensioning was additionally conducted to examine its reinforcement capacity. The analysis of the said experiment showed that the post-reinforced SC composite beam was characterized by significantly improved yield stress and initial stiffness, compared with the pre-reinforced one and the experimental measurements/theoretical values of maximum stress ranged from 0.95 to 1.13 following reinforcement. There was little or no change depending on the maximum stress and tension in the specimen (D160, Class 240) whose neutral axis and upper part had anchoring devices mounted prior to reinforcement. Rather, the ductility decreased with the increasing tension. On the contrary, in the case of the other specimen (Class D120) whose neutral axis had anchoring devices mounted after reinforcement, both the maximum stress and ductility increased with increasing tension, which indicates that the latter tension reinforcement was reasonably appropriate and effective for the neutral axis reinforcement.

Wide Air-gap Control for Multi-module Permanent Magnet Linear Synchronous Motors without Magnetic Levitation Windings

  • Bang, Deok-Je;Hwang, Seon-Hwan
    • Journal of Power Electronics
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    • v.16 no.5
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    • pp.1773-1780
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    • 2016
  • This paper proposes a wide air-gap control method for the multi-module permanent magnet linear synchronous motor (MM-PMLSM) based on independent vector control. In particular, the MM-PMLSM consists of symmetrical multi-module and multi-phase structures, which are basically three-phase configurations without a neutral point, unlike conventional three-phase machines. In addition, there are no additional magnetic levitation windings to control the normal force of the air-gap between each stator and mover. Hence, in this paper, a dq-axis current control applying a d-q transformation and an independent vector control are proposed for the air-gap control between the two symmetric stators and mover of the MM-PMLSM. The characteristics and control performance of the MM-PMLSM are analyzed under the concept of vector control. As a result, the proposed method is easily implemented without additional windings to control the air-gap and the mover position. The effectiveness of the proposed independent vector control algorithm is verified through experimental results.

A LONGITUDINAL STUDY ON THREE FACIAL GROWTH PATTERNS IN KOREANS WITH NORMAL OCCLUSION (정상교합자의 3가지 안면골 성장양상에 관한 누년적 연구)

  • Park, Krung-Duk;Sung, Jae-Hyun
    • The korean journal of orthodontics
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    • v.25 no.3
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    • pp.273-286
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    • 1995
  • The purpose of this study was to compare the difference of the growth aspects in three facial growth patterns. The biennial serial cephalometric radiographs of 33 samples(19males, 14females) with normal occlusion from 8.5 years to 18.5 yews of age were used in this study. The facial growth patterrn was categorized in 3 types(Drop type, Neutral type, Forward type) by the total amounts of the Y-axis which changed from 8.5 years to 18.5 years of age. The growth change of the craniofacial area during 10 years in each growth type was analyzed and was compared among the 3 growth types. The results of this study might be summarized as follows. 1. The samples that were classified by total change of the Y-axis during this study period were distributed to 52% of the neutral type, 27% of the forward type, 21% of the drop type. 2. The anterior growth of the maxilla to the cranial base(N per A) showed larger in the forward type than in other 2 types(p<0.05). 3. The palatal plane to the FH plane showed more anterior-superior inclination in the forward type with age during this study period. 4. The anterior growth of the mandible to the cranial base(N per Pog) appeared large in rank order, of largest the forward type, second the neutral type, and third the drop type(p<0.05). 5. During this study period the mandibular plane(SN/MN,FMA) showed more counterclockwise rotation in the forward type than in the drop type(p<0.05), and this tendency was stronger in males than in females(p<0.05). 6. The growth of the mandibular corpus length(Go-Me) showed smaller in the drop type than in the other 2 types(p<0.05). 7. In the forward type and the neutral type, the anterior growth of the mandible was larger than that of the maxilla(p<0.05). 8. In the craniofacial growth distances and angulations turned out to be somewhat variable, but the vertical proportion had a strong tendency whose original relation was maintained consistently during this study period. 9. Through these analyzed data, the profilograms on each growth type were constructed to evaluate individual growth pattern in the orthodontic diagnosis.

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A Longitudinal change of ODI and APDI on Three Facial Growth Patterns in Koreans with Normal Occlusion (정상 교합자의 세가지 안면 성장유형에 따른 ODI, APDI의 변화)

  • Lee, Sun-Reong;Park, Kyung-duk;Kyung, Hee-Moon;Sung, Jae-Hyun
    • The korean journal of orthodontics
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    • v.26 no.5
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    • pp.557-568
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    • 1996
  • The purpose of this study was to analyze the growth changes of ODI and APDI with age on the three facial growth patterns. The biennial serial cephalometric radiographs of 19 male and 14 famale samples with normal occlusion during 10 years were used in this study. The samples were divided into three groups - drop type, neutral type, forward type - by the total change of the Y-axis during the periods of the study. The findings in this investigation indicated the following: 1. The mean values and standard deviations of each age group in each facial type of male and famale were obtained. 2. The difference of ODI and APDI among the 3 facial types was not significant through all observed ages(P)0.05). The size of ODI appeared large consistently in order of the drop, neutral, and forward type in both male and female through all observed ages. 3. The ODI and APDI were maintained without any charges with age during the periods of the study(p>0.05). 4. In correlation analysis between the total change of the Y-axis and 6 measurements, the AB plane angle and facial angle showed correlation in both male and female(p<0.05), the APDl in only female(p<0.001), but the ODI not appeared correlation in either male or female(p>0.05).

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An Experimental Investigation on the Bond Characteristics of Reinforced Concrete Structure (철근 콘크리트 부재의 부착거동에 관한 실험적 연구)

  • 오병환;이성로;방기성
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.122-127
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    • 1990
  • The transfer of forces across the interface by bond between concrete and steel is of fundamental importance to many aspects of reinforced concrete behavior. Bond stress - slip relationships were studied using a symmetrical tension test specimen. This type of test is intented to simulate conditions in the tension zone of a concrete beam between primary cracks and below the neutral axis. These relationships between local bond stress and local slip are quite different at different locations along the bar. The present study allows more accurate analysis of reinforced concrete structures by employing more realistic bond stress-slip relations.

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Behavior Prediction of Strengthened! Reinforced! Concrete Beam using Nonlinear Analysis (비선형 해석을 통한 보강된 RC 보의 거동 예측)

  • 박중열;황선일;조홍동;한상훈
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.561-566
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    • 2003
  • In this study, to predict the behavior of RC beam strengthened with Carbon fiber reinforced polymer(CFRP) plate, analytical program considering material non-linearity is developed. Strain compatibility and force equilibrium are applied and internal forces of constitutive material are calculated using nonlinear stress-strain relationship. Also, to certainty the reliability of analytical program, deflection, strain of CFRP plate, change of neutral axis on cross section and crack distribution at failure are compared with those of experiment, and each results are almost coincident.

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Parametric Study about Measuring Train Loads (열차하중 측정에 관한 매개변수 연구)

  • Lee So-Jin;Oh Ji-Taek;Park Ok-Jeoung
    • Proceedings of the KSR Conference
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    • pp.1148-1154
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    • 2004
  • Parametric studies are executed by numerical method varying then number of strain gauges, rail section and distance of sleeper from which the followings are obtained. Wheel forces or lateral forces are measured by connecting eight strain gauges on rail to single Wheatstone bridge. The method eliminates the influence of interaction and measured stability. Strain gauges are fastened on the neutral axis of the rail so as not to be influenced by sleeper.

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In vivo 3D Kinematics of Axis of Rotation in Malunited Monteggia Fracture Dislocation

  • Kim, Eugene;Park, Se-Jin;Jeong, Haw-Jae;Ahn, Jin Whan;Shin, Hun-Kyu;Park, Jai Hyung;Lee, Mi Yeon;Tsuyoshi, Murase;Sumika, Ikemototo;Kazuomi, Sugamoto;Choi, Young-Min
    • Clinics in Shoulder and Elbow
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    • v.17 no.1
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    • pp.25-30
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    • 2014
  • Background: Normal elbow joint kinematics has been widely studied in cadaver, whilst in vivo study, especially of the forearm, is rare. Our study analyses, in vivo, the kinematics of normal forearm and of malunited forearm using a three-dimensional computerized simulation system. Methods: We examined 8 patients with malunited Monteggia fracture and 4 controls with normal elbow joint. The ulna and radius were reconstructed from CT data placing the forearm in three different positions; full pronation, neutral, and full supination using computer bone models. We analyzed the axis of rotation 3-dimentionally based on the axes during forearm rotation from full pronation to full supination. Results: Axis of rotation of normal forearm was pitch line, with a mean range of 2 mm, from full pronation to full supination, connecting the radial head center proximally and ulnar fovea distally. In normal forearm, the mean range was 1.32 mm at the proximal radioulnar joint and 1.51 mm at the distal radioulnar joint. However in Monteggia fracture patients, this range changed to 7.65 mm at proximal and 4.99 mm at distal radoulnar joint. Conclusions: During forearm rotation, the axis of rotation was constant in normal elbow joint but unstable in malunited Monteggia fracture patients as seen with radial head instability. Therefore, consideration should be given not only to correcting deformity but also to restoring AOR by 3D kinematics analysis before surgical treatment of such fractures.