• Title/Summary/Keyword: Unbalance mass

Search Result 154, Processing Time 0.024 seconds

Analyses on Aerodynamic and Inertial Loads of an Airborne Pod of High Performance Fighter Jet (고기동 항공기 하부 장착 파드의 공력 및 관성하중 분석 연구)

  • Lee, Jaein;Shin, Jinyoung;Cho, Donghyun;Jung, Hyeongsuk;Choi, Taekyu;Lee, Jonghoon;Kim, Youngho;Kim, Sitae
    • Journal of the Korea Institute of Military Science and Technology
    • /
    • v.25 no.1
    • /
    • pp.9-22
    • /
    • 2022
  • A fighter performing a reconnaissance mission is equipped with a pod that drives optical/infrared sensors for acquiring and identifying target information on the lower part of the fuselage. Due to the nature of the reconnaissance mission, the fighter performs high speed evasive maneuvers, and the resulting load should be considered importantly for the development of the pod. This paper concerns a numerical investigation into the inertial and aerodynamic loads of the airborne pod of high performance aircrafts. For the aerodynamic load analysis, the pylon and pod shapes are added to the fighter 3D model, and the commercial software was used for static and dynamic analysis. Considering the practical mission conditions, the common/extreme conditions were established respectively in the static and dynamic situations of pods and the driving torque could be tripled under dynamic conditions. In the analysis of inertia load, a 3-DOF model considering roll and turning maneuvers was derived by the Lagrangian method, and then the numerical integration method was applied to the analysis. As a results, it was conformed that the inertia load was generally induced at a low level compared to the aerodynamic load, but depending on the unbalance mass condition of the pod, the inertia load cannot be negligible.

Yaw Gearbox Design for 4MW Class Wind Turbine (4MW급 풍력발전기용 요 감속기 설계)

  • Lee, Hyoung-Woo;Kim, In-Hwan;Lee, Jae-Shin
    • Journal of Convergence for Information Technology
    • /
    • v.12 no.2
    • /
    • pp.142-148
    • /
    • 2022
  • In this paper, the weight reduction design of the yaw gearbox for wind turbine was performed through the finite element analysis method, and the stability was checked by performing the critical speed analysis. The weight reduction product can improve engine efficiency, save parts materials, and earn economic benefits. The yaw gearbox is lightweighted with the goal of achieving a safety rate of 1.3 or higher for wind turbine as indicated by IEC61400-1. In order to reduce the weight of the carrier, a topology optimization method was performed. The safety factor was verified by performing finite element analysis on the carrier. In addition, the housing and carrier were modeled using the finite element method, and the gear train was modeled using MASTA. For the yaw gearbox, the housing and carrier FE model and the gear train model were connected by the partial structural synthesis method to perform the rotational vibration analysis. Vibration excitation sources are mass unbalance and gear mesh frrequemcy, and as a result of the critical speed analysis, it was found that there was no resonance within the operating speed range.

Rotordynamic Analyses of a Composite Roller for Large LCD Panel Manufacturing (대형 LCD 패널 제조용 복합재 롤러의 회전체 동역학 해석)

  • Park, Hyo-Keun;Choi, Jin-Ho;Kweon, Jin-Hwe;Lee, Young-Hwan;Yang, Seung-Un;Kim, Dong-Hyun
    • Composites Research
    • /
    • v.19 no.6
    • /
    • pp.8-15
    • /
    • 2006
  • In this study, computational rotor dynamic analyses of a composite roller used for large LCD panel manufacturing process have been conducted. The present computational method is based on the general finite element method with rotating gyroscopic effects of rotor systems. General purpose commercial finite element code, SAMCEF which has special rotordynamics analysis module is applied. For the purpose of numerical verification, comparison study for a benchmark dual rotor model with support bearings is also presented. Detailed finite element models for composite roller with optimized lamination angles are constructed and analyzed considering gravity effect in order to investigate vibration characteristics in actual operation environment. As results of the present study, rotor stability diagrams and mass unbalance responses are presented for different rotating conditions.

Treatment of Skin Diseases in Hyungsang Medicine (피부병의 형상의학적 치료)

  • Suk Min He;Hwang Won Duek;Jung Haeng Gyu;Lee Yong Tae
    • Journal of Physiology & Pathology in Korean Medicine
    • /
    • v.18 no.3
    • /
    • pp.646-669
    • /
    • 2004
  • By treating skin diseases with Hyungsang medicine and reviewing the clinical cases of them through classifying skin diseases into general care and into Hyungsang medical care, the writer came to the conclusion as followings. The skin is a house of Kyungnak, and it' s a place which Ki comes in and out, which human body controls conditions of his physiological function and which doctors can make a diagnosis from seeing it. The skin is subject to lung and large intestine in the point of organ, but in the point of movement, to spleen and stomach. Skin diseases come from unbalance of Ki and Hyul, mostly from fever in blood and also from Dam, Wind, Dampness and Dryness because of including fire. Generally skin diseases are treated according to classifying into distinctive symptoms, region, cause or time being occurred, and concomitant symptoms. After being divided into man and woman, age and youth, fatness and leanness, Jung Ki Shin Hyul type, visceral figures, Yukkyung shapes on Hyungsang medicine method, the remedy of skin diseases which is combined common meditation with Hyungsang medical method is efficacious. In distinguishing into man and woman, age and youth, man gets sick mainly by drinking liquor and exhausting Jung, woman is taken ill generally by indigestion and Damwha, especially by drinking liquor. Young child gets ill mostly from inherent weakness, but in many cases he is occurred by disturbed digestion, so he must be taken care of ingesting food. The aged becomes ill from weakening, so he must be treated according to reasons of diseases. To fatness and leanness, skin diseases are showed symptoms by weakened Yang, insufficient Yin or excess fever on the theory of upper and lower parts, by unbalance of Ki and Hyul on the theory of left and right, by Dryness and Dampness on the theory of front and rear and by insufficiency of vitality and combined fever on the theory of inside and outside. Therefore doctors must cure the symptoms according to the theory of upper and lower, left and right, front and rear and inside and outside. In type of Jung Ki Shin Hyul, the balances between Jung-Hyul and Shin-Ki are important points. Concretely Jung type comes to easily shortage of Jung or gathering abnormally Dampness and Dam, Ki type is easy to make a mass with Ki or to be deficient of Ki, Shin type comes to press seven emotions togather or to be insufficient of Yin and fever inside, and Hyul type is inclined to be deficient of Hyul and to become feverish or to be deficient of Ki. Therefore on the ground of the above reasons skin diseases come into existence. Inclusively in Jung-Hyul type , Ki must be moved on the base of full Jung-Hyul, so Wukmijiwhangtang or Samultang is prescribed basically. In Shin-Ki type , Jung-Hyul is saved on the base of moving Ki, so Hyangsosan or Yijintang is the proper prescription. Considering the visceral figures, doctors judge for diagnosis and remedy by putting together the elements, that is, great and small sizes of a set of features (eye, ear, mouth, nose), color and temper. The yukkyung types are classified according to many or few of Ki-Hyul, and then skin diseases appear by being inclined toward one side between Ki and hyul, or among the six atmospheric elements(wind, cold, heat, dampness, dryness, and fire). Especially because Yangmyung type is full of much Ki and Hyul, and also has much fever in stomach, he gets skin symptoms frequently. So his prescription is based on taking off fever in stomach, and also he must be careful about regimen certainly.