• 제목/요약/키워드: Rigidity analysis

검색결과 575건 처리시간 0.028초

고강도강 보강판의 극한강도에 관한 실험 (Experimental Investigations of Ultimate Strength for Siffened Plates with High-Strength Steel)

  • 황원섭;박완배;조은상
    • 한국강구조학회 논문집
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    • 제13권5호
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    • pp.457-466
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    • 2001
  • 본 연구는 고강도강(SM570, POSTEN80) 보강판의 거동특성을 실험을 토하여 검토한 것이다. 여기서는 압축력을 받는 총 7개의 보강판 시험체에 관한 재하실험결과를 정리하였으며, 이와 같은 실험결과를 기초로 하여 보강판 패널의 폭-두께비와 보강재의 강비에 관한 영향을 검토하였다. 또한 실험으로부터 구한 극한강도와 기준 내하력과의 비교를 통하여 보강판의 강도 특성에 관한 검토를 하였으며, 실험과 FEM 해석결과를 비교하였다.

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퀼형 공작기계구조물의 다단계 최적화(1) (정강성 해석 및 다목적함수 최적화) (Multi-Phase Optimization of Quill Type Machine Structures(1) (Static Compliance Analysis & Multi-Objective Function Optimization))

  • 이영우;성활경
    • 한국정밀공학회지
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    • 제18권11호
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    • pp.155-160
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    • 2001
  • To achieve high precision cutting as well as production capability in the machine tool, it is needed to develop excellent rigidity statically, dynamically and thermally as well. In order to predict the qualitative behavior of a machine tool, simultaneous analysis of mechanics and heat transfer is required. Generally, machine tool designers have solved designing problems based on partial estimation of the specified rigidity. This study clears the inter-relationship between therm, and propose multi-phase optimization of machine tool structure using a genetic algorithm. The multi-phase solution method is consists of a series of mechanical design problem. At this first phase of static design problem, multi-objective optimization for the purpose of minimization of the total weight and static compliance minimization is solved using the Pareto Genetic Algorithm.

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Probabilistic free vibration analysis of Goland wing

  • Kumar, Sandeep;Onkar, Amit Kumar;Manjuprasad, M.
    • International Journal of Aerospace System Engineering
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    • 제6권2호
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    • pp.1-10
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    • 2019
  • In this paper, the probabilistic free vibration analysis of a geometrically coupled cantilever wing with uncertain material properties is carried out using stochastic finite element (SFEM) based on first order perturbation technique. Here, both stiffness and damping of the system are considered as random parameters. The bending and torsional rigidities are assumed as spatially varying second order Gaussian random fields and represented by Karhunen Loeve (K-L) expansion. Here, the expected value, standard deviation, and probability distribution of random natural frequencies and damping ratios are computed. The results obtained from the present approach are also compared with Monte Carlo simulations (MCS). The results show that the uncertain bending rigidity has more influence on the damping ratio and frequency of modes 1 and 3 while uncertain torsional rigidity has more influence on the damping ratio and frequency of modes 2 and 3.

압연되는 스트립의 접촉 및 가공 응력에 대한 유한 요소 해석 (Finite Element Analysis on Contact and Work Stress of Rolled Strip)

  • 조재웅;한문식
    • 한국공작기계학회논문집
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    • 제17권2호
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    • pp.23-29
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    • 2008
  • This study analyzes the rolled circular rod strip with radius of loom and length of 350cm by using finite element analysis. The material strength and its durability of the rolled strip can be predicted through this study. As the penetration tolerance by contact decreases, the contact rigidity of strip increases. As the contact rigidity becomes the highest at the elapsed time of 1.2 second, the contact stress becomes the lowest. On the contrary, von-Mises stress becomes highest at this time. The total deformation on strip increases from the upper part of strip at the position near to rotating roll to the lower part of strip at the position near to fixing roll.

A Study on Asymmetrical Cost Behavior of Distribution Industry: Evidence from Korea

  • CHA, Sang-Kwon;CHOI, Yun-Yee
    • 유통과학연구
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    • 제18권11호
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    • pp.5-13
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    • 2020
  • Purpose: This research investigates the cost behavior of the distribution industry. Specifically, we investigate if the ratio of the increase in costs with an increase in sales is consistent with the ratio of the decrease in costs when sales decrease. Traditionally, cost is assumed to be symmetrical. In the case of the distribution industry, it was expected that the downward rigidity of the cost would be shown because it would be very difficult to decide to adjust resources when sales temporarily decrease. Therefore, studies have looked at Korean capital markets based on manufacturing and steel industries. However, no research has been done on the distribution industry. Research design, data, and methodology: To verify the hypothesis of this study, the asymmetry of cost was measured by Anderson et al. (2003). The sample used 28,695 firm-year data from 2002 to 2019 for the KOSPI and KOSDAQ stock markets. Results: The empirical analysis results are as follows. First, asymmetry of cost was observed in the case of the distribution industry. We confirm cost rigidity when sales decreased. Conclusions. This is the first study to look at cost behavior in the distribution industry, and the downward rigidity of cost in the distribution industry is observed.

Flexural performance of fire damaged and rehabilitated two span reinforced concrete slabs and beams

  • Yu, Jiang-Tao;Liu, Yuan;Lu, Zhou-Dao;Xiang, Kai
    • Structural Engineering and Mechanics
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    • 제42권6호
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    • pp.799-813
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    • 2012
  • Five two-span reinforced concrete (RC) slabs and seven two-span RC beams were tested under the ISO 834 standard fire with different durations. CFRP strengthening was then applied to some of the specimens after the damaged concrete was removed from the specimens and replaced with polymer mortar. All the specimens were loaded to failure to investigate the influence of fire-damage and the effectiveness of strengthening methods. Test results indicated that the flexural capacities of specimens decrease with the fire duration increases. Moreover, fire exposure had more significant effect on the flexural rigidity than on the bearing capacity of the specimens. After rehabilitation, the bearing capacities of specimens reached or even exceeded that of the reference RC specimen, and the strengthening methods seemed to have limited effect on flexural rigidity recovery. From the analysis of moment redistribution of tested beams, elevated temperature is found having different impacts on sagging moment region and hogging moment region. The damage of RC continuous member is definitely a comprehensive response of different regions.

심하부 복진 소견과 연관된 상한론, 금궤요략 수재 약물, 처방의 응용에 관한 연구 (Study on Application of the Herbal Medicines Mentioned in ${\ulcorner}$Sanghanron${\lrcorner}$, ${\ulcorner}$GeumGweyoryak${\lrcorner}$ with Regards to the abdominal Diagnoses Impressions of Epigastric Fullness and Rigidity)

  • 최명기;김준기
    • 동의생리병리학회지
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    • 제20권6호
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    • pp.1375-1387
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    • 2006
  • Through abdominal diagnoses, deficiency and excess, and cold and heat of the eight principles for differentiating syndromes can be determined, pathogens such as fluid retention, dry stool, retention of undigested food, abdominal mass, blood stagnation, stagnation of Gi, deficiency of Kidney Yang, and, spermatorrhea can be identified, nature and stages of the symptoms can be understood and then pathogenesis analyzed. Abdominal diagnosis can be one of primary factors in deciding treatment, expecting prognosis and treatment effect, and choosing herbal prescriptions. Representative herbs for epigastric stuffiness/fullness are Radix Ginseng, Pericarpium Citri, etc; for fullness of epigastrium, Rhizoma Pinelliae, Pericarpium Citri, Rhizoma Rhei, etc.; for severely rigid epigastrium, Radix Glycyrrhizae, Radix Ginseng, etc.; for epigastric pain, Rhizoma Pinelliae, Pericarpium Citri, etc.; for epigastric fullness and rigidity, Rhizoma Coptidis, Radix Ginseng, etc.; for feeling of obstruction in the epigastirum, Radix Bupleuri, Radix Ginseng, etc.; for palpitation in the epigastrium, Radix Glycyrrhizae, Ramulus Cinnamomi, etc. It is essential to rightly diagnose through comprehensive analysis of the data gained by the four methods of diagnosis, and in doing this, further studies on how to utilize abdomen diagnosis for clinical practice.

구기자 가지의 진동 특성 (Vibration Characteristics of Boxthorn (Lycium Chinense Mill) Branch)

    • 한국농업기계학회:학술대회논문집
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    • 한국농업기계학회 2001년도 동계 학술대회 논문집
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    • pp.292-309
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    • 2001
  • Modulus of elasticity, modulus of rigidity, damping ratio, and natural frequency of three varieties of boxthorn(Lycium chinense Mill) (Cheongyang #2, Cheongyang gugija, and Cheongyang native) branches were analyzed. Modulus of elasticity and modulus of rigidity of the boxthorn branch was determined using standard formula after simple beam bending and torsion test, respectively, using an universal testing machine. Damping ratio and natural frequency of branches were determined using a system consisted of an accelerometer, a PC equipped with A/D converter, and a software for data analysis. Relationship between the elastic modulus and branch diameter in overall varieties and branch types showed a good correlation (r$\cong$-0.81). There was, however, no correlation between torsional rigidity and branch diameter. The internal damping results were highly variable and the overall range of the damping ratio of the boxthorn branch was 0.014 -0.087, which indicated that the branch was a lightly damped structure. The natural frequency of the boxthorn branch was in the range of 89-363 rad/s for the overall varieties and branch types. A good correlation (r$\cong$0.82) existed between the natural frequency and branch diameter in overall varieties and branch type.

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타이타늄 상악 주연결장치에 디자인에 따른 주조성 및 견고성 비교 (COMPARISON OF RIGIDITY AND CASTABILITY IN DIFFERENT DESIGNS OF MAXILLARY MAJOR TITANIUM FRAMEWORK)

  • 이영재;방몽숙;양홍서;박상원;박하옥;임현필
    • 대한치과보철학회지
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    • 제45권4호
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    • pp.431-443
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    • 2007
  • Statement of problem: Injuries along with discomfort may result on the oral mucosa when non-rigid material is used as the major connector in construction of RPD, since nonrigid major connectors transmit unstable forces throughout the appliance. Titanium which recently draws attention as a substitute of Co-Cr had a difficulty in fabricating due to high melting temperature but the development of casting technique makes it possible to apply to the clinical case. Purpose: The purpose of this study was to investigate the rigidity and the castability of titanium upper major connector by design and make a comparison with Co-Cr major connectors which are widely used in clinical cases now. Material and methods: Casting was done using CP-Ti(Grage 2) (Kobe still Co., Japan) for the experimental groups, and 4 various designs namely palatal strap, U-shaped bar, A-P strap, and complete palatal plate were casted and 5 of each designs were included in each group. For the experimental group, Universal testing machine (Model 4502; Instron, Canton, Mass) was used to apply vertical torsional force vertically to the horizontal plane of major connector. In the second experiment, Vertical compressive force was applied to the horizontal plane of major connector. As a comparative group, Co-Cr major connector was equally manufactured and underwent the same experimental procedures Strain rate was measured after constant loading for one minute duration, and statistical analysis was done with SPSS ver.10.0 for WIN(SPSS. Inc. USA). From the one-way ANOVA and variance analysis (P=0.05), Scheffe's multiple comparison test implemented. Results: 1. Least amount of strain was observed with complete palatal plate followed by A-P bar, palatal bar, and the U-shaped bar having most amount of strain. 2. In all designs of titanium major connector, less strain rate was observed under compressive loading than under torsional loading showing more resistance to lateral force. 3. For titanium major connector, less strain rate was observed when the force is applied to the first premolar area rather than to the second molar area indicating more strength with shorter length of lever. 4. In Comparison of Co-Cr major connector with titanium major connector, palatal strap and U-shaped bar designs showed higher strength under torsional force that is statically significant, and under compressive force, no significant difference was observed expert for U-shaped bar. 5. In titanium major connector, complete palatal plate showed lowest success rate in casting when compared with the Co-Cr major connector. Conclusion: Above results prove that when using titanium for major connector, only with designs capable of generating rigidity can the major connector have almost equal amount of rigidity as Co-Cr major connector and show lower success rate in casting when compared with the Co-Cr major connector.

한반도 남부 지각평형과 암석권의 유효탄성두께 (On the isostasy and effective elastic thicness of the lithosphere in southern prt of the Korean Peninsula)

  • 최광선;김정희;신영홍
    • 지구물리
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    • 제5권4호
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    • pp.293-303
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    • 2002
  • 본 연구에서는 2002년까지 수집된 우리나라 일원의 각종 중력자료와 지형자료를 이용하여 한반도 남부지역(위도 $36.5^{\circ}N$, 경도 $127.5^{\circ}E$를 중심으로 하는 $332km{\times}332km$의 지역)에서 탄성판모델을 설정했을 때의 지각평형과 암석권의 탄성강도 및 유효탄성두께에 대하여 고찰해 보았다. 연구범위의 설정에 있어 이질적인 판구조환경을 가지고 있을 것으로 생각되는 동해의 영향을 배제하도록 하였다. 연구지역에서 파워스펙트럼분석에 의한 모호면의 평균깊이가 30km로 계산되었다. 지각을 단일층으로 가정하고 탄성판모델을 적용한 결과, 관측 코히어런스에서 짐이 300km이상의 파장을 가지면 거의 평형을 이루고 있고, 80km에서 300km 사이는 부분적으로 암석권의 강도에 의해 보상되고 있으며, 80km 이하의 파장의 경우는 거의 암석권의 강도에 의해 지지되고 있음이 나타난다. 지각모델과 강도를 가정하고 계산한 예측 코히어런스와 비교한 결과, 암석권의 탄성강도(flexural rigidity)는 $3.0{\times}10^{22}Nm$(유효탄성두께는 15km)로 나타났다. 이는 우리나라의 지각강도가 상당히 약하다는 것을 지시하며, 안정되고 오래된 지역에서 얻어진 결과보다는 해양이나 판의 경계부에서의 결과와 비슷하다. 우리나라의 경우 대규모의 지각변동과 그에 수반된 마그마의 관입이나 화산활동, 그리고 습곡과 단층 등의 영향은 암석권의 강도를 작게 만드는 원인으로 작용했을 것이다.

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