• 제목/요약/키워드: Static Strength Test

검색결과 780건 처리시간 0.037초

철도 강화노반재료의 정ㆍ동적 특성 분석 (Analysis of Static and Dynamic Characteristics of Reinforced Roadbed Materials)

  • 황선근;신민호;이성혁;이시한;최찬용
    • 한국철도학회논문집
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    • 제3권1호
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    • pp.34-41
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    • 2000
  • The analysis of static and dynamic characteristics of reinforced roadbed materials was performed through model and laboratory tests. The strength characteristic of reinforced roadbed materials such as HMS-25 and soil were investigated through the unconfined axial compression test, the model soil box test and the combined resonant column and torsional shear test. The unconfined axial compression strength of HMS-25 shows a steady increasement in strength due to the chemical hardening reaction between HMS-25 and water. The result of model soil box test reveals that railroad roadbed of HMS-25 is better than that of soil in several aspects, such as, bearing capacity and settlement. The combined resonant column and torsional shear test result indicates that shear modulus of HMS-25 and soil increase with the power of 0.5 to the confining pressure and linear relationship to normalized shear modulus and damping ratio.

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기능적 근력강화 운동이 뇌성마비 아동의 기립균형에 미치는 영향 (The Effect of Functional Strengthening Exercise of Standing Balance in a Child With Cerebral Palsy)

  • 신화경;정보인
    • 한국전문물리치료학회지
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    • 제8권3호
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    • pp.97-105
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    • 2001
  • The purpose of this study was to investigate the effect of functional strengthening exercise on static and dynamic standing balance in a child with cerebral palsy. The subject was a 7 year old boy with diplegia whose Gross Motor Function Measure (GMFM) score was 80% along with G1 of the lower extremities in Modified Ashworth Scale. The subject was ambulatory with some degree of limitation and demonstrated muscle weakness and strength asymmetry in the lower extremities. A changing criterion design for a single-subject research was used for this study. The functional strengthening exercise consisted of lower extremity ergometer exercise and knee exercise with grading movement in standing position, each for 20 minutes, which lasted 18 sessions for 6 weeks. A knee extensor strength test on both extremities and standing balance test were conducted after each functional strengthening exercise. Two types of standing balance were tested: one leg stance test and functional reach test. One leg stance test was to evaluate static standing balance, and functional reach test was to evaluate dynamic standing balance. The results showed that the functional strengthening exercise had some positive effects on improvement of both static and dynamic standing balance, and there was a positive correlation between the knee strength and standing balance.

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Aging 효과에 따른 낙동강 모래의 비배수 전단거동 특성 (Characteristics of Undrained Shear Behavior for Nak-Dong River Sand Due to Aging Effect)

  • 김영수;김대만
    • 한국지반공학회:학술대회논문집
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    • 한국지반공학회 2005년도 춘계 학술발표회 논문집
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    • pp.916-923
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    • 2005
  • In this study, to observe aging effect of undrained shear behavior for Nak-Dong River sand, undrained static and cyclic triaxial tests were performed with changing relative density ($D_r$), consolidation stress ratio($K_c$) and consolidation time. As a result of the test, the modulus of elasticity to all samples estimated within elastic zone by the micro strain of about 0.05% in case of static shear behavior increased with the lapse of consolidation time significantly, so aging effect was shown largely. Also strength of phase transformation point(S_{PT}$) and strength of critical stress ratio point($S_{CSR}$) increased with the lapse of consolidation time. Undrained cyclic shear strength($R_f$) obtained from the failure strain 5% increased in proportion to relative density($D_r$) and initial static shear stress($q_{st}$), $R_f$ of consolidated sample for 1,000 minutes increased about 10.6% compared to that for 10 minutes at the loose sand, and $R_f$ increased about 7.0% at the medium sand. In situ application range of $R_f$ to the magnitude of earthquake for Nak-Dong River sand was proposed by using a increasing rate of $R_f$ as being aging effect shown from this test result.

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신형 경전철차량 대차프레임 하중시험 방법 및 결과 고찰 (A Study on The Load Test Method and Result For Bogie Frame of New LRT)

  • 김원경;원시태;전창성
    • 한국철도학회:학술대회논문집
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    • 한국철도학회 2008년도 추계학술대회 논문집
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    • pp.1679-1688
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    • 2008
  • Recently, the bogie frame weight of Light Rail Transit system has been reduced in order to save energy and materials. However, this light weighted vehicle structure is very important to verify the fatigue strength at the development stage. Bogie system consists of bogie frame, suspensions, wheel-sets, braking system and transmission system. Among these components, the bogie frame is most significant component subjected to the whole vehicle and passenger loads. In this study, the bogie frame for the New LRT power car is evaluated to the static and fatigue strength. And the evaluation method is used the LRT Performance Test Standards Specification throughout the FEM analysis and static load test. The static and fatigue test results for the LRT bogie frame of power car has been appeared very safety and stable for the design load conditions.

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달착륙선 충격흡수장치용 알루미늄 허니콤의 Crush Strength에 관한 연구 (Study of Crush Strength of Aluminum Honeycomb for Shock Absorber of Lunar Lander)

  • 김신;이혁희;김현덕;박정선;임재혁;황도순
    • 항공우주시스템공학회지
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    • 제4권3호
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    • pp.1-5
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    • 2010
  • Understanding the crushing behaviour of aluminum honeycombs under dynamic loading is useful for crash simulations of vehicles and for design of impacting energy absorbers. In the study of honeycomb crushing under quasi-static, dynamic loading, the most important parameter is crush strength. Crush strength is indicated to energy absorption characteristic of aluminum honeycomb. In this study, Using Finite Element Analysis carried out crush strength of hexagonal aluminum honeycomb then the results was compared with Quasi-static test. Consequently, Crush strength is different in quasi-static loading and dynamic loading about 16%.

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온도와 재령이 콘크리트의 동탄성계수와 정탄성계수의 상관관계에 미치는 영향 (Effect of Temperature and Aging on the Relationship between Dynamic and Static Elastic Modulus of Concrete)

  • 한상훈;김진근
    • 한국콘크리트학회:학술대회논문집
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    • 한국콘크리트학회 2001년도 가을 학술발표회 논문집
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    • pp.445-450
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    • 2001
  • The paper investigates the relationships between dynamic elastic modulus and static elastic modulus or compressive strength according to curing temperature, aging, and cement type. Based on this investigation, the new model equations are proposed. Impact echo method estimates the resonant frequency of specimens and uniaxial compression test measures the static elastic modulus and compressive strength. Type I and V cement concretes, which have the water-cement ratios of 0.40 and 0.50, are cured under the isothermal curing temperature of 10, 23, and 50 $^{\circ}C$. Cement type and aging have no large influence on the relationship between dynamic and static elastic modulus, but the ratio of dynamic and static elastic modulus comes close to 1 as temperature increases. Initial chord elastic modulus, which is calculated at lower strain level of stress-strain curve, has the similar value to dynamic elastic modulus. The relationship between dynamic elastic modulus and compressive strength has the same tendency as the relationship between dynamic and static elastic modulus. The proposed relationship equations between dynamic elastic modulus and static elastic modulus or compressive strength properly estimates the variation of relationships according to cement type, temperature, and aging.

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The Effects of Muscle Strengthening of the Ankle Joints on Postural Sway

  • An, Ho Jung;Kang, Min Soo;Park, Yong Nam
    • 국제물리치료학회지
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    • 제4권2호
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    • pp.557-561
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    • 2013
  • The purpose of this study to identified the effect of muscle strengthening of ankle joints on postural sway. The subjects of this study were 29 healthy adults aged between 20 and 30 years(male 18, female 11). All subjects received ankle muscle strengthening exercise for 3 times, 3 sessions, 30 minutes per week over 4weeks period. The measured item of muscle strength, postural sway. Data collected from all subjects the result were as follows. The ankle strength showed significant increase(p<.05). One leg stand test with eye close increase in static balance(p<.05), left-right sway distance and anterior-posterior sway distance with eye open and close in static balance(p<.05). The result findings show that strength of the ankle joint muscles is a factor which affects postural sway and the ankle joints are important in static balance.

표준전동차 대차틀 피로강도평가(I) (Fatigue strength evaluation of a bogie frame for standard electric multiple unit(I).)

  • 박기준;이호용;이관섭;김원경
    • 한국철도학회논문집
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    • 제3권3호
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    • pp.170-176
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    • 2000
  • Nowadays, the vehicle structure weight of urban transit system has been reduced in order to save energy and materials. However, this light weighted vehicle structure is very important to verify the fatigue strength at the development stage. Bogie system consists of bogie frame, suspensions, wheel-sets, braking system and transmission system. Among these components, the bogie frame is most significant component subjected to the whole vehicle and passenger loads. In this study, the bogie frame for the standard EMU power car is evaluated to the static and fatigue strength. And, the evaluation method is used the JIS E4207 specification throughout the FEM analysis and static load test. The static and fatigue test results for the standard EMU bogie frame of power car has been appeared very safety and stable for the design load conditions.

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고장력강을 이용한 자동차 경량 도어 개발 프로세스 (The Process Development of Automotive Light-Weighting Door using High Strength Steel)

  • 장동환
    • 소성∙가공
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    • 제26권1호
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    • pp.55-62
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    • 2017
  • This paper proposes the process to develop a light-weighting automotive door assembly using high strength steel with low cost penalty. In recent years, the automotive industry is making an effort to reduce the vehicle weight. In this study, inner panels for automotive front door using thinner sheets and quenchable boron steel were designed to reduce the weight of conventional one. In order to evaluate the stiffness properties for the proposed door design, the several static tests were conducted using the finite element method. Based on the simulation results, geometry modifications of the inner panels were taken into account in terms of thickness changes and cost saving. Furthermore, a prototype based on the proposed design has been made, and then static stiffness test carried out. From the results, the proposed door is proved compatible and weight reduction of 11.8% was achieved. It could be a reference process for automotive industry to develop the similar products.

Crack control of precast deck loop joint using high strength concrete

  • Shim, Changsu;Lee, Chi dong;Ji, Sung-woong
    • Advances in concrete construction
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    • 제6권5호
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    • pp.527-543
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    • 2018
  • Crack control of precast members is crucial for durability. However, there is no clear provision to check the crack width of precast joints. This study presents an experimental investigation of loop joint details for use in a precast bridge deck system. High strength concrete of 130 MPa was chosen for durability and closer joint spacing. Static tests were conducted to investigate the cracking and ultimate behavior of test specimens. The experimental results indicate that current design codes provide reasonable estimation of the flexural strength and cracking load of precast elements with loop joint of high strength concrete. However, the crack width control of the loop joints with high strength concrete by the current design practices was not appropriate. Some recommendations to improve crack control of the loop joint were derived.