• 한국압력기기공학회 논문집
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• 제15권2호
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• pp.31-39
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• 2019

Cracked component analysis is needed for structural integrity analysis under seismic loading. Under large amplitude cyclic loading conditions, the change in material properties can be complex, depending on the magnitude of plastic strain. Therefore the cracked component analysis under cyclic loading should consider appropriate cyclic hardening model. This study introduces a procedure for determining an appropriate cyclic hardening model for cracked component analysis. The test material was nuclear-grade TP316 stainless steel. The material cyclic hardening was simulated using the Chaboche combined hardening model. The kinematic hardening model was determined from standard tensile test to cover the high and wide strain range. The isotropic hardening model was determined by simulating C(T) test under cyclic loading using ABAQUS debonding analysis. The suitability of the material hardening model was verified by comparing load-displacement curves of cyclic C(T) tests under different load ratios.

• 한국농공학회논문집
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• 제52권3호
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• pp.73-79
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• 2010

In the present study, the loading frequency dependencies of cyclic shear strength and elastic shear modulus of reconstituted clay were examined by performing undrained cyclic triaxial tests and undrained cyclic triaxial tests to determine deformation properties. The result of undrained cyclic triaxial test of reconstituted and saturated clay shows that a faster frequency leads to higher stress amplitude ratio, but when the frequency becomes fast up to a certain point, the stress amplitude ratio will reach its maximum limit and the frequency dependence becomes insignificant. And also, the result of undrained cyclic triaxial deformation test shows a fact that a faster loading frequency leads to higher equivalent shear modules and smaller hysteresis damping ratio, and confirms the frequency dependence of cohesive soil. Meanwhile, the result of the creep test shows that continuing creep is created in the undrained cyclic triaxial test with slow loading frequency rate, and since loading rate becomes slower at the vicinity of the maximum and the minimum deviator stress due to sine wave loading, the vicinity of the maximum and the minimum deviator stress shall be more influenced by creep.

• 한국지진공학회논문집
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• 제7권5호
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• pp.57-66
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• 2003

본 논문에서는 동반된 논문에서 제안된 수정 병렬 IWAN 모델의 적용성을 금강 모래와 토요라 모래를 대상으로 비틂전단실험을 수행하여 검증하였다. 두가지 사질토에 대해서 대칭 하중과 불규칙 하중을 반복 재하하여 실험을 수행하였다. 제안된 모델의 변수는 다양한 상대밀도와 구속압 조건하에서 대칭 반복하중을 재하하여 결정하였다. 시험 결과, 하중반복회수가 증가함에 따라 발생하는 사질토의 반복경화거동을 수정 병렬 IWAN 모델로 표현 가능하였으며, Pyke(1979)에 의해 제안된 불규칙 하중 형태를 이용한 실험결과를 실험 조건이 유사한 대칭 반복하중 재하실험 결과로 얻어진 모델 변수를 이용하여 예측한 결과 실험 결과와 잘 일치함을 알 수 있었다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1990년도 봄 학술발표회 논문집
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• pp.66-71
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• 1990

The prediction and estimation of R/C structure behavior subjected to earthquake type loading is partly based on the experimental results of the monotonically increased cyclic loading, rather than that of the irregularly increased cyclic loading. However, actual earthquake is typical random vibration. In this respect, comparing and analysing experimental test results of R/C specimens subjected to monotonically increased cyclic loading and irregularly increased cyclic loading, this study proposes the research direction of irregularly increased cyclic loading during earthquake.

• 한국안전학회지
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• 제15권4호
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• pp.35-40
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• 2000

The influence of cyclic loading history on the creep behavior of the 30 vol% hot-pressed $SiC_f/Si_3N_4copmposite was experimentally investigated at $1200^{\circ}C$. The duration of loading/unloading had great effects on the creep behaviors. The short term duration cyclic loading history test results showed significant reduction in the primary and steady-state creep rates. For example, 300sec loading/300sec unloading history resulted in 70% lower steady-state creep rate than that of the continuous loading. However the long term duration cyclic loading history test results showed little change in creep rates compared to those of the continuous one. The reason for the significant change in the short term duration cycles was estimated due to the change in the stress redistribution between the fiber and matrix during the creep recovery in the primary stage.

• 한국농공학회논문집
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• 제46권6호
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• pp.47-58
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• 2004

As concrete structures are getting larger, higher, longer and more specialized, it is more required to develop steel fiber concrete and apply to the real world. In this research, it is aimed to have fatigue strength examined, varying the steel fiber content of 0%, 0.75%, 1.00%, 1.25% by experimental study of fatigue behavior of the steel fiber reinforced concrete continuous beams under cyclic loading. The ultimate load and initial load of flexural cracking were measured by static test. In addition, the load versus strain relation, load versus deflection relation, crack pattern and fracture mode by increasing weight were observed. On the other hand, the crack propagation and the modes of fracture according to cycle number and the relation of cyclic loading to deflection relation and strain relation were investigated by fatigue test. As the result of fatigue test, continuous beam without steel fiber was failed at 60 ~ 70% of The static ultimate strength and it could be concluded that fatigue strength to two million cyclic loading was arround 67.2% by S-N curve. On the other hand, that with steel fiber was failed at 65 ~ 85% of the static ultimate strength and it could be concluded fatigue strength to two million cyclic loading around 71.7%.

• Steel and Composite Structures
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• 제14권6호
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• pp.587-604
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• 2013

There are few technical documents regulated structural performance and engineering criteria in domestic market for Structural insulated panels in Korea. This paper was focused to identify fundamental performance under monotonic loading and cyclic loading for SIPs in shear wall application. Load-displacement responses of total twelve test specimens were recorded based on shear stiffness, strength, ultimate load and displacement. Finally energy dissipation of each specimen was analyzed respectively. Monotonic test results showed that ultimate load was 44.3 kN, allowable shear load was 6.1 kN/m, shear stiffness was 1.2 MN/m, and ductility ratio was 3.6. Cyclic test was conducted by two kinds of specimens: single panel and double panels. Cyclic loading results, which were equivalent to monotonic loading results, showed that ultimate load was 45.4 kN, allowable shear load was 6.3 kN/m. Furthermore the accumulated energy dissipation capability for double panels was as 2.3 times as that for single panel. Based on results of structural performance test, it was recommended that the allowable shear load for panels should be 6.1 kN/m at least.

• 대한치과보철학회지
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• 제43권3호
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• pp.379-392
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• 2005

Statement of problem. One of the common problems of dental implant prosthesis is the loosening of the screw that connects each component, and this problem is more common in single implant-supported prostheses with external connection, and in molars. Purpose. The purposes of this study were: (1) to compare the initial abutment screw detorque values of the six different implant-abutment interface designs, (2) to compare the detorque values of the six different implant-abutment interface designs after cyclic loading, (3) to compare the detorque values of regular and wide diameter implants and (4) to compare the initial detorque values with the detorque values after cyclic loading. Material and methods. Six different implant-abutment connection systems were used. The cement retained abutment and titanium screw of each system were assembled and tightened to 32Ncm with digital torque gauge. After 10 minutes, initial detorque values were measured. The custom titanium crown were cemented temporarily and a cyclic sine curve load(20 to 320N, 14Hz) was applied. The detorque values were measured after cyclic loading of one million times by loading machine. One-way ANOVA test, scheffe’s test and Mann-Whitney U test were used. Results. The results were as follows : 1. The initial detorque values of six different implant-abutment connections were not significantly different(p>0.05). 2. The detorque values after one million dynamic cyclic loading were significantly different (p<0.05). 3. The SS-II regular and wide implant both recorded the higher detorque values than other groups after cyclic loading(p<0.05). 4. Of the wide implants, the initial detorque values of Avana Self Tapping Implant, MIS and Tapered Screw Vent, and the detorque values of MIS implant after cyclic loading were higher than their regular counterparts(p<0.05). 5. After cyclic loading, SS-II regular and wide implants showed higher detorque values than before(p<0.05).

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2009년도 세계 도시지반공학 심포지엄
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• pp.913-922
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• 2009

Fourteen model pile load tests using a calibration chamber and instrumented model pile were preformed to investigate the variation of the behaviors of driven piles in sands with soil and lateral cyclic loading conditions. Results of the model tests showed that the first loading cycle generated more than 70% of the pile head rotation developed for 50 lateral loading cycles. Lateral cyclic loading also made an increase of the ultimate lateral load capacity of piles for $K_0$=0.4 and an decrease for $K_0$ higher than 0.4. Higher portion of the increase or decrease in the ultimate lateral load capacity by lateral cyclic loading was generated for the first loading cycle due to densification of loosening of the soil around the pile by lateral cyclic loading. It was also observed that a two-way cyclic loading caused higher ultimate lateral load capacity of driven piles than a one-way cyclic loading. When the pile was in the ultimate state, the maximum bending moment developed in the pile increased with increasing $K_0$ value of soil and was insensitive to the magnitude and number of lateral cyclic loading.

• Nuclear Engineering and Technology
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• 제48권6호
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• pp.1376-1386
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• 2016

This study investigated the loading rate effect on the fracture resistance under cyclic loading conditions to understand clearly the fracture behavior of piping materials under seismic conditions. J-R fracture toughness tests were conducted under monotonic and cyclic loading conditions at various displacement rates at room temperature and the operating temperature of nuclear power plants (i.e., $316^{\circ}C$). SA508 Gr.1a low-alloy steel and SA312 TP316 stainless steel piping materials were used for the tests. The fracture resistance under a reversible cyclic load was considerably lower than that under monotonic load regardless of test temperature, material, and loading rate. Under both cyclic and monotonic loading conditions, the fracture behavior of SA312 TP316 stainless steel was independent of the loading rate at both room temperature and $316^{\circ}C$. For SA508 Gr.1a lowalloy steel, the loading rate effect on the fracture behavior was appreciable at $316^{\circ}C$ under cyclic and monotonic loading conditions. However, the loading rate effect diminished when the cyclic load ratio of the load (R) was -1. Thus, it was recognized that the fracture behavior of piping materials, including seismic loading characteristics, can be evaluated when tested under a cyclic load of R = -1 at a quasistatic loading rate.