브레이크용 모터의 축 방향 하중에 따른 기계적 손실을 고려한 특성 분석

원태준(Tae-Juu Weon),정재식(Jae-Sik Jung),박현진(Hyun-Jin Park),홍정표(Jung-Pyo Hong) 한국자동차공학회 2018 한국자동차공학회 부문종합 학술대회 Vol.2018 No.6

This paper presents characteristic analysis of surface permanent magnet synchronous motor(SPMSM) considering mechanical loss according to rotor axial load by oil pressure in brake system. If rotor is forced in axial direction, mechanical loss increases. Mechanical loss is one of major components which affect on efficiency. To consider mechanical loss, no load loss is measured at axial load condition. Mechanical loss is calculated by subtracting core loss from no load loss. Mechanical loss is increased as rotor axis is forced and rotates more quickly. Motor characteristic comparison between model with axial load and model without axial load is done. In case of model with axial load, motor performance decreases compared to model without axial load. In conclusion, Mechanical loss by axial load reduces torque and efficiency in high speed region.

양방향 재하시험을 이용한 말뚝의 하중-변위곡선 추정방법

권오성,권오균,김명모,최용규 한국지반공학회 2006 한국지반공학회논문집 Vol.22 No.4

For the last decade, the bi-directional testing method has been advantageous over the conventional pile load testing method in many aspects. However, because the bi-directional test uses a loading mechanism entirely different from that of the conventional pile load testing method, many investigators and practicing engineers have been concerned that the bi-directional test would give inaccurate results, especially about the pile head settlement behavior. Therefore, a bi-directional load test and the conventional top-down load test were executed on 1.5 m diameter cast-in-situ concrete piles at the same time and site. Strain gauges were placed on the piles. The two tests gave similar load transfer curves at various depth of piles. However, the top-down equivalent curve constructed from the bi-directional load test results predicted the pile head settlement under the pile design load to be about one half of that predicted by the conventional top-down load test. To improve the prediction accuracy of the top-down equivalent curve, a simple method that accounts for the pile compression is proposed. It was also shown that the strain gauge measurement data from the bi-directional load test could reproduce almost the same top-down curve.

반복하중 하에서 건조 및 포화된 화강암과 사암의 물리적 및 역학적 변화 특성

나태유 ( Tae Yoo Na ),고진석 ( Chin Surk Ko ),강성승 ( Seong Seung Kang ) 조선대학교 공학기술연구원 2014 공학기술논문지 Vol.7 No.1

The purpose of this study is to examine physical and mechanical variations such as absorption, porosity, P-wave velocity(Vp), uniaxial compressive strength(UCS), Poisson s ratio( ) and Young s modulus(E) of dried and saturated granite and sandstone under cyclic loading. For this purpose, firstly 100% load(breaking strength) is measured each of granite and sandstone. Secondly, Load test of 50% and 80% load were carried out. Then, their physical and mechanical differences were compared and analyzed. Finally, physical and mechanical variations of granite and sandstone were quantitatively analysed. By the results, UCS of sandstone was bigger than that of granite under dried and saturated conditions, while the variation of the measured porosity and absorption on granite and sandstone was very small. The measured Vp of dried granite and sandstone were increased after loading, while Vp of granite under cyclic loading was decreased. Vp of saturated granite and sandstone were faster than each of dried specimens, and Vp after loading was decreased. Poisson s ratio( ) and Young s modulus(E ) of dried and saturated granite and sandstone showed inverse proportion. As a result, it suggests that physical and mechanical variations of dried and saturated granite and sandstone are dependent on load, and also highly affected by existence of micro-cracks.

신경전달물질 및 물리적 자극에 대한 뼈 세포의 반응

곽지현,김병관,김경환,김지현,Kwag, J.H.,Kim, B.G.,Kim, K.H.,Kim, C.H. 대한의용생체공학회 2009 의공학회지 Vol.30 No.1

Bone remodeling is a continuous process of skeletal renewal during which bone formation is tightly coupled to bone resorption. Mechanical loading is an important regulator of bone formation and resorption. In recent studies, neurotransmitters such as vasoactive intestinal peptide (VIP) were found to be present inside bone tissue and have been suggested to potentially regulate bone remodeling. In this study, our objective was to use a pre-established in vitro oscillatory fluid flow-induced shear stress mechanical loading system to quantify the effect of VIP on bone resorptive activity and investigate its combined effect with mechanical loading. VIP decreased osteoclastogenesis significantly decreased RANKL/OPG mRNA ration by approximately 90%. Combined VIP and mechanical loading further decreased RANKL/OPG ratio to approximately 95%. These results suggest that VIP present in bone tissue may synergistically act with mechanical loading to regulate bone remodeling via suppression of bone resorptive activities.

Experimental Study of Mechanical Behavior of Passive Loaded Piles Adjacent to Piled Foundation

Yu Xie,Shao-he Zhang,De-quan Zhou 대한토목학회 2018 KSCE JOURNAL OF CIVIL ENGINEERING Vol.22 No.10

For combined piled foundation, passive loaded piles will be subjected to horizontal force when piled foundation is loaded, and horizontal force may cause the piles horizontal displacement, instability or even failure. With inclined bedrock nearby, the mechanical behavior of passive loaded piles will be more complex. In order to study the mechanical behavior of passive loaded piles under such condition, laboratory model test was carried out, during repeatedly loading/unloading cycles. Axial force, side friction, bending moment, and lateral soil pressure were analyzed. The study is based on model test, and more related studies are needed before being applied to practical conditions. The results show as follows: Axial force distribution of the piles changes with the increase of load and becomes stable under high load. This phenomenon is related to the expansion of potential slip surface in piled foundation. The passive loaded pile that is close to load boundary has only one neutral point which is located in the lower part of the pile, and its side friction has a relatively stable direction. On the contrary, the direction of side friction of the pile that is far from load boundary changes frequently. Bending moment curves of passive loaded piles vary with the change of the distance between the piles and load boundary, and they intersect at the lower part of the pile. Bending moment is basically negative above the intersection and gradually turns into positive below it. The maximum lateral soil pressure of passive loaded pile is triple that of the adjacent soil, indicating that passive loaded pile can effectively limit the horizontal deformation of piled foundation. But when the pile is too far from load boundary, it will lose the ability to limit the horizontal deformation of piled foundation.

풍력발전시스템의 기계적 하중 데이터 분석 프로그램 개발과 시뮬레이션 데이터 적용 사례

방제성(Je-Sung Bang),한정우(Jeong-Woo Han),길계환(Kyehwan Gil) 대한기계학회 2013 大韓機械學會論文集B Vol.37 No.8

형식인증시험을 통해 획득된 풍력발전기의 기계적 하중 데이터를 분석하기 위한 관련 프로그램개발과 절차가 수행되었다. IEC 61400-13 규격을 기반으로 하는 측정 데이터에 대한 검증, 하중유형에 따른 분류, 시계열 및 통계 데이터 분석, 파워 스펙트럼 밀도함수 및 피로하중 스펙트럼 계산, 등가하중 계산 등의 절차가 본 프로그램을 통해 수행되었다. 수집된 데이터들이 피로하중을 산정하기에 충분한가를 판단하기 위해 정상전력생산의 경우에 대한 수집행렬을 구성하였다. 50 개의 하중 범위 분할 개수를 사용하는 우수집계법을 통해 피로하중 스펙트럼이 얻어지며, 사용된 재료에 따라 다르게 S-N 선도의 기울기를 적용하여 최종적으로 등가하중을 산출하였다. 모노파일 하부구조를 가지는 NREL 5MW 풍력발전기의 공탄성 시뮬레이션 데이터에 이용하여 위의 전반적인 절차를 수행하였다. The procedures and relevant programs developed for analyzing mechanical load data of wind turbine generator systems, which are obtained through type certification tests, are verified. The following issues according to IEC 61400-13 are covered in the developed programs: data validation, time series analysis, summary load statistics, generation of fatigue load spectra, and estimation of equivalent loads. A capture matrix for normal power production is generated to determine whether the collected data sets are sufficient to carry out fatigue analysis. Fatigue load spectra are obtained through the rainflow counting method using 50 load ranges; finally, equivalent loads are calculated using different S-N curve slopes, m, according to the relevant materials. Case studies are performed using aero-elastic simulation data of the NREL 5 MW baseline wind turbine with a monopile foundation.

Optimal design of micro-nano displacement driving mechanism for obtaining mechanical properties of micro structure

Biao Wang,Yan Huang,Yonghong Wang,Peizheng Yan,Qiaosheng Pan 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.5

The mechanical structures of micro-electro-mechanical systems (MEMS) are composed of different types of microstructures, and their mechanical properties are very important for the realisation and reliability of the system performance. One of the key problems in measuring the mechanical properties is the design and implementation of micro-nano displacement driving mechanisms. This paper describes a mechanism that adopts a two-level loading strategy, fast approach, and precise bending displacement loading structures, and has a theoretical analysis and optimal design based on optimal targets of resistance and displacement. The results show that the relative error is 6.98 % for the fast-approaching structure experiment and its optimal simulation and 4.26 % for the precise bending displacement loading structure (PBLS) experiment and its optimal simulation. The optimised micro-nano displacement loading mechanism can achieve optimal output performance under existing constraints.

Uniaxial Eccentric Load Behavior of L-CFSST Composite Column

Zhen Wang,Zhe Liu,Xingbo Wang,Xuejun Zhou,Zhoutai Wang,Guodong Xian 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.5

This study presents the mechanical behavior of L-shaped concrete-filled square steel tube (L-CFSST) composite columns under uniaxial eccentric compression. Nine specimens were tested and the effects of eccentricity, steel tube thickness, steel yield strength, and slenderness ratio were investigated regarding failure modes, ultimate load, load-lateral displacement curves, and load-strain curves. Test results showed that, under uniaxial eccentric load, these columns showed favorable mechanical properties and steel tubes showed strong cooperative working performance. There were two types of failure modes for these columns: local buckling of the steel tube or overall bending of the specimen. ABAQUS was used to simulate the loading process and the accuracy of the numerical simulation results was verified by comparing failure characteristics, load-displacement curves, and ultimate bearing capacity with the test results. The N/Nu-M/Mu curves of the columns under uniaxial eccentric load with different parameters were simulated by the finite element method. A simplified formula for predicting the N/Nu-M/Mu relationship was established based on the finite element analysis results, which might be a workable approach for designing L-CFSST composite columns in engineering practice.

Study on mechanical behaviors of column foot joint in traditional timber structure

Juan Wang,Jun-Xiao He,Qingshan Yang,Na Yang 국제구조공학회 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.66 No.1

Column is usually floating on the stone base directly with or without positioning tenon in traditional Chinese timber structure. Vertical load originated by the heavy upper structure would induce large friction force and compression force between interfaces of column foot and stone base. This study focused on the mechanical behaviors of column foot joint with consideration of the influence of vertical load. Mechanism of column rocking and stress state of column foot has been explored by theoretical analysis. A nonlinear finite element model of column foot joint has been built and verified using the full-scale test. The verified model is then used to investigate the mechanical behaviors of the joint subjected to cyclic loading with different static vertical loads. Column rocking mechanism and stress distributions of column foot were studied in detail, showing good agreement with the theoretical analysis. Mechanical behaviors of column foot joint and the effects of the vertical load on the seismic behavior of column foot were studied. Result showed that compression stress, restoring moment and stiffness increased with the increase of vertical load. An appropriate vertical load originated by the heavy upper structure would produce certain restoring moment and reset the rocking columns, ensuring the stability of the whole frame.

Study on mechanical behaviors of column foot joint in traditional timber structure

Wang, Juan,He, Jun-Xiao,Yang, Qing-Shan,Yang, Na Techno-Press 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.66 No.1

Column is usually floating on the stone base directly with or without positioning tenon in traditional Chinese timber structure. Vertical load originated by the heavy upper structure would induce large friction force and compression force between interfaces of column foot and stone base. This study focused on the mechanical behaviors of column foot joint with consideration of the influence of vertical load. Mechanism of column rocking and stress state of column foot has been explored by theoretical analysis. A nonlinear finite element model of column foot joint has been built and verified using the full-scale test. The verified model is then used to investigate the mechanical behaviors of the joint subjected to cyclic loading with different static vertical loads. Column rocking mechanism and stress distributions of column foot were studied in detail, showing good agreement with the theoretical analysis. Mechanical behaviors of column foot joint and the effects of the vertical load on the seismic behavior of column foot were studied. Result showed that compression stress, restoring moment and stiffness increased with the increase of vertical load. An appropriate vertical load originated by the heavy upper structure would produce certain restoring moment and reset the rocking columns, ensuring the stability of the whole frame.