• Title/Summary/Keyword: Slip resistance

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Assessment of Slip Sinkage of an Off-Road Tracked Vehicle from Model Track Experiments (모형궤도시험을 통한 야지궤도차량의 슬립침하 평가)

  • Baek, Sung-Ha;Shin, Gyu-Beom;Chung, Choong-Ki
    • Journal of the Korean Geotechnical Society
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    • v.34 no.6
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    • pp.49-59
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    • 2018
  • When a tracked vehicle travels off-road, shearing action and ground sinkage occur on the soil-track interface and severely affect tractive performance of the tracked vehicle. Especially, the ground sinkage, which is induced by vehicle's weight (hereinafter referred to as static sinkage) and longitudinal forces in the direction of travel producing slip (hereinafter referred to as slip sinkage), develops soil resistance, directly restricting the tractive performance of an off-road tracked vehicle. Thus, to assess the tractive performance of an off-road tracked vehicle, it is imperative to take both of static sinkage and slip sinkage into consideration. In this research, a series of model track experiments was conducted to investigate the slip sinkage which has not been clarified. Experiment results showed that the slip sinkage increased with increasing the slip ratio, but the increasing rate gradually decreased. Also, the slip sinkage was found to increase as relative density of soil decreased and imposed vertical load increased. From the experiment results, the normalized slip sinkage defined as slip sinkage to static sinkage calculated in the identical condition was investigated, and an empirical equation for the slip sinkage was developed in terms of slip ratio, which allows vehicle operators to predict the slip sinkage in a given soil and operating conditions.

Vibration behavior of functionally graded sandwich beam with porous core and nanocomposite layers

  • Si, Hua;Shen, Daoming;Xia, Jinhong;Tahouneh, Vahid
    • Steel and Composite Structures
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    • v.36 no.1
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    • pp.1-16
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    • 2020
  • In steel-concrete composite beams, to improve the cracking resistance of the concrete slab in the hogging moment region, a new type of connector in the interface, named uplift-restricted and slip-permitted screw-type (URSP-S) connector has been proposed. This paper focuses on the behavior of steel-concrete composite beams with URSP-S connectors. A total of three beam specimens including a simply supported beam with URSP-S connectors and two continuous composite beams with different connectors arrangements were designed and tested. More specifically, one continuous composite beam was equipped with URSP-S connectors in negative moment region and traditional shear studs in other regions. For comparison, the other one was designed with only traditional shear studs. The failure modes, crack evolution process, ultimate capacities, strain responses at different locations as well as the interface slip of the three tested specimens were measured and evaluated in-depth. Based on the experimental study, the research findings indicate that the larger slip deformation is allowed while using URSP-S connectors. Meanwhile, the tensile stress reduces and the cracking resistance of the concrete slab improves accordingly. In addition, the overall stiffness and strength of the composite beam become slightly lower than those of the composite beam using traditional shear studs. Moreover, the arrangement suggestion of URSP-S connectors in the composite beam is discussed in this paper for its practical design and application.

Bond-slip behaviour of H-shaped steel embedded in UHPFRC

  • Huang, Zhenyu;Huang, Xinxiong;Li, Weiwen;Chen, Chufa;Li, Yongjie;Lin, Zhiwei;Liao, Wen-I
    • Steel and Composite Structures
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    • v.38 no.5
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    • pp.563-582
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    • 2021
  • The present study experimentally and analytically investigated the push-out behaviour of H-shaped steel section embedded in ultrahigh-performance fibre-reinforced concrete (UHPFRC). The effect of significant parameters such as the concrete types, fibre content, embedded steel length, transverse reinforcement ratio and concrete cover on the bond stress, development of bond stress along the embedded length and failure mechanism has been reported. The test results show that the bond slip behaviour of steel-UHPFRC is different from the bond slip behaviour of steel-normal concrete and steel-high strength concrete. The bond-slip curves of steel-normal concrete and steel-high strength concrete exhibit brittle behaviour, and the bond strength decreases rapidly after reaching the peak load, with a residual bond strength of approximately one-half of the peak bond strength. The bond-slip curves of steel-UHPFRC show an obvious ductility, which exhibits a unique displacement pseudoplastic effect. The residual bond strength can still reach from 80% to 90% of the peak bond strength. Compared to steel-normal concrete, the transverse confinement of stirrups has a limited effect on the bond strength in the steel-UHPFRC substrate, but a higher stirrup ratio can improve cracking resistance. The experimental campaign quantifies the local bond stress development and finds that the strain distribution in steel follows an exponential rule along the steel embedded length. Based on the theory of mean bond and local bond stress, the present study proposes empirical approaches to predict the ultimate and residual bond resistance with satisfactory precision. The research findings serve to explain the interface bond mechanism between UHPFRC and steel, which is significant for the design of steel-UHPFRC composite structures and verify the feasibility of eliminating longitudinal rebars and stirrups by using UHPFRC in composite columns.

Adaptive Control for Speed of Wound Rotor Induction Motor With Slip Energy Recovery

  • Tunyasrirut, Satean;Kanchanatep, Attapol;Ngamwiwit, Jongkol;Furuya, Tadayoshi
    • 제어로봇시스템학회:학술대회논문집
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    • 1998.10a
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    • pp.419-422
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    • 1998
  • This paper presents how to design speed control of wound rotor induction motors with slip energy recovery. The speed is limited at some range of sub-synchronous speed of the rotating magnetic field. The problem with speed control by adjusting resistance value in the rotor circuit reduces the efficiency of power, because of the slip energy is lost when it passes through the rotor resistance. The control system is designed to maintain efficiency of motor, where it recovers loss energy by returning it to the system to improve the efficiency. A new PI control method of adaptive control [1],[13]is applied for the system with cascade type PI controller on the main loop to keep the speed constant and the internal loop to adjust the rotor appropriated current of the load provides the good transient response without overshoot.

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Strain Gradient Crystal Plasticity Finite Element Modeling for the Compression Behaviors of Single Crystals (단결정 압축 변형 거동의 변형구배 결정소성 유한요소해석)

  • Jung, Jae-Ho;Cho, Kyung-Mox;Choi, Yoon Suk
    • Korean Journal of Materials Research
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    • v.27 no.12
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    • pp.679-687
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    • 2017
  • A strain-gradient crystal plasticity finite element method(SGCP-FEM) was utilized to simulate the compressive deformation behaviors of single-slip, (111)[$10{\bar{1}}$], oriented FCC single-crystal micro-pillars with two different slip-plane inclination angles, $36.3^{\circ}$ and $48.7^{\circ}$, and the simulation results were compared with those from conventional crystal plasticity finite element method(CP-FEM) simulations. For the low slip-plane inclination angle, a macroscopic diagonal shear band formed along the primary slip direction in both the CP- and SGCP-FEM simulations. However, this shear deformation was limited in the SGCP-FEM, mainly due to the increased slip resistance caused by local strain gradients, which also resulted in strain hardening in the simulated flow curves. The development of a secondly active slip system was altered in the SGCP-FEM, compared to the CP-FEM, for the low slip-plane inclination angle. The shear deformation controlled by the SGCP-FEM reduced the overall crystal rotation of the micro-pillar and limited the evolution of the primary slip system, even at 10 % compression.

Slip Frequency Andative Tunning for the Compensation of Rotor Resistance Variation of Induction Motor (유도전동기의 회전자저항 변동 보상을 위한 슬립주파수의 적응 조정)

  • 이일형;이윤종
    • Journal of the Korean Society of Safety
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    • v.9 no.4
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    • pp.42-48
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    • 1994
  • A rotor flux error-based approach for correcting the rotor time constant estimation used in the slip frequency calculator of indirect field oriented controller is presented in this paper. The controller was derived from the d-q induction machine model. Slip frequency gain is dependent on the machine parameter errors. And parameter errors result in rotor flux error. Thus, estimated rotor flux is compared to commanded rotor flux. The error between them is used for the estimation of rotor time constant. Simulation results which demonstrate the performance of this approach are presented.

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Thermoplastic Polyurethane (TPU)/Ethylene-Propylene-Diene Monomer Rubber (EPDM) and TPU/Polybutadiene Rubber (BR) Blends for the Application of Footwear Outsole Materials (신발겉창 재료용 열가소성 폴리우레탄 (TPU)/에틸렌-프로필렌-디엔 고무와 TPU/부타디엔 고무 블렌드)

  • Kim, Ji-Hoo;Kim, Gue-Hyun
    • Elastomers and Composites
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    • v.48 no.3
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    • pp.195-200
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    • 2013
  • The main objective of this study is to improve abrasion resistance and wet slip resistance of thermoplastic polyurethane (TPU) by blending with ethylene-propylene-diene monomer rubber (EPDM) or polybutadiene rubber (BR) for the application of the footwear outsole materials. With addition of 10 wt% of EPDM or BR, TPU/EPDM and TPU/BR blends exhibited higher NBS abrasion resistance, tensile properties and wet slip resistance than TPU. However, with further increasing content of EPDM and BR, abrasion resistance and tensile properties of the blends decreased. Improvement in abrasion resistance and tensile properties with 10 wt% of addition of EPDM or BR may be due to better microphase separation of TPU.

Analysis of Dynamic Performance of Model Tranis for Their Drive Train Design (모형기차의 구동부 설계를 위한 동역학적 성능해석)

  • Kim, Suc-Tae;Yoon, Soon-Hyung;Tak, Tae-Oh
    • Journal of the Korean Society for Precision Engineering
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    • v.18 no.3
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    • pp.99-106
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    • 2001
  • Model trains should have very similar motion characteristics to real trains in order to provide realistic feeling to their operators. Main purpose of dynamic analysis of model trains is to predict velocities in straight and circular tracks and estimate stopping distance after power shut off. Equations of motion for a model train are derived that relates velocity, traction, rolling resistance, and pulling force. Also, energy equations for calculating stopping distance after power shut off are derived. Experiments with model trains are preformed to measure velocity, rolling resistance, slip, and stopping distance. The results are compared with the prediction based on the equations of motion, and they showed good agreement. It can be concluded that the prediction is more accurate when the slip between wheel and rail is accounted for. The analysis procedures can be applied to determining various design factors in model trains.

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Vector Control for the Rotor Resistance Compensation of Induction Motor (유도전동기 회전자 저항 보상을 위한 벡터제어)

  • Park, Hyun-Chul;Lee, Su-Woon;Kim, Yeong-Min;Hwang, Jong-Sun
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2001.11b
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    • pp.65-68
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    • 2001
  • In the vector control methods of induction motor, the stator current is divided into the flux and torque component current. By controlling these components respectively, the methods control independently flux and torque as in the DC motor and improve the control effects. To apply the vector control methods, the position of the rotor current is identified. The indirect vector control use the parameters of the machine to identify the position of rotor flux. But due to the temperature rise during machine operation, the variation of rotor resistance degrades the vector control. To solve the problem, the q-axis is aligned to reference frame without phase difference by comparing the real flux component with the reference flux component. Then to compensate the slip, PI controller is used. The proposed method keeps a constant slip by compensating the gain of direct slip frequency when the rotor resistance of induction motor varies. To prove the validations of the proposed algorithm in the paper, computer simulations is executed.

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A Study on Shoes for Culinarian Use in the Kitchen Environment (조리 환경에 적합한 기능성 신발(조리화)에 관한 연구)

  • Oh, Suk-Tae
    • Culinary science and hospitality research
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    • v.15 no.1
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    • pp.296-308
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    • 2009
  • According to Lee In-ja's research into the cooks of Korea, there are more than 1.2 million culinary professionals in Korea. However, it is hard to find studies on their work environment. From this point, this study aims to examine the shoes worn by culinarians in their workplace and facilitate the improved environment to protect culinary professionals against potential dangers such as slips, occupational and industrial injuries and fatigue, on the basis of the shoes they wear. The research was conducted on a representative cross section of safety shoes currently worn by culinary professionals. The four factors to be tested and measured for the study were weight, slip resistance, internal tearing strength and splitting resistance. Findings on inquiry showed that the shoes tested were quite heavy, slippery and readily liable to splitting under low stress - when compared to standardized base figures. In accordance with the results of this experiment, guidelines for four factors of manufacture were suggested. First, chef's shoes should weigh not more than 1% of a wearers weight. Second, they should exhibit more than 0.50 $\mu$ slip resistance. Third, they should withstand at least 50.0 N/mm tearing strength. And finally, they should have upwards of 3.0 kg/cm splitting resistance.

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