• Title, Summary, Keyword: Landing

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Landing Dynamic and Key Parameter Estimations of a Landing Mechanism to Asteroid with Soft Surface

  • Zhao, Zhijun;Zhao, JingDong;Liu, Hong
    • International Journal of Aeronautical and Space Sciences
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    • v.14 no.3
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    • pp.237-246
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    • 2013
  • It is of great significance to utilize a landing mechanism to explore an asteroid. A landing mechanism named ALISE (Asteroid Landing and In Situ Exploring) for asteroid with soft surface is presented. The landing dynamic in the first turning stage, which represents the landing performance of the landing mechanism, is built by a Lagrange equation. Three key parameters can be found influencing the landing performance: the retro-rocket thrust T, damping element damping $c_1$, and cardan element damping $c_2$. In this paper, the retro-rocket thrust T is solved with considering that the landing mechanism has no overturning in extreme landing conditions. The damping element damping c1 is solved by a simplified dynamic model. After solving the parameters T and $c_1$, the cardan element damping $c_2$ is calculated using the landing dynamic model, which is built by Lagrange equation. The validities of these three key parameters are tested by simulation. The results show a stable landing, when landing with the three estimated parameters T, $c_1$, and $c_2$. Therefore, the landing dynamic model and methods to estimate key parameters are reasonable, and are useful for guiding the design of the landing mechanism.

Hard-landing Simulation by a Hierarchical Aircraft Landing Model and an Extended Inertia Relief Technique

  • Lee, Kyu Beom;Jeong, Seon Ho;Cho, Jin Yeon;Kim, Jeong Ho;Park, Chan Yik
    • International Journal of Aeronautical and Space Sciences
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    • v.16 no.3
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    • pp.394-406
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    • 2015
  • In this work, an efficient aircraft landing simulation strategy is proposed to develop an efficient and reliable hard-landing monitoring procedure. Landing stage is the most dangerous moment during operation cycle of aircraft and it may cause structural damage when hard-landing occurs. Therefore, the occurrence of hard-landing should be reported accurately to guarantee the structural integrity of aircraft. In order to accurately determine whether hard-landing occurs or not from given landing conditions, full nonlinear structural dynamic simulation can be performed, but this approach is highly time-consuming. Thus, a more efficient approach for aircraft landing simulation which uses a hierarchical aircraft landing model and an extended inertia relief technique is proposed. The proposed aircraft landing model is composed of a multi-body dynamics model equipped with landing gear and tire models to extract the impact force and inertia force at touch-down and a linear dynamic structural model with an extended inertia relief method to analyze the structural response subject to the prescribed rigid body motion and the forces extracted from the multi-body dynamics model. The numerical examples show the efficiency and practical advantages of the proposed landing model as an essential component of aircraft hard-landing monitoring procedure.

The Effects of Landing Height and Distance on Knee Injury Mechanism (착지의 높이와 거리가 무릎 부상 메카니즘에 미치는 영향)

  • Cho, Joon-Haeng;Kim, Ro-Bin
    • Korean Journal of Sport Biomechanics
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    • v.21 no.2
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    • pp.197-205
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    • 2011
  • Various jumping and landing motions are shown during sports event. But most previous studies have not considered landing height and distance simultaneously. The purpose of this study was to identify the effects of landing height and distance on knee injury mechanism. Fourteen male(age: $28.86{\pm}1.99$ yrs, height: $177.00{\pm}4.69$ cm, weight: $76.50{\pm}6.41$ kg) participated in this study. The subjects attempted drop landing task onto the ground from 30 cm to 45 cm heights and to 20 cm to 40 cm distances. The results were as follows. First, higher drop landing height and longer distance showed greater degree of maximal knee flexion and valgus. Second, higher drop landing height and longer distance showed greater maximal knee extension moment and varus moment. Third, higher drop landing height and longer distance showed larger maximal knee absorption power. Lastly, higher drop landing height showed increased Peak GRF. Landing height was more related to the cause of injury, which was indicated by increased maximal knee extension moment, peak GRF and maximal knee absorption power. Landing distance was also associated with increased knee valgus moment and absorption power during landing. These results suggest that landing height and distance may be the cause of injury.

Finite Element Analysis of Impact Characteristics of Shoes-Leg Coupled Model to landing Mode (착지모드에 따른 신발-족 연계모델의 충격특성 유한요소 해석)

  • Ryu Sung-Heon;Kim Sung-Ho;Cho Jin-Rae
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.29 no.9
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    • pp.1191-1198
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    • 2005
  • This paper is concerned with the numerical investigation of the landing impact characteristics of sport shoes to the landing mode. In most court sport activities, jumping and landing are fundamental motions, and the landing motion is largely composed of forefoot and rearfoot landing modes. Since the landing impact may, but frequently, lead to unexpected injuries of players, the investigation of its characteristics and the sport shoes design for reducing it are of a great importance. To investigate the landing impact characteristics to the landing mode, we construct a shoes-leg coupled model and carry out the numerical simulation by an explicit finite element method.

Research on Landing Impact Characteristic Of Multi-Wheel Bogie Landing gear's Truck

  • Cao, Xin;Jia, Yuhong;Tian, Jiajie
    • International Journal of Aerospace System Engineering
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    • v.2 no.2
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    • pp.83-86
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    • 2015
  • Taking the four-wheel bogie landing gear as an example, the force status of truck-like landing gear during the landing impact was analyzed and the simulation model of four-wheel bogie landing gear was established. Firstly, a landing gear prototyping model was established using CATIA and imported to LMS Virtual.lab. Secondly, dynamic analysis of the landing impact was simulated with the established model. Finally, with the help of LMS Virtual.lab's parametric design ability, the effects of landing approach and truck pitch angle on the landing performance, truck motion and truck beam strength were studied. These conclusions will be useful to the design and analysis of the truck.

Kinetics Analysis during Stance Phase of Fore Foot Contact versus Rear Foot Contact in Running

  • Cho, Woong;Han, Jae Woong;Kim, A Young;Park, Sung Kyu;Kim, Hyung Soo
    • Journal of International Academy of Physical Therapy Research
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    • v.8 no.1
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    • pp.1084-1089
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    • 2017
  • The purpose of this study was to compare and analyze the difference of the ankle joint movements during landing. Seven adult males voluntarily participated in the study and the average foot size of the subjects was 269.8 mm. Image analysis equipment and the ground reaction force plate (landing type) was used to measure th kinetic variables. As a result of this study, it was confirmed that the vertical ground reaction force peak point appeared once in the barefoot with forefoot, while two peak points appeared in the barefoot and functional shoe foot with rear foot landing. About ankle angle, fore foot landing ankle angle, the average with bare foot landing was $-10.302^{\circ}$ and the average with functional shoe foot landing was $-2.919^{\circ}$. Also about rear foot landing, ankle angle was $11.648^{\circ}$ with bare foot landing and $15.994^{\circ}$ with functional shoe landing. The fore foot landing, ankle joint force analysis produced 1423.966N with barefoot and 1493.264N with functional shoes. But, the rear foot landing, ankle joint force analysis produced 1680.154N with barefoot and 1657.286N with functional shoes. This study suggest that the angle of ankle depends on the landing type and bare foot running/functionalized shod running, and ankle joint forces also depends on landing type.

The Effect of Foot Landing Type on Lower-extremity Kinematics, Kinetics, and Energy Absorption during Single-leg Landing

  • Jeong, Jiyoung;Shin, Choongsoo S.
    • Korean Journal of Sport Biomechanics
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    • v.27 no.3
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    • pp.189-195
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    • 2017
  • Objective: The aim of this study was to examine the effect of foot landing type (forefoot vs. rearfoot landing) on kinematics, kinetics, and energy absorption of hip, knee, and ankle joints. Method: Twenty-five healthy men performed single-leg landings with two different foot landing types: forefoot and rearfoot landing. A motion-capture system equipped with eight infrared cameras and a synchronized force plate embedded in the floor was used. Three-dimensional kinematic and kinetic parameters were compared using paired two-tailed Student's t-tests at a significance level of .05. Results: On initial contact, a greater knee flexion angle was shown during rearfoot landing (p < .001), but the lower knee flexion angle was found at peak vertical ground reaction force (GRF) (p < .001). On initial contact, ankles showed plantarflexion, inversion, and external rotation during forefoot landing, while dorsiflexion, eversion, and internal rotation were shown during rearfoot landing (p < .001, all). At peak vertical GRF, the knee extension moment and ankle plantarflexion moment were lower in rearfoot landing than in forefoot landing (p = .003 and p < .001, respectively). From initial contact to peak vertical GRF, the negative work of the hip, knee, and ankle joint was significantly reduced during rearfoot landing (p < .001, all). The contribution to the total work of the ankle joint was the greatest during forefoot landing, whereas the contribution to the total work of the hip joint was the greatest during rearfoot landing. Conclusion: These results suggest that the energy absorption strategy was changed during rearfoot landing compared with forefoot landing according to lower-extremity joint kinematics and kinetics.

A Case Study in the Mars Landing Site Selection for Science Objects

  • Seo, Haingja;Kim, Eojin;Kim, Joo Hyeon;Lee, Joo Hee;Choi, Gi-Hyuk;Sim, Eun-Sup
    • Journal of Astronomy and Space Sciences
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    • v.29 no.4
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    • pp.375-380
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    • 2012
  • It is a crucial matter to select a landing site for landers or rovers in planning the Mars exploration. The landing site must have not only a scientific value as a landing site, but also geographical features to lead a safe landing for Mars probes. In this regard, this study analyzed landing site of Mars probes and rovers in previous studies and discussed the adequacy of the landing site to scientific missions. Moreover, this study also examined domestic studies on the Mars. The frameworks of these studies will guide the selection of exploration sites and a landing site when sending Mars probe to the Mars through our own efforts. Additionally, this paper will be used as the preliminary data for selection of exploration site and a landing site.

Dynamic Load Analysis of Aircraft Landing Gear (항공기 착륙장치 동하중 해석)

  • Shin, Jeong-Woo;Kim, Tae-Uk;Hwang, In-Hee
    • Journal of the Korean Society for Aviation and Aeronautics
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    • v.16 no.1
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    • pp.1-6
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    • 2008
  • Role of landing gear is to absorb energy which is generated by aircraft ground maneuvering and landing. Generally, in order to absorb the impact energy, oleo-pneumatic type shock absorber is used in aircraft landing gear. Oleo-pneumatic type shock absorber has a good energy absorption efficiency and is light in weight because structure of oleo-pneumatic type shock strut is relatively simple. In this study, dynamic load analysis for swinging arm type landing gear was performed to predict landing loads. Modeling of landing gear was conducted with MSC.ADAMS, and dynamic landing loads were analyzed based on ADS-29. Optimum landing loads were generated through adjustment of damping orifice and the analysis results were presented with various aircraft attitude.

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Effects of Landing Tasks on the Anterior Cruciate Ligament Injury Risk Factors in Female Basketball Players (여자 농구 선수들의 착지 유형이 전방십자인대 손상위험 요인에 미치는 영향)

  • Lee, Gye-San;Lim, Bee-Oh
    • Korean Journal of Sport Biomechanics
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    • v.24 no.4
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    • pp.385-390
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    • 2014
  • The purpose of this study was to investigate the effects of landing tasks on the anterior cruciate ligament (ACL) injury risk factors in female basketball players. Fifteen female basketball players performed a drop landing and a drop landing with a vertical jump on the 40 cm height box. Three-dimensional motion analysis system and ground reaction force system was used for calculate the ACL injury risk factors. Paired samples t-test with Bonfferoni correction were performed. The drop landing with a vertical jump had the higher knee flexion angle, peak knee varus moment, trunk flexion angle than a drop landing. However, the drop landing had the higher trunk rotation angle than a drop landing with a vertical jump. These results indicate that seemingly minor variations between drop landing and drop landing with a vertical jump may influence the ACL injury risk factors. Caution should be used when comparing studies using different landing tasks.