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An Experimental and Numerical Study of Bird strike on a 2024 Aluminum Double Plate

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Acta Mechanica Solida Sinica 2019年第1期32卷 40-49页

作者： Jun Liu Zongxing Liu Naidan Hou School of Aeronautics Northwestern Polytechnical UniversityNo.127Youyi West RoadXi'an 710072China

This paper presents an experimentai and numerical study of the bird strike on a 2024-T3 aluminum double *** experiments are carried out at a desired impact velocity of 150 m/*** explicit finite element software PAM-CRASH is used to Simulate the birdstrike experiments,and a coupled SPH-FE method is adopted,where the bird is modeled using the SPH method with the Mur naghan EOS and the struc ture is meshed with finite elemen *** mat erial parame ters are identified by an optimization process,and the Simula ted dynamic responses of bird strike are compared with experimentai measurements to verify the numerical *** displacement and strain of the plate as well as the final deformation and damage show good agreemen t bet ween the simulation and the experimental resul *** suggests that the coupled SPH-FE met hod can provide an effec tive tool in designing bird-strike-resista nt aircraft component.

关键词： Bird strike Experiment Simulation SPH PAM-CRASH

Transition to forefoot strike reduces load rates more effectively than altered cadence

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Journal of Sport and Health Science 2020年第3期9卷 248-257页

作者： Erin E.Futrell K.Douglas Gross Darcy Reisman David R.Mullineaux Irene S.Davis Department of Physical Therapy Springfield CollegeSpringfieldMA 01109USA Spaulding National Running Center Harvard Medical SchoolCambridgeMA 02138USA Department of Physical Therapy MGH Institute of Health ProfessionsBostonMA 02129USA Department of Physical Therapy University of DelawareNewarkDE 19713USA School of Sport and Exercise Science University of LincolnBrayford PoolLincolnBrayford PoolLN67TSUK Department of Physical Medicine and Rehabilitation Harvard Medical SchoolBostonMA 02115USA

Background: Excessive vertical impacts at landing are associated with common running injuries. Two primary gait-retraining interventions aimed at reducing impact forces are transition to forefoot strike and increasing cadence. The objective of this study was to compare the shortand long-term effects of 2 gait-retraining interventions aimed at reducing landing ***: A total of 39 healthy recreational runners using a rearfoot strike and a cadence of 170 steps/min were randomized into cadence(CAD) or forefoot strike(FFS) groups. All participants performed 4 weeks of strengthening followed by 8 sessions of gait-retraining using auditory feedback. Vertical average load rates(VALR) and vertical instantaneous load rates(VILR) were calculated from the vertical ground reaction force curve. Both cadence and foot strike angle were measured using 3D motion analysis and an instrumented treadmill at baseline and at 1 week,1 month, and 6 months post ***: ANOVA revealed that the FFS group had significant reductions in VALR(49.7%) and VILR(41.7%), and changes were maintained long term. Foot strike angle in the FFS group changed from 14.2° dorsiflexion at baseline to 3.4° plantarflexion, with changes maintained long term. The CAD group exhibited significant reduction only in VALR(16%) and only at 6 months. Both groups had significant and similar increases in cadence at all follow-ups(CAD, +7.2% to 173 steps/min;and FFS, +6.1% to 172 steps/min).Conclusion: Forefoot strike gait-retraining resulted in significantly greater reductions in VALR and similar increases in cadence compared to cadence gait-retraining in the short and long term. Cadence gait-retraining resulted in small reductions in VALR at only the 6-month follow-up.

关键词： Foot strike Gait-retraining Physical therapy Running Step rate

LARGE-SCALE strike SLIP FAULT: THE MAJOR STRUCTURE OF INTRACONTINENTAL DEFORMATION AFTER COLLISION

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Chinese Science Bulletin 1990年第4期35卷 304-309页

作者：钟大赉 P. TAPPONNIER 吴海威张连生嵇少丞钟嘉猷刘小汉 U. SCHAERER R. LACASSIU P. LELOUP Institute of Geology Academia Sinica Beijing 100011 PRC Institule of Geophysics.C.N.R.S.France

Intracontinental deformation is one of the most interesting problems in tectonics. But so far little attention has been paid to rock deformation, metamorphism and magmatism related with large-scale displacement and rotation of these blocks. In this note, we take the Ailaoshan-Red River fault (ARF)zone in western Yunnan as an example and discuss the kinematics and dynamics of the fault With its neighbouring blocks in the Tertiary.

关键词： intracontinental deformation large-scale strike slip Ailaoshan-Red River fault.

NUMERICAL ANALYSIS OF strike OF PISTON TO CYLINDER UNDER SUPERCHARGE CO NDITIONS

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Journal of Pharmaceutical Analysis 2004年第2期16卷 106-109页

作者：余志壮宋正华董光能谢友柏 Department of Mechanical Engineering Xi'an Jiaotong University Xi'an 710049 China Department of Test Instrument Luoyang Bearing Corp.Luoyang471039China

Objective To investigate th e changes to the strike extent of piston to cylinder after engine supercharge de sign. Methods The lubrication model between the skirt of piston and liner is established by means of piston dynamics, combined with the hydrody namic lubrication equation. Optimized numerical analysis method is employed in s olving the dynamics and lubrication equations. The analyses about piston strike under two combustion gas pressures are performed. Results The p eak values of maximum eccentricity under supercharge condition are much greater than under non-supercharge condition, which means a stronger impulsion of pisto n to cylinder wall and a greater possibility of scuffing. The horizontal velocit ies of piston in supercharge condition are larger, which illuminate the more uns table motion state. Conclusion The analysis gives a new conclus ion. Combustion gas pressure plays an important role in the piston strike motion . Influences of supercharge should be taken into account so that the traditional product test items can be improved.

关键词： piston supercharge strike

INVERSION OF strike-SLIP MOVEMENTS ALONG THE YARLUNG ZANGBO SUTURE ZONE, TIBET

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地学前缘 2000年第S1期7卷 111-112页

作者： Kobayashi Kenta 1, Matsuoka Atsushi 2, Yang Qun 3, Nagahashi Toru 1, Takei Masahiko 1, Zeng Qinggao 4,Wang Yujin 3 (1 Graduate School of Science and Technology, Niigata University, Niigata 950\|2181, Japan 2 Department of Geology, Niigata Uni

Meso\| and microstructural characteristics of cataclastic fault rocks developed in the Xialu chert are described. The Xialu chert represents pelagic and deep marine sediments (Middle Jurassic—Lower Cretaceous), and occupies the southern marginal part of the E—W trending Yarlung Zangbo suture zone. The apparent total thickness of siliceous deposits exceeds 1km. The current study is concentrated along the two measured sections, Xialu\|E and Xialu\|W. The Xialu\|E section is composed mainly of red chert associated with reddish purple siliceous mudstone and greenish gray mudstone. The beds steeply dip north or south. The 45m section studied is divided into three units (chert unit, chert\|siliceous mudstone unit, and melange unit from north to south). They are in fault contact with each other. In the southern half of the chert unit and the northernmost of the chert\|siliceous mudstone unit, a 15m thick cohesive cataclasite zone can be defined. The cataclasites are composed of chert fragments in a fine grained matrix, and deformed with jigsaw puzzle structures. The chert\|siliceous mudstone unit is made up of four slabs of chert\|siliceous mudstone sequence. Mesoscopic duplex zones in thickness from 1 to 3m are recognized at slab boundaries. Flat and ramp structure and associated P foliations, R1 shears, Y surfaces are developed. Shear spacing range from 1 to 10cm. The slip senses are dextral strike\|slip movement along these duplex zones. The cataclasite zone is cut by the duplex zone along the southern boundary.

关键词： Tibet Yarlung Zangbo Suture Zone Xialu chert structural ana lysis fault rocks strike slip inversion

Initial Geometry and strike-Slip Deformation of Skarn Related Iron Deposit: Insights from Paleomagnetic and AMS Investigations(Yamansu Deposit, Eastern Tianshan, China)

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