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DYNAMIC MECHANICAL BEHAVIOR OF 6061 AL ALLOY AT ELEVATED TEMPERATURES AND DIFFERENT STRAIN RATES

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Acta Mechanica Solida Sinica 2013年第2期26卷 111-120页

作者： Xueling Fan Tao Suo Qin Sun Tiejun Wang State Key Laboratory for Strength and Vibration of Mechanical Structures School of Aerospace EngineeringXi'an Jiaotong University School of Aeronautics Northwestern Polytechnical University

The compressive stress-strain relationships of 6061A1 alloy over wide temperatures and strain rates are investigated. The dynamic impact experiments are performed using an im- proved high temperature split Hopkinson pressure bar apparatus. The experimental results are compared with those obtained by the modified Johnson-Cook constitutive model. It is found that the dynamic mechanical behavior depends sensitively on temperature under relatively low strain rates or on strain rate at relatively high temperatures. The good agreement indicates that it is valid to adopt the parameter identification method and the constitutive model to describe and predict the mechanical response of materials.

关键词： dynamics plastic high temperature alloy impact testing

Effects of surface topography and specimen thickness on high-speed raindrop impact damage of CFRP laminates

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Chinese Journal of Aeronautics 2023年第6期36卷 186-200页

作者： Naidan HOU Renxi ZHAO Xuan WANG Zhongbin TANG Hao CUI Yulong LI School of Aeronautics Northwestern Polytechnical UniversityXi'an 710072China Joint International Research Laboratory of impact Dynamics and Engineering Application Xi'an 710072China Shaanxi Key Laboratory of impact Dynamics and Engineering Application Xi'an 710072China School of Civil Aviation Northwestern Polytechnical UniversitySuzhou 215400China NPU Yangzi River Delta Research Institute Suzhou 215400China

Raindrop impact erosion has been observed since early days of aviation,and can be catastrophic for exposed materials during supersonic flight.A single impact waterjet apparatus is established for mimicking drop impacts at the velocities between 350 m/s and 620 m/*** Fiber Reinforced Polymer(CFRP)laminates with three different surface morphologies and specimen thicknesses are tested here.A central region with no visible damage has been noticed,surrounded by a"failure ring"with common damage patterns including resin removal,matrix cracking,fiber breakage and mass fiber *** features are presented in the"failure ring"whose whole scope extends larger along the longitudinal direction than the transverse direction of the top *** mechanism of the resin removal is related to fiber-matrix debonding,and its onset and propagation can be facilitated by initial surface asperities with the shear action of the lateral *** cases of multiple impact,good surface quality can slow down the evolution of resin removal and fiber exposure on the CFRP surface,reducing the erosion speed and delaying the occurrence of structural damages in the subsequent *** wave dominates the occurrence of matrix cracking on the CFRP surface,and subsequently,results in material loss and peeling of the top-layer because of lateral *** the increase of the specimen thickness,both the interlaminar and intralaminar failures decrease as the impact damage mechanism changes from plate bending stress to the reflection of stress waves.

关键词： Carbon fiber reinforced plastics Failure analysis impact testing Lateral jetting Surface roughness Waterjet

Dynamic fracture toughness of TA15ELI alloy studied by instrumented impact test

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Rare Metals 2010年第6期29卷 608-612页

作者： LIU Rui,HUI Songxiao,YE Wenjun,XIONG Baiqing,YU Yang,and FU Yanyan State Key Laboratory for Fabrication & Processing of Nonferrous Metals,General Research Institute for Nonferrous Metals,Beijing 100088,China State Key Laboratory for Fabrication & Processing of Nonferrous Metals General Research Institute for Nonferrous Metals Beijing China

The dynamic fracture toughness of TA15ELI alloy with two types of microstructures was studied by instrumented impact *** specimens with both the 0.2 mm U-notch and the a/W = 0.2 pre-crack were adopted to compare notch sensitivity in the two *** result shows that the specimen with Widmanst？tten microstructure exhibits a better dynamic fracture toughness and lower notch sensitivity than that with lath-like *** surfaces in the case of the two microstructures are analyzed to have a ductile and brittle mixed feature under dynamic *** fracture surface of lath-like microstructure is composed of dimples and tear ridges,while that of Widmanst？tten microstructure is covered with rough block-like facets and dimples and tear *** α phase boundaries and α/β interfaces act as locations for void nucleation and crack arrest and *** decrease in width of α phase lamellae leads to the increase in the amount of boundaries and interfaces,which causes the increase in the consumption of impact energy and results in the improvement in dynamic fracture toughness.

关键词： titanium alloys fracture toughness impact testing microstructure

impact-SLIDING WEAR OF MATERIALS

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Transactions of Nanjing University of Aeronautics and Astronautics 2009年第4期26卷 251-258页

作者：魏勇强王黎钦哈尔滨工业大学机电工程学院

A simple impact-sliding wear test rig is designed for studying the wear behavior between solid materials on a repetitive normal impact accompanied with the tangential sliding. The test rig consists of a cantilever beam forced by the dynamoelectric vibration exciter and a rotational shaft driven by a spindle. It has a widely adjustable range of testing parameters, including the impact frequency, the impact load and the sliding velocity. The avail- able maximum impact frequency, impact load and sliding velocity are 100 Hz, 200 N and 4.52 m/s, respectively. To evaluate the capability of the test rig, tests are carried out and the impact load is measured. Results show that the test rig has the good repeatability under the same test conditions and the repeatable error is less than 7%. Furthermore, non-destructive examination results by the mass loss method, two-dimensional profilometry and the scanning electron microscopy （SEM） show that the test rig can meet the demands for the impact-sliding wear.

关键词： wear of materials impact testing aluminum alloys titanium alloys

ELASTICITY EFFECTS ON THE WATER impact OF AN ELASTIC FLAT-BOTTOM BOX

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Journal of Hydrodynamics 2002年第2期14卷 64-70页

作者： Li, Wan-Ping Liu, Gui-Rong Chan, Eng-Song Huazhong Univ. of Sci. and Technol. Wuhan 430074 China Natl. Univ. of Singapore Singapore 119260 Singapore

To elucidate the effects of elasticity the hydrodynamic impact of a 2-D flat-bottom shell box onto a water surface was investigated in detail using the finite element code Dytran. An ALE coupling algorithm was employed to handle the interactions between the box and the fluids. In this study, both air and water were treated as compressible fluids and their properties were modeled through the equation of states. Calculated results show that the air cushion plays a very important role buffering the impinging. Under the deformed concave bottom an air cushion layer will be easier to form up. For high impact speed, the pressure for the elastic box is much lower than that for the rigid box. Excited by the impact, the impinging box oscillates with about its natural frequency.

关键词： Air cushioning Compressible flow Elasticity Finite element method impact testing Water

State of the art of impact testers for spot welds

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Engineering Sciences 2014年第5期12卷 59-66页

作者： Hua Fu' an Ma Mingtu Li Jianping Wang Guodong The State Key Laboratory of Rolling and Automation Northeastern University Shenyang 110819 China China Automotive Engineering Research Institute Co. Ltd. Chongqing 401122 China Chongqing New Material Engineering Center Chongqing 400039 China

impact testing is a primary method to evaluate the impact property of resistance spot welding,which is an important quality index in automotive *** testing impact properties of spot welds,many customized testers have been *** paper summarized some of the impact testers reported in open literatures and the emphasis was placed on the equipment structures,functions,technical parameters,advantages and disadvantage,*** key issues about the development of the testers such as kinematic energy input mode,fixture design,combined load testing,sensor and data acquisition were ***,the problems and prospects in the research and development of impact testers for spot welds were pointed out.

关键词： resistance spot welding impact testing impact tester impact strength