Study on Damage Characteristics of Concrete under Impact Load and the Constitutive Model after Damage

2011 ◽  
Vol 48-49 ◽  
pp. 1137-1142
Author(s):  
Bin Jia ◽  
Zheng Liang Li ◽  
Hua Chuan Yao ◽  
Xiao Wei Zhu
Keyword(s):  
Impact Load ◽  
Impact Damage ◽  
Strain Process ◽  
Testing Data ◽  
Freezing Test ◽  
Strain Threshold ◽  
The Impact ◽  
Dynamic Damage ◽  
Theoretical Results ◽  
Good Agreement

The damage ‘freezing’ test of concrete was carried out with the static load and SHPB testing technique, so the relatively loss ultimate bearing capacity could express the damage in macro-level. The result showed that the dynamic damage of the concrete increased with the increasing strain or strain rate and the dynamic damage had a certain strain threshold. Based on the damage evolutive law of concrete whose probability density was distributed Weibul1 distribution, the impact damage factor equation was put forward. Besides, the unified equation which described the whole stress-strain process of the concrete after impact damage were established. Compared with the testing data, it showed that the experiment and theoretical results were in good agreement.

Air Impact Drive for Positioning by Pulse and Continuous Air Pressure

1999 ◽  
Vol 11 (4) ◽  
pp. 263-268 ◽  
Author(s):  
Mohammad Hossein Kouklan ◽  
◽  
Yousef Hojjat ◽  
Toshiro Higuchi ◽  
Keyword(s):  
Pulse Pressure ◽  
Air Pressure ◽  
Impulsive Force ◽  
Precise Positioning ◽  
Good Linearity ◽  
Free Body ◽  
The Impact ◽  
Theoretical Results ◽  
Good Agreement

In recent years, the application of impacts to precise positioning has been increased. Previously, the impulsive force or impact was generated by electromagnetic impulsive force or by the sudden deformation of a piezoelement. In this paper, a new actuator named as Air Impact Drive (AID) is introduced, in which the impact is generated by impulsive air pulse pressure. Free body diagrams and equations of this new actuator were drawn and determined. Experimental and theoretical results are in good agreement. The new actuator could displace a 0.2kg object at 0.1 of millimeter per pulse by pulse air pressure. By implementing suitable setup of parameters, the AID could move the object by continuous, constant air pressure with good linearity. This property is unique among other impact drives for positioning. By 0.3Mpa of source air pressure, the new actuator could move the mentioned object at the speed of approximately 13.4mm/s.

Impact Damage Monitoring in Composite Plates

2004 ◽  
Author(s):  
Frank J. Shih ◽  
Sauvik Banerjee ◽  
Ajit K. Mal
Keyword(s):  
Impact Load ◽  
Impact Damage ◽  
Composite Plates ◽  
Impact Testing ◽  
Far Field ◽  
Internal Damage ◽  
Distributed Sensors ◽  
Surface Motion ◽  
Impact Monitoring ◽  
The Impact

This paper is concerned with the real-time detection of internal damage in composite structural components during impact using the far-field surface motion generated by these events. Impact tests are carried out on graphite epoxy composite plates using an instrumented impact testing system. Contact force and surface motion are measured at several locations on the plate surface. The far-field surface motions, both flexural and extensional waves in the composite plate, are modeled using both approximate and exact solution methods. Postimpact test were performed to determine the extent of internal damage caused by the impact load. Further research on the detection method can lead to the development of a viable impact monitoring system for composite aerospace structures using distributed sensors.

Impact Response and Simulation of Damaged Ulna With Internal Fixation

2012 ◽  
Vol 28 (3) ◽  
pp. 324-334
Author(s):  
Cameron Coates ◽  
Priya Goeser ◽  
Camille Coates-Clark ◽  
Mark Jenkins
Keyword(s):  
Impact Test ◽  
Impact Load ◽  
Impact Damage ◽  
Dynamic Compression ◽  
Dynamic Strain ◽  
Fe Model ◽  
Transverse Impact ◽  
Case Scenario ◽  
Worst Case ◽  
The Impact

The objectives of this work were to explore a methodology that combines static and dynamic finite element (FE) analysis, linear elastic fracture mechanics (LEFM) and experimental methods to investigate a worst-case scenario in which a previously damaged bone plate system is subjected to an impact load. Cadaver ulnas with and without midshaft dynamic compression plates are subjected to a static three-point bend test and loaded such that subcritical crack growth occurs as predicted by a hybrid method that couples LEFM and static FE. The plated and unplated bones are then unloaded and subsequently subjected to a midshaft transverse impact test. A dynamic strain-based FE model is also developed to model the midshaft transverse impact test. The average value of the impact energy required for failure was observed to be 10.53% greater for the plated set. There appears to be a trade-off between impact damage and impact resistance when ulnas are supported by fixation devices. Predictions from the dynamic FE model are shown to corroborate inferences from the experimental approach.

Study on damage behavior of carbide tool for milling difficult-to-machine material

2018 ◽  
Vol 233 (2) ◽  
pp. 735-747
Author(s):  
Yao-Nan Cheng ◽  
Wan-Ying Nie ◽  
Rui Guan ◽  
Wei-Kun Jia ◽  
Fu-gang Yan
Keyword(s):  
Failure Modes ◽  
Impact Load ◽  
Impact Damage ◽  
High Plasticity ◽  
Carbide Tool ◽  
Machine Material ◽  
Tool Failure ◽  
Damage Behavior ◽  
Tool Damage ◽  
The Impact

Water chamber head is an important component of nuclear power unit, and the main material is 508 III steel of difficult-to-machine material, which has the characteristics of high hardness, high strength, high plasticity and high profile shrinkage, etc. During the milling process, the tool is subjected to the cyclic impact load, which make cutting force and cutting heat change violent and occurrence of tool damage failure accelerate. In this paper, the damage behavior of carbide tool for milling difficult-to-machine material is studied first, and then field experiment was carried out on 508 III steel material, tool failure modes were analyzed, which include impact damage and fatigue fracture, and the failure theory and the crack propagation of carbide material were investigated in the process of tool damage. Then, the impact damage model of carbide tool is established based on the classical strength theory, and the critical condition of impact damage is determined according to simulation analysis. Finally, the theoretical model of carbide tool fatigue life is established and the tool fatigue limit is analyzed. Theoretical basis and technical support are provided for the tool failure mechanisms analysis, life prediction, parameter optimization, tool design and development aspects during the study.

scholarly journals Dynamic Model and Mechanical Properties of the Two Parallel-Connected CRLD Bolts Verified with the Impact Tensile Test

2018 ◽  
Vol 2018 ◽  
pp. 1-17
Author(s):  
Liangjun Hao ◽  
Weili Gong ◽  
Manchao He ◽  
Yanqi Song ◽  
Jiong Wang
Keyword(s):  
Dynamic Model ◽  
Impact Load ◽  
Tensile Tests ◽  
Dynamic Responses ◽  
Structural Deformation ◽  
Essential Difference ◽  
Support Design ◽  
The Impact ◽  
Theoretical Analyses ◽  
Theoretical Results

Dynamic model was theoretically established for the two parallel-connected constant-resistance-large-deformation (CRLD) bolts, and the theoretical results were experimentally verified with impact tensile tests on the CRLD bolts samples. The dynamic responses of the double CRLD bolts were investigated under the impact loads with different intensities. The theoretical analyses showed that (1) under relatively small loading the CRLD bolts deform elastically and the deformation finally returns to zero and (2) under the high impact load, including the stable impact load and unstable impact load, the CRLD bolts export structural deformation after the initial elastic deformation. The deformation of the bolts eventually stabilizes at a certain amount of the elongation caused by the relative sliding of the sleeves and rebars. The essential difference between the stable impact load and unstable impact load is that, under the stable impact load, no structural deformation will occur after the impact load ends; under the unstable impact load, the structural deformation will still occur after the impact load ends. The obtained results are of theoretical implications for rock support design with CRLD bolts under the dynamical loading condition.

scholarly journals Experiment and Analysis on the Free Dynamics of a Shallow Arch After an Impact Load at the End

2005 ◽  
Vol 72 (1) ◽  
pp. 54-61 ◽  
Author(s):  
Jen-San Chen ◽  
Chun-Yi Liao
Keyword(s):  
Transient Response ◽  
Impact Load ◽  
Minimum Energy ◽  
The Other ◽  
Initial Speed ◽  
Attached Mass ◽  
Shallow Arch ◽  
Theoretical Predictions ◽  
The Impact ◽  
Good Agreement

In this paper we consider a sinusoidal arch with one end pinned in space while the other end attached to a mass and supported by a spring. The supporting wall of the spring is moved a distance quasi-statically to initiate preload in the arch and the spring. The assembly is then set in motion by an impact at the attached mass. The condition under which the arch may snap to the other side dynamically depends on the initial speed of the attached mass due to impact. Sufficient condition on the initial speed against dynamic snap-through is formulated based on the concept of minimum energy barrier. The effects of damping on the transient response of the assembly are also discussed. An experimental setup is designed to measure the transient response of the arch following the impact and the critical initial speed of the attached mass. The experimental results are in good agreement with theoretical predictions.

scholarly journals Numerical simulation of GLARE 4A fiber-metal laminates subjected to ballistic impact

2018 ◽  
Vol 188 ◽  
pp. 01017
Author(s):  
George Bikakis ◽  
Nikolaos Tsigkros ◽  
Emilios Sideridis ◽  
Alexander Savaidis
Keyword(s):  
Impact Load ◽  
Impact Damage ◽  
Impact Resistance ◽  
Time History ◽  
Ballistic Impact ◽  
Fiber Metal Laminates ◽  
Ballistic Impacts ◽  
Fiber Metal ◽  
Force Time ◽  
The Impact

This article deals with the evaluation of the ballistic resistance of GLARE 4A fiber-metal laminates subjected to high velocity impact by a cylindrical projectile. Important impact variables such as the ballistic limit, the impact load and the absorbed energy time histories are predicted using the ANSYS LS-DYNA software. The simultaneous existence of various impact damage mechanisms, which is unique in fiber-metal laminates, is demonstrated using the numerical results. Each of the mechanisms absorbs a part of the initial impact energy and contributes to the high ballistic impact resistance the materials. With reference to the considered GLARE 4A panels, the behavior of the transient impact load is analyzed and useful conclusions are drawn. It is found that the maximum impact load is applied at the beginning of ballistic impacts, during the initial local indentation of the panels under the projectile. It is substantially higher than the following peak values of the impact force time history. It is revealed that during the beginning of ballistic impacts, the impulse of the collision increases as the thickness of the panels is increased. The work done by the impact load during the local indentation stage is also an increasing function of the panels’ thickness.

Use of Statical Indentation Laws in the Impact Analysis of Laminated Composite Plates

1985 ◽  
Vol 52 (1) ◽  
pp. 6-12 ◽  
Author(s):  
T. M. Tan ◽  
C. T. Sun
Keyword(s):  
Impact Analysis ◽  
Laminated Composite ◽  
Composite Plates ◽  
Impact Response ◽  
Low Velocity Impact ◽  
Low Velocity ◽  
The Impact ◽  
Theoretical Results ◽  
Theoretical Procedure ◽  
Good Agreement

The low-velocity impact response of graphite/epoxy laminates was investigated theoretically and experimentally. A nine-node isoparametric plate finite element in conjunction with an empirical contact law was used for the theoretical investigation. Theoretical results are in good agreement with strain-gage experimental data. The results of the investigation indicate that the present theoretical procedure describes the impact response of laminate for low-impact velocities.

A Comparative Study on the Impact Damage of Membrane Type LNGC Insulation System

2009 ◽  
Author(s):  
Min Sung Chun ◽  
Yong Suk Seo ◽  
Ito Hisasi ◽  
Wha Soo Kim ◽  
Byeong Jae Noh ◽  
...  
Keyword(s):  
Numerical Simulations ◽  
Failure Mode ◽  
Impact Load ◽  
Impact Damage ◽  
Structural Response ◽  
Structural Safety ◽  
Structural Behavior ◽  
Insulation System ◽  
Membrane Type ◽  
The Impact

To verify the structural safety under impact load caused by sloshing of LNG is one of the main issues in the design of membrane type LNG cargo containment system of LNG carrier. In order to estimate structural response under sloshing impact load, many kinds of studies including experimental test and numerical simulation have been done by various research groups such as shipyards, oil companies, universities as well as classification societies. In spite of these efforts, many uncertainties still exist to predict the structural behavior of LNG insulation system under sloshing impact load. Therefore, it can be regarded as a challenge to investigate dynamic response of LNG cargo insulation system against sloshing load. In this paper, Cooperative research results obtained by SHI-HHI-PNU-Lloyd-ABS-DNV JDP focused on the impact damage or failure mode of membrane type LNG cargo insulation system are summarized. A systematic experimental research is carried out to find out failure mode of the insulation system under impact load and criteria which can be applied for the design of LNG carrier. A series of dry drop tests as well as static compressive tests are carried out. The structural behavior of the specimen under impact load is recorded using ultrahigh-speed camera and reaction force is measured using load cells which are installed under bottom of the test facility. By analyzing recorded video, deformation history of the specimen at impact moment is obtained. The numerical simulations are also carried out for the dry drop test for verification purpose, It is expected that the insights observed from the systematic experiments and numerical simulations for the structural response of the LNG cargo insulation system subjected to the impact load can be effectively used as design guide for evaluation of the integrity of structural components of LNG cargo hold system.

Development and Impact Behaviors of AL Door Guarder Beam Reinforced with CFRP for Side Collision of Automobiles

2007 ◽  
Vol 334-335 ◽  
pp. 197-200 ◽  
Author(s):  
Yoshio Aoki ◽  
Goichi Ben ◽  
Yuka Iizuka
Keyword(s):  
Impact Load ◽  
Wide Field ◽  
Cfrp Laminates ◽  
Specific Strength ◽  
Reinforced Plastic ◽  
Automotive Structures ◽  
Reduce Carbon Dioxide ◽  
Side Collision ◽  
The Impact ◽  
Good Agreement

Carbon fiber reinforced plastic (CFRP) laminates are used in the wide field, because they have excellent properties of a specific strength and of a specific stiffness. The CFRP has a possibility of weight reduction automotive structures which can contribute to improve mileage and then to reduce Carbon dioxide. On the other hand, the safety of collision should be also made clear in the case of employing the CFRP to automotive structures. In this paper, the Al guarder beam reinforced with the CFRP is examined by an experiment and by a numerical analysis for replacing it to the conventional steel door guarder beam equipped in the automotive door. The experimental relations of impact load to displacement for the Al guarder beams with the different thickness of CFRP showed the good agreement with those of numerical results. From the comparison of these results, the numerical method developed here is quite useful for estimating the impact behaviors of Al guarder beam with CFRP layer.

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