Predicting the Dynamic Properties of Plain Concrete Under the Impact Load

2019 ◽  
pp. 235-242
Author(s):  
Islem Megdiche ◽  
William Atherton ◽  
Clare Harris ◽  
Glynn Rothwell
Keyword(s):  
Impact Load ◽  
Dynamic Properties ◽  
Plain Concrete ◽  
The Impact

Experimental Study on Anti-Impact Properties of Prestressed Concrete Beams

2008 ◽  
Vol 400-402 ◽  
pp. 789-794
Author(s):  
Xin Wu Wang ◽  
Yan Zhao Li
Keyword(s):  
Prestressed Concrete ◽  
Impact Load ◽  
Dynamic Properties ◽  
Gravitational Potential Energy ◽  
Underground Structures ◽  
Analog Simulation ◽  
Impact Properties ◽  
Displacement Ductility ◽  
Load Carrying ◽  
The Impact

The dynamic displacement ductility and ultimate load-carrying capability of three partially prestressed concrete (PPC) and unbonded beams, has been experimentally investigated by applying impact load to their middle with falling hammers. The typical measurement wave curves are described. Influences of a falling hammer’s gravitational potential energy on the dynamic properties of the PPC beam are analyzed. Based on the analog simulation theory, the impact-load carrying capability of the actual unbonded PPC beam with span 12 m is gained. Results indicate that the unbonded PPC beams have favorable performance of anti-impact properties fragile destruction will not happen, and the unbonded PPC beams can be used in wide-span underground structures.

Failure Behavior of RC Slabs Subjected to Medium Velocity Impact

2016 ◽  
Author(s):  
Masuhiro Beppu ◽  
Shinnosuke Kataoka
Keyword(s):  
Shear Failure ◽  
Impact Load ◽  
Concrete Slab ◽  
Reaction Force ◽  
Plain Concrete ◽  
Concrete Specimen ◽  
Failure Behavior ◽  
Velocity Impact ◽  
Reinforced Concrete Slabs ◽  
The Impact

This study is intended to investigate failure mechanism of plain concrete and reinforced concrete slabs subjected to a medium-velocity impact by conducting impact tests. In a series of tests, a steel projectile with a mass of 8.3kg collided a concrete slab with a thickness of 18cm. In order to examine impact response of the concrete specimen, impact load and reaction force were measured. Test results revealed that the impact velocity corresponding to the scabbing limit was about 40m/s and the failure mode of the concrete specimen subjected to the medium-velocity was similar to the punching shear failure.

Manufacturing Capability of 3D Printed Stereolithography Parts for Impact Applications

2021 ◽  
Author(s):  
Anne Schmitz
Keyword(s):  
High Resolution ◽  
3D Printing ◽  
Impact Load ◽  
Dynamic Properties ◽  
Weight Bearing ◽  
Impact Resistance ◽  
Three Dimensional ◽  
Process Capability ◽  
Impact Testing ◽  
The Impact

Abstract Three-dimensional (3D) printing with high-resolution stereolithography (SLA) has grown in popularity for creating personalized medical devices. 3D printing is now starting to expand to weight-bearing components, e.g. prosthetic feet, as data on the dynamic properties impact and fatigue is published in the literature. The next step towards using 3D printing in impact applications is to assess the capability of the high-resolution SLA process to manufacture components of uniform impact resistance. Because impact testing is destructive, a surrogate measure to check a part's viability for resisting an impact load also needs to be established. Thirteen notched Izod specimens were printed on a Form2 SLA printer using the manufacturer's photocurable resins: clear, flexible, durable, and draft. Once all the specimens were printed, washed in isopropyl alcohol, and cured with ultraviolet light, the impact resistance was quantified using a pendulum impact tester in a notched Izod configuration. Then, the hardness of the specimens was quantified using a Shore durometer. The process capability indices of the impact resistance for the various polymers were 0.11 (clear), 0.43 (flexible), 0.65 (durable), and 1.07 (draft). Impact resistance and Shore durometer were only correlated for the flexible resin with a Spearman coefficient of r = 0.738, p < 0.005. Since the process capability index was so variable across materials, 3D printing with SLA polymers is not a viable manufacturing process for creating parts of consistent impact resistance. The current technology would lead to too many rejected parts.

scholarly journals Impact Resistance of High-Performance Steel Fiber Concrete under Long Term Exposure to Environmental Conditions

2018 ◽  
Vol 206 ◽  
pp. 02007
Author(s):  
Abdulhameed Umar Abubakar ◽  
Tulin Akçaoğlu ◽  
Khaled Marar
Keyword(s):  
Environmental Conditions ◽  
High Performance ◽  
Impact Load ◽  
Impact Resistance ◽  
Plain Concrete ◽  
Fiber Volume ◽  
Steel Fiber Concrete ◽  
Impact Energies ◽  
The Impact

An investigation is presented here that studied the influence of long-term environmental conditions exposure on cylindrical specimens after initial 28 day moist curing. The specimens were tested after six months subjected to Mediterranean weather elements in North Cyprus. Specimens with 150 mm diameter by 60 mm long cylinders were tested under impact load using a modified version of the testing equipment described in ACI 544.2R. Numbers of blows to create first and damage cracks were determined, and subsequently the impact energies calculated. It was seen that there is as much as twenty times improvement in impact energy of fibered concretes at fiber volume of 2% when compared with plain concrete. This will goa long way to improve the impact resistance of industrial floors and slabs on grade.

Impact Load Buffering Method Based on Stress Wave Attenuation Principle

2019 ◽  
Vol 11 (02) ◽  
pp. 1950019 ◽  
Author(s):  
Lin Gan ◽  
He Zhang ◽  
Cheng Zhou ◽  
Lin Liu
Keyword(s):  
Stress Wave ◽  
Wave Attenuation ◽  
Impact Load ◽  
Dynamics Simulation ◽  
Scanning System ◽  
Isolation Method ◽  
Element Analysis ◽  
System A ◽  
High Emission ◽  
The Impact

Rotating scanning motor is the important component of synchronous scanning laser fuze. High emission overload environment in the conventional ammunition has a serious impact on the reliability of the motor. Based on the theory that the buffer pad can attenuate the impact stress wave, a new motor buffering Isolation Method is proposed. The dynamical model of the new buffering isolation structure is established by ANSYS infinite element analysis software to do the nonlinear impact dynamics simulation of rotating scanning motor. The effectiveness of Buffering Isolation using different materials is comparatively analyzed. Finally, the Macht hammer impact experiment is done, the results show that in the experience of the 70,000[Formula: see text]g impact acceleration, the new buffering Isolation method can reduce the impact load about 15 times, which can effectively alleviate the plastic deformation of rotational scanning motor and improve the reliability of synchronization scanning system. A new method and theoretical basis of anti-high overload research for Laser Fuze is presented.

The impact of humic and fulvic acids on the dynamic properties of liposome membranes: the ESR method

2013 ◽  
Vol 24 (2) ◽  
pp. 106-112 ◽  
Author(s):  
Dariusz Man ◽  
Izabella Pisarek ◽  
Michał Braczkowski ◽  
Barbara Pytel ◽  
Ryszard Olchawa
Keyword(s):  
Dynamic Properties ◽  
Fulvic Acids ◽  
Humic And Fulvic Acids ◽  
The Impact

scholarly journals A Rational Numerical Method for Simulation of Drop-Impact Dynamics of Oleo-Pneumatic Landing Gear

2021 ◽  
Vol 11 (9) ◽  
pp. 4136
Author(s):  
Rosario Pecora
Keyword(s):  
Numerical Method ◽  
Initial Conditions ◽  
Impact Load ◽  
Numerical Models ◽  
Landing Gear ◽  
Design Stage ◽  
Impact Dynamics ◽  
State Variables ◽  
Adopted Model ◽  
The Impact

Oleo-pneumatic landing gear is a complex mechanical system conceived to efficiently absorb and dissipate an aircraft’s kinetic energy at touchdown, thus reducing the impact load and acceleration transmitted to the airframe. Due to its significant influence on ground loads, this system is generally designed in parallel with the main structural components of the aircraft, such as the fuselage and wings. Robust numerical models for simulating landing gear impact dynamics are essential from the preliminary design stage in order to properly assess aircraft configuration and structural arrangements. Finite element (FE) analysis is a viable solution for supporting the design. However, regarding the oleo-pneumatic struts, FE-based simulation may become unpractical, since detailed models are required to obtain reliable results. Moreover, FE models could not be very versatile for accommodating the many design updates that usually occur at the beginning of the landing gear project or during the layout optimization process. In this work, a numerical method for simulating oleo-pneumatic landing gear drop dynamics is presented. To effectively support both the preliminary and advanced design of landing gear units, the proposed simulation approach rationally balances the level of sophistication of the adopted model with the need for accurate results. Although based on a formulation assuming only four state variables for the description of landing gear dynamics, the approach successfully accounts for all the relevant forces that arise during the drop and their influence on landing gear motion. A set of intercommunicating routines was implemented in MATLAB® environment to integrate the dynamic impact equations, starting from user-defined initial conditions and general parameters related to the geometric and structural configuration of the landing gear. The tool was then used to simulate a drop test of a reference landing gear, and the obtained results were successfully validated against available experimental data.

scholarly journals Simulation Verification of the Contact Parameter Influence on the Forces’ Course of Cereal Grain Impact against a Stiff Surface

2021 ◽  
Vol 11 (2) ◽  
pp. 466
Author(s):  
Włodzimierz Kęska ◽  
Jacek Marcinkiewicz ◽  
Łukasz Gierz ◽  
Żaneta Staszak ◽  
Jarosław Selech ◽  
...  
Keyword(s):  
Dynamic Properties ◽  
Decisive Role ◽  
Force Sensor ◽  
Contact Forces ◽  
Correct Selection ◽  
Contact Parameter ◽  
Cereal Grain ◽  
Wide Range ◽  
The Impact ◽  
Selection Of

The continuous development of computer technology has made it applicable in many scientific fields, including research into a wide range of processes in agricultural machines. It allows the simulation of very complex physical phenomena, including grain motion. A recently discovered discrete element method (DEM) is used for this purpose. It involves direct integration of equations of grain system motion under the action of various forces, the most important of which are contact forces. The method’s accuracy depends mainly on precisely developed mathematical models of contacts. The creation of such models requires empirical validation, an experiment that investigates the course of contact forces at the moment of the impact of the grains. To achieve this, specialised test stations equipped with force and speed sensors were developed. The correct selection of testing equipment and interpretation of results play a decisive role in this type of research. This paper focuses on the evaluation of the force sensor dynamic properties’ influence on the measurement accuracy of the course of the plant grain impact forces against a stiff surface. The issue was examined using the computer simulation method. A proprietary computer software with the main calculation module and data input procedures, which presents results in a graphic form, was used for calculations. From the simulation, graphs of the contact force and force signal from the sensor were obtained. This helped to clearly indicate the essence of the correct selection of parameters used in the tests of sensors, which should be characterised by high resonance frequency.

scholarly journals Analysis on Force Transmission Characteristics of Two-Legged Shield Support under Impact Loading

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Qing-liang Zeng ◽  
Zhao-sheng Meng ◽  
Li-rong Wan ◽  
Cheng-long Wang
Keyword(s):  
Structural Design ◽  
Load Transfer ◽  
Impact Load ◽  
Force Transmission ◽  
Full Account ◽  
Flexible Bodies ◽  
Powered Support ◽  
Structural Design Optimization ◽  
Hinge Points ◽  
The Impact

To study the load transfer characteristics of a two-legged shield powered support, a numerical simulation model of the support was established using the multibody dynamics software ADAMS. The model took full account of the hydraulic-elastic deformation characteristics of the support, as a series spring-damper system was used to replace the leg and the equilibrium jack. The canopy, goaf shield, lemniscate bars, and equilibrium jack are equivalent to flexible bodies. The setting force of the leg was provided by the preload of the equivalent spring, the static roof load was simulated using a slope signal, and the impact load was simulated using a step signal. Using the model, the impact and excitation effects of each hinge joint of the support were analyzed under different impact load conditions across the canopy. The results show that the location of the impact load affects the force transmissions of all hinge points of the support. Both the impact effect and the excitation effect are at a minimum when the impact force is located near the leg action line. These results are useful for the adaptive control and structural design optimization of the support.

scholarly journals The influence of advance speed on overburden movement characteristics in longwall coal mining: insight from theoretical analysis and physical simulation

2021 ◽  
Vol 18 (1) ◽  
pp. 163-176
Author(s):  
Penghua Han ◽  
Cun Zhang ◽  
Zhaopeng Ren ◽  
Xiang He ◽  
Sheng Jia
Keyword(s):  
Physical Simulation ◽  
Impact Load ◽  
Main Roof ◽  
Longwall Face ◽  
Mine Safety ◽  
Efficient Production ◽  
Time Space ◽  
Mining Pressure ◽  
The Impact ◽  
Advance Speed

Abstract The advance speed of a longwall face is an essential factor affecting the mining pressure and overburden movement, and an effective approach for choosing a reasonable advance speed to realise coal mine safety and efficient production is needed. To clarify the influence of advance speed on the overburden movement law of a fully mechanised longwall face, a time-space subsidence model of overburden movement is established by the continuous medium analysis method. The movement law of overburden in terms of the advance speed is obtained, and mining stress characteristics at different advance speeds are reasonably explained. The theoretical results of this model are further verified by a physical simulation experiment. The results support the following conclusions. (i) With increasing advance speed of the longwall face, the first (periodic) rupture interval of the main roof and the key stratum increase, while the subsidence of the roof, the fracture angle and the rotation angle of the roof decrease. (ii) With increasing advance speed, the roof displacement range decreases gradually, and the influence range of the advance speed on the roof subsidence is 75 m behind the longwall face. (iii) An increase in the advance speed of the longwall face from 4.89 to 15.23 m/d (daily advancing of the longwall face) results in a 3.28% increase in the impact load caused by the sliding instability of the fractured rock of the main roof and a 5.79% decrease in the additional load caused by the rotation of the main roof, ultimately resulting in a 9.63% increase in the average dynamic load coefficient of the support. The roof subsidence model based on advance speed is proposed to provide theoretical support for rational mining design and mining-pressure-control early warning for a fully mechanised longwall face.

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