Impact Tests in an Air-Water Mixture

2017 ◽  
Author(s):  
Aboulghit El Malki Alaoui
Keyword(s):  
High Speed ◽  
Volume Fraction ◽  
Optical Probe ◽  
Test Machine ◽  
Water Mixture ◽  
Air Bubble ◽  
Impact Tests ◽  
Void Fractions ◽  
Shock Test Machine ◽  
The Impact

Experimental impact tests were performed using a shock machine and aerated water by means of an air-bubble generator. High speed shock test machine allows carrying out tests of impact on water (slamming). This machine permits to stabilise velocity with a maximal error equal to 10% during slamming tests. The air volume fraction in the bubble was measured by optical probe technique. The present work is aimed at quantifying the effects of the aeration on the hydrodynamic loads and pressures during the entry of a rigid body at constant speed in an air-water mixture. The impact tests were conducted with a rigid pyramid for an impact velocity equal to 15 m.s−1 and for two average void fractions, 0,46% and 0,84%. The reduction of the impact force and pressure due to aeration has been confirmed by these experiments.

Experimental investigation of the quasi-static and impact tests on the energy absorption characteristics of coupler rubber buffers used in railway vehicles

2018 ◽  
Vol 233 (9) ◽  
pp. 937-950 ◽  
Author(s):  
Shuguang Yao ◽  
Zhixiang Li ◽  
Wen Ma ◽  
Ping Xu ◽  
Quanwei Che
Keyword(s):  
Energy Absorption ◽  
Impact Velocity ◽  
High Speed ◽  
Compression Tests ◽  
Static Compression ◽  
Static Tests ◽  
Impact Tests ◽  
High Speed Trains ◽  
The Impact ◽  
Absorption Characteristics

Coupler rubber buffers are widely used in high-speed trains, to dissipate the impact energy between vehicles. The rubber buffer consists of two groups of rubbers, which are pre-compressed and then installed into the frame body. This paper specifically focuses on the energy absorption characteristics of the rubber buffers. Firstly, quasi-static compression tests were carried out for one and three pairs of rubber sheets, and the relationship between the energy absorption responses, i.e. Eabn  =  n ×  Eab1, Edissn =  n ×  Ediss1, and Ean =  Ea1, was obtained. Next, a series of quasi-static tests were performed for one pair of rubber sheet to investigate the energy absorption performance with different compression ratios of the rubber buffers. Then, impact tests with five impact velocities were conducted, and the coupler knuckle was destroyed when the impact velocity was 10.807 km/h. The results of the impact tests showed that with the increase of the impact velocity, the Eab, Ediss, and Ea of the rear buffer increased significantly, but the three responses of the front buffer did not increase much. Finally, the results of the impact tests and quasi-static tests were contrastively analyzed, which showed that with the increase of the stroke, the values of Eab, Ediss, and Ea increased. However, the increasing rates of the impact tests were higher than that of the quasi-static tests. The maximum value of Ea was 68.76% in the impact tests, which was relatively a high value for the vehicle coupler buffer. The energy capacity of the rear buffer for dynamic loading was determined as 22.98 kJ.

Impact Behaviour of Composite Materials by Using Low and High Speed Impact Tests

2012 ◽  
Vol 445 ◽  
pp. 189-194
Author(s):  
Enver Bulent Yalcin ◽  
Volkan Gunay ◽  
Muzeyyen Marsoglu
Keyword(s):  
Composite Materials ◽  
High Speed ◽  
Impact Test ◽  
Woven Fabrics ◽  
Impact Behaviour ◽  
High Speed Impact ◽  
Impact Tests ◽  
Data Acquisition Software ◽  
Damage Process ◽  
The Impact

The study presents the need for instrumented testing to optimizing materials against impact forces. The objective of the study is how the impact behaviour of composite materials is investigated by slow and high speed impact tests. Instron Dynatup 9250HV and Instron Dynatup 8150 Impact test machines (Fig.1.) are used which are located in TUBITAK-MRC, Materials Institute , Impact Test Laboratory". The damage process in composite materials under low and high velocity impact loading and the impact energy-displacement properties of the composite materials were investigated. Composite samples were produced by woven fabrics. The results are given as graphs and tables. The Impulse Data Acquisition software is used to send the data to computer.

Impact of Sulfur Pollution Silver Cage on Bearing Operating Performance

2010 ◽  
Author(s):  
Qingxiang Yang ◽  
Yulin Qi ◽  
Le Gu
Keyword(s):  
High Speed ◽  
Operating Performance ◽  
Silver Sulfide ◽  
Bench Test ◽  
Test Machine ◽  
Friction Property ◽  
Friction Test ◽  
The Impact ◽  
System Power ◽  
Financial Losses

Sulfur pollution on the silver cage leads to discoloration. Depot rework of silvered bearing cage caused by discoloration leads to great financial losses. In this paper, using a self-made high speed bearing bench test apparatus and the ball disc friction test machine assess the impact of sulfur pollution silver cage on bearing operating performance. The friction property of cage study on the ball disc friction test machine shows that the friction coefficient of silver sulfide film bearing cage is lower than that without pollution. The results from bearing bench test illustrates that the system power loss with sulfur pollution is slightly lower than that without pollution, and the sulfur pollution has little effect on bearing temperature rise. From the experimental results obtained, there is no necessary depot rework for the sulfur pollution sliver bearing cage from the perspective of the use of performance.

scholarly journals Solid–Liquid Composites with High Impact Resistance

2021 ◽  
Author(s):  
Miao Yu ◽  
Xiying Li ◽  
Pengyu Lv ◽  
Huiling Duan
Keyword(s):  
Energy Dissipation ◽  
High Speed ◽  
Volume Fraction ◽  
Split Hopkinson Pressure Bar ◽  
Impact Resistance ◽  
High Impact ◽  
Strain Rates ◽  
Dynamic Impact ◽  
Solid Liquid ◽  
The Impact

AbstractSolid–liquid composites (SLCs) with novel thermal/electronic/mechanical properties imparted by programmable and functional liquid inclusions have attracted considerable research interest in recent years, and are widely used in smart electronics and soft robotics. The feasible application of SLCs requires that they exhibit excellent static physical properties as well as dynamic impact resistance to satisfy complex service conditions, such as drops and impacts. This paper examined the impact resistance of SLCs fabricated by using microfluidic 3D printing. The results of dynamic split-Hopkinson pressure bar (SHPB) tests showed that the performance of the fabricated SLCs improved in terms of energy dissipation and impact resistance compared with pristine materials. In case of dynamic impact in the strain rates ranging from 100 to $$400\,\hbox {s}^{-1}$$ 400 s - 1 , the SLC specimen deformed without fracture, and its energy dissipation was dominated by the viscosity of the liquid inclusions. For dynamic impact in the strain rates ranging from 500 to $$800\,\hbox {s}^{-1}$$ 800 s - 1 , the SLC specimen fractured and its energy dissipation was determined by the volume fraction of the liquid inclusions. Thus, the energy dissipation of the SLCs could be tuned by regulating the viscosity and volume fraction of the liquid inclusions to satisfy the requirements of protection against different strain rates. Furthermore, the process of fracture of the SLCs under the dynamic SHPB tests was recorded and analyzed by using a high-speed camera. The results showed that distributed liquid inclusions changed the paths of crack propagation to enhance energy dissipation in the SLCs. This study experimentally verified the enhancement in the energy dissipation of SLCs, and provided design strategies for developing multifunctional SLCs with high impact resistance.

Study of Fracture Resistance of Nanolaminate Coatings Using Indentation and Impact Tests

2016 ◽  
Vol 258 ◽  
pp. 318-321 ◽  
Author(s):  
Vilma Buršíková ◽  
Jaroslav Sobota ◽  
Jan Grossman ◽  
Tomáš Fořt ◽  
Libor Dupák ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Magnetron Sputtering ◽  
Fracture Resistance ◽  
High Speed ◽  
High Speed Steel ◽  
Dynamic Impact ◽  
Impact Tests ◽  
Load Limit ◽  
Steel Substrates ◽  
The Impact

The aim of the present work was to study the mechanical properties of thin nanocomposite Mo-B-C coatings consisting of nanocrystalline Mo2BC embedded in amorphous Mo-B-C matrix. Magnetron sputtering of three targets, B4C, C and Mo, was used for coatings preparation. The Mo-B-C coatings were deposited on high speed steel substrates. The fracture resistance of Mo-B-C coatings was studied by both indentation and dynamic impact tests. The impact tests enabled us to predict the load limit causing the coating destruction.

Analysis of Stand-Up Forklift Operator Injuries in Off-the-Dock and Tip-Over Incidents With a Latched Door on the Operator Access Opening

2016 ◽  
Vol 2 (2) ◽  
Author(s):  
John F. Wiechel ◽  
William R. “Mike” Scott
Keyword(s):  
Head Injury ◽  
High Risk ◽  
High Speed ◽  
Neck Injury ◽  
Thoracic Injury ◽  
Shoulder Injury ◽  
Test Device ◽  
Impact Tests ◽  
Hybrid Iii ◽  
The Impact

A series of tip-over and off-the-dock impact tests were performed with stand-up forklifts to investigate the potential for injury to the operator of a forklift in these types of accidents, when the forklift is equipped with an operator’s compartment door. One Crown Equipment Company 35RRTT Model and one 35RCTT Model stand-up forklifts were used in the impact tests. The only modification to the forklifts for the tests was the placement of a door on the entrance to the operator’s compartment. A Hybrid III anthropomorphic test device (ATD) was placed in the operator’s compartment as a human surrogate. During each test, head accelerations, chest accelerations, neck loads, and lumbar loads were measured on the ATD. The motion of the forklift and the ATD were filmed with real-time video and high-speed cameras. Results from the impact tests indicate that there is a high risk of head injury in a right-side tip-over accident and a high risk of head injury and neck injury in a left-side tip-over accident. There is a high risk of a head injury, neck injury, and thoracic injury in off-the-dock forks-trailing accidents. In an off-the-dock forks-leading accident, there is a high risk of arm/shoulder injury, head injury, and neck injury. In both tip-over and off-the-dock forks-trailing accidents, there is a high probability of an entrapment injury under the overhead guard on the forklift.

scholarly journals Dynamic crack arrest capability of some metallic alloys and polymers

2018 ◽  
Vol 183 ◽  
pp. 02002
Author(s):  
Gunasilan Manar ◽  
Norazrina Mat Jali ◽  
Patrice Longère
Keyword(s):  
Impact Velocity ◽  
High Speed ◽  
Shear Failure ◽  
Failure Process ◽  
Shear Bands ◽  
Ductile Failure ◽  
Crack Arrest ◽  
Dynamic Crack ◽  
Impact Tests ◽  
The Impact

We are here interested in the crack arrest capability under impact loading of metals and polymers used as structural and/or protection materials in aerospace engineering. Kalthoff and Winkler-type impact tests are carried out to that purpose on high strength AA7175 aluminum alloy and shock resistant polymethyl methacrylate (PMMA). Impact tests are carried out at impact velocities ranging from 50 m/s to 250 m/s and high speed camera is used to record the different steps of the failure process. For AA7175, early Mode II shear failure followed by late Mode I opening failure are seen. The premature ductile failure of the alloy is shown to result from a preceding stage of dynamic localization in the form of adiabatic shear bands. Impact tests on shock-resistant PMMA evidence the brittle feature of the material failure. It is notably shown that the higher the impact velocity (in the range 50-100 m/s) the larger the number of fragments. Moreover, depending on the impact velocity, changes in the crack path and thus in the mechanisms controlling the PMMA dynamic fracture can be seen.

The Effect of an Operator Compartment Door on Standup Forklift Off-Dock and Tip-Over Injuries

2013 ◽  
Author(s):  
John F. Wiechel ◽  
William R. (Mike) Scott
Keyword(s):  
Head Injury ◽  
High Risk ◽  
High Speed ◽  
Neck Injury ◽  
Thoracic Injury ◽  
Shoulder Injury ◽  
Test Device ◽  
Impact Tests ◽  
Hybrid Iii ◽  
The Impact

A series of tip-over and off-the-dock impact tests were performed with stand-up forklifts in order to investigate the potential for injury to the operator of a forklift in these types of accidents when the forklift is equipped with an operator’s compartment door. One Crown Equipment Company RR Model and one RC Model stand-up forklift were used in the impact tests. The only modification to the forklifts for the tests was the placement of a door on the entrance to the operator’s compartment. A Hybrid III anthropomorphic test device (ATD) was placed in the operator’s compartment as a human surrogate. During each test, head accelerations, chest accelerations, neck loads and lumbar loads were measured on the ATD. The motion of the forklift and the ATD were filmed with video and high-speed cameras. Results from the impact tests indicate that there is a high risk of head injury in a right side tip-over accident and a high risk of head injury and neck injury in a left side tip-over accident. There is a high risk of a head injury, neck injury and thoracic injury in off-the-dock forks-trailing accidents. In an off-the-dock forks-leading accident there is a high risk of arm/shoulder injury, head injury, and neck injury. In both tip-over and off-the-dock forks-trailing accidents there is a high probability of an entrapment injury under the overhead guard on the forklift.

scholarly journals Resistance to Abrasive Wear and Volume Fraction of Carbides in Cast High-manganese Austenitic Steel with Composite Structure

2015 ◽  
Vol 15 (4) ◽  
pp. 129-133 ◽  
Author(s):  
G. Tęcza ◽  
J. Głownia
Keyword(s):  
Wear Resistance ◽  
Composite Structure ◽  
Abrasion Resistance ◽  
Volume Fraction ◽  
Hadfield Steel ◽  
Water Mixture ◽  
Vanadium Carbides ◽  
The Impact ◽  
High Manganese Austenitic Steel ◽  
Melt Solidification

Abstract Cast Hadfield steel is characterised by high abrasion resistance, provided, however, that it is exposed to the effect of dynamic loads. During abrasion without loading, e.g. under the impact of loose sand jet, its wear resistance drops very drastically. To increase the abrasion resistance of this alloy under the conditions where no pressure is acting, primary vanadium carbides are formed in the metallurgical process, to obtain a composite structure after the melt solidification. The primary, very hard, carbides uniformly distributed in the austenitic matrix are reported to double the wear resistance of samples subjected to the effect of a silicon carbide-water mixture.

scholarly journals Experimental and numerical investigation on the impact of vacuum level on effective thermal conductivity and microstructure of carbon fibre reinforced epoxy composites manufactured by vacuum bag method

2018 ◽  
Vol 240 ◽  
pp. 01015
Author(s):  
Michał Kubiś ◽  
Mirosław Seredyński ◽  
Łukasz Cieślikiewicz ◽  
Tomasz Wiśniewski ◽  
Anna Boczkowska
Keyword(s):  
Thermal Conductivity ◽  
Epoxy Resin ◽  
Effective Thermal Conductivity ◽  
Volume Fraction ◽  
Resin Composite ◽  
Vacuum Level ◽  
Void Fractions ◽  
Proposed Model ◽  
Analytical Formulae ◽  
The Impact

The physical properties of epoxy based carbon reinforced composites are highly anisotropic due to their directional structure and dependent on the manufacturing process parameters. Thermal conductivity was found to be dependent on the void volume fractions, which appear as a result of the insufficient vacuum level. In the proposed paper the multi-scale computational model of heat transfer across the carbon fiber-epoxy resin composite is proposed. The meso-scale effective thermal conductivities are determined with analytical formulae for isotropic and anisotropic media, the latter takes into account thermal resistance at the interface of fibres and epoxy resin. Proposed model is utilized to determine the effective thermal conductivity in the direction perpendicular to plies of composite. The influence of void fractions and the thickness of the composite on the effective thermal conductivity is investigated. The numerical outcomes underestimate the real variation in conductivity, which can be caused by change in carbon volume fraction of samples manufactured at different vacuum levels which was not considered in numerical computation.

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