scholarly journals Experimental Study on the Unsteady Characteristics and the Impact Performance of a High-Pressure Submerged Cavitation Jet

2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Yongfei Yang ◽  
Wei Li ◽  
Weidong Shi ◽  
Ling Zhou ◽  
Wenquan Zhang
Keyword(s):  
High Pressure ◽  
Impact Load ◽  
Cavitation Number ◽  
Small Range ◽  
Ocean Engineering ◽  
Nozzle Outlet ◽  
Impact Performance ◽  
Unsteady Characteristics ◽  
The Impact ◽  
Divergent Angle

High-pressure submerged cavitation jet is widely used in the fields of material peening, petroleum drilling, and ocean engineering. The impact performance of the jet with intensive cavitation is related to the factors such as working condition and the nozzle geometry. To reveal the relationship between the nozzle divergent angle and the jet pressure on the unsteady characteristics of the jet, high-speed photography with frame rate of 20000 fps is used to record the image of the cavitation clouds. Grayscale analysis algorithm developed in MATLAB is used to study the effects of injecting condition on the special structure, unsteady characteristics, and shedding frequency of the cavitation bubbles. The impact load characteristics of the cavitation jet with different cavitation numbers and stand-off distances are recorded using a high-response pressure transducer. It is found that the cavitation number is the main factor affecting the cavitation morphology of the submerged jet. The lower the cavitation number is, the more intense the cavitation occurs. The outlet divergent angle of the convergent-divergent nozzle also has a significant influence on the development of the cavitation clouds. In the three nozzles with the outlet divergent angles of 40°, 80°, and 120°, the highest bubble concentration is formed usinga nozzle with a divergent angle of 40°, but the high-concentration cavitating bubbles are only distributed in a very small range of the nozzle outlet. The cavities generated by using the nozzle with a divergent angle of 80° can achieve good results in terms of concentration and distribution range, while the nozzle with divergent angle of 120° has lower cavitation performance due to the lack of the constraint at the outlet which intensifies the shear stress of the jet. According to the result of frame difference method (FDM) analysis, the jet cavitation is mainly formed in the vortex structure generated by the shearing layer at the nozzle exit, and the most severe region in the collapse stage is the rear end of the downstream segment after the bubble cloud sheds off. The impact load of the cavitation jet is mainly affected by the stand-off distance of the nozzle from the impinged target, while the nozzle outlet geometry also has an effect on the impact performance. Optimizing the stand-off distance and the outlet geometry of the nozzles is found to be a good way to improve the performance of the cavitation jet.

Study on the Impact Response of Concrete Filled FRP-Steel Tube Structures

2011 ◽  
Vol 368-373 ◽  
pp. 549-552
Author(s):  
Chen Chen ◽  
Ying Hua Zhao ◽  
Chun Yang Zhu ◽  
Li Wei
Keyword(s):  
Impact Load ◽  
Steel Tube ◽  
Fiber Reinforced Polymer ◽  
Experimental Result ◽  
Lateral Impact ◽  
Steel Tubes ◽  
Impact Performance ◽  
Reinforced Polymer ◽  
The Impact ◽  
Frp Sheet

This paper studies the impact performance of concrete filled FRP-steel tube which is a composed structure made by filling concrete into steel tube and wrapping outside with fiber reinforced polymer (FRP) sheet. Numerical simulations have been conducted to study the dynamic response of fixed-pined supported beams of concrete filled FRP-steel tubes. The finite element models of concrete filled FRP-steel tubes are established to analyse its lateral impact dynamic characteristics under different loading situations, with respective kinds of FRP and thicknesses of steel tubes. The impact force and displacement histories were recorded. Comparing to the traditional concrete filled steel tube structure, the concrete filled FRP-steel tube indicates a promising structure with more advantages in the mechanical and constructional performance. Especially with its higher loading-carrying capacity and better toughness, it is more adaptable for the structures subjected to accidental impact load. Analytical solution is compared with experimental result to show the correctness and the effectiveness of present study.

Experimental Investigation of Ice Mass Hydrodynamic Interaction With Offshore Structure in Close Proximity

2015 ◽  
Author(s):  
Tanvir Mehedi Sayeed ◽  
Bruce Colbourne ◽  
Heather Peng ◽  
Benjamin Colbourne ◽  
Don Spencer
Keyword(s):  
Hydrodynamic Interaction ◽  
Impact Load ◽  
Numerical Study ◽  
Numerical Models ◽  
Offshore Structures ◽  
Ocean Engineering ◽  
Offshore Structure ◽  
Area Of Interest ◽  
Close Proximity ◽  
The Impact

Iceberg/bergy bit impact load with fixed and floating offshore structures and supply ships is an important design consideration in ice-prone regions. Studies tend to divide the iceberg impact problem into phases from far field to contact. This results in a tendency to over simplify the final crucial stage where the structure is impacted. The authors have identified knowledge gaps and their influence on the analysis and prediction of iceberg impact velocities and loads (Sayeed et. al (2014)). The experimental and numerical study of viscous dominated very near field region is the main area of interest. This paper reports preliminary results of physical model tests conducted at Ocean Engineering Research Center (OERC) to investigate hydrodynamic interaction between ice masses and fixed offshore structure in close proximity. The objective was to perform a systematic study from simple to complex phenomena which will be a support base for the development of subsequent numerical models. The results demonstrated that hydrodynamic proximity and wave reflection effects do significantly influence the impact velocities at which ice masses approach to large structures. The effect is more pronounced for smaller ice masses.

scholarly journals Experimental Study on Submerged High-Pressure Jet and Parameter Optimization for Cavitation Peening

Mechanika ◽  
2020 ◽  
Vol 26 (4) ◽  
pp. 346-353
Author(s):  
Yongfei YANG ◽  
Wei LI ◽  
Weidong SHI ◽  
Chuan WANG ◽  
Wenquan ZHANG
Keyword(s):  
High Pressure ◽  
High Speed ◽  
Surface Profile ◽  
304 Stainless Steel ◽  
Nozzle Geometry ◽  
High Speed Photography ◽  
Sem Images ◽  
Before And After ◽  
The Impact ◽  
Divergent Angle

To increase the performance of high pressure submerged cavitation jet that has been used for cavitation peening, the effect of stand-off distance and the nozzle geometry on the impact capacity is investigated and optimized. High speed photography of the cavitation bubble clouds taken to reveal the unsteady characteristics of the cavitating jet. The impact ability of the jet with different nozzles and standoff distance is tested using Al 1060 at first, and the optimized jet is used then for cavitation peening on 304 stainless steel. The surface profile as well as the grain structures before and after peening using different nozzles are observed from SEM images. It is found that, the divergent angle of the nozzle has a great effect on the impact capability of the submerged high-pressure jet, which is important for improving the peening efficiency. In the nozzles with divergent angle 40°, 60° and 80°, the 60° nozzle shows the best performance. After peening, grain cells under the metal surface are changed and a twin layer is formed. The current research reveals the transient characteristics of the submerged cavitation jet and main factors that affect its impact rate, which provides guide for the nozzle design and application for the high-pressure cavitation jet peening.

Impact Performance of Low Carbon Steel Safety Beams for Car Doors

2012 ◽  
Vol 165 ◽  
pp. 247-251
Author(s):  
A.A. Lashlem ◽  
Dzuraidah Abd Wahab ◽  
Shahrum Abdullah ◽  
Che Hassan Che Haron
Keyword(s):  
Carbon Steel ◽  
Energy Absorption ◽  
Impact Load ◽  
Low Carbon Steel ◽  
Low Carbon ◽  
Element Analysis ◽  
Impact Performance ◽  
Beam Design ◽  
The Impact ◽  
Impact Absorption

This paper presents impact behaviour and energy absorption response of car door safety beams. Low carbon steel of thickness 2.25 mm, designed into four different shapes of, tube-beam, I-beam and II-beam were used in this experiment to study the effect of impact load on the crash characteristic of the door beams in terms of load bearing and attenuation of energy. The tube-beam is the conventional beam commonly used in cars today. The reason propelling the investigation of other beams is to draw a parallel comparison with the conventional tube beam and possibly obtain an optimised design in terms of impact absorption capability. Masses of impactors used in the impact load simulations were 10 kg, 20 kg, 30 kg, 40 kg and 50 kg at an impact speed of 30 km/h. Analysis were carried out on all samples focusing on energy absorption and deformation characteristics of the beam structures using Pam CrashTM finite element analysis software. Results from this studies indicated that the II-beam design is better than the other beams in terms of the energy absorption and deformation. The proposed II-beam design may be able to prolong the useful life of passenger car door.

Effect of Temperature on the Impact Performance of Short Fiber Reinforced Composites

2010 ◽  
Vol 458 ◽  
pp. 75-80
Author(s):  
Fu You Wang ◽  
Guo Li Zhang ◽  
Jia Lu Li ◽  
Yu Feng Zhang ◽  
L. Chen ◽  
...  
Keyword(s):  
Composite Materials ◽  
Glass Fiber ◽  
Temperature Increase ◽  
Impact Load ◽  
Fiber Reinforced Composites ◽  
Reinforced Composites ◽  
Fiber Reinforced ◽  
Impact Performance ◽  
Glass Fiber Reinforced ◽  
The Impact

In order to test the impact performance of short glass fiber reinforced composite materials in different temperature, on the basis of molding process, the specimens of polypropylene modified resin based glass fiber reinforced composites were made, the impact performance of the materials with the different temperature of -35°C, 23°C and 80°C were tested. Results show that the maximum load of specimen can bear is gradually increased with the temperature increase, and the maximum impact load of specimen is 0.8722kN at -35°C, while the maximum impact load which is improved 38% is 1.2024kN at 80°C. Also the energy absorbed by composite materials increase with the temperature increase. Results also show that the composite materials manifest as plastic fracture in high temperatures and brittle fracture in low temperatures.

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.

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.

Multiple orifices in customized microsystem high-pressure emulsification: The impact of design and counter pressure on homogenization efficiency

2014 ◽  
Vol 248 ◽  
pp. 107-121 ◽  
Author(s):  
Jan Henrik Finke ◽  
Svea Niemann ◽  
Claudia Richter ◽  
Thomas Gothsch ◽  
Arno Kwade ◽  
...  
Keyword(s):  
High Pressure ◽  
Counter Pressure ◽  
The Impact

scholarly journals Single Crystal Growth and Physical Properties of Pyroxene CoGeO3

Crystals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 378
Author(s):  
Li Zhao ◽  
Zhiwei Hu ◽  
Hanjie Guo ◽  
Christoph Geibel ◽  
Hong-Ji Lin ◽  
...  
Keyword(s):  
High Pressure ◽  
Magnetic Properties ◽  
Magnetic Susceptibility ◽  
Crystal Growth ◽  
Physical Properties ◽  
Single Crystal ◽  
Single Crystals ◽  
Magnetic Moments ◽  
Single Crystal Growth ◽  
The Impact

We report on the synthesis and physical properties of cm-sized CoGeO3 single crystals grown in a high pressure mirror furnace at pressures of 80 bar. Direction dependent magnetic susceptibility measurements on our single crystals reveal highly anisotropic magnetic properties that we attribute to the impact of strong single ion anisotropy appearing in this system with TN∼33.5 K. Furthermore, we observe effective magnetic moments that are exceeding the spin only values of the Co ions, which reveals the presence of sizable orbital moments in CoGeO3.

scholarly journals Impact Resistance of Epoxy Composites Reinforced with Amazon Guaruman Fiber: A Brief Report

Polymers ◽  
2021 ◽  
Vol 13 (14) ◽  
pp. 2264
Author(s):  
Raphael H. M. Reis ◽  
Fabio C. Garcia Filho ◽  
Larissa F. Nunes ◽  
Veronica S. Candido ◽  
Alisson C. R. Silva ◽  
...  
Keyword(s):  
Fiber Composite ◽  
Impact Resistance ◽  
Fiber Composites ◽  
Epoxy Composites ◽  
Impact Performance ◽  
Electron Microscopy Analysis ◽  
Ballistic Properties ◽  
Microscopy Analysis ◽  
Izod Impact ◽  
The Impact

Fibers extracted from Amazonian plants that have traditionally been used by local communities to produce simple items such as ropes, nets, and rugs, are now recognized as promising composite reinforcements. This is the case for guaruman (Ischinosiphon körn) fiber, which was recently found to present potential mechanical and ballistic properties as 30 vol% reinforcement of epoxy composites. To complement these properties, Izod impact tests are now communicated in this brief report for similar composites with up to 30 vol% of guaruman fibers. A substantial increase in impact resistance, with over than 20 times the absorbed energy for the 30 vol% guaruman fiber composite, was obtained in comparison to neat epoxy. These results were statistically validated by Weibull analysis, ANOVA, and Tukey’s test. Scanning electron microscopy analysis disclosed the mechanisms responsible for the impact performance of the guaruman fiber composites.

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