scholarly journals Experimental Study on the Shock Absorption Performance of Combined Aluminium Honeycombs under Impact Loading

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Lei Cao ◽  
Yuliang Lin ◽  
Fangyun Lu ◽  
Rong Chen ◽  
Zhifeng Zhang ◽  
...  
Keyword(s):  
Response Curves ◽  
Shock Absorption ◽  
Maximum Acceleration ◽  
Static State ◽  
Testing Platform ◽  
Compression Properties ◽  
Acceleration Sensors ◽  
Absorption Performance ◽  
Test Points ◽  
Absorption Level

Shock absorption characteristics of combined aluminium honeycomb structures were studied experimentally. In the experiments, a testing platform was design to compare the shock absorption level of different honeycomb specimens quantitatively. The shock response curves of six test points mounted on the platform were recorded with acceleration sensors when the buffer was impacted by a bullet driven by high pressure gas. The maximum acceleration values in time domain and in specifically spectral domain were obtained based on spectral analysis. Comparing the data of combined aluminium honeycomb buffer and single aluminium honeycomb buffer, conclusion can be obtained that shock absorbing characteristic of combined aluminium honeycomb buffer is better. Furthermore, compression properties of three kinds of buffers were tested under quasi-static state. The energy absorption parameters were calculated. The results show suitable combined aluminium honeycomb buffer can smooth the stress and lower the energy applied to the testing platform.

scholarly journals High-Speed impact experiment for evaluation of magnetorheological fluid’s shock-absorption performance

2018 ◽  
Vol 183 ◽  
pp. 04008
Author(s):  
Yuya Mitani ◽  
Takahiro Yano ◽  
Takuyoh Hagi ◽  
Keiko Watanabe ◽  
Koji Fukudome
Keyword(s):  
Kinematic Viscosity ◽  
High Speed ◽  
Silicone Oil ◽  
Tap Water ◽  
Shock Absorption ◽  
Mr Fluid ◽  
High Speed Impact ◽  
Smart Fluids ◽  
Absorption Performance ◽  
Mr Effect

Magnetorheological (MR) fluids are categorized as smart fluids, which are made of small iron particles suspended in carrier fluids such as silicone oil. The presence of a magnetic field will instantaneously increase the viscosity of the MR fluid, also known as the MR effect. The application of the MR fluid as viscous dampers to automobiles and buildings has shown excellent performance in shock absorption. To expand the practical application of the MR fluid, various evaluations of shock-absorption performance under high-loading conditions are needed. Therefore, we decided to investigate its performance in high-speed impact conditions. Impact experiments were conducted in different liquids—tap water, two types of silicone oils with different kinematic viscosities, and an MR fluid—and it was investigated how the properties of each liquid affect the shock-absorption performance. Accordingly, it was found that kinematic viscosity and compressibility affect shock-absorption performance. The kinematic viscosity did not affect the speed attenuation of the projectile. Furthermore, it was found that the compressibility affected the pressure wave generated by the entry of a projectile into the liquid.

scholarly journals Application of polyethylene air-bubble cushions to improve the shock absorption performance of Type I construction helmets for repeated impacts

2020 ◽  
pp. 1-14
Author(s):  
John Z. Wu ◽  
Christopher S. Pan ◽  
Mahmood Ronaghi ◽  
Bryan M. Wimer ◽  
Uwe Reischl
Keyword(s):  
Structural Damage ◽  
Endurance Limit ◽  
Drop Impact ◽  
Test Machine ◽  
Type I ◽  
Drop Height ◽  
Shock Absorption ◽  
Air Bubble ◽  
Absorption Performance ◽  
Repeated Impacts

BACKGROUND: The use of helmets was considered to be one of the important prevention strategies employed on construction sites. The shock absorption performance of a construction (or industrial) helmet is its most important performance parameter. Industrial helmets will experience cumulative structural damage when being impacted repeatedly with impact magnitudes greater than its endurance limit. OBJECTIVE: The current study is to test if the shock absorption performance of Type I construction helmets subjected to repeated impacts can be improved by applying polyethylene air-bubble cushions to the helmet suspension system. METHODS: Drop impact tests were performed using a commercial drop tower test machine following the ANSI Z89.1 Type I drop impact protocol. Typical off-the-shelf Type I construction helmets were evaluated in the study. A 5 mm thick air-bubble cushioning liner was placed between the headform and the helmet to be tested. Helmets were impacted ten times at different drop heights from 0.61 to 1.73 m. The effects of the air-bubble cushioning liner on the helmets’ shock absorption performance were evaluated by comparing the peak transmitted forces collected from the original off-the-shelf helmet samples to the helmets equipped with air-bubble cushioning liners. RESULTS: Our results showed that a typical Type I construction helmet can be subjected to repeated impacts with a magnitude less than 22 J (corresponding to a drop height 0.61 m) without compromising its shock absorption performance. In comparison, the same construction helmet, when equipped with an air-bubble cushioning liner, can be subjected to repeated impacts of a magnitude of 54 J (corresponding to a drop height 1.52 m) without compromising its shock absorption performance. CONCLUSIONS: The results indicate that the helmet’s shock absorbing endurance limit has been increased by 145% with addition of an air-bubble cushioning liner.

scholarly journals Analysis and Design of a Novel Concept Gasket to Improve the Reliability of the Balanced Armature Receiver Used in Earphones

2019 ◽  
Vol 9 (18) ◽  
pp. 3661
Author(s):  
Zhi-Xiong Jiang ◽  
Jun-Hyung Kim ◽  
Yuan-Wu Jiang ◽  
Dan-Ping Xu ◽  
Sang-Moon Hwang
Keyword(s):  
Harmonic Distortion ◽  
Von Mises Stress ◽  
Shock Absorption ◽  
Analysis And Design ◽  
Absorption Performance ◽  
Novel Concept ◽  
Von Mises ◽  
External Forces ◽  
Drop Impacts ◽  
Drop Impact Test

Currently, balanced armature (BA) receivers are frequently used in earphones, owing to their small size and superior sound quality. However, the reliability of BA receiver earphones has become a considerable challenge, as they easily fail when subjected to external forces, especially during drop impacts. In addition, the original gasket cannot protect the BA receiver well. Therefore, this article focuses on improving the reliability of BA receiver earphones by designing a novel concept for the gasket. Based on a simplified model and analysis methods, the maximum von Mises stress on the armature with different drop directions and the maximum von Mises stress point must first be determined. The gasket was divided into two parts, one for linking and the other for shock absorption. This article focused on the design of the shock absorption structure. A novel concept gasket was proposed, and the analysis results showed that the gasket improved the shock absorption performance. For demonstrating the validity of the shock absorption performance of the novel concept gasket, three confirmatory experiments were performed: the drop impact test, X-ray photography, and sound performance, which included the sound pressure level and total harmonic distortion. The analysis results were experimentally verified.

Research on Compression and Rebounding of the Zoom Air in Sport-Shoes

2011 ◽  
Vol 55-57 ◽  
pp. 1875-1879
Author(s):  
Wen Li Peng ◽  
Lei Lu ◽  
Wen Ni Zhang
Keyword(s):  
Shock Absorption ◽  
Energy Feedback ◽  
Absorption Energy ◽  
Essential Change ◽  
Absorption Performance

Today, the zoom air was widely used in top grade sport-shoes. Firstly, the function of zoom air, including shock absorption, energy return, light quantization and ornament results were introduced. Secondly, the problem of using the zoom air nowadays was brought forward, through testing the compression and rebounding of the zoom air in sport-shoes, the shock absorption and the energy return of it were researched. The factors of influencing the compression and rebounding of the zoom air were discussed from speed of the athletics and the aging of the zoom air. The speed had effect on the shock absorption performance and energy return performance. The faster the speed was, the smaller the protection the zoom air could offer and the energy feedback were. Ageing would not make the material of the zoom air produce essential change, but may cause the reduction of the gas in the zoom air. All performances of the zoom air were improved after ageing, which means the zoom air in the market was not optimum at present, all this contributed to the lack of united standard. Finally, the method of testing and the standard of evaluation were put forward, which did some early work for the standard of zoom air in producing and testing.

Experimental Investigation on Absorption Performance of Nanofluids for CO2 Capture

2020 ◽  
Vol 28 (02) ◽  
pp. 2050017 ◽  
Author(s):  
Basavaraj Devakki ◽  
Shijo Thomas
Keyword(s):  
Carbon Dioxide ◽  
Salt Concentration ◽  
Initial Pressure ◽  
Operating Conditions ◽  
Absorption Test ◽  
Static State ◽  
Relative Absorption ◽  
Absorption Performance ◽  
The Stability ◽  
Stainless Steel 316

Lately, absorption of carbon dioxide using nanofluids has gained more attention as this acidic gas creates global warming effect. The absorption test was conducted in a custom designed high-pressure vessel made up of stainless steel 316 L, where CO2 and nanofluid are in direct contact at static state. The type of nanoparticles and influence of its concentration on absorption of carbon dioxide are analyzed. TiO2 and Al2O3 nanofluids at 0.02–0.14[Formula: see text]wt.% concentrations are prepared by dispersing in DI water. The CO2 absorption tests were carried out for the above-mentioned nanofluids at said concentrations with operating conditions being an initial pressure of 3 bar and initial temperature of 302[Formula: see text]K. The results show that relative absorption index (RAI) of CO2 absorption has increased to a maximum and then decreased with increase in nanoparticle concentration. The aqueous-based TiO2, Al2O3 nanofluids are found to be most effective at 0.1 and 0.14[Formula: see text]wt.%, respectively, with RAI showing 39.81% and 22.3% increase in CO2 absorption as compared to basefluid, respectively. The absorption test has also been conducted for saline-based TiO2 and Al2O3 nanofluids at 1, 2, 3 and 3.1[Formula: see text]wt.% of salt concentration. The stability of saline-based nanofluids was analyzed using turbidity meter. It was found that increase in salt concentration decreases the stability of nanofluids and also decreases the CO2 absorption rate because of unstability of nanoparticles in salt solutions. Absorption decreased by 11.93% for TiO2, and 5.68% for Al2O3, when salt concentration was increased from 1 to 3.1[Formula: see text]wt.%.

The Evaluation of Absorption Performance of Magneto-Rheological (MR) Elastomer

2015 ◽  
Vol 1095 ◽  
pp. 483-489
Author(s):  
Kwang Hee Lee ◽  
Kyung Sik Jung ◽  
Chul Hee Lee
Keyword(s):  
Magnetic Field ◽  
Mechanical Properties ◽  
Impact Test ◽  
Impact Load ◽  
Time Duration ◽  
Shock Absorption ◽  
Absorption Performance ◽  
Magneto Rheological ◽  
Drop Impact Test ◽  
The Magnetic Field

This study examines the relation between the thickness of a specimen and the weight of an impactor for evaluating the shock absorption performance of magneto-rheological (MR) elastomers with and without a magnetic field. The shock absorption performance can be evaluated by calculating impact energy. The MR elastomer is a smart material and its mechanical properties change under the influence of a magnetic field. The drop impact test is performed to evaluate the amount of shock absorption of the MR elastomer for each test condition. Tests are also performed by varying the magnetic field during impact to improve the shock absorption performance of the MR elastomer, which is related to impact load. The results show a better shock absorption performance with a thicker MR elastomer, lighter impactor, and without a magnetic field. Also, the magnitude of impact and the time duration for stabilization are improved when the magnetic field is varied during the test.

Sound absorption and compression properties of perpendicular-laid nonwovens

2018 ◽  
Vol 89 (4) ◽  
pp. 612-624 ◽  
Author(s):  
Tao Yang ◽  
Xiaoman Xiong ◽  
Rajesh Mishra ◽  
Jan Novák ◽  
Jiří Militký
Keyword(s):  
Fiber Orientation ◽  
Sound Absorption ◽  
Orientation Angle ◽  
Areal Density ◽  
Frequency Range ◽  
Pressing Method ◽  
Compression Properties ◽  
Fiber Orientation Angle ◽  
Absorption Performance ◽  
Manufacturing Techniques

This study presents an investigation into the sound absorption behavior and compression properties of perpendicular-laid nonwovens. Seven types of perpendicular-laid nonwovens produced by vibrating and rotating perpendicular lappers were selected. Nonwovens with varying thickness and areal density were prepared by the heat-pressing method to investigate the effect of structural parameters such as thickness and areal density on sound absorption ability. Measurements of sound absorption properties were carried out with a Brüel and Kjær measuring instrument. The effect of manufacturing techniques on sound absorption performance and compression properties was investigated. The effect of porosity on sound absorption ability was studied. The influence of density and fiber orientation angle on compression properties was analyzed. The results show that samples prepared by vibrating perpendicular lapper exhibit better compression properties, whereas there is no significant influence of two manufacturing techniques on sound absorption performance. The increase of areal density results in improvement in the sound absorption ability. The increase of thickness can improve the sound absorption coefficient in the low-frequency range, but decrease of the coefficient occurred in the high-frequency range. A quadratic relationship between porosity and sound absorption ability has been found. The results also show that compressional resistance has a strong relation with density – the correlation coefficient is 0.95, indicating that the compressional resistance is directly proportional to the density of perpendicular-laid nonwovens. The results indicate that the perpendicular-laid nonwovens with higher initial fiber orientation angle have better compression properties.

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