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.

Application of air-bubble cushioning to improve the shock absorption performance of type I industrial helmets

2020 ◽  
Vol 117 ◽  
pp. 104921
Author(s):  
John Z. Wu ◽  
Christopher S. Pan ◽  
Mahmood Ronaghi ◽  
Bryan M. Wimer ◽  
Uwe Reischl
Keyword(s):  
Type I ◽  
Shock Absorption ◽  
Air Bubble ◽  
Absorption Performance

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.

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 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.

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.

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.

scholarly journals ANALISIS KEKUATAN TARIK KAMPUH V DAN KAMPUH I SAMBUNGAN LAS BAJA KARBON RENDAH YANG TERDAPAT PADA BESI IWF 400

2019 ◽  
Author(s):  
Irzal ◽  
syahrul
Keyword(s):  
Testing Machine ◽  
Material Testing ◽  
Test Machine ◽  
Type I ◽  
Average Value ◽  
Joint Connection ◽  
Connection Type ◽  
Universal Material Testing Machine ◽  
Material Testing Machine ◽  
Welding Position

by using connection type I. To get a good welding result is determined several factors, including the properties of material welding, connection type, welding position, and electrode used. In a welding project, there is still a welder that only uses I in the weld IWF 400 connecting iron while the thickness of the material 13 mm. This study aims to determine the effect of the use of campuh against the strength of weld joint connection using LB 52U 2.6 mm Electrode and RD 7018 3.2 mm electrode with AC Flow. In this study using experimental method begins with making specimens. With the collection of 7 specimens consisting of 3 specimens with welding treatment using Camp V, 3 specimens with welding treatment using Camp I and 1 IWF 400 specimens without welding treatment. From the results of research conducted on specimens by making and testing specimens with a tensile test machine Hydraullic Universal Material Testing Machine then obtained on the specimen without welding average value of Maximum (max) 41,28 kgf/mm². In welded specimens with a connection of the V values the average value of the Maximum (max) 39,82 kgf/mm². On a welded specimen with a maximum I knot connection (max) 38,32 kgf/mm².The results of this study indicate the results of iron welding IWF 400 using camp V greater value voltage 39.82 kgf / mm². From the maximum voltage value obtained from this study it is recommended that iron welding IWF 400 uses V.

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