Effects of shear-thickening polymer on force attenuation capacities in hip protectors

2021 ◽  
pp. 095440622110469
Author(s):  
Haeun Yum ◽  
Hamin Lim ◽  
Dahae Min ◽  
Chani Kwon ◽  
Jiin Seo ◽  
...  
Keyword(s):  
Polyurethane Foam ◽  
Impact Energy ◽  
Shear Thickening ◽  
Neck Region ◽  
Free Fall ◽  
Mechanical Tests ◽  
Energy Conditions ◽  
Hip Protector ◽  
Hip Protectors ◽  
The Impact

Many elderly people use hip protectors to prevent hip fractures from sideways falls. These hip protectors absorb or shunt away the energy applied to the greater trochanter. Herein, shear-thickening polymer (STP)-based hip protectors composed of STP and polyurethane foam are studied. The purpose of this study was to identify the main factor that reduces the impact force directly applied to the femoral neck region and to determine the optimal thickness of STP in hip protectors. Seven hip protectors of different thicknesses were prepared, and two sets of free-fall mechanical tests with a low impact energy of 25.1 J and moderate impact energy of 44.1 J were conducted for each hip protector. When the thickness of STP exceeded 8 mm, the resultant peak force tended to plateau under both impact conditions, and the force attenuation capacity decreased even under low impact energy conditions. Thus, a hip protector with a 6 mm or 8 mm STP and 5 mm foam was recommended. The STP was the key factor affecting force attenuation capacity, not the polyurethane foam. However, the foam also played an important role in helping the STP function and improving compliance for users.

scholarly journals Functionalization of silica particles to tune the impact resistance of shear thickening fluid treated aramid fabrics

RSC Advances ◽  
2017 ◽  
Vol 7 (78) ◽  
pp. 49787-49794 ◽  
Author(s):  
K. Talreja ◽  
I. Chauhan ◽  
A. Ghosh ◽  
A. Majumdar ◽  
B. S. Butola
Keyword(s):  
Energy Absorption ◽  
Impact Energy ◽  
Impact Resistance ◽  
Shear Thickening ◽  
Silica Particles ◽  
Modified Silica ◽  
Shear Thickening Fluid ◽  
Aramid Fabrics ◽  
And Control ◽  
The Impact

Kevlar fabrics treated with MTMS modified silica based STF showed better impact energy absorption as compared to APTES modified and control silica based STF treated fabrics, attributed to changes in interactions between fabrics and silica particles.

scholarly journals Factors Influencing the Rheological Properties of MRSP Based on the Orthogonal Experimental Design and the Impact Energy Test

2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
Bing Liu ◽  
Chengbin Du ◽  
Yankai Fu
Keyword(s):  
Impact Energy ◽  
Influence Factors ◽  
Shear Thickening ◽  
Orthogonal Experimental Design ◽  
Orthogonal Experiments ◽  
Relative Shear ◽  
Rate Of Increase ◽  
Magnetorheological Effect ◽  
Influence Degree ◽  
The Impact

In the preparation process of magnetorheological silly putty (MRSP), the influence factors of the relative shear thickening effect (RSE) and relative magnetorheological effect (RME) were studied by orthogonal experiments as well as range and variance analyses. The influence degree of each factor was also evaluated. The results showed that the viscosity of polydimethylsiloxane (PDMS) and the mass fraction of carbonyl iron powder (CIP) had a significant influence on the RSE and RME, respectively. With an increasing PDMS viscosity, the RSE of the silicon-boron copolymer matrix first increased and then decreased, while the RME of MRSP decreased gradually. In addition, the shear thickening mechanism of MRSP was explored by the molecular chain motion. Finally, the impact energy with different samples was tested, and it is demonstrated that with the increasing cross section, the impact energy of the sample increases gradually, but the rate of increase becomes smaller.

scholarly journals Effects of Rare Earth Elements (Ce, Y) on Microstructure and Mechanical Properties of P20 Die Steel

2021 ◽  
Vol 2101 (1) ◽  
pp. 012085
Author(s):  
Dan Wu ◽  
Qiang Hu ◽  
Wei Chen ◽  
Deping Lu ◽  
Jin Zou ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Rare Earth ◽  
Impact Energy ◽  
Mechanical Tests ◽  
Strength Increase ◽  
Die Steels ◽  
Matrix Microstructure ◽  
Microstructure And Mechanical Properties ◽  
The Impact

Abstract Electroslag remelting P20 die steels with different amount of CeO2 or Y2O3 additions have been investigated by using mechanical tests and scanning electronic microscope with energy dispersive spectrometry. The microstructure of P20 die steels is tempered martensite, in which plenty of carbides precipitate along the martensite laths. With addition of rare earth Ce or Y, the matrix microstructure is refined, the quantity of carbides is decreased, and the distribution of carbides becomes more uniform. As a result of these microstructural changes, both the impact energy and tensile strength increase with increasing rare earth content. The samples obtain optimum microstructure and mechanical properties when the amount of CeO2 or Y2O3 additions reach 4 wt.%. However, over-added CeO2 or Y2O3 (>4 wt.%) results in the increase of carbides quantity and the aggregation of carbides, which reduces the impact energy and tensile strength of the samples. Present study indicates that the optimum addition of CeO2 and Y2O3 for the P20 die steels is 4 wt.%.

scholarly journals EXPERIMENTAL AND ANALYTICAL STUDY ON THE IMPACT BEHAVIOR OF STEEL–CONCRETE COMPOSITE SLAB

2021 ◽  
Vol 12 (22) ◽  
pp. 1-13
Author(s):  
P Sangeetha ◽  
◽  
S Ramanagopal ◽  
R Manjula ◽  
T Hema Naga Sri Pushpa Swetha ◽  
...  
Keyword(s):  
Impact Energy ◽  
Composite Structures ◽  
Free Fall ◽  
Impact Behavior ◽  
Concrete Slabs ◽  
Cement Concrete ◽  
Shear Connectors ◽  
Analytical Results ◽  
Composite Slabs ◽  
The Impact

Concrete structures have been widely used for many years to resist impact loads. Steel–concrete composite structures may be considered efficient structures in the emerging modern construction field. Hence, the main objective of this research was to study the impact behavior of steel concrete composite slabs with different shear connectors and compare them with conventional slabs. Seven specimens of dimensions 500 × 500 × 50 mm were cast, which included plain cement concrete slabs, two reinforced cement concrete slabs with steel mesh and steel rebars as reinforcement, and four steel-concrete composite slabs with four different shear connectors: stud, tee, angle, and channel connectors. The composite action was achieved using a steel decking sheet welded with connectors on which the concrete layer was poured at the top. The test setup was fabricated with slots provided for specimens with simply supported end conditions and a mild steel drop weight. The specimens were impacted at the center of the span by dropping a steel mass from a free fall height of 1 m. The number of blows corresponding to the initial cracking and ultimate failure stages was recorded. The parameters that were used to compare the specimens were the impact energy absorbed, crack pattern, crack width, and increase in impact energy from the first blow to the last blow. The experimental results were very close to the analytical results obtained using ANSYS. The experimental and analytical results showed that the composite slabs with channel connectors performed better than the others, and it was proven that the composite slabs performed better under impact loading than conventional slabs.

scholarly journals Viscous-like forces control the impact response of shear-thickening dense suspensions

2021 ◽  
Vol 923 ◽  
Author(s):  
Marc-Andre Brassard ◽  
Neil Causley ◽  
Nasser Krizou ◽  
Joshua A. Dijksman ◽  
Abram. H. Clark
Keyword(s):  
Shear Thickening ◽  
Impact Response ◽  
Dense Suspensions ◽  
The Impact

Abstract

scholarly journals The Impact of Narrative Feedback, E-Learning Modules and Realistic Video and the Reduction of Misconception

2021 ◽  
Vol 11 (4) ◽  
pp. 158
Author(s):  
Abdul Halim ◽  
Elmi Mahzum ◽  
Muhammad Yacob ◽  
Irwandi Irwandi ◽  
Lilia Halim
Keyword(s):  
Biology Education ◽  
Free Fall ◽  
Percentage Reduction ◽  
Significant Treatment ◽  
Learning Modules ◽  
Physics Courses ◽  
Learning Platform ◽  
Quasi Experimental ◽  
E Learning ◽  
The Impact

Physics learning in universities utilized the Moodle-based e-learning media as an online learning platform. However, the effectiveness of remediating misconception using online media has not been widely researched. Therefore, this study was set to determine the level of misconception percentage reduction through the use of narrative feedback, the e-learning modules, and realistic video. The study was a quantitative approach with a quasi-experimental method involving 281 students who were taking basic physics courses in the Department of Physics, Chemistry, and Biology Education. The data collection used a three-tier diagnostic test based on e-learning at the beginning of the activity and after the treatment (posttest). The results of the data analysis with descriptive statistics show that the most significant treatment in reducing misconception percentage on the topic of free-fall motion was in the following order: narrative feedback, e-learning modules and realistic video. The misconception percentage reduction in the sub-concept of accelerated free- fall was effective for all types of the treatments.

Response and failure modes of biaxial warp-knitted flexible composite subject to low-velocity impact

2021 ◽  
pp. 152808372110154
Author(s):  
Ziyu Zhao ◽  
Tianming Liu ◽  
Pibo Ma
Keyword(s):  
Impact Energy ◽  
Linear Density ◽  
Failure Modes ◽  
Impact Response ◽  
Low Velocity Impact ◽  
Minor Effect ◽  
Low Velocity ◽  
Velocity Impact ◽  
Flexible Composites ◽  
The Impact

In this paper, biaxial warp-knitted fabrics were produced with different high tenacity polyester linear density and inserted yarns density. The low-velocity impact property of flexible composites made of polyurethane as matrix and biaxial warp-knitted fabric as reinforcement has been investigated. The effect of impactor shape and initial impact energy on the impact response of flexible composite is tested. The results show that the initial impact energy have minor effect on the impact response of the biaxial warp-knitted flexible composites. The impact resistance of flexible composite specimen increases with the increase of high tenacity polyester linear density and inserted yarns density. The damage morphology of flexible composite materials is completely different under different impactor shapes. The findings have theoretical and practical significance for the applications of biaxial warp-knitted flexible composite.

scholarly journals Impact resistance of steel materials to ballistic ejecta and shelter development using steel deck plates

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Hiroyuki Yamada ◽  
Kohei Tateyama ◽  
Shino Naruke ◽  
Hisashi Sasaki ◽  
Shinichi Torigata ◽  
...  
Keyword(s):  
Impact Energy ◽  
Impact Test ◽  
Impact Resistance ◽  
Protective Layer ◽  
High Strength ◽  
Steel Plates ◽  
Corrugated Plates ◽  
Shelter Construction ◽  
The Impact ◽  
Ballistic Ejecta

AbstractThe destruction caused by ballistic ejecta from the phreatic eruptions of Mt. Ontake in 2014 and Mt. Kusatsu-Shirane (Mt. Moto-Shirane) in 2018 in Japan, which resulted in numerous casualties, highlighted the need for better evacuation facilities. In response, some mountain huts were reinforced with aramid fabric to convert them into shelters. However, a number of decisions must be made when working to increase the number of shelters, which depend on the location where they are to be built. In this study, we propose a method of using high-strength steel to reinforce wooden buildings for use as shelters. More specifically, assuming that ballistic ejecta has an impact energy of 9 kJ or more, as in previous studies, we developed a method that utilizes SUS304 and SS400 unprocessed steel plates based on existing impact test data. We found that SUS304 is particularly suitable for use as a reinforcing material because it has excellent impact energy absorption characteristics due to its high ductility as well as excellent corrosion resistance. With the aim of increasing the structural strength of steel shelters, we also conducted an impact test on a shelter fabricated from SS400 deck plates (i.e., steel with improved flexural strength provided by work-hardened trapezoidal corrugated plates). The results show that the shelter could withstand impact with an energy of 13.5 kJ (2.66 kg of simulated ballistic ejecta at 101 m/s on impact). In addition, from the result of the impact test using the roof-simulating structure, it was confirmed the impact absorption energy is further increased when artificial pumice as an additional protective layer is installed on this structure. Observations of the shelter after the impact test show that there is still some allowance for deformation caused by projectile impact, which means that the proposed steel shelter holds promise, not only structurally, but also from the aspects of transportation and assembly. Hence, the usefulness of shelters that use steel was shown experimentally. However, shelter construction should be suitable for the target environment.

Force attenuation properties of shear-thickening polymer (STP)-based hip protector in simulated sideways fall

2020 ◽  
Vol 34 (12) ◽  
pp. 5351-5357
Author(s):  
Haeun Yum ◽  
Yeonha Kim ◽  
Bobae Kim ◽  
Yeokyeong Lee ◽  
Taeyong Lee
Keyword(s):  
Shear Thickening ◽  
Hip Protector ◽  
Sideways Fall
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