Enhanced energy absorption characteristics of novel integrated hybrid honeycomb/polystyrene foam

2020 ◽  
pp. 0021955X2096521
Author(s):  
Somen K Bhudolia ◽  
Goram Gohel ◽  
Kah Fai Leong
Keyword(s):  
Energy Absorption ◽  
Head Injuries ◽  
Honeycomb Structure ◽  
Expanded Polystyrene ◽  
Absorption Characteristic ◽  
Elastic Buckling ◽  
Bicycle Helmet ◽  
Polystyrene Foam ◽  
Additional Energy ◽  
Weight Property

Expanded Polystyrene (EPS) is commonly used as an inner liner for a bicycle helmet due to its outstanding energy absorption characteristic and light-weight property. The current investigation presents a novel technique to manufacture hybrid EPS/honeycomb structure foam using an integrated manufacturing approach to further enhance the energy dissipation properties for improved safety against head injuries. Different foam designs were analysed under curb-stone impact tests and the failure mechanisms are deliberated. Integrated EPS-honeycomb hybrid liners have shown up to 20% higher energy absorption, with the additional energy being absorbed in associated densification of foam and the elastic buckling features of the honeycomb.

Impact performance of innovative corrugated polystyrene foam for bicycle helmets

2020 ◽  
pp. 0021955X2096521
Author(s):  
Somen K Bhudolia ◽  
Goram Gohel ◽  
Kah Fai Leong
Keyword(s):  
Energy Absorption ◽  
High Speed ◽  
Head Injuries ◽  
Expanded Polystyrene ◽  
The Novel ◽  
Comparison Study ◽  
Impact Performance ◽  
Bicycle Helmets ◽  
Weight Property ◽  
The Impact

Expanded Polystyrene (EPS) is a common material used to manufacture the inner foam liner of a bicycle helmet due to its outstanding energy absorption characteristics and light-weight property. The current research presents a novel corrugated expanded polystyrene (EPS) foam design concept which is used to enhance the impact dissipation of bicycle helmets from the safety standpoint to reduce head injuries and make them lighter. The baseline comparison study under impact for different foam configurations is compared with a conventional EPS foam sample without corrugation. Corrugated foam designs under current investigation are 12.5–20% lighter and provide up to 10% higher energy absorption. The details of the novel manufacturing concept, CPSC 1203 helmet impact tests, high-speed camera study to understand the differences in the failure mechanisms are deliberated in this paper.

A machine learning approach to estimate the strain energy absorption in expanded polystyrene foams

2021 ◽  
pp. 0021955X2110210
Author(s):  
Alejandro E Rodríguez-Sánchez ◽  
Héctor Plascencia-Mora
Keyword(s):  
Neural Network ◽  
Energy Absorption ◽  
Mechanical Energy ◽  
Compressive Loading ◽  
Ground Truth ◽  
Expanded Polystyrene ◽  
Polystyrene Foam ◽  
Stress Strain ◽  
Ground Truth Data ◽  
Expanded Polystyrene Foam

Traditional modeling of mechanical energy absorption due to compressive loadings in expanded polystyrene foams involves mathematical descriptions that are derived from stress/strain continuum mechanics models. Nevertheless, most of those models are either constrained using the strain as the only variable to work at large deformation regimes and usually neglect important parameters for energy absorption properties such as the material density or the rate of the applying load. This work presents a neural-network-based approach that produces models that are capable to map the compressive stress response and energy absorption parameters of an expanded polystyrene foam by considering its deformation, compressive loading rates, and different densities. The models are trained with ground-truth data obtained in compressive tests. Two methods to select neural network architectures are also presented, one of which is based on a Design of Experiments strategy. The results show that it is possible to obtain a single artificial neural networks model that can abstract stress and energy absorption solution spaces for the conditions studied in the material. Additionally, such a model is compared with a phenomenological model, and the results show than the neural network model outperforms it in terms of prediction capabilities, since errors around 2% of experimental data were obtained. In this sense, it is demonstrated that by following the presented approach is possible to obtain a model capable to reproduce compressive polystyrene foam stress/strain data, and consequently, to simulate its energy absorption parameters.

Effect of polymer foam anisotropy on energy absorption during combined shear-compression loading

2017 ◽  
Vol 54 (3) ◽  
pp. 597-613 ◽  
Author(s):  
Yasmine Mosleh ◽  
Kelly Vanden Bosche ◽  
Bart Depreitere ◽  
Jos Vander Sloten ◽  
Ignaas Verpoest ◽  
...  
Keyword(s):  
Energy Absorption ◽  
Transverse Shear ◽  
Axial Loading ◽  
Expanded Polystyrene ◽  
Polystyrene Foam ◽  
Polymer Foam ◽  
Expanded Polystyrene Foam ◽  
Shear Loads ◽  
Loading Direction ◽  
Compression Behaviour

Polymeric foams are extensively used in applications such as packaging, sports goods and sandwich structures. Since in-service loading conditions are often multi-axial, characterisation of foams under multi-axial loading is essential. In this article, quasi-static combined shear-compression behaviour of isotropic expanded polystyrene foam and anisotropic polyethersulfone foam was studied. For this, a testing apparatus which can apply combined compression and transverse shear loads was developed. The results revealed that the shear and compression energy absorption, yield stress and stiffness of foams are dependent on deformation angle. The total energy absorption of the anisotropic polyethersulfone foam is shown to be direction dependent in contrast to isotropic expanded polystyrene. Furthermore, for similar relative density, polyethersulfone foam absorbs more energy than expanded polystyrene foam, regardless of deformation angle. This study highlights the importance of correct positioning of foam cells in anisotropic foams with respect to loading direction to maximise energy absorption capability.

Numerical analysis of energy absorption in expanded polystyrene foams

2019 ◽  
Vol 56 (4) ◽  
pp. 411-434
Author(s):  
Alejandro E Rodríguez-Sánchez ◽  
Héctor Plascencia-Mora ◽  
Elías R Ledesma-Orozco ◽  
Eduardo Aguilera-Gómez ◽  
Diego A Gómez-Márquez
Keyword(s):  
Finite Element ◽  
Stress Response ◽  
Finite Element Model ◽  
Energy Absorption ◽  
Material Model ◽  
Element Model ◽  
Expanded Polystyrene ◽  
Polystyrene Foam ◽  
Loading Rates ◽  
Expanded Polystyrene Foam

The expanded polystyrene foam is widely used as a protective material in engineering applications where energy absorption is critical for the reduction of harmful dynamic loads. However, to design reliable protective components, it is necessary to predict its nonlinear stress response with a good approximation, which makes it possible to know from the engineering design analysis the amount of energy that a product may absorb. In this work, the hyperfoam constitutive material model was used in a finite element model to approximate the mechanical response of an expanded polystyrene foam of three different densities. Additionally, an experimental procedure was performed to obtain the response of the material at three loading rates. The experimental results show that higher densities at high loading rates allow better energy absorption in the expanded polystyrene. As for the energy dissipation, high dissipation is obtained at higher densities at low loading rates. In the numerical results, the proposed finite element model presented a good performance since root mean square error values below 9% were obtained around the experimental compressive stress/strain curves for all tested material densities. Also, the prediction of energy absorption with the proposed model was around a maximum error of 5% regarding the experimental results. Therefore, the prediction of energy absorption and the compressive stress response of expanded polystyrene foams can be studied using the proposed finite element model in combination with the hyperfoam material model.

scholarly journals FEA and Quasi-static Test on Energy Absorption Characteristic of Space Orthogonal Concave Honeycomb Structure with Negative Poisson’s Ratio

2022 ◽  
Vol 2160 (1) ◽  
pp. 012064
Author(s):  
Nan Sun ◽  
Shuai Wang ◽  
Kaifa Zhou ◽  
Wenyi Ma ◽  
Bohao Xu
Keyword(s):  
Energy Absorption ◽  
Poisson’S Ratio ◽  
Honeycomb Structure ◽  
Absorption Capacity ◽  
Poisson's Ratio ◽  
Absorption Characteristic ◽  
Negative Poisson’S Ratio ◽  
Energy Absorption Capacity ◽  
Static Compression ◽  
Negative Poisson's Ratio

Abstract As a representative of metamaterials, negative Poisson’s ratio (NPR) material possesses special mechanical properties such as expansion, negative compression ratio and so forth. As a result, it is widely used in the fields of vehicles, aerospace, et al. In this paper, a novel space orthogonal concave honeycomb structure (OC) is designed based on traditional concave honeycomb structure (CHS). In order to explore the influence rule of OC structure on the deformation and energy absorption capacity of crash box under low-speed collision, mechanical analysis and parameter research on OC structure are conducted through quasi-static compression test and numerical simulation. The results suggest that the finite element results of OC structure fit well with the experimental results, and the FEM is highly credible. In addition, the novel OC sandwich structure can effectively enhance the deformation capacity and improve the energy absorption performance of the crash box. When the wall thickness ? of OC structure is 1mm and angle ? is 50°, the deformation and energy absorption capacity of the crash box increased by 25.6% and 19.3% respectively.

Theoretical and experimental study of width effects on horizontal flame spread over extruded and expanded polystyrene foam surfaces

2013 ◽  
Vol 32 (3) ◽  
pp. 193-209 ◽  
Author(s):  
Lin Jiang ◽  
Huahua Xiao ◽  
Yang Zhou ◽  
Weiguang An ◽  
Weigang Yan ◽  
...  
Keyword(s):  
Experimental Study ◽  
Flame Spread ◽  
Expanded Polystyrene ◽  
Polystyrene Foam ◽  
Expanded Polystyrene Foam

Cost-Effectiveness Analysis of Bicycle Helmet Subsidies in a Defined Population

PEDIATRICS ◽  
1993 ◽  
Vol 91 (5) ◽  
pp. 902-907
Author(s):  
Robert S. Thompson ◽  
Diane C. Thompson ◽  
Frederick P. Rivara ◽  
Angela A. Salazar
Keyword(s):  
Cost Effectiveness ◽  
Head Injuries ◽  
Puget Sound ◽  
Cost Effectiveness Analysis ◽  
Bicycle Helmet ◽  
Discount Rates ◽  
Health Maintenance ◽  
Helmet Use ◽  
Bicycle Safety ◽  
Effectiveness Analysis

Objective. To examine the potential effects of bicycle safety helmet cost subsidy on bicycle head injury rates and costs. Design. Using empiric data on the incidence and costs of bicycle injuries to children, we examined the hypothetical effects of various bicycle helmet subsidies in a cost-effectiveness analysis. A hypothetical cohort of 100 000 5- through 9-year-olds was followed for 5 years after helmet cost subsidization. Sensitivity analyses were done of three different levels of safety helmet subsidy ($5, $10, $15), three discount rates (2%, 4%, 6%), 10 levels of safety helmet use ranging from 10% to 100%, and the occurrence or nonoccurrence of catastrophic head injuries. Patients. Forty-three children 5 through 9 years of age and 27 children 10 through 14 years of age with head injuries due to bicycling were identified through emergency department surveillance of a population of 29 533. Setting. Group Health Cooperative of Puget Sound, a large health maintenance organization. Outcome measures. Bicycle head injuries prevented and the savings or costs associated with various subsidy, safety helmet use, and discount rates. Results. Hypothetically, an increase in bicycle helmet use rates to 40% to 50% due to subsidies of $5 or $10 prevents 564 to 840 head injuries in a cohort of 100 000 5- through 9-year-olds over 5 years. Under these conditions and a 2% discount rate, cost savings ranging from $189 207 to $427 808 will result when catastrophic head injuries are included in the analysis. Conclusion. Subsidization of bicycle safety helmets to achieve a cost of $14 to $20 per helmet and use rates of 40% to 50% will likely prove cost-effective. Empirical evidence from a Seattle campaign suggests that such helmet use rates are achievable.

Evaluation of a Promotional Strategy to Increase Bicycle Helmet Use by Children

PEDIATRICS ◽  
1993 ◽  
Vol 91 (4) ◽  
pp. 772-777
Author(s):  
Patricia C. Parkin ◽  
Laura J. Spence ◽  
Xiaohan Hu ◽  
Katherine E. Kranz ◽  
Linda G. Shortt ◽  
...  
Keyword(s):  
Low Income ◽  
Head Injuries ◽  
Control Area ◽  
High Income ◽  
Bicycle Helmet ◽  
Helmet Use ◽  
Modest Increase ◽  
Promotional Strategy ◽  
Intervention Area ◽  
Low Income Families

Bicycle-related head injuries are an important cause of death and disability, despite the availability of helmets. The objective of this study was to evaluate the effectiveness of a school-based bicycle helmet promotion program in increasing helmet use by children while controlling for secular trends. Two high-income and two low-income schools in an urban Canadian community were selected to receive a bicycle helmet promotion intervention, with the remaining 18 schools serving as controls. Approximately 1800 observations of bicycling children were made at randomly selected observational sites 2 to 5 months after the intervention to assess changes in behavior. Helmet use at all observation sites tripled from 3.4% (1990, preintervention) to 16% (1991, postintervention). In the high-income intervention area, observed helmet use rose dramatically from 4% to 36% in contrast to the more modest increase in the high-income control area from 4% to 15%. In the low-income intervention area, there was a modest increase from 1% to 7%, but it did not differ from the increase in the low-income control area from 3% to 13%. The program was highly successful in children of high-income families but not in children of low-income families. Developing strategies for low-income families remains a priority.

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