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Beschorner KE, Nasarwanji M, Deschler C, Hemler SL. Prospective validity assessment of a friction prediction model based on tread outsole features of slip-resistant shoes. APPLIED ERGONOMICS 2024; 114:104110. [PMID: 37595332 PMCID: PMC10847959 DOI: 10.1016/j.apergo.2023.104110] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Revised: 07/20/2023] [Accepted: 08/09/2023] [Indexed: 08/20/2023]
Abstract
Shoe outsole design strongly influences slip and fall risk. Certain tread features that can be readily measured have been shown to predict friction performance. This research aimed to replicate those findings and quantify their ability to predict slipping. Participants (n = 34) were exposed to a low friction oil-coated floor surface, while wearing slip-resistant shoes. The coefficient of friction (COF) of each shoe were predicted based on tread surface area, the presence of a bevel, and hardness. The COF was measured, and the slip outcome was determined. Predicted and measured COF were correlated, and measured COF was a sensitive predictor of slip outcome. The relationship of predicted COF on slip outcome was weaker than anticipated and was not statistically significant. This study partially confirmed the ability of previous regression equations to predict COF. However, the effect size was weaker than previously reported and predicted COF was not sensitive for predicting slips.
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Affiliation(s)
- Kurt E Beschorner
- Department of Bioengineering, University of Pittsburgh, 3700 O'Hara St., Pittsburgh, PA, 15213, USA.
| | - Mahiyar Nasarwanji
- Department of Bioengineering, University of Pittsburgh, 3700 O'Hara St., Pittsburgh, PA, 15213, USA
| | - Chris Deschler
- Department of Bioengineering, University of Pittsburgh, 3700 O'Hara St., Pittsburgh, PA, 15213, USA
| | - Sarah L Hemler
- Department of Bioengineering, University of Pittsburgh, 3700 O'Hara St., Pittsburgh, PA, 15213, USA
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2
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Uno T, Mitsui S, Watanabe M, Takiguchi C, Horiuchi M. Different Influencing Factors for Risk of Falls Between Men and Women while Descending from Mount Fuji. Wilderness Environ Med 2023; 34:143-152. [PMID: 36870861 DOI: 10.1016/j.wem.2023.01.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2022] [Revised: 12/26/2022] [Accepted: 01/09/2023] [Indexed: 03/06/2023]
Abstract
INTRODUCTION Annually, approximately 250,000 people climb Mount Fuji in Japan. Nonetheless, only few studies have examined the prevalence of falls and related factors on Mount Fuji. METHODS We conducted a questionnaire survey of 1061 participants (703 men and 358 women) who had climbed Mount Fuji. The following information was collected: age, height, body weight, luggage weight, experience on Mount Fuji, experience on other mountains, presence or absence of a tour guide, single-day climber or overnight-stay lodger, information on the downhill trail (volcanic gravel, long distance, and the risk of falls), presence or absence of trekking poles, shoe type, shoe sole condition, and fatigue feeling. RESULTS The fall rate in women (174/358; 49%) was greater than that in men (246/703; 35%). A prediction model using multiple logistic regression (no fall, 0; fall, 1) indicated that the following factors decreased the risk of falls: male sex, younger age, previous experience on Mount Fuji, having information about long-distance downhill trails, wearing hiking shoes or mountaineering boots rather than other types of shoes (eg, running shoes, sneakers) or worn-out shoes, and not feeling fatigued. Additionally, the following factors may decrease the risk of falls in women only: experience hiking on any other mountains, not being part of a guided tour, and using trekking poles. CONCLUSIONS Women had a higher risk of falls on Mount Fuji than men. Specifically, having less experience on any other mountains, being part of a guided tour, and nonuse of trekking poles may relate to higher risks of falls in women. These results suggest that different precautionary measures for men and women are useful.
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Affiliation(s)
- Tadashi Uno
- Division of Human Environmental Science, Mount Fuji Research Institute, Fuji-yoshida-city, Yamanashi, Japan
| | - Satomi Mitsui
- Division of Human Environmental Science, Mount Fuji Research Institute, Fuji-yoshida-city, Yamanashi, Japan
| | - Misato Watanabe
- Division of Human Environmental Science, Mount Fuji Research Institute, Fuji-yoshida-city, Yamanashi, Japan
| | - Chieko Takiguchi
- Division of Human Environmental Science, Mount Fuji Research Institute, Fuji-yoshida-city, Yamanashi, Japan
| | - Masahiro Horiuchi
- Division of Human Environmental Science, Mount Fuji Research Institute, Fuji-yoshida-city, Yamanashi, Japan; Faculty of Sports and Life Science, National Institute of Fitness and Sports in KANOYA, Kanoya-city, Kagoshima, Japan.
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3
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Jakobsen L, Lysdal FG, Bagehorn T, Kersting UG, Sivebaek IM. The effect of footwear outsole material on slip resistance on dry and contaminated surfaces with geometrically controlled outsoles. ERGONOMICS 2023; 66:322-329. [PMID: 35603991 DOI: 10.1080/00140139.2022.2081364] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Accepted: 05/17/2022] [Indexed: 06/15/2023]
Abstract
Previous studies have compared slip resistance of commercially available footwear, however, often lacking the ability to isolate factors such as material and surface properties, or/and geometry. The aim of this study was to compare slip resistance of geometrically identical shoes with varying outsole materials. Three left Ecco Xpedition III shoes were constructed out of three different outsole materials: polyurethane (PU), thermoplastic polyurethane (TPU) and vulcanised rubber (RU). The shoes were tested for dynamic coefficient of friction (DCOF) on a steel and a tile surface, without contamination and with glycerine and canola oil as contaminants. The shoes were significantly (p < 0.001) different from each other across all surface/contaminant conditions/combinations, with the PU having a significantly 61-125% (p < 0.001) higher DCOF on contaminated surfaces compared to the RU outsole.Practitioner summary: Previous research has suggested the importance of studying individual parameters separately of footwear in relation to slip resistance. In this study, we managed to construct geometrically identical shoes and compare the slip resistance between three different outsole materials. We found that the polyurethane outsole was the least slippery choice of material for this specific footwear model on contaminated surfaces.
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Affiliation(s)
- Lasse Jakobsen
- Department of Mechanical Engineering, Technical University of Denmark, Copenhagen, Denmark
| | - Filip Gertz Lysdal
- Department of Mechanical Engineering, Technical University of Denmark, Copenhagen, Denmark
| | - Timo Bagehorn
- Department of Health Science and Technology, Aalborg University, Aalborg, Denmark
| | - Uwe G Kersting
- Department of Health Science and Technology, Aalborg University, Aalborg, Denmark
- Institute of Biomechanics and Orthopaedics, German Sport University Cologne, Koln, Germany
| | - Ion Marius Sivebaek
- Department of Mechanical Engineering, Technical University of Denmark, Copenhagen, Denmark
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4
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Beschorner KE, Chanda A, Moyer BE, Reasinger A, Griffin SC, Johnston IM. Validating the ability of a portable shoe-floor friction testing device, NextSTEPS, to predict human slips. APPLIED ERGONOMICS 2023; 106:103854. [PMID: 35973317 DOI: 10.1016/j.apergo.2022.103854] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Revised: 06/22/2022] [Accepted: 07/13/2022] [Indexed: 06/15/2023]
Abstract
Measuring shoe-floor friction is critical for assessing the safety of footwear products. Portable devices for measuring coefficient of friction (COF) are needed. This study introduces such a device and evaluates its ability to predict human slip events across shoe designs. A portable device (18 kg) was utilized to measure 66 unique shoe-floor-fluid coefficients of friction (COF). Consistent with the shoes, flooring, and fluid contaminants from the COF tests, participants (n = 66) were unexpectedly exposed to the fluid while walking. Slip predictions were made based on a separate training data set. Slip predictions were made prospectively and using logistic regression analyses. The slip predictions were valid (p < 0.001), 91% sensitive, and 64% specific. The logistic regression fit also revealed that the COF values predicted slip outcomes (p = 0.006). This device is expected to expand the capacity of researchers, product developers, forensic engineers, and safety professionals to prevent slips and enhance human safety.
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Affiliation(s)
- Kurt E Beschorner
- Department of Bioengineering, University of Pittsburgh, University of Pittsburgh, 3700 O'Hara St. #302, Pittsburgh, PA, 15261, USA.
| | - Arnab Chanda
- Centre for Biomedical Engineering, Indian Institute of Technology (IIT) Delhi, Hauz Khas, New Delhi, 110016, India; Department of Biomedical Engineering, All India Institute of Medical Science (AIIMS), Ansari Nagar, New Delhi, 110029, India.
| | - Brian E Moyer
- XRDS Systems, 1334 Luzerne St Ext, Johnstown, PA, 15905, USA.
| | | | - Sarah C Griffin
- Department of Bioengineering, University of Pittsburgh, University of Pittsburgh, 3700 O'Hara St. #302, Pittsburgh, PA, 15261, USA.
| | - Isaiah M Johnston
- Department of Bioengineering, University of Pittsburgh, University of Pittsburgh, 3700 O'Hara St. #302, Pittsburgh, PA, 15261, USA.
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5
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Bharthi R, Sukinik JR, Hemler SL, Beschorner KE. Shoe Tread Wear Occurs Primarily during Early Stance and Precedes the Peak Required Coefficient of Friction. FOOTWEAR SCIENCE 2022; 14:219-228. [PMID: 37583564 PMCID: PMC10427123 DOI: 10.1080/19424280.2022.2124319] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Accepted: 08/26/2022] [Indexed: 10/14/2022]
Abstract
Worn shoes contribute to injuries caused by slip-and-fall accidents. The peak required coefficient of friction (RCOF) has been associated with tread wear rate. However, the temporal relationship between RCOF and shoe wear is unknown. The purpose of this study was to determine whether the contact region at the time of peak RCOF is consistent with the region of shoe wear. The shoe contact region at peak RCOF was imaged by frustrated total internal reflection. Images of worn tread after months of use were captured. The worn tread region was more posterior than the contact region at RCOF and did not correlate with the contact region at the time of RCOF. The contact regions observed during earlier stance (within 83 ms of heel contact) were more consistent with the worn region, suggesting that RCOF may not directly cause tread wear. These results serve to motivate future studies to identify early-stance gait parameters associated with tread wear development.
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Affiliation(s)
- Rosh Bharthi
- Department of Bioengineering, University of Pittsburgh, 301 Schenley Place, 4420 Bayard St., Pittsburgh, PA 15213, United States
| | - Joseph R. Sukinik
- Department of Bioengineering, University of Pittsburgh, 301 Schenley Place, 4420 Bayard St., Pittsburgh, PA 15213, United States
| | - Sarah L. Hemler
- Department of Bioengineering, University of Pittsburgh, 301 Schenley Place, 4420 Bayard St., Pittsburgh, PA 15213, United States
| | - Kurt E. Beschorner
- Department of Bioengineering, University of Pittsburgh, 301 Schenley Place, 4420 Bayard St., Pittsburgh, PA 15213, United States
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6
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The Future of Footwear Friction. PROCEEDINGS OF THE 21ST CONGRESS OF THE INTERNATIONAL ERGONOMICS ASSOCIATION (IEA 2021) 2022. [DOI: 10.1007/978-3-030-74614-8_103] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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7
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Relationship between Friction Coefficient and Surface Roughness of Stone and Ceramic Floors. COATINGS 2021. [DOI: 10.3390/coatings11101254] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Slips and falls are common occupational incidents worldwide. The friction on a floor surface is one of the critical environmental factors affecting the risk of a slip. In this research, we conducted friction measurements on stone and ceramic floor tiles under dry, wet, and water–detergent (WD) solution covered conditions using a horizontal pull slip meter (HPS). Our purposes were to quantify the slip resistance of commonly used stone and ceramic floors under different surface conditions and to validate the curvilinear relationship between the coefficient of friction (COF) and surface roughness of the floors proposed in the literature. The COF data were analyzed together with a surface profile parameter (Ra) of the floor samples. The results showed that the COFs of the stone floors were significantly (p < 0.0001) higher than those of the ceramic floors. All the floors under the dry conditions were slip resistant when adopting the ANSI 1264.2 criterion. Two and five ceramic floors were not slip resistant under the wet and WD solution covered conditions, respectively. Three polynomial regression equations were established to describe the relationship between the COF and Ra. The curvilinear functions of these models indicate that the three-zone (initial growth, steady-growth, and plateau) concept concerning the COF–Ra relationship in the literature was valid when static COF values measured using an HPS were adopted. In addition, the three-zone concept was valid not only on WD solution covered surfaces but also on dry and wet surfaces.
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Roshan Fekr A, Li Y, Gauvin C, Wong G, Cheng W, Fernie G, Dutta T. Evaluation of Winter Footwear: Comparison of Test Methods to Determine Footwear Slip Resistance on Ice Surfaces. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2021; 18:E405. [PMID: 33419196 PMCID: PMC7825554 DOI: 10.3390/ijerph18020405] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Revised: 12/25/2020] [Accepted: 12/29/2020] [Indexed: 11/17/2022]
Abstract
The use of slip-resistant winter footwear is crucial for the prevention of slips and falls on ice and snow. The main objective of this paper is to evaluate a mechanical testing method to determine footwear slip resistance on wet and dry ice surfaces and to compare it with the human-centred test method introduced by researchers at KITE (Knowledge, Innovation, Talent, Everywhere)-Toronto Rehabilitation Institute-University Health Network. Phase 1 of this study assessed the repeatability and reproducibility of the mechanical method by evaluating ten different occupational winter boots using two SATRA Slip resistance testers (STM 603, SATRA Technology Centre, Kettering, UK). One tester is located in Toronto and one in Montreal. These boots were chosen based on the needs of the IRSST (Institut de Recherche Robert-Sauvé en Santé et en Sécurité du Travail, Montréal, Quebec, Canada), who were primarily interested in providing safe winter footwear for police, firefighters and municipal workers. In Phase 2, the results of the human-centred test approach were compared with the mechanical results. In Phase 3, two of these boots with conflicting results from the previous phases were tested using a second human-centred method. In Phase 1, the mechanical testing results obtained in the two labs showed a high linear correlation (>0.94) and good agreement on both ice surfaces; however, they revealed a bias (~0.06) between the two labs on the dry ice condition. The mechanical and human-centred tests (phase 2) were found to be better correlated in the wet ice condition (R = 0.95) compared to the dry ice condition (R = 0.34). Finally, the rating of the footwear slip resistance based on the number of slips counted in phase 3 was consistent with the rating by the human-centred test method (phase 2), but not the mechanical method (phase 1). The findings of this study provide a better understanding of the limitations of the SATRA ice tray for measuring footwear slip resistance and demonstrate that the mechanical method must be further refined to make it more comparable to the human-centred methods to achieve better agreement with real-world performance.
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Affiliation(s)
- Atena Roshan Fekr
- The Kite Research Institute, Toronto Rehabilitation Institute—University Health Network, Toronto, ON M5G 2A2, Canada; (Y.L.); (G.W.); (W.C.); (G.F.); (T.D.)
- Institute of Biomedical Engineering, University of Toronto, Toronto, ON M5S 3G9, Canada
| | - Yue Li
- The Kite Research Institute, Toronto Rehabilitation Institute—University Health Network, Toronto, ON M5G 2A2, Canada; (Y.L.); (G.W.); (W.C.); (G.F.); (T.D.)
| | - Chantal Gauvin
- Mechanical and Physical Risk Prevention Team, IRSST—Institut de Recherche Robert-Sauvé en Santé et en Sécurité du Travail, Montréal, QC H3A 3C2, Canada;
| | - Gordon Wong
- The Kite Research Institute, Toronto Rehabilitation Institute—University Health Network, Toronto, ON M5G 2A2, Canada; (Y.L.); (G.W.); (W.C.); (G.F.); (T.D.)
| | - Wayne Cheng
- The Kite Research Institute, Toronto Rehabilitation Institute—University Health Network, Toronto, ON M5G 2A2, Canada; (Y.L.); (G.W.); (W.C.); (G.F.); (T.D.)
| | - Geoff Fernie
- The Kite Research Institute, Toronto Rehabilitation Institute—University Health Network, Toronto, ON M5G 2A2, Canada; (Y.L.); (G.W.); (W.C.); (G.F.); (T.D.)
- Institute of Biomedical Engineering, University of Toronto, Toronto, ON M5S 3G9, Canada
| | - Tilak Dutta
- The Kite Research Institute, Toronto Rehabilitation Institute—University Health Network, Toronto, ON M5G 2A2, Canada; (Y.L.); (G.W.); (W.C.); (G.F.); (T.D.)
- Institute of Biomedical Engineering, University of Toronto, Toronto, ON M5S 3G9, Canada
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9
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Ismail SI, Nunome H, Tamura Y. Does visual representation of futsal shoes outsole tread groove design resemblance its mechanical traction, dynamic human traction performance, and perceived traction during change of direction and straight sprint tasks? FOOTWEAR SCIENCE 2020. [DOI: 10.1080/19424280.2020.1825534] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- Shariman Ismadi Ismail
- Graduate School of Sports and Health Science, Fukuoka University, Fukuoka, Japan
- Faculty of Sports Science and Recreation, Universiti Teknologi MARA, Shah Alam, Selangor, Malaysia
| | - Hiroyuki Nunome
- Faculty of Sports and Health Science, Fukuoka University, Fukuoka, Japan
| | - Yuji Tamura
- Faculty of Sports and Health Science, Fukuoka University, Fukuoka, Japan
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10
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Beschorner KE, Siegel JL, Hemler SL, Sundaram VH, Chanda A, Iraqi A, Haight JM, Redfern MS. An observational ergonomic tool for assessing the worn condition of slip-resistant shoes. APPLIED ERGONOMICS 2020; 88:103140. [PMID: 32678768 PMCID: PMC7368090 DOI: 10.1016/j.apergo.2020.103140] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2019] [Revised: 03/27/2020] [Accepted: 04/28/2020] [Indexed: 06/11/2023]
Abstract
Worn shoes are known to contribute to slip-and-fall risk, a common cause of workplace injuries. However, guidelines for replacing shoes are not well developed. Recent experiments and lubrication theory suggest that the size of the worn region is an important contributor to the shoe tread's ability to drain fluid and therefore the under-shoe friction. This study evaluated a simple test for comparing the size of the worn region relative to a common object (AAA and AA battery) as a means of determining shoe replacement. This study consisted of three components involving slip-resistant shoes: Experiment #1: a longitudinal, mechanical, accelerated wear experiment; Experiment #2: a longitudinal experiment where the same shoes were tested after each month of worker use; and Experiment #3: a cross-sectional experiment that exposed participants to a slippery condition, while donning their own worn shoes. The COF (Experiments #1 and #2); under-shoe fluid pressure (all experiments); and slip severity (Experiment #3) were compared across outcomes (fail/pass) of the battery tests. Larger fluid pressures, lower coefficient of friction, and more severe slips were observed for shoes that failed the battery tests compared with those passing the tests. This method offers promise for assessing loss in friction and an increase in slip risk for slip-resistant shoes.
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Affiliation(s)
| | | | - Sarah L Hemler
- Department of Bioengineering, University of Pittsburgh, USA
| | - Vani H Sundaram
- Department of Mechanical Engineering and Material Science, University of Pittsburgh, USA; Department of Mechanical Engineering, University of Colorado Boulder, USA
| | - Arnab Chanda
- Department of Bioengineering, University of Pittsburgh, USA; Center for Biomedical Engineering, India Institute of Technology-Delhi, India
| | - Arian Iraqi
- Department of Bioengineering, University of Pittsburgh, USA
| | - Joel M Haight
- Department of Industrial Engineering, University of Pittsburgh, USA
| | - Mark S Redfern
- Department of Bioengineering, University of Pittsburgh, USA
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11
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Sundaram VH, Hemler SL, Chanda A, Haight JM, Redfern MS, Beschorner KE. Worn region size of shoe outsole impacts human slips: Testing a mechanistic model. J Biomech 2020; 105:109797. [PMID: 32423543 PMCID: PMC7362878 DOI: 10.1016/j.jbiomech.2020.109797] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2019] [Revised: 03/11/2020] [Accepted: 04/12/2020] [Indexed: 11/18/2022]
Abstract
Shoe outsole tread wear has been shown to increase slip risk by reducing the tread's ability to channel fluid away from the shoe-floor interface. This study establishes a connection between geometric features of the worn region size and slipping. A mechanistic pathway that describes the relationship between the worn region size and slip risk is assessed. Specifically, it is hypothesized that an increased worn region size leads to an increase in under-shoe fluid pressure, which reduces friction, and subsequently increases slipping. The worn region size, fluid pressure, and slip outcome were recorded for 57 participants, who were exposed to an unexpected slip condition. Shoes were collected from each participant and the available coefficient of friction (ACOF) was measured using a tribometer. A greater shoe worn region size was associated with increased slip occurrence. Specifically, a 1 mm increase in the characteristic length of the worn region (geometric mean of its width and length) was associated with an increase in slip risk of ~10%. Fluid pressure and ACOF results supported the mechanistic model: an increase in worn region size correlated with an increase in peak fluid pressure; peak fluid pressures negatively correlated with ACOF; and increased ACOF correlated with decreased slip risk. This finding supports the use of worn region size as a metric to assess the risk of slipping.
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Affiliation(s)
- Vani H Sundaram
- Department of Mechanical Engineering, University of Colorado, Boulder, United States; Department of Mechanical Engineering, University of Pittsburgh, United States.
| | - Sarah L Hemler
- Department of Bioengineering, University of Pittsburgh, United States.
| | - Arnab Chanda
- Department of Bioengineering, University of Pittsburgh, United States; Centre for Biomedical Engineering, Indian Institute of Technology Delhi, India.
| | - Joel M Haight
- Department of Industrial Engineering, University of Pittsburgh, United States.
| | - Mark S Redfern
- Department of Bioengineering, University of Pittsburgh, United States.
| | - Kurt E Beschorner
- Department of Mechanical Engineering, University of Pittsburgh, United States; Department of Bioengineering, University of Pittsburgh, United States.
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12
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Beschorner KE, Iraqi A, Redfern MS, Moyer BE, Cham R. Influence of averaging time-interval on shoe-floor-contaminant available coefficient of friction measurements. APPLIED ERGONOMICS 2020; 82:102959. [PMID: 31568960 PMCID: PMC6922306 DOI: 10.1016/j.apergo.2019.102959] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Revised: 09/13/2019] [Accepted: 09/19/2019] [Indexed: 05/24/2023]
Abstract
Available coefficient of friction (ACOF) is a common metric of footwear traction performance. ACOF is the ratio of friction to normal force, often averaged over a time-interval. The time-interval needed to achieve repeatable and valid ACOF is unknown. A post-hoc analysis was performed on nine shoe-floor-contaminant combinations to assess the repeatability and bias of data averaged across 4 time-intervals (2 ms, 50 ms, 100 ms, 200 ms) after the target normal force was reached. The ability to predict human slips was assessed for ACOF across these intervals. Differences in repeatability and validity across the four intervals were small. However, statistically significant differences were observed for the shortest compared with the longest interval (lower repeatability yet modestly improved predictive ability). Given the limited impact of time-interval on the results, a shorter interval of 50 ms is recommended to enable testing of smaller floor samples.
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Affiliation(s)
- Kurt E Beschorner
- Department of Bioengineering, University of Pittsburgh, Benedum Engineering Hall #302, 3700 O'Hara St., Pittsburgh, PA, 15261, United States.
| | - Arian Iraqi
- Department of Bioengineering, University of Pittsburgh, Benedum Engineering Hall #302, 3700 O'Hara St., Pittsburgh, PA, 15261, United States.
| | - Mark S Redfern
- Department of Bioengineering, University of Pittsburgh, Benedum Engineering Hall #302, 3700 O'Hara St., Pittsburgh, PA, 15261, United States.
| | - Brian E Moyer
- Crossroads Consulting, LLC, 1334 Luzerne St Ext, Johnstown, PA, 15905, United States; Mechanical Engineering, University of Pittsburgh Johnstown, Johnstown, PA, 15905, United States.
| | - Rakié Cham
- Department of Bioengineering, University of Pittsburgh, Benedum Engineering Hall #302, 3700 O'Hara St., Pittsburgh, PA, 15261, United States; Department of Physical Therapy, University of Pittsburgh, United States; Department of Ophthalmology, University of Pittsburgh, United States.
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13
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Chanda A, Reuter A, Beschorner KE. Vinyl Composite Tile Surrogate for Mechanical Slip Testing. IISE Trans Occup Ergon Hum Factors 2019; 7:132-141. [PMID: 32724872 PMCID: PMC7386451 DOI: 10.1080/24725838.2019.1637381] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/07/2018] [Revised: 06/24/2019] [Accepted: 06/25/2019] [Indexed: 10/26/2022]
Abstract
BACKGROUND Vinyl composite tile (VCT), which is a common flooring in workplaces, is sometimes utilized as the standard floor material for mechanical slip testing experiments. Unfortunately, VCT is a sub-optimal standard test material, since it changes over time and is difficult to manufacture consistently. PURPOSE This study aimed to identify a durable laboratory-grade substitute flooring that could provide traction results that are representative of footwear performance on VCT. METHODS Eight polymer tiles (cast nylon, polyethylene, polycarbonate, acetal, Delrin, PTFE, polypropylene, and nylon) were tested and the available coefficient of friction (ACOF) was measured and compared with that of two VCT designs. First, a screening test was performed to identify good material candidates based on six shoes and two contaminants (water and oil). Two surrogate candidate tiles were then tested across 17 shoes and three contaminant conditions (water, sodium laurel sulfate, and oil). RESULTS Cast nylon tile was found to be the most generalizable VCT surrogate, exhibiting strong correlations with both VCTs for oil contamination. None of candidates were representative of the VCTs for other contaminants. CONCLUSIONS Cast nylon may be a useful alternative for VCT for standard slip testing of footwear in oily conditions.
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Affiliation(s)
- Arnab Chanda
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA 15213
| | - Aiden Reuter
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA 15213
| | - Kurt E. Beschorner
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA 15213
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