Development of new footwear sole surface pattern for prevention of slip-related falls

• Published in: Safety science 2012-04, Vol.50 (4), p.986-994
• Main Authors: Yamaguchi, Takeshi, Umetsu, Tomoki, Ishizuka, Yusuke, Kasuga, Kenichi, Ito, Takayuki, Ishizawa, Satoru, Hokkirigawa, Kazuo
• Format: Article
• Language: English
• Subjects: Biological and medical sciences; Coefficient of friction; Fall; Footwear; Medical sciences; Miscellaneous; Public health. Hygiene; Public health. Hygiene-occupational medicine; Rubber; Slip
• ISSN: 0925-7535; 1879-1042
• DOI: 10.1016/j.ssci.2011.12.017

► A new footwear sole surface pattern was developed to prevent slip-related falls. ► Hybrid rubber block combining rough and smooth surfaces was prepared. ► Friction tests of the rubber blocks were conducted on liquid-contaminated surfaces. ► The hybrid rubber block provides high SCOF and DCOF values. ► The hybrid rubber block maintains sufficiently large contact area at slip initiation and during sliding. In this study, a new rubber surface pattern for a footwear sole was developed to prevent slip-related falls. This pattern shows a high static coefficient of friction (SCOF) and a high dynamic coefficient of friction (DCOF) when sliding against a liquid contaminated surface. A hybrid rubber block, in which a rubber block with a rough surface (Ra=30.4μm) was sandwiched between two rubber blocks with smooth surfaces (Ra=0.98μm), was prepared. The ratio of the rough surface area to the whole rubber block surface area r was 0%, 30%, 50%, 80%, and 100%. The coefficient of friction of the rubber blocks was measured when sliding against a stainless steel plate with Ra of 0.09μm contaminated with a 90% aqueous solution of glycerol. While the SCOF increased with an increase of the rough surface area ratio r, the DCOF during steady-state sliding decreased with an increase of the rough surface area ratio r. The rough surface area ratio of 50% achieved a SCOF value around 0.5 or more and a DCOF value greater than 0.5. Furthermore, the difference in the value of the SCOF and DCOF was the smallest for the rubber block with r of 50%. The results indicated that the rubber block with r of 50% would be applicable to a footwear sole surface pattern to prevent slip and fall accidents on contaminated surfaces.