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Dynamic coefficient of friction data for both sock materials, plotted against one another for comparison.
Source publication
In a pursuit to further improve the understanding of the factors influencing friction blister formation, friction between running sock textiles and the skin at the first metatarsal head (1MTH) region was investigated in three different moisture conditions (dry, low moisture and wet).
Context in source publication
Context 1
... sliding friction force data for both sock materials was converted to dynamic coefficients of friction (DCOF) by dividing by the 100 N normal load, on which the data was based. This data is plotted in Figure 3, with each moisture condition indicated. As in Figure 1, the effect of moisture on increasing friction can be seen but a line of gradient 1 allows comparison between socks. ...
Similar publications
Two different methodologies for assessing the friction between plantar skin and sock textiles are compared in this study. The first approach uses a custom-built friction plate rig. The rig consists of sock material mounted on a test plate attached to two load cells that measure normal and shear loads at the skin-sock textile interface. With this me...
Citations
... Friction blisters are frequently occurring painful injuries, common to the foot, that affect everyone from athletes and military personnel to any active individual. Friction blisters are debilitating and can often lead to significant lifestyle changes to reduce or cope with pain [1][2][3][4][5][6][7][8][9]. For athletes such as marathon runner's, friction blisters incidence during any given race can be between 0.2-39% and the pain from these friction blisters could have an adverse effect on their performance [1]. ...
... In the past, researchers have used a variety of different methods to characterize frictional force causing blister formation. Some studies have modified other friction measurement instruments to characterize fabric friction [2][3][4][5]. One study created a "custom built" frictional measuring device [6], while other studies have focused on field investigations where friction blister occurrence is analyzed and indirectly related back to frictional force [13,14]. ...
Background
The purpose of this parametric design of experiments was to identify and summarize how the influence of knit structure (single jersey vs. terry), fiber composition (polyester vs. cotton), fiber linear density (30/1 Ne vs. 18/1 Ne & 1/150/34 vs. 2/150/34), and yarn type (filament vs. spun) affected the frictional profile across the sock-skin interface.
Methods
Friction testing trials were completed against both a polypropylene probe and a synthetic skin material (Lorica soft®) to determine if there was a difference in friction based on interface interaction. Friction testing was completed by sliding a probe across the inside bottom surface of the sock (the part that is usually in-contact with the bottom of the foot) while instantaneously measuring the frictional force every tenth of a second.
Results
For both trials (plastic probe and synthetic skin), in the dry condition, knit structure was found to be the most prominent fabric parameter affecting the frictional force experienced at the sock-skin interface. It was also determined that fiber linear density, and yarn type are tertiary factors affecting the frictional force measured at the sock-skin interface. Finally, in the dry state, it was determined that fiber composition had seemingly no effect on the frictional force experienced at the sock-skin interface.
Conclusion
This parametric design of experiments has further enhanced the understanding of the tribology at the sock-skin interface. Through strategic design, four different textile parameters have been investigated, measured, and justified as to how each influence the friction measured between the two interfaces. This knowledge can be used to develop socks that mitigate the risk of friction blisters formation.
... The frictional properties of textiles can become an important issue when it expedites the development of skin injuries. For example, excessive and repetitive friction from moist textiles (due to absorption of skin sweat) were reported to expedite tissue deformation and skin damage, friction blisters, pressure ulcers (also known as decubitus ulcers), and even more severe unwanted problems in athletes, military, and in people with compromised skin conditions and immobility [1][2][3][4][5][6][7][8][9][10][11]. Therefore, to optimize the fabric frictional properties, depending on applications, it is essential to have an understanding of the structural characteristics of the fibers, yarns and fabrics, and their effects on respective physical and mechanical properties in different micro-climatic conditions. ...
Textiles, next to skin, are an integral part of our lives, govern the skin microclimate, and contribute to our comfort and health. Over the years, natural and synthetic textiles have dominated the industry in diverse application areas. However, when it comes to the sustainability of the raw materials or products, processes, and the environment, the natural polymers or fibers will always dominate the preference. One of the many natural fibers, cotton fiber is the most popular and widely used one, leading to many fundamental researches in the fields of polymers, fibers, fabrics, their manufacturing processes and finishing, as well as in product characterizations and performance evaluations. To-date, most textile-characterization techniques involve processes which compromise the morphology of the textiles being tested, and are mostly destructive. In this chapter, a few novel non-destructive characterizations of textiles, made from natural fibers (specifically cotton), will be discussed which involve X-ray micro-computed tomographic (XRM-CT) three-dimensional (3D) image analysis. Tomographic characterizations allow the investigation of both the surface profiles and the inner construction of the textiles without compromising the morphology. The findings discussed in this chapter will assist in non-destructive characterizations and performance evaluations of other diverse material classes as well.
... Since socks have been shown to be effective in reducing shear forces [26], the addition of the cushioning can help protect zones with sustained excess pressure, and may prevent fatigue associated with long walks or during physical activity. Thus, the use of socks adapted to the needs, discomfort, or pre-existing pathologies can prevent the appearance of such skin lesions as blisters or hyperkeratosis, which are generally caused by high pressure or friction coinciding with a bony prominence [27,28]. ...
Cushioning for the central and plantar zone of the forefoot, integrated into the body of the sock, could reduce excess pressures in that zone. The objective of this study was to verify the capacity of a sock with a cushioning element to reduce forefoot plantar pressures relative to the same sock model without that element. Dynamic plantar pressures were measured in a sample of 38 participants (25 women and 13 men) using the FootScan plate system following the two-step protocol. Measurements were made in three situations selected at random – barefoot, wearing control socks, and wearing the experimental cushioned socks. Maximum pressures were analysed in seven zones of the forefoot (hallux, lesser toes, and 1st to 5th metatarsal heads). The zone of greatest plantar pressure was in all situations located under the 3rd metatarsal head. The pressure was lower (p = 0.009) under the 2nd metatarsal head with the experimental sock (10.2 ± 3.1 N/cm²) than with the other two conditions – barefoot (11.8 ± 3.7 N/cm²) and control sock (11.9 ± 4.9 N/cm²). The 3rd metatarsal head presented lower plantar pressures (p = 0.004) with the experimental sock (12.6 ± 3.8 N/cm²) than barefoot (14.5 ± 4.9 N/cm²). The experimental socks, with plantar cushioning, were able to effectively reduce the plantar pressures on the central part of the forefoot. This reduction may lead to less discomfort for subjects suffering pain in this area, It may also result in avoiding the appearance of possible skin lesions associated with excess pressure (such as calluses, corns, or blisters).
... Bislang gibt es aber nur wenige Hersteller, die der seriellen Einlegesohle eine angemessene funktionelle Bedeutung sowohl im Hinblick auf den mechanischen und thermischen Komfort als auch im Zusammenhang mit der Prävention von Blasenentstehung und der Schuhhygiene beimessen. Dies scheint allerdings nur unter Berücksichtigung der komplexen Interaktion zwischen Einlegesohle, Schaft und Laufsocke möglich zu sein [8,25]. ...
Sportorthopädie Sportorthopädie Seit der Einführung der ersten in-dustriell gefertigten Laufschuhe vor etwa 150 Jahren haben sich die drei primären funktionellen Anforderun-gen nicht verändert: Bei der Konzep-tion von Laufschuhen stehen nach wie vor Verletzungsprävention, Leis-tungsverbesserung und/oder Op-timierung des Komforts im Mittel-punkt. Ebenso wenig haben sich die Hauptbestandteile und somit der prinzipielle Aufbau eines Laufschuhs verändert. Dieser setzt sich aus zwei wesentlichen Komponenten zusam-men: dem Schaft und der Bodenein-heit, die aus Zwischensohle und Au-ßensohle besteht. Dennoch hat der Laufschuh nicht nur sein Aussehen gravierend verändert-auch seine Einsatzgebiete sind vielfältiger ge-worden, was wiederum in der Aus-prägung seiner funktionellen Eigen-schaften deutlich erkennbar ist. Der Artikel stellt neben aktuellen Lauf-schuhtrends auch neueste Material-entwicklungen und damit verbun-dene moderne Fertigungstechnolo-gien vor, deren Anwendung in der Orthopädie-Technik als sinnvoll er-achtet wird. Schlüsselwörter: Laufschuhe, Funkti-on, Konstruktion, Konzepte, Trends Since the introduction of the first industrially manufactured running shoe about 150 years ago, the three main functional requirements have remained the same: Preventing injuries , enhancing performance and/ or optimising comfort are the major goals when designing running footwear. The principle components and hence the structure of a running shoe have also changed very little. A running shoe consist of two main components, the upper and the bottom part, which consists of a midsole and an outsole. Nevertheless, not only has the appearance of running shoes changed considerably, they are now much more versatile, which their functional characteristics make clearly apparent. This article presents current trends in running footwear as well as the latest developments in materials and manufacturing that should be considered for possible application in orthopaedic technology.
... Skin health critically depends on its interaction with fabrics next to skin while excessive friction can expedite the development of friction related skin injuries such as tissue deformation and skin damage, friction blisters (Baussan et al., 2013;Carre et al., 2016;Dong et al., 2015;Duan et al., 2005b;Nuruzzaman et al., 2011;Rao et al., 2009;Tasron et al., 2015;Tasron et al., 2016;Zeng et al., 2006) decubitus ulcers or pressure ulcers (Bader and Bouten, 2005;Basal and Ilgaz, 2009;Derler et al., 2014;Rotaru et al., 2013;Schwartz et al., 2018;Vilhena and Ramalho, 2016;Vadivu, 2015;Zhong et al., 2008), failure of skin graft surgery (Whale et al., 2018) and even more severe unwanted problems. In regard to decubitus, it is also known as pressure ulcers and a severe medical problem especially for immobile patients in clinical environments and nursing homes . ...
Frictional characteristics of textiles play a big role in skin comfort and health, and in the development of friction related skin injuries such as tissue deformation, skin damage, decubitus ulcers or pressure ulcers and friction blisters, especially in people with compromised skin conditions and/or immobility. All these skin injuries cause severe pain and can be life threatening. This review paper is focused on decubitus, and how friction from textiles contribute to both skin comfort, and in the formation or prevention of skin injuries such as decubitus. More than 2.5 million individuals develop decubitus annually that costs the US healthcare system $9.1-11.6 billion per year due to increased health care utilization. There’s been a significant amount of research on decubitus alone, unfortunately the role of textiles in formation and prevention of decubitus is yet understudied. This review provided an understanding of the importance of friction in textiles and skin, and factors influencing friction on respective surfaces. Along with demonstrating the mechanism of decubitus ulcer formation and some recent commendable work from textiles point of view, few critical research questions and suggestions for future work have also been provided.
... Gwosdow et al. [3] found that increasing skin wetness is associated with higher fabric-skin friction and subjective displeasure sensation. If the contact pressure and shear force are high or last for prolonged period, it will cause skin irritations, abrasions or other skin injuries [5], for example decubitus [6,7] or friction blisters [8][9][10]. ...
Increasing skin wetness tends to increase fabric–skin adhesion and friction, resulting in wear discomfort or skin injuries. Here, the magnitude estimation approach was used to assess the stickiness sensation perceived in fabrics. Seven fabric types were wetted by putting onto wet ‘skin’ surface and dried for different durations to achieve different wetness levels, simulating wearing conditions during the recovery period after sweating. Results showed that the relationship between magnitude estimates of stickiness and amount of water present in fabric demonstrated a power function. The exponents and constant from power regression show the growth rate of stickiness sensation with moisture intensity and the perceived stickiness under fixed stimulus intensity, respectively. A novel parameter, accumulated stickiness magnitude (ASM), describing how much discomfort a wetted fabric offered throughout the drying period, was developed. Thin cotton fabrics (fabric W01 and W03), having higher saturation level after contacting with wetted skin surface, arouse stronger stickiness feeling and their ASM is remarkably higher. The difference in stickiness estimates is due to the difference in chemical composition and surface geometry. This study suggests us the way to predict perceived stickiness in fabrics with different wetness levels which is useful for applications like sportswear, intimate apparel or healthcare products.
... In this study, all tests reported were carried out with the socks in a dry condition. The effects of moisture in the sock and skin-sock interface were investigated in an additional study [12]. ...
... In order to effectively isolate the 1MTH, participants were instructed to lift their toes throughout sliding (see Fig 1a). A friction test protocol was adapted from previous studies [1, 11, 12] whereby seated participants press their IMTH region against the test plate and then push their foot forwards across the sock surface, maintaining the initial level of normal load and a relatively consistent, self-monitored, sliding velocity. This process was repeated for a range of applied normal loads. ...
... In order to generate force values that relate to the dynamic coefficient of friction, a stable, central region of normal and shear (friction) force data is selected in the phase (II) region and averages are taken. This protocol has been refined in previous studies and found to give good results [1, 11, 12]Fig. 2bthe force data from Study B is shown plotted against the order of data point collected and can be divided into five different phases. ...
Two different methodologies for assessing the friction between plantar skin and sock textiles are compared in this study. The first approach uses a custom-built friction plate rig. The rig consists of sock material mounted on a test plate attached to two load cells that measure normal and shear loads at the skin-sock textile interface. With this methodology, participants are required to slide their foot over the test plate whilst maintaining a targeted normal load and a relatively consistent sliding speed. The second approach uses a pneumatically-driven foot probe loading device. The device includes an instrumented probe with sock material on its contact surface. Participants are instructed to stand on a platform whilst the probe is applied to, and then driven across, the plantar aspect of foot. The cyclic motion of the probe is displacement-controlled and normal and shear loads are measured using load cells. Both approaches allow friction coefficients to be calculated from load data collected during the sliding phase of movement. Data from both approaches was examined, collected from friction tests using the same six participants and sliding contact between the first metatarsal head (1MTH) region and textiles from two commercially available running socks. Both approaches were capable of measuring the friction between 1MTH skin and sock materials and good agreement was found between them. In the dry conditions tested, the cotton-rich sock was found to provide lower friction that the anti-blister sock material.
This paper presents a multi-response optimization technique to study the effect of linear density and fiber blend (%) on the chafe resistance of knitted fabric. As underwear fabrics come in direct contact with the skin, they demand better chafe resistance properties that depend on the frictional behavior of the garments. The objective of this study is to investigate the effect of different blends (%) of cotton, Coolmax, and micro polyester fibers, as well as two linear densities, i.e., 24/1s and 30/1s (Ne), on the friction and comfort properties of knitted underwear. The yarns’ frictional coefficient and tensile strength were tested. Thermo-physiological and tactile/hand properties of the knitted fabric were also investigated. It was concluded that both factors, blend % and yarn linear density, influenced fabric comfort properties. Combination of natural and synthetics fibers with finer linear density results in better-performing fabrics with regard to friction and moisture management. The statistical tool, analysis of variance, was used to evaluate the significance of the results. Grey relational analysis (GRA) was performed for the optimization of parameters and the sorting of the samples having the best-required properties. The sample containing 50 % cotton and 50 % micro polyester with a 30/1s yarn count was declared as the best sample based on the GRA.
The purpose of this parametric design of experiments was to identify and summarize how the influence of knit structure (single jersey vs. terry), fiber composition (polyester vs. cotton), fiber linear density (30/1 Ne vs. 18/1 Ne & 1/150/34 vs. 2/150/34), and yarn type (filament vs. spun) affected the frictional profile across the sock-skin interface, and then relate these factors to friction blister incidence. Friction testing trials were completed against both a polypropylene probe and a synthetic skin material (Lorica soft ® ) to determine if there was a difference in friction based on interface interaction. Friction testing was completed by sliding a probe across the inside bottom surface of the sock (the part that is usually in-contact with the bottom of the foot) while instantaneously measuring the frictional force every tenth of a second. For both trials (plastic probe and synthetic skin), in the dry condition, knit structure was found to be the most prominate fabric parameter affecting the frictional force experienced at the sock-skin interface. It was also determined that fiber linear density, and yarn type are tertiary factors affecting the frictional force measured at the sock-skin interface. Finally, in the dry state, it was determined that fiber composition had seemingly no effect on the frictional force experienced at the sock-skin interface.
In different mechanical conditions, repetitive friction in combination with pressure, shear, temperature, and moisture leads to skin discomfort and imposes the risks of developing skin injuries such as blisters and pressure ulcers, frequently reported in athletes, military personnel, and in people with compromised skin conditions and/or immobility. Textiles next to skin govern the skin microclimate, have the potential to influence the mechanical contact with skin, and contribute to skin comfort and health. The adhesion−friction theory suggests that contact area is a critical factor to influence adhesion, and therefore, friction force. Friction being a surface phenomenon, most of the studies concentrated on the surface profile or topographic analysis of textiles. This study investigated both the surface profiles and the inner construction of the fabrics through X-ray microcomputed tomographic three-dimensional image analysis. A novel nondestructive method to evaluate yarn and fabric structural details quantitatively and calculate contact area (in fiber area %) experimentally has been reported in this paper. Plain and satin-woven fabrics with different thread densities and made from 100% cotton ring-spun yarns with two different linear densities (40 and 60 Ne) were investigated in this study. The measurements from the tomographic images (pixel size: 1.13 μm) and the fiber area % analysis were in good agreement to comprehend and compare the yarn and fabric properties reported. The fiber area % as reported in this paper can be used to evaluate the skin-textile interfaces and quantitatively determine the contact area under different physical, mechanical, and microclimatic conditions to understand the actual skin-textile interaction during any physical activity or sports. The proposed method can be helpful in engineering textiles to enhance skin comfort and prevent injuries, such as blisters and pressure ulcers, in diversified application areas, including but not limited to, sports and healthcare apparel, military apparel, and firefighter's protective clothing. In addition, the images were capable of precisely evaluating yarn diameters, crimp %, and packing factor as well as fabric thickness, volumetric densities, and cover factors as compared with those obtained from theoretical evaluation and existing classical test methods. All these findings suggest that the proposed new method can reliably be used to quantify the yarn and fabric characteristics, compare their functionality, and understand the structural impacts in an objective and nondestructive way.
