Key Engineering Materials Vol. 800

Abstract: The effect of surface topography in combination with chemical composition on hydrophobicity and static coefficient-of-friction between steel and ice was studied. Polished stainless steel blocks were etched to introduce a roughness, and further treated with octadecanethiol. Carbon rich inclusions, identified by energy-dispersive X-ray spectroscopy, and scratches acted as the exposure centers to promote etching. Due to heterogeneities in steel, rounded cavities and parallel troughs were found on the surface after etching. Etched blocks with a lowered surface energy were studied under various ambient conditions to determine the influence of ice temperature and humidity on the static coefficient-of-friction. Blocks modified with octadecanethiol showed improved hydrophobicity. Warmer ice conditions led to a lower friction, regardless of the surface modification.

Abstract: Many studies use an inclined ice plane to determine the effect of different materials and processing conditions on sliding over an ice surface. Experiments measure the sliding time at different stages on the track to determine the sliding speed and the coefficient-of-friction. Here, the sliding body vibrations and, the oscillations in axial directions are addressed. This paper analyzes the sample’s acceleration by attaching a portable High Sensitivity 1.25g USB Accelerometer and compares the data with 3D CAM modeling results to identify the causes for interrupted sliding.

Abstract: Scientists and sport athletes are constantly seeking for the methods which could improve surface sliding ability on ice. Modifications of contact area and surface roughness are relatively easy but not yet fully understood methods for sliding ability improvements. This research contains information of how one can perform on-field experiments with skeleton sleigh to determine the influence of surface contact area and roughness on sliding ability. Two types of surface roughness i.e. polished (3000 grain sandpaper) and scratched (600 grain sandpaper) are compared using three different contact areas. Obtained data showed that rougher surfaces tend to slide faster if contact area is larger but the effect reverses if contact area is reduced.

Abstract: Winter forces people to adapt to snow and ice conditions and understand the regularities in nature in the cold regions. The understanding of ice and snow regularities can help to improve the safety of moving over ice. The objective of this work was to investigate the impact of ice texture on the static coefficient of friction for stainless steel samples with different surface roughness under laboratory conditions. The ice was prepared flatted, scratched and glazed to represent the various ice textures which might appear in real-life situations. The samples were prepared as rectangular stainless steel blocks with different surface roughness. Contact area between the sample and the ice was considered as the most influential factor. A larger contact area resulted in a higher static coefficient of friction. This outcome provides useful information for working in surroundings with ice.

Abstract: Assuring the comfort of the human body is one of the most important functions of sportswear and leisure wear. Knitted fabrics should have high air permeability for easily transmit of the perspiration from the skin to the atmosphere as well as to feature with good hand thus making the wearer to feel comfortable. In this research, both hand and air permeability of eight commercially available polyester knitted fabrics and their adhesive bonds were investigated. There was shown that textile structure and adhesive bonds make the significant influence on textile hand and permeability to air making them being worse.

Abstract: In order to improve the tactile perception, as well as other comfort properties of modern smart clothing, conventional electrical wires, which are used to connect integrated electronic components, are more and more often replaced by conductive threads. Conductive threads can be used to replace mounting wires in smart clothing, as well as to make sensors. In order to determine the durability of conductive threads made by different manufacturers, a study was conducted in which the conductive threads, which were integrated using embroidery technique, were subjected to multiple washing cycles. After each washing cycle electrical resistance of connections, made by these threads, was measured and its changes were compared. Suggestions about the use of different conductive threads can be found in the conclusions section of this study.

Abstract: Manual therapy is used to treat patients with neck pain, and mobilization techniques are practiced clinically by physiotherapists. To evaluate the effectiveness of therapy it is necessary to measure the applied manual therapy forces. We present the sensitive glove concept designed to measure the forces applied during therapy. The sensitive glove is equipped with multiple textile-based sensors connected by sewing technology, in which changes in electrical resistance were observed due to the applied force. The number and position of sensors were defined basing on the experience of manual therapists and practicable techniques. Glove fabrication technologies were tested practically – sensors were glued and sewn on the base material and simple conductive threads were sewn by hand and with a sewing machine. Technological solutions were evaluated both in terms of visual and technical aspects. The final version of the sensitive glove was assessed by an expert and recommendations were given for improving further prototypes.

Abstract: The functionality of textiles can be complimented by using a wide variety of modification technologies. This study focuses on textile modification with sol-gel technology as a part of smart sock prototype development. Zinc acetate dehydrate (ZAD) is integrated in sol synthesis and used as modifier thus improving modified cotton yarn mechanical properties and also can prolong time between washing, taking into account modifiers antimicrobial properties. Four hanks of pure cotton yarns with length of 300 m, where modified with silica-based sol with 7,5 wt% ZAD as a modifier. As a part of this study tensile strength and elongation of yarn was determined and changes in liner density were observed. Average yarn linear density increases by 19 % and linear density for knitted samples increases by 2,6 %. Therefore, yarn strength for 80 % of modified samples shows mean value of 2,32 N, that is 17 % higher than unmodified samples.

Abstract: Depending on the type of garment to be designed, designers, developers, and retailers are aware of and put forward certain requirements for the implementation of an appropriate level of quality. But ultimately the consumer is the one who decides whether the product meets his individual requirements. There are many different standardized textile testing methods, as well as various subjective assessment methods for hand feel and wearing comfort occurs. The observations that the analysis of a product has to be complex has become increasingly widespread. The aim of the research is to formalize and practically use the conceptual method of drape, appearance and comfort measurements.