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Investigation of Stab Protection Properties of Aramid Fibre-Reinforced 3D Printed Elements

100%

Sitotaw D. B. , Ahrendt D. , Kyosev Y. , Kabish A. K.

Fibres & Textiles in Eastern Europe

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2021

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tom Vol. 29, no. 3 (147)

67--73

EN

A stab resistant vest is a reinforced piece of body armour designed to resist knife or needle attacks of different energy levels specifically to the upper part of the body (chest and abdomen) to save lives. The majority of armours limit several comfort parameters, such as free locomotion, respiration, flexibility and light weight, which determine efficient use by wearers and their willingness to wear. Currently available armours are usually made of a single plate, and although often segmentation is used with just a few but still quite large pieces, the materials are compact and bulky to wear. In this study, stab protective armor elements (scale-like elements) of 3 mm thickness and 50 mm diameter were designed, produced (3D printed) and tested for performance. Aramid fibre was used for its strength, durability and process ability to develop protection elements at unidirectional and multidirectional filling angles during 3D printing. The specimens were tested according to VPAM KDIW 2004. The specimens designed and developed with multidirectional filling angles of aramid resist the puncturing energy level K1 (25 J) with a penetration depth less than the maximum allowed for the K1 energy level by VPAM. These specimens showed a high protection level of relative small thickness (3 mm) and light weight (6.57 grams for the estimated area A ≈ 1963.5 mm2) as compared to the currently certified armors for K1 (for example, the aluminum mass is 13.33 grams for 2 mm thickness and 50 mm diameter).

PL

Kamizelka odporna na dźgnięcie to wzmocniony element kamizelki kuloodpornej zaprojektowany tak, aby był odporny na ataki nożem lub igłą, w szczególności w górnej części ciała (klatce piersiowej i brzuchu), tak aby ratować życie. Kamizelka taka powinna spełniać kilka parametrów komfortu, takich jak: swoboda poruszania się, oddychanie, elastyczność i niewielka waga, które decydują o efektywnym użytkowaniu przez użytkowników i ich chęci do noszenia. Obecnie dostępne kamizelki są zwykle wykonane z jednej płyty i chociaż często stosuje się segmentację z zaledwie kilkoma, ale wciąż dość dużymi elementami, materiały są zwarte i nieporęczne w noszeniu. W pracy zaprojektowano, wyprodukowano (wydrukowano w 3D) i przetestowano pod kątem wydajności elementy pancerza ochronnego (elementy przypominające łuski) o grubości 3 mm i średnicy 50 mm. Zastosowano włókno aramidowe ze względu na jego wytrzymałość, trwałość i zdolność do wytwarzania elementów zabezpieczających przy jednokierunkowych i wielokierunkowych kątach wypełnienia podczas druku 3D. Próbki badano zgodnie z VPAM KDIW 2004. Stwierdzono, że zaprojektowane i opracowane próbki były odporne na poziom energii przebicia K1 (25 J) przy głębokości penetracji mniejszej, niż maksymalna dopuszczalna dla poziomu energii K1 przez VPAM. Próbki te wykazały wysoki poziom ochrony przy stosunkowo małej grubości (3 mm) i niewielkiej wadze (6.57 g dla szacowanego obszaru A ≈ 1963.5 mm2) w porównaniu z obecnie certyfikowanymi pancerzami dla K1 (np.: masa aluminium wynosi 13,33 g dla grubości 2 mm i średnicy 50 mm).

2

A Review on the Performance and Comfort of Stab Protection Armor

100%

Sitotaw D. B. , Ahrendt D. , Kyosev Y. , Kabish A. K.

Autex Research Journal

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2022

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tom Vol. 22, no. 1

96--107

EN

Stab-protective clothing is the most important component of safety equipment and it helps to save the lives of its wearers; therefore, it is designed to resist knife, nail, or needle attacks, especially to the upper body. In this paper, the essential requirements for stab-resistant armor are investigated based on an in-depth review of previous research and prototype test results. The combination of protection and comfort in armor vests is a particularly challenging task. Review of the state of the art technology responsible for the manufacture of stab-resistant clothes has revealed that their design and development should encompass the elements of comfort, freedom of movement, permeability, absorption, evaporation, and weight reductions to ensure excellent ergonomics and high wear comfort. The design as well as the production, weight, thickness, material types and properties, and the arrangement of scales determine the level of protection and comfort offered by stab-resistant vests. Currently, the production of stab-proof gear-based 3D printing technology is evaluated, using lightweight materials (aramid) in the form of segmented scales inspired by nature. As the protection performance and wear comfort of stab-proof gear is enhanced, the willingness of security, control, transport, custom, and correction officers to wear them can be significantly increased in an endeavor to ensure that fatal injuries will decrease significantly.

3

Numerical Investigation of the Air Gap Distribution of Jackets with Different Fits and its Influence on Human Temperature

100%

Awais M. , Krzywinski S. , Kyosev Y.

Fibres & Textiles in Eastern Europe

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2021

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tom Vol. 29, no. 6 (150)

77--86

EN

The air gaps underneath clothing have a great influence on the thermal regulation of the human body. The distribution of the air gaps depends on the shape of the human body as well as on clothing style, fit, and deformation properties. This paper reports on the influence of clothing fit on thermophysiological parameters of the human body through thermal simulation. Four different fits of jacket and a test person were considered for the investigation and for simulation purposes. The results of the simulation concluded that different thermal regulations of the human body were exhibited for different fits of the jacket, which is due to distinct air gaps between the human body and clothing for each fit of the jacket. This research work presents a fast method to predict the influence of clothing fit on thermal comfort, which is usually studied by a time-consuming, laborious method – the wear trial.

4

Conductive Heat Transfer Prediction of Plain Socks in Wet State

75%

Mansoor T. , Hes L. , Khalil A. , Militky J. , Tunak M. , Bajzik V. , Kyosev Y.

Autex Research Journal

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2022

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tom Vol. 22, no. 4

391--403

EN

In this study, an algebraic model and its experimental verification was carried out to investigate the effect of moisture content on the heat loss that takes place due to conduction of sock fabrics. The results show that increasing moisture content in the studied socks caused a significant increase in their conductive heat loss. Plain knitted socks with different fiber composition were wetted to a saturated level, and then their moisture content was reduced stepwise. When achieving the required moisture content, the socks samples were characterized by the Alambeta testing instrument for heat transfer. Three different existing modified mathematical models for the thermal conductivity of wet fabrics were used for predicting thermal resistance of socks under wet conditions. The results from both ways are in very good agreement for all the socks at a 95% confidence level. In the above-mentioned models, the prediction of thermal resistance presents newly a combined effect of the real filling coefficient and thermal conductivity of the so-called “wet” polymers instead of dry polymers. With these modifications, the used models predicted the thermal resistance at different moisture levels. Predicted thermal resistance is converted into heat transfer (due to conduction) with a significantly high coefficient of correlation.