Additive manufactured textiles for high-performance stab resistant applications

A series of nanocrystalline copper metallised and non-metallised Laser Sintered (LS) Nylon (PA2200) samples using the EOS P100 Formiga system, were stab tested to current Home Office Scientific Development Branch (HOSDB) Knife Resistance (KR) 2007 standards, to ascertain their stab resistant characteristics. The research demonstrated that while a sample thickness of 8mm virgin PA2200 was required for a successful stab test, this figure was significantly reduced to 5.6mm using a 50:50 mix of virgin and recycled PA2200. A further significant reduction in sample thickness to 4.5mm was also recorded for samples manufactured from virgin PA2200, metallised in a 150μm layer of nanocrystalline copper. The results of the stab testing series were then utilised to develop a non-metallised, scale Additive Manufactured (AM) textile manufactured from a 50:50 recycled and virgin PA2200 mix. Results indicated a successful AM textile-like design, with little or no penetration during stab testing at the HOSDB KR1 standard

Utilising Additive Manufacturing technology for the development of knife resistant soft body armour to UK performance requirements

Utilising Additive Manufacturing technology for the development of knife resistant soft body armour to UK performance requirement

Compressive properties of additively manufactured materials compared to foams traditionally used for blunt force trauma protection

The aim of this study is to test currently available additive manufacturing (AM) materials against those used in personal protective clothing (PPC) in sport for blunt force trauma (BFT) protection in sport. Compression was identified as the primary mode of deflection during BFT therefore compression testing was chosen. Compressive stiffness and energy of AM polymers & rubber like materials were compared to those of traditional foam materials. This data will be used demonstrate the difference in behaviour between these materials and those used in AM during compression. Polymer and rubber like materials from three different AM processes were compared to three different foam materials in three different densities. Rubberlike materials absorbed the most energy while polymer samples absorbed very little. Some foam materials absorbed quantities of energy comparable to those absorbed by the rubber-like materials, however, they did so over a greater strain range

The effect of geometry on mechanical properties of biodegradable polylactic-acid tensile-test specimens by material extrusion

Additive manufactured biomedical devices have been widely used in the biomedical fields due to the development of biomaterials and manufacturing techniques. Biodegradable Polylactic Acid-based polymers are the most common material that can be manufactured using material extrusion, one of the most widely known additive manufacturing methods. However, medical grade polymers are too expensive for degradation studies with common tensile specimens. Therefore, this paper aims to reduce the volume of the material used for manufacturing tensile specimen by introducing a new tensile specimen, Micro-X tensile specimen, developed for steel. Young’s Modulus and Ultimate Tensile Strength of micro-X tensile specimens were compared with the ASTM D1708 standard specimens. The experimental results showed that there is no significant difference in terms of mechanical properties. Furthermore, the micro-X tensile specimen was reduced the volume and as well as the cost by approximately 91% in comparison to ASTM D1708 standard tensile specimen

Reconfigurable and transportable container-integrated production system

In this paper, the concept and the prototype realization of a novel reconfigurable small-footprint manufacturing system in a transportable container is presented. The containerized format enables transportation of the system to provide on-site manufacturing, enabling the benefits of localized service delivery without duplication of equipment at multiple locations. Three industrial product use cases with varying manufacturing and performance requirements were analyzed. All of the use cases demanded highly customized products with high quality in low production volumes. Based on their requirements, a general system specification was derived and used to develop a concept for the container-integrated factory. A reconfigurable, modular manufacturing system is integral to the overall container concept. Production equipment was integrated in the form of interchangeable process modules, which can be quickly connected by standard utility supply and control interfaces. A modular and self-configuring control system provides assisted production workflow programming, while a modular process chain combining Additive Manufacturing, milling, precision assembly and cleaning processes has been developed. A prototype of the container-integrated factory with reconfigurable process modules and control system has been established, with full functionality and feasibility of the system demonstrated

Additive manufactured textiles for high-performance stab resistant applications

Purpose – The purpose of this paper is to ascertain the stab resistance characteristics of a series of planar and articulated laser sintered (LS) samples, in accordance with the United Kingdom Home Office Scientific Development Branch (HOSDB) Body Armour Standard – Publication 39/07. Design/methodology/approach – A series of LS planar samples were manufactured using an EOS P100 Formiga system, manufactured from 100 per cent virgin or a 50:50 mix of recycled and virgin Nylon (PA2200), ranging in thickness from 1-10 mm. All planar samples were stab tested to the HOSDB knife-resistance (KR) level one impact energy of 24 Joules, using an in-house manufactured HOSDB guided rail drop test impact rig and standardised knives. Penetration through the underside of each sample was measured and recorded. These results were then used to develop an articulated, additive manufactured (AM) scale textile – LS from a 50:50 mix of recycled and virgin PA2200 powder. These samples were then tested using the aforementioned impact rig and stab impact energy. Findings – The research demonstrated that while virgin PA2200 sample required a minimum thickness of 8mm to achieve stab-resistance below the HOSDB maximum penetration limit of 7 mm, this figure can be reduced to 5.6mm when manufacturing LS planar samples from a 50:50 mix of virgin and recycled PA2200. Results from stab testing the articulated samples indicated a successful AM textile-like design, with a maximum knife penetration of 1.6mm – below the 7mm HOSDB limit. Originality/value – The paper describes a unique application of AM technologies for the manufacture of high-performance stab resistant AM textiles. Keywords Textile technology, Protective clothing, Advanced manufacturing technologies, Laser sintering, High-performance, Stab resistant, Additive manufactured textile, Body armour, Home Office Scientific Development Branch, United Kingdo

Can we reliably and repeatably measure interfacial friction? [Abstract]

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Assessing the stab resistive performance of material extruded body armour specimens

This paper investigates the effect of material extruded body armour specimen size on stab penetration depth and back-face signature (BFS) and establishes the minimum thickness required for a series of material extrusion materials to provide protection against the UK Home Office Scientific Development Branch (HOSDB) body armour KR1-E1 requirements. In stage one, material extruded planar test specimens ranging from 40 × 40 mm to 80 × 80 mm in length and width with 10 mm increments at three different thicknesses, 6, 8 and 10 mm, were stab tested under 24 joules of impact energy using a gravity driven drop test apparatus. In stage two, 50 × 50 mm specimens in six material categories, PC, ABS, PLA, TPLA, PA and TPU, were manufactured at different thicknesses via material extrusion and impacted in accordance with the UK HOSDB KR1-E1 stab impact energy level as they were the optimum size when considering overall stab and BFS performance. The study established the fundamental steps towards the use of material extrusion in future personal protection solutions. Results demonstrated that stab penetration and BFS were dependent on specimen size, thickness and material type, and there was an inverse relationship between stab penetration depth and BFS. Also, a minimum thickness of 5 mm for PC and TPLA, 6 mm for ABS, 7 mm for PLA, 11 mm for PA and 12 mm for TPU, with 100% print density, was required in order to provide protection against the HOSDB KR1-E1 level of 24 J stab impact energy

Body mapping of skin friction coefficient and tactile perceptions during the dynamic skin-textile interaction

The clothing fabric and skin interact continuously across the many regions on users` bodies during wear, which can lead to both physical skin damage and discomfort. Therefore, this investigation aimed to explore the regional differences in skin friction, tactile perception and sensitivity in both females and males during the skin-textile interaction. The static and dynamic friction coefficient and textile perceptions (texture, stickiness, pleasantness, and discomfort) were measured across the 36 selected testing body areas by using a friction measurement device. The results revealed there was a significant difference in skin friction, tactile perceptions, and sensitivity across the various body regions. The anterior neck had the highest skin friction in both females and males, and participants generally rated higher texture perception in their anterior aspects compared to posterior and lateral regions. There was no significant difference in skin friction, tactile perception ratings, and sensitivity between females and males. </p

Assessing the design and compressive performance of material extruded lattice structures

With additive manufacturing increasingly being embraced in the area of sports technology, focus has shifted toward cellular structures for impact protection. Periodic lattice structures can be tailored for a specific response by modifying the geometry of individual cells, with the structure capable of being modified to conform around a given body. However, the effect of modifying specific design characteristics within a lattice and the interrelationships between them are not well understood. This study examines five geometric design variables: cell width, strut cross-sectional area (CSA), strut shape, cell orientation, and joint filleting, and their effect on the compressive behavior of a lattice structure. Truncated octahedron lattices were manufactured using nylon through the process of material extrusion and tested under compression at a constant strain rate of 1.0 s−1. Design of experiments was utilized to analyze the results by implementing a 2(5-1) factorial design. Results indicated that the strut CSA, cell width, and interaction between the two design characteristics had the largest effects on the plateau stress of the lattice and its energy capacity.</div