Spacer Fabrics Research Articles

Force attenuation capacity of weft-knitted spacer fabric in low-velocity impact

PurposeThis study aimed to determine the peak impact force and force attenuation capacity of weft-knitted spacer fabrics intended for padding that can be used for human body protection against impact.Design/methodology/approachA total of five weft-knitted spacer fabrics were fabricated with four different diameters of nylon monofilament yarns and one doubled monofilament yarns, respectively. The impact performances of the weft-knitted spacer fabrics were tested using a drop test method with a customized test rig to simulate falling. Impact tests were conducted on single- and multilayered experimental spacer fabrics to investigate the peak impact force and force attenuation capacity.FindingsIt was found that weft-knitted spacer fabric with a coarser or larger diameter of monofilament spacer yarn generated lower impact force and higher force attenuation capacity, thus resulting in better impact performance. Greater force attenuation can be achieved by utilizing a higher number of spacer fabric layers. However, the increase in thickness must be considered with the spacer fabric end use.Originality/valueThis study employed relatively coarse nylon monofilament yarn as spacer yarns to gain knowledge on the impact performance of weft-knitted spacer fabrics compared to warp-knitted spacer fabrics which are more common. The results showed that the diameter of spacer yarn significantly influenced the impact performance of the experimental weft-knitted spacer fabrics. These results could be useful for designing and engineering textile-based impact protectors.

Flexible all-textile dual tactile-tension sensors for monitoring athletic motion during taekwondo

Abstract A smart garment as a “second skin,” is the goal to achieve a similar level of multiple stimuli as the quantified sensitivity of skin, and most emerging electronic textiles (E-textiles) simply combined discrete sensors with single function to recognize multiple stimuli. However, such strategy usually leads to complicated stitching E-textiles and unsatisfied wear experience, especially under large strain and pressure deformations. Herein, we propose “all in one” E-textile with a dual tactile and tension stimulus response. This dual response is facilely enabled by a composite textile assembly with core-sheath yarn and spacer fabric. A significant challenge that limits this dual-sensing technology is the so-called “double solution phenomenon” that occurs when the core-sheath yarn demonstrates nonmonotone response along stretching deformation. We solve this challenge by coating the yarns with an insulating polyurethane layer prior to twisting. It is demonstrated that our E-textile exhibits a wide deformation range (up to 90%), a wide pressure detection range (up to 110 kPa), good durability (~100,000 cycles), good hand washability, water vapour permeability, and air breathability. Our fabric-based sensing technology allows for precise monitoring of athletic movement and form, illustrating its potential application in Taekwondo and robust physical training analysis.

Preparation and mechanical properties characterization: plasma‐modified expanded vermiculite/fabric‐reinforced foam composite materials

AbstractExpanded vermiculite (EV) powder was treated with a plasma, and the organic material polyurethane (PU) was combined with the inorganic material EV powder and fabric by means of particle reinforcement and surface reinforcement to prepare a PU cushioning composite material. EV was processed with plasma treatment beforehand. The resulting PU foam cushioning composites were evaluated for static compression performance and dynamic buffering performance, thereby examining the influences of plasma treatment time and fabric type. According to the correlation between the structure and compression performance, the presence of EV provides more nucleation sites during the foaming, which in turn increases the cell density and the compression performance of the PU cushioning composites. In particular, after plasma treatment of 800‐mesh EV for 20 and 30 min, the resulting composite foam had reduced cell diameter and increased density, and enhanced mechanical properties. Besides, in terms of surface reinforcement, covering the surface with fabric will make the foam enter the densification stage in advance, and its compression performance will be enhanced. As for the dynamic cushioning test, the surface‐covering fabric can increase the impact performance, and the foam cushioning material covered with double‐sided fabric is better. Specifically, PU foam covered with warp‐knitted spacer fabric on both sides exhibits a maximal dynamic compression performance as the impact load is attenuated to 5941 N, suggesting an energy absorption of 96.20%. © 2021 Society of Chemical Industry

Low-Velocity Impact Properties of Polyurethane Composites Reinforced with Warp-Knit Spacer Fabric

Eight kinds of polyurethane (PU)-matrix composite samples were prepared by impregnating the warp-knit spacer fabrics with flexible PU foam. An impact test was carried out to investigate the influence of fabric structure parameters on the compression behaviors and energy-absorption efficiency of the composites. By using finite element (FE) analysis and ANSYS software, the unit cell models of the composites were built to simulate the impact responses and get strain-stress curves. Comparison of FE simulation and experimental curves showed good consistency between them.

Impact of seam on liquid transmission behaviour of multi-layered ensembles using sweat and water

Present study is focussed on the effect of seam on the moisture transmission in liquid form. Behaviour of actual sweat is found to be different from pure water used while evaluating the performance of multilayer clothing systems in seamed and unseamed condition in terms of their in-plane (wetting time) & cross-plane moisture transmission and overall moisture management capacity. Uni-directional seam shows higher wetting time at the inner surface as well as better cross-plane transmittance, and hence better overall moisture management capacity as compared to bi-directional stitched and unseamed fabrics. In all the cases, sweat shows less wetting time than water. Multi-layered ensemble with polyester spacer fabric as middle layer exhibits better overall moisture management properties in comparison to layered ensemble with fleece fabric as middle layer both in seamed and unseamed conditions. Seam type plays a most significant role followed by type of layered ensembles then solution type in affecting the overall moisture management behaviour of seamed ensembles.

Design and optimization of multi-scale porous sandwich composites with excellent sound absorption and cushioning properties

Exposure to prolonged or excessive noise has been shown to cause a range of health problems. In this study, flexible sandwich composites (FSCs) with excellent sound absorption and mechanical properties were designed and fabricated by a one-step foaming process. The compound fabric as composite panel and fabric sequence contacted with PU foam has been designed and optimized for excellent cushioning and sound absorption properties. In comparisons of three processing methods for fabricating compound fabrics as reinforced panels of FSCs, punching/hot pressing was found to be the most effective method. Through experiments, the L (low-melting polyethylene terephthalate nonwoven fabric, LPNF) -W (warp-knitted spacer fabric, WKSF) -F (flexible polyurethane foam, FPF) composites had the best performance, reaching the sound absorption coefficient of 0.997 (1000 Hz), 107.77 KPa in compression modulus, 6541 N in maximum impact contact force and 44.68% in impact energy absorption. Morphological study revealed that the transition region formed by FPF and WKSF played a vital role in the L-W-F structure. In that region, small cavities and complex porous paths were observed that effectively improved the sound absorption and cushioning properties by dissipating the stress wave and sound wave level-to-level.

Development of hybrid layered structures based on natural fabric reinforced composites and warp knitted spacer fabric for acoustic applications

This study deals with the development of hybrid layered structures combining natural fabric reinforced composite plates and warp knitted spacer fabric for acoustic applications, and the evaluation of the sound absorption performances. Vacuum infusion technique was used to produce the composite plates. Jute and linen woven fabrics were used as reinforcing materials, and they were impregnated with epoxy resin. The composite plates were combined with warp knitted spacer fabric in different stacking sequences in three-layer structures. All samples were subjected to the measurement of sound absorption property using impedance tube method. The combinations of a single layer and double layers of warp knitted spacer fabric with natural fabric reinforced composite in the appropriate sequences were found to provide superior sound absorption coefficients (SAC) compared to non-hybrid layered structures. Based on the overall evaluation regarding SAC, noise reduction coefficient (NRC), and weight of the structure, the sample with the best performance was regarded as the double layers of spacer fabric backed with a jute fabric reinforced composite plate. The integration of natural fabric reinforced composites with warp knitted spacer fabric had better sound absorption performance compared to the glass fabric reinforced composites, and they were considered to have the potential of being used in interior noise control mainly in vehicles and buildings.

Process development and compression behavior of innovative 3D bi-directional flat-knitted spacer-reinforced composites

3D knitted fabrics are regarded as a viable option for advanced composite materials. Flat-knitted spacer fabrics (FKSF) which are in the category of 3D knitted structures have attracted many attentions due to outstanding characterizations such as high formability and good impact behavior. These structures consist of two surface layers which are linked together by multiple knitted connecting layers. Despite the merits of 3D-FKSFs as composite reinforcements, they have some structural restrictions such as limited thickness. This study aims to develop and characterize bi-directional 3D knitted spacer structures which could be replaced with conventional FKSFs. In the developed structures, the upper and lower surface layers are connected together by two truncated pyramids which can be configurated in any dimensions using an innovative knitting technique. For providing a report regarding their compression behavior, these 3D structures were produced in two different thicknesses on an electronic flat knitting machine. Then, they were impregnated with epoxy resin via vacuum resin transfer molding and the cured composites were subjected to compression force. The results revealed that their compression behavior is similar to the behavior of conventional honey-comb sandwich structures.

A Needle in (Many) Haystacks: Using the False Alarm Rate to Sift Gravitational Waves from Noise

Abstract Yanyan Zheng, Marco Cavaglià, Ryan Quitzow-James and Kentaro Mogushi explain how statistics helps scientists spot ripples in the fabric of space and time

Experimental evaluation of the compression garment produced from elastic spacer fabrics through real human limb

Spacer fabrics found vast applications as medical textile due to their intrinsic and unique properties such as good air permeability, breathability, compressibility and comfort. The aim of this study is to utilize weft knitted spacer fabric as pressure garment to apply more uniform interface pressure on limb than common commercial fabrics. Initially, different weft knitted spacer fabrics by varying the spacer fabric thickness (0.8, 1.2 and 1.8 mm) and elastane yarn content (25, 30, 35 and 40%) were produced. Then, mean interface pressure was obtained through conducting the Mannequin test. Based on the Mannequin test results, spacer fabrics with similar applied interface pressure to commercial one were selected to perform human limb test. According to the results, the spacer fabric with the thickness of 1.8[Formula: see text] and elastane yarn content of 25% not only applied interface pressure comparable to commercial fabric, but also exhibited the most uniform interface pressure mapping on human limb among those studied. Also experimental results showed the superior performance of spacer knitted fabrics with elastane yarn than the single jersey knitted fabrics as pressure garments.

Preparation and characterization of 3D flexible high-distance spacer fabric/foam composite

In order to solve the problem of poor damage resistance of foam, limited thickness of ordinary spacer fabric and complex preparation process of composite, a high-distance spacer fabric/foam composite (HFFC) was designed via a simple and rapid method without molds. The HFFC was composed of two polyvinyl chloride (PVC) faces and a foam-filled high-distance spacer fabric core. Nine kinds of high-distance spacer fabric/foam composites (HFFCs) were prepared by changing the density of the core layer and spacer yarns. The microstructure, compression, bending, thermal insulation, sound absorption and low-velocity impact resistance properties of HFFCs were characterized. Remarkably, the HFFCs with lower foam density have better thermal insulation, sound absorption and low-velocity impact resistance properties while reducing weight. The HFFCs with higher density of spacer yarns exhibit more outstanding compression and thermal insulation properties. In addition, the thermal conductivities of the nine kinds of HFFCs are lower than 0.05 w/(m*K), belonging to high-efficiency thermal insulation material. The developed HFFCs show great potential in many practical applications in packaging, construction and other fields.

Structure of Space Fabric

This paper first proposes that a physical entity such as an electron and a cosmological entity such as a photon belong to two different levels of the Universe. When declaring that space is a vacuum, we are referring to the physical vacuum, and not the cosmological vacuum. The paper propounds that the space we observe is a fabric of cosmological substances. We cannot presume that something fills the emptiness of space. This paper posits that the fab-ric of cosmological substances creates this emptiness to facilitate physical activities such as electromagnetic waves and gravitational pull. Second, the space fabric is a spatial cosmo-logical phenomenon, whereas time is a physical phenomenon operated by a physical entity. The spacetime continuum is created by physical time acquiring the cosmological space fab-ric. The third part of this paper explains the structure and ingredients of the space fabric. The structure itself explains several cosmological phenomena, including electromagnetic waves, gravitation, light, magnetism, dark matter, and dark energy. The philosophical cor-rectness of the paper is validated through the unification of multidisciplinary aspects, and its scientific correctness is validated by its logical consistency with the results of well-known experiments.

Philosophical Approach to Space Fabric and Propagation of Light

First, the paper proposes that a cosmological entity such as a photon and a physical entity such as an electron belong to two different levels of the Universe. The cosmological entities do not have any physical parameters. Thus, several mysteries of quantum physics are still unresolved because both are considered in the same paradigm. This paper further estab-lishes that the spatial space (medium of propagation) is a fabric made of different cosmo-logical substances. It explains how the space fabric plays an important role in creating dif-ferent cosmic phenomena such as gravitation, repulsion, cosmic inflation, and other mys-teries. This spatial space fabric accepts the electromagnetic wave by way of physical time, creating a spacetime continuum. Next, the paper proposes a new vision that explains how an electromagnetic wave transports photons from an emitter to a receiver with a constant velocity by outlining a new paradigm of time and space and precisely treating photons as cosmological substances. This vision explains how the second postulate of Einstein’s special theory of relativity remains valid even if the time dilation due to velocity is not a reality. The correctness of the approach is validated through the results obtained from previous well-known experiments.

Gender, sexuality and space: towards acts of architectural disobedience

Through a contemporary reading of architectural history, this text aims to elaborate on intersectional study of architecture and gender theory. The aspiration is to provide a critical model to overcome the anatomical, formal and identity politics readings that have dominated the study of the relations between gender and architecture so far. When the fabric of space contains a particular set of social relations, what space is granted to those who exist on the margins of white, male subjectivity?

Locally Varying Hubble Parameter in Terms of Reduced Friedmann Equation

Assessment of the Hubble parameter as an indicator of the expansion rate of the universe holds a central position in the field of astronomy. From its initial estimate of about 500 km⋅sec-1⋅parsc-1, this value had been steadily amended as the observational tools became more accurate and precise. Despite this, a gap remains between the value of observations relating to local and nonlocal estimations of the Hubble parameter that gave rise to what became known as the Hubble tension. This tension is addressed here while dealing with space fabric as a cosmological fluid that undergoes transition.

Art

Art Mary Henry Click for larger view View full resolution Untitled I. [End Page 4] Click for larger view View full resolution Rapunzel. [End Page 32] Click for larger view View full resolution Fabric of Space (1966). [End Page 78] Click for larger view View full resolution Chelsea Way (1965). [End Page 178] Copyright © 2021 Perspectives of New Music, Inc

Analysis of the Impact Resistance Capacity of 3D Spacer Fabrics Based on Impact Tests

The article presents the structure influence of distance spacer fabric on the ability to protect against impact based on impact test results of selected packages made of spacer fabrics. The aim of testing these materials was to check their ability to suppress the impact force and absorb the energy in anti-impact vests. The purpose of using these textile materials in protective clothing would be to reduce the weight of the final product, and thus also to reduce heat stress during use. The article contains test results of the force received under an anvil and of the energy absorbed for each of the packages tested. The textile package developed, consisting of three layers, was classified as a protective material because it meets the requirements of EN 13158:2018 Protective clothing – Protective jackets, body and shoulder protectors for equestrian activities. The package provides protection at Level 1, the force received under an anvil during tests was 1.55 kN, and the package absorbed 24.96% of all impact energy. Additionally, the selected package was tested for air permeability.

Computational modelling of hospital mattresses made from spacer fabrics

The appearance of pressure ulcers is a very common occurrence, especially for people with limited mobility who are obliged to spend a long time prone on a support surface. Pressure ulcers in severe cases can cause damage to underlying muscle and bone. Damage to deeper tissues, tendons and joints may also occur. Serious complications, such as infection of the bone (osteomyelitis) or blood (sepsis), can occur if pressure sores progress. While the main strategy for dealing with pressure ulcers is centred around the interaction of patient and care-giver (manually changing the position of the patient every two hours in order to relieve pressure on critical body areas, examination of patient for signs of pressure ulcer formation) there are auxiliary approaches, such as the choice of a pressure relieving support surface. Currently, a variety of support surfaces exists. The criteria of choice are dependent on factors such as the medical history of the patient and economic. The emergence of 3D spacer fabrics as textile materials with good compression behaviour makes them suitable candidates for the production of support surfaces that contribute to the prevention of pressure ulcers. In order to decide on their suitability, extended clinical trials involving actual patients must be performed. In the present paper, a computational methodology utilizing a tool, widely used in the area of engineering namely Finite Element (FE) Method, is proposed as a supporting tool for the preliminary evaluation of the suitability in terms of mechanical behaviour of certain 3D spacer fabrics, providing an insight of the deformation, stress and strain developed on the bodies (human body – mattress) as well as on their interface.

Testing the car seat's comfort

In this paper, four commonly used car seat covers, made from leather as well as from woven, knitted and 3D spacer fabrics are tested as sandwiched and separate layers to determine the effect of the lamination and layers on air and water vapor permeability. Different combinations of interlining materials are also tested to obtain the optimum comfortable car seat cover. This analysis gives us a real idea of which layer negatively affects the breathability of the car seat. The focus of this part of research was to identify the issues within the car seat material instead of factors like external cooling or the clothing of the driver. It was observed that the polyurethane (PU) foam and lamination significantly reduce the permeability of the car seats. The 3D spacer fabric shows the best top layer properties as compared to classical woven, leather or knitted car seat covers. The research shows how layers and lamination cause thermo-physiological discomfort of car seats.

Novel weft-knitted spacer structure with silicone tube inlay for enhancing mechanical behavior

A novel structure that integrates an inlaid silicone tube in the connective layer of spacer fabric is developed to increase its compression resistance and impact force absorption. Two inlaying methods are proposed to evaluate the effect of the spacer yarns, presence of the inlay, and inlay density and pattern. The results show that a silicone inlay effectively increases the compression resistance and impact force absorption. The compression behavior of the fabric can be modified with different inlay patterns and stitch densities. An inlaid silicone tube reinforces the structure and provides spacer fabrics with a better performance as a cushioning material.