Multilayer Woven Research Articles

The influence of deformation waves on impact energy absorption and heat release in multi-layer woven fabric ballistic body armor

The mechanical and thermo-mechanical damage mechanisms of a multi-layer woven polymeric fabric ballistic body armor are analyzed. A proposed two-stage model takes into account the wave interaction between an impacting element and an armor package at the initial stage of the collision. The model allows the prediction of initial fabric compaction and the estimation of velocities and displacements. These can then be used to predict the response of a layered flexible barrier and the contribution of stresses and frictional forces in causing permanent deformation.

Custom-Made Reinforcement Structures Made of Inorganic Fibers Challenges, Chances and Technical Approaches

Ceramic fibers are just as glass and basalt member of the group of inorganic fibers. Like most types of inorganic fibers ceramic fibers have a high tear resistance but a limited flexibility. [1] Ceramic fibers are characterized by their extraordinary high temperature and chemical resistance. These properties make them interesting for different high technical applications, as they occur in aerospace, chemical-and energy technology. In this field, they are applied especially as a reinforcement component in composite materials. Not only the partially high material price, but although the typical brittleness of ceramic fibers bring huge problems during the textile production chain, which limits the availability of complex textile preforms in the market. Often, a radical revision of the machine and processing concept is necessary to enable an economical production process. The Application Center for Textile Fiber Ceramics TFK at Fraunhofer-Center for High Temperature Materials and Design HTL develops and modifies textile production processes to make them suitable for the special requirements of ceramic fibers. One and multilayer woven fabrics, braids and tape structures for the winding process have already been successfully implemented. A further development complex is the intensive investigation of three-dimensional textile reinforcement structures. Regarding the high material costs, these research activities are very important. If the textile reinforcement is placed only where needed, the amount of used fiber material can be reduced significantly.

Motorized Jacquard technology for multilayer weaving damages study and reduction: Shed profile and close shed profile

Materials used for composite reinforcements usually have high mechanical performances which are linked to a very sensitive and brittle behaviour to friction. The weaving process applied to delicate yarns, like glass, carbon and some other technical yarns, generate damages which tend to reduce the performances of the final composite. Shedding may be a major weaving stage for the generation of yarn damages. Based on a specific weaving pattern, it was observed that different shedding configurations could influence yarn damages at the shedding step. The specificity of the motorized Jacquard device is used to generate different movements and geometry configurations. A particular methodology needed to be set in order to confirm these observations and bring out a clear effect of shedding parameters on yarn damages. After damages have been identified and classified, some experiments will count the damage occurrences and evolutions in time according to shedding parameters. The aim of this research is first to show a clear effect of shedding on warp damaging thanks to the quantification of damages and then to set out an optimized configuration of shedding parameters which may reduce deterioration involved in high-density multilayer woven fabrics.

Dissipation mechanisms and FE-modelling of penetration processes in multilayer aramid barriers of various weaving types

Experimental investigation and computational estimation of the ballistic resistance properties of the multilayer fabric barriers which include layers with various weaving types carried out. Plain and four patterns of twill weave fabrics were concerned. The dynamic interaction of multilayer woven barriers with two forms of impactors is considered, and the processes of energy dissipation are investigated using the FE-modelling of impact processes. Verification of the FE-models is carried out by full-scale ballistic experiments, and the simulation error is estimated. The contribution of various mechanisms to the energy dissipation of the impactor is evaluated. The influence of the placement of layers with different weaving types in the woven barriers on the impactor velocity after the rupture is analyzed numerically. The advantages of some particular combinations of weaving types placement in comparison with the uniform barriers with the same number of layers is shown.

Prediction of Gas Permeability of Multilayer Woven Reinforcements for SiCf/SiC Porous Composites

The permeability is a key property of SiCf/SiC porous composites using as filter in high temperature. In this study, an analytical model based on Hagen–Poiseuille flow was used to investigate the relationship between the structural properties and the filtration performance of the fiber architecture, including fabric and stitched preform. The air flow through the fabric was considered in two different regions: inter-yarn and inter-fiber, as well as the pore properties of the fabrics. The key feature of the model was that the parameter of flow channel based on the pore shape was taken account into the calculation of the equivalent pore size. After determining the pore characteristics, the flow rates of the pore unit cell were obtained; subsequently, permeability of the fabrics and stitched preforms were predicted to compare with the experimental ones. This turns out that the analytical model shows a good correlation between the experimental and predicted permeability values, and the difference between different woven-type fabrics was well presented.

The influence of the weaving pattern on the interface friction in aramid fabrics under the conditions of the transverse loading

Experimental investigation and computational estimation of the interface friction in aramid woven fabrics for different weaving types are performed under the conditions of the transverse compression. The required range for the compressive loads is estimated by the use of FE-modelling of impact loading of the multi-layer woven barriers. For the moderate values of transverse compression the simple sliding test for two fabric layers under the conditions of the transverse pressure was carried out. The parameters of friction are determined for the cases of textile-textile interfaces for different weaving types. It is obtained that the combination of fabrics of different weaving types can have the mutual static friction coefficient differing from the coefficients for each component up to 20%. Moreover, it can also differ from the averaged value of these two coefficients. For the higher values of the transverse compression the experimental equipment is proposed and designed for pulling out a textile layer from a free multilayer structure of fabrics under the conditions of controllable transverse compression loading. The numerical modelling of the load distribution in the tested fabric layer is accomplished which allows us to estimate the irregularity of the transverse pressure in the specimen and to correct the experimental results for friction coefficients. The transverse elastic modules used in these simulations were obtained separately by means of compression tests for the multilayer fabric samples. All the friction tests were carried out using Zwick/Roell 100 experimental device and the results are presented for various pulling rates and transverse loads. It is obtained that the pulling rate has a weak influence on the interface textile friction in the range of rates under consideration.

Two Dimensional (2D) P-Aramid Dry Multi-Layered Woven Fabrics Deformational Behaviour for Technical Applications

In today’s scenario for the various technical applications, from composites to body armour, the material mouldability along with its mechanical property become very important. In the present study, two dimensional (2D) woven fabrics made of para-aramid high performance fibres in multi-layer dry structure were used for investigating different forming characteristics. The different layers were arranged with 0°/90° orientation for deep drawing formability test to analyse the effect of number of layers and blank-holder pressure (BHP) during the test. Specific preforming device with low speed forming process and predefined hemispherical shape of punch has been applied. Using fine photographic analysis, some important 2D multi-layer fabrics forming characteristics i.e., material drawing-in, surface shear angle etc. from the imposed deformation have been observed, measured and analysed for better understanding and co MPa rison. The result revealed that the mouldability behaviour of the multi-layered dry textile fabric preforms is directional, and closely dependent on blank-holding pressure and number of layers. This indicates both parameters should be carefully considered while material deformation to avoid the formation of wrinkling and maintain other mechanical properties on final application.

Quality Control of Armor Fabric by Modeling Thermomechanical Processes under Projectile Impact

Mechanical and thermomechanical processes of interaction between a projectile and the multilayer woven barrier made of a polymer fabric are considered. A simplified mathematical model is proposed to describe the deceleration of the projectile due to the dissipation of energy spent on irreversible stretching deformation of fabric fibers, fiber slip friction, and barrier material heating. The parameters of governing equations are estimated by means of identification based on experimental data. Results of a computational experiment using the mathematical model can be employed for the diagnostics of armor protection based on the measurements of dynamic temperature fields.

A Rheological Model of the Influence of Thermal Exposure on the Viscosity of a an LBS-4 Varnish during Impregnation of a Multilayer Woven Blank of a Heat-Protective Coating

A rheological model of LBS-4 bakelite varnish that is used in the fabrication of heat-protective coatings of reentry spacecraft is developed on the basis of experimental data that highlight the dependence of the dynamic viscosity of a varnish on the duration of its long-term storage and thermal-exposure parameters (time and maximum temperature). This model is shown to be useful in the design of impregnation of woven-fiber blanks for the fabrication of composites. The relationships for evaluating the impregnation area under various technological conditions are described as well.

Study of influence of interlocking patterns on the mechanical performance of 3D multilayer woven composites

Three-dimensional multilayer woven composites are mostly used in high-performance applications due to their excellent out-of-plane mechanical performance. The current research presents an experimental investigation on the mechanical behavior of three-dimensional orthogonal layer-to-layer interlock composites. The glass filament yarn and carbon tows were used as reinforcement in warp and weft directions respectively, whereas epoxy was used as a resin for composite fabrication. Three different types of orthogonal layer to layer interlock namely warp, weft, and bi-directional interlock composites were fabricated and the effect of interlocking pattern on their mechanical performance was evaluated. The evaluation of the mechanical performance was made on the basis of tensile strength, impact strength, flexural strength, and dynamic mechanical analysis of composites in warp and weft directions. It was found that warp and weft interlock composites showed better tensile behavior as compared to bi-directional interlock composite both in the warp and weft directions, due to the presence of less crimp as compared to the bi-directional interlock composite. However, the bi-directional interlock composite exhibited considerably superior impact strength and three-point bending strength as compared to the other structures under investigation. These superior properties of bi-directional interlock composites were achieved by interlocking points in warp and weft directions simultaneously, creating a more compact and isotropic structure. Tan delta values of dynamic mechanical analysis results showed that bi-directional interlock composite displayed the highest capacity of energy dissipation in the warp and weft directions while weft interlock structures displayed highest storage and loss moduli in the warp direction.

Damage to a Multilayer Woven Composite by Low-Velocity Indentation with a Rigid Spherical Indenter

The results of experimental studies of damage to a layer of a woven composite by pressing steel spherical indenters are presented. The effect of the indenter-curvature radius on the structure of the localdamage area of the composite and the effect of the local damage on the strength of initially equistrength composites under tension along the principal directions of layer reinforcement are determined.

Completely integrated multilayered weave electro-textile antenna for wearable applications

This paper proposes a unique, first of its kind fabrication technique for the making of textile antennas. A novel method that provides scope for automation in textile antenna production is presented here. A completely integrated textile antenna fabrication method that eliminates the tasks of positioning and fastening of the various components of a patch antenna is discussed. The technique employs multilayer weaving for the production of a wearable antenna on a cotton substrate. Silver yarn is used for the conductive regions of the textile antenna. Two layers of woven cotton serve to isolate the radiating patch from the ground plane of the antenna. The designed antenna was chosen to operate at the frequency of 2.45 GHz for Wireless Local Area Network. The built prototype resonated at 2.43 GHz with a |S11|of −18.62 dB. The integrated textile antenna exhibited a gain of 1.06 dBi at 2.43 GHz.

Modeling of thermomechanical processes in woven composite material at blow by the striking element

The paper studies mechanical and thermomechanical interaction processes between striking element and multilayered woven barrier made of polymeric fabric. A simplified mathematical model is proposed. This model describes the inhibition of the damaging element due to energy dissipation, that is spent on irreversible strains of fabric threads stretching, friction during the mutual slippage of threads and barrier material heating. The defining equations parameters are estimated by identification according by the experimental data. The computational experiment results using the mathematical model can be used to diagnose armor protection according to the measurement of dynamic temperature fields.

Investigation of multi-layered woven car seatbelts with optimum performance

This work was aimed to study the mechanical properties of multilayered woven automobile seatbelt by varying the weave design, fabric density and material. Three layered woven webs were produced in three different weaves (twill, matt and combination of plain and matt named here as “combo”). The webs were produced either in polyester, Polyamide (Nylon) or by using combination of both.The seatbelts produced in matt weave were able to bear more load before rupture as compared to twill and combo weaves. The effect of actual thread density and fabric areal densityon the breaking strength of seatbelt was found. Finally, a low cost seat belt having minimum fabric areal density and optimum strength was proposed.

New Approach to the Designing of Curtains – Decorative Multilayer Woven Structures

New Approach to the Designing of Curtains – Decorative Multilayer Woven Structures

On the influence of fabric layer shifts on the strain distributions in a multi-layer woven composite

The influence of the relative shift between fabric layers on the local strain distributions at the mesoscopic scale of a four-layer plain weave glass fiber/epoxy matrix composite is studied through Finite Element (FE) modeling. The surface strain fields of several representative unit cells, consisting of compacted and nested plain weave layups with different layer shifts and the matrix complement, are compared to strain fields measured experimentally by digital image correlation. The layer shifts only have a small impact on the calculated homogenized macroscopic mechanical properties. However, the local strain fields are influenced significantly. Good quantitative agreement is obtained between the measured surface strain distributions and the numerical results if the layer shifts of the tested specimen are used in the FE model. The most frequently used models without layer shifts or with maximum nesting do not provide satisfactory surface strain distributions.

Three-dimensional of crinkles effects using multilayer woven fabrics containing spandex

Three-dimensional of crinkles effects using multilayer woven fabrics containing spandex

Development and characterization of three-dimensional woven-shaped preforms and their associated composites

Three-dimensional multilayer woven preforms are mostly used in high-performance composite applications due to their better in-plane and out-of-plane mechanical properties. The present study aims to produce and characterize multilayer flax yarn-based three-dimensional-shaped preforms and their corresponding composites. The T- and H-shaped three-dimensional woven preforms were prepared on conventional dobby loom using two types of weaving pattern, i.e., layer-to-layer orthogonal and through thickness orthogonal. Composites were fabricated using open mould technique. Peel strength of T- and H-shaped structures was investigated and compared with laminated structures. Mechanical properties of layer-to-layer-interlocked structures in T and H shapes were found better than TT and laminated structure, both for reinforcement and composite.

Jacquard UNIVAL 100 parameters study for high-density weaving optimization

3D structures for composites, and especially 3D woven preforms use, is growing because of high-performance fibres improvements, field diversification and applications complexity. Critical industries like the air-space industry need a perfect control of processes and products’ final properties. Among other 3D weaving techniques, multilayer weaving is interesting for the diversity and complexity of possible 3D structures. A new Jacquard shedding technology called UNIVAL 100 which can be used with multilayer weaving, has appeared few years ago and uses actuators instead of the traditional Jacquard hooks. It is synonym of great improvements, as such a technology should enable controlling perfectly the way yarns are moving during shedding. The aim of this paper is first to describe their operating mode. It is our basis for a design of experiments development, the purpose of which is to experimentally determine the effects of UNIVAL parameters on process quality, in the case of high-density multilayer woven fabrics (which we will further call HDMW fabrics).

ИССЛЕДОВАНИЕ ЛОКАЛИЗАЦИИ АДИАБАТИЧЕСКОГО СДВИГА В МЕДИ МАРКИ М1 МЕТОДОМ СОСТАВНОГО СТЕРЖНЯ ГОПКИНСОНА

Experimental-computational investigation of dissipative factors in the process of impacting and penetrating of barriers made of woven aramid fiber composites is presented. Various types of 2D woven layers (13 types) are considered, as well as some characteristic types of transversal sewing as modifications of 3D weaving. It is found out that the main dissipative factor in penetrating woven barriers of relatively small thickness (up to 10 layers) is increasing of the kinetic energy of fibers, not the traditionally considered losses on friction and failure. In corroboration of this result, it is shown that transversal sewing of a multilayered woven composite used for increasing its bending stiffness, but, in doing so, limiting the displacement of fibers, does not contribute to increasing the protective properties of the barriers. Keywords: puncture, failure, multilayered obstacles, energy dissipation, aramid fibers, woven composites, types of weaving, transversal sewing. &nbsp