Backing Material Research Articles

Mesoscale modeling of S-2 glass/SC-15 epoxy composites: Plain-weave architecture

S-2 glass composites can readily serve as backing materials for armor systems due to their light weight and tensile properties. However, high-fidelity ballistic modeling of these composites requires accurate predictions of their nonlinear deformation and failure behaviors, which can prove challenging. This paper describes simulations of a plain-weave S-2 glass composite at the mesoscale using a mesh geometry that individually models the S-2 glass yarns, epoxy resin matrix, and yarn/matrix interfaces as separate entities. Simulation results are compared to a wide variety of mechanical tests designed to measure the response of the composite to tension, shear, and delamination. Although the individual yarns, matrix, and interfaces are described using relatively simple material models, the overall composite model can accurately reproduce behaviors such as nonlinear deformation, yarn breakage, and delamination in both tension and shear.

Plasma-Assisted Preparation of High-Performance Chitosan Nanofibers/Gauze Composite Bandages

In this work, novel composite bandages were prepared by electrospinning chitosan nanofibers on 100% cotton substrate fabric. In the composite bandages, chitosan nanofiber web serves as a primary wound dressing whereas cotton substrate as a backing material. Cotton substrate was given plasma pretreatment and composite bandages were given plasma posttreatment to improve the durability of composite bandages and adhesion between nanofiber and cotton substrate layers. The adhesion of the nanofibers to the substrates was assessed by qualitative and quantitative techniques. Plasma pretreatment of the substrate with 100% helium and 99% helium/1% oxygen plasmas showed up to four times increase in force required to peel off the nanofiber layer. Even more increase in adhesion was obtained when composite bandages were given plasma pretreatment to substrate as well as posttreatment to composite bandages. Storage modulus, glass transition temperature, and crystallinity of untreated He and He/O2-plasma treated chitosan nanofiber web were studied to observe the effect of plasma treatment on the chitosan nanofibers using dynamic mechanical analysis, differential scanning calorimetry, and wide angle X-ray diffraction, respectively. To understand the mechanism of improved adhesion, surface elemental analysis of plasma treated chitosan nanofibers and cotton substrate was carried out using X-ray photoelectron spectroscopy.

Selected Aspects of Numerical Analysis of Layered Flexible Structures Subjected to Impact of Soft Core Projectile

Abstract The aim of the study is to identify the relevant aspects of numerical analysis of impact of projectiles with soft cores into a package composed of thin flexible plies located on the plastic backing. In order to illustrate the problem, normal impact of 7.62 mm TT projectile into an unclamped package comprising 36 plies of Dyneema SB71 supported on the plastic backing was selected. The problem was solved with the use of the finite element method (FEM) with the explicit integration scheme (central difference method) of motion equations in the matrix form. Based on the conducted numerical computations, it was revealed that obtaining the extreme deformations of a projectile soft core and the backing material in Lagrangian description requires employment of adaptive methods. The proposed R-adaptive method performs its role but must be used carefully due to the mass loss which may appear during calculations.

Development of method to remove weld scallop and ceramic backing material of wedge type and its application

The weld scallop has been used for joining T-bars. There are a lot of weld scallops in shipbuilding. It is difficult to perform scallop welding due to the inconvenient welding position. This results in many problems such as porosity, slag inclusion, etc. In this study, a new method is devised to remove weld scallops by incorporating a Ceramic Backing Material (CBM). The weld scallop is removed by an elongation of the v groove. In order to insert a CBM into the groove without a weld scallop, a wedge-shaped CBM is developed. The top side of the developed CBM is similar to the shape of a general back bead. The bottom surface has a saw-toothed shape for cutting at a suitable length. This can be attached to the root side of a face plate using adhesive tape, just like a general CBM. Welding experiments in normal and abnormal conditions are carried out and the possibility of burn-through is examined. This CBM’s applicability to shipbuilding is verified.

Straight Through Hole Drilling in Machinable Ceramics

This paper presents a unique through hole forming method in machinable ceramics using a flowable backing material during nanosecond pulse UV laser radiation. While processing through holes, the flowable backing material is arranged to be in contact with the back side of machinable ceramics, i.e., surface of laser beam's exit side. The laser beam which penetrated machinable ceramics strikes the flowable backing material and superheated plasma is generated by the laser beam’s absorption into the flowable backing material around exit hole. The induced plasma is elevated with the flowable backing material from the back side of machinable ceramics to the front side of that by a capillary phenomenon, and the shape of through holes changed from tapered shape to straight shape by the elevation of plasma. Through this technique, we are able to make substrate for a probe card which has straight shape holes with narrow pitch.

The conservation and mounting of the Canadian Pacific Railway (CPR) Charter

In preparation for installation within the Glenbow Museum's updated Alberta history exhibition, Mavericks, a variation of Irene Karsten's peel test was used to test four adhesives (wheat starch paste, Jade 403, Paraloid™ B72 and Lascaux™ 360HV:498HV mix) to evaluate their appropriateness for display mounting the Canadian Pacific Railway (CPR) Charter, an historically important Canadian parchment document. Variations on thread mounts and Mylar™ hinges were investigated, as were possible backing materials. Once on display, a loss of environmental control in the gallery during a construction project subjected the mounted parchment to environmental stresses. The mounting system worked successfully to limit damage to the parchment, with the adhesive bonds between the threads and parchment failing but without damaging the artefact.

Digital imaging: the application of shape-from-shading to lace, seals and metal objects

This article explores one application of a digital imaging technique to historic objects and online delivery of the virtual object. Shape-from-shading is a computer algorithm used to reconstruct three-dimensional shapes from two-dimensional images. The Digital Epigraphy and Archaeology (DEA) project used shape-from-shading to develop a digital website and toolbox to enhance computer-assisted examination of inscriptions preserved as ektypa. This article reports the results of a project to see if the DEA website and toolbox could be used with other materials and objects with information-rich textured surfaces. Seventeen samples were tested, including lace-like textiles placed on different backing materials; wax seal impressions made from a range of materials; and excavated metals. It was found that image capture with a flatbed scanner achieved better results than a multi-functional printer, and that the unprocessed flatbed scan images were sometimes more informative than digital photographs. It was possible to modify the DEA algorithm for both the lace-like samples and the seal impressions to obtain good three-dimensional (3D) reconstructed images. However, this was not possible with the metal samples due to the nature of the material. The 3D reconstructed images are useful to online users in providing an interactive resource that can be manipulated by the user, rather than a two-dimensional (2D) image.

Study on the Arrangement of Fabric Materials for Multi-Layer Soft Body Armor Based on their Mechanical Properties

Abstract The arrangement of protective material of bullet proof vest is important for face and back strike when all backing materials are hybrid. In this paper, three hybrid protective materials, as UD aramid fabric, Polyethylene (PE) and laminated woven aramid fabric (Argus) were used in this work. The bullet proof vest made of these combinations of materials to wear flexible and comfortable. It was found that the mechanical properties, as work of rupture of material, Young's modulus, bursting strength and penetration stroke at bursting, give trend to arrange the face and back strike for bullet proof vest, the increasing of work of rupture enables energyabsorbing mechanisms and the materials with high work of rupture enable to absorb energy to predict the arrangement of the layers before shooting.

Reverberation Reduction in Capacitive Micromachined Ultrasonic Transducers (CMUTs) by Front-face Reflectivity Minimization

Front-face acoustic reflectivity of ultrasonic imaging transducers, due to acoustic impedance mismatch with the propagation medium, may cause reverberation phenomena during wideband pulse-echo operation. Front-face reflectivity may be reduced by promoting the transmission of the echoes, received from the medium, to the transducer backing, and by maximizing the mechanical-to-electrical energy conversion and dissipation by tuning the electrical load impedance connected to the transducer. In Capacitive Micromachined Ultrasonic Transducers (CMUTs), the energy transfer from the medium to the backing is very low due to the large impedance mismatch between the medium and the transducer substrate, typically made of silicon. Reverse Fabrication Process (RFP) makes it possible providing CMUTs with custom substrate materials, thus eliminating the original silicon microfabrication support. In this paper, we propose two methods for the front-face reflectivity reduction in RFP-CMUTs: the first one is based on the use of low-impedance, highly attenuating backing materials, and the second one is based on the maximization of the mechanoelectrical energy conversion and dissipation. We analyze the methods by finite element simulations and experimentally validate the obtained results by fabricating and characterizing single-element RFP-CMUTs provided with different backing materials and electrical loads.

Quantitative analysis of very small quantities of cultured cells

In this paper, methods of quantitative elemental analysis of very small quantity of cultured cells were developed. First of all, an internal-standard method for the solution containing cells whose density is more than 1 × 106 cells/mL was established and then a standard-free method for cultured cells was developed. It was confirmed that the method allows us to quantitatively analyze more than 25 elements in the samples containing only 20,000 cells. Also, the methods for removing cultured cells from a flask were examined in order to improve accuracy and sensitivity of analysis since the use of trypsin and PBS sometimes brings a large amount of sodium, phosphorus and potassium, which have direct effect upon accuracy of analysis based on the standard-free method. It was found that the method of removing cells with a scraper without using trypsin and PBS is the best manner. Also, the effects of using thinner backing materials were examined in order to improve sensitivity of analyses. It is expected that accurate analysis of samples containing nearly two thousand cells is possible on the basis of the standard-free method when using a thinner backing material.

Numerical and experimental study of armour system consisted of ceramic and ceramic- elastomer composites

Abstract The paper presents numerical and experimental results in the study of composite armour systems for ballistic protection. The modelling of protective structures and simulation methods of experiment as well as the finite elements method were implemented in LS DYNA software. Three armour systems with different thickness of layers were analyzed. Discretization for each option was built with three dimensional elements guaranteeing satisfactory accuracy of the calculations. Two selected armour configurations have been ballistically tested using the armour piercing (AP) 7.62 mm calibre. The composite armour systems were made of Al2O3 ceramics placed on the strike face and high strength steel as a backing material. In case of one ballistic structure system an intermediate ceramic- elastomer layer was applied. Ceramic- elastomer composites were obtained from porous ceramics with porosity gradient using pressure infiltration of porous ceramics by elastomer. The urea-urethane elastomer, as a reactive liquid was introduced into pores. As a result composites, in which two phases were interconnecting three-dimensionally and topologically throughout the microstructure, were obtained. Upon ballistic impact, kinetic energy was dissipated by ceramic body The residual energy was absorbed by intermediate composite layer. Effect of the composite shell application on crack propagation of ceramic body was observed.

Experimental and numerical investigation of fabric impact behavior

This paper presents experimental and numerical research regarding blunt trauma resistance of ten fabrics made of high strength fibers. Fabrics of various architecture were examined, including plain woven fabrics, unidirectional laminates and multiaxial fabrics. The fabrics were compared with respect to the depth of the depression formed and the amount of energy transferred to the backing during projectile impact. Absolute values of mentioned parameters were compared, as well as their values after normalization with respect to thickness and areal density of the fabrics. A numerical method for estimating the amount of energy transferred to the backing was proposed.Normalized results, obtained experimentally and numerically, proved that most of the analyzed fabrics provide a similar level of protection, but the best blunt trauma resistance is given by multiaxial fabrics and the least by plain woven fabrics. This study has also shown that the depth of the depression in the backing material is an insufficient parameter in describing protective properties of fabric against blunt trauma. It is possible that impacts into ballistic packages composed of different fabrics with the same depth of depression may cause completely dissimilar injuries because of the amount of energy transferred to the backing material.

논-스캘럽 블록 조인트 용접법 개발

Abstract A weld scallop is a small quadrant or half circle type hole installed in the weld line cross area for easy welding operation. Many types of T-bars with a scallop can be welded in a block assembly stage in shipbuilding. The difficulties arise from the fact that scallops are to be filled by build-up welding after welding of the cross line is complete. In this study, a non-scallop block joint welding method was developed using special type CBM (ceramicbacking material). The wedge shaped CBM was devised to insert a CBM into just the V groove of weld line crossarea without weld scallop. A saw-toothed shape was adopted for easy cutting of the unnecessary part in the CBMfitting process. The applicability of the developed method was verified through welding experiments based on the yardwelding conditions. Key Words : Weld scallop, Build-up welding, Block assembly stage, CBM(ceramic backing material) 이 논문은 2014학년도 동의대학교 교내연구비에 의해 연구되었음(2014AA007). * Corresponding Author : Dae-Eun Ko(Dong-Eui Univ.)Tel: +82-51-890-2594 email: deko@deu.ac.krReceived May 8, 2014 Revised June 17, 2014 Accepted September 11, 2014

The role of isotope ratio mass spectrometry as a tool for the comparison of physical evidence.

This paper considers how likelihood ratios can be derived for a combination of physical, chemical and isotopic measurements. Likelihood ratios were formulated based on the characteristics of a small convenience sample of 20 duct tapes. The propositions considered were: The physical and isotopic characteristics of ten rolls of duct tape were shown to be consistent throughout each roll. The width and thickness of the tapes and the density of the scrim fibres provided equivalent information and the combined physical characteristics provided a basis upon which to discriminate between many of the samples. Scatter-plots and confidence ellipses provided a convenient method to group the isotopic composition of the tape backing material and provided a basis to discriminate between samples which were physically indistinguishable. Considering both the physical and isotopic characteristics it was possible, at best, to ascertain that the evidence provided moderately strong support for the proposition that two samples of tape were derived from the same batch (LR=400). Kernel density estimates were used to model the distribution of isotopic compositions of the backing material. Using this technique it was possible to estimate objectively the probability that a sample with given characteristics could be drawn, at random, from the background population and to calculate a likelihood ratio based on the propositions above. The strength of evidence which could be presented by either model was ultimately limited by the size of the background sample.

Validiation of Photometric Ellipsometry for Refractive Index and Thickness Measurements

We design and build a photometric ellipsometer that can be adjusted or modified to match specific needs for different experiments. To validate our setup, we test the system with glass substrates at multiple incident angles from 30° to 70°. The experimental data can then be fitted to the standard theoretical model for ellipsometry with a single interface, allowing the amplitude ratio (tan Ψ) and the phase difference (Δ) to be evaluated as fitting parameters. As a result, we obtain the refractive indices of glass as 1.44–1.55 depending on the backing material. By the same means, it is also feasible to derive thicknesses of silicon oxide films. The resulting thicknesses are in good agreement with those determined by a commercial ellipsometer with the minimum deviation of 0.2 %.

Destruction of thin films with damaged substrate as a result of waves localization

The present paper is devoted to an issue of possible localization of waves propagating within a structure that consists of a film connected to a backing material by a substrate. The substrate is initially damaged. In the first approximation, the film model in the present paper is assumed to be a string on an elastic foundation with a coefficient depending on the substrate damage degree. The elastic foundation imitates the substrate and backing material effects on the film. Initiation of a string delamination resulted from the structure damaged at localized oscillations caused by impact loads has been considered. At loading, the initial damage of the substrate is changing in time and space according to the proposed law of the damage growth. It has been shown that at impact the cause of the string substrate material damage increase can be localized oscillation modes. The localized mode existence depends on the relation between initial substrate rigidity and main material rigidity. The impact energy is redistributed between propagating waves and localized waves in such a way that the latter make the main contribution to the growth of the material damage.

Frequency characteristics of receiving sensitivity and waveform of an anti-acoustic cavitation hydrophone

Novel anti-cavitation hydrophones were fabricated by depositing a hydrothermally synthesized lead zirconate titanate polycrystalline film on the back of a titanium plate. These hydrophones were not damaged by the measurement of the acoustic field formed by a high-intensity focused ultrasound (HIFU) device. The hydrophones were designed using Mason’s equivalent circuit and by numerical simulation to improve their receiving characteristics for the measurement of the HIFU device. High receiving sensitivity with flat frequency characteristics was obtained by using a backing material with a specific acoustic impedance of about 20 × 106 kg/(m2 s) [Rayl]. We developed a new type of hydrophone using a tin and titanium rods as backing materials, which have specific acoustic impedances of 24 × 106 and 27 × 106 kg/(m2 s), respectively. The fabricated anti-cavitation hydrophone showed wide frequency characteristics of the receiving sensitivity. Furthermore, we observed the output waveform with distortion due to nonlinear propagation using the fabricated anti-cavitation hydrophone. This hydrophone was not damaged by exposure to a high-intensity acoustic field of an ultrasound cleaner under acoustic cavitation for duration of about ten times longer than the conventional commercial hydrophone.

Fabrication of 1-3 Cement-Based Piezoelectric Ultrasonic Sensors for NDE Applications

This paper described fabrication and comparison of embedded ultrasonic sensors for NDE applications. A 1-3 cement-based piezoelectric composite was used as the sensing element of the ultrasonic sensor. As a front matching layer between test material and piezoelectric materials, cement/epoxy resin was selected. In order to make the backing materials for sensors had enough acoustic attenuation performance, the backing material of sensors doped with tungsten powder. When the mass ratio of tungsten/cement backing was two and the thickness of cement/epoxy resin front-face matching was 3mm, the 1-3 cement-based piezoelectric ultrasonic sensor showed a significant enhancement in both relative pulse-echo sensitivity and-6dB bandwidth. These promising results suggested the great potential for developing high-performance ultrasonic sensors using the 1-3 cement-based piezoelectric composite.

Evolution of the lubrication regime of a cylindrical journal bearing in the starting phase

Purpose – The paper aims to analyze the evolution of the lubrication regime by studying the variation of friction coefficient with the rotational speed of the shaft and the impact of the applied load in the starting phase of a cylindrical journal bearing. The paper also aims to ensure that the oil layer is large enough for the rough edges of the outer layer of the bushing and the shaft cannot come into contact. The bearing is made of steel backing material and babbitted (88 per cent tin) on its inner surface. Design/methodology/approach – A numerical analysis is performed taking into account the thermal effect to better predict the operating performance of a hydrodynamic plain cylindrical journal bearing during the start-up and observe the variation of the heat production in bushing inner surface. The flow is modeled based on the Reynolds equation and discretized using the finite volume method. Findings – The evolutions of the start-up speeds of the bearing have remarkable influence on friction torque; average temperature and dissipated power increased with increasing speed and increasing load, but the maximum pressure and the eccentricity decreased with the increase of the start-up speed. The friction coefficient, minimum film thickness and attitude angle increase with elevation of start-up speed. Originality/value – For the start-up speed of 750, 1,000 and 1,800 rpm and an applied load of 1,000 N, the regime of lubrication of the bearing passes the hydrodynamic regime to the mixed regime; therefore, during start-up and under heavy loads, the bearing must move very quickly at these speeds to avoid contact of the inner surface of the bearing and the shaft.

Through Hole Forming Method Using a Flowable Backing Material During Pulse UV Laser Radiation

*1 Department of Electrical and Electronic Systems Engineering, Nagaoka National College of Technology 888 Nishikatakai, Nagaoka, Niigata 940-8532, Japan E-mail: snaka@nagaoka-ct.ac.jp *2 Itagaki Kinzoku Co., Ltd., 1628 Hitotsuyashikishinden, Sanjo, Niigata 959-1152, Japan E-mail: k-itagaki@e-call.biz *3 Wavelock Advanced Technology Co., Ltd., 13F Seroka Tower, 8-1 Akashi, Chuo, Tokyo 104-0044, Japan E-mail: n-soma@wavelock-at.co.jp