Microstructures and electromagnetic interference shielding effectiveness of ME21/Mg laminated materials by accumulative roll bonding

Laminated composite with multi-layer interfaces has better electromagnetic interference shielding performance, which has attracted great attention. In this work, magnesium matrix laminated structure materials were prepared through Accumulative Roll Bonding (ARB). Microstructure, electrical conductivity and electromagnetic interference (EMI) shielding effectiveness (SE) of ME21/Mg laminated materials were investigated to understand the effect of layered structure and the change of microstructure on the electromagnetic shielding property. The results showed: the precipitated secondary phase and introduced interfaces could provide multiple reflections, attenuate the electromagnetic waves and improve the SE value. The electrical conductivity of 2-cycle increased to 21.04*106S/m，which was 17.74% higher than that of ME21 alloy, the intensity of texture of ME21 layer increased with the rolling passes, which contributed to the improvement of the electrical conductivity as well as the attenuation of reflection. The layered composite exhibited better shielding effectiveness compared with the ME21, in the 8.2-12.4 GHz test frequency, the SE was 98-107dB. The shielding mechanism of layered materials was explained, which provided guiding for the efficient shielding of electromagnetic waves.

A hybrid method of predicting the acoustical properties of multi-layered materials

Many numerical and measuring approaches are widely used in predicting and analysing the acoustic performances of laminated materials for noise control applications. However, numerical methods generally require a set of non-acoustic parameters, and the measuring methods are not available for exceedingly thick materials. The main aim of this article is to address a hybrid approach of evaluating the normal incidence sound transmission loss and absorption coefficients of multi-layered materials. This method is performed with some special parameters that contain the sound transmission and reflection coefficients of each sub-layer of a multi-layer specimen and can be measured by a standing wave tube system. The accuracy and feasibility of the present method are validated by the experimental and numerical comparisons between different methods and samples. Moreover, this present approach can be applied as a numerical tool of estimating the acoustical behaviours of multi-layered structures in noise control treatments, such as automotive, building and aerospace industries.

BENDING CHARACTERISTICS OF LAMINATED WOOD COMPOSITES CONSTRUCTED WITH BLACK PINE WOOD AND ARAMID FIBER REINFORCED FABRIC

The aim of this study was to determine the 4-point bending strength and modulus of elasticity in bending of Black pine wood laminated materials reinforced with aramid fiber was bonded using epoxy or polyurethane glues separately. The samples were prepared in accordance with the TS 5497 EN 408 (2006). The results of the study determined that the highest value for static bending strength was found in the laminated wood samples (83.94 N.mm-2) that were prepared using inter-layer aramid fiber reinforced polymer (AFRP) and epoxy glue. The highest value of modulus of elasticity in bending was found in the samples prepared with inter-layer epoxy and AFRP (10311.62 N.mm-2). It was observed that the samples parallel to the glue line of the laminated material showed higher performance compared to those perpendicular to the glue line. The data obtained as a result of this study demonstrated that aramid fiber reinforced Black pine wood laminated materials can be used in the building industry as building materials.

Thermoplastic films for damping laminated materials with improved water resistance

This article covers the development of the thermoplastic extrusion films made of poly(vinyl acetate) (PVA) and poly(butyl methacrylate) (PBMA) for use as an inner layer in metal-polymer-metal multiple-layered vibro-damping materials that can work in contact with water. The effect of the amount of the introduced plasticizer on the dynamic properties of polymer films made of PVA and PBMA is studied on the example of plasticizers from the group of esters of dicarboxylic acids, organic phosphates and chloroparaffins. The processes of water sorption by polymer films and washing out plasticizers from them have been investigated. It has been demonstrated that PBMA-based films containing chlorinated paraffins as a plasticizer have the best water resistance.

Nanometric SiC influence on tribological properties of phenolic composite materials

This paper presents an experimental study of the influence of nano metric silicon carbide in the composition of phenolic composites on the coefficient of friction. The paper is divided into three distinct parts investigating from a tribological point of view three different types of composite materials based on phenolic resin with three concentrations of nSiC (0.5; 1 and 2% by mass). In the first part, a comparative study of the behavior of phenolic resin was performed, representing the basis for the development of composite materials. In the second part, a study was performed on laminated materials reinforced with two-dimensional fabrics (glass fiber and carbon fiber, respectively). The last part studied two types of ablative phenolic materials based on micronic cork, on one hand, and on carbon felt on the other hand.

Mathematical Model of Rotary Machined Helical Surfaces

The rotary cutting method of materials has a number of advantages over the existing traditional cutting methods, e.g. temperature decrease in the cutting zone, also noncumulative blade wear. Due to its high durability, the rotary tool allows processing hardened and difficult-to-machine materials, high-temperature alloys, as well as composite and laminated materials. However, this machining method is usually not applied for machining various shaped surfaces, which is mainly due to the lack of mathematical calculation of the resulting profiles, and the absence of a wide variety of methods for rotary tools installation. The article discusses the mathematical foundation of the resulting profile when processing helical surfaces when processing the flanks of rotary tools.

A cut marker for aircraft seat cover

A cut marker shows how pattern pieces should be cut from one or several layers of fabric and it has a direct impact on fabric consumption. In the confection industry besides clothes, items are made for other purposes. In this paper, an analysis of the making a cut marker for aircraft seat cover is made as well as a description of the materials needed. Aircraft seat cover is made from multilayer (laminated) materials and natural leather. Process of making the cut marker of headrest cover, the backrest cover and the legrest cover is especially considered in this paper. The cost of the material for the production of the aircraft seat cover is calculated with the help of the cut marker. The manufactured aircraft seat cover should be of top quality, which is an imperative today due to the serious competition in the market.