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Being a relatively new process, additive manufacturing needs many studies to be able to produce parts with the required properties. The aim of the paper is to establish whether, based on the physical and mechanical properties determined by tensile testing and by applying finite element analysis (FEA), viable results can be obtained regarding the behavior of the 3D printed structures at the different, static loading. The application of FEA for the tensile testing of 3D specimens led to the results close to those obtained by the tests. The values of the results obtained by simulation are higher by up to 7.2% compared with those recorded by tests. The simulation was applied both for the printed specimens from a single material and from two materials (multi‐material). Regardless of the materials used in printing and the simulation method, the results of applying FEA are close to those recorded by testing. [ABSTRACT FROM AUTHOR]

To effectively utilize a feature set to further improve fault diagnosis of a rolling bearing vibration signal, a method based on multi-fractal detrended fluctuation analysis (MF-DFA) and smooth intrinsic time-scale decomposition (SITD) was proposed. The vibration signal was decomposed into several proper rotation components by applying this new SITD method to overcome noise effects, preserve the effective signal, and improve the signal-to-noise ratio. Wavelet analysis was embedded in iteration procedures of intrinsic time-scale decomposition (ITD). For better results, an adaptive threshold function was used for signal recovery from noisy proper rotation components in the wavelet domain. Additionally, MF-DFA was used to reveal the multi-fractality present in the instantaneous amplitude of the proper rotation components. Finally, linear local tangent space alignment was applied for feature dimension reduction and to obtain fault characteristics of different types, further improving identification accuracy. The performance of the proposed method is determined to be superior to that of the ITD-MF-DFA method. [ABSTRACT FROM AUTHOR]

The paper presents a study concerning the characterisation of EN 1.4136 stainless steel heat-treated by means of concentrated solar energy in orde to improve some mechanical properties. In addition to the standard chemical composition, this steel was alloyed with nickel (Ni 1.5%wt) and copper (Cu 0.30%wt). Nickel was added to increase corrosion strength in acids, oxidising or non-oxidising environments, also facilitating an improved tenacity of the material. The addition of copper allows an increasing atmospheric corrosion strength (for copper content over 0.20%), at the same time intensifying the austenitising effect of nickel. The obtained steel was subjected to a solution heat treatment (hyper-hardening) with a heating time up to a austenitisation temperature (TA = 1050 °C) for 20 (lot A) and for 33 min (lot B), respectively. The maintaining duration for austenitisation was 7 (lot A) and 21 min (lot B), respectively, followed by cooling in water. After the heat treatment in the solar furnace, the specimens were analysed from the structural point of view as well as to their behaviour when subjected to tribological stress, in accordance with the operational requirements for these types of steels. The analysed characteristics were the dynamic friction coefficient (CoF), the wear rates and the hardness (HRC) tests. Based on the collected data, a specific characterisation was made for EN 1.4136 stainless steel heat-treated in a solar furnace. By applying the thermal treatments in the solar furnace, the hardness values have been increased (of about 55%) and the average wear rates have decreased compared to the base material. [ABSTRACT FROM AUTHOR]

Copyright of Romanian Journal of Materials / Revista Romana de Materiale is the property of Foundation for Materials Science & Engineering Serban Solacolu and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The use natural fibres in composites in replacement of mineral-inorganic fillers, is of great interest in the view of the reduction in the use of petroleum-based, nonrenewable resources, and in general in a more intelligent utilization of environmental and financial resources. Material revolution of this century may be provided by green composite materials. Sustainability, design, industrial ecology, eco-efficiency, and green chemistry can form the principles that are guiding the development of a new generation of "green" materials. The paper presents some application devices with green composite sustainable materials for automotive industry. [ABSTRACT FROM AUTHOR]

This study deals with the processing of Cu-TiC-graphite hybrid composites prepared by powder metallurgy route, through mechanical alloying and microwave sintering. Microwave sintering has gained worldwide acceptance as a new method for heating and sintering of a variety of materials as it offers many advantages compared with conventionally sintering like high heating rates, short processing time and lower sintering temperatures with finer microstructure and lower environmental hazards. Green metal based compacts were exposed to high intensity microwave fields and their densification mechanisms, microstructure and mechanical properties were investigated. [ABSTRACT FROM AUTHOR]

This paper deals with the processing, microstructure, mechanical properties and wear behaviour of copper based hybride composites reinforced with TiC and graphite particles. Elemental powders of copper (Cu), titanium carbide (TiC) and graphite (C) were mechanically alloyed in a planetary ball mill, compacted and sintered using spark plasma sintering technique. The addition of alloying elements in the copper have increased the composite hardness. Pin-on-disc was used to evaluate the tribological properties under testing parameters of 12N normal load and 10cm/s sliding speed. The microstructural study revealed that the titanium carbide and graphite particles were uniformly distributed in the matrix phase. [ABSTRACT FROM AUTHOR]

Thermal spraying is the process of applying coatings of high performance materials, such as metals, alloys, ceramics, onto more easily worked and cheaper base materials. Electric arc spray technique is a thermal spray process that uses a direct current electric arc. This work focuses on the microstructural and hardness properties of Ni-2Al claddings deposited on steel, iron and duralumin alloy substrates by using the Electric Arc Thermal Spraying method. The microhardness of the Ni-2Al coatings and of the three substrate materials was measured with a Vickers indenter tester. For microstructural characterization Nikon Eclipse MA100 inverted metallurgical microscope was used. [ABSTRACT FROM AUTHOR]

Flowforming technology has emerged as the most advanced metal forming technique due to its manifold advantages over conventional metal forming techniques such as extrusion and tube drawing. It offers remarkable utilization of metal, high strength high precision rotationally symmetric components with very high specific strength, excellent surface finish and close dimensional tolerances within the envelope of reasonable economics. The process is quite versatile in view of the fact that a great variety of tubular parts, flexibility provided for complicated parts nearer to net shape, can be manufactured with basically the same tooling, enabling customers to optimise designs and reduce weight and cost, all of which are vital. The ever-increasing strength demands of automotive industries, defense and aerospace sectors have given considerable impetus to research work in this area. In this paper, process details of flowforming, the major experimental studies reported in literature have been reviewed. The study brings out the potential and the ever increasing applications of this manufacturing technique in defense, automotive and aerospace sectors. [ABSTRACT FROM AUTHOR]

The present paper aims to be a mathematical modelling and an optimization of resin type composite materials reinforced with Stratimat fiber glass. The modelling and optimization of these composites are based on the results obtain previously from the bending test. There was used Vinalkyd 25 PE-ATA type resin reinforced with Tissue fiber glass with the specific weight of 300 and 500 [g/m²] with 3, 5 and 7 layers and Wire netting 0,8 with the specific weight 400 [g/m²] and a number of 3, 5 and 7 layers. These composites are materials which can be tailored to suit almost in any function in industry and have a very wide spread in many other areas of activity of the most diverse. [ABSTRACT FROM AUTHOR]

Industry presents growing interest in exploitation of advantages provided by foam structure. Solid foam has outstanding low weight as a great part of its volume consists of gas while the rest is of solid material incorporating structural elements. They have high strength and load ability comparing to their small mass/relative density. Solid foams can be used as thermal and sound insulators and energy absorbers as well. Owing to wide variety of applications foreseen and to rising industrial demands research works of foams have got great importance recently. Metal foam production was first realized about the early nineties last century. An example of aluminum foam application is for sound absorption of long tunnels -- being more advantageous than plastic foam used before regarding its fire resistance property as well. Open cell nickel foams have important role by element production using their vast inner surface as catalyst carrier. The first such production plant is already operating in China established by Canadian/Brazilian owners. The paper presents some experimental data for obtaining Al and Ni foams for cars catalyst reactor applications. [ABSTRACT FROM AUTHOR]

In this paper the authors propose to obtain many types of composite materials made from resin reinforced with glass fiber. These materials have been used to manufacture plates. There were obtained 34 types of composite materials for each resin, modifying numbers of layers of insertion (3, 5, 7), types of inserts (stratimat, tissue, wire netting) and specific weight of materials (300, 400, 450, 500 and 600 g/m²). Similar composite materials were used in foundry to manufacture casting patterns [3]. The theme that was chosen for the post-doc project aims to develop the optimum technology and methodology of elaborating materials in order to obtain thin-walled products with enhanced mechanical characteristics so that they are suitable for other domains as well [1]. [ABSTRACT FROM AUTHOR]

Copyright of Metalurgia is the property of Fundatia Metalurgia Romana and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Metalurgia is the property of Fundatia Metalurgia Romana and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Techniques for the preparation of metallic foams, including casting, powder metallurgy and metallic deposition, have been reviewed. There is a present interest in the development of materials capable of plastic deforming to absorb the effects of shock and impact. Solid foams form an important class of lightweight, cellular engineering materials to meet these threats. The foam materials themselves may be divided into two classes according to their morphology. The first group is open cell structured foams containing pores that are connected to each other and form an interconnected network. The second class does not have interconnected pores and is termed as closed cell foams. The paper presents some experimental data for obtaining aluminum foams with hollow pores by casting techniques. The specific equipment used for experiments is also described. [ABSTRACT FROM AUTHOR]

Copyright of Metalurgia is the property of Fundatia Metalurgia Romana and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Metalurgia is the property of Fundatia Metalurgia Romana and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Three‐dimensional (3D) printing processes are nowadays leading the charge in transforming traditional art, engineering, and manufacturing processes. In this study, the structural and thermal behavior of commercially available filaments composed of synthetic poly(acrylonitrile‐co‐butadiene‐co‐styrene) thermoplastic as well as poly(lactic acid) and poly(lactic acid)/polyhydroxyalcanoate reinforced with bamboo (Bambusa sp.) wood flour composite biothermoplastics were assessed by differential scanning calorimetry and infrared spectroscopy, aiming to understand the modifications that occur at the molecular level during their 3D printing. It has been determined that the biothermoplastic materials undergo both molecular reorientations related to tacticity increase and crystallinity decrease when submitted to 3D printing extrusion, while the synthetic thermoplastic undergoes crosslinking due to its butadiene component. All of the studied materials present good water stability (with water uptake values between 0.8% and 24%), and the water absorption follows a pseudo‐Fickian mechanism. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019. [ABSTRACT FROM AUTHOR]

Selective laser technology is an additive technology that can allow for the manufacture of cellular structures using different types of metallic powder with complex applications in industries such as aerospace, automotive and medical implant industries. This paper presents the effect of climate and mechanical stresses on some honeycomb cellular cores, used in sandwich structures made of 316L stainless steel powder by applying the selective laser melting technology. The honeycomb cellular cores have undergone the microhardness testing and the resulting variation obtained from the analyzed samples was 225 ± 15 HV0.3. The compressive strength and the modulus of elasticity of the cellular structures were determined for flatwise and edgewise compressive stresses. Also, the cellular structures were subjected to accelerated corrosion tests in order to determine their mean life in application use conditions similar to those near seas and oceans. Also, a microstructural evaluation of salt deposits was carried out on the cellular structures subjected to accelerated corrosion tests using a salt spray test chamber. [ABSTRACT FROM AUTHOR]