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The cutting process in plasma cutting begins with the formation of a pilot arc between the electrode and the workpiece as a result of the electrical ionization reaction of the highly conductive cutting gas. The gas is heated by the pilot arc until its temperature rises very high then the gas will be ionized and become a conductor of electricity. When the gas stream leaves the nozzle, the gas expands rapidly carrying the molten metal so that the cutting process continues. This plasma temperature can reach 33,000°C, approximately 10 times the temperature produced by the reaction of oxygen and acetylene. If this is related to the mechanical properties of the material, where the material has been heated it will result in changes in the mechanical properties of the material in the heating area/around the cutting plane. Tensile testing is the most widely used type of test because it is able to provide representative information on the mechanical behavior of the material. Seeing an incident like this, it is necessary to test the Effect of Plasma Cutting on the Tensile Strength of 'Fe' Materials through a tensile test. Several studies have shown that torch height, amperage and cutting speed can affect material properties. The best tool parameter settings are obtained at a travel speed of 500 mm/min, 75 amperes and a torch-material distance of 3 mm so that these settings are used as a reference in this study. In analyzing the data, the authors compare the results of plasma cutting testing with conventional cutting, in order to know the changes in mechanical properties that occur.

The fatigue life of drill pipe is a vital factor affecting the drilling process and safety, while severe fatigue failure of drill pipe under the condition of high temperature containing hydrogen sulfide have been reported frequently in recent years. Hence, a systematic methodology was proposed to investigate the fatigue behavior of different drill pipe under multi-factor environment. The present work aims to characterize the fatigue life and mechanism of G105, S135, V150 as well as the titanium alloy drill pipe. The hardness and tensile tests were initially performed to determine the material characterization of the different drill pipe. Then, a fatigue experimental system was specifically designed based on the experimental conditions to evaluate the fatigue property of the drill pipes. Experimental results reveal that in the air, drill pipe’s fatigue life could be longer with the increasing steel grade while in drilling mud, the fatigue performance of titanium alloy drill pipe is the best. The results of sensitivity analysis demonstrate that the coupling factor of H2S mud with temperature showed the greatest influence on the fatigue properties, followed by the single factor of H2S mud and the temperature respectively. The sensitivity to temperature and mud coupling factors is: V150 (65.2%) > S135 (58.1%) > Ti (51.6%) > G105 (40.3%). The sensitivity for H2S mud is: V150 (59.8%) > S135 (51.6%) > G105 (29.7%) > Ti (21.7%). The order of sensitivity to temperature is as follows: Ti (6.5%) > S135 (6.3%) > G105 (2.5%) > V150 (1.5%). The mechanisms underlying fatigue fracture were explored. Finally, according to the experimental results, the economical practicality of different drill pipes is analyzed and compared. The work presented in this paper can provide a technological basis for fatigue theory and service conditions of drill pipes.

To evaluate tensile strength of the carbon composite material we used method of static tensile test according to the STN EN ISO 6892-1:2010-01 standard. The material for the production samples from the composite material was carbon fabrics KORDCARBON 200g/m2 – Twill weave. KORDCARBON 160g/m2 – Plain weave reinforced with epoxy resin Letoxid PR220+hardener EM315. The carbon composite for the test was prepared by Hand lay-up technology and Vacuum Bag molding method. Orientation to the layer laying direction of the individual samples in the test composite material influences the mechanical properties of the carbon fiber composite material produced by Hand lay-up technology and VMB- Vacuum molding bag method.

In this study, we report a method for the repair of damaged SUS 630 parts by directed energy deposition (DED). Herein, we aim to analyze the variations in the mechanical properties of such parts caused by post-repair heat treatment performed to regain the pre-repair mechanical properties. Before repair, substrates were subjected to solution annealing (SA-wrought) or SA treatment followed by precipitation hardening (SA + PH-wrought). Each substrate was repaired using SUS 630 powder. The repaired region was dominated by BCC-structured ferrite (96.7%). It also contained FCC-structured retained austenite (3.3%). The martensite fraction of the samples treated with SA after repair increased by 3.1%. Although BCC remained dominant after the SA + PH post-repair heat treatment, reverted austenite and a large amount of precipitate were generated along the grain boundaries after sufficient aging time of PH treatment. The repaired region displayed lower hardness than the substrate. However, the post-repair heat treatment increased the hardness. Meanwhile, the tensile test results revealed that the tensile strength decreased from that of the wrought material because of the cracks generated at the interface between the repaired region and substrate. Although the tensile strength was improved by SA and SA + PH post-repair heat treatments, the elongation decreased because of the cracks at the interface and reduction in the FCC content of the repaired part. Although cracks occurred at the interface, tensile characteristics almost similar to those of SA-wrought and SA + PH-wrought were observed owing to SA + PH post-repair heat treatment.

The double fabrics having a complex structure are used in different areas both technically and aesthetically. In this study, tensile and air permeability properties of self-stitched double fabrics were investigated. Firstly, six different self-stitched double fabrics having the same yarn type, same settings, two different weave types, and three different stitching arrangements were designed and manufactured. Then, the tensile properties of these double fabrics were tested by applying tensile test at warp and weft directions, and bias-extension test at 45° bias direction. The effect of structural properties on tensile and air permeability results was discussed statistically. The tensile properties of self-stitched double fabrics having plain weave types are mostly better than 2/2 twill ones. The differences between tensile properties of self-stitched double fabrics generally were not found statistically significant according to stitching arrangement except the double fabric having plain weave type and higher stitching points. On the other hand, the differences between air permeability properties of all self-stitched double fabrics were found statistically significant at 95 % confidence level in terms of both stitching arrangement and weave type.

Research on material engineering is widely developed in the precursors, composition of the material, and technique to create a composite. The layering and vacuum infusion resin are the developing technology to create the composites with the new characteristics and properties. This experiment is intended to find out the characteristics of layering carbon fiber reinforced by resin and is molded with vacuum infusion technique. The specimens of this experiment is layered-carbon fiber composites determined in three, four, five, six, and seven layers. The precursors of 220 and 240 carbon fibers are the main material of the composites. The tests conducted to the specimens are bending and tensile tests. The both tests are treated to reveal the mechanical properties of the composites. The least layers of 220 and 240 carbon fiber result the highest value of bending test, but the most number of carbon fiber layers show the opposite value. The results are reverse in the tensile test. The highest value of the tensile test is achieved by the most layers of carbon fiber, while the lowest value is in the least layers. This result is almost the same with the strain-stress, but overall the graphic is similarly increase to the most layers. Deduction achieved in this experiment is that the number of layers in the carbon fiber composites is significantly influencing the mechanical properties of the composite.

The influence of elevated temperatures on mechanical behavior of glued laminated timber beams is examined on the basis of tensile tests. Dog bone samples prepared from beams exposed to fire of variable duration were categorized with respect to the type and position of the failure crack, type and number of discontinuities such as knots, and the level of browning. The acquired experimental results suggest that the wood variability and the effect of growth discontinuities are probably more significant than the effect of elevated temperatures. To support this conclusion, further study is currently under way, exploring samples from the second series of the fire tests.

The waste natural such as groundnut shell, rice husk, eggshell, pistachio shells, etc., are regionally available. All these waste natural has good mechanical characteristics and can be employed more efficiently in the improvement of composite materials for different uses. This paper shows the study of the impact test, tensile test and flexural test properties of the pistachio shell powder strengthened epoxy resin. Pistachio shell powder with different weight fraction (5%, 7%, and 9%) strengthened epoxy resin has been developed by hand lay-up method. The tensile test, flexural test and impact strength displays the sample (epoxy+7% wt. pistachio shells) has the highest comparison with other samples. The principal results extracted from this work that the Samples with (9%) weight fraction of the pistachio shell content in epoxy resin decreases the modulus of elasticity, flexural strength, tensile strength, impact strength and flexural modulus, while at (5% and 7%) weight fraction of the pistachio shell content in epoxy resin raise the modulus of elasticity, tensile strength, flexural modulus, flexural strength and impact strength increased.

In this paper, the design stress intensity values for the plate-type fuel assembly for research reactor are presented. Through a tensile test, the material properties of the cladding (aluminum alloy 6061) and structural material (aluminum alloy 6061-T6), in this case the yield and ultimate tensile strengths, Young’s modulus and the elongation, are measured with the temperatures. The empirical equations of the material properties with respect to the temperature are presented. The cladding undergoes several heat treatments and hardening processes during the fabrication process. Cladding strengths are reduced compared to those of the raw material during annealing. Up to a temperature of 150 °C, the strengths of the cladding do not significantly decrease due to the dislocations generated from the cold work. However, over 150 °C, the mechanical strengths begin to decrease, mainly due to recrystallization, dislocation recovery and precipitate growth. Taking into account the uncertainty of the 95% probability and 95% confidence level, the design stress intensities of the cladding and structural materials are established. The presented design stress intensity values become the basis of the stress design criteria for a safety analysis of plate-type fuels.

Calcium phosphate cements (CPCs) have been widely used during the past decades as biocompatible bone substitution in maxillofacial, oral and orthopedic surgery. CPCs are injectable and are chemically resemblant to the mineral phase of native bone. Nevertheless, their low fracture toughness and high brittleness reduce their clinical applicability to weakly loaded bones. Reinforcement of CPC matrix with polymeric fibers can overcome these mechanical drawbacks and significantly enhance their toughness and strength. Such fiber-reinforced calcium phosphate cements (FRCPCs) have the potential to act as advanced bone substitute in load-bearing anatomical sites. This work achieves integrated experimental and numerical characterization of the mechanical properties of FRCPCs under bending and tensile loading. To this end, a 3-D numerical gradient enhanced damage model combined with a dimensionally-reduced fiber model are employed to develop a computational model for material characterization and to simulate the failure process of fiber-reinforced CPC matrix based on experimental data. In addition, an advanced interfacial constitutive law, derived from micromechanical pull-out tests, is used to represent the interaction between the polymeric fiber and CPC matrix. The presented computational model is successfully validated with the experimental results and offers a firm basis for further investigations on the development of numerical and experimental analysis of fiber-reinforced bone cements.

Nanofibers can be interleaved into polymers and improvements in mechanical properties such as resistance to impact, delamination and debonding as well as enhanced ductility can be obtained. In this work, GFRP laminated composites were interleaved to non-woven nylon 6,6 nanofiber mats which were generated by the electrospinning method. Four kinds of configurations were considered; two pure configurations where GFRP had two and four glass fiber layers and the other two kinds of nanofiber modified configurations that had one and three nylon 6,6 nanofiber mats being interleaved in GFRP. Those specimens were then investigated for their impact resistance, energy absorption and tensile strength capabilities in regard to low-velocity impact and tensile tests. The results showed that adding nylon 6,6 nanofiber mats can increase energy absorption values of the modified specimens, but some decrease in load capacities could be observed.

In this study, a numerical investigation tensile test using ANSYS on three different carbon and alloy sheets of steel: AISI 1030 medium carbon steel, AISI 1080 high carbon steel and high-strength low-alloy (HSLA) A606 steel, has been carried out. The influences of three different specimen geometries on the stress–strain curve were also investigated. Understanding the properties of these materials, such as stress–strain obtained from a tensile test, is important. Materials are subjected to forces or loads when in use, for example, steel in a ship’s hull experiences significant stresses and strains. In such situations, it is necessary to understand the characteristics of the material because grounding or collisions can occur, which deform the materials. The differences in stress and strain obtained from three specimens with different geometries and mesh sizes of 2.5, 5, 7.5, and 10 mm for all proposed steels, were observed. The results showed that the ultimate tensile strength was always lower in specimen 2 compared to the other specimens. Furthermore, the highest von Mises stress and strain contour was located in the midsection of specimens 1 and 3 in all of the proposed materials.

Electropulsing treatment is known to induce the so-called electroplastic effect, which is accompanied by an increase in ductility of metals. However, in this study we find that the application of electric current pulse reduces the flow stress and strain-to-failure in a 316L stainless steel, and it also induces premature fracture with a fracture mode transition from full ductile to partial transgranular cleavage. The results indicate a reverse electroplastic effect, i.e. electropulsing-induced embrittlement. By using transmission electron microscopy (TEM), it is found that the dislocation cell structure became refined, and the density of deformation-induced twins increased as increasing the voltage. The variation of dislocation structure cannot be solely attributed to the heating of sample due to electricity. The embrittlement is believed to be a synthetic effect of Joule heat and electropulsing-enhanced dislocation motion.

Materials science and engineering technology = Materialwissenschaft und Werkstofftechnik 51(4), 432-444 (2020). doi:10.1002/mawe.201900136, Published by Wiley-VCH, Weinheim

In dieser Bachelorarbeit beschäftigt sich der Autor mit der Verwendung von Verbundwerkstoffen in der additiven Fertigung, insbesondere der Nutzung von einem thermoplastischen-Perlitsand-Verbundwerkstoff, der im Rahmen eines Industrieprojektes der FH-Joanneum erstellt wurde. Das Ziel dieser Arbeit ist es, die mechanischen, physikalischen Eigenschaften des thermoplastischen-Perlitsand-Verbundwerkstoffes mit Zugbeanspruchungsversuchen zu ermitteln. Dabei werden die Ergebnisse analysiert und daraus Erkenntnisse ermittelt in Hinsicht auf die Auswirkung der Zusammensetzung von Polylactid und Perlitsand im Verhältnis von 6 und 14% Masseanteil.Um die Forschungsfrage zu beantworten, werden eine Literaturrecherche und praktische Versuche durchgeführt. Dazu werden die Grundbegriffe der additiven Fertigung definiert und von der subtrahierenden Fertigung abgegrenzt. Im weiteren Verlauf werden die Ein-satzgebiete und die Einteilungsformen der additiven Fertigung näher beschrieben. An-schließend wird die Relevanz der Kunststoffe mit den Zusatzstoffen, deren Verarbeitung mittels Extruder näher erläutert und das Potenzial der Verbundwerkstoffe anhand der Faserverbundwerkstoffe dargelegt. Des Weiteren wird die Probenherstellung, die verwendeten Materialien und der Zugbeanspruchungsversuch erörtert. Daraus resultieren die mechanisch, physikalischen Ergebnisse.Durch die Verwendung der mechanischen, physikalischen Ergebnisse wird ein Teilbereich der Erforschung des thermoplastischen-Perlitsand-Verbundwerkstoffes abgedeckt und die Basis für weitere Erforschungen des Materials ergänzt. In this bachelor thesis, the author deals with the use of composite materials in additive manufacturing, in particular the use of a thermoplastic perlite sand composite material, which was created as part of an industrial project at the FH-Joanneum. The aim of this work is to determine the mechanical, physical properties of the thermoplastic perlite sand composite material with tensile stress tests. The results are analysed, and findings are de-termined regarding the effect of the composition of polylactide and pearlite sand in the ratio of 6 and 14% by mass.To answer the research question, a literature review and practical tests are carried out. For this purpose, the basic terms of additive manufacturing are defined and distinguished from subtractive manufacturing. In the following, the areas of application and the classification forms of additive manufacturing are described in more detail. Subsequently, the relevance of plastics with additives and their processing by means of extruders is explained in more detail, and the potential of composite materials is presented based on fibre composites. Fur-thermore, the sample production, the materials used, and the tensile stress test are dis-cussed. This results in the mechanical, physical outcomes.By using the mechanical, physical results, a sub-area of research into the thermoplastic per-lite sand composite material is covered and the basis for further research into the material is supplemented. Verfasser: Daniel Dupke Abweichender Titel laut Übersetzung der Verfasserin/des Verfassers Bachelorarbeit FH JOANNEUM 2022

In the silicone material extrusion (MEX) process, product profile error and performance defects are common problems due to changes in strand shape. A process optimization method considering strand morphology, denoted as SMO, which allows adjustment of the strand shape by adjusting process parameters during the printing process is presented. The relation between process parameters (extrusion speed, moving speed, nozzle height, and nozzle radius) and the geometric parameters (strand width and strand height) of the cross-section, as well as the relationship between strand spacing, layer height, and process parameters in no void constraint is discussed and verified. SMO was utilized to produce specimens with tunable strand width and strand height. Tensile tests and profile scans were performed to compare SMO with other methods to verify its feasibility. Specimens fabricated using the SMO method have up to a 7% increase in tensile strength, up to a 10% reduction in processing time, and about a 60% reduction in strand height error over unused ones. The results show that the SMO method with adjustable strand width can effectively balance efficiency and mechanical properties compared to uniform infill, and the SMO method with adjustable strand height can provide higher accuracy compared to uniform strand height. The proposed method is validated and improves the efficiency and accuracy of silicone MEX.

Unfolding the structure–property linkages between the mechanical performance and microstructural characteristics could be an attractive pathway to develop new single- and polycrystalline Al-based alloys to achieve ambitious high strength and fuel economy goals. A lot of polycrystalline as-cast Al-Cu-Mg-Ag alloy systems fabricated by conventional casting techniques have been reported to date. However, no one has reported a comparison of mechanical and microstructural properties that simultaneously incorporates the effects of both alloy chemistry and mechanical testing environments for the as-cast Al-Cu-Mg-Ag alloy systems. This preliminary prospective paper presents the examined experimental results of two alloys (denoted Alloy 1 and Alloy 2), with constant Cu content of ~3 wt.%, Cu/Mg ratios of 12.60 and 6.30, and a constant Ag of 0.65 wt.%, and correlates the synergistic comparison of mechanical properties at room and elevated temperatures. According to experimental results, the effect of the precipitation state and the mechanical properties showed strong dependence on the composition and testing environments for peak-aged, heat-treated specimens. In the room-temperature mechanical testing scenario, the higher Cu/Mg ratio alloy with Mg content of 0.23 wt.% (Alloy 1) possessed higher ultimate tensile strength when compared to the low Cu/Mg ratio with Mg content of 0.47 wt.% (Alloy 2). From phase constitution analysis, it is inferred that the increase in strength for Alloy 1 under room-temperature tensile testing is mainly ascribable to the small grain size and fine and uniform distribution of θ precipitates, which provided a barrier to slip by deaccelerating the dislocation movement in the room-temperature environment. Meanwhile, Alloy 2 showed significantly less degradation of mechanical strength under high-temperature tensile testing. Indeed, in most cases, low Cu/Mg ratios had a strong influence on the copious precipitation of thermally stable omega phase, which is known to be a major strengthening phase at elevated temperatures in the Al-Cu-Mg-Ag alloying system. Consequently, it is rationally suggested that in the high-temperature testing scenario, the improvement in mechanical and/or thermal stability in the case of the Alloy 2 specimen was mainly due to its compositional design.

The steel–plastic compound geogrid has been widely used as a new reinforcement material in geotechnical engineering and other fields. Therefore, it is essential to fully understand the mechanical properties of steel–plastic compound geogrid-reinforced belts to utilize steel–plastic compound geogrids efficiently. In this study, tensile mechanical tests of steel wire, polyethylene geogrid belt, and steel–plastic compound geogrid-reinforced belt were conducted with respect to the tensile mechanical properties of steel–plastic compound geogrid-reinforced belts. In addition, the minimum reinforcement and optimal reinforcement ratios of steel–plastic compound geogrid-reinforced belts were summarized. The results showed that the steel–plastic compound geogrid-reinforced belts possessed an incongruent force of the internal steel wire during the tensile process. The tensile stress–strain curve of the steel–plastic compound geogrid-reinforced belt can be divided into the composite adjustment, steel wire breaking, and residual deformation stages. The tensile strength of the steel–plastic compound geogrid-reinforced belt is proportional to the diameter and number of steel wires in the reinforced belt. The minimum and optimum reinforcement ratios of steel wire in the steel–plastic compound geogrid-reinforced belt were 0.63% and 11.92%, respectively.

With an aim to develop a good coil winding insulation film, fillers of boehmite alumina in the shape of a roughly rectangular plate were added with ratios of 10 and 20 wt% to polyimide. The filler surface was untreated or treated with a methacrylic or an epoxy silane coupling agent. Such prepared polyimide nanocomposites were subjected to various tests to measure the tensile strength, elastic modulus, complex permittivity, and thermal conductivity. It was found that samples with fillers treated using the methacrylic silane coupling agent have the strongest adhesion at the filler/polyimide interfaces and the lowest dielectric loss factor at high temperatures. A positive relationship between the filler/polyimide adhesion and the thermal conductivity is also indicated. These findings are significant since they indicate that the adhesion status at the filler/polymer interface exerts a strong influence on the thermal and electrical conduction processes in the polymer.

In the present work, dissimilar butt joints between a low-Ni, medium-Mn austenitic stainless steel, M-Mn SS, and a Ni-Cr austenitic stainless steel, Ni-Cr SS, were processed by utilizing the gas tungsten arc welding (GTAW) technique at different heat inputs. A filler metal of ER308 was employed in the welding process. The filler yields 480 MPa, which is equivalent to the yield strength of M-Mn SS. The microstructural analysis and mechanical performance (i.e., tensile strength and hardness properties) of the concerned joints were studied by using an optical microscope and uniaxial tensile tests, respectively. The results revealed that a duplex structure from austenite matrix and delta ferrite is promoted in the fusion zone (FZ) of the dissimilar joints processed with low and high energy inputs (0.486 kJ/mm and 0.558 kJ/mm). The FZ of the specimens welded at high heat input exhibited the lowest hardness value (151.2 HV) in comparison to heat affected zone (HAZ) (166.3 HV). Moreover, the joints exhibited a low tensile strength of 610 MPa. The achieved strength is significantly lower than the strengths of the base metals (BMs) M-Mn SS and Ni-Cr SS. This is mainly attributed to the inhomogeneous dendritic structure of the FZ with Cr-carbides precipitation.

This paper presents an optimized washing protocol for as-received natural fibers, prior to large-scale composite manufacturing, for the structural strengthening of historic masonry. The aim was to achieve a simple protocol for standard cleaning of fiber surfaces from low molecular weight constituents that may be detrimental towards interfacial strength without damaging the fibers. The proposed procedure employs the application of the solvent sequence: ethanol, acetone, hexane, with optimized incubation times and stirring conditions. Additionally, this procedure may change the surface of the fiber, thereby enhancing the durability of the fiber-matrix interface. The washing protocol resulted in an increase of tensile strength by 56%, 52% and 22% for flax, hemp and sisal fibers, respectively, as compared to the corresponding non-washed fibers, without loss of elongation. The static contact angle measurements confirmed exposure of a higher fraction of the hydrophilic crystalline cellulose, with a higher wettability observed after washing protocols., This work was partly financed by the Portuguese Foundation for Science and Technology (FCT/MCTES) through national funds (PIDDAC) under the R&D Unit Institute for Sustainability and Innovation in Structural Engineering (ISISE) under reference UIDB/04029/2020. IPC acknowledges the support of FCT through National Funds References UIDB/05256/2020 and UIDP/05256/2020. The authors wish to acknowledge FCT for the PhD scholarship granted to the first author (SFRH/BD/144106/2019).

Dissimilar Ti–Al laser weldings are very interesting due to their difficulties in being processed because of the different physical properties of the alloys and the crack formations during cooling and solidification. In this study, the effect of laser offset and defocusing on microstructure, geometry and mechanical properties response of 2 mm thick dissimilar AA6061/Ti-6Al-4V laser welds was analyzed. Moreover, in order to reduce residual stresses, the joints were both heat-treated and mechanically treated by ultrasonic peening. The welds microstructure was found to be martensitic in the Ti-6Al-4V fusion zone, columnar dendritic in the AA6061 fusion zone and partially martensitic in the Ti-6Al-4V heat-affected zone. Intermetallic compounds based on the Al–Ti system were detected at the AA6061/Ti-6Al-4V interface and in the aluminum fusion zone. Both negative defocusing and higher laser offset improved the tensile performance of the welds, mainly by reducing the amount of brittle intermetallic compounds. The stress relaxation heat treatment, leading to the aging of the martensite and the increasing of the size of the intermetallic compound, reduced the tensile strength and ductility of the joints. On the contrary, for dissimilar Al–Ti welds, mechanical treatment was effective in increasing joints ductility and, moreover, corrosion resistance.

This study takes large size samples after hot-upsetting as research objects and aims to investigate the optimization double-stage annealing parameters for improving the mechanical properties of hot-upsetting samples. The double-stage annealing treatments and uniaxial tensile tests for hot-upsetting GH4169 superalloy were finished firstly. Then, the fracture mode was also studied. The results show that the strength of hot-upsetting GH4169 superalloy can be improved by the double-stage annealing treatment, but the effect of annealing parameters on the elongation of GH4169 alloy at high temperature and room temperature is not significant. The fracture mode of annealed samples at high-temperature and room-temperature tensile tests is a mixture of shear fracture and quasi-cleavage fracture while that of hot-upsetting sample is a shear fracture. The macroscopic expressions for the two fracture modes belong to ductile fracture. Moreover, it is also found that the improvement of strength by the double-stage annealing treatment is greater than the single-stage annealing treatment. This is because the homogeneity of grains plays an important role in the improvement of strength for GH4169 superalloy when the average grain size is similar. Based on a comprehensive consideration, the optimal annealing route is determined as 900 °C × 9–12 h(water cooling) + 980 °C × 60 min(water cooling).

The stress distribution in specimens designed for the tensile testing is evaluated in the article. The reinforcement consists of long fibers that copy the outer contour of the specimen. The fibers are inserted within the curvature at the edge of the specimen with the neck. The stress distribution in fibers and matrix of dogbone specimen and specimen of rectangular shape is analyzed and compared. The analysis of stress state is analyzed in FEM software ADINA. Long fibers deposited in specimen were modeled using rebar elements.

Continuous fiber fabrication technology, developed by Markforged and used in MarkTwo printers, allows using of reinforcing fibers, which improve mechanical properties of produced parts. The technology enables choosing of two fiber deposition strategies: isotropic fiber fill and concentric fiber fill. With the isotropic fiber fill, there is an option to set up various fiber angles in each layer. The article is focused on stress distribution analysis using FEM in a matrix and individual reinforcing fibers of specimens loaded to uniaxial tension. Main observed parameters are stresses in matrix and fiber and usage of the reinforcing material.

For metallic materials, standard uniaxial tensile tests with round bar specimens or flat specimens only provide accurate equivalent stress–strain curve before diffuse necking. However, for numerical modelling of problems where very large strains occur, such as plastic forming and ductile damage and fracture, understanding the post‐necking strain hardening behaviour is necessary. Also, welding is a highly complex metallurgical process, and therefore, weldments are susceptible to material discontinuities, flaws, and residual stresses. It becomes even more important to characterize the equivalent stress–strain curve in large strains of each material zone in weldments properly for structural integrity assessment. The aim of this paper is to provide a state‐of‐the‐art review on quasi‐static standard tensile test for stress–strain curves measurement of metallic materials. Meanwhile, methods available in literature for characterization of the equivalent stress–strain curve in the post‐necking regime are introduced. Novel methods with axisymmetric notched round bar specimens for accurately capturing the equivalent stress–strain curve of each material zone in weldment are presented as well. Advantages and limitations of these methods are briefly discussed. © 2019 The Authors. Fatigue & Fracture of Engineering Materials & Structures published by John Wiley & Sons Ltd This is an open access article under the terms of the Creative Commons Attribution License

This paper introduces a new method for the characterisation of the boundary of diffuse and local necking based on DIC measurements during tensile tests. A series of images illustrate the extension of diffuse necking and show the occurrence of local necking as well. The evaluation of strain distribution gives the exact description of processes using both time dependent and non-dependent methods.

During the last decades, widespread seismic events in the Southern European zone have significantly damaged the masonry built heritage. Designers and researchers studied different techniques to increase the performance of masonry panels subjected to horizontal actions due to seismic phenomena. In particular, two of the most common strengthening systems are Fiber Reinforced Cementitious Matrix (FRCM) and Composite Reinforced Mortar (CRM). These systems are usually applied on both surfaces of the load-bearing elements in order to increase their shear strength properties. This work aims at analyzing the effects of three different matrices, comparing FRCM and CRM systems applied on double-leaf masonry panels subjected to diagonal compression test in displacement control (ASTM E519). Compressive strength and thickness of the matrices applied on the masonry substrate were investigated in order to evaluate the relationship between the performance of matrices used within composite strengthening systems (FRCM or CRM) and the density of fiber grids adopted (basalt and glass). The mechanical characterization of the different strengthening systems was performed by means of tensile and bond tests on masonry prisms. Finally, the experimental results obtained were analyzed in terms of failure modes and maximum capacity attained by strengthened panels.

Son yıllarda, eklemeli imalat sektörüve teknolojisinin ilgisine ve önemine paralel olarak, üç boyutlu (3B) parçaüretimi için kullanılan fotokürlenebilir polimer reçineler üzerine yapılançalışmalar büyük ilgi görmektedir. Eklemeli imalat yöntemlerinden biri olanStreolitografi (SLA) yöntemi, yüksek hızlı işleme ve parça üretimi hassasiyetiaçısından diğer yöntemlerden ayrılmasının yanı sıra mekanik ve diğerkarakteristik özelliklerinin değiştirilmesine izin vermektedir. Özelliklepolimer kompozit malzemelerin mekanik dayanımını arttırmak için birçok çalışmagünümüze kadar yapılmaktadır. Kil, Al2O3, SiO2,BaTiO3, ZrO2 gibi seramik malzemeler mekanik dayanımıartırmak için takviye malzemesi olarak örnek verilebilir. Bu çalışmada, dört farklı (katkısız, %0,25,%0,5, %1) konsantrasyona sahip füme silika katkılı polyester esaslı akrilatfotokürlenebilir reçinenin mekanik özelliklerine etkisi araştırılmıştır. 167m2/gryüzey alanına sahip füme silika %0,25, %0,5 ve %1 konsantrasyonlarındafotokürlenebilir reçineye eklenmiştir. Çekme testi, dinamik mekanik analiz(DMA) ve taramalı elektron mikroskobu (SEM) sonuçlarına göre, SLAkompozitlerinin artan füme silika konsantrasyonu ile birlikte mekanikdayanımının artmasına rağmen termal kararlılığında azalma (depolama ve kayıp modülü) görülmüştür. Fümesilikanın yüksek yüzey alanı nedeniyle, fotokürlenebilir reçine içerisinde %1konsantrasyonuna kadar nispeten daha iyi homojen dağıldığı olduğugözlemlenmiştir., In recent years, parallel to the interest andimportance of additive manufacturing sector and technology, the studies on photo-curable polymer resins which will be used forthe production of 3-D parts have attracted great interest in recent years.Streolithography (SLA) method, which is one of the additive manufacturingmethods, is distinguished from other methods in terms of highspeed machining and part production precision. Moreover, it allows for theproduction of functional polymeric structures by enhancing their mechanical,thermal, electrical properties, etc… In particular, it has been known thatstudies to increase the mechanical strength of polymer composite materials arevery common. Ceramic materials such as clay, Al2O3, SiO2,BaTiO3, ZrO2, etc are used as reinforcing materials for mechanicalstrength. In this study, the improvement of mechanical properties of polyesterbased acrylate photo-curable resin by reinforcement with fumed silica fillerswere investigated. Fumed silica with 167m2/gr surface was added intophoto-curable resin at three different (%0,25, %0,5 and %1) concentration.According to the tensile test, dynamic mechanical analyzer (DMA) and scanningelectron microscope (SEM) observation, even though mechanical propertiesenhances, thermal stability (storage and loss modulus) values of SLA compositesare decreased as increasing amount of fumed silica. Due to its high surfacearea of reinforcement agent, it is clearly seen that fumed silica completelydispersed in the photo-curable resin up to %1 fumed silica concenration.

Objectives: The aim is to compare the adhesion between zirconia and cements attained with melt-etching with potassium hydrogen difluoride, KHF2, with that found when such traditional surface treatments as sandblasting and ceramic stone grinding are employed. Materials and methods: Groups of zirconia crowns where treated by sandblasting (n = 6), grinding with carbide bur (n = 6) or melt-etching with KHF2 (n = 6) of the surface before cementation with a resin cement to an implant substitute made by Selective Laser Melting of a cobalt-chromium alloy. Tensile testing was performed to rupture, while measured increasing load at the zirconia-cement interface. The strength was calculated by dividing the rupture load with the contact area. The three groups were compared using one-way ANOVA. Results: The adhesion strength between the zirconia crowns and the cement resulted in significant differences between all groups (p

The article presents an experimental study of mechanical properties of cellulose biofilm produced by bacterial fermentation process. Naturally derived biomaterial has great current and potential applications therefore the conditions of material preparation as well as control and prediction of mechanical properties is still a relevant issue. Bacterial cellulose was obtained as a secondary product from Kombucha drink. Presented technique for material preparation and drying is particularly simple and easy to access. The influence of drying temperature (25 °C, 50 °C and 75 °C) on the sample size (thickness and planar dimensions) and mechanical properties (tensile and bursting strength) of cellulose biofilm has been evaluated. It was estimated that during drying biofilm specimens lost up to 92 % of weight and up to 87 % of thickness therefore planar specimen dimensions varied insignificantly. The study showed that the drying temperature is important for optimum strength properties of bacterial cellulose biofilm. The maximum tensile strength (27.91 MPa) was recorded for the samples dried at temperature of 25 °C, when the moisture from the biomaterial is removed gradually and good deformation properties are ensured (respectively tensile extension 18.8 %). Under higher drying temperature biomaterial shows lower values of tensile strength and higher values of bursting strength. The maximum bursting strength (57.2 MPa) was recorded for samples dried at 75 °C when punch displacement changes were insignificant for all tested samples (from 17.8 mm to 21.7 mm). DOI: http://dx.doi.org/10.5755/j01.ms.25.3.20764

Welding is a technique of fusion joining the material involving a process of inter-molecular diffusion adhesion. Polymer welding is an assembly method among several known assembly techniques such as gluing. This welding process applies to thermoplastics; they have the rheological or softening characteristics during melting. This process is fast and controlled in order to obtain a solid and durable mechanical connection on the series parts. This study focuses on the weldability of high density polyethylene (HDPE) using the friction stir welding technique. A parametric choice was made to optimize the operating parameters namely the shape of the welding tool, the speed of rotation and the speed of advance of the tool. Monotonic tensile tests were used to compare the mechanical characteristics between a HDPE test specimen and a specimen taken from an FSW weldment. It emerges from this study that the FSW welding introduces a weakening of the joints characterized by a clear decrease of the deformation at break.

Utilization of advanced engineering thermoplastic materials in fused filament fabrication (FFF) 3D printing process is critical in expanding additive manufacturing (AM) applications. Polypropylene (PP) is a widely used thermoplastic material, while silicon dioxide (SiO2) nanoparticles (NPs), which can be found in many living organisms, are commonly employed as fillers in polymers to improve their mechanical properties and processability. In this work, PP/SiO2 nanocomposite filaments at various concentrations were developed following a melt mixing extrusion process, and used for FFF 3D printing of specimens’ characterization according to international standards. Tensile, flexural, impact, microhardness, and dynamic mechanical analysis (DMA) tests were conducted to determine the effect of the nanofiller loading on the mechanical and viscoelastic properties of the polymer matrix. Scanning electron microscopy (SEM), Raman spectroscopy and atomic force microscopy (AFM) were performed for microstructural analysis, and finally melt flow index (MFI) tests were conducted to assess the melt rheological properties. An improvement in the mechanical performance was observed for silica loading up to 2.0 wt.%, while 4.0 wt.% was a potential threshold revealing processability challenges. Overall, PP/SiO2 nanocomposites could be ideal candidates for advanced 3D printing engineering applications towards structural plastic components with enhanced mechanical performance.

形態: カラー図版あり, Physical characteristics: Original contains color illustrations, Accepted: 2021-03-04, 資料番号: PA2120054000

Tungsten carbide-cobalt (WC-Co) alloys have various mechanical properties according to their Co content and manufacturing method. High-strength materials such as WC-Co alloys are usually manufactured using various sintering methods. In this study, WC-Co was compared according to the Co content and manufacturing method using the sinter-hot isostatic pressing process. Furthermore, an additional test was performed to investigate the effect of post-hot isostatic pressing (HIP) treatment on the mechanical properties. To compare tensile strength, threaded end and shoulder end specimens are generally applied in axial tensile testing with hard metals. However, it is extremely difficult to shape WC-Co by machining. A tensile testing jig for a shoulder end specimen is, therefore, proposed. Tensile tests were conducted using the proposed jig, and microstructure, hardness, and impact tests were carried out to compare the mechanical properties. The microstructure evolution was obtained by decreasing the Co content and applying the HIP treatment, resulting in changes in Young’s modulus and strength. The results indicated that the proposed jig of the axial tensile test could be applied to the extremely hard WC-Co, and the mechanical properties of WC-Co could be modified by the Co content and HIP treatment control.

The structural, physical, and mechanical properties of aluminium after laser-induced shock peening (LSP) were investigated before and after depositing films of various metals (Cu, In, and Al). The deposition of single and double films was conducted, and the physical property (density), shockwave properties (shock pressure, particle velocity, and shock velocity), mechanical properties (stress, strain, Young's s modulus, and Hardness) were calculated, Young's s modulus measured of aluminum was measured by classical method (Tensile test) and by LSP technique, and it was found that the measured using LSP is closer to the standard value than classical method. Single film Cu and sandwich Al / Cu deposited on Al substrate showed an enhancement in the mechanical properties rather than other films, while the deposited films of (In, In / Cu, and Al /In) on Al substrate revealed more strain and higher ductility than others. The laser-induced shock wave has a great importance in viruses, industrial and medical applications.

The effect of off-axis ply on the tensile properties of unbalanced symmetric [0/θ]ns laminates was explored through experimental and numerical analysis. Six CFRP [0/θ]2s plies with different off-axis angles θ were fabricated for tensile tests. In situ observations of the damage to the laminates were conducted to investigate the initiation and progressive growth of the laminates during the tension tests. The fiber fractures, crack initiation, and progressive propagation were analyzed by observing the free edge of the laminates, and the difference in damage behavior caused by different off-axis angles was investigated. All the six [0/θ]2s plies with off-axis angles θ ranging from 15° to 90° showed approximate linear stress–strain responses in the tensile tests. Matrix cracks were not observed prior to the final catastrophic failure in the off-axis layers of the [0/θ]2s laminates with a θ in the range of 15–60°. Finite element analysis (FEA) of the [0/θ]s plies was conducted using a 3D micromechanical model, in which matrix cracking and fiber-matrix debonding in the off-axis layer were simulated using a cohesive interface element. Three micromechanical crack-free, cohesive interface, and initial crack models were analyzed to predict the influence of the matrix cracks inside the off-axis layer on the damage behavior of the [0/θ]s laminates. The numerical results from the initial crack micromechanical model show a lower bound of the tensile strength of the [0/θ]s plies. A high stress concentration is observed adjacent to the cracked off-axis layer, inducing a tensile strength loss of about 20%.

Polypropylene (PP) is an engineered thermoplastic polymer widely used in various applications. This work aims to enhance the properties of PP with the introduction of titanium dioxide (TiO2) nanoparticles (NPs) as nanofillers. Novel nanocomposite filaments were produced at 0.5, 1, 2, and 4 wt.% filler concentrations, following a melt mixing extrusion process. These filaments were then fed to a commercially available fused filament fabrication (FFF) 3D printer for the preparation of specimens, to be assessed for their mechanical, viscoelastic, physicochemical, and fractographic properties, according to international standards. Tensile, flexural, impact, and microhardness tests, as well as dynamic mechanical analysis (DMA), Raman, scanning electron microscopy (SEM), melt flow volume index (MVR), and atomic force microscopy (AFM), were conducted, to fully characterize the filler concentration effect on the 3D printed nanocomposite material properties. The results revealed an improvement in the nanocomposites properties, with the increase of the filler amount, while the microstructural effect and processability of the material was not significantly affected, which is important for the possible industrialization of the reported protocol. This work showed that PP/TiO2 can be a novel nanocomposite system in AM applications that the polymer industry can benefit from.