Effect of microstructure on mechanical properties and abrasive wear behavior of low carbon dual-phase steels

The mechanical properties and wear behavior of Dual Phase (DP) steels have been investigated and compared with those observed in normalized (N) steel that has the same chemical composition. The DP steels having different content and morphology of martensite were produced by varying intercritical annealing temperature and initial microstructures. Mechanical properties of four different DP steels and N steel have been investigated by carrying out tensile and macrohardness tests. Dry sliding wear tests have been conducted on four different the DP steels and the N steel using pin-on-plate to investigate their wear characteristics. It has been found that the yield and tensile strengths and macrohardness increase with increasing martensite content and decreasing martensite size. The yield and tensile strengths and macrohardness of the N steel were significantly lower than the DP steels whereas percentage of total elongation was higher. Wear properties are improved by increasing martensite volume fraction and size in the DP steels. The N steel specimen showed the highest wear rate

Analytical and numerical ınvestigation of the tensile strength of hybrid composites created with glass and carbon fibers

Kompozitlerin kullanım alanları arttıkça farklı tip elyafların birlikte kullanıldığı karma kompozitlerin de kullanım alanları genişlemektedir. Karma kompozitler, dayanım ve maliyet birlikte düşünüldüğünde ümit verici bir yaklaşım getirmektedir. Bu çalışmada çeşitli dizilimlerle oluşturulan cam/karbon elyaf karma kompozitlerin çekme ve moment yükü altında dayanımları analitik ve nümerik olarak incelenmiştir. Ayrıca yalın cam elyaf ve yalın karbon elyaftan oluşan kompozitler de karşılaştırma açısından sonlu elemanlar analizine tabii tutulmuştur. Bu kompozitler üzerine gelen yüke karşılık dayanımları klasik tabaka teorisi kullanılarak analitik yaklaşım ile de çözülerek sonlu elemanlar analizleri doğrulanmıştır. Yapılan analizler sonucunda kullanılan elyafın çekme dayanımına doğrudan etkisinin olduğu, katman diziliminin ise etkisinin olmadığı sonucuna varılmıştır. Moment yükü altında ise en yüksek çekme yüküne maruz kalan en alt katmanda karbon elyaf kullanımının cam elyafa göre dayanabileceği en yüksek moment yükünü yaklaşık olarak %33 arttırdığı görülmüştür. Aynı yük altında diğer katmanlarda kullanılan elyafın etkisinin ise çok sınırlı kaldığı sonucuna varılmıştır.As the usage areas of composites increase, the usage areas of hybrid composites in which different types of fibers are used together are also expanding. Hybrid composites offer a promising approach when strength and cost are considered together. In this study, the strengths of glass/carbon fiber composites formed with various stacking sequences under tensile and moment load were investigated analytically and numerically. In addition, composites consisting of pure glass fiber and pure carbon fiber were also subjected to finite element analysis for comparison. The finite element analysis was verified by using the classical lamination theory to solve the strengths of these composites against the load with an analytical approach. As a result of the analysis, it was concluded that the fiber used has a direct effect on the tensile strength, but the stacking sequence has no effect. Under the moment load, it was observed that the use of carbon fiber in the bottom layer, which is exposed to the highest tensile load, increases the highest moment load that it can withstand by approximately 33% compared to glass fiber. Under the moment load, it was observed that the use of carbon fiber in the bottom layer, which is exposed to the highest tensile load, increases the highest moment load that it can withstand by approximately 33% compared to glass fiber. It was concluded that the effect of the fiber used in the other layers under the same load was very limited

Design and analysis of lightweight automotive component for turbocharger units

Nowadays global warming in parallel with air pollution is a significant problem. One of the major causes is the conventional fuel-powered automobile. This study focuses on reducing global warming caused by automobiles. This paper presents the results of redesign and analysis of piping component of a turbocharger unit from a new material in order to reduce the weight and unify the component from only one material. The existing component is composed of three different parts and materials. With the new design, in addition to the lightweight property, the component is designed in such a way that two separate parts of existing design are unified in a single part which simplifies the assembly of the component to the turbocharger unit. The design starts with choosing the convenient material to satisfy the necessary service conditions such as high temperature and pressure. Two different materials are considered for the analyses which are aluminium alloy and PA66+PA6-HI glass fiber reinforced plastic matrix composite material. Firstly, finite element analyses were performed by using a commercial software. The results of the finite element analyses showed that both materials showed resistance to tensile load of 4000 N and pressure of 0.4 MPa at 22°C. However, if two separate parts were unified with a single part made of aluminium alloy, this component would fail under pressure of 0.4 MPa at 150°C and 210°C, while the component made of PA66+PA6-HI glass fiber reinforced plastic matrix composite material resisted the pressure at higher temperatures. Tensile tests under 4000 N and pressure tests under 0.4 MPa at temperatures of 22°C, 150°C and 210°C were carried out on the component produced by PA66+PA6-HI glass fiber reinforced plastic matrix composite material. The same results were observed with those obtained by the finite element analyses. The design with the composite material satisfies both the mechanical and lightweight considerations.This work is supported by TUBITAK-Turkish Scientific and Technological Research Council under the project number: 7130723

Mechanıcal Propertıes And Faılure Analysıs Of Bolted Joınts Carbon/Epoxy Nanocomposıtes Lamınates Enhanced Wıth Carbon Nanotube And Nanoclay

Nanopartikül katkısı genellikle kompozit malzemelerin özelliklerini geliştirmede oldukça etkili olarak nitelendirilir. Ancak literatürde özellikle cıvata bağlantılı kompozit malzemelerde etkisi incelenmemiştir. Aynı zamanda, ayrı ayrı karbon nanotüp (KNT) ve nanokilin belirli oranlarda katıldığında kompozitin mekanik özelliklerini arttırdığı bilinse de birlikte kullanıldığı zaman nasıl bir davranış sergileyeceği de önemli bir noktadır. Bu çalışmada nanopartikül katkısının cıvata bağlantılı nanokompozitlerin mekanik özelliklerine etkisi incelenmiştir. Fiber olarak karbon, matris olarak epoksi katkı maddesi olarak da KNT ve nanokil kullanılmıştır. Numuneler vakum infüzyon yöntemi ile üretilmiştir. Nanopartiküllerin matris içerisinde homojen olarak dağıtılması için uçlu sonikasyon yöntemi kullanılmıştır. Üretilen numunelere yakma, eğme, çekme ve cıvatalı çekme testleri uygulanmıştır. Nanopartikül katkısı arttıkça fiber hacim oranının azaldığı boşluk hacim oranın ise arttığı saptanmıştır. Numunelere eğme ve eksenel çekme yükleri uygulanarak hasar analizleri yapılmıştır. Genel olarak nanopartikül katkısının mekanik özelliklere etkisi olumlu olmuştur. Eğme mukavemeti için en iyi sonuç %0,3 karbon nanotüp katkılı KNT3 numunelerden, çekme mukavemeti için en iyi sonuç hibrit katkılı numunelerden elde edilmiştir. Ayrıca cıvatalı çekme deneyi ile eksenel yük altında yatak mukavemetleri incelenmiştir. En yüksek yatak mukavemeti %4 nanokil katkılı numunede elde edilmiştir. Bu numunelerde nanopartikül katkısı ile elastiklik modülü ve tokluk genellikle artmıştır. Nanopartikül katkısız, nanokil katkılı NK4, KNT katkılı KNT3 ve hibrit numunelerinin SEM görüntüleri de incelenerek deney sonuçlarıyla birlikte yorumlanmıştır.In general, reinforcement of nanoparticles to composite materials are considered to be highly effective to improve their properties. However especially the effect of nanoparticles on bolted joints nanocomposite structure have not been studied in the literature. Although it is known that, carbon nanotube (CNT) and nanoclay improve mechanical properties of nanocomposites when they are added separately it is very important point to reveal the fact how composites react if both CNT and nanoclay added together. In this study, the effect of nanoparticles on mechanical properties of bolted joints carbon/epoxy nanocomposite structures was studied. Carbon was used as fiber, epoxy was used as matrix, CNT and nanoclay was used as reinforcement. Vacuum assisted resin transfer molding (VARTM) method was used to manufacture the composite materials. Probe sonicator was used to distribute the nanoparticles in matrix homogeneously. Burning, three points bending and tensile test were performed on the samples. It has been observed that porosity volume fraction increased with increasing the amount of nanoparticles. Bending and tensile load were applied to samples in order to perform failure analysis. The nanoparticles show beneficial effect on mechanical properties in general. Of the all samples, the reinforced with 0,3% carbon nanotube, KNT3, and the hybrid sample showed the highest bending and tensile strength respectively. Bearing strength of bolted joints carbon/epoxy nanocomposites also have been studied by using tensile test. It was found, reinforced with 4% nanoclay, NK4, showed the highest bearing strength. Modulus of elasticity and thoughness values increased with reinforcement nanoparticle. Fractography of nanoparticules-free, nanoclay enhanced, CNT enhanced and hybrid samples were were performed by using scanning electron microscope (SEM)

Enhancing mechanical properties of bolted carbon/epoxy nanocomposites with carbon nanotube, nanoclay, and hybrid loading

The effects of adding nanoclay (NC), carbon nanotube (CNT), and a hybrid of both on bending, tensile and bearing strengths of nanocomposite plates were investigated in this study. Sonication method was used to ensure dispersion of the nanoparticles in epoxy homogeneously. The nanocomposite plates were produced by a vacuum assisted resin transfer molding (VARTM) process. Mechanical properties were investigated by applying bending and tensile testing as well as tensile test with bolted joints on the nanocomposite plates. According to the bearing strength, 5.2%, 3.9%, and 0.8% improvements were obtained in NC, CNT and hybrid (NC + CNT) loaded specimens respectively while much more improvement range from 47.7% to 57.1% was obtained in tensile strength. In addition, the impact of nanoparticle loading on the porosity was determined by applying the burning test and its effect on the mechanical properties was discussed

Multi-criteria decision-making approaches for aircraft-material selection problem

This paper is related to the use of multi-criteria decision-making (MCDM) tools for assisting material selection for aircraft parts. In this direction, decision models including analytic hierarchy process (AHP), complex proportional assessment (COPRAS), technique for order preference by similarity to ideal solution (TOPSIS), and Borda count methods were used to select the best materials for aircraft wings and nose. AHP was used to determine the criteria weights. According to the criteria weights, the rankings were obtained using AHP, COPRAS, and TOPSIS methods. Then, the final integrated rankings were obtained by Borda count method. Finally, the rankings obtained by AHP, COPRAS, and TOPSIS methods were compared to the final integrated rankings using Spearman's rank correlation coefficient

Material selection for fuselage using integrated SWARA-MULTIMOORA approach

Saf elementlerin yanında alaşımlama, ısıl işlem gibi ardıl işlemler ve kompozit malzeme üretimi ile mühendislik malzemelerinin çeşidi her geçen gün daha da artmaktadır. Böylesine geniş bir malzeme havuzundan, üretilecek her bir farklı parça için en uygun malzemenin seçimi ise oldukça önemli bir hal almaktadır. Uçağın önemli bir bölümünü oluşturan gövde için uygun malzeme seçimi de bu açıdan oldukça önemlidir. Yolcu uçağı gövdesi için malzeme seçiminin amaçlandığı bu çalışmada, öncelikle uzman görüşleri doğrultusunda kriterler ve alternatifler belirlenmiştir. Yoğunluk, çekme dayanımı, kayma dayanımı, maliyet gibi kriterlerin dikkate alındığı çalışmada, kriter ağırlıkları SWARA yöntemi elde edilmiş, ardından belirlenen kriter ağırlıkları doğrultusunda alternatif malzemeler MULTIMOORA yöntemi ile sıralanmıştır. Sonuç olarak, yolcu uçağı gövdesi için en uygun ilk üç malzeme sırasıyla CFRP, Ti-6Al-4V ve GFRP olarak belirlenmiştir

Investigation of the relationship between flexural modulus of elasticity and functionally graded porous structures manufactured by AM

There is an increased interest to produce open porous metallic lattice structures with regular unit cell architectures by additive manufacturing processes, which were impossible or difficult to manufacture using conventional techniques. In this study, the physical and mechanical properties of functionally graded porous structures were investigated to establish a relationship between porosity and elastic modulus of the cellular structure. Three different unit cell structures of diamond, cubic, and octahedroid and three different strut thicknesses of 0.3 mm, 0.5 mm, and 0.7 mm were designed for the experimental and theoretical study. A functionally graded porous structure was formed by using three different unit cell sizes (1.8 mm, 2 mm, and 2.2 mm) in each model. The specimens were produced by laser powder bed fusion (L-PBF) using Ti‐6Al‐4V powder and subjected to a three-point bending test after heat treatment. A mathematical model was created to determine the modulus of elasticity of the porous structures. Experimental results were compared with the theoretical calculations. As a result of this study, a correlation was established between the flexural modulus of elasticity and the porosity of the three different cell structures.Türkiye Bilimsel ve Teknolojik Araştırma Kurumu (TÜBİTAK), MAG-116R02

Investigation of tensile properties of glass fiber/ nanocomposites laminates enhanced with graphene nanoparticles

In this study, mechanical properties of graphene nanoparticles (GNP) added glass fiber/epoxy nanocomposite specimens and the effect of GNP were investigated by applying the tensile test. Specimens were produced by vacuum assisted resin transfer molding (VARTM) method on the CNC device in standard sizes. The results obtained from the tensile test of the specimens prepared with the addition of GNP at the rates of 0.15%; 0.25%; 0.35%; 0.45% and 0.75% were compared with the sample without GNP. According to the test results, the tensile strength increases with the increase in the rate of GNP. The highest tensile strength was found when the GNP rate was 0.45%. At this rate, the tensile strength increases by 31.29% compared to the specimens without additives. However, increasing the rate of GNP more than 0.45% affects the mechanical properties negatively and causes a decrease in tensile strength. Finally, finite element analysis (FEA) was made by designing the produced specimens. FEA results were compared and found to be compatible with the experimental results