Terms Of Ultimate Tensile Strength Research Articles

The effects of microstructural properties and temperature on the mechanical behavior of Nextel 720 composite fibers: A novel multiscale model

A novel multiscale technique called the Bridging Cell Method (BCM) was used to model the mechanical behavior of Nextel 720 composite fibers across a range of temperatures. The previously validated room temperature Nextel BCM was used as a benchmark, and a temperature-dependent formulation was employed to account for the temperature effect. The model was tested under uniaxial tensile loads ranging from room temperature to 1700 K. The results were evaluated in terms of ultimate tensile strength (UTS), elasticity, and failure strain. The temperature-dependent Nextel BCM was validated via experimental data obtained from the literature. The high-temperature drop in composite's strength was predicted by the Nextel BCM. This was the result of implementing the fibers' microstructural evolution into the model, caused by phase transformation occurring at higher temperatures. The model was further validated with the fracture resistance variations of the composite that resulted from changes in crack length. The fracture behavior of the fibers at room and high temperatures were tested, by applying inter- and intra-granular cracks. Finally, the effect of grain alignment with respect to the applied load was investigated. The results show that the Nextel BCM is capable of predicting Nextel 720 composite's mechanical behavior across a range of temperatures.

Investigation of Mechanical Properties of Ribbed Reinforcement Steel Bars: A Case Study on Ethiopian Construction Industry

This paper presents the annual report of the mechanical properties of ribbed reinforcement bars from construction sites taking projects as the case in and around Amhara, Ethiopia. Both imported and locally produced re-bars are used in the analysis without consideration of their varieties in the quality of the two sources. This paper focused on only with reinforcement bars of diameter 8, 10, 12 and 16 mm that accounted for 67% of the total tests. Using Universal Testing Machine, strength properties such as ultimate tensile strength (UTS), yield strength (YS), percentage elongation at fracture (%) and linear mass density property (kg/m) of steel reinforcing bars were analyzed for rebar diameters of 10, 12, 8 and 16 mm. Moreover, the results were analyzed by one-way analysis of variance (ANOVA). The results showed that the mean values of YS and UTS of all diameters surpassed the standard values recommended limit set by BS449: 1997 and ASTMA706. In addition, the mean values of percentage elongations for all tested steel products surpassed the 12% limit recommended by BS 449, 10% by ASTM A706 for all diameters. However, the mean mass per length values for 8, 10, 12 and 16 mm were below standard values set by ASTM A615/A615M. Furthermore, ANOVA indicated that the reinforced bars appeared to be dissimilar in terms of UTS and YS with 95% confidence, but the reinforced bars were similar to the elongation percentage.

Investigation of mechanical properties on Al 6061-B4C composite by squeeze casting process technique

Aluminum alloy is widely used in automotive, aerospace and other engineering industries because of its excellent mechanical properties. The main objective is to enhance 6061 Al alloy’s mechanical properties by producing 6061-B4C composite through squeeze casting process. Experimentation was carried out with different micron sizes and weight fraction of B4C particles. The mechanical properties of reinforced metal matrix were experimentally investigated in terms of Ultimate Tensile Strength and Hardness. We observe that these two properties are improved by the reinforcement of B4C particles and applied squeeze pressure.

Optimization of Process Parameters in TIG Welded Joints of AISI 304L -Austenitic Stainless Steel using Taguchi’s Experimental Design Method

Abstract Tungsten inert gas (TIG) welding is a fusion welding process having side range of applications in current industry. The TIG welding process parameters plays a very significant role in estimating the quality of a welded joint. So appropriate selection of welding process parameters is very much necessary to attain weld joint with increased tensile strength value. In the work, experiments were carried out on Austenitic Stainless Steel (AISI 304L) using Tungsten inert gas (TIG) welding process. In this study Butt welded joints have been made by using three levels of current, gas flow rate and nozzle to work piece distance. The quality of the weld has been estimated in terms of ultimate tensile strength of the welded specimens L9 orthogonal array of Taguchi‘s experimental design method was utilized for optimization of welding current, gas flow rate and nozzle to work piece distance on welded joints.

Nanocellulose-coated carbon fibers towards developing hierarchical polymer matrix composites

In this research, 0.1, 0.25 and 0.5 wt% MFC aqueous suspensions were used to impregnate carbon fiber fabrics via aspersion and immersion routes to build a cost-effective hierarchical polymer matrix composite laminates with enhanced load carrying capacity. Mechanical performance improvements of 28 and 21% were obtained in terms of ultimate tensile strength for 0.1 wt% MFC suspension via aspersion and immersion routes, respectively. The same impregnation conditions provided increments in tensile toughness of 52 and 31%, respectively, showing the positive role of the nanostructure as a strong interfacial agent. MFC solution aspersion was determined as the best impregnation procedure towards strengthening and toughening of the final product.

Impact of High-Intensity Ultrasound on Strength of Surgical Mesh When Treating Biofilm Infections.

The use of cavitation-based ultrasound histotripsy to treat infections on surgical mesh has shown great potential. However, any impact of the therapy on the mesh must be assessed before the therapy can be applied in the clinic. The goal of this study was to determine if the cavitation-based therapy would reduce the strength of the mesh thus compromising the functionality of the mesh. First, Staphylococcus aureus biofilms were grown on the surgical mesh samples and exposed to high-intensity ultrasound pulses. For each exposure, the effectiveness of the therapy was confirmed by counting the number of colony forming units (CFUs) on the mesh. Most of the exposed meshes had no CFUs with an average reduction of 5.4-log10 relative to the sham exposures. To quantify the impact of the exposure on mesh strength, the force required to tear the mesh and the maximum mesh expansion before damage were quantified for control, sham, and exposed mesh samples. There was no statistical difference between the exposed and sham/control mesh samples in terms of ultimate tensile strength and corresponding mesh expansion. The only statistical difference was with respect to mesh orientation relative to the applied load. The tensile strength increased by 1.36 N while the expansion was reduced by 1.33 mm between different mesh orientations.

Effect of Friction Stir Welding on Pitting and Stress Corrosion Cracking Behavior of AFNOR7020-T6 Aluminium Alloy

Present work mainly focused on the pitting and stress corrosion cracking behavior of AFNOR7020 aluminium alloy friction stir welds and compared those results with the base material. Initially, microstructural studies, TEM, microhardness tests, tensile tests and general corrosion properties of the welds were investigated. The elongated grains present in the base material have been transformed into superfine grains in the weld nugget. Transmission electron micrographs obtained from various regions of the weld indicated that almost all strengthening precipitates dissolved in the nugget region while partial dissolution of precipitates occurred in the thermo-mechanically affected zone and coarsening occurred in heat affected zone. Hardness in the weld nugget was found to be very nearer to the base material without considerable difference. The welds showed superior joint efficiency of 85% in terms of the yield strength and 95% in terms of ultimate tensile strength. General corrosion resistance of the welds was better than that of the base material at different pH value and spraying time. Pitting corrosion studies revealed that less significant difference in pitting corrosion resistance has been observed between the weld nugget and the base material. It was found that the susceptibility towards stress corrosion cracking is relatively more in base metal compared to welded joints. It has been concluded that friction stir welding plays a very important role in corrosion properties of the AFNOR7020 aluminium alloy.

Experimental studies on friction-stir welding of AA6061 using Inconel 601 tool

Nickel-based superalloy Inconel 601 has been used as tool material during friction-stir butt welding of AA6061-T6 plates. The unique properties of Inconel 601 viz. excellent high-temperature strength, strong work-hardening tendency, and high resistance to wear have been reported beneficial to utilize the material for potential use of FSW tool. Welding has been carried out in different combinations of tool rotation and traverse speed; joint performance in terms of ultimate tensile strength and micro-hardness has been studied. Optical microscopy has revealed existence of fine equiaxed gains at the nugget zone promoting relatively more refined grain structure as compared to the parent material. In few specimens, welding induced defects such as weld flash, kissing bond, zigzag line and tunnel defects have been identified. Maximum tensile strength ~ 133 MPa has been obtained at tool rotational speed ~ 1120 RPM and traverse speed ~ 40 mm/min. Fractographic analysis has revealed two distinct types of fracture mode in the specimens which have failed before the joint and at the joint, respectively. The specimens, failed before the weld zone, have corresponded to ductile fracture mode indicating dimples and ripples. On the contrary, beach marks (wavy patterns) have been noticed in the fractographic analysis of specimens which failed at the weld zone. After completing all welding experiments, the tool has been found not affected by wear, profile distortion by plastic deformation. Hence, application of the said tool can be advised provided the cost of machining the tool with desired pin profile is compromised.

Reactive molecular dynamics simulation of the mechanical behavior of sodium aluminosilicate geopolymer and calcium silicate hydrate composites

This paper for the first time used reactive molecular dynamics (MD) simulation to study the mechanical behavior of geopolymer binder (GB) and calcium silicate hydrate (CSH) composites. Specifically, GB-CSH composites with different Ca/Si ratios for the CSH phase were constructed and their mechanical behavior in terms of ultimate tensile strength, fracture toughness and strain energy release rates were investigated. It was observed that the Ca/Si ratio of CSH greatly affects the mechanical response of the composite. Increasing the Ca/Si ratio from 1.2 to 1.65 created more disorder in the silica layers in CSH and decreased the mechanical properties of the composite. However, the completely glassy CSH at a Ca/Si ratio of 2.0 showed slight improvement of mechanical properties due to high three-dimensional (3D) tetrahedral network. A detailed analysis of bond evolution and bond angle distribution showed their direct correlation with the observed mechanical response. The failure of the GB-CSH composites were always governed by the breaking of SiO bonds within the CSH, near the GB-CSH interface. Low Ca/Si ratio structures showed more SiO bond breakage, while in high Ca/Si ratio structures, deformation mobilization was accompanied by significant change in bond angles within GB.

Dynamic control of welding current and welding time to investigate ultimate tensile strength of miab welded T11 tubes

This study undertakes the objective of investigating the influence of welding current and welding time on the depth of penetration in Magnetically Impelled Arc Butt Welding classified under solid-state welding process. It is essential to create a parametric window for optimizing the range of process parameters that yields good mechanical properties expressed in terms of Ultimate Tensile Strength. This is attributed to the implications on the depth of penetration and the associated metallurgical properties. For this study, T11 tubes of 48–54 mm outer diameter with a thickness of 6.6–7 mm are adopted considering its versatile applicability in boiler and boiler accessory components. MIAB welding equipment available at welding research institute, BHEL is employed for this study. Welding current which is the key parameter that is segregated into three sections based on its differing implications on the weldment. On similar lines, the time zone is also divided into four sections. Each of them reveals significant effect on the joint properties. The welded specimens are subsequently subjected to tensile strength on a universal tensile testing machine. This is followed by development of a Double PI-PID control scheme to accomplish the improved system performance by operating it within the optimized range. A comparative study is presented on tuning of the developed controller by the conventional Zeigler-Nichols method and Auto tuning. The developed controller is then validated by comparing its performance with conventional PID controller. The stability analysis following the control scheme evaluation illustrates the accomplishment of persistent reliability and repeatability. The experimental values and the results of developed control scheme show good agreement with each other while also establishing its parametric control credibility. This study which is a conclave of mechanical/electrical and control engineering is expected to create better controllability and automate-ability there by facilitating the achievement of good weld in terms of strength and quality.

Synthesis and characterization of hybrid polypropylene matrix composites reinforced with carbonized Terminalia catappa shell particles and Turritela communis shell particles

ABSTRACTThe use of natural fillers in plastics to substitute conventional synthetic fibres is effective and economical. Eco-friendly bio-composites polypropylene matrix composites reinforced with blended carbonized Terminalia catappa (almond) shell particles and Turritela communis (periwinkle) shell particles were synthesized by mould casting. Five to twenty-five weight per cent of reinforcement was used and the microstructure, water absorption and mechanical properties of developed hybrid composites were evaluated. The microstructure showed a fairly uniform distribution of reinforcement particles in the matrix. The hybrid composite exhibited the best mechanical properties in terms of ultimate tensile strength (8.26 MPa), hardness (134.22 BHN), impact energy (21.81 J), and flexural strength (6.89 MPa) at 15 wt. % filler concentration. These indicate the efficacy of hybridization and the synergy between tropical almond shell ash and periwinkle shell particulates.

Experimental Investigation On Effect Of Welding Parameters On The Friction Stir Welding Of AA 6061

Friction Stir Welding (FSW) is a novel solid state welding process for joining of metallic alloys and has emerged as an alternative technology used in alloys that are difficult to join with conventional techniques. It uses a non consumable rotating welding tool to generate frictional heat and plastic deformation at the welded location while the material is in solid state. In this paper, the mechanical properties of welded joints of AA 6061 alloy were investigated to determine the effect on the mechanical properties of welding joints. FSW process was carried out at the various rotational speeds (1000, 1200 rpm) with welding speed 15 mm/min by using Half Groove Threaded (HGT) tool. Micrographs showed proper mixing at the higher rotational speed and at lower feed rate. The results in this study show that maximum welding efficiency of AA 6061 in terms of ultimate tensile strength, using 1200 RPM rotational speed, 15 mm/min traveling speed. By correlation of mechanical and metallurgical properties of welded sample at lower feed rate performed better in terms of ductility.

Weldability of AA 5052 H32 aluminium alloy by TIG welding and FSW process – A comparative study

Aluminium 5xxx series alloys are the strongest non-heat treatable aluminium alloy. Its application found in automotive components and body structures due to its good formability, good strength, high corrosion resistance, and weight savings. In the present work, the influence of Tungsten Inert Gas (TIG) welding parameters on the quality of weld on AA 5052 H32 aluminium alloy plates were analyzed and the mechanical characterization of the joint so produced was compared with Friction stir (FS) welded joint. The selected input variable parameters are welding current and inert gas flow rate. Other parameters such as welding speed and arc voltage were kept constant throughout the study, based on the response from several trial runs conducted. The quality of the weld is measured in terms of ultimate tensile strength. A double side V-butt joints were fabricated by double pass on one side to ensure maximum strength of TIG welded joints. Macro and microstructural examination were conducted for both welding process.

Influence of tool pin in friction stir welding on activated carbon reinforced aluminium metal matrix composite

This paper focus on impact of tool pin in friction stir welding on activated carbon reinforced aluminium metal matrix composite. For fabrication of metal matrix composite AA6061 is used as matrix and activated carbon is used as reinforcement and it is casted using modified stir casting technique. After casting metal matrix composite has undergone various microstructure tests like SEM,EDAX and XRD. FSW is carried out in this metal matrix composite by choosing various tool pin profile like square,round,Threaded round, hexagon and taper. The quality of welded plates is measured in terms of ultimate tensile strength and hardness.

Reinforcement effect of acid modified nanodiamond in epoxy matrix for enhanced mechanical and electromagnetic properties

We applied acid treatment for the surface modification of detonation nanodiamond (DND) powder by minimizing their surface energy to overcome agglomeration and improve dispersion of DNDs. Different concentrations of acid modified DND in 828 epoxy matrix were fabricated to check their mechanical and electromagnetic properties. Mechanical properties were checked in terms of ultimate tensile strength (UTS), toughness, energy to break, percent strain break and Young's modulus while electromagnetic shielding properties were studied in frequency range of 11–17GHz. To analyze electrical and magnetic properties of the nanocomposites, relative permittivity and permeability tests were performed. Excellent interactions among acid modified DND and epoxy resin was observed due to carboxyl and hydroxyl functional groups that results in the formation of efficient load transfer interface, which in turn enhance the mechanical and electromagnetic properties of epoxy nanocomposites. During investigation it was observed that mechanical properties and relative permittivity showed enhancements when, 0.2wt% acid modified DND were used as a nano-filler, while on further increment of modified DND these properties start decreasing. Unlike this, the relative permeability, reflection and transmission loss values were increased with the increase of acid modified DND content.

Effect of nano-sized B4C addition on the mechanical properties of ZA27 composites

In order to understand the influence of nano-sized B4C additive on ZA27 alloy, mechanical and physical properties of ZA27-B4C nanocomposites were investigated in terms of B4C content. While physical properties were determined in terms of microstructural studies, density and porosity tests, mechanical properties were determined in terms of ultimate tensile strength (UTS) and hardness experiments. Morphological and microstructural studies were carried out with scanning electron microscopy (SEM). The experimental results indicate that nano-sized B4C can be used to enhance the mechanical properties of ZA27 alloy effectively. The highest mechanical performance can be obtained at ZA27-0.5% B4C (in weight) nanocomposite with values of tensile strength (247 MPa) and hardness (141,18 BH) and low partial porosity (0.5%). After a pick point, increasing B4C ratio may cause the formation of agglomeration in grain boundaries, that’s why density, tensile strength, and hardness values are declined.

Synthesis and characterization of a model dual-phase system using the spark plasma sintering technique

Samples of a model dual-phase system, consisting of copper and AISI-420 martensitic steel have been synthesized using spark plasma sintering, with the objective of developing a microstructural analogue for dual-phase steels, in which the volume fraction and size of each phase can be controlled independently. Microstructural investigation of the samples, including fractography of samples deformed in tension until failure, show that densification is strongly temperature dependent. Samples sintered at temperatures of 900 °C or above at a pressure of 60 MPa show a density of more than 98%. The best mechanical properties, in terms of ultimate tensile strength and ductility is found in samples sintered at a temperature of 1000 °C, where a density of nearly 99% is achieved.

Corrosion of metals exposed to 25% magnesium chloride solution and tensile stress: Field and laboratory studies

The use of chemicals for snow and ice control operations is a common practice for improving the safety and mobility of roadways in cold climate, but brings significant concerns over their risks including the corrosive effects on transportation infrastructure and motor vehicles. The vast majority of existing studies and methods to test the deicer corrosivity have been restricted to laboratory environments and unstressed metals, which may not reliably simulate actual service conditions. As such, we report a case study in which stainless steel SS 304 (unstressed and externally tensile stressed), aluminum (Al 1100) and low carbon steel (C1010) coupons were exposed to 25% MgCl2 under field conditions for six weeks. A new corrosion test-bed was developed in Montana to accelerate the field exposure to this deicer. To further investigate the observed effect of tensile stress on the corrosion of stainless steel, SS 304 (unstressed and externally stressed) coupons were exposed to 25% MgCl2 solution under the laboratory conditions. The C 1010 exhibited the highest percentage of rust area and suffered the most weight loss as a result of field exposure and MgCl2 sprays. In terms of ultimate tensile strength, the Al 1100 coupons saw the greatest reduction and the unstressed and externally stressed SS 304 coupons saw the least. The ability of MgCl2 to penetrate deep into the matrix of aluminum alloy poses great risk to such structural material. Tensile stressed SS 304 suffered more corrosion than unstressed SS 304 in both the field and laboratory conditions. Results from this case study may shed new light on the deicer corrosion issue and help develop improved field testing methods to evaluate the deicer corrosivity to metals in service.

Refilling termination hole in AA 2198–T851 by refill friction stir spot welding

Friction stir welding features a joining technology with only few drawbacks. The exit hole inevitably left by the tool is a major disadvantage. In order to eliminate volume defects such as termination holes or voids in friction stir welds, refill friction stir spot welding was used for keyhole repair. The keyhole closure process was employed to 3 mm thick sheets of aluminum-lithium alloy AA 2198-T851. Exit holes with a diameter of 7.5mm in semi–stationary shoulder bobbin tool friction stir welds were refilled successfully.To characterize the refilling process characteristic process parameters such as position, force and torque of the tool parts have been monitored. The welds have been analyzed with regards to microstructural features, the local and global mechanical performance as well as the thermal cycle. The properties of the repair welds have been compared to friction stir welded butt joints and keyhole closure welds in bare sheet.A systematic investigation comparing and combining the two friction based processes has shown that refill friction stir spot welding is able to be applied as keyhole closure technique in sheet material and in semi–stationary shoulder bobbin tool friction stir welds. Defect free welds with known microstructural features were achieved. The mechanical performance of keyhole closure welds using refill friction stir spot welding in semi–stationary shoulder bobbin tool friction stir welds is comparable to the performance of keyhole closure welds in bare sheets. High-strength keyhole closure welds with efficiencies of 78 % in terms of ultimate tensile strength were achieved.

The development and mechanical characterisation of a novel reinforced venous conduit that mimics the mechanical properties of an arterial wall

Venous grafts have been used to bypass stenotic arteries for many decades. However, this “gold standard” treatment is far from optimal, with long-term vein graft patency rates reported to be as low as 50% at >15 years. These results could be a result of the structural and functional differences of veins compared to arteries. In this study we developed a new protocol for manufacturing reinforced fresh veins with a decellularized porcine arterial scaffold. This novel method was designed to be replicated easily in a surgical setting, and manufactured reinforced constructs were robust and easier to handle than the veins alone. Furthermore, we demonstrate that these Reinforced Venous-Arterial Conduits have comparable mechanical properties to native arteries, in terms of ultimate tensile strength (UTS) (2.36 vs. 2.24MPa) and collagen dominant phase (11.04 vs. 12.26MPa). Therefore, the Reinforced Venous-Arterial Conduit combines the benefits of using the current gold standard homogenous venous grafts composed of a confluent endothelial surface, with an “off-the-shelf” decellularized artery to improve the mechanical properties to closely mimic those of native arteries, while maintaining the self-repairing characteristics of native tissue. In conclusion in this study we have produced a construct and a new technique that combines the mechanical properties of both a natural vein and a decellularized artery to produce a reinforced venous graft that closely mimics the mechanical response of an arterial segment.