Terms Of Ultimate Tensile Strength Research Articles

Prediction of age-hardening behaviour of LM4 and its composites using artificial neural networks

This research work highlights the prediction of hardness behaviour of age-hardened LM4 and its composites fabricated using a two-stage stir casting method with TiB2 and Si3N4. MATLAB - Artificial Neural Networks is used to predict the age-hardening behaviour of LM4 and its composites. Experiments (hardness and tensile tests) are conducted to collect data for training an ANN model as well as to investigate the effect of reinforcements and age-hardening treatment on LM4 and its composites. The results show that with an increment in the reinforcement wt%, there is an enhancement in hardness and ultimate tensile strength (UTS) values within the monolithic composites. As-cast hybrid composites display a 37 to 54% improvement in hardness compared to as-cast LM4. Heat-treated samples, specifically those treated with peak aging with MSHT and 100 °C aging, perform better than as-cast samples and other heat-treated samples in terms of UTS and hardness. Compared to as-cast LM4, MSHT, and 100 °C aged samples display an 85 to 202% increment in VHN. Hybrid composites perform better in terms of hardness, while composites with 3 wt% of TiB2 (L3TB) perform better in terms of UTS, peak aged (MSHT and 100 °C aging) L3TB display 68% increment in UTS when compared to as-cast LM4. ANN model is developed and trained with five inputs (wt% of TiB2, wt% of Si3N4, type of solutionizing, aging temperature, and aging time) and one output (VHN) using different algorithms and a different number of hidden neurons to predict the age hardening behaviour of composites. Among them, Lavenberg-Marquardt (LM) training algorithm with normalized data and 30 hidden neurons performs well and shows a least average error of 1.588364. The confirmation test confirms that the trained ANN model can predict the output with an average %error of 0.14 using unseen data.

Enhancement of microstructure, micro-texture, and mechanical properties of Al6061 friction stir welds using the developed static shoulder welding tool

Dissolution of strengthening precipitates and grain coarsening are the key factors that dictate the mechanical properties of heat-treatable aluminium alloys. In this study, a feasible method of static shoulder friction stir welding (SSFSW) is used to reduce these adverse effects. A novel static shoulder friction welding tool is developed here in this study by incorporating rotating and non-rotating shoulders in a single tool. The effectiveness of the tool was evaluated by welding Al6061 plates under various conditions, such as conventional friction stir welding (CFSW), underwater friction stir welding (UWFSW), and SSFSW. The evolution of crystallographic texture and microstructural changes during the process is studied using electron back scattered diffraction and transmission electron microscopy. The results showed that SSFSW reduced grain size by 37% compared to UWFSW at the centre of the stir zone and increased the yield strength by 22.8% compared to CFSW. In addition, SSFSW showed a strong presence of γ-fibre, indicating improved formability and a 7.2% improvement in joint efficiency in terms of ultimate tensile strength due to a higher fraction of precipitates and higher dislocation density.

Study of the Friction Stir Welding For A516 Low Carbon Steel

The main objective of present work is to describe the feasibility of friction stir welding (FSW) forjoining of low carbon steel with dimensions (3 mm X 80 mm X 150 mm). A matrix (3×3) of weldingparameters (welding speed and tool rotational speed) was used to see influence of each parameter onproperties of welded joint .Series of (FSW) experiments were conducted using CNC milling machineutilizing the wide range of rotational speed and transverse speed of the machine. Effect of weldingparameters on mechanical properties of weld joints were investigated using different mechanical testsincluding (tensile and microhardness tests ). Micro structural change during (FSW) process wasstudied and different welding zones were investigated using optical microscope. The stir weldingexperiments conducted that show the low carbon steel can be welded using (FSW) process withmaximum welding efficiency (100.02%) in terms of ultimate tensile strength using best result ofwelding parameters (700 RPM, 25 mm/min, tool rotational speed and welding speed respectively and0.2 mm plunging depth of welding tool) ,there is afirst time that we obtain the efficiency reach to100.02 % to weld this type of low carbon steel by FSW. The corrosion resistance was measure whichis the new test on the welding by this way and we obtained different result from the result ontraditional welding processes and the result that obtained show the corrosion resistance for thiswelding plate better than the base metal. Maximum temperature has been calculated numerically byusing the ANSYS program. The obtained peak temperature is 1102°C, A percentage minimum of themelting point .

Effects of strain path on the microstructure, tensile properties, and formability of Al/Mg roll-bonded sheets

In this research, the experimental investigation of the change of the strain path on the microstructure, mechanical properties and the forming limit diagram of Al/Mg two-layer sheet made by roll bonding method has been performed. This research tries to make a two-layer Al/Mg sheet with a reduction ratio of 55% by using four single-pass and two-pass (the first pass with a reduction ratio of 40% and the second pass by changing the strain path in the form of direct rolling, reverse rolling and cross rolling) methods. The results show that the microstructure in cross rolling is more uniform than in other cases. No delamination is observed in fabricating the bilayer sheets with two passes. The best mechanical properties in terms of ultimate tensile strength and elongation are related to cross-rolled samples. Also, the cross rolling process causes a significant reduction in normal anisotropy. The comparison of formability for different conditions indicates the improvement of the forming limit diagram in cross rolling so that the amount of FLD0 for cross-rolled samples has increased by 15.6%, 13.8%, and 5.7%, respectively, compared to single-pass, two-pass direct rolling, and two-pass reverse rolling samples.

Mechanical property improvement of a AA6082 alloy by the TV-CAP process as a novel SPD method

AbstractTwisted variable channel angular pressing (TV-CAP) is a novel method. While it combines the advantages of equal channel angular pressing (ECAP), twist extrusion and direct extrusions, also it eliminates the disadvantages of these methods. Finite element analysis was also carried out in order to examine the design parameters, material flow and examine the effective strain values. Hardness and tensile tests were performed to examine the effect of TV-CAP on the mechanical properties of AA6082. In addition, optic microscope, SEM and TEM images were taken respectively and XRD, EDS and EBSD analyses were accomplished in order to investigate the microstructural analysis. As a result of this study, it has been observed that the material has hardened approximately 3 times compared to the annealed material and became 1.5 times stronger in terms of ultimate tensile strength. It was also concluded that, this new method is more efficient than twist extrusion and multi-pass equal channel angular pressing processes.

Improvement of tensile properties of carbon fibre-reinforced cementitious matrix composites with coated textile and enhanced mortars

Fibre Reinforced Cementitious Matrix (FRCM) systems are composite materials used for retrofitting structures thanks to their high strength-to-weight ratio and their compatibility with different substrates. The mechanical properties of FRCM depend on textile and mortar characteristics and on the interfacial bond behaviour between grid and matrix. In this research, FRCM systems made of two different carbon grids (one impregnated and one unimpregnated) and employing five different mortars were compared to assess the influence of both grid and mortar on the mechanical properties of the reinforcement. Tensile tests were carried out with a displacement and strain monitorization using Digital Image Correlation (DIC). The results reveal a remarkably better performance of the systems with impregnated grid, especially when combined with high strength mortars. The enhancement was particularly observed in terms of ultimate tensile strength, crack spacing, existence of a trilinear stress–strain curve, and efficiency factor (exploitation of the fibres in the composite).

Friction Stir Weldability at High Welding Speed of Two Structural High Pressure Die Casting Aluminum Alloys

In this work, the friction stir weldability of two structural high-pressure die casting aluminum alloys designed to manufacture thin-walled automotive components is investigated and compared. AlSi10MnMg and AlMg4Fe2 alloys were friction stir welded at a high welding speed (from 500 to 2000 mm/min) for a fixed rotation speed of 1500 RPM. The investigation was performed by studying the material flow influence on defect formation and microstructure, the mechanical properties of the welds and the forces that act during the friction stir welding process. The AlSi10MnMg alloy shows a lower incidence of defects than the AlMg4Fe2 alloy at all welding speeds investigated. Both materials present a great friction stir welding performance at 500 mm/min with a high joint efficiency in terms of ultimate tensile strength: 92% in AlSi10MnMg alloy and 99% in AlMg4Fe2 alloy.

Corrosion effect on structural behaviour of bolted steel connections under axial tension loads

Corrosion is one of the most important problems and is an inevitable event in metal structures exposed to environmental effects. Corrosion deterioration usually forms in steel and steel-concrete composite bridges and marine structures. Bolted connections in steel structures are the preferred connection types because of their ease of assembly and high strength. In this study, corrosion damages were created in steel plates with bolted connections and the axial load strength, ductility and behaviour of the steel members were investigated. Axial tensile tests have been carried out on steel plates with bolted connections exposed to corrosion at different rates (10% and 20% by mass). According to the axial tensile tests, decreases in average yield strength and average yield strain values were determined as 4% and 10% for 10% corroded specimens, and were determined as 16% and 27% for 20% corroded specimens having 4 mm thick plates, respectively. Similarly, for specimens having a thickness of 6 mm plate, average yield strength and average yield strain values decreased 3% and 5% for 10% corroded specimens, and 13% and 14% for 20% corroded specimens, respectively. Also, it was found that the ultimate strengths and average rupture strains decreased almost proportionally to the amount of corrosion. In addition, finite element analysis was performed in ANSYS program for bolted connections examined experimentally. In terms of ultimate tensile strength, the results were obtained with an average error of 4% in non-corroded 4 mm specimens and 6% in 10% and 20% corroded 4 mm specimens. For 6 mm plate thickness, these values of non-corroded, 10% and 20% corroded specimens were obtained as 9%, 5% and 3%, respectively.

Electrospun Silk Fibroin/kappa-Carrageenan Hybrid Nanofibers with Enhanced Osteogenic Properties for Bone Regeneration Applications.

Simple SummaryBone tissue engineering has recently been considered as a potential alternative approach to treating patients with bone disorders/defects caused by tumors, trauma, and infection. Scaffolds play a crucial role in the field because they can serve as a template that can provide optimal structural and functional support for cells. In this study, we prepared a series of electrospun silk fibroin/kappa-carrageenan nanofibrous membranes with the aim of mimicking bone extracellular matrix structure and composition and improving the biological properties of silk-fibroin-based nanofibers. Our research found that a combinational approach blending kappa-carrageenan and silk fibroin could enhance the biological properties of the nanostructured scaffold. kappa-carrageenan could also enhance the osteogenic potential and bioactivity properties of silk fibroin nanofibers, while genipin crosslinking preserved the mechanical strength of hybrid nanofibrous mats, indicating that the electrospun hybrid scaffolds could be a potential candidate for bone regeneration applications.In this study, a novel nanofibrous hybrid scaffold based on silk fibroin (SF) and different weight ratios of kappa-carrageenan (k-CG) (1, 3, and 5 mg of k-CG in 1 mL of 12 wt% SF solution) was prepared using electrospinning and genipin (GP) as a crosslinker. The presence of k-CG in SF nanofibers was analyzed and confirmed using Fourier transform infrared spectroscopy (FTIR). In addition, X-ray diffraction (XRD) analysis confirmed that GP could cause SF conformation to shift from random coils or α-helices to β-sheets and thereby facilitate a more crystalline and stable structure. The ultimate tensile strength (UTS) and Young’s modulus of the SF mats were enhanced after crosslinking with GP from 3.91 ± 0.2 MPa to 8.50 ± 0.3 MPa and from 9.17 ± 0.3 MPa to 31.2 ± 1.2 MP, respectively. Notably, while the mean fiber diameter, wettability, and biodegradation rate of the SF nanofibers increased with increasing k-CG content, a decreasing effect was determined in terms of UTS and Young’s modulus. Additionally, better cell viability and proliferation were observed on hybrid scaffolds with the highest k-CG content. Osteogenic differentiation was determined from alkaline phosphatase (ALP) activity and Alizarin Red staining and expression of osteogenic marker genes. To this end, we noticed that k-CG enhanced ALP activity, calcium deposition, and expression of osteogenic genes on the hybrid scaffolds. Overall, hybridization of SF and k-CG can introduce a promising scaffold for bone regeneration; however, more biological evaluations are required.

Optimizing FSW process parameters using RSM and regression analysis for similar and dissimilar aluminium materials

Aluminium hybrid composites were created using a modified stir casting process in this study. The casting yielded plates with dimensions of 100 mm, 50 mm, and 6 mm which were successfully butt connected using Friction Stir Welding (FSW). Four parameters were used to perform FSW; axial load, spindle speed, tool pin profile and aluminium material. The experiment was carried out utilizing the response surface approach of central composite design, which provides a pretty good prediction for all four parameters and 31 tests with a combination of input parameters were undertaken from the design. Regression analysis was used to examine the weld quality of welded specimens in terms of Ultimate Tensile Strength (UTS) and Hardness.

Combination of silk fabric and natural rubber for the development of green composites: Influence of curing on mechanical and thermal properties

Unmodified natural rubber is not suitable for any elstomeric applications. Therefore, it is appropriate to modify natural rubber chemically to enhance the stability, which can be termed as vulcanization. Incorporation of fibers/fabrics is a common method to increase the stability of natural rubber along with chemical modification. Natural rubber-based composites have been prepared by the addition of silk fabric into natural rubber. The matrix material for the composite is glutaraldehyde cured natural rubber. Silk is an ecofriendly and biodegradable material with excellent tensile strength. When such kind of fabric is introduced into the vulcanized rubber as the matrix, all the physical properties were found to be enhanced considerably. Tensile properties in terms of ultimate tensile strength, elongation at break, and modulus of elasticity are measured for the composites of natural rubber/silk fabric at various glutaraldehyde concentrations. Thermogravimetric analysis and temperature scanning stress relaxation techniques are employed to evaluate the thermal stability of the resulting composites. Effects of glutaraldehyde addition on the physical properties of the composite were studied in detail. Considerable enhancement in the stability of natural rubber in terms of tensile properties, thermal stability, and solvent resistance is noticed up on the incorporation of silk fabric as well as glutaraldehyde curing.

Grain characteristics and mechanical properties of as-cast Cu-10%Al alloy: Effects of alloying additions

In this research, a study between the microstructure and mechanical properties of Cu–10%Al alloy with the single addition of V, Ni, Mn, Nb and Cr at 5 wt% was carried out. This work aims to analyse the grain size criterion of Cu-10% Al alloy with various alloying elements. Six synthetic alloys of Cu%10Al were produced by sand casting using a bailout crucible furnace. Mechanical properties such as ultimate tensile strength, percentage elongation, hardness, and impact strength were determined on the alloys. The structural properties were examined by an optical metallurgical microscope and scanning electron microscopy (SEM). The average grain size, profile plot and grain size distribution were also determined using ImageJ software. The results indicated that Cu10%Al alloys with alloying elements had improved mechanical properties compared to Cu–10%Al alloy without alloying elements. Cu–10%Al–5%Nb alloy showed the optimum performance in terms of ultimate tensile strength and percentage elongation, while Cu–10%Al–5%Mn alloy gave peak value of hardness and impact strength. From structural observation, α-phase, β-phase, and intermetallic phases such as fine stable reinforcing kappa phase and coarse α+γ2 phase were detected and allied to the properties enhancement. The properties improvement is directly dependent on the grain refinement of the microstructures as the average grain size of the parent alloy decreased from ≈16.54 μm to ≈11.08 μm after the adding of alloying elements.

Effect of thermal aging on metallurgical, tensile and impact toughness performance of electron beam welded AISI 316 SS joints

Abstract Electron beam welding was used to fabricate a fully penetrated joint of 18 mm thick AISI 316 stainless steel plates. The effects of carbide precipitation on the metallurgical and mechanical properties of the weld were evaluated after aging at 750 °C for 300 h. The optical microstructure analysis showed that the weld zone consists of skeletal, vermicular, lathy, and lacy ferrite which further transformed into carbides after thermal aging. The weld zone was weaker in terms of ultimate tensile strength as compared to the base metal, as the presence of ferrite content (varied from 8% to 2.9 %) in the weld zone. Analysis along the thickness of the welded joint revealed that the bottom of the weld bead possessed 6% higher ultimate tensile strength as compared to the top of the weld bead. The microhardness and impact toughness in as-welded specimens got increased by 12.5 % and 49.5 % respectively while traversing from top to root of the weld bead. Thermal aging promoted the formation of Cr rich carbides (Cr23C6) on the grain boundaries and reduced the delta ferrite content near to zero. Further, it led to a reduction in the impact toughness by 62 % at the bottom of WZ and increased the ductility and the microhardness of the weld bead.

Surface optimization of detonation nanodiamonds for the enhanced mechanical properties of polymer/nanodiamond composites

The surface of agglomerated nanodiamond (ND) particles was modified with carboxylic acid and ammine moieties using UV/ozone and ball milling methods respectively. The microstructural analysis revealed that the initial agglomerated NDs clusters were predominantly reduced in size with the UV/ozone and ball milling treatments. The UV/ozone and ball mill functionalized NDs were kept for dispersion under observations into ethanol, water and dimethyl sulfonic oxide (DMSO) solvents. The dispersion images satisfactorily showed that all the surface modified NDs samples reveals good dispersion tendency comparatively to pristine NDs whereas, the ball mill treated NDs showed outstanding dispersion behavior rather than all samples. Furthermore, the mechanical properties were investigated using various amounts of surface modified NDs in epoxy matrix. The mechanical properties were checked in terms of ultimate tensile strength (UTS), Percent break strain and Flexural strength. The results of all the mentioned mechanical properties revealed that 0.3 wt% was the optimum amount for getting highest properties. Similarly ball mill treated NDs represented the remarkable enhancements in all mechanical performances comparatively to pristine and UV/ozone treated ND samples.

Microstructure and properties of high-strength C + N austenitic stainless steel processed by laser powder bed fusion

In the developing field of laser powder bed fusion (L-PBF), austenitic stainless steels, such as AISI 316L, have gained great importance owing to their excellent processability. However, the moderate strength of these steels limits their applicability. This can be counteracted by the use of nitrogen as an alloying element to improve both strength and corrosion resistance.In this work, nitrogen-alloyed high-strength austenitic stainless steel X40MnCrMoN19-18-1 was processed by L-PBF, and the resulting microstructural and mechanical properties were investigated. The same material was also processed by hot isostatic pressing (HIP), which was used as a reference state. In the L-PBF process, argon and nitrogen were used as process gases to investigate the influence of process atmosphere on the microstructure and on changes in the chemical composition during processing. The results show a minor decrease in the nitrogen content of the steel after L-PBF, independently of the process gas, whereby argon resulted in a slightly higher specimen density. The microstructure after L-PBF processing contained small precipitates that could be removed by a short solution-annealing treatment. The tensile properties of the L-PBF-built steel are comparable to those of the steel produced by hot isostatic pressing in terms of ultimate tensile strength, but had lower elongation to fracture values. The ductility of the material was enhanced by solution annealing without significant impairment of the ultimate tensile strength. This work demonstrates that nitrogen-alloyed stainless steels can be processed by means of L-PBF and can extend the variety of appropriate steels towards applications with high requirements for the material strength and chemical resistance.

Mechanical properties of carbon fiber reinforced plastic obtained by the automatic deposition of an innovative towpreg

In the present work, the lay-up process of carbon fiber thermoset towpregs was investigated by means of a numerically controlled fiber placement machine developed by Comec Innovative. The effect of both the compaction pressure by the roller and the resin weight fraction prior to cure on the mechanical properties of composite laminate, in terms of ultimate tensile strength and elastic modulus, was studied. Finally, samples were observed by means of the scanning electron microscopy in order to achieve high resolution observation of the three-dimensional topography of microstructure.

A Novel Method for Predicting Tensile Strength of Friction Stir Welded AA6061 Aluminium Alloy Joints Based on Hybrid Random Vector Functional Link and Henry Gas Solubility Optimization

Aluminum alloys have low weldability by conventional fusion welding processes. Friction stir welding (FSW) is a promising alternative to traditional fusion welding techniques for producing high quality aluminum joints. The quality of the welded joints is highly dependent on the process parameters used during welding. In this research, a new approach was developed to predict the process parameters and mechanical properties of AA6061-T6 aluminium alloy joints in terms of ultimate tensile strength (UTS). A new hybrid artificial neural network (ANN) approach has been proposed in which Henry Gas Solubility Optimization (HGSO) algorithm has been incorporated to improve the performance of Random Vector Functional Link (RVFL) network. The HGSO-RVFL model was constructed with four parameters; rotational speed, welding speed, tilt angle, and pin profile. The validity of the model was tested, and it was demonstrated that the HGSO-RVFL model is a powerful technique for predicting the UTS of friction stir welded (FSWD) joints. In addition, the effects of process parameters on UTS of welded joints were discussed, where a significant agreement was observed between experimental results and predicted results which indicates the high performance of the model developed to predict the appropriate welding parameters that achieve optimal UTS.

Effects of Cooling Conditions on Microstructure and Mechanical Properties of Friction Stir Welded Butt Joints of Different Aluminum Alloys

The aim of this work is to evaluate the difference between the properties of several aluminum alloy joints welded with the traditional air-cooled friction stir welding process and others obtained by the combination of the traditional friction stir welding setup with a water-cooling system. In particular, precipitation-hardening alloys AA2024-T3, AA6082-T6 and AA7075-T6, and a work-hardening alloy, AA5754-H111, were taken into account. From Rockwell and Vickers hardness maps, it was possible to observe a clear dependence of the hardness distribution on the cooling systems; joints obtained using a water-cooling system showed higher values of hardness, reached in the central zone and a narrow area interested by the hardness reduction for all the tested alloys. From tensile tests executed orthogonally to the welding direction, it was possible to observe that the alloys have responded differently in terms of ultimate tensile strength and final elongation when the water-cooling system was used. The microstructural analysis of the three precipitation-hardening alloys showed a larger average grain size in the nugget zones for the water-cooled condition. Moreover, in the thermo-mechanically altered zones of the water-cooled AA6082 and AA7075 joints, the grains were characterized by a smaller average size than the grains of the same air-cooled welds.

Modeling of friction stir welding process using adaptive neuro-fuzzy inference system integrated with harris hawks optimizer

Friction Stir Welding (FSW) has been paid more attention in recent years due to its efficiency in welding materials that are difficult to weld by conventional fusion welding methods. There are several parameters that affect FSW process, so it is important to understand the relationship between different process parameters to maximize the quality and strength of the joint. This paper proposed an alternative method to predict FSW parameters and make a decision using a modified version of the adaptive neuro-fuzzy inference system (ANFIS) integrated with harris hawks optimizer (HHO). HHO was used to search for optimal values of ANFIS parameters and to determine the optimal operating conditions of the FSW process. The shared effect of welding speed, tool rotational speed, and plunge force on the mechanical properties of welded aluminium plates was simulated. The proposed model, called ANFIS-HHO, was used to predict the mechanical properties of FSW Al plates in terms of ultimate tensile strength (UTS) as functions of welding speed, tool rotational speed, and plunge force. The adequacy of the model was tested; the predicted data were in good agreement with the experimental data. The tool rotational speed and the empirical force index (EFI) have a significant impact on the mechanical properties of the welded joints. ANFIS-HHO technique was found to be a powerful optimization tool for predicting FSW parameters to achieve high joint strength.

Effect of Agro Waste Particles on the Mechanical Properties of Hybrid Unsaturated Polyester Resin Matrix Composites

The efficacy of reinforcement of polyester resin matrix composites with agro waste particles to effect improvement on the disadvantage of low mechanical properties for optimal performance was studied. 5-25 wt. % of coconut shell, periwinkle shell, and cow bone particles were applied in reinforcing unsaturated polyester resin matrix by mould casting and the microstructural and mechanical characteristics of the composites were evaluated. There was uniform distribution of the agro waste particles in the polymer composites matrix from the scanning electron microscopy (SEM) result. The hybrid composite at 15 wt. % reinforcement demonstrated the highest mechanical properties in terms of ultimate tensile strength (66.73 MPa), flexural strength (76.76 MPa), hardness (87.76 BHN), and impact energy (23.16 J). This shows the efficacy of hybridisation and the high potential of the composite for wider applications.