Evaluation Of Tensile Properties Research Articles

Evaluation of tensile properties of carbon fiber reinforced polymers produced from commercial prepregs

This paper presents the tensile properties of real products produced from prepregs based on the carbon fiber-reinforced polymer (CFRP) composite. In this study, we compared tensile properties of the two types of CFRP laminates with a different number of layers, different type of used carbon fiber woven fabrics, and epoxy resins. Both types are used for production of some interior and exterior parts of the luxury automobiles. This research showed that material No. 1 with DT121HT epoxy resin matrix, which has a higher number of reinforcing layers, is characterized by a higher value of tensile strength. Material No. 2 with DT121R epoxy resin matrix with higher reactivity and higher viscosity, which has a lower number of reinforcing layers, is characterized by a lower value of tensile strength. Reproducibility verification of tensile properties of both chosen materials showed that the CFRP laminates produced from commercial prepregs provide a guarantee of safety of the entire production of the CFRP parts.

Evaluation of tensile properties using uni-axial and ball indentation testing and correlation with microstructure variations across the 316LN stainless steel weld joints

Automated ball indentation (ABI) tests were conducted across the 316LN stainless steel (SS) weld joints at 298 K, and 823 K. Zone wise tensile properties of 316LN SS weld joints such as weld metal, heat affected zone (HAZ), and base metal region are evaluated in this work. Uniaxial tensile tests were conducted to assess the effect of welding processes on the tensile properties. The weld joints were initially fabricated using arc based and laser based welding processes. The variations of tensile properties such as yield strength, ultimate tensile strength and strain hardening component values across the heterogeneous microstructure zones of the weld joints were evaluated. The correspondence between the microstructure variations and the tensile properties have been studied. The variations in grain size, secondary dendrite arm spacing (SDAS) and δ-ferrite content are found to be the primary cause of tensile strength variation across the weld joints. The gradient in tensile strength across the weld joints was higher at 298 K than at 823 K which was attributed to the microstructural changes at higher temperature causing material softening. It was noticed that the 316LN stainless steel weld joint made by hybrid laser MIG welding exhibited the highest values of strength and ductility among all the weld joints. It was attributed to the combined effect of higher δ-ferrite content and finer SDAS values. Therefore, the HLM welding process is recommended for welding of 316LN stainless steel components from the point of view of better tensile properties.

Evaluation of tensile properties of fiber metal laminates under different strain rates

There has been an ever-going need for materials containing excellent mechanical properties, lower density, and improved fuel efficiency in the aerospace industry. To date, Fiber Metal Laminates (FMLs) are a prime choice for aerospace applications. The components of aircraft are subjected to various mechanical loadings under operating conditions; therefore, an in-depth understanding of material behavior under expected loading conditions is imperative for the meticulous design and manufacturing of these components. To evaluate the tensile behavior of the FMLs containing Aluminum 7075-T6 sheets as a metallic phase was the primary aim of this study. Furthermore, the manufactured composites were treated with the processes including surface de-greasing, mechanical abrasion, and anodizing. In order to perform mechanical characterization, uniaxial tensile tests were conducted at various strain rates 2×10−4 s−1, 5×10−4 s−1 and 8×10−4 s−1. The FMLs were fabricated through vacuum-assisted resin transfer molding (VARTM) process. The results revealed that FMLs based different combinations of the fiber and metal constituents exhibited a low degree of strain rate-sensitivity. In the case of CARALL, 1.7% increase in tensile strength was observed, and, its tensile strength was increased from 741 MPa to 754 MPa. Whereas, ARALL and GLARE laminates exhibited high degree of strain rate-sensitivity. When the strain rate is increased from 2×10−4 s−1, 5×10−4 s−1 and 8×10−4 s−1 the values are increased in the following patterns: 389 MPa, 411 MPa, and 475 MPa for GLARE laminates, and 253 MPa, 298 MPa 352 MPa for ARALL laminates. Thus, 39% and 22% increase in the tensile strengths were noted for ARALL and GLARE laminates, respectively.

Assessing the feasibility of fabrication and welding of nickel-alloyed ductile iron through the evaluation of tensile properties and mechanical characterization

Fabrication of metallic components using welding processes is of great importance in the engineering world. Alloying element added material is a necessary to fabricate industry-ready components, especially after the invention of fabrication methods using welding processes. In the present work, raw materials including iron scraps, sponge iron, and forged steel scraps are melted in a medium frequency furnace. Casting samples are cast produced as per the ASTM standards using nickel alloyed ductile iron and inspected for porosity and other defects. Tungsten inert gas welding is exercised to check for the suitability of produced alloy for the welding process. Mechanical characterization and tensile property of as-welded components were performed. Both cases were carefully examined and found with satisfactory results. Tungsten inert gas-welded samples were noticed without any weld defects; this opens the advantage to employ welding processes for the fabrication. This will certainly enhance the feasibility of welding process for various component fabrications.

Tensile properties evaluation of additively manufactured AISI 316L thin wall and bulk material using various miniaturized specimen geometries

Additive Manufacturing is an innovative technology, which allows creating structures of complex and unique geometries layer by layer. The mechanical properties of deposited objects can vary depending on their length, thickness and deposition orientation due to different cooling rates and various thermal conductivity. Austenitic steel AISI 316L, deposited using direct energy deposition technology, was an experimental material. The technology employs a high-power laser beam as an energy source for the powder melting. During the process, a powder is blown through the nozzle by protective gas into the processing area and subsequently molten. The aim of the study was to compare basic mechanical properties of the specimens extracted from a thin wall and a bulk material. The specimens were tested in horizontal and vertical orientations in relation to the build orientation in machined and as-deposited states. The tensile characteristics of proportional and non-proportional specimens were investigated within the study. The miniaturized tensile test specimens were employed in order to examine the strength and elongation of the experimental material. The mechanical testing results were complemented by microstructural analysis using a light microscopy (LM). Based on the obtained results, it can be concluded that the specimen proportionality affects not only the specimen elongation, but also the strength values of investigated material.

Evaluation of tensile and elastic properties of W/Cu cold-spray coatings for application to the FGM DEMO divertor concept

The ITER based conceptual design of EU DEMO divertor envisages tungsten monoblocks as plasma-facing material joined to a CuCrZr cooling tube with a thick Cu-OHFC interlayer. Since divertor configuration will define the power exhaust capabilities of the reactor, additional concepts have been developed within the EUROfusion WPDIV project. In this regard, FGM (Functionally Graded Material) concept is one of the proposed alternatives. The primary motivation of this concept is to replace the thick copper interlayer with a W/Cu compositionally graded thin film for armour-to-pipe joining with the aim of minimizing the stresses at the interfaces while assuring the structural integrity of the component. This FGM interlayer will be composed of stacked elementary layers manufactured by Cold-Spray with the following four target compositions: 100 vol.%Cu, 25 vol.%W + 75 vol.%Cu, 50 vol.%W + 50 vol.%Cu, 75 vol.%W + 25 vol.%Cu. The elastic modulus of these coatings is an especially important materials parameter since it has a strong influence on both FGM fracture and stress concentration at the interface. Therefore, it is of fundamental importance to determine the elastic modulus of the as-deposited coatings. In this work, the mechanical and microstructural characterisation of each elementary layer is presented, and different methods for the evaluation of their elastic modulus have been evaluated, and their agreement has been assessed. Tensile tests were conducted on the free-standing coatings to understand the strengthening and deformation mechanisms of each composition. The ultimate tensile strength increased proportionally with the W content, showing 50% higher tensile strength on the addition of less than 40 vol.%W since crack arresting tungsten particles were observed as strengthening mechanism.

Evaluation of microstructure and tensile properties of grain-refined, Ti-alloyed ferritic stainless steel fabricated by laser powder bed fusion

Many alloys produced by Laser Powder Bed Fusion (LPBF) suffer from coarse grains and anisotropic mechanical properties. Here, we investigate how the addition of Ti can cause significant strengthening via grain refinement in a model ferritic stainless steel. We perform LPBF experiments using elemental Fe, Cr, and Ti powders (with significant O impurity in the Fe powder) and perform microstructural analysis by SEM, EDS and EBSD as well as tensile tests on the alloys Fe-19at.%Cr and Fe-19at.%Cr-5at.%Ti. The Fe-Cr alloy displays very large grains after LPBF and a strong cube texture, rendering its mechanical properties similar to a single crystal. In the Fe-Cr-Ti alloy, TiO particle formation in the melt causes strong grain refinement, leading to a texture-free microstructure consisting of equiaxed grains ~1.6 μm in diameter. The 0.2% proof strength of the ternary alloy is more than double that of the binary alloy (281 MPa → 591 MPa), and the work hardening rate is also increased. While the elongation at fracture is reduced for the Fe-Cr-Ti alloy, at ~15 %, it remains sufficient, and samples show ductile fracture surfaces. We estimate that the grain refinement accounts for the majority of the strengthening, however, solid solution strengthening and the effect of the texture are also significant.

Experimental and computational evaluation of tensile properties of additively manufactured hexa- and tetrachiral auxetic cellular structures

The auxetic cellular structures with two different chiral geometries (tetrachiral and hexachiral) were fabricated using laser powder bed fusion (LPBF) technology from two different materials (aluminium alloy AlSi10Mg and stainless steel AISI 316L). The specimen's microstructure, porosity and surface texture were observed by X-ray diffraction, optical and electron microscopy and micro-computed tomography. The mechanical properties of all specimens were determined experimentally with a simple tensile test. The results show that hexachiral and tetrachiral auxetic structures have similar initial stiffness, whereas the former provides a more ductile response with more than four times larger failure strain. The AISI316L steel provides for a much more ductile response than AlSi10Mg at comparable normalised load-carrying capability. The samples' deformation behaviour was analysed with the digital image correlation and tracking method, where it was shown that hexachiral samples exhibit a lower Poisson's ratio. The experimental results were used to validate the corresponding computational models, providing a more detailed analysis of deformation behaviour. They allow for cost-effective parametric studies and the development of new optimised chiral geometries.

Comparative studies of experimental and numerical evaluation of tensile properties of Glass Fibre Reinforced Polyester (GFRP) matrix

The investigation and comparative analysis of Chopped Strand Mat Glass Fibre Reinforced Polyester (CSMGFRP) composite laminates was conducted. The laminate samples for the experiment were first exposed to diverse X-rays intensity rates at 6 mAs interval before test under cryogenic temperature. The generated values for tensile properties like young's modulus, strength, force, energy and elongation values were all measured and noted. The tensile modulus presented 43.8% decrease at the first 12 mAs exposure before it started increasing in the order of 30.3%, 6.3% and 12.3% respectively. Also, a science laboratory (SciLab) numerical evaluation of the material's tensile young's modulus was carried out and the obtained values compared with the experimental result to ascertain the level of relationship between the two approaches. It was observed that all the tested tensile properties were not consistent in the line of material strength depreciation values, apart from tensile young's modulus. The latter is consistent, but when considered with numerical model; their values became inconsistent like the former. However, when Analysis of Variance (ANOVA) for both approaches (experimental and SciLab numerical evaluations) were checked using t-test for pair comparisons, the data sets produced a computed t-value of 4.51. The obtained t-value and the critical t-value of 2.57 for 5% level of significance and 5-degree of freedom were compared, and it was noticed that the obtained t-value was higher than the critical t-value which indicated that the result was significant at the 5% level. Thus the null hypothesis is rejected which suggests that both approaches were relevant to tensile properties investigation at cryogenic temperature.

Effects of process interruptions on microstructure and mechanical properties of three face centered cubic alloys processed by laser powder bed fusion

Many factors can influence the thermal history during laser powder bed fusion (L-PBF) that contribute to the microstructure and mechanical performance of produced components. These factors can include process parameters, geometry, feedstock characteristics, and more. In this work, we report on the effect that process interruptions have on the thermal history during L-PBF fabrication of simple geometries made out of three alloys of interest: AlSi10Mg, Inconel 718 and Inconel 625. Systematic experiments were carried out with programmed process interruptions lasting one hour and simulating a stop to refill the system with powder, or an unexpected power outage. Specimens produced through these experiments enabled studying microstructural differences using microscopy techniques, and the evaluation of tensile and hardness properties when compared to uninterrupted controls. The findings from this study indicate that there were no distinguishable microstructural differences from interrupted specimens and uninterrupted controls for all three materials. Also, although Inconel 718 interrupted specimens showed a slight reduction in ultimate tensile strength and elongation, these properties remained essentially unchanged for AlSi10Mg and Inconel 625. Although a more comprehensive study is still required that accounts for the effect of thermal post-processing and other factors, the results described here provide several observations of the potential effects of process interruptions, and the implications towards process validation and quality assurance of L-PBF.

On hot isostatic pressing sintering of fused filament fabricated 316L stainless steel – Evaluation of microstructure, porosity, and tensile properties

Fused filament fabrication (FFF), as a low-cost additive manufacturing process to produce metallic components, has drawn significant attention. However, the pore chains that reside in between filament strands significantly deteriorate the mechanical properties and cause significant anisotropy. The purpose of the present research is to investigate the feasibility of using hot isostatic pressing sintering (HIP) to achieve pore closure and enhanced mechanical properties of FFF metal parts. The results show that the application of HIP sintering under 1320 °C for 1 h reduces the porosity to about 0.3 vol%. It eliminates the pore chains, leading to a high ultimate tensile strength of 540 MPa and significantly alleviated tensile property anisotropy. The microstructure of HIP sintered parts shows equiaxed grain morphology. The present study provides insight into a low-cost metal AM method with excellent mechanical properties comparable with other AM processes.

Evaluation of tensile properties of thermally aged 316LN stainless steel with varying nitrogen content using ABI technique

Abstract Type 316LN stainless steel (SS) with varying nitrogen content (0.07, 0.14 and 0.22 wt%) was thermally aged at 873 K and 923 K for 20,000 h. The microstructures of thermally aged steels revealed secondary phases such as M23C6 carbides and Fe–Cr–Mo intermetallics at all the nitrogen contents and Cr2N nitrides additionally at 0.14 and 0.22 wt% N. The amount of precipitates increased with increase in nitrogen content and aging temperature. The effect of thermal aging on the tensile properties of 316LN SS was evaluated using automated ball indentation (ABI) technique at 298 K. The flow curves of the steels aged at 873 K were lower than those obtained under unaged condition. Whereas due to ageing at 923 K, the flow stress response gradually increased above the unaged condition with increasing nitrogen content. The ultimate tensile strength varied similarly at 873 K aging condition for all nitrogen levels and was observed to recuperate upon aging at 923 K, except for 0.07 wt% N. Yield strength was not strongly affected by thermal ageing, except the considerable increase in 316LN SS with 0.22 wt% N aged at 923 K. The addition of nitrogen generally imparted interstitial solid solution strengthening to 316LN SS. The higher the nitrogen content and ageing temperature, the higher is the precipitation strengthening due to ageing, which was reflected in the tensile behavior. Transmission electron microscopy examination of ABI deformed zone revealed dislocation-precipitate interactions, precipitate-shear band interaction and pile-up of dislocations at precipitates, influencing the tensile properties.

Retracted] Evaluation of Microstructure, Hardness, and Tensile Properties: A Comparative Study of Stir Cast and Extruded Al7005/Glass‐/Fly‐Ash‐Reinforced Hybrid MMCs

The effect of extrusion ratio and addition of glass and fly ash on microstructural, mechanical properties, and fracture behavior of Al composites is examined. Both the composites and hybrid composites are prepared by the liquid metallurgical technique. Microstructure, extrusion effect on hardness, tensile properties, and fracture are studied using an optical micrograph, hardness tester, Universal Testing Machine, and scanning electron microscope, respectively. Experimental results show that increasing the extrusion ratio leads to a significant enhancement in mechanical properties such as tensile, compression, and yield strength and Young’s modulus, but results in a small reduction of ductility. It has been revealed that the presence of glass and fly ash improve the mechanical properties significantly with a slight reduction in ductility compared to the Al alloy. Fracture behaviour of the base alloy and composites show intergranular ductile and brittle cleavage mode failure as observed by SEM.

Evaluation of tensile and microstructure properties of AA2014 and AA7075 FSW weldments developed by HSS-10%Co and WC tools

Difficult to weld series of high strength Al grades by fusion welding were known to join by Friction stir welding (FSW) process. Joints of high strength AA 2021 and AA7075 base materials obtained by FSW technique were discussed in the present work. Tool materials with different surface hardness, High Speed Steel and Tungsten Carbide, were developed to commence welding. FSW Process parameters were taken as 1120, 1400 and 1800 rpm with feeds rates of 30, 40 and 50 mm/min. Base material and tool material combinations were chosen to produce weldments. Weld joints were evaluated using tensile test. Microstructure analysis was presented from the results of images obtained by Metallurgical Microscope. Weldments joined by HSS tool have shown better tensile properties compared to weldments obtained by tungsten carbine tool. Tunnels effects were seen in the weldments made from WC tool.

Evaluation of tensile properties of hybrid kevlar-glass reinforced epoxy composite for multi holes configuration

Abstract Most modern structures are comprised of synthetic composites with more number of cut outs. For the design of synthetic composite with varying shapes with different sized cut-outs are often used in engineering structures. The effects of stress concentration factor and tensile behaviour has to be thoroughly investigated for providing better design aids to be utilized by design engineers. The present paper focuses on the tensile behaviour of the Kevlar and glass fiber reinforced hybrid polymer composite by varying size and position of the cut outs. The test specimens are prepared according to the ASTM standard D3039. The composite laminates are prepared by traditional hand layup method. The overall dimension of plates were 25 mm*250 mm (width*length) and with the gauge length was 110 mm. These plates were drilled with the circular holes of 8 mm and 5 mm. The larger hole of diameter 8 mm was drilled at centre of all the specimens and smaller holes of diameter 5 mm was drilled on either sides of 8 mm hole. The pitch for smaller 5 mm holes were increased in the order of 0, 15, 20, 25 and 30 mm respectively. The specimen with smaller holes at 25 mm pitch showed highest allowable stress of 97.22 MPa. The experimental results were compared to find the optimum position for placing the holes. This research also intends to find out if there exists any relationship between the pitch, diameter of smaller and larger holes present in the specimen.

Evaluation of tensile properties of various regions of creep exposed dissimilar weld joint using miniature specimen testing

Strength variations in various regions of a dissimilar weld joint made between 316LN stainless steel (SS) and P91 steel after creep exposure at 550 °C and stress of 200 MPa was estimated using automated ball indentation (ABI) test. The ABI results were used to derive equivalent uniaxial tensile flow behaviour using established correlation factors. A comparison of the results obtained in the creep tested and post weld heat treated (PWHT) samples showed loss of strength in the P91 steel side. It was observed that, creep exposure under this testing condition strengthened the 316LN SS side of the weld joint. ABI derived results showed that, the inter critical-heat affected zone (IC-HAZ) of P91 steel is the weakest region across the weld after creep exposure. The narrow IC-HAZ created a strain constraint which caused the specimen to fail in the P91 steel base metal region.

Tensile and flexural behaviour of glass fibre reinforced plastic – Aluminium hybrid laminate manufactured by vacuum resin transfer moulding technique (VARTM)

The onset of technological advancements has resulted in the need for lightweight materials with superior properties for applications in critical areas such as aerospace and defence sectors, instigating the development of fibre metal laminates (FML). This paper focuses on the evaluation of tensile properties of the 5 layered glass fibre reinforced plastic (GFRP) – aluminium metal sheet (Al) laminate, fabricated by vacuum assisted resin transfer method (VARTM) fitted with spiral tube throughout the periphery of the laminated prepreg. The flexural and tensile properties of the manufactured composite were compared with theoretical values obtained from the FEA simulation of CAD models. The GF- Al composite manufactured by VARTM exhibited excellent properties in agreement with theoretical values that can be apparently attributed to the reduction of void formation in the composite as result of introduction of spirals throughout the length of the glass fibre – aluminium laminated composite.

Studies on the melt viscosity and physico-chemical properties of cellulose acetate propionate composites with lactic acid blends

Cellulose acetate has a high melting temperature due to intense intermolecular hydrogen bonding and is not significantly different from the deterioration temperature, so decomposition may occur during processing. Generally, in order to prevent pyrolysis of CA in the melting process, it is dissolved by using a solvent such as CS2 or H2SO4. However, it is not suitable for extrusion and injection process, and plasticized CA composition is prepared using plasticizer. In general, Dioctyl phthalate (DOP) is the most widely used plasticizer, and polyethylene glycol (PEG), glycerin (GC) triacetin (TA) and the like are partly used as environmentally friendly plasticizers. In this study, lactic acid was used as a compatibilizer and viscosity modifier in addition to plasticizer to prepare a composite. When the content of lactic acid is 5 wt% or more, phase separation occurs, so that the viscosity of the composition is controlled by blending in the range of 1 ∼ 5 wt%. The melting characteristics of the prepared compositions were confirmed by DSC and TGA, and specimens were prepared by injection molding. The effect of lactic acid content on the melt viscosity was measured and the yield stress, yield strain and elastic modulus were calculated by the evaluation of tensile properties. The composition of this study showed a viscosity change of about 10 ∼ 50% compared with the conventional one and the thermal properties were also different. The thermal properties were also different. In addition, the change of mechanical strength was observed depending on the degree of commercialization of additives.

Effect of Heat Input on the Microstructure and Mechanical Properties of Gas Tungsten Arc Welded AISI 316 Stainless Steel Joints

For every manufacturing industry, materials that are applicable for particular conditions and are of low economy are highly required. Hence various studies are carried out to determine the working conditions for several materials. The wide application of steel in industry demands a significance study on physical, chemical and mechanical properties of steel, Here, the characteristic changes in the mechanical and microstructure properties due to the effect of heat inputs of gas tungsten arc welded AISI 316 Stainless steel were examined. The major issue faced during the welding process of stainless steel is the increase in grain growth in the heat affected zone (HAZ). The welding process have been carried out using three heat input parameters on the AISI 316 Stainless steel from the operating window of the gas tungsten arc welding process (GTAW) and they are categorized as low heat (2.563 KJ/mm), medium heat (2.784 kJ/mm) and high heat (3.017 kJ/mm) . These welded joints of AISI 316 SS have been subjected to evaluation of tensile testing microstructure and mechanical properties so as to interrupt and infer the impact of thermal arc energy on the mechanical properties and microstructure of AISI 316 SS welded joints. From this study, it has been inferred that the heat input has notable effect on Ultimate Tensile Strength, Hardness and Microstructure on AISI 316 SS GTAW plates.

Evaluation of tensile properties on Glass/Carbon/Kevlar fiber reinforced hybrid composites

Composites made of synthetic fiber combined hybrid composites are find many industrial applications. Due to high strength to light weight ratio, higher modulus significantly reduced cost. In this research, composite fiber in woven mat form is added to matrix element with varying stacking sequences of symmetrical laminates. Four various hybrid laminate composites having glass, kevlar and carbon fibers are the reinforcements in varying stacking sequences are produced using hand lay-up technique followed by compression molding. The mechanical strength of the produced composite is evaluated. Experimental results found that composite having stacking sequences of Carbon-Kevlar- Carbon-Kevlar- Carbon (C-K-C-K-C) has the highest value of tensile strength 385.09 MPa respectively. Scanning Electron Microscope (SEM) is used to examine the morphology of fractured surface of hybrid composites during testing. SEM images revealed that hybrid composite with C-K-C-K-C had less defects on its fractured surface compared to other counter parts of the hybrid composites.