Tensile Test Specimens Research Articles

Optimization of friction stir processing parameters to improve mechanical properties and microstructure of Al5083 aluminum alloy reinforced with AlCoCrFeNiSi high-entropy alloy

Abstract This study explores integrating AlCoCrFeNiSi high-entropy alloy (HEA) particles into the Al5083 aluminum alloy matrix via Friction Stir Processing (FSP) to enhance mechanical characteristics. Microstructural analysis reveals a homogeneous distribution and size reduction of HEA particles, contributing to improved structural strength. X-ray diffraction (XRD) examination confirms the formation of solid solution phases in the HEA particles, validating their role in enhancing material properties. Through the utilization of Design of Experiments (DOE) and Response Surface Methodology (RSM), FSP parameters are systematically optimized, enabling precise predictions of mechanical behavior. Multi-response optimization identifies the optimal combination of FSP parameters, resulting in significant enhancements in Ultimate Tensile Strength (UTS) and Hardness, reaching 314 MPa, 42% elongation, and 75 HV, respectively. Scanning Electron Microscopy (SEM) analysis of tensile test specimens elucidates the impact of varied FSP parameters on microstructural features, emphasizing the importance of optimal mixing for improving interfacial bonding and mechanical properties. This study underscores the effectiveness of integrating HEA particles and optimizing FSP parameters to elevate the mechanical properties of Al5083 aluminum alloy, paving the way for tailored composite materials with enhanced performance for specific applications.

The effect of building strategies on tensile strength of additively manufactured parts by laser metal deposition

Abstract Laser Metal Deposition (LMD) is a powder-based technology. This technology can be used for surface coating, repairing and additive manufacturing. The property of the part is dependent on the building parameters of the process. In the research work, we use austenitic steel (316L) powder to produce blocks with different building strategies, from which we machine tensile test specimens. The patterns were prepared according to three strategies: the welded bands were parallel to the longitudinal axis of the test specimen, perpendicular to it, and finally the parallel and perpendicular directions were alternated. We perform hardness and tensile tests on these specimens and search for correlations between the strength and the strategies.

Microstructural and mechanical characterizations of weld metal of S960QL ultra high strength steel joints obtained with different multi-pass laying techniques using GMAW

Abstract 15 mm thick ultra-high strength steel plates with 960MPa yield strength were welded using different multi-pass laying techniques (i.e., stringer and weaving beads) with torch manipulation. Weld metals obtained were compared using different mechanical (i.e., micro tensile tests and Vickers hardness maps) and microstructural (i.e., optical microscope, scanning electron microscope, X-ray diffraction, electron backscatter diffraction) characterization techniques. Coarser grains and acicular ferrite were observed in weld metal obtained with weaving pass procedure. There were hardness differences in face and root passes of both weld metals. Yet, hardness values were 19% and 11% higher for face and root regions of the joint obtained by stringer pass procedure, respectively. Fractographs of micro tensile test specimens revealed dimples depicting ductile network structure for both joints.

Influence of additive manufacturing parameters by FFF on PLA tensile strength

When na object manufactured by 3D printing goes from prototype to a functional component, it is crucial to understand the mechanical properties of the material used. This knowledge determines the resistance limits of the object. Therefore, the objective of this research was to comparatively analyze the results obtained in tensile tests of specimens constructed with polylactic acid (PLA), printed in 3D, keeping the density constant and varying two construction parameters: the layer thickness and the geometry of the internal filling. The test specimens were made on a BFB Touch – Dual head-smoke 3D printer, in accordance with ASTM D638-14. Tensile tests were carried out using an EMIC model DL10000 testing machine, and the results were statistically analyzed for comparison. The results indicated that the maximum stress and fracture resistance increased with increasing thickness of the filament deposited by the extruder nozzle. Although PLA is often described in the literature as a brittle polymer, it has exhibited ductility characteristics when 3D printed, due to the alignment of fibers during the manufacturing process.

Experimental Determination of Tensile Stress Concentration Factors of 3D-Printed PLA Polymers: Fillet Radius, Hole Diameter, and Infill Density

3D-printing technology is being used as a regular approach in prototyping and the production of machine components. However, despite their metallic counterparts, there are many issues including infill pattern, density, and stress concentration coefficient in 3D printing that are not well-defined. The infill density plays a significant role in the printing time and mechanical properties of the printed objects. On the other hand, like metallic materials, changing geometry, such as fillet radius and hole alters the strength of the printed elements. In this work, experimental works have been conducted to determine the effect of infill density on the tensile strength of 3D printed elements. Furthermore, various standard specimens for tensile testing have been prepared to investigate the effects of fillet radius and in-plane hole diameters on the tensile strength of PLA 3D-printed elements with different infill density. Using the experimental results, the tensile stress concentration coefficients as a function of fillet radius, hole diameters, and infill density have been determined. The results of the present work can be used as a guideline for analytical design and manufacturing 3D printing objects.

Mechanical characterisation and high temperature analysis of hyperelastic adhesives – Modelling and experimental validation

Adhesive bonds are subject to multiple environmental conditions that can affect their mechanical performance during service. Therefore, it is important to evaluate the influence of temperature on adhesive strength, as it can impact joint safety and should be considered during the design phase. This study presents an analysis of the effect of high temperatures on the mechanical behaviour of joints made with highly elastic adhesives, specifically a polyurethane and a silicon-modified polymer. Shear and tensile tests were conducted at temperatures of 23, 50, and 80 °C using dumbbell specimens for tensile tests and single lap specimens (SLJ) for shear tests. The tests were performed with two different substrates, aluminium (Al) and glass fibre reinforced polyester panel (GRP), and with varying adhesive thicknesses. These tests aim to assess the impact of temperature conditions on the mechanical properties of the adhesive and the behaviour of the joints. The analysis of the experimental results reveals that the adhesive degrades when exposed to high temperatures, resulting in reduced strength and stiffness, and less linear behaviour.Furthermore, this work involves the determination of a model able to reproduce the mechanical behaviour of hyperelastic adhesive at high temperatures, considering diverse constitutive modelling approaches. To achieve this, a testing protocol was conducted on basic uniaxial and planar specimens. The results indicate that the Ogden N=2 model is the most suitable for representing the non-linear behaviour of the hyperelastic adhesive at high temperatures. In contrast, the Mooney Rivlin model is more suitable to represent the material behaviour under ambient conditions. To conclude this work, the law has been satisfactorily validated by comparing the results of tests carried out on SLJ specimens with different adhesive thicknesses.

A Relationship between Fracture Toughness Kc and Energy Release Rate Gc According to Fracture Morphology Analysis

This study investigated the relationship between fracture toughness (Kc) and energy release rate (Gc) through fracture morphology analysis, emphasizing the critical role of fractal dimensions in accurately characterizing fracture surfaces. Traditional linear elastic fracture mechanics (LEFM) models relate Gc to Kc by combining energy principles with the nominal area of the fracture surface. However, real materials often exhibit plasticity, and their fracture surfaces are not regular planes. To address these issues, this research applied fractal theory and introduced the concept of ubiquitiform surface area to refine the calculation of fracture surfaces, leading to more accurate estimates of Gc and Kc. The method was validated through standard compact tensile specimen tests on a nickel-based superalloy at 550 °C. Additionally, the analysis of fractal dimension differences and dispersion in various fracture regions provides a novel perspective for evaluating the fracture toughness of materials.

Effect of process parameters on mechanical and tribological characteristics of FDM printed glass fiber reinforced PLA composites

PurposeAdditive manufacturing of polymer composites is a transformative technology that leverages the benefits of both composite material and 3D printing to produce highly customizable, lightweight and efficient composites for a wide range of applications.Design/methodology/approachIn this research work, glass fiber-reinforced polylactic acid (PLA) filament is used to print the specimen via fusion deposition modeling process. The process parameters such as infill densities (40%, 50% and 60%) and raster angle/orientations (0°, 45° and 90°) are varied, and the specimens for tensile, flexural, impact, hardness and wear testing are prepared as per their respective ASTM standards.FindingsThe results revealed that with an increase in infill density, the mechanical properties of glass fiber-PLA specimens increase progressively. Optimal tensile properties and flexural properties are obtained at 0° and 90° raster angle orientations and 60% infill density. Minimum wear rate is achieved at 0° raster angle orientation and it increases at 45° and 90° raster angle orientations.Originality/valueUsing SEM, the microscopic analysis of the fractured specimen was analyzed to study the interface between the fibers and matrix and it indicates the presence of good adhesion between the layers at 60% infill density and 0° print orientation.

Revealing the Relationship between Critical Inlet Velocity and a Double-Layer Oxide Film Combined with Low-Pressure Casting Technology

In the context of low-pressure casting, an excessive inlet velocity may result in the introduction of an oxide film and air into a liquid metal, leading to the formation of a two-layer film structure within the casting. Such defects can significantly degrade the mechanical properties of the castings. In order to optimize the advantages of low-pressure casting, an empirically designed equation for the inlet velocity was formulated and the concept of critical inlet velocity was further refined. A comprehensive numerical simulation was conducted to meticulously analyze the liquid metal spreading phase within the cavity. Subsequently, low-pressure casting experiments were carried out with actual castings of an A357 alloy, using two different entrance velocities—one critical and the other exceeding the critical entrance velocity. Tensile test specimens were extracted from the castings for the comparative evaluation of mechanical properties. It was observed that the average tensile strength of specimens cast at the critical inlet velocity exhibited a notable 16% enhancement. In contrast, specimens cast at velocities exceeding the critical inlet velocity manifested the presence of double oxide film defects. This evidence suggests that casting at a velocity faster than the critical inlet velocity leads to the formation of double oxide film defects, which in turn reduces the mechanical properties of the castings.

Fabrication and Testing of Hybrid Polymer Composite Material by Using Carbon, Glass, Kevlar Fibers

Composites which made up of fiber reinforcements are universally endorsed option for the automobiles with a lightweight. Due to the unique properties of fiber-reinforced composites, it became a perfect alternative for traditionally used materials. Most of the automobile industries prefer polymer matrix fiber-reinforced composites for the reason that its light weight helps in carbon emission reduction and Additive manufacturing (AM) produces a complex shaped product from its data, layer by layer, with high precision and much less material wastage. As compared to the conventional manufacturing process, there are many positive environmental advantages of additive manufacturing technologies. Most importantly, there is less waste of raw material and the use of new and smart materials. In this work, we first focused on creating the composite material utilizing the Hand Lay-Up method with materials such as Carbon Fiber/Epoxy Composite with Copper Oxide (CuO) Nanoparticles and Banana Glass Fiber. Following that, we readied ASTMD638 specimens for both compressive and tensile testing. We created an ASTMD638 model for the investigation's tensile and compressive tests using Solid Works design program, and we then saved the design model in STL format. This STL format was uploaded into the CURA software for slicing. The slicing model was then saved into G-code format, and it was printed in a fused deposition modeling machine. Lastly, we tested both specimens using a compressive test setup in a Universal Testing Machine model (INSTRON-3369) UTM, and the results showed 3D printed files. Keywords: Glass Fiber, Banana Fiber, Carbon Fiber, Copper Oxide Nano filler, 3D printing Machine,Corbon Fiber Filament.

Anisotropic polymer components with desired elastic properties manufactured through fused filament fabrication additive manufacturing

AbstractFused filament fabrication (FFF) is a popular additive manufacturing (AM) process, primarily used for fabricating polymer components. Optimizing the mechanical properties of FFF components, such as their elastic moduli, is crucial in many applications. This study focuses on adjusting the elastic properties of polymer components manufactured through FFF process by selecting appropriate process parameters. The elastic constants of the anisotropic FFF components are measured by using ultrasonic testing (UT). Response surface methodology (RSM) is employed to determine the optimal settings for these parameters to achieve the desired elastic properties. The effects of layer thickness, printing speed, and raster angle on Young's modulus are explored. Analysis of variance (ANOVA) is used to identify the contributions of each process factor on the output responses. According to ANOVA results, the optimal conditions identified are: a printing speed of 2040 mm/min, a layer thickness of 0.2 mm, and a raster angle of 29°. These conditions collectively achieved the maximum Young's modulus. The differences between the predicted and measured moduli for all responses are less than 5%. The structural factors influencing the results are examined by analyzing the fracture surfaces of the tensile testing (TT) specimens with field emission scanning electron microscopy. Additional measurements of other properties, including ultrasound velocity and wave attenuation, are conducted on the samples. The findings indicate that optimizing the parameters by setting them to their minimum values does not only improve the maximum elastic modulus in specific directions but also reduces attenuation. It is concluded that the desired elastic modulus for a component can be achieved by properly adjusting the process parameters.Highlights Optimizing AM parameters to achieve the desired elastic properties of FFF samples. Examining the effects of each AM parameter by utilizing ANOVA and RSM methods. Measuring the anisotropic elastic properties of AM samples by UT. Verifying UT results through TT and measuring attenuation.

Effects of Static Strain Aging on Mechanical Performance of Ductile Cast Iron

EN-GJS-400-15U nodular cast iron intended to be used as load-bearing element in long-term geological disposal canisters containing spent nuclear fuel in Finland and Sweden was studied for static strain aging (SSA). Tensile test specimens manufactured from the nodular cast iron were pre-strained to 1%, 2% and 3% nominal plastic strains. The pre-strained specimens were aged at different temperatures ranging from room temperature to 400 °C for varying times. The aged specimens were tested with conventional tensile testing using constant cross-head speed of 0.016 mm/s. Additionally, four specimens were studied with digital image correlation (DIC) during the tensile testing to obtain full-field strain measurements. SSA resulted in elevated pronounced yield point in all the conditions, while the as-received material showed continuous yielding behavior. SSA reduced the elongation to fracture. DIC tests showed more localized yielding behavior in the SSA specimens. Over-aging effect was observed at 400 °C where increasing pre-strain did not increase the yield stress more. For 1-day aging time, the highest yield stress increment was found after aging at 200°C. The yield stress of the material was almost identical after aging in 100°C and 200°C.

Investigation of Influence of Variations of Ageing Conditions on Aluminium-Silicon: Pathway to Tailored Mechanical Properties

This study focuses on the investigation of the influence of the variations of ageing conditions on the mechanical properties of ferrosilicon-silicon carbide reinforced Aluminium metal matrix composites. The ageing temperature, reinforcement percentage volume fractions and ageing time of the composite were systematically varied during fabrication stages by keeping the Aluminium and Ferrosilicon compositions constant while varying the percentage volume fractions of Silicon Carbide (SiC). The samples produced were machined into hardness, impact and tensile tests specimens. Then the specimens were subjected to laboratory based accelerated solution heat treatment, quenching and artificial ageing. Array of comprehensive mechanical properties examination and characterization in line with the appropriate specifications of the American Society for Testing and Materials Standard manuals were conducted to determine the influence of ageing on the material’s strength, hardness, impact toughness and stress-strain characteristics. The study revealed significant enhancement in the mechanical properties of the material and the findings would provide valuable insight into the ageing behaviour of Aluminium-Silicon, thus, enabling the optimization of the material’s performance for use in diverse engineering applications.

Influence of drying methods on tensile strength of polyester composites reinforced apus bamboo

In this research, the tensile strength of polyester composites reinforced with apus bamboo fiber (Gigantochloa apus/GA) was characterized. The bamboo fiber used does not contain lignin. The lignin removal process is greatly influenced by the chemical processing system and drying method. In this paper, the influence of three drying method systems (air drying, oven dring and freeze drying) on the physical properties of bamboo fiber reinforced polyester is studied comparatively. The matrix used is polyester resin BTQN 157. The volume fractions GA fiber are 15%; 20%; 25%; 30%. Specimens for tensile testing using the ASTM D638-03 Type I. The results of study drying method for GA fiber influences the tensile strength and modulus of elasticity of polyester composite material reinforced with GA fiber. The air drying method provides the greatest increase in tensile strength and Modulus of Elasticity and the freeze drying method is around 180% - 200%. Freeze drying method provides increased tensile strength and the lowest modulus of elasticity is around 4.5 - 5.0%.

Response of PLA material to 3D printing speeds: A comprehensive examination on mechanical properties and production quality

This study investigates the impact of printing speed on the mechanical properties of parts produced through the fused deposition modeling (FDM) method using a three-dimensional (3D) printer. Tensile test specimens, fabricated with Polylactic Acid (PLA) material on an Ender 3 S1 3D printer, were subjected to varying printing speeds from 15 mm/s to 105 mm/s in 15 mm/s increments, maintaining a 100% infill rate. Detailed measurements of sample masses, hardness values, and surface roughness were conducted to assess the potential effects of printing speed on PLA’s mechanical properties. Porosity values were also calculated to evaluate internal structure homogeneity and void ratios. The results indicate that an increase in printing speed leads to a substantial reduction in production time. For instance, at a speed of 15 mm/s, the printing time was 119 minutes, decreasing to 15 minutes at 105 mm/s. As speed increased, there was a tendency for a decrease in sample masses, with a notable 12% reduction from 8.21 grams at 15 mm/s to 7.21 grams at 105 mm/s. While lower speeds (15 and 30 mm/s) exhibited higher Shore D hardness values, an overall decrease in hardness was observed with increasing speed. Surface roughness showed a proportional increase with printing speed; for example, at 0° angle, the roughness value increased from 0.8 at 15 mm/s to 1.9 at 105 mm/s. Moreover, tensile strength values decreased with higher printing speeds. For samples printed at 15 mm/s, the tensile strength was 60 MPa, decreasing to 44 MPa at 105 mm/s, representing a 27% reduction. These numerical findings underscore the significant influence of 3D printing speed on both production efficiency and the mechanical properties of the printed material.

Multi‐objective optimization of 3D printing process parameters using gray‐based Taguchi for composite PLA parts

AbstractThis study investigates the additive manufacturing (AM) process of 30% ceramic‐reinforced composite PLA material using the fused deposition modeling (FDM) technique. The effects of various printing parameters on tensile strength, build time, and material consumption are comprehensively analyzed through a combination of the Taguchi method, analysis of variance (ANOVA), and gray relational analysis (GRA). Experimental design parameters include nozzle diameter, infill density, infill pattern, wall line count, print speed, and layer height. Statistical analyses reveal significant contributions of these parameters to mechanical properties and production efficiency. Single and multi‐objective optimizations of the responses were performed. The single optimization resulted in a significant increase in tensile strength from 39.9 to 48.10 MPa. Production time was reduced from 16 to 9 min; material consumption decreased from 4.95 to 2.43 g for tensile test specimens. The use of GRA in multi‐objective optimization has led to a significant improvement of 8.31% in the gray relational grade (GRG) when compared to the initial parameter settings. These findings provide valuable insights for optimizing FDM processes in the fabrication of composite PLA materials. This contributes towards the advancement of additive manufacturing technology and its applications across various industries. and its applications across various industries.Highlights Tensile strength increased while reducing build time and material consumption. Optimal printing parameters were identified for a composite PLA material. Layer height and nozzle diameter were effective parameters.

Functionalization of calcium-deficient nanohydroxyapatite improves the mechanical properties of 3D printed biopolymer nanocomposites

Agglomerations of nanoparticles in a polymer matrix can drastically reduce the mechanical properties of a polymer nanocomposite, especially its strength. The grafting of nanoparticle surfaces with suitable functional groups can provide improved dispersion and stronger interfacial bonding, improving the fracture resistance of the nanocomposite. In this study, calcium-deficient nanohydroxyapatite (nHA) particles were functionalized with an amino acid-based urethane methacrylate (lysine urethane methacrylate, LUM) and subsequently reacted with hydroxyethyl methacrylate. We mixed these functionalized nHA particles with resin, composed of methacrylated acrylated epoxidized soybean oil, methacrylated isosorbide, and triethylene glycol dimethacrylate, and 3D-printed nanocomposites using masked stereolithography. We hypothesized that the functionalized nanoparticles would enhance the mechanical performance of the 3D-printed nanocomposites due to the greater dispersion and stronger interface. Flexural, tensile, compression and Mode-I fracture toughness test specimens were fabricated using a mSLA printer and tested following ASTM standards. The LUM functionalization of nHA improved the dispersion and increased the viscosity of the uncured nanocomposite ink. The flexural fracture strength, yield strength, and mode-I fracture toughness values were increased by 10 %, 30 %, and 11 %, respectively. The LUM improved the strength and fracture toughness by providing a stronger, more stable interface, resisting debonding between the matrix and particles, allowing for greater plastic deformation.

The effect of mixing sequence on synthesis of PP-g-GMA compatibilizer for multilayer packaging (MLP) compounding

Melt recycling Multilayer Packaging (MLP) waste is difficult due to challenging separation procedures. However, blending techniques with compatibilizers can simplify MLP waste melt recycling. PP-g-GMA is a common compatibilizer in polyolefin and PET blends. PP-g-GMA compatibilizer was synthesized by utilizing an internal mixer at 175℃, 50 rpm, and 10 min using styrene as a comonomer. Titration was a method to examine effect of three different sequences of adding the BPO initiator on GMA grafting. Each sequence's PP-g-GMA samples were compounded with MLP waste using a twin-screw extruder and injection molded to make tensile test specimens. FTIR analysis shows that the GMA and Styrene monomers had grafted onto the PP polymer backbone, with the GMA grafting degree by varying mixing sequence. Sequence 3, which introduced initiator, GMA, and styrene simultaneously to PP melt, yielded PP-g-GMA with the most significant GMA grafting degree of 5.11%. Adding PP-g-GMA produced from sequence 3 into the MLP melt enhanced the highest increase in tensile strength and elongation at break of the MLP/PP-g-GMA compound.

Evaluating Impact of Different Parameters in Additive Manufacturing for Complex Situations

Additive manufacturing (AM) has emerged as an effective method for fabricating parts with internal complex features. However, optimizing process parameters to achieve desired mechanical properties for such complex geometries remains a challenge. This research aims to systematically evaluate the influence of AM process parameters on the tensile strength of PLA plus specimens containing a rectangular channel integrated inside the gauge section. A Taguchi L9 orthogonal design of experiments was formulated with four control factors - printing temperature, layer height, wall line count and infill percentage. Tensile testing specimen of standard ASTM D638-Type I containing a rectangular channel of 1.5x5x50mm was printed on an FDM machine. Tensile testing determined the ultimate tensile strength and percentage of elongation as the response. Signal- to-noise ratio analysis revealed optimized levels as 210°C, 0.20mm, 3 wall lines and 100% infill. Tensile testing of specimens printed at these conditions yielded average UTS of 34.58 MPa. Adopting Taguchi methodology, this study aims to improve understanding of interplay between key AM parameters and mechanical properties for PLA plus specimens with complex internal geometry. Optimized settings aid quality fabrication of functionally graded parts with intricate designs using this sustainable FDM material. Statistical design of experiments serves as an efficient evaluation approach. Key Words: Additive Manufacturing, Fused Deposition Modelling, PLA, Tensile Test Specimen

Study on low-temperature performance of silicone rubber for aerospace thermal control

Abstract Adhesive bonding technology is the primary method for installing thermal control products on spacecraft. Studying the bonding methods of electric heaters at low temperatures has become particularly important. To validate the feasibility of GD-414 silicone rubber in bonding electric heaters at low temperatures, GD-414 silicone rubber tensile test specimens were designed and fabricated. After thermal testing, it was found that the peel strength and failure mode of the specimens changed after low-temperature storage at -120℃ and temperature cycling from -200℃ to 40℃. The peel strength of the specimens improved after pressure treatment, while the differences in peel strength between different metal substrates with the same roughness were not significant. The research findings demonstrate that GD-414 retains strong bonding performance even after low-temperature storage and temperature cycling, making it suitable for bonding electric heaters.