Mechanical Testing Of Samples Research Articles

Preparation of PMMA/SiO2 Composite Sheets for Tribological and Mechanical Tests

This paper aims to prepare PMMA sheets (Polymethyl methacrylate sheets) reinforced with SiO2 nanoparticles (Silicon oxide nanoparticles) to obtain samples for tribological and mechanical tests. PMMA reinforced sheets are prepared by three methods; dissolving, pressing, and casting. In the first method, the pure PMMA granules were dissolved with an organic solvent. The SiO2 nanoparticles were dispersed using a magnetic stirrer. Then, the solution was poured into a glassy mold. In the second method, pure PMMA powder was used, and SiO2 nanoparticles were dispersed using a nanoparticle disperser device; then, the mixture was placed in a metal mold and pressed by a thermo-hydraulic press. While in the third method, pure PMMA resin and hardener were used, and SiO2 nanoparticles were dispersed using an ultrasonic probe machine, and then the mixture was poured into a glassy mold. The three preparation results showed that the obtained sheets were free of bubbles and that their surfaces were of excellent smoothness and could be cut using a laser to obtain the samples required for tribological and mechanical tests such as tensile test, impact test, wear test, surface hardness test, surface roughness test, and scratch resistance test and others.

Comparison of mechanical properties of 3D-printed and compression-molded wood-polylactic acid (PLA) composites

Mechanical properties of materials obtained by compression-molding were compared with three-dimensional (3D) printed materials. Firstly, wood flour was added at different levels (0, 5, 10, and 20%) to polylactic acid (PLA) polymer to produce filaments. Then, mechanical test samples were printed from the produced filaments with a 3D printer. The produced filaments were made into pellets, and sheets were obtained by compression molding. According to the mechanical test results, it was observed that the tensile strength of the 3D-printed and compression-molded materials were close to each other, and the elasticity modulus of the compression-molded samples was higher than the 3D-printed samples. In the hardness comparison, the compression-molded specimens exhibited higher hardness values than the 3D-printed specimens. When the morphological properties of the materials were examined, it was seen that the cross-sections of the compression-molded materials were smooth and had less void than the 3D printed ones. The glass transition, crystallization, and melting temperatures of the materials did not change much with the processing methods. Only the 3D-printing process increased the crystallinity percentages.

Using the remnants of pomegranate peel particles to strengthen the bases of PMMA dentures

Polymethylmethacrylate (PMMA) resin was used as a basic material in this research with pomegranate peel particles with fractional masses ((0,5,10,15 ,20%,25 ,30 %) as a cementing material with a granular size of 45µm)). Samples for mechanical tests to study mechanical properties (bending, shock, thermal conductivity) and at laboratory temperature (27°C(. The results of mechanical tests represented by (bending, shock) showed that the best value obtained for the bending modulus is (67Mpa) at a mass fracture of 10%. Moreover, the best value for the shock resistance is (58kJ/m2) at 20% mass fracture, and the thermal conductivity property decreases to the lowest value (0.71W/m.c°) due to the increased reinforcement with pomegranate peels.

Influence of solvent volatilization time on the physical and mechanical properties of universal adhesive systems and on nanoleakage of the hybrid layer

The influence of solvent volatilization time on sorption, solubility, flexural strength, modules of elasticity and resilience of universal adhesive systems, and nanoleakage in the hybrid layer were evaluated. All-Bond Universal (ABU) and Scotchbond Universal (SBU) were used according to the manufacturers' recommendations and for double the recommended volatilization time. Samples for sorption, solubility and mechanical tests were prepared (n = 10). Adhesives were applied to the dentin surface (n = 4), and nanoleakage of the tooth/restoration interface after silver nitrate infiltration was observed using scanning electron microscope. The data were submitted to ANOVA and Tukey's test (α = 5%). ABU showed greater sorption in the manufacturer's volatilization time, while SBU showed no significant difference between the times. At both times, ABU showed greater sorption than SBU (p<0.0001). Solubility for both adhesives was higher in the time recommended by the manufacturer (p = 0.0316). Nanoleakage in the hybrid layer was observed for SBU in both solvent volatilization times; greater nanoleakage was observed for ABU when using the time recommended by the manufacturer. Modulus of elasticity was greater with double the volatilization time recommended by the manufacturers for both adhesive systems (p = 0.0246). No significant differences were observed in adhesive and volatilization time in the other properties (p>0.05). An increase in volatilization time reduced solubility and increased the modulus of elasticity for both adhesives, as well as reduced sorption and nanoleakage for the ABU, but had no influence on the flexural strength and resilience module. • Increasing the volatilization time reduced the solubility of the adhesive systems. • Increasing the volatilization time increased the modulus of elasticity. • Increasing the volatilization time decreased sorption for All Bond Universal. • Increasing the volatilization time decreased nanoleakage for All Bond Universal.

Determination of mechanical performance of glass fiber reinforced and elastomer filled polyamide 6 composites

In this study, the mechanical performances of neat Polyamide 6 (PA6) polymer, 20wt.% glass fiber reinforced PA6, and 8% SEBS elastomer with 20% glass fiber reinforced PA6 composite were investigated. Composite materials were first produced in the form of granules by using a twin-screw extruder. Later, mechanical test samples were molded, in accordance with the American Society of Testing Materials (ASTM) standards, using an injection molding technique. Mechanical parameters such as tensile strength, tensile modulus, elongation at break, impact strength, flexural strength, and flexural modulus were determined by tensile, impact, and bending tests. With the addition of 20wt.% glass fiber reinforcement to the PA6 polymer matrix, properties such as tensile strength, tensile modulus, flexural strength, and flexural modulus increased, while properties such as elongation at break and impact strength decreased. For the 20% glass fiber reinforced PA6 composite with 8% SEBS rubber additive, while the impact strength increased by 177%, other mechanical values decreased. The fractured surface microstructure images of the samples obtained from the tensile tests were examined using a scanning electron microscope.

Study into the effect of different energy sources on the structure and mechanical properties of EP693 nickel alloy weld joint

The paper provides the results of a study on the influence of welding types (laser, electron beam, and TIG welding) on the properties of a permanent connection made of an EP693 alloy of the Ni–Cr–W–Co–Mo system used in the production of gas turbine engine components and parts. EP367 filler wire of the Ni–Mo–Cr–Mn system was used to obtain a weld during laser and TIG welding. A comparative analysis of heating areas and power densities was performed for the welding types studied. It was established that TIG welding features by greater values of the heating area and power density in comparison with laser and electron beam welding. It was found that the type of welding affects the features of weld formation. For example, a weld is formed with the transition to knife fusion penetration in the weld root for electron beam welding, and in the form of an «hourglass» for laser welding. The analysis of the heat affected zone microstructure showed that the smallest grain size is formed during laser welding. The distribution of elements in the weld joint was analyzed. It was found that when welding with the use of filler wire, the Mo content increases and the W, Co, Al, and Ti content decreases in the weld and heat affected zone relative to the base metal. This determines the peculiarities of failure for samples obtained using the welding types studied. Samples obtained by TIG and laser welding broke along the heat affected zone on the weld reinforcement side. Samples obtained by electron beam welding broke along the weld. Mechanical tests of samples at room and elevated temperatures showed that samples obtained by laser and electron beam welding have the highest tensile strength.

Preliminary Study of the Rhenium Addition on the Structure and Mechanical Properties of Tungsten Heavy Alloy.

The results of structure and mechanical property investigations of tungsten heavy alloy (THA) with small additions of rhenium powder are presented. The material for the study was prepared using liquid phase sintering (LPS) of mixed and compacted powders in a hydrogen atmosphere. From the specimens, the samples for mechanical testing and structure investigations were prepared. It follows from the results of the microstructure observations and mechanical studies, that the addition of rhenium led to tungsten grain size decreasing and influencing the mechanical properties of W-Ni-Fe-Co base heavy alloy.

Characterizing the vibration-assisted printing of high viscosity clay material

A widely recognized problem observed in direct write (DW) additive manufacturing (AM) is the inability to print highly viscous materials, such as clay or viscous pastes with high solids content. In this work, an additive manufacturing technique, known as vibration-assisted printing (VAP), is characterized and evaluated for its ability to print highly viscous materials (> 10,000 Pa⋅s). After demonstrating the ability to print highly viscous materials with fine resolution (nozzle diameter = 500 μ m) and fast print speeds (≥ 4000 mm/min), various print characterization tests are completed to analyze the VAP process’ capabilities in terms of print resolution, layer consistency, corner turning, and minimum feature size, using a representative highly viscous material, polyvinyl chloride (PVC) modeling clay. Analysis of the characterization samples provided insights into which aspects of the material and process parameters need to be closely monitored to ensure accurate material deposition, a vital step towards producing functional components. Once print characterization was complete, mechanical test samples were printed and quasi-statically tested to give insights into how the VAP process affected the mechanical properties of the printed material. The mechanical properties of the VAP components were shown to be inferior when compared to the bulk properties of the material for this particular material system and notable dependencies on the print direction were observed.

Demonstration of a High-Throughput Tensile Testing Technique Using Femtosecond Laser-Fabricated Tensile Bars in AISI 316 and Additively Manufactured Grade 91 Steel

Femtosecond laser machining offers a fast, low damage route to fabricating features on the order of a few micrometers to millimeters. Within this broad application space, mechanical testing samples on this scale provides a combination of region selectivity and a bulk-like response. Use of such mechanical test specimens, however, is relatively unexplored compared to microscale and macroscale testing. The present study showcases the benefit of combining efficient specimen fabrication and testing on the mesoscale for extracting a more comprehensive picture of material mechanical properties. Moreover, a material with a complex and heterogeneous microstructure, additively manufactured grade 91, has also been studied to highlight the considerations needed and limitations of testing on this scale.

Investigating the Mechanical Behavior of 3D Printed PLA-Coco Coir Composites

It is quite amazing that the use of 3D printing techniques, especially the Fused Deposition Modelling (FDM) has delivered such significance in terms of cost reduction, time saver features where a different variety of thermoplastic and composite materials (Biodegradable and Non-biodegradable) are well developed. Different sectors have continually developed natural organic materials that are also both structurally composite in nature. Similarly, the use of different fibers that are abundantly accessible and considered as renewable resources which can be optionally combined with other biodegradable materials is a great challenge through the use of the FDM printing method. The study aims to determine the effect of different particle size and raster angle at a certain fiber concentration which could affect the mechanical properties of the composite by developing a printable composite filament made of Polylactic Acid (PLA) and Coco Coir materials using a filament maker and FDM printer. The composite filament was fabricated and optimized using a twin-screw extruder and 3D Devo Filament maker. 3D printing of samples for mechanical testing was conducted using three (3) raster angles (45o, 60o, and 75o) and various particle sizes of coco coir fiber reinforcement in the PLA matrix. Results showed that the &lt; 74μm particle size of the coco-coir exhibited a 24% and 175% increase in tensile strength and izod impact strength compared to the pure PLA at 60o and 75o raster angles, respectively. Likewise, the reinforcement of &lt;149μm particle size coco coir at 45o raster angle contributes to an increase of 4.8% flexural and 176% compressive strength compared to pure PLA. The study concludes that there is an improvement in the mechanical properties of the PLA-Coco Coir composite at a certain particle size and raster angle in 3D printing.

Accelerating Additive Design With Probabilistic Machine Learning

Abstract Additive manufacturing (AM) has been growing rapidly to transform industrial applications. However, the fundamental mechanism of AM has not been fully understood which resulted in low success rate of building. A remedy is to introduce surrogate modeling based on experimental dataset to assist additive design and increase design efficiency. As one of the first papers for predictive modeling of AM especially direct energy deposition (DED), this paper discusses a bidirectional modeling framework and its application to multiple DED benchmark designs including: (1) forward prediction with cross-validation, (2) global sensitivity analyses, (3) backward prediction and optimization, and (4) intelligent data addition. Approximately 1150 mechanical tensile test samples were extracted and tested with input variables from machine parameters, postprocess, and output variables from mechanical, microstructure, and physical properties.

Влияние микролегирования иттрием и гафнием на прочностные характеристики и морфологию карбидной фазы сплава ЖС3ДК-ВИ при замедленной кристаллизации

There are analyzed the melts of the ZhS3DK-VI alloy with different levels of strength characteristics and the factors influencing their reduction, differences in the macro and microstructure of the alloy, the effect of the crystallization rate when pouring the melt into hot and cold ceramic molds are determined. Since when casting parts, the level of properties is determined on separately cast samples, in the technology of manufacturing samples, the casting parameters of the corresponding part must be observed, and when increasing the strength characteristics due to changing technological parameters, it is imperative to consider the possibility of changing the technology of casting parts. However, for parts of complex configuration, cast from heat-resistant nickel alloys, it is often impossible to change the technology, therefore the only way to influence the properties of the material is to use microalloying with rare earth elements, for example, yttrium and hafnium. The introduction of these alloying elements in small amounts has a positive effect on factors that reduce the properties of the ZhS3DK-VI alloy, such as the unfavorable shape and topography of the carbide phase, or even slightly change the chemical composition of carbides. The article analyzes the effect of microalloying with hafnium and yttrium on the morphology and topography of the carbide phase; positive changes in the microstructure and strength characteristics at room temperature of the heat-resistant nickel alloy ZhS3DK-VI are noted. The technology of microalloying the melt has been developed to obtain satisfactory valuesof strength characteristics in tensile tests and impact toughness at room temperature. Microalloying the ZhS3DK-VI alloy with hafnium in a concentration of 0.15...0.25 % made it possible to increase the strength characteristics on samples for mechanical tests by 10…15 %, provided that the melt was drained into hot ceramic molds and slowed down. Higher concentrations of hafnium during slow crystallization lead to the formation of eutectic phases uncharacteristic for the ZhS3DK-VI alloy, requiring a decrease in the heat treatment temperature, which, accordingly, leads to a decrease in the level of long-term strength at 850 °C.

A printability assessment framework for fabricating low variability nickel-niobium parts using laser powder bed fusion additive manufacturing

PurposeThere is recent emphasis on designing new materials and alloys specifically for metal additive manufacturing (AM) processes, in contrast to AM of existing alloys that were developed for other traditional manufacturing methods involving considerably different physics. Process optimization to determine processing recipes for newly developed materials is expensive and time-consuming. The purpose of the current work is to use a systematic printability assessment framework developed by the co-authors to determine windows of processing parameters to print defect-free parts from a binary nickel-niobium alloy (NiNb5) using laser powder bed fusion (LPBF) metal AM.Design/methodology/approachThe printability assessment framework integrates analytical thermal modeling, uncertainty quantification and experimental characterization to determine processing windows for NiNb5 in an accelerated fashion. Test coupons and mechanical test samples were fabricated on a ProX 200 commercial LPBF system. A series of density, microstructure and mechanical property characterization was conducted to validate the proposed framework.FindingsNear fully-dense parts with more than 99% density were successfully printed using the proposed framework. Furthermore, the mechanical properties of as-printed parts showed low variability, good tensile strength of up to 662 MPa and tensile ductility 51% higher than what has been reported in the literature.Originality/valueAlthough many literature studies investigate process optimization for metal AM, there is a lack of a systematic printability assessment framework to determine manufacturing process parameters for newly designed AM materials in an accelerated fashion. Moreover, the majority of existing process optimization approaches involve either time- and cost-intensive experimental campaigns or require the use of proprietary computational materials codes. Through the use of a readily accessible analytical thermal model coupled with statistical calibration and uncertainty quantification techniques, the proposed framework achieves both efficiency and accessibility to the user. Furthermore, this study demonstrates that following this framework results in printed parts with low degrees of variability in their mechanical properties.

Cyclic Deformation of Microcantilevers Using In-Situ Micromanipulation

BackgroundThe trend in miniaturisation of structural components and continuous development of more advanced crystal plasticity models point towards the need for understanding cyclic properties of engineering materials at the microscale. Though the technology of focused ion beam milling enables the preparation of micron-sized samples for mechanical testing using nanoindenters, much of the focus has been on monotonic testing since the limited 1D motion of nanoindenters imposes restrictions on both sample preparation and cyclic testing.Objective/MethodsIn this work, we present an approach for cyclic microcantilever bending using a micromanipulator setup having three degrees of freedom, thereby offering more flexibility. ResultsThe method has been demonstrated and validated by cyclic bending of Alloy 718plus microcantilevers prepared on a bulk specimen. The experiments reveal that this method is reliable and produces results that are comparable to a nanoindenter setup.ConclusionsDue to the flexibility of the method, it offers straightforward testing of cantilevers manufactured at arbitrary position on bulk samples with fully reversed plastic deformation. Specific microstructural features, e.g., selected orientations, grain boundaries, phase boundaries etc., can therefore be easily targeted.

Preparation and Mounting of Whole Blood Clot Samples for Mechanical Testing.

Studying and quantifying the mechanics of blood clots is essential to better diagnosis and prognosis of, as well as therapy for, thromboembolic pathologies such as strokes, heart attacks, and pulmonary embolisms. Unfortunately, mechanically testing blood clots is complicated by their softness and fragility, thus making the use of classic mounting techniques, such as clamping, challenging. This is particularly true for mechanical testing under large deformation. Here, we describe protocols for creating in vitro blood clots and securely mounting these samples on mechanical test equipment. To this end, we line 3D-printed molds with a hook-and-loop fabric that, after coagulation, provides a secure interface between the sample and device mount. In summary, our molding and mounting protocols are ideal for performing large-deformation mechanical testing, with samples that can withstand substantial deformation without delaminating from the apparatus. © 2021 Wiley Periodicals LLC. Basic Protocol 1: Cube-shaped blood clot preparation Basic Protocol 2: Sheet-shaped blood clot preparation.

Influence of a Liquid on the Deformation Behavior of Porous Nickel and Titanium under Compression

The deformation behavior of capillary porous (CP) Ni and CP Ti is examined under uniaxial compression in air, water, and ethanol. CP metals contained inert liquids such as H20 and C2H5OH are used as the heat pipes’ active elements in space applications. The samples for mechanical testing were isostatic compacting and vacuum annealing (porosity of 60%). Uniaxial compression tests were carried out in the air, water, and ethanol in Shimadzu AG-50K XD (traverse rate 0.1 mm/min). It was shown that CP Ni and CP Ti exhibit the ductile deformation behavior in all cases, which is inherent to Ni and Ti. The ethanol environment induces the increase of the compression strength and the total deformation in both materials compared to deformation behavior in air and water. Therefore, a heat pipe’s failure containing CP Ni and CP Ti matrixes and ethanol as the working body is caused rather by manufacturing defects, but not the structural materials’ intrinsic properties.

Elastic constants of Chilean Pinus radiata using ultrasound

Elastic constants of Pinus radiata were determined using ultrasound technique. In parallel, typical compression mechanical testing was carried out to compare the effectiveness of the nondestructive test using ultrasound technique. The longitudinal elastic constant values were similar to the mechanical testing (ultrasound technique was 12,8 % higher than mechanical testing), showing that ultrasound technique is a reliable and valid tool. The values for radial and tangential moduli obtained by ultrasound technique versus mechanical testing showed more differences. This may be due to the difficulty in obtaining adequate samples for mechanical testing. The symmetry of the shear modulus was revealed by ultrasound technique (Gij = Gji). Poisson’s ratios were not comparable using either method; however, values obtained by ultrasound technique were more consistent with the existing literature for Pinus species. Additionally, the elastic anisotropy of the analyzed wood samples was demonstrated through ultrasound velocity propagation in the material. It was thus possible to obtain the twelve engineering constants that characterize the mechanical behavior of wood by means of the proposed ultrasound technique

Thermomechanical analysis of nitinol memory alloy behavior

Shape memory alloys are functional materials characterized by the effect of shape memory and superelasticity. Due to these properties, they are widely used, particularly, in bioengineering, aeronautics, robotics and civil engineering. The temperatures of phase transformations and the influence of external temperature and strain rate on the functional and mechanical characteristics of Ni55.75Ti44.15 shape memory alloy are investigated in this paper. The temperature of alloy phase transformations is obtained by differential scanning calorimetry (DSC) in the temperature range from -70°C to 70°C. Diagrams of differential scanning calorimeters at different heating and cooling rates of Ni55.75Ti44.15 alloy is constructed and analyzed. Samples for mechanical tests are made of round rod 8 mm in diameter. The samples working area is 12.5 mm in length and 4 mm in diameter. Mechanical tests are carried out at temperatures close to the maximum value of the completion temperature of martensitic-austenitic transformation Af = 14.7°C. Diagrams of deformation under uniaxial tension are constructed and stresses of phase transformations, Young's modulus and relative elongations of transformation areas at different loading speeds and exterior temperatures are determined. Using Clausius-Clapeyron formula, it is shown that with simultaneous changes in temperature and strain rate, the stresses of phase transformations are largely due to changes in temperature rather than load rates. The coefficients of Clausius-Clapeyron equation for superelastic Ni55.75Ti44.15 alloy with shape memory, which are consistent with those known in the literature, are determined.

Influence of rolling and annealing modes on properties of semi-finished sheet products made of aluminum deformable alloy 1580

The study covers the manufacturability and properties of sheet metal obtained from a large-sized ingot of Alloy 1580 with the low scandium content within its grade range. The ingot processability in hot and cold rolling was evaluated, and the influence of the degree of deformation and annealing conditions on the properties of cold-rolled semi-finished products made of the alloy under study was investigated. A large-sized commercially produced ingot with a cross section of 500×2100 mm of Alloy 1580 with a scandium content of 0.067 wt.% was selected as an object of research. The research methodology included several stages of rolling and heat treatment of semi-finished sheet products at various stages of the developed mode for metal deformation and mechanical testing of samples from them on the LFM 400 kN universal machine. For research, a 60×500×900 mm template was cut from the ingot to make 50×180×300 mm billets for rolling. Billets were subjected to homogenization annealing by the two-stage mode developed previously for this alloy. As a result of hot rolling of annealed billets at 450 °C and a total relative compression e Σ = 84÷90 %, 5–8 mm thick semi-finished sheet products were obtained. Further, after their annealing at t = 320 °C for 6 hours, light-gauge semi-finished sheet products with a thickness of 2 to 6 mm were manufactured by cold rolling. They were subjected to mechanical analysis in the deformed and annealed states. The analysis of their mechanical properties in the deformed and annealed states was performed, which showed that the accumulation of the total degree of deformation during cold rolling up to 38 % provides the 1580 alloy with an increase in strength properties to R p = 380 MPa, and after that the growth rate slows down and at e Σ = 60 % R p = = 400 MPa. The effect of annealing at temperatures between 250 °C and 350 °C on the mechanical properties of sheet metal. It was found that it leads to a decrease in strength properties and an increase in ductility, and the maximum yield strengths correspond to annealing temperatures of 250–275 °C at a sufficiently high plasticity. As a result of studies, it was found that the strength properties of sheet metal from Alloy 1580 with a low scandium content exceed the strength properties of semi-finished products of Alloy AW-5083 (USA) having a similar chemical composition, but without the addition of scandium, by 10–15 %, and the excess in plastic properties is 40–60 %.

Effect of Stirring on the Quality of ADC 12 Cast Aluminium Alloy

Stirring is one the most utilized process in small foundry. It is used for homogenizing the temperature and mixing process during melting. However, stirring may cause undesirable effect to the quality of castings if it is not managed properly. Bifilm is one of the defects that can be detrimental to the quality of aluminium castings, and its formation can be related to the stirring during melting. The research aim is to investigate the effect of stirring during melting of cast aluminium alloys. The quality of castings is approached by the term of bifilm index and mechanical properties. ADC 12 cast aluminium alloys is used in the experiment. The ADC 12 ingots are melted at 720 °C, and then stirred for 0, 3 and 5 minutes. Reduced Pressure Test is used for determining the bifilm index. Samples for mechanical testing are also casted into specific geometry. Results indicate that prolonged stirring time increases the bifilm index, indicating that more porosity and bifilm oxide are formed. Extended stirring time instigates more turbulence in liquid metal, hence surface oxides are folded and trapped in the bulk liquid metal. Charpy impact test, hardness test and tensile test have also carried out. More Porosity and bifilm oxide are formed in the samples and tend to decrease the mechanical property.