Average Strength Values Research Articles

The effect of pulverized glass waste particle sizes on the mechanical properties of AA6061-T6 friction stir welded joints.

Abstract The study sought to investigate the effect of pulverized glass waste (PGW) particle size as reinforcement for AA6061-T6 joints produced by Friction Stir Welding. The study utilized three particle sizes of 15 microns, 45 microns and 75 microns of the PGW as reinforcement alongside the established process parameters ranges of 900-1400rpm, 25-63mm/min and 1-2.5° in a Taguchi L9 orthogonal array for the welding process experimental design. The welding experiments were repeated for each reinforcement particle size mentioned above. Parallel-hole reinforcement strategy was used on all joints for the application of the PGW, Tensile strength, Hardness tests and Microstructural Analysis were carried out on the welded joints and subsequently, analysis of the data. For tensile strength, several sample sets showed a trend of higher tensile strength the smaller the PGW particles size (Figure 6). For hardness, however, there was no overall, discernable trend/pattern of increase in hardness as the particle size decreased. The highest average tensile strength value obtained was 85.25MPa. The lowest tensile strength was 14.26MPa. A distinguishing feature between the highest and lowest value for tensile strength is that the former was obtained with a traverse speed of 25 mm/min while the latter was obtained using a 40 mm/min traverse speed. The higher the rotational speed of the tool pin, the greater the heat of friction generated while the lower the traverse/welding speed, the greater the heat of friction generated as the tool pin spends enough time per unit length to generate sufficient heat and cause plastic deformation sufficiently high enough to cause grain refinement. Using imageJ, percentage distribution of PGW for each crucial zone (Nugget/Stir zone, Thermo mechanically affected zone and Heat affected zone) of the FSWed joint was generated for samples selected for microstructural analysis. The average value for each sample was obtained as well. The highest tensile strength value (85.25MPa) was obtained with a sample using the smallest PGW size (15 µm), in line with the trend (figure 6) in which tensile strength was greater the smaller the PGW size used. The highest hardness value (90.90 BHN) was obtained with the sample having the highest average value for percentage distribution of the PGW (58.06%). A distinct trend was noted in which the greater the percentage distribution of the PGW, the higher the hardness value obtained (figure 30).

Joining of SiC ceramics by iridium: The interfacial phenomena and joint strength

A methodology for joining SiC ceramic parts using iridium foil was devised. The connecting layer was formed via a solid-state reaction at 1350 °C or via a transient liquid phase (TLP) at temperatures exceeding 1417 °C. The microstructure of the connecting layer formed via solid-state reaction exhibits temporal changes. The overall thickness of the layer remains approximately constant over time; however, the thickness of the carbon-free central part, composed of Ir and iridium silicides, decreases with time. The thicknesses of the porous carbon-containing sublayers located on either side of the central region demonstrate an increase. The greatest average flexural strength value was found to be 110 ± 6 MPa. The flexural strength values decrease with an increase in the holding time. This behavior can be attributed to the growth of a porous carbon-containing layer. The connecting layer, obtained via a transient liquid phase, is composed of IrSi and C. The layers on either side of the central dense IrSi part contain a number of pores and carbon inclusions. The SiC/SiC joints formed at 1425 °C and 1500 °C exhibit bending strengths of 66 ± 4 and 29 ± 4 MPa, respectively. These findings illustrate the potential of iridium to join monolithic SiC ceramic parts at relatively low temperatures.

Handgrip strength as a prognostic factor for COVID-19 mortality among older adult patients admitted to the intensive care unit (ICU): a comparison Alpha (B.1.1.7) and Delta (B.1.617.2) variants

Handgrip strength (HGS) is a non-invasive and reliable biomarker of overall health, physical function, mobility, and mortality. This study aimed to investigate the possible relationship between HGS and mortality in older adult patients hospitalized with COVID-19 in the intensive care unit (ICU) by Alpha (B.1.1.7) and Delta (B.1.617.2) variants. This retrospective cohort study was conducted on 472 COVID-19 patients (222 female and 250 male) aged 60–85 years admitted to the ICU. Demographic data, underlying comorbidities, COVID-19-related symptoms, as well as laboratory and computed tomography (CT) findings were obtained from the patient’s medical records. Using a JAMAR® hydraulic dynamometer, the average grip strength value (kg) after three measurements on the dominant side was recorded for subsequent analysis. Low grip strength (LGS) was defined as an arbitrary cut-off of two standard deviations below the gender-specific peak mean value of normative HGS in Iranian healthy population, i.e. < 26 kg in males and < 14 kg in females. The findings showed lower mean grip strength and high frequency of LGS in the non-survivors patients versus survivors group and in the Delta (B.1.617.2) variant vs. Alpha (B.1.1.7) variant, respectively (both p < 0.01). The binary logistic regression analysis showed that chronic obstructive pulmonary disease (COPD) (adjusted odds ratio [OR] 5.125, 95% CI 1.425–25.330), LGS (OR 4.805, 95% CI 1.624–10.776), SaO2 (OR − 3.501, 95% CI 2.452–1.268), C-reactive protein (CRP) level (OR 2.625, 95% CI 1.256–7.356), and age (OR 1.118, 95% CI 1.045–1.092) were found to be independent predictors for mortality of patients with Alpha (B.1.1.7) variant (all p < 0.05). However, only four independent predictors including COPD (OR 6.728, 95% CI 1.683–28.635), LGS (OR 5.405, 95% CI 1.461–11.768), SaO2 (OR − 4.120, 95% CI 2.924–1.428), and CRP level (OR 1.893, 95% CI 1.127–8.692) can be predicted the mortality of patients with Delta (B.1.617.2) variant (p < 0.05). Along with the well-known and common risk factors (i.e. COPD, CRP, and SaO2), handgrip strength can be a quick and low-cost prognostic tool in predicting chances of mortality in older adults who are afflicted with COVID-19 variants.

Safety evaluation of electromagnetic exposure for compact wireless charging stations of electric vehicles

ABSTRACT The spatial electromagnetic field of electric vehicle (EV) wireless charging stations may experience a superposition effect, which will increase the electromagnetic radiation. To assess the safety of electromagnetic exposure from wireless charging stations, this study employs a finite element simulation software to construct an electromagnetic environment model for a compact wireless charging station. The model is utilized to compute the superposition effect of spatial electromagnetic fields resulting from the simultaneous charging of multiple wireless chargers. Furthermore, the model assesses the levels of electromagnetic exposure on human models at eight observation points situated within the charging station. Results indicate that the volume average values of spatial magnetic induction strength ( B ) and electric field strength ( E ) are higher when multiple EVs are charged simultaneously than when a single EV is charged, and the electromagnetic radiation received by a human standing between two vehicles is greater than that near one vehicle. At the 22 kW charging power level, the maximum values of B , E and current density at the eight observation points of the charging station are all below the International Commission on Non-Ionizing Radiation Protection limit, demonstrating that the human body is safe in compact wireless charging stations at this power level.

Physical model case study: treatment effect of soft ground by vacuum preloading combined with liquid bag pressurization method

Vacuum preloading and composite ground reinforcement are commonly used methods for reinforcing soft soil, but there is a lack of integrated design method for vacuum preloading combined with composite ground. This case study introduces an innovative approach that combines vacuum preloading with liquid bag pressurization to achieve the integrated design of consolidation drainage method and composite ground reinforcement, which is different from the reported air bag pressurization. To illustrate the effectiveness of this method. Model tests were carried out to analyze the variation of water discharge, pore water pressure, ground settlement, and average consolidation degree in the process of vacuum consolidation. The study investigated the water content, undrained shear strength, and ground bearing capacity of composite ground after ground treatment. A correlation between average undrained shear strength and characteristic value of ground-bearing capacity was established to evaluate and predict the treatment effect of composite ground. Research shows that compared with traditional vacuum preloading, the undrained shear strength can be increased by 13.78%–65.08%, and the characteristic value of bearing capacity for the composite ground can be enlarged by 2.3–4 times. These results indicate that the vacuum preloading combined with liquid bag pressurization can significantly improve reinforcement effect on soft ground.

Investigation of Fiber-Matrix Interface Strength via Single-Fiber Pull-Out Test in 3D-Printed Thermoset Composites: A Simplified Methodology.

The emergence of additive manufacturing technologies for fiber-reinforced thermoset composites has greatly bolstered their utilization, particularly within the aerospace industry. However, the ability to precisely measure the interface strength between the fiber and thermoset matrix in additively manufactured composites has been constrained by the cumbersome nature of single-fiber pull-out experiments and the need for costly instrumentation. This study aims to introduce a novel methodology for conducting single-fiber pull-out tests aimed at quantifying interface shear strength in additively manufactured thermoset composites. Our findings substantiate the viability of this approach, showcasing successful fiber embedding within composite test specimens and precise characterization of fiber pull-out strength using a conventional mechanical testing system. The test outcome revealed an average interfacial strength value of 2.4 MPa between carbon fiber and the thermoset epoxy matrix, aligning with similar studies in the existing literature. The outcome of this study offers an affordable and versatile test methodology to revolutionize composite material fabrication for superior mechanical performance.

STUDY OF PHYSICAL PROPERTIES MECHANICAL PROPERTIES AND THE DEVELOPMENT OF PARTICLEBOARD FROMDURIAN PEEL USING A COMPRESSION MOLDING PROCESS

This research is the process study of producing particleboard from durian peel using the compression molding process. These studies are the physical and mechanical properties of particleboard from durian peel. The results found that the flexural test and the tensile test of furniture material sheets from durian peels at a ratio of durian pulp to glue water were 1:0.2, 1:0.4, 1:0.6, 1:0.8, 1:1, and 1:1.5, respectively. A specimen with dimensions of width 50 x length 200 x thickness 10 millimeters was tested with a machine. The universal testing machine of six samples in each ratio. It shows that the mechanical strength values increased when the ratio of water mixed with glue increased. The durian pulp has a better adhesion. This results are in a higher density as the ratio increases and at the ratio of 1:1.5, it has the highest strength and an average flexural strength of 5.74 MPa but it has not yet passed the criteria set by TISI 876-2004 with a flexural strength of not less than 14 MPa for plywood sheets with a thickness exceeding 6.0-13.0 millimeters. It has an average tensile strength value perpendicular to the surface of 0.49 MPa, which passes the criteria set by TISI standard, with the tensile strength value perpendicular to the surface not less MPa. than 0.40 for plywood with a thickness of more than 6.0-13.0 millimeters. For the testing of the burning rate of particleboard made from durian peels, it was found that the burning rate decreased when the ratio of water mixed with glue increased due to the increasing density of the workpiece at a ratio of 1:1.5 and it can stop the combustion by itself.

THE EFFECT OF ADDING WASTE TIRE RUBBER POWDER ON PAVING BLOCK WEAR

Pavement using paving blocks is the right choice because of its easy installation and maintenance. One form is a quadrilateral type that is widely used for environmental and pedestrian roads. With good road access being one of the improvements in vehicles so that waste tires also increase, solutions are needed to reduce the impact on the environment but are also expected to provide benefits for paving block roads, especially increasing adhesion between paving block constituent materials. Based on this background, it was a research idea with the aim of determining the effect of adding waste tire rubber powder on the wear resistance of paving blocks. Research method with strength testing on paving block samples with a size of 5 cm x 5 cm x 2 cm a total of 18 samples. The results showed the average strength value of paving blocks with a mixture of waste tire rubber of 1%, 2%, 3%, 4%, 5% of 0.134, 0.223.0235, 0.246 and 0.247 mm / minute, so that the addition of waste tire rubber powder showed a decrease in the wear rate of paving blocks.

THE EFFECT OF ANNEALING TEMPERATURE ON THE TENSILE STRENGTH OF POLYLACTIC ACID FILAMENT PRINTED BY 3D PRINTER

The development of the industrial world is getting faster from time to time. The manufacturing industry is one of the industries that is very developed, especially in the use of technology. Although there have been some studies on the tensile strength of PLA filaments however, it is not yet clear about the effect of annealing treatment on the tensile strength of PLA filaments from 3D printers. Therefore, this study was conducted to determine the effect of annealing temperature on the tensile strength of polylactic acid material printed by 3D printers. This research uses experimental methods with the following conditions: The filament used is polylactic acid (PLA), specimens are printed to ISO 527-2 standard and the annealing treatment temperature are 50⁰C and 70⁰C. From the results of testing and data analysis that has been carried out, it can be concluded that annealing treatment is quite influential on the tensile strength value of polylactic acid (PLA) materials. The greater the annealing temperature, the higher the tensile strength value. At 50⁰C annealing the average tensile strength value is 15.89 MPa, while at 70⁰C annealing the average tensile strength value is 16.66 MPa.

3D Chaotic Mixing Application for Polymer Production

Abstract Industrial mixing processes have attracted research over the last decade because rapid and effective mixing of the materials in a mixture is crucial for the production of novel materials. The method of mixing directly affects the physical and chemical properties of the resulting mixture. Different mixing processes have been developed to create a range of polymers with specific properties for&amp;#xD;applications such as tissue engineering, artificial muscles, and soft robots.&amp;#xD;The mixing process of RTV 2710 silicone rubber and Catalyst CX catalyst was carried out using the Halvorsen, Newton Leipnik, Hadley, and Sprott A. systems. Numerical values were obtained by solving chaotic differential equations. The speed of the DC motor that actuated the mixing propeller changed chaotically. To save energy, the energy values were measured and the Hadley-2 signal was found to be the least energy-consuming chaotic signal. SCARA tracked trajectories for all chaotic systems, samples were obtained, and tensile tests were carried out. The highest average values of force and average tensile strength were obtained in the Sprott A. chaotic system. Finally, samples with constant position and Hadley 2 velocity, and Sprott A. position and Hadley 2 velocity, were produced and subjected to a tensile test. As a result, the highest average force and average tensile strength results were obtained from the Sprott A. position and the Hadley 2 velocity.

Corrugated Structural Metal Decking System under Tensile Strength Test

Corrugated metal decking has been widely used in the construction industry for many years due to its benefits towards the sustainability, improve time performance of the projects and environmental aspects. This article includes the investigation of tensile strength and identify the failure behaviour of different corrugated surface profile of the metal decking that innovated for structural slab. Novelty of this research is the discovery of the tensile performance of a cold rolled corrugated metal decking profiles at various points of interest for a composite flooring system. Tensile strength specimen preparation complies with the ASTM E8 Standard. A total of 60 specimens with different thicknesses and different parts of metal deck have been tested by the universal testing machine (UTM). The findings on how Base Metal Thickness (BMT) affects the tensile strength and the unique roll formed of the corrugated metal decking system, with 0.75BMT & 1.00BMT, are discussed and analysed in this article. Results showed that the average tensile strength value for 0.75BMT and 1.00BMT from part A was 592.47MPa and 554.41MPa, respectively, and the metal decking is up to the designed strength and the unique roll forming embossment provides better bonding quality between concrete and steel to be used in the industry.

Pengaruh Media Pendingin Proses Laku Panas Terhadap Persebaran Butir Ferrite dan ketangguhan Mild Steel AISI 1020

This research aims to determine the toughness properties and microstructure of AISI 1020 steel material which was previously treated by using a variety of cooling media including air cooling, oil cooling and grease cooling. After being cooled by using several cooling media, it was continued with impact and microstructure testing. The results showed that AISI 1020 steel specimens using air cooling media, had the average impact strength value of 19.1 joules/mm, while those using oil cooling media had an average impact strength of 35.2 joules/mm, and those using grease cooling media had an impact strength of 45 joules/mm. From this data, the one with the highest impact strength value was the grease cooling media at 45 joules/mm and the one with the lowest impact strength was the air cooling media, namely 19.1 joules/mm. The results of metallographic observations were obtained when the grease media was used, the distribution of ferrite was reduced and did not have time to form, whereas in steel that was cooled with oil, the distribution of ferrite was almost the same as the untreated material and for air media, the shape of the ferrite structure spread and formed evenly.

Weathering and River Erosion: Insights from the Variation of Intact Rock Strength in Rhyodacites

The relationship between weathering and fluvial erosion is important in shaping the incisions of bedrock channels. In rhyodacites from Paraná Volcanic Province, plucking and macro-abrasion processes are predominant in the fluvial incision process, according to field observations. Using the intact rock strength as a proxy for the weathering, this paper analyzes how the strength of rhyodacites behave along a cross section of a bedrock channel and seeks to understand how this affects erosion. Topography and intact rock strength were surveyed continuously along a 30 m cross section using a Schmidt hammer, model N. Mean, median, and standard deviation were calculated for each meter of the section. The topographic amplitude of the bed in the section is 30 cm, featuring an almost flat geometry. The average strength values range from 30 to 59 R (7.65 to 58.15 MPa). Despite the small topographical amplitude, the general behavior of the rock strength follows the macrotopography of the bed, increasing in the high zones and decreasing in the low zones. The standard deviation, interpreted as directly proportional to the degree of weathering, follows the microtopography of the bed (amplitude ≈ 10 cm), being greater in low areas and smaller in high areas. This association between standard deviation of strength and microtopography reveals the seasonal variation of the water level in the channel, whereby higher moisture in low-lying areas intensifies the weathering of the rock. Weathering affects the density of rhyodacites in the area with a minimum reduction of 11.2% being calculated. This enhances the erosion processes by plucking and macroabrasion by reducing the intact rock strength. The susceptibility of the rhyodacites to weathering, despite the differences within the section, favors the maintenance of the rectangular geometry of the channel and shows how erosive processes are affected by the condition of the rock. The study revealed that the notion of decreasing the intact rock strength towards the banks associated with greater weathering in higher areas, cannot be generalized, as it depends on the geometry of the channel section, the lithological nature of the bed, and the frequency of flows.

ИССЛЕДОВАНИЕ ФИЗИКО-МЕХАНИЧЕСКИХ СВОЙСТВ КОМПОЗИТОВ С ПОЛИМЕРНОЙ ФАЗОЙ ПОЛИЛАКТИДА И КОСТРОЙ КОНОПЛИ

As a result of the study the indicators of key physical and mechanical properties and biodegradation potential of composites with polymer phase of polylactide and technical hemp shives were determined, the properties of composites based on polylactide with technical hemp shives and reference materials with wood flour were compared. It is established that composites with hemp shives demonstrate on the average higher values of density, Shore hardness and bending strength, as well as lower water absorption at higher values of the wetting angle. The stiffness of samples with hemp shives practically does not change when the filler content is increased up to 30 wt. %, and increases with further increase in the degree of filling. The impact toughness of composites with hemp shives significantly exceeds the parameters of analogs based on polylactide and wood flour. In addition, the increase in the content of hemp shives, in contrast to technical wood flour, has practically no negative effect on the impact toughness of composites. Introduction of wood flour into the composition of polylactide leads to a sharp increase in water absorption, while the water absorption of samples with hemp shives does not exceed 2% regardless of the degree of filling. Replacement of wood filler with hemp shives in the composition of the composite leads to a significant decrease in the mass loss index after aging in the active soil for 30 days. In general, composites with polylactide polymer phase and hemp shives are superior to analogs with wood flour in terms of physical and mechanical properties. Lower biodegradation potential can be both an advantage and a significant disadvantage for composites with technical hemp shives.

Optimization of Unsaturated Polyester Resin Matrix Composite Materials Reinforced Banana (Musa Balbisiana) Fronds Composition Towards Tensile Test

This study aims to find out how the physical and mechanical properties of banana tree frond fibers are strengthened by a polyester matrix with various variations of fiber fractions. The study began by making three types of specimens with differences in volume fractions, namely 6% fiber + 94% matrix, 9% fiber + 91% matrix and 12% fiber + 88% matrix with the hand lay – up method. The results of making composites are carried out physical properties testing in the form of density testing, water absorption and thick development and mechanical testing with tensile tests. The results of the physical properties test show that the average density value of each volume fraction variation is above the JIS A509 – 2003 standard. The water absorption value and the thick development of the three fraction variations are still below the maximum limit. While in mechanical properties testing, the highest tensile strength value was obtained at a volume fraction of 12% fiber + 88% matrix with an average tensile strength value of 37.28 MPa.

Fracture strength of cad-cam milled polyetheretherketone (PEEK) post-cores vs conventional post-cores; an in vitro study.

The aim of this study was to compare the fracture strength and fracture modes of post-cores produced with CAD-CAM from modified polyetheretherketone (PEEK) materials with other custom-produced post-cores. Sixty human mandibular first premolars with equal root sizes were used. The teeth were divided into six groups (n = 10), and root canal treatment was performed. The teeth were separated from the roots over 2 mm from the cemento-enamel junction. As a result of the decoronation process, a 1 mm wide shoulder line was obtained for all teeth. For the fracture strength test, 10 mm deep post spaces were created on the teeth with a 1.6 mm diameter driller. Post-core groups consisted: everStick®glass fiber post-core (Group GF), zirconia post-core (Group Z), metal (Cr-Co) post-core (Group M), PEEK post-core without filler (Group UP), PEEK post-core with 20% TiO2 Filler (Group TP), and post-core with 20% ceramic filler (Group CP). Following the application of posts to post spaces, copings were created and cemented on the samples. With the universal tester, a force was applied to the long axis of the tooth with a slope of 135°. The mean fracture strength (N) between the groups was statistically evaluated using one-way ANOVA, and pairwise mean differences were detected using post hoc Tukey's HSD test among the groups. According to the results of the statistical analysis, a significant difference was found between the groups in terms of mean fracture resistance (p <0.05). Group Z (409.34±45.72) was significantly higher than Group UP (286.64±37.79), CP (298.00±72.30), and TP (280.08±67.83). Group M (376.17±73.28) was significantly higher than Group UP (286.64±37.79) and Group TP (280.08±67.83). There were no statistically significant differences between the means of the other groups (p >0.05). Among all the groups, Group Z exhibited a higher prevalence of repairable failure modes, while the rest of the groups predominantly experienced irreparable failure modes. In our study, zirconia and metal post-core samples showed higher average fracture strength values than PEEK post-cores groups. Repairable failure modes were more common in the zirconia post-cores, whereas the opposite was observed in the other groups. Further experimental and clinical trial studies are needed before PEEK materials can be used as post materials in the clinic.

The effect of incorporating hydroxyapatite into Type II glass ionomer cement on flexural strength and the examination of fractured surfaces using scanning electron microscopy

Background: Glass ionomer cement (GIC) is widely recognized as the prevailing direct esthetic restorative material. In order for a restoration material to be considered effective, possess favorable physical and mechanical properties. Incorporating with hydroxyapatite (HA) can provide these properties. This research is to investigate the impact of integrating HA into GIC on the flexural strength and scanning electron microscopy (SEM) of the fractured surfaces. Methods: The study consisted of 28 samples of GIC, which are fabricated in the shape of rectangular prisms (25x2x2mm). The samples were divided into four groups n=7. Group 1 is a control group (GIC), Group 2 GIC+2%HA, group 3 GIC+2%HA, and GIC+4%HA. The flexural strength of the sample was evaluated by a Universal testing machine, followed by an examination of the fracture surface using SEM. Result: The Brown-Forsythe was used as data analysis to examine the flexural strength values across all groups, resulting in a statistically significant p-value of less than 0.05. The addition of HA does not result in a significant increase in the flexural strength value of the glass ionomer cement (GIC). The integration of microstructure based on scanning electron microscopy (SEM) pictures demonstrates improved visual quality following the incorporation of HA. Conclusion: The addition of HA to GIC did not result in a significant change in flexural strength compared to the control group. However, GIC group with 2% HA exhibited the highest average flexural strength value among all the groups

STATISTICAL EVALUATION OF MECHANICAL CHARACTERISTICS REINFORCEMENT OF CLASS A500С IN COILS

The paper presents the results of astatistical evaluation of the mechanical characteristics of reinforcement of class A500S in coils.The statistical evaluation was performed based on the results of tensile tests on 144 samples of 8 mm diameter rebar of A5000S class made of St3ps steel. The samples were taken from 8 coils of different batches of industrial production, 6 samples fromthe beginning, middle and end of each coil. During the tests, the main mechanical characteristics of A500C reinforcement were determined - yield strength (σТ), ultimate strength (σВ), ratio of ultimate strength to yield strength (σВ/σТ), relative elongation after rupture (δ5), state diagrams were drawn and the elastic modulus of the rebar (Es) was determined. The statistical evaluation was performed for each of the studied parameters (σТ, σВ,σВ/σТ, δ5) first separately for each skein for samples taken from the beginning, middle and end, then for all samples taken from the beginning, middle and end of all skeins, respectively, and finally forthe entire sample of 144 samples.According to the test data of samples from 8 coils, the yield strength of A500C reinforcement varied in the range of 532.80...631.10 MPa, the temporary resistance - 697.30...762.70 MPa, the relative elongation at break - 18.75...30.00 %, the ratioof temporary resistance to yield strength -1.185...1.344.No stable patterns of change in the mechanical characteristics of the reinforcement along the length of the coils were found. The difference between the average values of yield strength, temporary resistance, relative elongation, and the ratio of temporary resistance to yield strength along the length of the coils did not exceed 2 %.The values of the coefficients of variation and the range of the values of the corresponding mechanical characteristics of the samples taken from the beginning, middle and end of the coils were also close to each other.The yield strength of A500C rebar with a diameter of 8 mm in coils in this sample of samples was 0.9999, with a normalised value of 0.95. The coefficient of variation was 0.0328.For the established security of the calculated reinforcement resistance at the level of 0.998, the reliability factor for A500C class rebar with a diameter of 8 mm in coils was 1.109, which is less thanthe value of 1.15 accepted in the current regulatory documents.

Mechanical Evaluation of Geopolymer Mortars Derived from Gold Mining Tailings under Differents Atmospheres

In this work, geopolymeric mortars made from formal and informal gold mining tailings (Peru) were studied in order to analyze their durability and mechanical resistance in compression. The manufactured mortars were subjected to uniaxial compression tests in four atmosphere conditions: dry air (0% humidity), saline air (5% with sodium cholride), humid air (99% relative humidity) and normal air (with relative humidity at 25%). During the compression tests, the thermoresistance at room temperature (between 11), 200 °C and 500 °C were also evaluated. The results obtained were contrasted with the mechanical resistance of mortars made with conventional cement (Control). The real density and porosity of the different mortars studied were also evaluated, finding real density and porosity values of 2.42 g/cm3 and 19%, 2.62 g/cm3 and 32%; and 2.71 g/cm3 and 36% for conventional cement mortars (Control), tailings geopolymeric mortars from informal mining (GI) and tailings geopolymeric mortars from formal mining (GF), respectively. The mechanical results obtained show average values of maximum compressive strength of 86 MPa, 23 MPa and 19 MPa for Control mortars, GI mortars and GF mortars, respectively. It was also possible to appreciate that the geopolymeric mortars presented cracks, superficial efflorescence, affecting the mechanical resistance in humid and saline atmosphere conditions. The simulated climatic conditions, in which it could have a better mechanical behavior, is a normal atmosphere and dry air. Regarding the evaluation of thermoresistance, they were at a temperature of 500°C, which presented greater mechanical resistance.

Experimental investigations on microstructure and mechanical properties of wall structure of SS309L using wire-arc additive manufacturing

In present study, a wall structure of SS309L was constructed through Gas metal arc welding based Wire-arc additive manufacturing process. The wall structure of SS309L underwent investigation for microstructure and mechanical properties at three positions along the horizontal deposition direction. Mechanical assessments, including microhardness testing, impact testing, tensile testing, and fractography, were conducted at three positions of walls. Microstructure study has shown a fine granular structure in addition to colony of columnar dendrites in bottom section, a columnar dendrites in middle section, and a mix of dendritic structure with even coarser structures in top section. The mean microhardness values were observed to be 159 ± 4.21 HV, 162 ± 3.89 HV, and 168 ± 5.34 HV for the top, middle, and bottom sections, respectively. Results of impact testing for the wall structure indicated greater strength compared to wrought SS309L. The tensile strength of the built structure showed average values of yield strength, ultimate tensile strength, and elongation to be 409.33 ± 7.66 MPa, 556.66 ± 6.33 MPa, and 39.66 ± 2.33 %, respectively. In comparison, wrought 309 L steel typically exhibits tensile strengths in the range of 360–480 MPa for yield strength, 530–650 MPa for ultimate tensile strength, and 35–45 % elongation. Thus, the obtained tensile strength results for the wall structure fall within the range of tensile strength observed in wrought 309 L steel. Fractography of the tensile and impact specimens, as obtained through Scanning Electron Microscopy, revealed the superior ductility of the fabricated component. This study contributes valuable insights into the manufacturing of wall structure and their analysis regarding mechanical characteristics.