Mechanical Characteristics Research Articles

The Effect of Post Weld Heat Treatment in Multi Layer Welding on Tensile Strength and Hardness

Post weld heat treatment is heating objects in the furnace to certain temperatures and times after the object has been welded. PWHT is expected to reduce residual stress on objects due to the welding process. In this case, we warm up annealing (holding in a furnace) at a temperature of 750 °C with a heating time of 40 minutes. We use MIG welding (metal inert gas) and a metal filler FS 705-6 with a diameter of 0.8 mm, with a total of 3 layers. First, the object will be formed according to the standard and welded in three layers with MIG welding. Then, the object will be cut and formed according to the tensile test standards, after which the tensile test and hardness test will test it to determine the mechanical characteristics of the object. From the testing that has been carried out, it is known that objects without PWHT have a higher stress and hardness value than objects with PWHT, with a stress value of 346.57 MPa and the highest hardness value of 93.5 HRB at the 3rd welding point. However, objects with PWHT have higher elasticity and strain values, with an elasticity value of 3.32 MPa, and the strain value of objects with PWHT is 13.1.

Effect of rolling texture on bearing capacity of aircraft repair patches and replaced panels

The article combines issues related to biaxial fatigue loading, corrections for equivalent stress calculations, and the practical application of new knowledge regarding biaxial fatigue in the aviation industry. It considers the possibility and expediency of taking into account the anisotropy of metals’ mechanical characteristics in aircraft repair procedures, such as patching and replacing damaged skin panels. The biaxial loading of the skin is shown to be a significant factor that should be considered in the aircraft skin repair process. It is shown that while well-known Huber-Mises formula works well for isotropic materials, the fuselage skin made of anisotropic alloys requires corrections to the Huber-Mises method. For aircraft parts subjected to biaxial loading, the assessment of equivalent uniaxial stresses can be done by introducing the crystallographic factor into the Huber-Mises formula. This is achieved by transforming the biaxial stress components of fuselage loading due to pressurization and bending into the resolved stresses in the activated crystallographic slip systems of the dominant texture.

Determination of heat input impact on residual stress, microstructural phase transformation and mechanical characteristics of welded S690QL steel joints by Taguchi optimisation approach

ABSTRACT This article focuses on optimising the submerged arc welding process to improve the microstructural and mechanical characteristics of welded S690QL steel joints efficiently without preheating, using a Taguchi optimisation approach. Trail runs were performed initially for bead-on-plate studies to optimise the weld cycle ranges by investigating weld characteristics such as microstructural morphology and toughness in the weld zone. Selected weld cycle ranges from bead-on-plate studies were further analysed and optimised through butt weld investigations. The phase transformations in microstructure at the weld and heat-affected zone from tempered martensite, martensite, and bainite to dendritic ferrite, lath bainite, and lath martensitic phase were observed with a change in heat input from 0.91 kJ/mm to 1.37 kJ/mm. The weld residual stresses were tensile at the weld and compressive away from the weld zone, diminishing gradually with an increase in transverse distance from the weld. The overall weld efficiency, weld residual stress concentration and mechanical characteristics of the welded butt joint were improved at a controlled heat input of 1.19 kJ/mm. An increase in heat input beyond the optimised limits influences the extent of the heat-affected zone and the joint’s toughness due to the coarsening of the weld microstructure towards the fusion boundary.

Mechanical Properties of Entirely Cement-Replacement Fly Ash-Based Geopolymers (G-SIFCON) and Cement-Based SIFCON: A Comparison Study

Environmentally friendly building materials known as geopolymers are made by combining high-alkalinity solutions with powder components rich in silica and alumina. It has long been known that adding fibers to the matrix phase can improve the mechanical characteristics of composite materials made for various uses. Among these are SIFCON composites, which are made by first inserting the fibers into the mold and then packing the gaps between the fibers with an extremely fluid matrix phase. The present study looked over the mechanical properties and efficiency of cement-based and geopolymer-based slurry infiltrated fiber concrete SIFCON and G-SIFCON. In the current study, for the production of both SIFCON and G-SIFCON composites, 7.5% steel fiber by volume fraction was utilized for this purpose. Therefore, sets of concrete specimens including cylinders and prisms were prepared and tested in accordance with standard specifications. The results obtained from the conducted tests prove that the 7.5% of steel fiber ratio can be used effectively to improve the mechanical performance of G-SIFCON and SIFCON composites. Furthermore, the cement-based SIFCON can be effectively replaced by fly ash-based geopolymers. Also, for composites made with fly ash-based geopolymers (G-SIFCON), high compressive strength slurries may exhibit more enhancement in mechanical properties than normal strength slurries.

INFLUENCE OF ADDITIVE MANUFACTURING TECHNOLOGY OF TOPOLOGICALLY OPTIMIZED PRODUCTS FROM PHOTOPOLYMER RESINS ON THE ANISOTROPY OF THEIR MECHANICAL PROPERTIES

This article discusses the problem of ensuring strength and minimum mass in the design of products manufactured using additive technologies. The authors investigated the possibility of using topological optimization in computer-aided design systems to create an optimized model with the necessary strength at a minimum weight. As part of the work, the topological optimization of the bracket, the production of its samples by additive manufacturing methods and strength tests were carried out. The optimal values were found via finite element analysis using the SolidWorks and ANSYS software. The calculation results show that the optimized model retains about 20% of the original mass and has the necessary mechanical characteristics. In particular, the excess safety margin is reduced by 2.5 times, which is acceptable for this bracket. The subsequent verification of the models is carried out through destruction tests of the products manufactured using additive technologies, i.e. the method of filament deposition and stereolithography. To account for the anisotropy of the material, a series of samples oriented at different angles to the direction of construction was made. The tests were carried out on a test bench for simultaneous biaxial stretching, which corresponds to the design loads on the bracket. An increase in the tensile load on the sample was carried out before its destruction. In the course of the work, the presence of anisotropy of mechanical properties was revealed, and optimization results in various software packages were studied. The results of strength tests allow us to draw two conclusions. Firstly, due to the anisotropy of the material, the strength properties significantly depend on the orientation of the bracket during additive manufacturing. Secondly, the bracket, optimized by means of the SolidWorks software package, generally showed the best strength properties for various orientations during manufacturing. Also, which is quite expected, the samples obtained by stereolithography showed less anisotropy than the samples obtained by the method of filament deposition. In conclusion, it is noted that the use of additive technologies to create optimized forms requires considering printing technologies and anisotropy of properties, as well as the choice of appropriate software.

Composite Structure MgB2@KNO3 With Multi-Effect Synergies to Improve Combustion Performance and Energy Release of B

ABSTRACT With the deepening of research, boron compounds have gradually gained favor among researchers due to their high calorific value and excellent ignition and combustion performance. In this paper, MgB2@KNO3, which exhibits excellent ignition and combustion properties, was synthesized using ultrasonic dispersion and magnetic stirring. The improved ignition mechanism and energy release characteristics of MgB2@KNO3 were elucidated using DSC/TG, SEM, EDS, XRD, and optical characterization, in conjunction with computational results from NASA-CEA. The surface activation energy and ignition energy of MgB2@KNO3 are 35.7% and 25%, respectively, lower than those of conventional B/KNO3 mixtures. Compared to the mixed sample of B/KNO3, the heat release of MgB2@KNO3 increased by 72.4%. The synergistic and effective interactions between oxygen, magnesium vapor, and boron in MgB2@KNO3 systems result in efficient energy release performance, making MgB2@KNO3 a promising material for use as a high-energy fuel in propellants, explosives, and pyrotechnic products.

Thermoplastic Composite Hot-Melt Adhesives with Metallic Nano-Particles for Reversible Bonding Techniques Utilizing Microwave Energy

This study investigated the creation of nano-composites using recycled LDPE and added 7.5 wt% nanofillers of Al and Fe in two varying particle sizes to be used as hot-melt adhesives for reversible bonding processes with the use of microwave technology. Reversible bonding relates to circular economy enhancement practices, like repair, refurbishment, replacement, or renovation. The physical–chemical, mechanical, and dielectric characteristics were considered to determine the impact of particle size and metal type. Through the investigation of electromagnetic radiation absorption in the composites, it was discovered that the optimal bonding technique could potentially involve a frequency of 915 MHz and a power level of 850 × 103 W/kg, resulting in an efficient process lasting 0.5 min. It was ultimately proven that the newly created hot-melt adhesive formulas can be entirely recycled and repurposed for similar bonding needs.

Partial Replacement of Coarse Aggregate with EPS Beads

The rising for natural aggregates in construction has caused resource exhaustion and environmental issues, prompting the search for sustainable options. This research explores the substitution of coarse aggregates with Expanded Polystyrene (EPS) beads in concrete, with the goal of tackling issues related to aggregate shortages and the management of EPS waste. EPS beads, recognized for their light weight, thermal insulation capabilities, and moisture resistance, provide possible advantages for the creation of lightweight and environmentally friendly concrete. The study assesses how different volumes of EPS beads as a replacement impact the physical and mechanical characteristics of concrete, such as density, workability, compressive strength, and durability. Experimental findings indicate that raising the EPS bead content decreases the self-weight of concrete and improves thermal insulation, although it negatively affects compressive strength. An optimal replacement ratio achieves a balance between structural performance and sustainability, rendering EPS-concrete appropriate for non-load-bearing structures, lightweight construction, and thermal insulation uses. The Compressive strength of 5%, 10% EPS based concretes compared to control concrete.This research shows the viability of utilizing EPS beads as a partial substitute for coarse aggregates, promoting sustainable construction methods and lessening environmental effects. The results offer important perspectives on the mix design and real-world uses of EPS-concrete, promoting its use as an eco-friendly option in the construction sector. KEYWORDS: Exhaustion, workability, expanded polystyrene, durability, thermal insulation.

Mechanical Performance and Tribological Behavior of WC-ZrO2 Composites with Different Content of Graphene Oxide Fabricated by Spark Plasma Sintering

This paper presents research on the effects of the addition of various contents of graphene oxide and sintering temperature on the mechanical, tribological, and electrical characteristics of WC-ZrO2 composites. Wet processing and spark plasma sintering provided dense samples with simultaneous reduction of graphene oxide (rGO) during sintering. The obtained results showed that the best mechanical properties were observed at a sintering temperature of 1700 °C in samples with 0.5 vol.% rGO content; namely, indentation fracture toughness (5.8 ± 0.4 MPa·m1/2) and flexural strength (872 ± 43 MPa) increased by 9% and 24.3% compared with the sample without rGO. In addition to improved mechanical performance, rGO-reinforced composites exhibited lower wear rates and friction coefficients than non-rGO composites, due to the formation of a graphitic lubricating tribolayer on worn surfaces and counterbodies in a friction pair, which provided sufficient lubrication to reduce the coefficient of friction and wear rate. The resulting composites also showed low electrical resistivity, suggesting the possibility of using electrical discharge machining to manufacture ceramic products of complex shapes from them.

After Foreign Body Ingestion: Waiting is not Always Disastrous

Background: Foreign bodies are objects with both organic and inorganic nature which originate from outside the human body. Due to ingestion, the gastrointestinal tract has become more prone mostly affecting paediatrics as compared to the adult population. Children with gastro-intestinal abnormalities including stenotic lesions and a history of Tracheoesophageal fistula are at increased risk of both occurrence and complications. The type, size, chemical properties of the object and the site of lodgment; all determine the clinical presentations. A history surrounding the circumstances, clinical presentations and radiological investigations are the pillars for diagnosis formulation. Besides the expectant and minimally invasive treatments, invasive modalities can also be employed especially in the presence of complications. Case presentation: A 3-year-old boy was brought to our hospital with a history of retching, hyper-salivation and inability to tolerate oral feeding as preceded by circumstances pointing towards gastrointestinal foreign body ingestion. An X-ray was suggestive of a gastrointestinal circular radio-opaque foreign body more likely at the level of duodenum in keeping with the coin. As he had no mechanical obstructive features, expectant management was done of which four days later he had a simultaneous passage of a 200 Tanzanian shilling’s coin on defecation. Conclusion: Early diagnosis, determining the surrounding circumstances and type of the foreign body ingested are the cornerstones for management modalities and outcomes. Both minimal and invasive approaches can be used, but the power of watchful waiting should not be underestimated as it can well be guided by the nature of the objects and the patient’s clinical presentations

Influence of water saturation on mechanical characteristics and fracture evolution of coal rock assemblage with rough interfaces

To comprehensively investigate the influence of water content on the mechanical and crack propagation characteristics of coal rock assemblage (CRA) with a rough interface, uniaxial compression tests were conducted on specimens with varying water content. Nuclear magnetic resonance (NMR) and acoustic emission (AE) techniques were employed to monitor the water content and AE signals throughout the experiment. The physical and mechanical properties, as well as the extent of crack development and acoustic emission (AE) parameters, were comprehensively investigated under conditions of water erosion. The results demonstrate that a rough interface contributes to an enhancement in the compressive strength of the composite material. Moreover, the moisture content exerts a significant influence on various aspects of the composite specimen, including its compressive strength, time b value, crack development, and crack propagation. With the increase in water content, the initial single slope shear failure of the composite specimen gradually transitions into a multi-section shear failure mechanism. Under the influence of water-rock interaction, sandstone within the formation undergoes a metamorphosis from a densely cemented structure to an irregular honeycomb-like configuration. This transformative process engenders novel porosity and fractures, ultimately compromising the rock’s mechanical strength. The analysis focuses on the relationship between the AE parameter b and uniaxial stress and water content, with emphasis on its relevance to damage theory. A damage model based on water immersion rate was established to elucidate the correlation between damage variables and water content. This was achieved by considering the characteristics of water-rock coupling AE and constructing a structural model of the water absorption process in different pore throats, thereby providing valuable insights for stability design and evaluation of roadway rock masses.

Effect of Alumina Proportion on the Microstructure and Technical and Mechanical Characteristics of Zirconia-Based Porous Ceramics

The current study investigates the process of preparing and analysing porous-structured ceramics made from zirconium, aluminium, and magnesium ceramic oxides. The starch consolidation casting (SCC) technique, with different types of starches (potato and tapioca), was used for this purpose. Our objective was to methodically examine the impact of different processing factors, such as the temperature at which pre-sintering and sintering occur, and the proportions of ceramic powders, on the microstructure, mechanical characteristics, and porosity of the resultant composites. Pre-sintering effectively reduced the rate of shrinkage during the final sintering stage; this resulted in more controlled and predictable shrinkage, leading to better dimensional stability and reduced risk of defects in the final product. A higher alumina content was associated with an increase in apparent porosity and a reduction in volume shrinkage and apparent densities. The mercury intrusion porosimetry (MIP) findings concluded that the prepared porous ceramics have a multi-modal pore structure. The highest calculated compressive strength was 76.89 MPa for a sample with a porous structure, which was manufactured using 20 wt.% tapioca starch and 30 wt.% alumina content. The main advantage of alumina is its ability to improve compressive strength by refining the grain structure and serving as a barrier against fracture development.

Ceramic composite materials based on the MAX phase Ti3SiC2 obtained by SHS extrusion

Compact cylindrical rods 220 mm long and 4 mm in diameter, consisting of a ceramic composite material based on the MAX phase Ti3SiC2, strengthened by TiC and TiB2 particles, were obtained during the combustion of the initial components (titanium, silicon, soot and boron) in the SHS mode followed by high-temperature deformation. These conditions were implemented in the SHS extrusion method. The influence of the initial composition on the structure, phase composition and mechanical characteristics (nanohardness, elastic modulus, bending strength) of the resulting materials has been established. It has been established that the formation of the Ti3SiC2 MAX phase occurs at the boundary with the TiC phase due to the diffusion of silicon under the influence of high temperatures (up to 1980‒2125 °C) accompanying the SHS extrusion process.

Cryo-Rolled AA5052 Alloy: Insights into Mechanical Properties, Formability, and Microstructure

Industries operating in extreme conditions demand materials with exceptional strength, fatigue resistance, corrosion resistance, and formability. While AA5052 alloy is widely used in such industries due to its high fatigue strength and corrosion resistance, its strength frequently falls short of stringent standards. For AA5052 alloy, this study explores the combined use of solutionizing and cryo-rolling, followed by annealing, to improve strength. Although several alloys have been reported to undergo solution treatment before cryo-rolling, this study focuses on how post-processing via annealing can lessen the formability constraints usually connected to conventional cryo-rolling. The study sheds light on the ways that solutionizing, cryo-rolling, and annealing interact to affect the alloy’s mechanical characteristics. Microstructure analysis shows that solutionizing improves the grain structure by reducing dynamic recovery, promoting dislocation density, and facilitating precipitate formation. Sheets subjected to solutionizing + cryo-rolling and partially annealed at 250 °C produce optimal results. Interestingly, formability is decreased when cryo-rolling alone is used instead of cold rolling, whereas formability is successfully increased when solutionizing is used. Comparing solutionized + cryo-rolled sheets that are partially annealed at 250 °C to cold-rolled sheets that are annealed at the same temperature, the former show notable quantitative improvements: a notable 17% increase in ultimate strength, a 10% boost in yield strength, and a noteworthy 13% enhancement in microhardness. Formability has improved with the solutionized + cryo-rolled specimens by annealing. This proposed approach led to noticeable gains in formability, hardness, and strength, which would significantly improve material performance for industrial applications.

Tribological and mechanical characteristics of glass/flax fiber-ZnO reinforced epoxy hybrid composite

Tribological and mechanical characteristics of glass/flax fiber-ZnO reinforced epoxy hybrid composite

Granular metamaterials with dynamic bond reconfiguration.

Biological materials dynamically reconfigure their underlying structures in response to stimuli, achieving adaptability and multifunctionality. Conversely, mechanical metamaterials have fixed interunit connections that restrict adaptability and reconfiguration. This study introduces granular metamaterials composed of discrete bimaterial structured particles that transition between assembled and unassembled states through mechanical compression and thermal stimuli. These materials enable dynamic bond reconfiguration, allowing reversible bond breaking and formation, similar to natural systems. Leveraging their discrete nature, these materials can adaptively reconfigure their shape and respond dynamically to varying conditions. Our investigations reveal that these granular metamaterials can substantially alter their mechanical properties, like compression, shearing, and bending, offering tunable mechanical characteristics across different states. Furthermore, they exhibit collective behaviors like directional movement, object capture, transportation, and gap crossing, showcasing their potential for reprogrammable functionalities. This work highlights the dynamic reconfigurability and robust adaptability of granular metamaterials, expanding their potential in responsive architecture and autonomous robotics.

Max-phase Ti3SiC2 and diverse nanoparticle reinforcements for enhancement of the mechanical, dynamic, and microstructural properties of AA5083 aluminum alloy via FSP

Abstract This study investigated the effects of max-phase Ti₃SiC₂ and other nanoparticle reinforcements (graphene, CNTs, and SiN) on the mechanical and dynamic properties of friction stir processed (FSPed) AA5083 aluminum composites. Microstructural analysis revealed the impact of these reinforcements on grain size. Dynamic properties were assessed using a free vibration impact test, while mechanical properties were measured through a compression test. Most composites showed enhancements in damping ratio and natural frequency compared to the base alloy, with the Ti₃SiC₂ leading to a substantial increase in natural frequency. The AA5083/max phase Ti3SiC2 composite demonstrated the most significant improvements across nearly all properties, notably enhancing stiffness (+7.35% in E), strength (+25.36% in yield strength), and vibration resistance (+5.83% in fₙ), while significantly reducing damping (−62.76% in ζ). In contrast, the friction stirred AA5083 offered moderate enhancements in strength (+17.86% in yield strength) and a slight increase in natural frequency (+2.00%) but did not significantly improve stiffness and actually increased damping. The base alloy AA5083 served as the baseline for comparison, exhibiting the lowest performance in all categories. The findings highlight the potential of FSP and reinforcement, especially Ti3SiC2, for tailoring the properties of AA5083 for enhanced performance in various applications. These findings emphasize the significance of customizing the reinforcement material to attain the intended mechanical characteristics in AA5083 composites.

Analysis and comparative studies of different thin orthotropic plates

The orthotropic materials are of a great importance and interest in the field of the modern industrial technologies’ applications such as: mechanics, aeronautics, civil engineering and biomechanics due to their hardness, their lightness and their super elasticity. During their working operation and under the effect of the external efforts, these materials can be submitted to cracks or ruptures which can cause disaster of their structure. In order to avoid these types of problems, the analysis of these materials is necessary in order to predict their mechanical characteristics and thus to augment their lifespan. This analysis is based essentially on the internal structure of material, its geometry, its boundary conditions and the external applied conditions. Our work consists of the analysis of the static and dynamic behavior of thin orthotropic bi- dimensional plates under the effect of external efforts using the numerical methods and of modulating based on the finite element methods. The strain and stress in any node of the orthotropic plate have been found for various types of loading (random and harmonic), with and without damping comparatively with those of an isotropic plate of the same dimension. And good effectiveness and reliabilities of the mechanical properties of the orthotropic plate were observed compared to those of orthotropic one.

Muscle-Fiber Typology Is Associated With Sprint-Cycling Characteristics in World-Class and Elite Track Cyclists.

Identifying the determinants of performance is fundamental to talent identification and individualizing training prescription. Consequently, the aim of this study was to determine whether estimated muscle typology is associated with the key mechanical characteristics of track sprint cycling. Sixteen world-class and elite track cyclists (n = 7 female) completed a laboratory session wherein torque-cadence and power-cadence profiles were constructed to determine maximal power output (Pmax), optimal cadence (Fopt), and maximal cadence (Fmax), and fatigue rate per pedal stroke was determined during a 15-second maximal sprint at Fopt. Muscle typology was estimated by measuring carnosine content via proton magnetic resonance spectroscopy in the gastrocnemius and soleus. Using partial correlation analysis to account for sex, greater muscle carnosine content (ie,greater estimated proportion of type II fibers) was associated with a greater Pmax (r = .68, P = .007), Fmax (r = .77, P = .0014), Fopt (r = .61, P = .0196), and absolute fatigue rate (W·stroke-1; r = -.55, P = .0418) but not relative fatigue rate (%peak power·stroke-1; r = -.33, P = .246). The findings from this study substantiate the mechanical differences in muscle-fiber types derived from single muscle-fiber studies and highlight the importance of estimated muscle typology for sprint cycling performance.

Molecular dynamics study on the effect of ferrite structure on the mechanical characteristics of pearlite

Molecular dynamics study on the effect of ferrite structure on the mechanical characteristics of pearlite