Mechanical Quality Research Articles

A Short Review on the Wire-Based Directed Energy Deposition of Metals: Mechanical and Microstructural Properties and Quality Enhancement

Wire-based directed energy deposition (WDED) is an emerging additive manufacturing process garnering significant attention due to its potential for fabricating metal components with tailored mechanical and microstructural properties. This study reviews the WDED process, focusing on fabrication techniques, mechanical behaviors, microstructural characteristics, and quality enhancement methods. Utilizing data from the Web of Science, the study identifies leading countries in WDED research and highlights a growing interest in the field, particularly in materials engineering. Stainless steel, titanium, aluminum, and copper-based alloys are prominent materials for WDED applications. Furthermore, the study explores post-processing techniques such as machining, heat treatment, and surface finishing as integral steps for quality enhancement in WDED components.

Artificial intelligence and machine learning for additive manufacturing composites toward enriching Metaverse technology

<p class="Abstract">As a result of the growing significance and application of technology across a wide range of fields, digital environments such as Metaverse started to take shape over the span of the previous decade. This study aims to discover an area of engineering that could benefit from this new technology by developing an artificial intelligence (AI)—based approach to analyzing and predicting the mechanical properties of carbon fiber reinforced syntactic thermoset composites that are made through additive manufacturing (AM). These composites are intended to be utilized as a tool for metaverse technology in a variety of domains—as the presence of the limitations in the currently experimental methods. The metaverse allows for the generation of simulations through the application of artificial intelligence (AI) and machine learning (ML). Consequently, this paves the way for individuals to investigate various design possibilities and view the virtual manifestation of those possibilities. This is made possible by the use of machine learning algorithms, which allow for the monitoring and evaluation of user performance, as well as the provision of individualized feedback and suggestions for improvement. As a consequence of this, it is feasible that professionals will be able to get education and training that are both more efficient and effective. Consequently, this work aims to introduce an Adaptive Neuro-Fuzzy Inference System (ANFIS)—based model, which is able to effectively anticipate the behavior of mechanical systems in a variety of settings without the need for significant measurements. The validity of the ANFIS model was determined through the utilization of flexure and compression testing. The approach that was used to improve the technical assessment of the manufactured composites—is verified by the model’s near-realistic predictions. Moreover, this method is superb for lowering weight, enhancing mechanical qualities, and minimizing product complexity.</p>

Synthesis and Characterization of Zirconia-Based Ceramics: A Comprehensive Exploration of Film Formation and Mixed Metal Oxide Nanoparticle Synthesis

Due to its strong ionic conductivity and superior mechanical qualities, zirconia-based ceramics are frequently used in electrochemical devices. Today, zirconium oxychloride octahydrate and ethanol have been developed for the purpose of reducing zirconium thin films on glass, single-crystal silicon p-type, substrates. The phase composition and properties of the films, as well as the physicochemical processes involved in film formation, have all been investigated. Zirconia mixed metal oxide nanoparticles with various physicochemical properties can be created using a variety of synthetic processes in conjunction with additional variables like concentration, PH, type of precursor utilized, etc. In order to create zirconia mixed metal oxide nanoparticles, many synthetic techniques, including sol-gel, hydrothermal, and coprecipitation methods are discussed in this article.

Sustainable innovations and future prospects in construction material: a review on natural fiber-reinforced cement composites.

There is a growing trend in the construction industry to adopt environmentally friendly practices, and innovative materials are becoming increasingly popular. Within the scope of this paper, the potential of natural fiber-reinforced cement composites (NFRCs) as an environmentally friendly building material is examined. This work introduces plant fiber aspects such as micromorphology, primary components, physical and mechanical properties, chemical components, thermal properties, and degradation mechanisms in cement composites. It explores how plant fibers affect concrete's mechanical performance, durability, and thermal qualities. It is responsible for increasing permeability and decreasing durability in concrete material because plant fibers have porosity and a weak interface. The purpose of this in-depth investigation is to investigate the features, sustainability (social, environmental, and economical) performance, and applications of NFRCs, with a particular focus on environmentally responsible innovation and potential future applications. The exhaustive study also addresses the difficulties associated with attaining the highest possible level of compatibility between fibers and matrixes. The physical and chemical treatments of natural fibers in cement components give more resistance to aging by reducing water absorption and increasing roughness at the surface. It is also possible to reduce the effect of alkalinity of the cement mixture through optimization of the binder component and curing regimes, which retard the breakdown of natural fibers. The purpose of this study is to present a summary of existing research, with a particular emphasis on the benefits, drawbacks, and prospective ways in which NFRCs could potentially improve throughout the construction industry in the future.

Effect of hot coil immersion cooling process on microstructure and properties of strip steel and oxide scales

ABSTRACT Coils obtained at the end of hot rolling of four different low carbon steels (DX54D, HX180YD, DX51D and HCT590X) were subjected to immersion in water for cooling (IC) as against the normal natural cooling (NC). IC produces significant improvements in the microstructure, scale formation, distribution of mechanical properties and surface quality. A model developed to simulate thermal history in the hot coil being cooled indicates that the 0.1°C/min core cooling rate in NC increased by over 7 times in IC, thereby decreasing the temper softening effects. Results of the tests performed exhibit a greater uniformity in the longitudinal properties and a 30–50% reduction in the band spread. The volume fraction of carbide on the DX54D steel is reduced by 20–30%, and the yield platform length is increased from 2.6 to 3.4%. The IC process was observed to significantly inhibit the formation of the banded structure in the HCT590X steel and the average yield strength of the coil increased by ∼30 MPa. The thickness of the oxide scale in all the steels decreased by 30–40% and the FeO content in the scale increased by 10–20%.

Correlating FDM Printing Parameters with Mechanical Properties and Surface Quality of PLA Printouts

Abstract This study explores the correlation between four critical Fused Deposition Modeling (FDM) parameters—extrusion temperature, layer height, print speed, and infill density—and the mechanical properties and surface quality of PLA (Polylactic Acid) printouts. The mechanical properties, including Young’s modulus, tensile strength, and bending strength, were evaluated alongside surface roughness and dimensional accuracy. The results indicate that extrusion temperatures between 200°C and 220°C optimize mechanical performance, enhancing tensile strength and bending strength, while smaller layer heights (0.1 mm) improve surface smoothness but increase print time. Moderate print speeds (around 60 mm/s) offer the best balance between strength and efficiency, while higher infill densities (above 80%) enhance mechanical properties, increasing both tensile and bending strength by up to 25%. These findings provide key insights into optimizing FDM printing parameters to achieve improved structural integrity and aesthetic quality in PLA prints.

Incorporating geranium plant waste into ultra-high performance concrete prepared with crumb rubber as fine aggregate in the presence of polypropylene fibers

Abstract This research examines the efficiency of ultra-high-performance concrete (UHPC) when utilizing geranium plant (GP) ash, which is subjected to different curing temperatures ranging from 300 to 900°C for 3 h of burning time. The GP ash is used as a replacement for cement in varying amounts (10, 20, 30, 40, and 50 wt%). Crumb rubber powder is utilized as a substitute for fine aggregate. Polypropylene fibers have been used to improve concrete performance. The performance of UHPC is evaluated by assessing its mechanical qualities, such as flexural strength, splitting tensile strength, and compressive strength. The sorptivity test is also evaluated as a component of it. Scanning electron microscopy is used to analyze UHPC after exposure to temperatures as high as 900°C. The findings demonstrated a notable enhancement in the mechanical characteristics of all mixtures. The most favorable mixtures were achieved with proportions of 50, 40, 40, and 20% for mixtures including GP waste incinerated at temperatures ranging from 300 to 900°C. Furthermore, the optimal outcome is achieved when 40% substitution is performed at a temperature of 700°C, resulting in notable enhancements of 14% in compressive strength, 30% in flexural strength, and 17% splitting tensile strength, respectively. At a high temperature of 700°C, the decrease in strength increased to approximately 37–40% as a result of the initial removal of carbon dioxide from calcite at temperatures ranging from 600 to 900°C and reached 56% at 900°C. Great resistance to sorptivity, as well as a dense and compact microstructure with a high content of calcium and silicon, was obtained.

Green Recycling of Carbon/Carbon Composites by Solid-State Shear Milling Technology as a Polyamide Multi-Functional Modifier

Carbon/carbon (C/C) composite materials are widely used in aerospace, the military and nuclear energy. The outstanding mechanical qualities of C/C composites mean that they are difficult to crush and recycle using traditional technology. The current recycling methods primarily involve stacking and landfill disposal. Therefore, achieving efficient and environmentally friendly recycling of carbon/carbon (C/C) composites is an urgent and challenging issue. In this work, we reported a simple high-value recycling approach for carbon–carbon frictional composite material (CFCM). The solid-state shear milling (S3M) technology is employed to achieve ultrafine milling of carbon matrices in carbon/carbon (C/C) composite materials while preserving carbon fibers. By this means, carbon fibers and the carbon matrix were mainly split, and the prepared composite powder had combined functionalities of conductivity, thermal conductivity, reinforcement, and wear resistance. The experimental results showed that the tensile strength of the material increased from 64.35 MPa to 72.79 MPa after being compounded with PA6, and the thermal conductivity increased from 0.211 W/mK to 0.611 W/mK. The friction coefficient was reduced from 0.51 to 0.36, a reduction of 25.4%, and the heat deflection temperature was increased from 47.2 °C to 108.2 °C. The S3M technique proposed in this work is an efficient, high-value, and scalable recycling strategy for CFCM, which can be used to produce value-added products and has great application prospects.

Antimicrobial Effect of Zinc Oxide Nanoparticle Coating on Titanium 6 Aluminum 4 Vanadium (Ti-6Al-4V)-Fixed Orthodontic Retainer Substrate

Abstract Objectives Due to its excellent biocompatibility, superior mechanical qualities, and exceptional corrosion resistance, titanium 6 aluminum 4 vanadium (Ti-6Al-4V) alloy is frequently used for medical and orthodontic purposes as a fixed retainer after active orthodontic treatment. Titanium lacks the antibacterial characteristics and is bioinert, this may influence the usage of such materials in the field of biomedical applications. Bacterial adhesion to the orthodontic retainer surface is a common first step in infection; this is followed by bacterial colonization ending with the formation of a biofilm. Once biofilm forms, it is highly resistant to medicines and the host immune system's defense mechanism, making it difficult to remove the biofilm from orthodontic retainer. This study aimed to test the antimicrobial effect of a zinc oxide (ZnO) nanoparticle coating on Ti-6Al-4V orthodontic retainers. Materials and Methods ZnO nanoparticles, with a particle size of 10 to 30 nm, were used to coat the alloy using the electrophoretic deposition method. Various parameters and surface characterization tests were employed to obtain an optimized sample. This sample was subjected to the microbial adherence optical density test to examine the adherence of Streptococcus mutans, Lactobacillus acidophilus bacteria, and Candida albicans. Results The optimized sample had a 5-mg/L ZnO concentration, applied voltage of 50 V, and a 1-cm distance between electrodes. The ZnO coating significantly reduced microbial adherence compared to uncoated samples, effectively inhibiting bacterial development. Conclusion Electrophoretic deposition is an efficient and cost-effective technique for coating orthodontic titanium retainer substrates. Coating Ti-6Al-4V with ZnO nanoparticles increased the antimicrobial effectiveness of the material and as the concentration of the nanoparticles rises, the antimicrobial effect increases too.

Improving thermal insulation and thermal resistance properties of laterite‐based geopolymer foams by direct foaming

AbstractThis work aims to synthesize new foaming laterite geopolymer foam using laterite, sodium silicate solution, sand, and aluminium powder. The porosity rapidly increased with the addition of the foaming agent. The foam matrix had thermal conductivity values of 0.10 W/m K with 0.7% of Al powder and 0.64 W/m K with 0% of Al powder. For fire resistance, samples exposed to high temperatures (200°C and 500°C) showed increased flexural strength, linear shrinkage at 500°C, and a decrease at 900°C due to structural weakening under high thermal pressure and the appearance of new phases such as nepheline and akermanite in X‐ray diffraction analysis. The results also showed that a 30% increase in fine aggregate content increased the strength of the foam matrix, with flexural strength ranging from 5 to 9.1 MPa after 28 days of ambient curing. These laterite geopolymer foams have shown promising thermal insulation and mechanical qualities that are appropriate for building applications.

Comparative analysis of the wear behaviour of TiN/TiAlN, TiAlVN, and TiAlYN coated tools in milling operations of Inconel 718

Abstract Milling is widely used in the aeronautical and aerospace industries, due to the possibility of producing parts with good dimensional stability and surface quality. Because of its exceptional mechanical qualities and limited thermal conductivity, Inconel 718 is a nickel superalloy that is regarded as a challenging material to process. Due to the flexibility of milling, this is the most commonly used process for machining INCONEL alloys. However, high levels of tool wear can be observed. Coatings can be deposited on the cutting tools to improve process performance. Nonetheless, doping elements such as yttrium and vanadium when added to TiAlN-based coatings can increase the coating's resistance. Furthermore, multilayer coatings tend to be very promising resistance to crack propagation. Thus, this work intends to compare three coatings deposited via PVD, in terms of the quality of the machined surface and wear resulting from the process: TiAlVN, TiAlYN, and TiN/TiAlN. The cutting speed (Vc), feed per tooth (fz), and cutting length (Lcut) were varied. It was possible to verify that the multilayer coating had better results, in terms of average roughness (Ra) and in measuring wear (VB3) and its characterisation. On the other hand, the TiAlVN coating showed the worst results. It was concluded that due to the TiN layer, the TiN/TiAlN coating has better resistance to crack propagation, as its adhesion to the substrate is good and there is no delamination.

Stress and Quality of Life of Parents of Children With POLR3-Related Leukodystrophy: A Cross-Sectional Pilot Study.

Background: RNA polymerase III (POLR3)-related leukodystrophy is a rare, neurodegenerative disorder characterized by hypomyelination, hypodontia, and hypogonadotropic hypogonadism. Despite the challenges of caring for a child with POLR3-related leukodystrophy, few studies have examined parents' disease burden. We sought to investigate quality of life and stress levels amongst parents of children with POLR3-related leukodystrophy. Methods: 43 parents of 32 children completed questionnaires on demographics, stress, quality of life, coping mechanisms, and experience of injustice. Detailed clinical data was collected from all patients. Results: Mothers (t[27] = -8.66, P < .001) and fathers (t[16] = -4.47, P < .001) had lower quality of life scores compared to the normative population, yet 80% of parents' stress scores fell within the normal stress range. Parents' experience of injustice scores were high (>60). Correlations were found between and within parents' scores. Years since disease onset and certain life circumstances correlated to mothers' quality of life scores; however, no correlation was found between modifiable factors and fathers' quality of life scores. Helpful coping mechanisms included those that allowed parents to be involved in their child's life. Conclusions: This is the first study to assess stress and quality of life in this population. These results shed light on the importance of implementing services and social support to improve the well-being of parents.

Inductive Frequency-Coded Sensor for Non-Destructive Structural Strain Monitoring of Composite Materials

Structural composite materials have gained significant appeal because of their ability to be customized for specific mechanical qualities for various applications, including avionics, wind turbines, transportation, and medical equipment. Therefore, there is a growing demand for effective and non-invasive structural health monitoring (SHM) devices to supervise the integrity of materials. This work introduces a novel sensor design, consisting of three spiral resonators optimized to operate at distinct frequencies and excited by a feeding strip line, capable of performing non-destructive structural strain monitoring via frequency coding. The initial discussion focuses on the analytical modeling of the sensor, which is based on a circuital approach. A numerical test case is developed to operate across the frequency range of 100 to 400 MHz, selected to achieve a balance between penetration depth and the sensitivity of the system. The encouraging findings from electromagnetic full-wave simulations have been confirmed by experimental measurements conducted on printed circuit board (PCB) prototypes embedded in a fiberglass-based composite sample. The sensor shows exceptional sensitivity and cost-effectiveness, and may be easily integrated into composite layers due to its minimal cabling requirements and extremely small profile. The particular frequency-coded configuration enables the suggested sensor to accurately detect and distinguish various structural deformations based on their severity and location.

The Role of Mechanical Mixing and Biologically Active Additives in Enhancing Cutlet Quality

The research relevance is determined by the need to understand the effect of mechanical mixing and the use of biologically active additives on the quality of cutlet mass, which will optimize food technologies and create products with improved texture and nutritional value. This need stems from the fact that the quality and characteristics of culinary products are important criteria for consumers. The research aims to investigate the relationship between mechanical mixing parameters and the use of biologically active additives with structural and mechanical quality parameters of cutlet mass, to improve production processes and develop higher quality food products. Analytical methods, classification methods, functional methods, statistical methods, and synthesis methods were used to determine the quality of the cutlet mass. In the course of the study, a comprehensive analysis of the effect of various parameters of mechanical mixing and the use of various biologically active additives on the structural and mechanical characteristics of the cutlet mass was carried out. It was found that optimal mixing conditions and types of additional components can significantly improve the textural properties of the product. It was found that the use of certain biologically active additives helps to increase the resistance of the mass to mechanical stress and preserve its juiciness. These conclusions allow us to develop more effective strategies for the production of cutlet mass with improved quality and nutritional value. The practical significance of this study is to provide scientifically based recommendations for optimizing food production processes aimed at improving the quality and nutritional value of cutlet mass by studying the effect of mechanical mixing and biologically active additives on its structural and mechanical properties.

Recyclable cellulose-based vitrimer electrolytes for lithium ion batteries

Cellulose as polymer electrolytes in lithium-ion batteries (LIBs) has a number of advantages such as low cost, readily available, abundant, environmentally friendly, and contains electron-donating groups within its structure. Beside, vitrimers are a novel class of polymer materials made of dynamic covalent networks that can undergo bond-exchange processes. Beyond cellulose's special qualities, cellulose-based vitrimer production is highly desired for enhancing electrolytes mechanical qualities, thermal stability, cyclability, and ionic conductivity. In this study, cellulose-based vitrimeric polymer electrolytes are prepared. At first, poly(glycidyl methacrylate-co-methyl acrylate) by different ratios of comonomers is prepared and then cellulose is cross-linked by prepared copolymers. Prepared vitrimers are recycled four steps through transesterification reaction and as-prepared and recycled crosslinked celluloses are used as gel polymer electrolytes (GPEs). The results showed the best ionic conductivity of as-prepared samples in order of 10−4 S/cm whereas ionic conductivity increased to order of 10−3 S/cm for recycled samples. Also, high lithium-ion transfer number of >0.8 was achieved for recycled samples. All as-prepared and recycled electrolytes had excellent electrochemical stability window (> 5 V). Also, improved specific capacity (>178 mA h g−1 with capacity retention upper than 90 % after 200 cycles at 0.2C of LiCoO2/GPEs/Gr) was attained.

Comparative estimation of fracture resistance of teeth restored with new fiber impregnated composite, short fiber composite, and nanohybrid composite – An in-vitro study

INTRODUCTION. Composite resins, used in restorative dentistry, offer enhanced esthetic and mechanical qualities. Nevertheless, the significant issue of volumetric shrinkage during polymerization remains a concern. Shrinkage-induced stress has the potential to cause marginal defects and enamel and cuspal fractures, especially in high stress-bearing areas. The present study aimed at assessing and comparing the fracture resistance and fracture patterns of teeth restored with new impregnated cubical composite, short fiber reinforced composite, and nanohybrid composite in mesio-occlusal-distal (MOD) cavities.MATERIALS AND METHODS. This was an in-vitro study comprising 45 extracted premolars cleaned and mounted in resin blocks. The MOD cavities were prepared in all the samples and were divided into three groups; Group I samples restored using ESPE Filtek Z350 XT restorative composite syringeTM, Group II using GC EverX posterior compositeTM (4mm), and Group III using Fibrafill cube S. Restorations were finished and polished.RESULTS. The mean fracture resistance was 844.5±264.8, 1249.7±518.3, and 1240.8±453.3 in Group I, II, and III, respectively. Group II and III fracture resistance was comparable (p=1.00) but higher than Group I (p=0.03 with Group II, p = 0.04 with Group III). No significant difference was present in the favourable and nonfavourable fracture patterns between the three groups (p=0.108).CONCLUSIONS. Short fiber and cubic fiber integrated composites performed similarly in terms of fracture resistance resulting in favourable fracture, however better over conventional nanohybrid composites.

A comparative investigation of neutron and gamma radiation interaction properties of zircaloy-2 and zircaloy-4 with consideration of mechanical properties

Abstract This study has established the radiation shielding efficacy of zircaloy-2 and zircaloy-4 over a wide spectrum of energy levels. Using the Monte Carlo N-Particle (MCNP) method, the gamma and neutron transmission factors (TF and nTF) were calculated for various energy levels. Zircaloy-2 demonstrated the highest gamma-ray absorption capacity and the lowest neutron absorption capacity among the investigated alloys. The results indicate that zircaloy-2 and zircaloy-4 have nearly the same neutron transmission characteristics. Although many studies have examined the structure and physical characteristics of these materials, there has been a lack of Monte Carlo simulations to comprehensively investigate the correlation between gamma absorption, neutron absorption parameters, and mechanical qualities. This research aims to examine the ability of zirconium and its zircaloy-2 and zircaloy-4 alloys, which are critical materials used in the nuclear industry, to absorb gamma and neutron radiation over a broad spectrum of frequencies. According to the results, zircaloy-2 has the best ability to absorb secondary gamma rays and the highest level of resistance to them. Despite the minimal disparity in the nTF between the two alloys, simulation results have shown that zircaloy-2 has a higher level of neutron transmittance. These results have the potential to expedite the development of novel materials with enhanced attributes for various applications.

Investigation on effects of nano-reinforcement on the mechanical properties, fatigue, and microstructural analysis of dissimilar AA6061- Mg AZ31B weld joints

Weld joints have been subject to substantial improvement in mechanical durability and wear resistance in recent years. This research work challenge can be answered by incorporating nano-materials into the weld zone. Mechanical and metallurgical aspects of friction stir welded (FSW) butt joints made of AA6061 aluminum and Mg AZ31B alloys have been examined in this work, both with and without the use of naturally derived biochar nanoparticles. The biochar particle was extracted from rice husk. Throughout the whole weld joint manufacturing process, a tool with a rotational speed of 1400 rpm, a welding speed of 40 mm min−1, and a tapered pin profiled tool were employed. During the joint fabrication process, the constant axial load of 7 kN, plunge depth of 0.2 mm, and constant dwell time of 0.3 s were also maintained. In order to improve the mechanical attributes of the weld joints, different wt% of biochar such as 1%, 2%, and 3%, were applied at the interface region of the weld joints. The experimental results revealed that the percentage of reinforced nano-materials plays a significant effect in improving the weld joint qualities. The testing results of reinforced friction stir-welded joint qualities were compared to those of simple friction stir welded joints made without and with adding the nanoparticles. The best results were obtained when 2 wt% of biochar particles was added to the weld interface region. The presence of biochar nano-particles, in addition to their contribution to increased grain refinement in the weld nugget region, was also seen in the region. It was discovered that the event distribution of particles at the nugget zone significantly enhanced the mechanical and wear resistance qualities of the weld joints that were manufactured. The optical microscope was used to analyze the microstructures in the weld nugget region, and a scanning electron microscope (SEM) was utilized to examine the fracture analysis of the tensile samples. The presence of 2 wt% biochar particles in the weld nugget region resulted in a considerable increase in the mechanical characteristics of the weld connections. The ultimate tensile strength, hardness, and yield strength of the weld nugget results 197 MPa, 173 HV, 163 MPa. Overall, when compared to the qualities of the base material and plain weld joints. The mechanical properties and wear resistance of the weld joints have improved significantly. When biochar particles were used as reinforcement particles during the fabrication phase of the joint, a mechanism for pinning was observed in the weld microstructure.

A Study on the Green Laser Weldability of Copper-aluminum Battery Materials

Copper is widely utilized in electric vehicle batteries due to its excellent electrical conductivity, lightweight, and excellent corrosion resistance. However, copper has a high reflectivity of about 97% for infrared lasers, which makes it difficult to achieve stable welding quality. This study investigated using a green laser to weld nickel-coated copper and aluminum materials. After performing welding by changing the laser power and scan speed, the weld cross-section was observed with an optical microscope, and it was confirmed that the welding penetration depth and bead width increased as the heat input increased. The spatter on the bead surface and defects such as pores and cracks in the weld were caused by excessive heat input. Analysis of the weld cross-section using SEM-EDS showed that high heat input increased the formation of intermetallic compounds including CuAl2 and Cu9Al4. The mechanical properties of the weld were examined using a shear tensile test. The analysis results showed that intermetallic compounds caused brittleness in the weld joint, which lowered mechanical properties and caused defects such as pores and cracks. P60 (1.2 kW, scan speed: 250 mm/s), P80 (1.6 kW, scan speed: 375 mm/s), and P100 (1.2 kW, scan speed: 375 mm/s) were examples of excellent mechanical quality. The fastest welding condition, P100 (power: 2 kW, scan speed: 450 mm/s), was suggested as the most efficient welding condition.

Experimental and theoretical study on axial compression behaviour of the modular combined column

Between the modular units of the modular steel building, there exists a combination of the adjacent modular columns. Due to the gaps between the modular columns and the lack of horizontal connections, the integrity of the modular steel structure is weak, which limits the use of modular steel structures in high-rise buildings. This paper proposes a kind of modular combined column realized the connection of modular single columns through the connectors and concrete, which can improve the integrity of the modular steel building. The assembly process of this new modular combined column is described. For axial compressive performance tests, four modular combined column specimens were designed, each with different height or different number of connecting plates. The axial compressive bearing capacity, ductility, stiffness, and other mechanical parameters of the specimens were analyzed according to the phenomena and load-displacement curves of the test. Then, the axial compression failure mode of the modular combined column specimens is compared and analyzed in conjunction with the finite element model. The results indicate that the axial compressive performance and ductility of the combined column suggested in this research are exceptional. The connector can enhance the overall mechanical qualities of the combined column by augmenting the restraining impact of concrete. Finally, the theoretical equation of the axial compression bearing capacity of the modular combined column is obtained by employing the superposition principle, and the equation's reliability is confirmed, along with the test results and the results of the numerical analysis.