Papers by Keyword: Fatigue Resistance

Abstract: This study investigates the microstructural and mechanical integrity of the interface between Wire Arc Additive Manufactured (WAAM) carbon steel (CS) and an S355 structural steel (Wrought CS) plate, with emphasis on the suitability of WAAM for repair and reinforcement of structural components. A wall structure was deposited on a Wrought CS plate using a Cold Metal Transfer (CMT) process and subsequently characterized through microstructural analysis, hardness measurements, tensile testing, and bending fatigue testing. The microstructural observations revealed a smooth and defect-free transition across the interface, consisting of a fine-grained heat-affected zone (HAZ) formed by partial recrystallization. The hardness profile exhibited a continuous gradient, with slightly elevated values near the interface (~210 HV), indicating grain refinement and the absence of softening effects. The tensile results showed that the WAAM-deposited CS possessed higher strength and ductility than the Wrought CS, while the hybrid WAAM CS–Wrought CS specimens displayed intermediate properties. Fracture consistently occurred within the Wrought CS plate rather than at the interface, confirming a metallurgically sound and mechanically robust bond. Under bending fatigue loading, the WAAM CS demonstrated the highest fatigue limit (~250 MPa), followed by the hybrid (~205 MPa) and Wrought CS (~162 MPa). All hybrid specimens fractured on the Wrought CS side, indicating that the interface remained intact under cyclic stress.

Abstract: This review paper focuses on the major factors of deterioration, specifically rutting, stripping, and moisture effects, which are key factors affecting road pavements globally. Stressing the need to tackle these distresses, the study aims to improve the performance of asphaltic courses via advancing bio-based reinforcement materials, especially sisal fiber. The paper tries to analyze the mechanism of rutting in asphalt mixtures with a special reference to sisal fibers as an agent to increase resistance to permanent deformation. However, fiber reinforcement with the asphalt mixtures are also briefly described in the subject with the favorable effects of tensile strength, fatigue strength and crack propagation strength. The review further focuses on the ability of fiber reinforcement to enhance pavement service life, address pavement deterioration issues, and improving the service life of road pavements.

Abstract: In today's changing times, more and more people will use automobiles to get around, and this will consume a lot of natural resources to supply cars, in order to make energy efficiency, reducing the overall weight of the automobile is a direct way to reduce the weight of the automobile, and we need to use materials that can make the weight lighter while maintaining a certain level of strength. This review paper explores the properties of five custom materials: aluminum alloys, magnesium alloys, titanium alloys, carbon fiber, and ceramics. By comparing specific strengths and fatigue resistance, researchers found that customizing aluminum alloy are the most suitable materials for improving energy efficiency and reducing total vehicle weight, while still maintaining a certain level of stiffness. According to the data on the specific strength and fatigue resistance of aluminum alloy, it reaches conclusion that custom aluminum alloys can be used in the design of automotive vehicles as a function of improving fuel efficiency by reducing weight.

Abstract: This study presents a comprehensive exploration of the fatigue resistance of wire arc additive manufacturing (WAAM) carbon steel for lattice structures. Microstructural analysis unveils substantial grain dimensions characterized by a distinctive crystallographic configuration. These grains exhibit equiaxed characteristics, demonstrating uniform dimensions in all directions. The prevailing microstructure is dominated by ferrite grains. In tandem with the microstructural insights, hardness evaluations were conducted in correspondence with the part's deposition direction. The analysis of these measurements unveiled a consistent base material hardness of approximately 159 HV. The uniform distribution of hardness profiles supports the deduction that WAAM carbon steel uniformly embodies strength attributes. This congruence aligns harmoniously with the uniform microstructure evident in microscopic analyses. The yield strength of the WAAM carbon steel exhibits higher values in the build direction, peaking at 392 MPa. The bending fatigue tests revealed a fatigue limit approximating 180 MPa for WAAM carbon steel, evident in both the build and deposition directions. Fatigue strength of WAAM carbon steel mirrors that observed for reference material S355MC steel sheet.

Abstract: The wire arc additive manufacturing (WAAM) technology has become very popular recently. However, the properties of printed pieces are not yet examined properly. In this paper the effect of severe shot peening (SSP) on mechanical properties of wire arc additive manufactured AISI 316L is investigated. The effect of SSP on the surface hardness of the WAAM 316L is investigated by performing microhardness measurements. Changes to the surface microstructure caused by SSP are evaluated in the EBSD investigation. The effects of SSP on tensile and fatigue strength are investigated experimentally. The EBSD analysis showed that there has been remelting of each printed layer due to the heat input from the next printed layer, and heavy epitaxial grain growth was present in the microstructure. This led to coarse columnar grain structure. Investigation of deformed SSP surface layer indicated that the main deformation type was either conventional dislocation glide or twinning. This meant that no martensite formation was present on the surface. The SSP increased the surface hardness of WAAM printed 316L by 225% and the hardened layer was 0.4 mm thick. The SSP improved the yield strength of WAAM 316L by 34%. The SSP significantly improved WAAM 316L fatigue resistance in both low-cycle and high-cycle regime.

Abstract: Weight reduction is often a key factor in modern mechanical design, therefore materials such as carbon fibre reinforced plastics (CFRP) are increasingly used and integrated within multi-material structures using adhesive technologies, which require high effort and are difficult to disassemble. The capability of a blind rivet nut (BRN) to join different materials without these disadvantages has created a growing industrial interest in the fastener. However, installing a BRN in CFRP laminate induces a significant stress concentration in the plate, which potentially causes damage. Given that ‘damage free’ joints are demanded by the industry, the BRN is often not considered as a suitable joining technique. In the present research, an experimental campaign is performed to investigate the fatigue resistance of a BRN joint in CFRP. It is demonstrated that the resulting compressive stress after installing a BRN can enhance the fatigue resistance of the specimen. The results increase the potential of the BRN as a fastener for CFRP.

Abstract: Poor fatigue life is a huge issue of additively manufactured parts, despite the unique qualities characterizing this manufacturing process (such as low waste of material and geometry freedom). Fatigue life is strongly affected by both surface defects and internal defects, metal AM is characterized by extremely poor surface quality, internal porosities and lack of fusions. For this reason, many researchers investigated methods to improve manufacts quality. The most promising methods are surface finishing treatments and thermal treatments which provide an enhancement of fatigue behavior. A focal point of the research should be evaluating the respective contribution of surface treatments and thermal treatments. In order to evaluate the effectiveness of surface treatment, it is necessary to highlight the surface quality contribution in terms of fatigue life thus a specific testing method is necessary. Rotating beam fatigue test fits this requirement because each point of the specimen’s surface is subjected to the maximum stress. The aim of this work is to present the experimental setup for rotating beam fatigue testing that has been used to evaluate the fatigue behavior of AM SLM IN718 specimens.

Abstract: The main objective of this work is to study the fatigue behavior of photochromic textiles under different UV irradiance times and develop a rapid testing method. When considering their possible applications, the fatigue resistance of photochromic materials has been considered. The photochromic woven fabric was prepared using the screen-printing method. Previous studies have demonstrated the sensitivity of photochromic pigments to UV radiation's intensity during the experiment. This work provides different thoughts in testing the fatigue resistance of spiro-indolines-based pigment applied on textile fabric. We found that color intensity performance and photodegradation of the photochromic pigment can be evaluated using a relatively small amount of necessary irradiation cycles and an advanced setup of time/intensity UV radiation exposure. Keywords: Color intensity, Fatigue resistance, Photochromic phenomena, UV irradiance time

Abstract: Mechanical, damping and specific properties of new structural high-damping steel have been studied in the present research. Studied high-damping steel was specially produced by the JSC Severstal in order to obtain metallic material with specified level of damping and mechanical properties. Experiments show that the damping properties of industrial high-damping steel are comparable with damping properties of high-purity damping alloys, produced using laboratory equipment. Mechanical properties of the industrial high-damping steel were found to be comparable with the level of properties of well-known structural steels, widely used in the modern industry. Analysis of the combination of mechanical and specific properties of the new steel indicates that this material can be used for the construction of rigid structures requiring high damping. Specific features of practical application of high-damping steels are also discussed.

Abstract: In this paper the design, experimental and numerical simulation of a test rig for stabilizer bars fatigue resistance study is presented. A virtual CAD of the test rig is developed, for design and simulation purposes. A dynamic simulation model is developed in ADAMS software, to study the stabilizer bar durability. Strain gauge transducers are used to measure the deformations of the stabilizer bar.