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Abstract The use of appropriate loads and regulations is of great importance in weld fatigue assessment of rail on-track maintenance equipment and similar vehicles for optimized design. The regulations and available loads, however, are often generalized for several categories, which proves to be overly conservative for some specific categories of machines. EN (European Norm) and AAR (Association of American Railroads) regulations play a pivotal role in determining the applicable loads and acceptance criteria within this study. The availability of track-induced fatigue load data for the cumulative damage approach in track maintenance machines is often limited. Consequently, the FEA-based validation of rail track maintenance equipment often resorts to the infinite life approach rather than cumulative damage approach for track-induced travel loads, resulting in overly conservative designs.

Abstract Sustainable practices are taking precedence across many industries, as evident from their shift towards the use of environmentally responsible materials, such as natural fiber-reinforced acrylated epoxidized soybean oil (NF-AESO). However, due to the lower reactivity of AESO, the curing reaction usually requires higher temperatures and longer curing time (e.g., 150°C for 6-12 h), thus making the entire process unsustainable. In this study, we demonstrate the potential power of photons towards manufacturing NF-AESO composites in a sustainable manner at room temperature (RT) within 10 min. Two photoinitiators, i.e., the 2,2-dimethoxy phenylacetophenone (DMPA) and 1-hydroxycyclohexyl phenyl ketone (HCPK), were evaluated and compared with the thermal initiator, i.e., tert-butyl perbenzoate (TBPB). Based on the mechanical performance of the AESOs, the photoinitiation system for NF-AESO was optimized.

Abstract Damage is accumulated by vehicles as they travel. Current damage methods allow for the total accumulated damage to be identified; however, they do not allow for identification of the road segments that induce the largest component of the damage. The objective of this article is to develop a measure, Localized Pseudo Damage (LPD), which defines the amount of damage each individual road excitation contributes to the total accumulated pseudo damage. A novel theoretical development of LPD along with analytical and discrete simulation analyses is presented. The results show that the LPD is causal and correctly identifies the location and magnitude of damaging events. This is further demonstrated with the application of the method on a real road surface.

Abstract To protect ship equipment of river and sea transport, it is suggested to use polymeric protective coatings based on epoxy diane oligomer ED-20, polyethylene polyamine (PEPA) curing agent and filler, which is a departure from industrial production. Thus the purpose of the work is analysis of major dependency of the properties on the content of fillers that allowed to revealed the critical filler content (furnace black) in composites to form a protective coating with the required set of characteristics. The infrared (IR) spectral analysis was used to investigate the presence of bonds on the surface of particles of the PM-75 furnace black, which allows us to assess the degree of cross-linking of the polymer. The influence of the content of dispersed furnace black on the physicomechanical and thermophysical properties and the structure of the protective coating is investigated.

Abstract Equal-channel angular pressing (ECAP) is among the most applicable severe plastic deformation processes used to fabricate ultrafine-grained materials with superior mechanical properties. In this work, a commercial purity aluminum has been processed via ECAP process up to four passes. The influence of ECAP routes (A and Bc) on the mechanical properties of the material and its grain size was investigated. Microstructural observations of the as-annealed and the rods processed via ECAP were undertaken using optical microscopy. Hardness profiles and contour maps of sections cut perpendicularly and parallel to the load direction were assessed to investigate the effect of ECAP processing on the hardness distribution across the deformed rods. Compressive properties of the rods were also examined. In addition, digital images correlation was used to display the stress distribution along the longitudinal section of the processed sample during the compression test.

Abstract The causes of failure due to cracking in the resistance spot welding of the advanced high-strength steels dual-phase 590 (DP590) were investigated using scanning electron microscopy (SEM), optical microscopy, and the tensile-shear test. The results showed that by increasing the current amount, the formation of the melting zone occurred in the heat-affected zone, leading to the cracking in this area, reducing the tensile strength and decreasing the mechanical properties; the initiation and growth of cracking and failure in this region also happened. In the heat-affected zone, by increasing the current amount with the softening phenomenon, the recrystallized coarse grains also occurred, eventually resulting in the loss of mechanical properties. The results of the tensile-shear test also indicated that by increasing the current up to 12 kA, the strength was raised, but the ductility was reduced.

Abstract Heavy commercial vehicles play an important role in creating the trade and economic balance of countries. Also, the durability and safety of heavy commercial vehicles come to the fore. Heavy commercial vehicles consist of two parts. These are the chassis area with the equipment that allows the vehicle to move and the cabin section where the driver is located. The cabin area is the most important area that ensures the highest level of driver safety. Considering that the production of trucks is increasing day by day, it is inevitable for companies to increase their R&D activities in the field of cabin and cabin suspension systems for much safer, durable, and comfortable trucks. This study aims to determine the safe torque value of the fasteners and their assembly sequence of the Cab Suspension Console, which is one of the most important connection parts in a truck and which can cause a fatal accident by breaking.

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Abstract In the present study, the mechanical performances of plain carbon steel were explored based on the grain growth behavior. In the first step, the samples were normalized at different temperatures ranging from 900°C to 1100°C for 30, 60, 100, 150, and 200 min, respectively. In order to measure the grain size, the planimetric technique of Jeffries was used based on the optical micrographs taken for each sample. The mechanical properties of each grain such as hardness, elongation, yield, and tensile strength were studied, depending on the conventional methods. Experimental results showed that the increase in both heating temperature and holding time enhances grain growth, while the growth rate decreases with increasing time. The initial grain size and proportionality constant were calculated at 950°C, where K = 2.26 μm2/min and D 0 = 25.09 μm. Moreover, a significant increase in strength and hardness was observed with a decrease in grain size.

Abstract In this article, Al-Mg-Si-Mn alloy (AA6082) is butt joined by employing friction stir welding (FSW). The mechanical and metallurgical properties of joints are analyzed by conducting tensile and microhardness testing, respectively. To measure the temperature at different locations, eight thermocouples (L-shaped k-type) are placed at equal distance from the centerline. Least square method attempts to calculate the temperature at the centerline of joints. The process parameters are also optimized using Taguchi’s five-level experimental design. The optimum process parameters are determined, employing ultimate tensile strength (UTS) as a response parameter. A statistical test “analysis of variance” is used to check the adequacy of the model. It has been observed that rotational speed and feed rate are the predominant factors for UTS and microhardness.

Abstract Stress-based sheet metal fatigue near nuts welded to thin sheets is one of the necessary design processes for car bodies. In this investigation, the influence of the attachment contact on the localized fatigue mechanism is examined through finite element (FE) models and controlled fatigue experiments. First, a fatigue experimental setup, which includes a thin-sheet closed-hat section with a weld nut bolted to a thick attachment piece, is designed to minimize the uncertainty of the influence of the fixtures on the experimental results. The experiments are carried out on 0.9- and 1.0-mm thick hat sections with a square weld nut under force control conditions with complete reversed loading. Due to the contact, the test specimen performs as a bilinear spring that has a lower stiffness in the upstroke direction when compared to the downstroke direction where full contact of the attachment occurs with the hat section.

Abstract This study focused on the synthesis and characterization of monodisperse spherical TiO2 nanoparticles doped on the surface with Se (IV) in order to increase the mechanical properties of the bonded joint reinforcing. Work will begin with the synthesis of monodisperse quasi-spherical TiO2 nanoparticles with a modal diameter of less than 20 nm, using the sol-gel technique. Se (IV) selenium surface doping changed the specimen’s chemistry and physics. Different initial concentrations of the doping element will be tested. Next, a physicochemical characterization of the different solid systems will be carried out in order to determine the effect of the doping element on the properties of titanium dioxide. Their morphology and size will be studied through transmission electron microscope observations; volume chemical composition by X-ray diffraction analysis, EDX (energy-dispersive X-ray), and XRF (X-ray fluorescence).

Abstract Due to the limitations of current battery manufacturing processes, integration technology, and operating conditions, the large-scale application of lithium-ion batteries in the fields of energy storage and electric vehicles has led to an increasing number of fire accidents. When a lithium-ion battery undergoes thermal runaway, it undergoes complex and violent reactions, which can lead to combustion and explosion, accompanied by the production of a large amount of flammable and toxic gases. These flammable gases continue to undergo chemical reactions at high temperatures, producing complex secondary combustion products. This article systematically summarizes the gas generation characteristics of different types and states of batteries under different thermal runaway triggering conditions. And based on this, proposes the key research directions for the gas generation characteristics of lithium-ion batteries.

Abstract Sound ductile iron (DI) welded joints were performed using developed coated electrode and optimized welding parameters including post weld heat treatment (PWHT).Weldments consisting of weld metal, partially melted zone (PMZ), heat affected zone (HAZ) and base metal were austenitized at 900 °C for 2 hour and austempered at 300 °C and 350 °C for three different holding time (1.5 hour, 2 hour and 2.5 hour). In as-weld condition, microstructures of weld metal and PMZ show ledeburitic carbide and alloyed pearlite, but differ with their amount. Whereas microstructure of HAZ shows pearlite with some ledeburitic carbide and base metal shows only ferrite.

Abstract In this work, the complex relationship between deformation history and residual stresses in a magnesium-to-aluminum self-pierce riveted (SPR) joint is elucidated using numerical and experimental approaches. Non-linear finite element (FE) simulations incorporating strain rate and temperature effects were performed to model the deformation in the SPR process. In order to accurately capture the deformation, a stress triaxiality-based damage material model was employed to capture the sheet piercing from the rivet. Strong visual comparison between the physical cross-section of the SPR joint and the simulation was achieved. To aid in understanding of the role of deformation in the riveting process and to validate the modeling approach, several experimental measurements were conducted. To quantify the plastic deformation from the piercing of the rivet, micro hardness mapping was performed on a cross-section of the SPR joint.

Abstract In this study, active-passive filling friction stir repairing (A-PFFSR) process was employed to repair the volume defects in friction stir welding (FSW) joints of Al-Cu alloy. The volume defects with varied geometries were first machined into taper holes, which are similar to keyhole defect by a rotational tool with a threaded pin. Then, the keyhole defect was effectively filled with the materials around the keyhole and an additional filler using a number of nonconsumable pinless tools with the shoulders having six spiral flutes. The macro/microstructures, microhardness, and tensile properties of the repaired joints were investigated. The influences of plunge speed on macro/microstructures and mechanical properties of the repaired joints have been analyzed too. It was noticed that decreasing plunge speed was effective to improve the frictional heat and material flow, which increased joint surface integrity avoiding interfacial drawbacks.

Abstract The Friction stir welding (FSW) is recently presented so to join different materials without the melting process as a solid-state joining technique. A widely application for the FSW process is recently developed in automotive industries. To create the welded components by using the FSW, the plunged probe and shoulder as welding tools are used. The Finite Element Method (FEM) can be used so to simulate and analyze material flow during the FSW process. As a result, thermal and mechanical stresses on the workpiece and welding tool can be analyzed and decreased. Effects of the welding process parameters such as tool rotational speed, welding speed, tool tilt angle, depth of the welding tool, and tool shoulder diameter can be analyzed and optimized so to increase the efficiency of the production process. Material characteristics of welded parts such as hardness or grain size can be analyzed so to increase the quality of part production.

Abstract The present work deals with the damage life correlation of vehicle-level testing results of an axle housing for different road load conditions with the accelerated bench testing experiment results to reduce product development time. Also failure analysis is carried out to overcome the mechanical strength losses caused by the hot forming process during the manufacturing of housings. Commercial vehicle torture test tracks are built to reflect the forces similar to vehicle usage conditions from lighter to severe loadings. Strain data and calibrated force values are captured at the critical loading points in the axle for one cycle, at actual vehicle-driven speeds, to reflect the accelerated load values on five different track conditions. Damages estimation carried out based on the road loads reflects there will be no failure of axle housings till the acceptance of 120 repeats in different track combinations.

Abstract The aluminum alloy 7075 sheets have drawn more attention in recent years in the automotive industry for lightweighting. Hot stamping of high-strength aluminum alloy has been developed to improve the formability of the part without springback. Obtaining an adequate quench rate is a critical step of the hot stamping process and corresponds to good strength and corrosion resistance. This work looks at measuring the quench rate of 7075 at advanced aging (AA) and T6 condition via two different approaches: forced air and water with various temperatures. The results verify that water is a superior form of quenching, i.e., from 50°C/s to 550°C/s, the forced air-cooled quench rate is 2°C/s-10°C/s. Besides, mechanical properties such as yield strength, ultimate tensile strength, and uniform elongation were measured by tensile testing. As a result, a correlation between the quench rate and final mechanical properties was developed.