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Abstract With the introduction of advanced lightweight materials with complex microstructures and behaviors, more focus is put on the accurate determination of their forming limits, and that can only be possible through experiments as the conventional theoretical models for the forming limit curve (FLC) prediction fail to perform. Despite that, CAE engineers, designers, and toolmakers still rely heavily on theoretical models due to the steep costs associated with formability testing, including mechanical setup, a large number of tests, and the cost of a stereo digital image correlation (DIC) system. The international standard ISO 12004-2:2021 recommends using a stereo DIC system for formability testing since two-dimensional (2D) DIC systems are considered incapable of producing reliable strains due to errors associated with out-of-plane motion and deformation.

Abstract Three-dimensional patterns representing crosshatched plateau-honed cylinder bores based on two-dimensional Fast Fourier Transform (FFT) of measured surfaces were generated and used to calculate pressure flow, shear-driven flow, and shear stress factors. Later, the flow and shear stress factors obtained by numerical simulations for various surface patterns were used to calculate lubricant film thickness and friction force between piston ring and cylinder bore contact in typical diesel engine conditions using a mixed lubrication model. The effects of various crosshatch honing angles, such as 30°, 45°, and 60°, and texture heights on engine friction losses, wear, and oil consumption were discussed in detail. It is observed from numerical results that lower lubricant film thickness values are generated with higher honing angles, particularly in mixed lubrication regime where lubricant film thickness is close to the roughness level, mainly due to lower resistance to pressure flow.

Abstract Electromagnetic forming (EMF) is a high-speed impulse forming process developed during the 1950s and 1960s to acquire shapes from sheet metal that could not be obtained using conventional forming techniques. In order to attain required deformation, EMF process applies high Lorentz force for a very short duration of time. Due to the ability to form aluminum and other low-formability materials, the use of EMF of sheet metal for automobile parts has been rising in recent years. This review gives an inclusive survey of historical progress in EMF of continuum sheet metals. Also, the EMF is reviewed based on analytical approach, finite element method (FEM) simulation-based approach and experimental approach, on formability of the metals.

Abstract To improve the lubrication and friction of the crankpin bearing (CB) in the engine, the design of surface textures on the bearing surface is proposed and researched based on the CB hydrodynamic dynamic model. To enhance the reliability of the research results and its closeness to reality, the optimal CB parameters, the experimental data of the external dynamic load W0 acting on the crankpin, and the CB surface roughness in the well-known existing researches are referred to as input data for the simulation process. The effect of the distribution density {n, m}, diameter D, and depth of the microcircular textures hd on improving the lubrication and friction are then analyzed based on the indexes of the increase in the oil film pressure, decrease in the solid asperity contacts in the mixed lubrication region (MLR), friction force, and coefficient of friction (COF) between the crankpin and bearing surfaces, respectively.

Abstract New analytical structural stress solutions for a rigid inclusion in a finite square thin plate with clamping edges under opening loading conditions are developed. The new solutions are used to derive new analytical structural stress and stress intensity factor solutions for similar and dissimilar spot welds in cross-tension specimens. Three-dimensional finite element analyses are conducted to obtain the stress intensity factor solutions for similar spot welds and dissimilar magnesium/steel spot welds in cross-tension specimens of equal thickness with different ratios of half-specimen width-to-weld radius. A comparison of the analytical and computational solutions indicates that the analytical stress intensity factor solutions for similar spot welds in cross-tension specimens of equal thickness are accurate for large ratios of half-specimen width-to-weld radius.

Abstract In automotive, the use of heavy structure leads to high consumptions of fuel and resulting high exhaust (CO2) emissions. To curb this problem, nowadays, the conventional steel used for years in automotive structures is currently replaced with other different lightweight materials such as aluminum, magnesium, glass fiber-reinforced polymer, carbon fiber-reinforced polymer, titanium, and so on. On the other hand, compared to the known steel properties and performances, these lightweight materials offer challenging issues related to life cycle, recycling, cost, and manufacturing. But, more than sometimes, reaching the same levels of performances with materials different from steel presents huge difficulties. This represents the cause of researching strategies and techniques to optimize the material distribution and the performances of a component, saving material and consequently reducing weight.

Abstract The greatest frictional contributor in an internal combustion engine is the contact between the piston ring pack and cylinder liner. Therefore, an improved lubrication regime has the potential to raise engine efficiency while lowering emissions, aiding to meet environmental regulations. Previous ultrasonic measurements of the oil film thickness (OFT) between piston rings and the cylinder liner in a marine engine have been subject to several unexpected trends. This article refines the measurement to identify and remove these factors, the trends were found to have arisen due to the detection of ultrasonic reflections from the piston ring outside of the expected alignment zone. The extent of these undesired reflections is thought to be due to the liner thickness providing a relatively large distance for spreading of the ultrasonic wavefront.

Abstract Single point incremental forming (SPIF) is a robust and new technique. In the recent research scenario, materials properties such as microstructure, micro-texture analysis, and crystal structure can be accessed through characterization non-destructive techniques, e.g., scanning electron microscope (SEM), electron backscattered diffraction (EBSD), and X-ray diffraction (XRD). XRD is a non-destructive method for analyzing the fine structure of materials. This study explores how process variables such as wall angle, step size, feed rate, and forming speed affect the parts of large-, medium-, and small-sized truncated cones of aluminum alloy AA3003-O sheet. Several cone parts of truncated cones are used in this investigation to implement Scherrer’s method. The two primary determining factors peak height and crystallite size are assessed for additional analysis in the present research.

Abstract The lubricating properties of diesel are an imperative aspect for the optimal functioning of fuel injection components. Regulatory standards followed by refineries utilize accelerated wear testing methodologies. These tests provide indicative results for judging the lubricity but are not conclusive for determining wear in functional applications attributed to higher loads and other environmental factors. In the course of this article, a tribological evaluation was carried out on Low-Sulfur Diesel (LSD) and Ultralow Sulfur Diesel (ULSD) by utilizing modified test parameters incorporating higher loads and a more extensive gradient of temperature on High-Frequency Reciprocating Rig (HFRR) tribotester. The variance in the resultant coefficient of friction (COF) and wear scar concerning the change in parameters was observed as well as a comparative analysis was drawn between both test fuels.

Abstract The paper presents a complete description of the design and manufacturing of a Carbon Fiber/epoxy mold with an embedded Carbon Fiber resistor heater, and the mold performances in terms of its surface temperature distribution and thermal deformations resulting from the heating. The mold was designed for manufacturing aileron skins from Vacuum Bag Only prepreg cured at 135°C. The glass transition temperature of the used resin-hardener system was about 175°C. To ensure homogenous temperature of the mold working surface in the course of curing, the Carbon Fiber heater was embedded in a layer of a highly heat-conductive cristobalite/epoxy composite, forming the core of the mold shell. Because the cristobalite/epoxy composite displayed much higher thermal expansion than CF/epoxy did, thermal stresses could arise due to this discrepancy in the course of heating.

Abstract The purpose of this article is to study the antifriction and anti-wear effect of GCr15 bearing steel under paraffin base oil and the base oil with two additives of T405 sulfurized olefin and nano-MoS2 and compare the synergistic lubrication effect of two different additives (MoS2 and T405) in paraffin base oil. The tribological properties of GCr15 bearing steel under different lubrication conditions were tested on a ball-on-disk tribometer. The three-dimensional profile of disk’s worn surfaces and the scanning electron microscope (SEM) micrographs of corresponding steel balls were analyzed at the same time. The wettability of lubricating oils on the surface of friction pairs and the dispersibility of MoS2 in base oil were characterized.

Abstract Reducing a vehicle’s weight is an efficient method to reduce energy consumption. Aluminum alloy is the best material for lightweight automobiles. However, the poor formability of aluminum means that it is difficult to develop stamping dies. This study designs a suitable forming tool for aluminum fenders. A simulation and an experiment are used to analyze the formability of aluminum fenders. A theoretical calculation, experimental testing, and sampling comparison are used to verify the design. The material properties of steel and aluminum are firstly studied and compared. The results show that a traditional S-type blank die face design is not suitable for aluminum because of its low tensile strength and the potential for elongation. A relatively flat trapezoid blank die face design is proposed to smooth the variation. However, a flat die face for a trapezoidal blank limits stretching, so another design is essential to improve the formability.

Abstract With increased consumer demand for fuel efficient vehicles as well as more stringent greenhouse gas regulations and/or Corporate Average Fuel Economy (CAFE) standards from governments around the globe, the automotive industry, including the OEM (Original Equipment Manufacturers) and suppliers, is working diligently to innovate in all areas of vehicle design. In addition to improving aerodynamics, enhancing internal combustion engines and transmission technologies, and developing alternative fuel vehicles, mass reduction has been identified as an important strategy in future vehicle development. In this article, the development, analysis, and experiment of multi-cornered structures are presented. To achieve mass reduction, two non-traditional multi-cornered structures, with twelve- and sixteen-cornered cross-sections, were developed separately by using computer simulations.

Abstract Powder metallurgy is a widely used manufacturing methodology in the gearbox industry. Noise and vibration is a common cause for concern in the gearbox industry due to the continuous contact between gear teeth at high rotational frequencies. Despite this, limited research has been performed investigating the modal properties of powder metal products. This work investigates the damping ratios of a copper-infiltrated steel powder metal ring and a hot-rolled steel ring both experimentally and computationally. Negligible difference was observed between the damping ratios of the powder metal and hot-rolled steel rings. Two proportional damping models were investigated to predict the damping ratios of the powder metal ring. It was found that the Caughey damping model was the most accurate, generating damping ratios within 2.36% for a frequency bandwidth of up to 4000 Hz.

Abstract Research and development efforts in the automotive industry have been long focused on crashworthy, durable vehicles with the lowest mass possible as higher mass requires more energy and, thus, causes more CO2 emissions. One way of approaching these objectives is to reduce the total vehicle weight by using higher strength-to-weight ratio materials, such as Advanced High-Strength Steels (AHSS). Typically, as the steel gets stronger, its formability is reduced. The steel industry has been long developing (so-called) third-generation (Gen3) AHSS for the automotive industry. These grades offer higher formability compared to first-generation (Gen1) and cost less compared to the second-generation (Gen2) AHSS. Transformation Induced Plasticity (TRIP)-aided Bainitic Ferrite (TBF) and Quenching and Partitioning (Q&P) steel families are considered to be the Gen3 AHSS.

Abstract Cast magnesium (Mg) door inner panels can provide a good combination of weight, functional, manufacturing, and economical requirements. However, several challenges exist including casting technology for thin-wall part design, multi-material incompatibility, and relatively low strength versus steel. A project was supported by the US Department of Energy to design and develop a lightweight frame-under-glass door having a thin-wall, full die-cast, Mg inner panel. This development project is the first of its kind within North America. The 2.0 mm Mg design, through casting process enablers, has met or exceeded all stiffness and side-impact requirements, with significant mass reduction and part consolidation. In addition, a corrosion mitigation strategy has been established using industry-accepted galvanic isolation methods and coating technologies. The performance of the Mg design has been demonstrated through component and vehicle tests.

Abstract The purpose of this study is to examine the phenomenon of Dynamic Particle Generation in lubricating greases that are used in a variety of critical Aerospace mechanisms. Particle Generation occurs in bearings, ball screws, and other mechanical devices where dynamic conditions are present. This should not be confused with outgassing as particle generation is unrelated to the pressure effects on a system. This is a critical factor in many systems as particle generation can contaminate systems or processes causing them to fail. These failures can lead to excessive costs, production failure, and equipment damage. In this study, several greases made from Multiplyalkylated Cyclopentane and Perfluoropolyether base fluids were tested to evaluate their particle generation properties. This particle generation phenomenon was studied using a custom test rig utilizing a high precision cleanroom ball-screw to simulate true application conditions.

Abstract With the trends to increase drain oil interval to reduce the cost of ownership of Heavy-Duty vehicles and to use low ash oils to mitigate degradation of Diesel Particulate Filter performance, the efficiency of lubricant additive s, especially the antiwear ones, are of great interest. However, most of the tribological tests are still done with fresh oils or, in a few cases, with artificially aged oils. In this work, the piston ring and cylinder liner were rig tested for friction and wear on a short reciprocating tester with two oils: a fully formulated SAE 10W-40 API CI-4/ACEA E7 and a sample of the same oil after 500 h of an engine test. Friction was measured along with the rig test, and liner wear was evaluated after test by different parameters based on the bearing curve of roughness. Compared with the fresh oil, the aged oil showed slightly lower friction, but significantly higher liner wear.

Abstract Reducing the friction of the internal combustion engine (ICE) is of major interest to reduce fuel consumption and greenhouse gas (GHG) emissions. A huge potential for friction reduction is seen in the piston ring-cylinder liner (PRCL) coupling. Approaching the cylindrical liner shape in the hot operation state will enhance the PRCL conformation. Recently, newly developed freeform honing techniques can help to achieve this perfect cylinder shape. This article presents a numerical study of the effect of freeform honing on the geometrical performance of the liner in the hot operation state. The freeform honed liner (TR) concept is based on the approach of reversing the local deformation of a conventional circular liner. A validated computational model for a gasoline engine is used to compare the geometrical performance of those TR cases with circular, elliptical (EL), and conical elliptical liners (NEL) at different operational points.

Abstract Automotive-grade high-strength steels are galvanized for improved corrosion resistance. However, selective oxidation of alloying elements during annealing heat-treatment may influence the subsequent zinc (Zn) coating quality. The formation of internal and external oxides depends on the alloy composition, especially the Si/Mn ratio, and the oxygen potential of the annealing atmosphere. In this work, a dual-phase (DP) steel was intercritically annealed with varied fuel-to-air ratios in a direct-fired furnace and then galvanized in a Zn bath with 0.2 wt% Al. The type of internal and external oxides and the interfacial structures between the steel substrate, the Al-Fe-Zn inhibition layer, and the Zn coating were examined by using site-specific focused ion beam (FIB) and transmission electron microscopy (TEM).