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Abstract The design of cylinder liners, pistons, and piston rings is subject to different conflicting goals. In addition to a loss-free seal of the combustion chamber, sufficient oil must be present between the friction partners. Both the reduction of piston assembly friction and the minimization of oil consumption are crucial to achieve the strictly defined CO2 and emission standards. To master this challenge and find the best compromise requires a lot of system-specific know-how. The automobile and engine manufacturers focus mainly on friction-reducing measures, which are analyzed with different measuring methods such as the floating-liner method, the strip-down method, or the instantaneous indicated mean effective pressure (IMEP) method. However, the interpretation of the results and the development of realistic simulation models lacks information about the oil film behavior and the film thickness.

Abstract The impact of Laser Beam Machining (LBM) process parameters on Surface Roughness (SR) and kerf width during machining is investigated in this work. Stainless Steel is a material that is resistant to corrosion. LBM is a nontraditional machining method in which material is removed by melting and vaporizing metal when a laser beam collides with the metal surface. There are numerous process variables that influence the quality of the LBM-cut machined surface. However, the most essential factors are laser power, cutting speed, assist gas pressure, nozzle distance, focus length, pulse frequency, and pulse width. SR, Material Removal Rate (MRR), and kerf width and heat affected zone are significant performance indicators in LBM. The influence of LBM process parameters on SR and kerf width while machining stainless steel material is investigated in this study.

Abstract This article presents an approach for circumferential tire tread profiling using Laser Section (LS) technique and Photometric Stereo (PS) technique. The proposed approach uses a digital camera as the only data acquisition device, and one laser line generator and sixteen 5 mm white LEDs to provide different lighting conditions. LS technique uses the illumination of the laser line generator to measure the depth profile of one cross section of the tire surface, while PS technique utilizes the difference of the appearance of the tire surface under different lighting conditions to recover the geometry information of the tire tread with pixel resolution. The fusion of the two techniques results in a high-resolution three-dimensional (3D) profiling of the tire tread. A system to apply the proposed approach was developed, with the necessary calibration steps explained, with a step motor for circumferential measurement.

Abstract The article is devoted to laser interferometry technology for investigating the strain and stress state (SSS) of heat engine details and units. It is an efficient alternative to traditional technologies based on using strain gauges. It has been shown that the use of traditional technologies to experimentally investigate the SSS of heat engine complex details when using the strain gauges requires a significant amount of research and time. Thus, deploying physical effects previously not used for solving similar problems is a perspective research direction that includes laser interferometry technology. The article deals with its use to experimentally investigate the SSS of complex details, such as a crankcase block of an internal combustion engine (ICE). Laser interferometry research is based on the use of holographic interferometry, speckle photography, electronic speckle pattern interferometry, and modern methods of computer simulation.

Abstract A key problem of the construction of fully electric aircraft is the limited energy density of battery packs. It is generally accepted that this can only be overcome via new, denser battery chemistry together with a further increase in the efficiency of power utilization. One appealing approach for achieving the latter is using laser-assisted filler-based joining technologies, which offers unprecedented flexibility for achieving battery cell connections with the least possible electrical loss. This contribution presents our results on the effect of various experimental and process parameters on the electrical and mechanical properties of the laser-formed bond.

Abstract A novel method of measuring the thickness of deposits on engine pistons, including within ring grooves, is described. A laser profilometer is used in conjunction with a rotary stage to measure a continuous profile of the piston with deposits, and the measurement is repeated after cleaning the deposits from the piston. Algorithms for aligning the scans and determining the differential thickness are described, and results are compared to deposit thickness measurements using a contact-type magnetic induction coating thickness gauge. This method allows continuous measurement of deposit thickness across the entire surface including lands and ring grooves as well as quantification of the volume of the deposits.

Abstract Previous studies have shown that injector aging adversely affects the diesel engine spray formation and combustion. It has also been shown that the oxygenated fuel additive tripropylene glycol monomethyl ether (TPGME) can lower soot emissions. In this study, the effects of injector aging and TPGME on the late-cycle oxidation of soot were investigated using laser diagnostic techniques in a light-duty optical diesel engine at two load conditions. The engine was equipped with a quartz piston with the same complex piston geometry as a production engine. Planar laser-induced incandescence (LII) was used to obtain semiquantitative in-cylinder two-dimensional (2D) soot volume fraction (fv ) distributions using extinction measurements. The soot oxidation rate was estimated from the decay rate of the in-cylinder soot concentration for differently aged injectors and for cases with and without TPGME in the fuel.

Abstract Although tread block deformation analysis is important, the deformation measurement is difficult because fast-rotating tires maintain a continuous contact with the road surface. Furthermore, capturing small displacements near the edge of tread blocks using a high-speed camera is difficult because of the particularly limited resolution. Additionally, the tread blocks being significantly deformed at the edge and susceptible to wear powder, the state change of the feature points, is highly probable. To overcome these problems, a system that obtains high-resolution images and measures the deformation of a fast-rotating body (tire) is proposed herein. The developed system captures the deformation behavior through intermittent imaging. To further measure the strain distribution, fine tracking markers are drawn on the tread block using a laser processing machine. The displacement of the marker is calculated using the particle mask correlation method.