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This work aims to investigate and assess the beneficial function and feasibility of nanofluids in minimum quantity lubrication (MQL) assisted machining. The goal is to develop newly generated CNT based nano hybrid cutting fluid and demonstrate its effect on surface roughness of Al alloy. Moreover, the fabricated nano hybrid cutting fluid will eventually reduce cutting fluid consumptions and maintain an eco-friendly environment. Three conditions were used to perform the machining process such as dry condition, conventional oil and Al_2O_3/CNT nanoparticle with EVO oil as base fluid. The lowest surface roughness achieved for nanofluid and the maximum surface roughness for the dry condition. In terms of looking for optimum parametric combination, Artificial Neural Network (ANN) and Response Surface Methodology (RSM) have been used. The ANN technique has proved its efficiency since its correlation coefficients, mean prediction errors (MPEs), and root mean square errors (RMSEs) are small compared to the RSM approach.

The objective of the presented work is to improve the machining parameters of fibre reinforced polymer (FRP) using Taguchi's robust design technique. A large number of variables impact the quality of the completed component throughout the machining process. The quality of machined FRP components is greatly influenced by the surface roughness. Manufacturers can make sure that the finished product fulfils the necessary quality requirements and is cost-effective by optimizing machining settings to achieve the specified surface roughness. Optimizing machining parameters for achieving the desired surface roughness can help reduce production costs by minimizing waste, improving tool life, and reducing the need for post-processing operations. To optimize the process, Three levels of each parameter were chosen for investigation for each such adjustable process parameter. Machining was performed on a CNC milling machine using a carbide end mill. Experiments were conducted utilising Taguchi's technique to generate an experiment design (L9 orthogonal array). Analysis of variance was used to determine the impact of each parameter (ANOVA). The recommended control factor values for the best possible surface finish of FRP are 1.64 m, 400 rpm spindle/cutting velocity, 1.5 mm depth of cut and 0.3 millimetre/revolution feed rate. Surface roughness was shown to be most impacted by cutting speed, followed by feed rate and depth of cut. To determine the relationship between process parameters and quality attributes, regression analysis and response surface methodology was used.

In this investigation on Viscoelastic magnetic abrasive finishing process, a deep learning model is applied to predict the change in surface roughness. A dedicated experimental setup along with the abrasive media was prepared to carry out the finishing process. Experiments were performed on mild steel to inspect the effect of several parameters such as finishing time, magnetic flux density, abrasive mesh number, magnetic tool rotational speed, feed, ultrasonic amplitude on the surface roughness. The paper aims to provide a cost-effective as well as time-effective predictive method to depict the change in surface roughness.

Aluminum is used widely for components of renewable energy, such as wind and hydro turbines. Some of these components require a milling process to improve surface quality. This research presented the influence of lubrication on vibration and surface roughness in the milling process. The first step, the modal parameters data were obtained by the impulse response method using a hammering test with an impulse hammer, then the milling tests experiment were conducted in three different cutting conditions i.e. dry cutting, wet cutting with coolant and oil. The three-axis accelerometer was used to collect acceleration signals of milling test. The collected acceleration signals then were analyzed using Fast Fourier Transform (FFT) to first transform the signals into frequency domain and after that more phenomenon of the milling process in frequency domain were analyzed. Then, the surface roughness was measured using a surface roughness tester. The results showed that the amplitude of signal is lower in milling with lubricant than dry cutting. The cutting condition was stable in wet cutting for both types of lubricant while the chatter occurs in dry cutting. Then, the surface roughness for wet cutting is better than dry cutting and the best of roughness is wet cutting with lubricant of coolant in this experiment.

Fatigue properties of parts are of particular concern for safety-critical structures. It is well-known that discontinuities in shape or non-uniformities in materials are frequently a potential nucleus of fatigue failure. This is especially crucial for the Ti6Al4V alloy, which presents high susceptibility to the notch effect. This study investigates how post-processing treatments affect the mechanical performance of Ti6Al4V samples manufactured by laser powder bed fusion technology. All the fatigue samples were subjected to a HIP cycle and post-processed by machining and using combinations of alternative mechanical and electrochemical surface treatments. The relationship between surface properties such as roughness, topography and residual stresses with fatigue performance was assessed. Compressive residual stresses were introduced in all surface-treated samples, and after tribofinishing, roughness was reduced to 0.31 ± 0.10 µm, which was found to be the most critical factor. Fractures occurred on the surface as HIP removed critical internal defects. The irregularities found in the form of cavities or pits were stress concentrators that initiated cracks. It was concluded that machined surfaces presented a fatigue behavior comparable to wrought material, offering a fatigue limit superior to 450 MPa. Additionally, alternative surface treatments showed a fatigue behavior equivalent to the casting material.

From microplastics resuspending into the atmosphere to earth particles left behind during extraterrestrial explorations, the resuspension of microparticles by a turbulent gas flow occurs in many natural and industrial systems. Wall surfaces, onto which particles initially adhere, are rarely smooth and this surface roughness affects their resuspension. Available experimental data on particle resuspension have been obtained with substrates, whose surfaces are either unaltered or manually abraded with, for instance, sand blasting. In these experiments, the roughness elements span a wide size range and are in-homogeneously distributed in space. Surface functionalization is a modern technique allowing the precise fabrication of a wall surface with well-characterized microstructures, hence reducing the asperity randomness associated with conventional abrasion techniques. Taking advantage of surface functionalization, we present here a new set of reference data, where the wall asperities are represented by a structured arrangement of micropillars and microcubes. Adhesion force measurements and particle remaining fraction against gas velocity, at Reynolds number up to 8000, are reported for one reference and two artificially roughened substrates. Laboratory measurements show that the microasperities have little to moderate effect on the mean adhesion force and the threshold velocity, at which half of the 100-µm particles resuspend. The standard deviations are, however, significantly affected. The presented results will primary contribute to the improvement of resuspension models, which until now rely on a simplified representation of the surface roughness elements. The presented measurements are highly compatible with such models, which involve elementary roughness features, such as hemispherical asperities superimposed with a flat plate.

In the past few years, FDM basedpolymer 3D printing process has flourished mainly with ABS filaments as a thermoplastic source. Food packing, medical, marine and agriculture industries employdevices and other usable items made of polymers. Utilizing layered fabrication components in these areascompelthem to have self-cleansing, anti-freezing and corrosion resistant surfaces. It is generally complex and expensive to prepare hydrophobic coatings.The present work is related to the development of a surface coating on 3D printed ABS specimens with the mentioned properties. 3D printed specimens were fabricated using Flash Forge 3D printer without any modifications, and the hydrophobic coatings were achieved by dip coating process using Tricalcium phosphate-chitin solutions with a ratio of 70:30. Static contact angle measurement was employedin gaging wettability impact on dip coated 3D printed specimens. By using digital vernier calipers and profilometer (SJ410), dimensional accuracy and surface roughness were assessed pre and post-coating. According to ASTM D570-98, water absorption tests were conducted at different time intervals. Results of the experiment showed that the hydrophobic solutions had been successfully synthesized. The maximum contact angle was achieved for solution 1(4g of tricalcium phosphate solution with 0.3g chitin solution) i.e., 109.3°. Improvement in the textureof 3D printed ABS surfaceswas observed after dip coating. Dip-coated 3D printed ABS specimens exhibited minimal absorption based on their weight gain per area.

We present an optical sensing methodology to estimate the fatigue damage stateof structures made of carbon fiber reinforced polymer (CFRP), by measuring variations on the surface roughness. Variable amplitude loads (VAL), which represent realistic loads during aeronautical missions of fighter aircraft (FALSTAFF) have been applied to coupons until failure. Stiffness degradation and surface roughness variations have been measured during the life of the coupons obtaining a Pearson correlation of 0.75 between both variables. The data were compared with a previous study for Constant Amplitude Load (CAL) obtaining similar results. Conclusions suggest that the surface roughness measured in strategic zones is a useful technique for structural health monitoring of CFRP structures, and that it is independent of the type of load applied. Surface roughness can be measured in the field by optical techniques such as speckle, confocal perfilometers and interferometry, among others., Sección Deptal. de Óptica (Óptica), Fac. de Óptica y Optometría, TRUE, pub

The dataset presented contains microtopographies of various materials and processing methods. These microtopographies were measured using a Confocal Laser Scanning Microscope, which provides RGB-D data. This means the dataset comprises accurate height maps for each measurement and microscopic RGB images. The height maps can be used to quantify and characterize small-scale surface features such as pits and grooves, surface roughness, texture direction, and surface anisotropy. These features can significantly impact a material's properties and behavior, making them essential in many fields, such as biomaterials and tribology. Additionally, the dataset contains metadata about the specimens and the measurement conditions, such as material, surface processing method, roughness, and optical magnification. Therefore, this dataset provides an opportunity to develop and test surface classification and characterization algorithms.

In this investigation on Viscoelastic magnetic abrasive finishing process, a deep learning model is applied to predict the change in surface roughness. A dedicated experimental setup along with the abrasive media was prepared to carry out the finishing process. Experiments were performed on mild steel to inspect the effect of several parameters such as finishing time, magnetic flux density, abrasive mesh number, magnetic tool rotational speed, feed, ultrasonic amplitude on the surface roughness. The paper aims to provide a cost-effective as well as time-effective predictive method to depict the change in surface roughness.

The objective of the presented work is to improve the machining parameters of fibre reinforced polymer (FRP) using Taguchi's robust design technique. A large number of variables impact the quality of the completed component throughout the machining process. The quality of machined FRP components is greatly influenced by the surface roughness. Manufacturers can make sure that the finished product fulfils the necessary quality requirements and is cost-effective by optimizing machining settings to achieve the specified surface roughness. Optimizing machining parameters for achieving the desired surface roughness can help reduce production costs by minimizing waste, improving tool life, and reducing the need for post-processing operations. To optimize the process, Three levels of each parameter were chosen for investigation for each such adjustable process parameter. Machining was performed on a CNC milling machine using a carbide end mill. Experiments were conducted utilising Taguchi's technique to generate an experiment design (L9 orthogonal array). Analysis of variance was used to determine the impact of each parameter (ANOVA). The recommended control factor values for the best possible surface finish of FRP are 1.64 m, 400 rpm spindle/cutting velocity, 1.5 mm depth of cut and 0.3 millimetre/revolution feed rate. Surface roughness was shown to be most impacted by cutting speed, followed by feed rate and depth of cut. To determine the relationship between process parameters and quality attributes, regression analysis and response surface methodology was used.

The aim of this study was to evaluate the whitening and abrasion effects of dentifrices containing different whitening agents on artificially stained and unstained enamel. 160 human dental enamel discs were distributed into four groups according to the type of dentifrices applied on them (n=40): Group I, non-whitening dentifrice (control group); Group II, dentifrice containing charcoal; Group III, dentifrice containing blue covarine; Group IV, dentifrice containing hydrogen peroxide. Half of the specimens in each group were immersed in coffee solution. Color measurements were evaluated from stained and unstained specimens before and after brushing by a spectrophotometer. The surface roughness of each unstained specimen was analyzed using a profilometer after the brushing and bleaching. The surface of one randomly selected specimen from each group was observed using a scanning electron microscope (SEM). Statistical analysis of the color change was performed using the Kruskal-Wallis test. The one-way ANOVA was used to evaluate surface roughness. Group III provided significantly higher recovery on ∆E00 values than other groups on the unstained enamel (p<0.05). Group IV showed significantly the highest ∆E00 values on stained enamel (p<0.05) and also Group IV showed the highest surface roughness values (p<0.05), SEM revealed a more irregular surface in groups III and IV. It can be stated that dentifrice containing blue covarine is both an effective and a safe way to provide whiter teeth with routine home tooth brushing., El objetivo de este estudio fue evaluar los efectos de blanqueamiento y abrasión de los dentífricos que contienen diferentes agentes blanqueadores en el esmalte teñido y no teñido artificialmente. Se distribuyeron 160 discos de esmalte dental humano en cuatro grupos según el tipo de dentífrico aplicado sobre ellos (n=40): Grupo I, dentífrico no blanqueador (grupo control); Grupo II, dentífrico que contiene carbón vegetal; Grupo III, dentífrico que contiene azul; Grupo IV, dentífrico que contiene peróxido de hidrógeno. La mitad de los especímenes de cada grupo se sumergieron en una solución de café. Las mediciones de color se evaluaron a partir de especímenes teñidos y no teñidos antes y después del cepillado con un espectrofotómetro. La rugosidad de la superficie de cada muestra sin teñir se analizó utilizando un perfilómetro después del cepillado y del clareamiento. La superficie de un espécimen seleccionado al azar de cada grupo se observó utilizando un microscopio electrónico de barrido (MEB). El análisis estadístico del cambio de color se realizó utilizando la prueba de Kruskal-Wallis. Se utilizó el ANOVA para evaluar la rugosidad de la superficie. El grupo III proporcionó una recuperación significativamente mayor en los valores de ∆E00 que otros grupos en el esmalte no teñido (p<0,05). El Grupo IV mostró significativamente los valores más altos de ∆E00 en el esmalte teñido (p<0.05) y también el Grupo IV mostró los valores más altos de rugosidad superficial (p<0.05), el análisis en MEB reveló una superficie más irregular en los grupos III y IV. Se puede afirmar que el dentífrico que contiene azul es una forma efectiva y segura de proporcionar dientes más claros con el cepillado de rutina en el hogar.

The curing characteristics of photopolymer resin determine the relationship between the vat polymerization (VP) process parameters and the layer thickness, geometric accuracy, and surface quality of the 3D printed specimen. Dispersing filler material into the photopolymer resin changes its curing characteristics because the filler scatters and absorbs light, which modifies the curing reaction. However, the ability to cure photopolymer resin with high filler volume fraction is important to 3D print material specimens for specific engineering applications, e.g. structural polymer composite materials, electrical and thermal conductive materials, and ceramic materials for biological and high-temperature environments. We methodically measure the curing characteristics of diacrylate/epoxy photopolymer resin with dispersed glass microspheres. The experiments show that the curing depth, degree-of-cure, and surface roughness depend on both the light exposure dose and the filler fraction. We determine that the degree-of-cure increases with increasing filler fraction for constant exposure dose, and approaches 90% with increasing exposure dose, independent of the filler fraction. The geometric accuracy of the 3D printed specimens decreases with increasing exposure dose and with increasing filler volume fraction due to so-called profile broadening. Finally, we show that the average surface roughness of the 3D printed specimens decreases with increasing exposure dose and filler fraction. This work has implications for VP of photopolymer resins with high filler fraction.

As the existing steel infrastructure inevitably continues to age and deteriorate, engineers are increasingly looking for innovative and effective methods for repairing and maintaining existing structures. Structural steel components can degrade due to the surrounding environmental conditions, and are susceptible to corrosion damage when exposed to aggressive environments and deicing salts. The conventional methods for repairing steel structures can be labor-intensive and time-consuming, and add considerable weight to the existing structure. One alternative is utilizing carbon fiber reinforced polymers (CFRP). Many studies have documented the ability of CFRPs to enhance the strength of existing structures. Furthermore, CFRP offers the benefits of being non-corrosive and having a high strength-to-weight ratio. Most studies on steel strengthening have focused on the bond behavior of CFRP to steels having a smooth surface condition, which are not representative of deteriorated structures in greater need of retrofitting. Further research has examined the durability of CFRP-steel bonds relative to environmental conditions that do not reflect the service life conditions for typical applications. In this work, a comprehensive study is conducted on the effects of the surface condition and environmental exposure on the bond between CFRP and steel. The influence of corrosion and simulated corrosion pitting is evaluated to determine whether structures with non-uniform surfaces are adequate for CFRP retrofits. In addition, the durability of CFRP-steel bonded systems is investigated through laboratory hygrothermal aging and in-situ environmental conditioning to multiple environments in Virginia. The research can be useful in the development of guidelines that will assist engineers determine if a CFRP retrofit solution is applicable in a given environmental setting and appropriate for the level of deterioration of the structure.

Machining of titanium alloys such as Ti-6Al-4 V can be very intimidating due to their low thermal conductivity leading to elevated cutting temperatures at the chip-tool interface (ICT). In this regard, the self-lubrication effect of coatings like TiSiVN represented by topography, oxidation, and diffusion at the chip-tool interface are crucial. Thus, the present work investigates the latter three mechanisms during dry machining of Ti-6Al-4 V titanium alloy with uncoated and TiSiVN coated Al2O3/SiC whiskers-reinforced ceramic cutting tools. The results reveal that the adhesion height (AH) and O% increases with cutting temperature, showing the dominant influence of cutting temperature on material adhesion and oxidation levels at the ICT. AH increases with increased cutting speed for both coated tools, indicating that the crater depth increment was not so severe for the coated tools. However, a drastic upward surge of crater depth for uncoated and TiSiN coated tools at 125 m/min cutting speed makes the crater edge near the ICT act as a chip breaker and facilitates the chip's bending away from the tool face causing reduction in chip bend angles (BA). Additionally, the TiSiVN coating accounts to a reduction of approximately 23% in AH and 18% in Ti%, and 37% lower oxygen levels at the highest cutting speed when compared to the uncoated tool primarily due to lower cutting temperatures and self-lubricating behavior.

The research presented in this thesis focuses on the receptivity to surface roughness of swept wing boundary layers dominated by crossflow instabilities (CFI), providing insights into how surface roughness can be used to passively control the developing instabilities. Discrete roughness elements (DRE) arrays and distributed randomized roughness patches (DRP) are employed to investigate the physical phenomena governing receptivity and their impact on CFI onset. The supporting data combine numerical solutions of linear and non-linear stability theory with advanced experimental flow diagnostics. This booklet is divided into three main parts. The first part investigates the flow mechanisms dominating the receptivity of stationary CFI to the amplitude and location of DRE arrays. The relation between the external forcing configuration and the initial instability amplitude is investigated, along with scaling principles allowing for the up-scaled reproduction of the swept wing leading-edge configurations, which provide experimentally observable configuration. The second part of this research explores the stationary CFI receptivity to specific up-scaled roughness configurations, including both isolated discrete roughness elements and DRE arrays. These roughness elements are applied at relatively downstream chord locations to enhance the experimental resolution of the near-roughness flow field. The isolated discrete roughness elements ensure strong boundary layer forcing, which helps to outline the relation between the near-element instability onset and the rapid transitional process. In contrast, the applied DRE arrays configurations provide boundary layers dominated by the development of CFI. In such scenarios, high-magnification tomographic particle tracking velocimetry identifies the dominant near-element stationary instabilities precursor to CFI. Specifically, the presence of transient growth and decay mechanisms in the near-roughness flow regi, Aerodynamics

Our awareness of ice caps’ and mountain glaciers’ sensitivity to climate change has driven major advances in the application of remote sensing techniques during the past decade. Regarding ESA’s SARIn altimeter CryoSat-2, processing the full waveform to generate swaths of elevation estimates has become standard practice in regions of complex topographies. This technique provides information on areas where we would be blind otherwise. In this article, we discuss systematic errors and analyze their impact on surface elevation measurements and change rates of two test areas. In particular, we focus on periodically occurring errors in elevation swaths, caused by the superposition of coherent signals from range-ambiguous surfaces. They can lead to measurement errors in excess of 10m, affect most measurements in mountainous regions, are difficult to exclude with established post-processing techniques, and occur repeatedly for satellite revisits introducing a 369-day periodicity—difficult to distinguish from the annual cycle. We show a correlation between derived elevation swaths and the sensor view angle and explore the influence of common data exclusion choices on higher-level products. Our results indicate that these systematic errors hold a substantial share of the error budget and that the choice of thresholds impacts higher-level products. We conclude that error correlations need to be considered to characterize the data accuracy. With the established data editing strategies, systematic errors prevent resolving seasonal mass changes of single mountain glacier basins and impact aggregates over larger areas or longer periods., Physical and Space Geodesy

This work focuses on the development of a novel method for joining and residue-free separation of polymer surfaces that support polymer recycling and enables the bond-ing of incompatible polymers. The technology presented employs polymer surface modification to generate functional groups that enable reversible joining through intermolecular interactions between two rigid, macroscopic polymer surfaces. The research consists of four segments, each emphasizing distinct elements of the join-ing process. The first section, which deals with the contact mechanics and adhesion of macro-scopic surfaces, deepened the understanding of the interactions between polymer surfaces by analyzing topographically defined polystyrene surfaces produced via hot pressing. Using atomic force microscopy and a specially developed measuring clamp, surface adhesion was investigated in relation to topography and oxygen plasma treatment and compared with established adhesion models (Johnson-Kendell-Roberts and Pastweka-Robbins adhesion criterion). It was determined that these models inadequately represent complex polymer surface interactions and are only conditionally suitable for predicting polymer adhesion. Thus, model modifications are required, to which the presented techniques could contribute. In the second section, the potential of low-pressure plasma treatment for modifying polystyrene and polyamide 12 surfaces was examined. By introducing functional groups into the polymer surface, the surfaces could be firmly bonded together by pressing without the use of adhesives. However, with water as a trigger, the bonds could be dissolved again within seconds. This separation mechanism suggests that the joining forces could be mainly based on hydrogen bonds. After dissolving the bond in water, the surfaces could be reconnected by renewed plasma treatment. The third section investigated the role of acrylic acid and copper(II) ions on the adhe-sion and separation of bonded polystyrene surfaces. Oxyg

Aquest Treball Final de Màster fa una anàlisi comparativa del comportament de dos materials utilitzats en la tecnologia de Fabricació Additiva d’Extrusió de Material, el CPE i el TPU, en la rugositat superficial i les toleràncies geomètriques. L’experiment s’ha dissenyat segons la tècnica de Disseny d’Experiments de Superfície de Resposta, avaluant l’alçada de capa (H), el nombre de parets que conformen la superfície de la peça (N) i el percentatge d’infill utilitzat (I), a més de diverses característiques geomètriques i del procés de fabricació: la màquina utilitzada (E), l’angle que la superfície avaluada forma amb el pla horitzontal (A), l’orientació de la peça dins el volum d’impressió (X), i el gruix de diversos elements geomètrics de la proveta (G). Finalment, també s’han considerat les diferències entre ambdós materials mitjançant el paràmetre M. En total s’han fabricat 80 provetes. Per tal de quantificar la rugositat s’han pres mesures de Ra i Rz, i l’anàlisi de les toleràncies geomètriques ha avaluat la circularitat, regularitat, concentricitat, paral·lelisme, perpendicularitat, planitud i angularitat. Els resultats d’aquest estudi mostren que la rugositat depèn, en ambdós materials, de l’angle de la paret (A), l’alçada de capa (H) i del nombre de parets (N). En el cas del TPU, a més, apareix una correlació amb el percentatge d’infill (I). S’han pogut avaluar amb confiança estadística les toleràncies geomètriques de circularitat, perpendicularitat i angularitat. En aquests casos la correlació apareix entre aquests tres paràmetres i el nombre de parets (N), la màquina utilitzada (E) i l’orientació de la peça (X)., Este Trabajo Fin de Máster hace un análisis comparativo del comportamiento de dos materiales utilizados en la tecnología de Fabricación Aditiva de Extrusión e Material, el CPE y el TPU, en la rugosidad superficial y las tolerancias geométricas. El experimento ha sido diseñado según la técnica de Diseño de Experimentos de Superficie de Respuesta, evaluando la altura de capa (H), el número de paredes que componen la superficie de la pieza (N) y el porcentaje de infill utilizado (I), además de varias características geométricas y del proceso de fabricación: la máquina usada (E), el ángulo que la superficie evaluada forma con el plano horizontal (A), la orientación de la pieza dentro del volumen de impresión (X), y el grosor de varios elementos geométricos de la probeta (G). Finalmente, también se han considerado las diferencias entre ambos materiales mediante el parámetro M. En total se han fabricado 80 probetas. Para cuantificar la rugosidad se han tomado medidas de Ra y Rz, y el análisis de las tolerancias geométricas ha evaluado la circularidad, regularidad, concentricidad, paralelismo, perpendicularidad, planitud y angularidad. Los resultados de este estudio muestran que la rugosidad depende, en ambos materiales, del ángulo de la pared (A), la altura de capa (H) y el número de paredes (N). En el caso del TPU, además, aparece una correlación con el porcentaje de infill (I). Se han podido avaluar con confianza estadística las tolerancias geométricas de circularidad, perpendicularidad y angularidad. En estos casos la correlación aparece entre dichos parámetros y el número de paredes (N), la máquina usada (E) y la orientación de la pieza (X)., This Master’s Degree Project does a comparative analysis of the behaviour of two materials used in the Additive Manufacturing technique Material Extrusion, CPE and TPU, in surface roughness and geometric tolerances. The experiment has been designed according to the Design of Experiments Surface Response technique, evaluating the layer height (H), the number of walls that form the surface of the piece (N), and the percentage of infill used (I), as well as various geometric and manufacturing characteristics: the machine used (E), the angle between the evaluated surface and the horizontal plane (A), the orientation of the piece within the build volume (X), and the thickness of some geometrical elements of the test sample (G). Finally, the differences between the two materials have also been considered, through the use of the parameter M. In total, 80 test samples have been built. To quantify the surface roughness, measurements of Ra and Rz have been taken, and the analysis of the geometric tolerances has evaluated the circularity, regularity, concentricity, parallelism, perpendicularity, flatness, and angularity, The results of this study show that the surface roughness depends, in both materials, on the angle of the wall (A), the layer thickness (H), and the number of walls (N). In the case of TPU, additionally, a correlation has been detected with the infill percentage (I). The geometric tolerances of circularity, perpendicularity and angularity could be evaluated with statistical confidence. In these cases, the correlation appears between said three parameters and the number of walls (N), the machine used for manufacturing (E), and the piece orientation (X).

The influences of surface roughness and shear processes on fluid flow and solute transport through three-dimensional (3D) crossed rock fractures, a vital element of fracture networks, were systematically investigated. Surfaces of tensile fractures created by splitting granite and sandstone samples along its two orthogonal central axes were optically scanned to generate rough-walled crossed fracture models. Shearing processes on the models were realized by assigning experimentally measured normal and shear displacements to one fracture while fixing the other. Fluid flow and solute transport through the models were numerically simulated taking into account different combinations of inlets and outlets, in which distilled water and solution are injected into the two inlets, respectively. The results show that compared to the parallel-plate model, the rough-walled crossed fracture model exhibits obvious flow channelization and fluid redistribution at the intersection, significantly promoting the mixing. The shear process affects the mixing at the intersection as it induces dilation and geometric change of the intersection. Increasing shear displacement can either enhance or reduce the mixing depending on combinations of the inlets and outlets, and the mixing ratio is controlled by the aperture difference between two outlet branches and the surface roughness. Effects of surface roughness, shear displacement and shear-induced dilation on the mixing ratio are quantified, upscaling of which can be potentially useful for field-scale characterization of solute transport in fractured systems., QC 20230815

Additive manufacturing (AM), also known as three-dimensional (3D) printing, of polymer-based materials is growing as a time-efficient, economical, and environmentally sustainable technique for prototype development in load-bearing applications. This work investigates the defects arising from the processing in material extrusion-based AM of polymers and their impact on the part performance. The influence of raster angle orientation and printing speed on tribological characteristics, microstructure, and surface finish of acrylonitrile butadiene styrene (ABS) fabricated in a heated build chamber was studied. Comprehensive analysis with fractography and tomography revealed the formation, distribution, and locations of internal voids, while surface defects were studied with the topography analysis of as-printed surfaces. Surface roughness and tribological results show that printing speed can be optimally increased with a minimal impact on interlayer bonding and part performance. Increased printing speed allowed up to 58% effective reduction in printing time obtaining comparable mechanical properties at varying process parameters. 3D printed ABS exhibited dry sliding friction coefficients in the range of 0.18–0.23, whilst the maximum specific wear rate was 6.2 × 10−5 mm3/Nm. Higher surface roughness and increased printing speed exhibited delayed running-in during dry sliding, while insignificant influence was observed for steady-state friction and wear behaviors. The findings indicate that improved surface finish and reduced internal defects can be achieved with a controlled build environment allowing for higher printing speed. The observations in this study are evidence that 3D printing can be adapted for the sustainable manufacturing of polymeric components for tribological applications., Validerad;2023;Nivå 2;2023-03-21 (joosat);Licens fulltext: CC BY License

In the near future hydropower will be used to regulate intermittent energy sources, shallow water ways can then occur in close proximity to the power plants, where the bottom often consists of stones in a similar length scale as the water depth. The idea of this project, which has been initiated by Vattenfall R\&D, is to compare experimental measurements in a laboratory environment with numerical simulations with CFD, this to find a way to represent roughness structures where there is low relative submergence. For the measurements in the lab, gravel were attached to the bottom of a flume and the water depth were measured for different flow rates and a CFD model were calibrated against the measurement data. A conversion of the Manning coefficient, originating from experimental measurements to equivalent Sand-grain size used in the CFD to model the roughness has been proposed and has shown good predictions of the maximum water depth. To capture the entire flow field, it is not enough to just model the friction from the roughness, it needs to be resolved and it may be necessary to consider the influence by form drag.

This study has aimed to determine the effects of surface quality and pore size, obtained by different levels of hydrogen content of the liquid metal, on the fatigue behavior of an Al–7%Si–3%Cu–Mg casting alloy. Three surface conditions have been studied: as-cast rough, as-cast smooth, and standard machined and polished surface. The S–N curves have shown that surface roughness and hydrogen content individually impact fatigue strength. Surprisingly, the fatigue strength of machined and polished samples, which aligns with standard testing practices, is significantly reduced, compared to other conditions. Fatigue cracks have been observed to initiate at the pores just below the as-cast surface or on the machined surfaces. In all cases, pores have been observed to be surrounded by bifilms. Moreover, hydrogen content and roughness of the as-cast surface have been found to interact to determine the fatigue performance. These findings necessitate a re-evaluation of fatigue testing procedures for cast aluminum components.

Abrasive water jet machining (AWJM) is extensively beneficial in machining materials that are hard to cut. This investigation deals with AWJM of Nano SiC filled Epoxy reinforced with basalt-glass fiber hybrid composite. The composite is prepared by compression moulding technique. Experimental trails are performed to evaluate the impact of every process parameter on the responses i.e., surface roughness (Ra) and Material Removal Rate (MRR). The experiments are conducted by changing the standoff distance (SD), traverse speed (TS) and water pressure. The performance of the conducted experiment is analysed using a Swarm intelligence algorithm. Surface roughness and MRR are maximized by using the combination of optimum process parameter levels of 9.72 mm/min speed, 5.78 mm stand-off distance and 553 MPa jet pressure. Scanning Electron Microscopic (SEM) images are employed in detecting the morphology of machined surface and confirmed the presence of voids and fibre pull-out.

Additive manufacturing (AM), also known as three-dimensional (3D) printing, of polymer-based materials is growing as a time-efficient, economical, and environmentally sustainable technique for prototype development in load-bearing applications. This work investigates the defects arising from the processing in material extrusion-based AM of polymers and their impact on the part performance. The influence of raster angle orientation and printing speed on tribological characteristics, microstructure, and surface finish of acrylonitrile butadiene styrene (ABS) fabricated in a heated build chamber was studied. Comprehensive analysis with fractography and tomography revealed the formation, distribution, and locations of internal voids, while surface defects were studied with the topography analysis of as-printed surfaces. Surface roughness and tribological results show that printing speed can be optimally increased with a minimal impact on interlayer bonding and part performance. Increased printing speed allowed up to 58% effective reduction in printing time obtaining comparable mechanical properties at varying process parameters. 3D printed ABS exhibited dry sliding friction coefficients in the range of 0.18–0.23, whilst the maximum specific wear rate was 6.2 × 10−5 mm3/Nm. Higher surface roughness and increased printing speed exhibited delayed running-in during dry sliding, while insignificant influence was observed for steady-state friction and wear behaviors. The findings indicate that improved surface finish and reduced internal defects can be achieved with a controlled build environment allowing for higher printing speed. The observations in this study are evidence that 3D printing can be adapted for the sustainable manufacturing of polymeric components for tribological applications., Validerad;2023;Nivå 2;2023-03-21 (joosat);Licens fulltext: CC BY License

In this study, the influence of notches in the area of gigacycle fatigue is investigated. The presented study offers experimental fatigue results of smooth and notched specimens. Specimens were made of AW 7075 - T6511 aluminum alloy and have “v” shape notch with radii of 0.1, 0.2, 0.4, 0.8, 1.5, and 3 mm. The fatigue experiments were performed using an ultrasonic fatigue testing machine at 20 kHz test frequency. Fatigue properties of the material were studied and evaluated up to 10 billion cycles in the area of very high cycle fatigue. All fatigue tests were carried out under uniaxial symmetric tension/compression loading (R=-1) at room temperature. As-machined surface and fracture surface of smooth specimens and specimens with 6 different notch radii were observed under an SEM microscope. Results show that there is a strong influence of the manufacturing process on fatigue lifetime.

In this study, the influence of notches in the area of gigacycle fatigue is investigated. The presented study offers experimental fatigue results of smooth and notched specimens. Specimens were made of AW 7075 - T6511 aluminum alloy and have “v” shape notch with radii of 0.1, 0.2, 0.4, 0.8, 1.5, and 3 mm. The fatigue experiments were performed using an ultrasonic fatigue testing machine at 20 kHz test frequency. Fatigue properties of the material were studied and evaluated up to 10 billion cycles in the area of very high cycle fatigue. All fatigue tests were carried out under uniaxial symmetric tension/compression loading (R=-1) at room temperature. As-machined surface and fracture surface of smooth specimens and specimens with 6 different notch radii were observed under an SEM microscope. Results show that there is a strong influence of the manufacturing process on fatigue lifetime.

Selective laser sintering (SLS) is a well-established technology that is used for additive manufacturing. Significant efforts have been made to improve SLS by optimizing the powder deposition, laser beam parameters, and temperature settings. The purpose is to ensure homogeneous sintering and prevent geometric and appearance inaccuracies in the manufactured objects. We evaluated the differences in the surface roughness and grain size of curved objects manufactured by using upcoming SLS technology that features two CO laser sources. Our analysis was carried out on polyamide 11 (PA11), which is a sustainable biobased polymer that has been gaining popularity due to its high-performance properties: its low melting point, high viscosity, and excellent mechanical properties. By using a Taguchi experimental design and analysis of variance (ANOVA), we examined the influence on the surface roughness and grain size of the build setup, the presence of thin walls, and the position of the sample on the powder bed. We found significant differences in some surface roughness and grain size measurements when these parameters were changed.

Previous research investigated several influence factors on soil-material interface behaviour through interface direct shear tests. However, conventional shear tests typically use a metal shear box to obtain the stress-strain relationship, which does not allow for the corresponding particle image to be captured by a camera. In this research, Particle Image Velocimetry (PIV) technology was applied to analyse particle behaviour and contributed to a fundamental understanding of soil-material interface behaviour. Several modifications were made to the shear apparatus to enable the use of PIV technology, which then allowed for its application in engineering and fundamental design optimization. The fundamental research conducted in this study involved parametric studies to investigate several factors that can influence interface behaviour, including surface roughness, surface hardness, particle breakage, relative density and confinement condition. Additionally, a portable surface profile gauge and the Mohs scale were utilized to characterise the surface properties. Test results reveal that surface roughness and surface hardness have significant effects on soil-material interaction, particularly in terms of peak shearing strength. To capture particle behaviour in sequential frames, such as breakage, interlocking, movement, and rotation, several modifications were implemented to the shear apparatus, including the use of a symmetric loading system, custom-built transparent shear box, camera and illumination system. The application of a high-resolution Digital Single-Lens Reflex (DSLR) camera also enhanced the quality of the captured images. The research outcomes validated the four-stage model proposed in previous research and demonstrated that the development of shearing strength corresponds to particle interlocking. In comparison to the stress-strain relationship of the soil-material interface, it was observed that a rough surface resulted in increased particle interlocking, Thesis (PhD Doctorate), Doctor of Philosophy (PhD), School of Eng & Built Env, Science, Environment, Engineering and Technology, Full Text

Additive Manufacturing (AM), commonly known as 3D printing, represents manufacturing technology that creates objects layer by layer based on 3D model data. AM technologies have capabilities that provide engineers with new design opportunities outside the constraints of traditional subtractive manufacturing. These capabilities of AM have made it attractive for manufacturing components in the space industry., where parts are often bespoke and complex. In particular, Laser Powder Bed Fusion (LPBF) has attracted attention due to its ability to produce components with the part properties required for space applications. Additionally, the precision of the laser enables the production of innovative near-net shape and low-weight part designs. However, due to the powdered metal material, the LPBF process is categorised with rough surfaces in the as-built state. The extent and effect of surface roughness are closely linked to geometrical design variables, including build orientation, overhangs, support structure, and build parameters; hence the more intricate the design, the more difficult the removal of this roughness. Consequently, the as-built surface for most applications is too rough and could adversely affect proprieties, i.e., fatigue. Hence, practical Design for AM (DfAM) supports should be developed that understand how design factors, such as surface roughness, will impact a part’s performance. This thesis therefore presents literature reviews on research related to LPBF surface roughness and design support, exploring the trends in managing surface roughness and investigations on the characteristics of design support. Additionally, through a space industry case study, a proposed process involving additive manufacturing design artefacts (AMDAs) is considered to investigate and describe the relationship between design, surface roughness, and performance. The review found that, in general, research focuses on the relationship between surface roughness and LPBF build pa

Remotely sensed microwave radars provide the spatial and temporal coverage needed to improve our understanding of the relationship between moisture content and salt pan mineralogy and, ultimately, climate variability. Moisture content in the surface and near-surface crusts found in salt pan environments, such as salt pan, has a significant impact on the backscatter values recorded by synthetic aperture radar (SAR) systems. This is because moisture affects the dielectric constant and surface roughness of the saline surface, which in turn influences the amount of electromagnetic energy reflected back to the SAR sensor. Changes in backscatter values are attributed to seasonal and interannual variations in salar surface properties (dielectric constant and surface roughness) and correlate with variations in regional climate trends. To better understand the spatial and seasonal dynamics of a salt pan (also known as salar), this study interprets a series of Sentinel-1 SAR images collected over Salar de Pajonales, Chile between 01 January 2019 and 31 December 2021. A total of 171 images were collected at 6-day intervals and processed using the Alaska Satellite Facility’s Hyp3 pipeline. An image stack was compiled and a time series was explored with the open-source, cloud-based platform, OpenSARLab. The time series of a mixed evaporite-mineral surface (composite surface) revealed that seasonal changes in dielectric properties and surface roughness drive variations in backscatter values at Salar de Pajonales. Rougher surfaces had stronger backscatter values in areas with higher surface roughness, except in wet conditions when increased soil moisture led to higher dielectric properties and, consequently, increased backscatter values. Mean backscatter values varied across the salar, with greater variability for the composite surface. These results underscore the significance of both dielectric properties and surface roughness when interpreting SAR data in salt pan environments

The machinability of materials is highly affected by their hardness, and it affects power consumption, cutting tool life as well as surface quality while machining the component. This work deals with machining of annealed AISI 4340 alloy steel using a coated carbide tool under a dry environment. The microhardness of annealed and non-annealed workpieces was compared and a significant reduction was found in the microhardness of annealed samples. Microstructure examination of the annealed sample revealed the formation of coarse pearlite which indicated a reduction of hardness and improved ductility. A commercially CVD multilayer (TiN/TiCN/Al2O3/ZrCN) coated cemented carbide cutting tool was employed for turning quenched and tempered structural AISI 4340 alloy steel by varying machining speed, rate of feed, and depth of cut to evaluate the surface quality, machining forces, flank wear, and chip morphology. According to the findings of experiments, the feed rate possesses a high impact on surface finish, followed by cutting speed. The prominent shape of the serrated saw tooth chip was noticed at a higher cutting speed. Machined surface finish and cutting forces during turning is a function of the wear profile of the coated carbide insert. This study proves that annealing is a low-cost and economical process to enhance the machinability of alloy steel.

In the near future hydropower will be used to regulate intermittent energy sources, shallow water ways can then occur in close proximity to the power plants, where the bottom often consists of stones in a similar length scale as the water depth. The idea of this project, which has been initiated by Vattenfall R\&D, is to compare experimental measurements in a laboratory environment with numerical simulations with CFD, this to find a way to represent roughness structures where there is low relative submergence. For the measurements in the lab, gravel were attached to the bottom of a flume and the water depth were measured for different flow rates and a CFD model were calibrated against the measurement data. A conversion of the Manning coefficient, originating from experimental measurements to equivalent Sand-grain size used in the CFD to model the roughness has been proposed and has shown good predictions of the maximum water depth. To capture the entire flow field, it is not enough to just model the friction from the roughness, it needs to be resolved and it may be necessary to consider the influence by form drag.

Electrophotography is affected by several parameters, including printing machines and paper type, which determine the final quality of reproduction. For the investigation of those effects, tests were done on the three types of electrophotography printing machines and eight types of uncoated paper with different properties of weight, surface roughness, whiteness, brightness and opacity. Samples were printed with cyan, magenta, yellow and black toner under the standard, identical conditions. The assessment of standard print quality parameter (optical density) was done using spectrodensitometer Techkon Spectro Dens. At the same time, the paper substrates were characterized using the atomic force microscopy (AFM) as well as by spectrophotometric measurements (X Rite Eye-One, i1). Obtained results showed that the reproducibility significantly depends on the type of printing machine rather than optical and mechanical properties of paper.

Wettability is the fundamental parameter that influences the productivity of hydrocarbon reservoirs. The knowledge of this regarding shale formation is yet inadequate; thus, detailed analysis is essential for successful development of such reservoirs. The Early Cretaceous Sembar formations in the Lower Indus Basin, Pakistan, is considered as the key target for energy exploration; however, it exhibits large uncertainties due to the lack of data availability. Sembar shales hold significant hydrocarbon volumes rich in organic content; however, prior to this, no comprehensive research has been conducted to quantify the wetting behavior of these shales. Thus, precise information about the wetting behavior of Sembar shale formations is essential, as it is influenced by many factors. Therefore, in this study, we examined the wettability of Sembar shale samples by performing a suit of contact angle (CA) measurements. The CA measurements on shale samples were performed using different salt types (NaCl, KCl, MgCl2, and Reef Salt) and concentrations of 0.1 M and 0.5 M under ambient pressures and varying temperatures (25 - 50 °C). The CA was measured via air-brine and air-oil under prevailing pressure and temperature conditions. Subsequently, the sample morphology and surface topography were examined via field emission scanning electron microscopy and atomic force microscopy, respectively. The mineral compositions were obtained via X-ray diffraction studies. The results clearly show that the Sembar shale possesses a mixed wetting behavior. Under dry surfaces, they have large affinity to oil and deionized water in which the droplet spreads quickly on the sample surfaces. Conversely, the samples aged with n-decane and NaCl brines exhibited higher CAs than the untreated samples. Additionally, the CA measured by changing temperatures led to an increase for all brine droplets; the CA further increased as the concentrations of salts increased from 0.1 to 0.5 M. We then discussed the

In augmented virtuality, estimating object surface reflectance properties is important when rendering objects under arbitrary illumination conditions. However, faithfully estimating surface reflectance properties is difficult for objects having interreflections. The present paper describes a new method for densely estimating the non-uniform surface reflectance properties of real objects constructed of convex and concave surfaces having diffuse and specular interreflections. The registered range and surface color texture images were obtained using a laser rangefinder. In the proposed method, the light positions are first determined in order to take color images, which are then used to discriminate diffuse and specular reflection components of surface reflection. Surface reflectance parameters are then estimated based on an inverse global illumination rendering. Experiments were conducted to reveal the usefulness of the proposed method., ICPR 2004 : 17th International Conference on Pattern Recognition , Aug 23-26, 2004 , Cambridge, UK

Two-scale models are an effective tool to study mechanical problems in which features in a wide span of length scales must be considered. In the context of contact mechanics, however, this cannot be directly used due to a lack of scale separation, which results in a lack of representativeness of the local-scale results. In this work, a model is proposed that circumvents this issue by incorporating stochastically the variability of the local scale results into the global-scale problem. Several test cases are performed to show the performance of the model., Work funded in part by the Spanish Ministry of Science and Innovation through grant PID2021-126614OB-I00., Peer Reviewed, Postprint (published version)

Rotational abrasive finishing (RAF) is a new nano-finishing technique in which the finishing forces are applied to the workpiece by the opposite rotations of a stirring-blades and the workpiece. The RAF process allows for finishing the inner and outer surfaces of workpieces, particularly complex ones with axial symmetry. The present study aims to propose a new theoretical model to obtain deeper insights into the material removal mechanism, surface roughness prediction, and forces in RAF process. Since the abrasive-workpiece interaction is random and complex in nature in the RAF, some initial assumptions were considered. To validate the repeatability of the experimental results, the experiments were designed based on the Response surface method (RSM). To validate the new proposed theoretical model, a number of influential parameters were investigated. It was found that the stirring-blade speed (S), working gap (W), and abrasive grain size (A) had significant effects on Ra. The minimum surface roughness (Ra) was obtained to be 46.87 nm at a rotational speed of 600 rpm, a working gap of 1 mm, and grain size of 18 µm. The experimental results were relatively in good agreement with the theoretical results so that the maximum error was about 24%. This can be assumed that the most important explanation for the difference between the theoretical and experimental results can be attributed to the initial theoretical assumptions., Objectius de Desenvolupament Sostenible::9 - Indústria, Innovació i Infraestructura, Postprint (published version)

Viscoelasticity and roughness are among the possible causes of the adhesive hysteresis displayed by soft contacts. Viscoelasticity causes an increased effective work of adhesion due to stiffening of the contact, while roughness is responsible for elastic instabilities. Herein, we explore the interplay between viscoelasticity and roughness by simulating in two dimensions the retraction of a rigid cylinder, with wavy surface profile, from a viscoelastic half-space. The wave amplitude and length are varied to induce instabilities in the load–to–area response, while the retraction velocity is increased to promote viscoelasticity. Results show that, in the regime where viscoelasticity is confined to the edges of the wavy contact, the contributions of viscoelasticity and waviness to adhesive hysteresis are nearly independent and additive. At low retraction rates, the instabilities in the load-area curve typical of rough elastic contacts are suppressed by viscoelasticity: the contact stiffens to promote a stable decrease of the contact area with load. This occurs with a minimal change in work of adhesion. However, when the instantaneous limit is met at high retraction rates, mechanical instabilities appear., LN acknowledges funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement no. 681813)., Peer Reviewed, Postprint (published version)

Coolant is a substance that applied in a machining process for the efficient machining of materials. The application of coolants is based on the several factors including the types of machining process, workpiece material, cutting tool and cost. Coolant helps to dissipate the heat that can be generated during the machining operation, induce lubricating effects to decrease the friction caused by the interfaces of two surfaces, flush away chips and offer corrosion protection. With the right type of coolants used, the performance of machining applications and the attributes of workpieces can be remarkably enhanced. The objective of the study to provides a critical review on the mechanism of coolant penetration, functions, variety of coolants, cooling actions, effectiveness, applications, and the additives that alter the ability and properties of coolants. Furthermore, the critical review also addresses the new technology cryogenic machining that uses cryogenic gases as coolants instead of conventional coolants.

This work aims to investigate and assess the beneficial function and feasibility of nanofluids in minimum quantity lubrication (MQL) assisted machining. The goal is to develop newly generated CNT based nano hybrid cutting fluid and demonstrate its effect on surface roughness of Al alloy. Moreover, the fabricated nano hybrid cutting fluid will eventually reduce cutting fluid consumptions and maintain an eco-friendly environment. Three conditions were used to perform the machining process such as dry condition, conventional oil and Al_2O_3/CNT nanoparticle with EVO oil as base fluid. The lowest surface roughness achieved for nanofluid and the maximum surface roughness for the dry condition. In terms of looking for optimum parametric combination, Artificial Neural Network (ANN) and Response Surface Methodology (RSM) have been used. The ANN technique has proved its efficiency since its correlation coefficients, mean prediction errors (MPEs), and root mean square errors (RMSEs) are small compared to the RSM approach.

The effect of CO2 laser drilling on glass microballoon/epoxy syntactic foams are investigated in this study to optimize machining parameters to achieve a clean hole for various industrial applications. The epoxy matrix is reinforced with glass microballoons in concentrations of 0, 20 and 40 vol%. Cutting speed, laser power and additive percentage are input parameters for optimization. Kerf taper angle, surface roughness and ovality percentage are used as output responses to evaluate hole quality. For the optimization study, hybrid multi-criteria decision-making methods such as grey relational analysis and multi-objective optimization with ratio assessment methods are used, with equal weightage given to each output response. According to the study, low power and high speed produce better machining results such as a smaller kerf taper angle, lower surface roughness and a lower ovality percentage. Furthermore, a higher additive percentage is not appropriate for laser in epoxy/glass microballoon composite because it burns the area near the laser and increases surface roughness. © 2023 The Author(s)

The effect of CO2 laser drilling on glass microballoon/epoxy syntactic foams are investigated in this study to optimize machining parameters to achieve a clean hole for various industrial applications. The epoxy matrix is reinforced with glass microballoons in concentrations of 0, 20 and 40 vol%. Cutting speed, laser power and additive percentage are input parameters for optimization. Kerf taper angle, surface roughness and ovality percentage are used as output responses to evaluate hole quality. For the optimization study, hybrid multi-criteria decision-making methods such as grey relational analysis and multi-objective optimization with ratio assessment methods are used, with equal weightage given to each output response. According to the study, low power and high speed produce better machining results such as a smaller kerf taper angle, lower surface roughness and a lower ovality percentage. Furthermore, a higher additive percentage is not appropriate for laser in epoxy/glass microballoon composite because it burns the area near the laser and increases surface roughness. © 2023 The Author(s)

The machinability of materials is highly affected by their hardness, and it affects power consumption, cutting tool life as well as surface quality while machining the component. This work deals with machining of annealed AISI 4340 alloy steel using a coated carbide tool under a dry environment. The microhardness of annealed and non-annealed workpieces was compared and a significant reduction was found in the microhardness of annealed samples. Microstructure examination of the annealed sample revealed the formation of coarse pearlite which indicated a reduction of hardness and improved ductility. A commercially CVD multilayer (TiN/TiCN/Al2O3/ZrCN) coated cemented carbide cutting tool was employed for turning quenched and tempered structural AISI 4340 alloy steel by varying machining speed, rate of feed, and depth of cut to evaluate the surface quality, machining forces, flank wear, and chip morphology. According to the findings of experiments, the feed rate possesses a high impact on surface finish, followed by cutting speed. The prominent shape of the serrated saw tooth chip was noticed at a higher cutting speed. Machined surface finish and cutting forces during turning is a function of the wear profile of the coated carbide insert. This study proves that annealing is a low-cost and economical process to enhance the machinability of alloy steel.

The effect of CO2 laser drilling on glass microballoon/epoxy syntactic foams are investigated in this study to optimize machining parameters to achieve a clean hole for various industrial applications. The epoxy matrix is reinforced with glass microballoons in concentrations of 0, 20 and 40 vol%. Cutting speed, laser power and additive percentage are input parameters for optimization. Kerf taper angle, surface roughness and ovality percentage are used as output responses to evaluate hole quality. For the optimization study, hybrid multi-criteria decision-making methods such as grey relational analysis and multi-objective optimization with ratio assessment methods are used, with equal weightage given to each output response. According to the study, low power and high speed produce better machining results such as a smaller kerf taper angle, lower surface roughness and a lower ovality percentage. Furthermore, a higher additive percentage is not appropriate for laser in epoxy/glass microballoon composite because it burns the area near the laser and increases surface roughness. © 2023 The Author(s)

The machinability of materials is highly affected by their hardness, and it affects power consumption, cutting tool life as well as surface quality while machining the component. This work deals with machining of annealed AISI 4340 alloy steel using a coated carbide tool under a dry environment. The microhardness of annealed and non-annealed workpieces was compared and a significant reduction was found in the microhardness of annealed samples. Microstructure examination of the annealed sample revealed the formation of coarse pearlite which indicated a reduction of hardness and improved ductility. A commercially CVD multilayer (TiN/TiCN/Al2O3/ZrCN) coated cemented carbide cutting tool was employed for turning quenched and tempered structural AISI 4340 alloy steel by varying machining speed, rate of feed, and depth of cut to evaluate the surface quality, machining forces, flank wear, and chip morphology. According to the findings of experiments, the feed rate possesses a high impact on surface finish, followed by cutting speed. The prominent shape of the serrated saw tooth chip was noticed at a higher cutting speed. Machined surface finish and cutting forces during turning is a function of the wear profile of the coated carbide insert. This study proves that annealing is a low-cost and economical process to enhance the machinability of alloy steel.

The machinability of materials is highly affected by their hardness, and it affects power consumption, cutting tool life as well as surface quality while machining the component. This work deals with machining of annealed AISI 4340 alloy steel using a coated carbide tool under a dry environment. The microhardness of annealed and non-annealed workpieces was compared and a significant reduction was found in the microhardness of annealed samples. Microstructure examination of the annealed sample revealed the formation of coarse pearlite which indicated a reduction of hardness and improved ductility. A commercially CVD multilayer (TiN/TiCN/Al2O3/ZrCN) coated cemented carbide cutting tool was employed for turning quenched and tempered structural AISI 4340 alloy steel by varying machining speed, rate of feed, and depth of cut to evaluate the surface quality, machining forces, flank wear, and chip morphology. According to the findings of experiments, the feed rate possesses a high impact on surface finish, followed by cutting speed. The prominent shape of the serrated saw tooth chip was noticed at a higher cutting speed. Machined surface finish and cutting forces during turning is a function of the wear profile of the coated carbide insert. This study proves that annealing is a low-cost and economical process to enhance the machinability of alloy steel.

The machinability of materials is highly affected by their hardness, and it affects power consumption, cutting tool life as well as surface quality while machining the component. This work deals with machining of annealed AISI 4340 alloy steel using a coated carbide tool under a dry environment. The microhardness of annealed and non-annealed workpieces was compared and a significant reduction was found in the microhardness of annealed samples. Microstructure examination of the annealed sample revealed the formation of coarse pearlite which indicated a reduction of hardness and improved ductility. A commercially CVD multilayer (TiN/TiCN/Al2O3/ZrCN) coated cemented carbide cutting tool was employed for turning quenched and tempered structural AISI 4340 alloy steel by varying machining speed, rate of feed, and depth of cut to evaluate the surface quality, machining forces, flank wear, and chip morphology. According to the findings of experiments, the feed rate possesses a high impact on surface finish, followed by cutting speed. The prominent shape of the serrated saw tooth chip was noticed at a higher cutting speed. Machined surface finish and cutting forces during turning is a function of the wear profile of the coated carbide insert. This study proves that annealing is a low-cost and economical process to enhance the machinability of alloy steel.

In this work, the fatigue and cellular performance of novel superficially treated porous titanium dental implants made up using conventional powder metallurgy and space-holder techniques (30 vol.% and 50 vol.%, both with a spacer size range of 100–200 µm) are evaluated. Before the sintering stage, a specific stage of CNC milling of the screw thread of the implant is used. After the consolidation processing, different surface modifications are performed: chemical etching and bioactive coatings (BG 45S5 and BG 1393). The results are discussed in terms of the effect of the porosity, as well as the surface roughness, chemical composition, and adherence of the coatings on the fatigue resistance and the osteoblast cells’ behavior for the proposed implants. Macro-pores are preferential sites of the nucleation of cracks and bone cell adhesion, and they increase the cellular activity of the implants, but decrease the fatigue life. In conclusion, SH 30 vol.% dental implant chemical etching presents the best bio-functional (in vitro osseointegration) and bio-mechanical (stiffness, yield strength and fatigue life) balance, which could ensure the required characteristics of cortical bone tissue.