Theoretically Investigation On The Roughness Profile of The Machined Surface After Flank Milling

In this study, the roughness profile of a machined surface obtained via a flank milling process is thoroughly investigated through theoretical modeling and experimental demonstrations. First, the roughness profile of a machined surface generated by a single-tooth end milling cutter along a straight path is considered (without helical angle). The trajectory of a point on the cutting edge is constructed according to the cutting kinematics, and the roughness profile of the flank surface is theoretically extracted from the trajectory. The surface topography is constructed by integrating the roughness profile along the axial direction of the cutter. Based on the constructed roughness profile model, the effects of cutting parameters on the roughness profile are discussed, including those of the cutting speed, radial depth of the cut, and feed rate. In addition, the effects of cutter geometries including the cutter tooth number, tooth spacing angle, and helical angle on the roughness profile and surface topography are discussed. Further, roughness profiles are constructed for cutter feeds along different tool paths, such as round and curved paths. Finally, experiments are conducted to verify the method developed in this study. The results show that the roughness profile obtained from testing matches well with the theoretically modeled profile. Moreover, the methodology for constructing the roughness profile is compared to an existing approach, which shows that the method in this study is significantly faster.

Hull Roughness and its Effects on Planing Boat Performance

The effects of hull roughness on loss of speed at constant power are investigated. Vessel lifetime roughness profiles are postulated based on construction, coatings and maintenance. These are utilized to determine loss of speed and change in running attitude for planing boats. The formulations are directly applicable to any planing boat for which a lifetime roughness profile is constructed as presented. The approach to developing the speed/power predictions and the roughness profile is provided. This approach can be utilized to analyze the effects of roughness due to hull material utilized and quality of construction, roughness from paints and coatings and their method of application as well as damage to the coating during maintenance, deterioration of the hull structure material, as well as biofouling influenced by the type of antifouling paint or coating and method of application. It provides a means for investigating different magnitudes and scenarios of these causes of roughness rather than providing only example results.

Microhardness homogeneity of RBCs light-cured with a multiple-peak LED and surface characterization after wear

This in vitro study evaluated the effect of the beam homogeneity of a multiple-peak light-curing unit on the surface microhardness and the effect of toothbrushing wear on the microhardness, surface roughness, roughness profile, volume loss, and gloss retention of incremental and bulk-fill resin-based composites (RBCs). A LED light-curing unit (VALO) with four LEDs at the tip end (405, 445, 465A, and 465B nm emission peak) was used according to each manufacturer-recommended time to obtain disks (n=10) of six RBCs: Estelite Sigma Quick, Charisma Classic, Tetric EvoCeram Bulk Fill, Filtek Z250, Filtek Supreme Ultra, and Filtek Bulk Fill. Microhardness values were obtained according to each LED positioning of the light-curing unit on the top surface of the RBCs and were analyzed before and after toothbrushing regarding microhardness, surface roughness, roughness profile, volume loss, and gloss retention. Microhardness was considered homogeneous on the top surface regardless of the type of RBC or wavelength tested (p>0.05). Overall, toothbrushing did not reduce the microhardness of the RBCs but influenced the gloss values for most RBCs (p<0.001). Charisma Classic presented the greatest surface roughness and roughness profile after toothbrushing (p<0.05). Volume loss did not differ among RBCs (p>0.05). In conclusion, different wavelengths of the LED did not affect the top surface microhardness, regardless of the RBCs tested; and bulk-fill composites presented similar surface changes (microhardness, surface roughness, roughness profile, volume loss, and gloss retention) when compared to conventional composites after toothbrushing.

Experimental Investigation and Multi-Response Optimization of Machinability of AA5005H34 Using Composite Desirability Coupled with PCA

Minimum quantity lubricant (MQL) is an advanced technique in machining to achieve sustainability, productivity, higher precision, economic benefits, and a reduction in carbon footprints. The present research work aims to investigate the effect of the cutting process parameters of the end milling of AA5005H34 material under dry and MQL cutting environments. The key performance indicators of machining include the surface roughness profile, the material removal rate, and tool wear. Surface roughness parameters are measured with the help of the Mitutoyo surface roughness tester, and the cutting tool wear is measured according to the ISO 8688-2:1989 standard using a scanning electron microscope (SEM). Sixteen experiments are designed based on the Taguchi orthogonal array mixture design. Single responses are optimized based on signal to noise ratios, while for multi-response optimization composite desirability function coupled with principal component analysis is applied. Analysis of variance (ANOVA) results revealed that the feed rate followed by spindle speed, axial depth of the cut, width of the cut, and cutting environment are the most significant factors contributing to the surface roughness profile, material removal rate, and tool wear. The optimized parameters are obtained as cutting speed of 3000 rev/min, feed rate of 350 mm/min, axial depth of cut of 2 mm, and width of cut of 6 mm under an MQL environment.

Biosurface processing with role in improving the osseointegration of the oral implant

Introduction The osseointegration of the oral implant involves a close contact between the bone and the implant, an important feature that allows the optimal transfer of stresses from the implant to the bone. Achieving and maintaining tissue integration is ensured by a biosurface design with a role in reducing the effect of shear forces on the interface, which can stimulate osteogenesis and facilitate tissue remodelling. Numerous specialized studies describe the method of modifying the biosurface area generated by a certain topography, among them are those that attest to the role of roughness in increasing the number of cells that will adhere to a biosurface with a larger area. Methodology Research was performed in order to establish the influence of mechanical processing on the micro-roughness of the surface of the samples from the experimental bioalloy Ti10Zr. Atomic force microscopy (AFM), scanning electron microscopy (SEM) and fluorescence microscopy were used to evaluate the experimental results. Results The study presents the results on the micro-roughness profile and the values of the parameters that characterize the micro-roughness profile groups (2D and 3D) of the biosurfaces processed by grinding and very fine polishing. Aspects regarding the modification of biosurface morphology, compared to mechanical processing, acid corrosion and anodic oxidation, as well as the results regarding cellular behaviour (e.g. adhesion of osteoblasts) to experimentally processed biosurfaces are also presented. Conclusions The results of this experimental study together with those previously presented in “Controlled Changing of Implantable Bioinert Materials Biosurface “scientific paper compile a synthesis of information on the ability to modify the microtopography of the biosurface of the Ti10Zr alloy, by different ways in order to improve implant osseointegration.

Interaction between time-varying tone inharmonicity, fundamental frequency and spectral shape affects felt tension and timbral semantics

Musically induced tension has been the subject of thorough study in the music cognition literature but its relationship with timbre is still poorly investigated. This study examines how the dynamic variation of a tone’s inharmonicity may affect a number of auditory qualities, namely brightness, roughness and mass along with felt tension under different acoustical conditions (i.e., F0, spectral shape and type of inharmonicity). Fifty-six musically trained participants gave real-time continuous ratings on eight time-varying stimuli upon the aforementioned qualities. Static ratings over the initial purely harmonic parts of the stimuli were also obtained by a subgroup of the listening panel. The fundamental frequency exhibits the strongest influence on the responses of the four qualities, followed by the type of inharmonicity and the spectral shape to a lesser degree. The profile patterns of mass and brightness proved to be strong predictors for tension profile patterns while the roughness profile magnitudes show a significant main effect on the magnitude of tension profiles. Overall, these results demonstrate that time-varying inharmonicity affects continuous responses on both timbral semantics and tension, while indicating that felt tension may be influenced by underlying timbral qualities in a dynamic context.

The Behaviour of Fresh Concrete with Varying Coarse Aggregate Content at the Concrete-Steel Wall Interface

The interaction between concrete and steel occurs during concrete mixing and finishing processes, during filling of concrete moulds, formwork, composite columns and during pumping of concrete mixtures. More experimental investigation is required to predict variations in interface friction, as a result of the composition of the lubrication layer which depends on the composition of concrete. This study provides experimental results to allow for a better understanding of friction at concrete-steel interface, with changes in the coarse aggregate (CA) content in the aggregate mixture (AM). Friction tests on fresh concrete have been carried out using the BTRHEOM tribometer (Nantes, France) and the interface parameters were calculated on the basis of the interface friction between the concrete and the steel wall, through the ADRHEO software. The roughness parameters were measured along the length of the rotary steel cylinder of the tribometer. In addition, the roughness of new and modified metal form-lining in steel composite columns was also measured. Variations in the CA content in the AM in the 42 to 52% range had minimal effects on the yield stress of the interface. The viscous constant of the interface as measured with a tribometer decreased, when the roughness parameter Rt values of the rotary cylinder wall, which refer to the absolute vertical distance between the maximum profile peak height and the maximum profile valley depth along the sampling length, were in the 17.10 to 28.73 μm range. The roughness profile peaks’ asperity recorded, was higher for the worn metal form-lining and for the steel composite columns with the inner surface covered in rust, when compared to the rotary cylinder roughness profile. The hypothesis is based on the principle that a sufficient lubrication layer, with the required thickness of fine mortar is created at the interface between the concrete and the metal form-lining or steel composite column wall, when the CA content in the AM varies in the range from 42 to 52% and the wall roughness parameters (Rt) of these elements varies in the 15.00 to 30.00 μm range.

Biotribology in Arthroplasty: Worn Surfaces Investigation on Ceramic Hip Femoral Heads Considering Wettability

Ceramic-on-ceramic bearings for total hip replacement are considered the best choice to avoid problems such as osteolysis and wear, mainly related to soft bearings. The aim of this work was to investigate in a comparative way different kinds of ceramic femoral heads for total hip replacements from a biotribological point of view, discussing the results obtained in terms of topographies, presence of metal transfer (MT) phenomena, and wettability on their worn surfaces in a tribological framework. Different ceramic femoral heads derived from in vitro wear tests, retrieved form patients, and brand new total hip replacements were investigated. The patients group had an average age of 60 years (ranging from 27 to 83). In most cases, the cause of failure was aseptic loosening of the acetabular component. Roughness analyses were performed to measure the tribological surface evolution of the material; an SEM and EDS investigation on the explanted heads proves and quantified MT, while the wettability was measured through a novel optical laboratory set-up with the aim to furnish useful data in the framework of synovial lubrication phenomena acting in the tribosystem. For the average roughness measurements on explanted specimens were considered three parameters (Ra = the average area between the roughness profile and its mean line; Rt = the vertical distance from the deepest valley to the highest peak of the roughness profile; and Rsk = it is the skewness and it is a measure of the asymmetry of the amplitude distribution function. In other words, the skewness indicates whether a surface is dominated by peaks or by valleys) and their values were: Ra 0.22 ± 0.12 μm, Rt 34.5 ± 13.5 μm and Rsk −0.01 ± 11.3; on the new specimens we measured Ra 0.01 ± 0.001 μm, Rt 0.12 ± 0.09 μm, and Rsk = 5.67 ± 8.7; for the in vitro specimens they were Ra 0.05 ± 0.12 μm, Rt 0.71 ± 1.4 μm and Rsk 7.73 ± 20.6. The wettability angle measurements showed hydrophilic surfaces for all femoral heads considered in this study with small differences between the three investigated categories, allowing to discuss their effects on the biobearings’ lubrication phenomena.