Smooth Finish Research Articles

Impact of drilling parameters on the surface roughness of egg shell filled glass fibre/polyester composites

Abstract Glass fiber-reinforced polymers (GFRPs) are widely used in domestic applications such as doors, windows, and furniture, where drilling is a common machining process. The surface roughness of drilled hole walls is a critical factor, particularly in fastening applications, where smooth finishes are essential. This study explores the influence of drilling parameters on the surface roughness of GFRPs reinforced with different types of eggshell fillers viz.,un-carbonized, carbonized, and hybrid along with an unfilled variant. The research employs a Central Composite Design within the Response Surface Methodology (RSM) framework to investigate the effects of material type, spindle speed, feed rate, and point angle on surface roughness. Material type and point angle were treated as categorical variables, while spindle speed and feed rate were continuous, each with four levels, resulting in 16 experimental runs. The results showed that surface roughness values varied from 3.04 to 4.99μm, depending on the specific combination of drilling parameters. Statistical analysis using Analysis of Variance (ANOVA) confirmed that spindle speed and feed rate significantly impact surface roughness, with roughness increasing at higher speeds and feeds. Notably, the carbonized eggshell-filled GFRP variant achieved the lowest surface roughness. The study also developed a highly accurate regression model, validated through experimental data. The novel use of different variants of eggshell fillers in GFRPs provides a sustainable and effective way to enhance material properties. Further, conducting the drilling studies to observe the outcomes, offers potential industrial applications in the production of high-quality, durable composite materials.

Resemblance as a Passing Quality: Liotard, La Tour, and the Question of Le Faire in Eighteenth-Century Portraiture

Abstract According to Diderot, ressemblance was a central quality in eighteenth-century portraiture – and yet it was ultimately less important than the particular manner of execution, le faire. Bold brushstrokes, art critics agreed in Paris around 1750, not only enliven the subject, but also testify to the artistic enthousiasme, the genius of a painter. While Maurice-Quentin de La Tour perfectly served this ideal with his bravura pastel portraits, his greatest rival at the time, Jean-Étienne Liotard, decidedly turned against this ideal. Concentrating on Liotard’s programmatic painting The Breakfast (exhibited in the Académie de Saint-Luc’s Salon of 1752), this article compares the different pictorial concepts of Liotard and La Tour, illuminates the contemporary discussion on execution, and ultimately asks about the strategies Liotard devised in order not to be overlooked as the author of his paintings despite his smooth finish.

Complete denture palatal rugae design impact on satisfaction and quality of life.

To compare the impact of three complete denture palatal rugae designs on participants' satisfaction and oral-health-related quality of life. Complete dentures palatal rugea are usually polished to a smooth finish, which can affect the patient's adaptation. Roughening or keeping an opening in the rugae area to replicate the natural sensation of the palatal rugae has been suggested but lacks clinical evidence. This randomised crossover trial included participants with complete dentures randomly allocated to six sequences. Each sequence alternated between polished, roughened, and open rugae designs. Participants evaluated general and domain-specific satisfaction (eating, taste, speaking, phonetics, and ease of cleaning) on a 100-mm visual analogue scale. They also completed the Oral Health Impact Profile for Edentulous Patients (OHIP-EDENT) and indicated their preferred design at the end. Repeated-measure ANOVA compared satisfaction, and one-way ANOVA with Tukey's test compared OHIP-EDENT scores. Forty-two participants were randomised. Seven dropped out. General satisfaction ratings were comparable for the polished (Mean = 80.2, SD = 19.7) and roughened designs (Mean = 79.5, SD = 20.2). However, the open design had a significantly lower satisfaction rating (Mean = 41.1, SD = 32.2). OHIP-EDENT scores for the open design (Mean = 44.9, SD = 17.5) were significantly worse than those for the polished (Mean = 36.1, SD = 12.7) and roughened designs (Mean = 36.2, SD = 13.3). Two-thirds of the participants chose the polished design. One-third chose the roughened design; of those, 83% were first-time denture wearers. Complete dentures with polished and roughened rugae designs were perceived similarly. Both designs could be recommended based on the patient's preference. However, the open design should be avoided due to negative perception.

Low‐Roughness 3D‐Printed Surfaces by Ironing for the Integration with Printed Electronics

The roughness of 3D‐printed surfaces poses a challenge when integrating fused filament fabrication (FFF) printing with printed electronics, leading to inconsistencies and breaks in the circuit traces. To improve the surface roughness, an ironing toolpath is proposed. The ironing toolpath involves the hot nozzle going over the printed surface with finer line spacing, remelting the surface to fill gaps, and creating a smooth finish. For further optimization, various ironing parameters are investigated including flow, speed, line spacing, and temperature. A wide range of materials is tested, including commonly used low‐temperature filaments (polylactic acid, polyethylene terephthalate, acrylonitrile butadiene styrene) and high‐temperature filaments (polysulfone, polyetherimide, polyether ether ketone) suitable for integration with printed electronics and medical applications. To collect the extensive datasets, an automated measurement system is deployed. With this method, surface roughness reductions of up to 96.6% are achieved and significant trends are identified. Lastly, the integration of 3D printing with electronics is demonstrated by printing a high‐resolution strain gauge structure on top of an ironed surface and embedding it into fully printed tweezers which can be used in medical robotics. The insights on ironing extend beyond electronics and can also be valuable in other areas where low surface roughness of FFF‐printed parts is required.

The China-Pakistan economic corridor boosted tourism industry in pakistan and digitalization of society


 
 
 
 The China-Pakistan Economic Corridor (CPEC) is a massive undertaking worth more than $ 55 billion, as a result of which the proportionate relationship between Pakistan and China has reached new heights. CPEC should seek to build partnerships between Pakistan and the associations of roads, railway lines, and oil pipelines associated with energy, power, and other systems to ensure a lack of important energy to enhance the advance related to money in Pakistan. CPEC is a lucrative opportunity for Pakistan's moving industry. The CPEC is widely regarded as beneficial to Pakistan's transportation and tourism industries. Through improved structure and transportation, the formation of special currency zones, increased trade movement, and increased trade and trade, the CPEC will alter Pakistan's monetary and trading environment. It relies on individuals from both countries for crucial benefits through the CPEC because it is a tireless attempt with a sane and smooth finish. The main motivation behind this post is to gain knowledge in the advancement of normal appreciation of China's impetus for the revival of the Silk Road, as well as the benefits and challenges for economic movement that the CPEC can bring to border countries, especially Pakistan. An especially original duty will provide us a lot of room to dramatically foster various inventive hotbeds to undermine the idea of organizations and the overall travelers experience in these new traveler places.
 
 
 

Enamel surface roughness evaluation after debonding and residual resin removal using four different burs

: There is a risk of damaging the enamel surface and changing its original morphology during orthodontic bonding and debonding procedure. Research on better adhesive removal methods which can effectively remove the residual resin and restore it best, to its original form are continuing till now. Studies have shown that Stain buster bur creates a smooth enamel surface close to natural enamel when compared to other polishing systems. Recently a new bur called Adhesive Residual Removal bur was introduced by Dentarum company to achieve a smooth enamel finish after debonding. In this study I have compared the enamel surface roughness after debonding and polishing with 4 different polishing burs.The objective of this study is to compare and evaluate enamel surface roughness after debonding and evaluated using four different finishing and polishing systems.After debonding adhesive resin is removed from the buccal surface of 80 premolars. Based on the Bur used for polishing the tooth surface it is divided into four groups of 20 each. Group 1-Tungestine carbide system, Group 2-Enhance finishing and polishing system, Group 3-fiber reinforced stainbuster bur, and Group 4- adhesive residual remover bur. Quantitatively measurement was done with the help of surface roughness tester and qualitative measurement was done using scanning electron Microscope (SEM).Highest post-polishing roughness was observed in tungsten carbide bur (1.37 μm) followed by enhance pogo bur (1.05 μm), adhesive residual remover bur system (0.83 μm), and Stainbuster bur (0.72 μm) (p value < 0.05).The smoothest enamel surface was produced by Stainbuster bur that was close to the natural enamel followed by Adhesive residual remover bur, Enhance system, and tungsten carbide bur.

Machine-to-machine variability of roughness and corrosion in additively manufactured 316L stainless steel

Numerous studies on the corrosion response of metal AM have been conducted. Nonetheless, the specimens being tested are commonly ground or polished to remove the outer as-built surface. If metal AM is truly going to be employed as a transformative technology that can produce complex shapes that do not require traditional machining, then the material needs to be evaluated in the as-built state. The reality is that AM alloys have shown significant inconsistencies regarding as-built surface texture, topology, and residual stress. One metric that has shown significant unpredictability in the literature is the susceptibility to localized corrosion of typically passive alloys, such as stainless steel (SS). There are a large number of studies that have attempted to understand the corrosion response of metal AM materials, but these studies are typically performed on materials that have been printed on a single machine and often mechanically polished to a smooth finish. This study compares the corrosion response of as-built AM, laser-beam powder bed fusion (LB-PBF), 316L SS parts that have been fabricated on five different machines. The majority of this work focused on understanding the susceptibility to localized corrosion of AM metals with respect to machine-dependent variables, namely surface roughness, and build angle. Surface roughness data was collected using scanning white light triangulation, laser scanning confocal microscopy, and coherence scanning interferometry. The results show that there is significant variability (ptwo-tail < 0.05) in the susceptibility to local corrosion initiation of LB-PBF 316L SS samples built on different machines. Surface oxides were probed with electron dispersive spectroscopy and revealed that variations in local corrosion susceptibility likely arise from differences in the stability of the passive film caused by chemical segregation, unique microstructure, and tortuous roughness features at the as-built surfaces. The variability of roughness and corrosion properties from test samples printed on different machines was corroborated by property measurements performed at five different testing sites, proving reproducibility of the data. Most importantly, this study shows that if the as-built surface layer is removed through grinding or electropolishing the machine-to-machine variation observed in the corrosion susceptibility is reduced.

Machinability of plantation-grown Eucalyptus globoidea timber

ABSTRACT Eucalyptus globoidea is an emerging plantation species. Its naturally durable heartwood has the potential to be used for solid wood outdoor products. Good machinability of a timber is essential for solid wood processing but was unknown for E. globoidea. The ASTM D1666 standard was used to assess the machinability of E. globoidea and compared to that of Pinus radiata, the dominating resource for the local wood processing industry and well-known for its good machinability. This study showed that E. globoidea machined equally well or better than P. radiata in planing, boring, mortising, grooving, edging, and turning. Sanding E. globoidea (723 kg/m3) was not possible at the prescribed settings, whereas a smooth finish was obtained for the lower density P. radiata (461 kg/m3). Reducing the sanding depth resulted in a satisfactory sanding finish. Defects that determined the machine scores were identified. When boring, mortising and grooving E. globoidea timber, most defects were chipping caused by the tool exiting the piece. When edging, most care needs to be taken at the corner. The comparable machinability of E. globoidea and P. radiata according to ASTM D1666 indicated that the well-established P. radiata wood processing industry should be able to process E. globoidea.

Heritage Stone 9. Tyndall Stone, Canada’s First Global Heritage Stone Resource: Geology, Paleontology, Ichnology and Architecture

Tyndall Stone is a distinctively mottled and strikingly fossiliferous dolomitic limestone that has been widely used for over a century in Canada, especially in the Prairie Provinces. It comprises 6–8 m within the lower part of the 43 m thick Selkirk Member of the Red River Formation, of Late Ordovician (Katian) age. It has been quarried exclusively at Garson, Manitoba, 37 km northeast of Winnipeg, since about 1895, and for the past half-century extraction has been carried out solely by Gillis Quarries Ltd. The upper beds tend to be more buff-coloured than the grey lower beds, as a result of groundwater weathering. Tyndall Stone, mostly with a smooth or sawn finish, has been put to a wide variety of uses, including exterior and interior cladding with coursed and random ashlar, and window casements and doorways. Split face finish and random ashlar using varicoloured blocks split along stylolites have become popular for commercial and residential buildings, respectively. Tyndall Stone lends itself to carving as well, being used in columns, coats of arms and sculptures. Many prominent buildings have been constructed using Tyndall Stone, including the provincial legislative buildings of Saskatchewan and Manitoba, the interior of the Centre Block of the House of Commons in Ottawa, courthouses, land titles buildings, post offices and other public buildings, along with train stations, banks, churches, department stores, museums, office buildings and university buildings. These exhibit a variety of architectural styles, from Beaux Arts to Art Deco, Châteauesque to Brutalist. The Canadian Museum of History and the Canadian Museum for Human Rights are two notable Expressionist buildings. The lower Selkirk Member is massive and consists of bioturbated, bioclastic wackestone to packstone, rich in crinoid ossicles. It was deposited in a low-energy marine environment within the photic zone, on the present-day eastern side of the shallow Williston Basin, which was part of the vast equatorial epicontinental sea that covered much of Laurentia at the time. Scattered thin bioclastic grainstone lenses record episodic, higher energy events. Tyndall Stone is spectacularly fossiliferous, and slabs bearing fossils have become increasingly popular. The most common macrofossils are receptaculitids, followed by corals, stromatoporoid sponges, nautiloid cephalopods, and gastropods. The relative abundance of the macrofossils varies stratigraphically, suggesting that subtle environmental changes took place over time. The distinctive mottles—‘tapestry’ in the trade—have been regarded as dolomitized burrows assigned to Thalassinoides and long thought to have been networks of galleries likely made by arthropods. In detail, however, the bioclastic muddy sediment underwent a protracted history of bioturbation, and the large burrows were mostly horizontal back-filled features that were never empty. They can be assigned to Planolites. The matrix and the sediment filling them were overprinted by several generations of smaller tubular burrows mostly referrable to Palaeophycus due to their distinctive laminated wall linings. Dolomite replaced the interiors of the larger burrows as well as smaller burrows and surrounding matrix during burial, which is why the mottling is so variable in shape.

Analysis of the process of qualifying the welding technology of S355JR structural steel using the submerged arc welding method

This paper presents the issue of welding technology qualification using the example of structural steel S355JR with a plate thickness of 25 mm and 100 mm, bevelling V. The main objective of this work was to attempt to perform a full qualification of the submerged arc welding process in accordance with the requirements of PN EN ISO 15614. Particular attention was paid to the issue of the qualification of welding technology. The samples were subjected to non-destructive testing, i.e. visual and penetrant testing, as well as ultrasonic testing and heat treatment. This was followed by destructive testing, including macroscopic testing and hardness testing. According to the proposed procedure for the recognition of submerged arc welding technology, once the necessary tests had been carried out and the protocols with positive results had been obtained. The documentation had been completed, the analysis needed to obtain certificates of conformity for factory production control and welding quality was carried out.Submerged arc welding is often used for highly responsible butt joints, particularly when joining thick components. This has been achieved through the proper design of the preparation of the parts to be welded and the development of a welding technology that practically eliminates the pre-phase that occurs in traditional technology, thereby eliminating the risk of it affecting the quality of the welded joint.During the implementation of submerged arc welding, a number of technological problems were encountered. The first test joints contained many defects, i.e. sticking and slag inclusions inside the welds. In addition, obtaining welds with the correct profile and removing the slag from the weld groove was difficult. These obstacles were eliminated experimentally by carrying out successive tests using different parameters and welding groove geometries.The correct implementation of any welding process depends on its input parameters. These parameters include welding current, welding speed, welding current, wire diameter, welding voltage and many others. Submerged arc welding (SAW) is widely used in the industry for manufacturing as it is more reliable, provides deep penetration in the work, ensures a smooth finish on objects, and results in high productivity.The technology was developed for a company that manufactures control discs for steam turbines.

Parameter optimization and prediction of surface roughness in grinding using CNSL as a cutting fluid

Surface grinding is one of the versatile processes in manufacturing, performed to achieve a smooth finish and close tolerance. The process is associated with high temperatures which influence the workpiece surface integrity, surface finish, and dimensional delicacy because of complex thermal stresses and thermal deformation of the workpiece. The usage of a cutting fluid becomes inevitable to address these problems.Cashew nut shell oil is a non-edible vegetable oil that is eco-friendly and possesses some potential properties required for cutting fluid. In this study, cashew nut shell oil is tried as a cutting fluid and its performance is compared with the traditional synthetic cutting fluid in surface grinding of EN8 material. The cutting parameters with two levels considered are the type of cutting fluid, grinding wheel speed, grinding wheel grade, depth of cut, and workpiece speed with the surface roughness or finish as the output response. The design of experiments has been carried out using the factorial method to analyze the effects of factors on the response. Parameter optimization has been done to get the optimum cutting parameters for minimum surface roughness. A model for predicting surface roughness has been proposed and the optimum cutting parameters for minimum surface roughness have been obtained. Also, validation experiments have been performed at an optimal condition and selected three conditions to prove the proposed model’s accuracy and confirm the potentiality of the cashew nut shell oil as a cutting fluid. The results show that the performance of cashew nut shell oil as a cutting fluid is better as compared to the conventional synthetic cutting fluid in obtaining a better surface finish.

Evaluation of strength of self-compacting concrete having dolomite powder as partial replacement for cement

Now a day, the utilization of self-compacting concrete (SCC) has become popular in creating RC structures. Apart from self-compaction, SCC has got many advantages such as excellent flow ability, filling ability, smooth finish of surface, ease of work etc. The use of waste material in concrete is the area of having scope for researchers for many years. Use of waste material reduces the consumption of cement by construction sector. In this present experimental work, dolomite powder is used as fractional replacement material for cement. The cement in the SCC is replaced by dolomite at fractions of 10%, 20%, 30%, 40%, 50%, 60%, and 70%. Fly ash is also added to the mix at constant fraction of 18% of the cement. The strength of SCC is assessed by performing compression test, splitting tension test and bending test. The test results showed that the use of dolomite powder in SCC is advantageous up to 20% replacement fraction. It is also observed that the strength of DC40 mix (i.e the mix having Dolomite at 40% of cement) is almost equal to the strength of normal SCC. Even at 70% replacement level, the strength of SCC having dolomite achieved is 25 MPa. SEM images are analyzed to identify the spread of hydrated products.

Achieving a Smooth Surface Polystyrene Waste Recyclate in Hot-Melt Processing

Polystyrene is an aromatic hydrocarbon plastic material with applications in the packaging, food, and construction industries. As a packaging material, it protects items against shocks and acts as an insulator in the construction of buildings and food preservation. The polystyrene bowl for food packaging has become a convention in the food and pastries industry in Ghana due to its clean, lightweight, and insulation properties. However, the corresponding waste litters its environment, chocks gutters, and does not decompose. For this reason, we explored the hot melt recycling technique to convert the PS wastes into valuable plastic plates that finds application in the artifact and souvenir industry. The incorporation of a 20% v/w lauric fatty acid (LFA) into the material matrix blocked micro holes in the finished product and induced a smooth surface. Characterizations included experiments such as Fourier Transform-Infra Red spectroscopy, melting point determination, tensile testing, and scanning electron microscopy (SEM). Generated data displayed the absence of a chemical bond between the PS molecules and the LFA additive. However, the methyl chains of the PS molecules were miscible with the saturated dodecyl chains of the LFA additive. Hence, the LFA additive was held in place by weak intermolecular forces between its chains and that of the PS molecules. The measured melting point of the recycled plastic with LFA content (rPS20) fell between 84-142 °C. Mechanically, the tensile strength dropped with the addition of LFA. The LFA induced a smooth surface morphology finishing in rPS20.

Using Computer Vision for Monitoring the Quality of 3D-Printed Concrete Structures

Concrete 3D printing has the potential to reduce material and process waste in construction. Thus, it contributes to making the construction industry more sustainable through the use of digital-fabrication technologies. While concrete 3D printing is attractive due to its potential to realize complex designs, practical challenges include an increased chance of defects and deformities. Quality assessment of 3D-printed elements is essential for large-scale implementation. Workability of concrete is known to decrease with printing time and it impacts extrudability. It is usually visible in 3D-printed elements, with the lower layers having a smooth finish, while the top layers have cracks and discontinuities. A computer-vision-based quality assessment method is proposed in this paper using a two-bin Linear Binary Pattern textural analysis. Information entropy is used as the metric for measuring the texture variation within each layer and its changes over the layers are studied. A higher entropy value is found for layers having deformities. Finally, through the error-minimization technique, a threshold entropy value is calculated and, using this, the printed layers can be assessed and corrective actions taken. This paper contributes to developing a non-intrusive quality assessment technique for concrete 3D-printed elements.

GPP09 Presentation Time: 10:00 AM: Patient Specific Template-Based Hybrid Brachytherapy for Treatment of Gynecological Cancers

<h3>Purpose</h3> Interstitial vaginal and pelvic brachytherapy (BT) is standard of care in locally advanced vaginal cancers and pelvic recurrence of gynecological malignancies. An in-house automated design and 3D printing workflow for pre-plannable patient-specific cylindrical templates (PSCTs) for IC/IS HDRBT was used for 7 patients treated at BC Cancer - Kelowna. Insertion positions and dosimetry are compared for preplan and final plans, and the practicality of preplanning for IC/IS HDRBT of the vagina is discussed. This work demonstrates that patient-specific treatment techniques for gynecological brachytherapy can be implemented within the clinic at a low cost. <h3>Materials and methods</h3> Seven patients with primary or recurrent vaginal malignancies were treated with IC/IS HDRBT facilitated with a PSCT which guided the position of IC/IS needles. Patients underwent pelvic T2-MRI imaging at least 7 days before their procedure with a dummy cylinder inserted. To satisfy pre-planning goals, virtual needles orientations and dwell times were optimized and adjusted as needed until the final plan is acceptable (Figure 1). Plans were exported and 3D modeled automatically using in-house written software. PSCTs were 3D printed of PEEK, and post-processed to have a smooth final finish, as shown in Figure 1. Each needle was pushed to its final depth under abdominal ultrasound guidance after the cylinder was inserted. Post-insertion CT scans were registered to preplan MRI scans and contoured, and final plans were optimized before treatment using digitized final needle positions. Patient final plan (Figure 1) dosimetry and needle insertion statistics were calculated and compared to pre-insertion plans. <h3>Results</h3> The treated median HRCTV D90, V100, V150, V200, Bladder, Rectum, Sigmoid and Small Bowel D2cm³, were 110.8%, 96.7%, 52.8%, 28.0%, 18.0 Gy, 15.4 Gy, 11.0 Gy, and 12.9 Gy respectively. The median differences of the final treated plan (post-plan) to the preplan were 1.1%, -0.5%, 13.1%, 4.1%, 1.0 Gy, 0.8 Gy, 0.5 Gy, and -0.8 Gy respectively. The median insertion displacement of dwell positions for straight needles, curved needles, and overall was 1.3mm, 4.0mm, and 2.3mm, respectively. <h3>Conclusion</h3> 3D printed patient-specific templates for the guidance of interstitial high dose rate brachytherapy of the vagina can be used to preplan and deliver highly conformal IC/IS Vaginal HDRBT treatments. The PSCT provides a significantly easier IC/IS insertion procedure as compared to using an IC cylinder + grid or freehand needles. Patients whose HRCTV geometry was in one location extending away from the cylinder rather than wrapping around the entire vagina had improved dosimetric indices because the PSCT is geometrically constrained to only be able to fit a maximum number of needles, thus covering a wide range of directions and depths is more difficult as compared to treating a more directed region. It is possible to combine a PSCT with an IS grid template to have the advantages of both techniques. Compared to commercial IC cylinders, the PSCT is preferable, since the preplan allows for patient customization and trade-offs optimization before insertion. Since IS dwell positions are achievable through PSCTs, they achieve preferable dose to target versus OAR trade-offs. Compared to techniques using IS Grid needles, the PSCT facilitates lower interstitial needle lengths, and preferable insertion locations in the vaginal mucosa rather than through the perineum. These templates can facilitate higher quality treatment plans as compared to state of the art techniques, particularly for deep, localized, and top-of-vault lesions, improving target coverage, reducing OAR dose, reducing interstitial needle length and trauma in non-tumor tissue and improving confidence in needle insertion without intraoperative MRI or CT.

SLA Resins Modification by Liquid Mixing with Ceramic Powders Aiming at Mechanical Property and Thermal Stability Enhancement for Rapid Tooling Applications

Stereolithography (SL) additive manufacturing process provides increased dimensional precision, smooth surface finish and printing resolution range in the order of magnitude of 100 μm, allowing to obtain intricate 3D geometries. The incorporation of ceramic-based inclusions within liquid resins enhances the thermal and mechanical properties of the final 3D printed component while improving the surface finishing of the final parts; in this way, it expands the range of process applications and reduces the post-processing steps. The proposed approach investigates the bulk modification of commercial SLA resins mixed with ceramic powders of Al2O3 (grain size 1–10 μm) and SiO2 (grain size 55–75 nm) aiming to improve 3D printed parts performance in terms of mechanical properties, dimensional stability and surface finishing compared with pure, unmodified resins. The produced materials were used for the development of inserts for injection moulding and were examined for their performance during the injection moulding process. The addition of particles in the nano- and micro-range is being employed to improve parts performance for rapid tooling applications whilst maintaining 3D printing accuracy, thermal and mechanical properties as well as achieving a smooth surface finishing compared with unmodified resins.

Effects of Surface Roughness on Shock-Wave/Turbulent Boundary-Layer Interaction at Mach 4 over a Hollow Cylinder Flare Model

Although it is understood that surface roughness can impact boundary layer physics in high-speed flows, there has been little research aimed at understanding the potential impact of surface roughness on high-speed shock-wave/boundary-layer interactions. Here, a hollow cylinder flare model was used to study the potential impact of distributed surface roughness on shock-wave/boundary-layer interaction unsteadiness. Two surface conditions were tested—a smooth steel finish with an average roughness of 0.85 μm and a rough surface (3K carbon fiber) with an average roughness value of 9.22 μm. The separation shock foot from the shock-wave/boundary-layer interaction on the hollow cylinder flare was tracked by analyzing schlieren images with a shock tracking algorithm. The rough surface increased boundary layer thickness by approximately a factor of 10 compared to the smooth case, significantly altering the interaction scaling. Despite normalizing results, based on this boundary layer scaling, the rough surface case still exhibited mean shock foot positions further upstream more than the smooth surface case. Power spectra of the unsteady shock foot location data demonstrated that the rough surface case exhibited unsteady motion with attenuated energy relative to the smooth-wall case.

Influence of aspect ratio on flexural behavior of reinforced self-compacting concrete beams

Concrete is a quasi-brittle material whose basic mechanical properties are size-dependent. Due to simple substitution in profoundly congested support structures without experiencing any consolidation, non-segregation property, and smooth finishing, it could be an exceptionally great choice in the concrete industry. The research object is the size effect on the flexural behavior of reinforced self-compacting concrete (SCC) beams by varying depth, length, and span. The length to depth ratio (aspect ratio) was 3.88, 5.38, 8.75, 11.5, and 15.38. SCC trial mixes were technologically advanced using FA (FA) as filler material and conplast SP430 as Super-plasticizer (SP). The workability properties were determined via the T50 cm slump flow, slump flow, U-box, V-funnel, J-ring, and L-box tests. FA (30%) with SP (1.9%) is satisfied with all the requirements of SCC as per EFNARC guidelines, and the designed compressive strength of concrete was obtained as 30 MPa. A total of six beams with various sizes, such as depths of 100 mm, 150 mm, and 200 mm, and lengths of 900, 1700, and 2200 mm, were cast with 1.2% tensile reinforcement bars. Based on the depth effect of beams, the load-deflection behavior, flexural strength, ductility index, and stiffness were studied. It is revealed that there is a decrease in strength properties by increasing the depth of beams during the static load conditions. Beams with a length equal to 1700 mm reached the best performance. It was also found the most advantageous l/d proportion, in terms of mechanical performance, is equal to 5.38.

Moving from analogue to digital workflows in dentistry: Understanding undermilling and overmilling as detrimental factors in fabricating CAD/CAM crowns.

Due to the limitations caused by the specific dimensions of milling burs, milling machines may inaccurately fabricate restorations by either over-reducing or under-reducing restorative material, respectively known as "overmilling" and "undermilling". Overmilling occurs when the bur is unable to accommodate areas smaller than the size of the bur, especially at cusp tips and sharp line angles. This results in excess cement space and a weaker restoration. Undermilling occurs when small concavities are ignored by the larger milling bur, particularly at the margins. This results in inadequate seating of the restoration and open margins due to premature binding, which can lead to restorative failure. To prevent these processing errors, clinicians should ensure that all incisal edges and cusp tips are flattened and rounded, verify that there are no undercuts, and prepare teeth with 1mm thick, smooth finish lines. Furthermore, clinicians may use the preparation check and milling simulation step of computer-aided design/computer-aided manufacturing (CAD/CAM) software to confirm the preparation is adequate and the restorative design does not have potential areas that will lead to overmilling.

Development and optical 3D printing of acrylated epoxidized soybean oil-based composites with functionalized calcium silicate hydrate filler derived from aluminium fluoride production waste

In this study, novel photocurable biobased and biodegradable composites with functionalized fillers from industrial inorganic waste have been developed and applied in optical 3D printing technology. Hydrothermally synthesized calcium silicate hydrates from aluminium fluoride production waste were used as fillers in photoresins based on acrylated epoxidized soybean oil-based. The use of fillers synthesized from industrial waste led to an improvement in the mechanical properties of polymer composites compared to filler synthesized from impurity-free material. The high 3D printing accuracy, perfect layer adhesion, and smooth surface finishing of 3D objects printed with a commercial digital light processing (DLP) 3D printer were shown by the developed composites. The biodegradability of photocured polymer composites reached 19.6% in 60 days. The developed composites have the great potential to be a competitive alternative to conventional petroleum-derived ones and reduce the environmental impact.