Groove Shape Research Articles

Micro-Abrasive Air Jet Machining Technology for Fabrication of Helical Grooves on Bovine Bone

Biological bone screws play an important role in fixing fractures and bone defects. The machining of helical grooves on xenogenic materials is a key part of fabricating biological bone screws. The fabrication of helical grooves on bovine bone using micro-abrasive air jets was investigated in this paper. The helical groove shapes were classified and their formation mechanisms were studied. Analyses of the material removal mechanism and the effect of process parameters on the groove shapes were carried out. The results show that the helical grooves could be effectively machined using micro-abrasive air jets with a spring mask. The shapes of the helical grooves could be classified as U-, V-, and W-shaped. Cracks that propagated along the cement line may have led to the formation of a slot. Meanwhile, cracks that propagated in the interstitial lamella may have led to the formation of ridges. The slots and ridges resulted in the appearance of stripes on the groove bottom. The cracks propagated along the axial direction of the osteon at the same time as it propagated into the osteon, leading to the formation of dimples on the groove sidewall. The experimental method proposed in this study can be regarded as a suitable method to fabricate helical grooves on bones.

Increasing friction of tread rubber under lubrication by adjusting groove shape to control fluid flow

Increasing friction of tread rubber under lubrication by adjusting groove shape to control fluid flow

Optimization Design and Experimental Study of Solid Particle Spreader for Unmanned Aerial Vehicle

This study designed and investigated a solid particle spreader, as well as parameter optimization and experimental for a groove wheel, to mitigate the problems of low uniformity and poor control accuracy of solid particulate material UAV spreading. The discrete element method was used to simulate and analyze the displacement range and stability of each grooved wheel at low speeds. Furthermore, orthogonal regression and response surface analyses were used to analyze the influence of each factor on the stability of the discharge rate and pulsation amplitude. The results showed that the helix angle, sharpness, and length of the groove significantly influenced the application performance, whereas the number of grooves had no significant influence. The groove shape was eccentric, the helix angle was 50°, the length was 35 mm, and the number of grooves was 7. Additionally, the bench test results showed that in the range of 10–60 rpm, the relative deviation of the discharging rate between the simulation and bench test is from 0.47% to 10.39%, and the average relative deviation is 3.93%. Between the groove wheel rotation speed and discharge rate, R2 was 0.991, and the adjustable range of the discharge amount was between 3.68 and 23.43 g/s. The minimum and maximum variation coefficients of the average discharge rate among individual applicators were 1.01% and 2.79%, respectively, whereas the standard deviations were 0.09 and 0.46 g/s, respectively. In conclusion, the discharge stability and adjustable range of the spreader using the optimized groove wheel satisfied the requirements for solid particulate material discharge.

Design the bionic sucker with high adsorption performance based on Sinogastromyzon szechuanensis

Based on the observed micromorphology of the Sinogastromyzon szechuanensis, a groove morphology was designed on the sucker working surface. The length, width, and number of the grooved morphology were selected as the design factors for the bionic morphology. The bionic and standard sucker was fabricated using the mold method, and the sucker adsorption performance was tested. Compared to the standard sucker adsorption force on the substrate (33.20 N), the bio-inspired sucker adsorption force could increase by a maximum of 71.22 %. The change law of the adsorption force was the same as the change law of negative pressure holding time. The bionic sucker could form multiple micro-sealing cavities from the groove morphology while forming a normal sealing cavity with the substrate. The bionic sucker adsorption force was greater than that of the standard sucker. As the length and width of the groove increased, the micro-sealing cavity formed by the groove shape made it difficult to form micro-suckers during the adsorption process, and the adsorption force was affected. With the increase in the number of grooves, the number of micro-suckers formed between the morphology and the substrate during the adsorption process could increase, and the adsorption force was increased.

Modified Split Hopkinson Pressure Bar Experiments of Grooved Al-Sheet Stacks As Energy Absorption Materials for Thermal Battery

As a highly reliable energy storage, lithium thermal batteries have been used in variety of military applications including missiles and rockets. There have been several attempts to use thermal batteries in artillery platforms, however absorbing the shock emitted by artillery fire to protect the embedded electronic equipment has been a major challenge. In this study, we suggest that thin aluminum sheet stacks with fine grooves are effective materials for energy absorption. The materials’ energy-absorbing performance was assessed using a modified split Hopkinson pressure bar (SHPB). Impact momentum (I) and maximum impact acceleration (a max ), which are the two important energy-absorbing parameters, were measured from stress-time (σ-t) curves. These parameters were found to vary with groove shape, groove cavity fraction, and specimen thickness. By carefully examining appropriate groove designs, cavity fractions, and stack thicknesses, this work offers a viable method for creating a variety of aluminum sheet stacks that show decreased a max and I, particularly in dynamically pressurized artillery settings. Figure 1

Numerical simulation and experimental investigation on the thermal-fluid-solid multi-physical field coupling characteristics of wet friction pairs considering cavitation effect

The coupling characteristics of thermal-fluid-solid multi-physical fields are crucial in determining the operational performance and service life of wet clutches. However, the underlying mechanism behind the influence of cavitation effect on these coupling characteristics remains unclear. Therefore, we propose a numerical solution method for considering cavitation effect in the coupling characteristics based on the multi-physical field coupling platform MPCCI combined with ABAQUS and FLUENT. The distribution patterns and intercoupling relationships among temperature field, flow field, and stress-strain field are comprehensively analyze. The influence of relative speed, cross-sectional shape of oil grooves, and oil flow on the coupling characteristics is investigated. Experimental validation confirms that the proposed model accurately predicts temperature variation by accounting for cavitation effect. The temperature distribution of steel discs is notably affected by the cavitation effect, leading to an elevation in the maximum temperature and uneven distribution characterized by localized hot spots along the circumferential direction. Accounting for the cavitation effect reduces errors between calculated and experimental values of temperature rise. The convective heat transfer coefficient gradually decreases radially, with a more pronounced decrease in the cavitation region. An increase in relative speed and a decrease in oil flow both lead to greater cavitation volume, resulting in higher temperature of steel discs. Among three different cross-sectional shapes of oil grooves investigated, rectangular grooves exhibit larger areas affected by cavitation compared to triangular grooves. These research findings provide a theoretical basis and technical support for accurate prediction of thermal characteristics within high-power wet clutches.

Numerical and experimental analysis of Al/GFRP joint for optimization of adhesive bonding strength using response surface method by considering surface patterning of the joints

Nowadays, adhesive bonding of metals and composites is widely used in the aerospace, automotive and military industries. In the present research, the finite element analysis (FEA) and response surface method (RSM) are used to optimize adhesive bonding strength between aluminum (Al) and glass fiber reinforced polymer (GFRP). For this purpose, the influence of the parameters of joint type, groove shape, groove number, and groove angle was investigated on the bonding strength. The joint type includes Al/Al, Al/GFRP and GFRP/GFRP, the groove shape includes V-shape, square and concave, the groove number includes 1, 3 and 5 grooves, and the groove angle includes 0, 45 and 90°. In order to model the crack growth in the simulation of adhesive bonding, the cohesive zone model was applied. Finally, the optimal sample is fabricated to examine its strength in temperature-humidity environmental conditions. The results of simulation and optimization indicated that the bonding strength improved in Al/Al mode with one square groove at 0° groove angle. The stress-strain diagram obtained from the simulation and optimization results was in good agreement with the sample made under optimal conditions. Moreover, the tensile strength of the optimal sample at temperature-humidity conditions was higher than the tensile force of the sample without groove.

Signature investigation of misaligned jet in Pelton turbines due to flow obstruction in nozzle

Abstract This paper presents a part of the research works related to early stage fault detection and diagnosis of hydraulic turbines. The research works are currently focused on creating a database of the distinctive signals of the faults in the turbine through CFD investigations. The faults in the turbine are induced based on experience and literature review of the common sediment erosion patterns. In the case of Pelton turbines, erosion in the needle with ripple and groove shapes and wavy scales on the buckets are found to be the most common erosion patterns. This paper focuses on asymmetrical erosion patterns of buckets and the needle caused due to flow obstruction in nozzle and consequent misalignment of the jet. The partial blockage for CFD is modelled as a sector of an annulus distributed around the needle. Velocity, pressure, output torque and erosion rates on the needle and buckets are studied. By integrating the trend analysis with machine learning techniques, a real-time condition monitoring tool and procedure can be developed. Since a predictive maintenance of the turbines can be implemented, the outcomes of these research works can have a commercial value for sediment affected power plants globally.

An experimental study to evaluate the performance of variable-width channel cold plates for cooling rectangular Li-ion batteries

The limited cooling capacity of cold plates employing conventional channel designs represents a key obstacle in thermal management systems. The persistent growth of the thermal boundary layer and the uneven distribution of flow across the channels are the principal challenges encountered in this context. To overcome these challenges, this study aims to analyse a modified cold plate of obstructed variable-width channels that can improve the hydrothermal performance and temperature uniformity. Different shapes of pin fins and grooves with variable sizes that match the width of the variable-width channels are proposed. Specifically, four types of pin fins–grooves were used: ellipse, drop, rhombus and trapezoid. The traditional cold plate served as a basis for evaluating the performance of new designs of cold plates. In addition to the traditional cold plate, the four proposed designs of cold plates were manufactured from copper. Experiments were conducted with water as a working fluid under a laminar flow for a flow rate range of 0.004–0.04 kg s-1 and a discharge C-rate range of 1C–2C. Results indicated that the use of variable-width channels with all shapes of fins–grooves effectively contributed to improving the heat dissipation of the cold plate, accompanied with an increase in hydraulic pumping power. At the highest flow rate, the best improvement percentage in the Nusselt number of 82.5 % was achieved when trapezoidal pin fins–grooves were used; by contrast, the lowest pumping power increasing percentage of 33.2 % was obtained when elliptical pin fins–grooves were adopted. The best hydraulic/thermal performance was achieved when trapezoidal pin fins were utilised, with the highest figure of merit of 1.685.

The Gross Anatomical and Histological Features of the Humerus in African Green Monkeys (Chlorocebus sabaeus) from Saint Kitts and Nevis, West Indies

This paper presents a detailed gross description of all anatomical elements of the humerus in the African green monkey and provides comparative and differential elements on monkey osteology. The osteometric investigation adds value to the gross morphological investigation, adjoining metric data to the gross descriptive data set. An in-depth investigation of the microstructural aspects of the humeral bone tissue is provided, with qualitative and quantitative details and potential for diagnostic applications. Of the gross morphological elements described, several unique features specific to this species include the humeral head shape that presents with distinctive low convexity and caudal placement, the shape of the intertubercular groove, the less developed greater tubercle, and the disposition of the rotator cuff muscle insertion. Furthermore, the overall cranio-lateral curvature of the bone shaft was found to have a distinctive 154–155 degree of angulation of the diaphysis, and the well-developed medial epicondyle was observed with its distinctive medio-caudal retroflexion. The histological investigation was more indicative of a typical non-primate organization of the bone tissue, with laminar vascular and avascular structures combined with the presence of the secondary Haversian system involving a mixture of scattered and dense unorganized secondary osteonal structures. The histomorphometric investigation yielded metrical data for the secondary osteonal structures in terms of area (20,331 ± 5105 µm2), perimeter, and vascular canal area (64,769 ± 257 µm2).

Torque and heat transfer characteristics in Taylor–Couette turbulence with an axially grooved cylinder

To describe the aerodynamic and thermal effects in the flow between the slotted stator and rotor of electric motors, we have conducted direct and large eddy simulations using the lattice Boltzmann method. The flow between the stator and rotor is influenced by turbulence and Taylor–Couette (TC) vortices. Axial grooves (slots) are incorporated either on the stationary outer cylinder or the rotating inner cylinder. These groove shapes and numbers are designed based on the groove geometry of drive motors used in commercial electric vehicles. The radius ratio of the TC flow configuration in this study is 0.955, and the simulated bulk Reynolds numbers reach up to 21000 which corresponds to the Taylor number of Ta=4.63×108. The characteristics of torque and heat transfer are analysed by comparing cases with and without grooves. Regardless of the groove placement, it is suggested that while the grooved surface effects are not significant on torque and heat transfer performance at Taylor numbers Ta≤107, where Taylor vortices are still evident, the effects become pronounced at Ta≥108 as the flow transitions to the ultimate regime.

Investigation of the failure mechanisms of photocurable resins under explosive shock loads

Resin components produced by photocuring technology and 3D printing are commonly utilized as seals across various media owing to their flexible molding, precise structure, and excellent watertightness. Under certain specific conditions, it is necessary to detach the photocurable resin seals from the main body using explosive cord blasting. However, the mechanical performance of photocurable resins under explosive shock loads remains underexplored. This study aimed to explore the mechanisms underlying the destruction of photocurable resins by explosive cords in different environments. We conducted explosive shock experiments on photocurable resin specimens both in air and underwater and employed explicit dynamics software to simulate the damage process of the resin material. The experiments showed that a 10 mm thick specimen in air reached a critical fracture state under the equivalent explosive shock of the explosive cord, leading to adjustments in the constitutive parameters of the photocurable resin model in the simulations. In addition, the JH-2 strength and failure model was applied in AUTODYN explicit dynamics software to characterize the mechanical properties of the resin materials. The fluid–structure interaction method was utilized for modeling and simulating the shock process on photocurable specimens in air and water, clarifying the role of groove shape in the fracture state of the specimens and the failure mechanisms of the photocurable resin materials under explosive shock.

First report of the genus Bostocktrachys Hirschmann, 1979 from India (Acari, Mesostigmata, Uropodina, Trachyuropodidae) with the description of a new species and with note to the ontogeny of the genus

The first representatives of the genus Bostocktrachys Hirschmann, 1979 have been discovered in India and are described here as Bostocktrachys wisniewskii sp. nov. based on females, males and nymphs. The new species differs from its congeners on the basis of the shape of grooves on the dorsal shields, dorsal and ventral setae and dorsal and ventral culptural pattern. The second deutonymph and the first protonymph of this genus are presented and discussed.

Analysis of the directions of improving regular micro reliefs

The article analyzes the features of planar regular microreliefs with the shape of grooves, the axis of which lies in a plane that is parallel or coincident with the surface on which the microrelief is formed and can be described by a periodic function. It was established that the main parameter that determines the operational properties of a surface with regular microreliefs is the relative area of the microrelief. The hypothesis is put forward that the geometric shape of the grooves of the microrelief practically does not affect the operational properties of the surface. Microreliefs of groove axes that a periodic function can describe are technologically imperfect because when forming the tops of microrelief grooves, the tool must make stops to change the trajectory of movement. The complex geometry of microrelief grooves reduces the productivity of their formation, and the complexity of ensuring regularity ensures the surface's heterogeneous physical and mechanical properties. Directions for improving the forms of microreliefs are proposed, which will ensure an increase in the productivity of their formation and provide an opportunity to control the operational properties of the surface

Mechanical Properties and Microstructure Analysis of Mild Steel Welding Made by GTAW

This work discusses the effect of gas tungsten arc welding (GTAW) variables on the welding transverse tensile strength and hardness of S 235JR at different groove configurations. The welding microstructure and numerical fracture mechanism are also discussed. GTAW is increasingly emerging in the local industry due to its advantages over conventional shielded metal arc welding (SMAW). The properties of steel welding have always concerned manufacturers and researchers. Since steel structures experience forces such as tensile, it’s vital that good welding has increased tensile strength. It was reported that the hardness of welding affects the welding properties and, therefore, the integration of welded structures. The groove shape of the joining ends determines the size of the FZ and affects the dilution; thus, it is important to study the groove shape due to its effect on the final properties of welding. The results showed an increased welding traverse tensile strength (251 MPa) at higher welding speeds (150 mm/min) and V-shaped groove welding. The V-shaped groove welding that obtained higher tensile strength (251 MPa) has shown higher grain boundary ferrite and PF volume friction in the FZ and finer PF in the HAZ due to its higher interpass heat input. Higher traverse tensile strength welding has shown increased bainite and lower bainite volume friction in FZ and a finer grain structure in HAZ. The failure due to tensile force starts at the welding root, according to numerical analysis, and a double V-shaped groove has shown deformation balance at the tensile test.

Molecular dynamics study of the groove-forming mechanism of mechanically scratched grating multilayer aluminum films

For a long time, the forming quality of large area diffraction gratings is restricted by the one-time coating quality and uniformity of large thickness and large area aluminum films. Large thickness coatings, low accuracy of large depth grooves and diamond tool wear problems were the main reasons for the failure of the test to inscribe large area diffraction gratings. Therefore, the use of layered coating process can effectively ensure the uniformity and consistency of large-area and large-thickness grating blanks coated with aluminum film, and improve the high precision of large depth diffraction grating slot type. In order to reveal the mechanism of the groove-forming process of multilayer aluminum films, the microstructure and mechanical properties of different aluminum films were observed. In this article, the removal behavior and mechanism of nanomechanically scratched multilayer aluminum film materials are investigated using a molecular dynamics approach, and the characteristics of multilayer aluminum films scratched into grooves are analyzed in terms of surface morphology, scratching force, structural evolution, dislocation distribution, von Mises stress and shear strain. The results indicate that in the scratching simulation process, multilayer aluminum film has a higher number of removed atoms and a larger atomic displacement compared to single layer aluminum film, which is conducive to precise shape control of the groove. The average tangential force and normal force of multilayer aluminum film show a decreasing trend compared to single layer aluminum film, which helps to scratch grooves and reduce tool wear. The total length of the dislocation lines of the multilayer aluminum film is large, and the distribution area is large, which improves the precision of scratching the grooves. Therefore, an appropriate increase in the number of aluminum film layers has a precise control effect on the groove shape. This study has certain reference significance for analyzing the complex grooving deformation law of grating aluminum film, improving the diffraction efficiency of grating aluminum film, and further improving the manufacturing process of grating aluminum film.

Effect of rib profile on critical buckling pressure of ring-stiffened composite shells under hydrostatic pressure

ABSTRACT The buckling behaviour of thin-walled composite cylindrical shells with different rib profiles under hydrostatic pressure is studied in this paper. Various models of composite shells with outer diameter of 324 mm, thickness of 8 mm, length of 800 mm, and 18 different rib profiles are designed. Ribs have same sectional area and the total height is no more than 18 mm. Finite element (FE) models are built and validated by published experimental and FE results. The results for above models are obtained and show that the critical buckling pressure of ring-stiffened composite shells can improve by 44% to 136% compared to that of unstiffened composite shells. The rib total height, web thickness, and rib profile type are three factors affecting the critical buckling pressure of ring-stiffened composite shells. The composite shell stiffened by groove shape can acquire maximum buckling-carrying capacity.

Effect of structure tool on nano-cutting surface integrity of single crystal γ-TiAl alloy via atomic simulation

To investigate the impact of microgroove geometry at the tool's flank face on the surface integrity of the workpiece, molecular dynamics simulation is utilized to establish a model of cutting single crystal γ-TiAl alloy using various structured nanodiamond tools. The effect of groove shape on the surface integrity of single crystal γ-TiAl alloys was investigated by analyzing mechanical properties, workpiece surface quality, and subsurface damage during the cutting process. The results show that non-structured tool cuts γ-TiAl alloy with the highest cutting force, and the V-groove tool cuts with the lowest friction coefficient, which is favorable for the removal of single crystal γ-TiAl alloy. Statistical atomic phase transitions during cutting confirmed that structured tools reduce subsurface damage, especially V-grooved tool reduce the generation of defective atoms. The circular arc grooved tool effectively reduces the subsurface temperature of the single crystal γ-TiAl alloy workpiece by reducing the friction at the tool chip interface due to lower normal cutting force. In addition, the circular arc grooved tool cutting has stronger atomic flow and surface recovery ability compared with other tools, and smaller surface roughness can be obtained. Therefore, selecting a reasonable structured tool can effectively improve the machinability of single crystal γ-TiAl alloy.

Machinability improvement of titanium alloy in face grinding by ultrasonic assisted jet plasma oxidation

A novel machining technology, namely ultrasonic assisted jet plasma oxidation modification face grinding (UAJPMG), was proposed to improve the machinability of the titanium alloy, in which the titanium alloy materials are modified by plasma oxidation followed by face grinding. This paper introduced the processing principle of UAJPMG and the design of an ultrasonic jet nozzle to promote plasma oxidation. Using the ultrasonic jet nozzle produced in-house, the effect of the ultrasonic vibration on the plasma intensity was experimentally investigated. The results revealed that the application of ultrasonic vibration can diminish the thickness of the gas film by elevating the jet flow rate, thereby reducing the generation delay time and enhancing the plasma intensity. Subsequently, a scratch test was performed to assess the difference in the mechanical strength between the plasma oxide layer and the titanium alloy substrate. It was found that the plasma oxide layer with a reduced mechanical strength exhibited a deeper scratch depth under the same normal load. Based on these, the machining performance under different conditions was examined considering the removed material of the abrasive grains. Compared with the removed material was Ti-6Al-4V substrate in conventional face grinding, the ultrasonic assisted plasma oxidized material can inhibit the chip adhesion on the wheel working surface, resulting in a reduction of the grinding force and the surface roughness and an improvement of the groove shape accuracy. The novel machining technology, i.e., UAJPMG, proposed in this paper might provide a new approach for the precision machining of critical components made from titanium alloy.

Shape Optimisation of Grooves in Grooved Gusset Plate Damper used in X-Braced Frame

The X-braced frame represents a specialized variation of concentric-braced frames. It can be used as a resistance towards the lateral load acting on the structural system. X-braced frames generally exhibit lower flexibility when compared to eccentrically braced and moment frames, which is often perceived as a drawback of this structural system. To address this limitation, energy dissipation devices can be integrated into the system with X-bracings to absorb the plastic action and safeguard other structural elements, such as columns, beams and connections from earthquake forces. Specifically, X-concentrically braced frames are tailored through variations in groove shapes. Furthermore, the investigation determines the dampers' load-bearing and energy dissipation capacities. The assessment commences with cyclic load testing conducted using the ANSYS software. The grooves present in GGPD help dissipate seismic energy. The energy dissipation and load-bearing capacity of the X-concentrically braced frame equipped with a grooved gusset plate damper were compared based on different groove shapes. The different shapes used for the analysis were L shape, oval, rectangular and stadium shape. It was observed that oval-shaped grooves have more energy dissipation capacity among four groove shapes, with an increase of 10.74%.