Groove Design Research Articles

Prediction of the welding distortions of butt welded joints using total moments method based on equivalent loads

The paper presents a method of predicting welding deformations based on the results of experimental tests of transverse and longitudinal shrinkage, using finite element simulation using equivalent loads. The study also presents angular distortion tests of butt joints and the plate edge deformations resulting from these distortions. The tests were carried out in laboratory conditions for one of the basic conventional welding methods used in the shipbuilding industry, i.e. FCAW (V beveled), for various welding groove geometries. The main difference between the proposed method and other methods using equivalent load is considering the bead shape and groove design with the face and root reinforcements when calculating the moments (interacting in both directions). Good agreement of the results obtained on the basis of the proposed method (i.e. the method of total moments) with the results of experimental studies was shown. The presented method of welding deformation predicting has been verified against the existing method (i.e. Equivalent force method). The usefulness of the proposed method for predicting welding deformations arising during the assembly of the similar joint in another conditions was also shown.

Impact of gap size and groove design of hydrodynamic bearing on plasma skimming effect for use in rotary blood pump.

Plasma skimming can exclude red blood cells from high shear regions in the gaps formed by hydrodynamic bearings in rotary blood pumps. We investigated the effect of the gap size and groove design on the plasma skimming efficiency. Spiral groove bearings (SGBs) were installed into a specially designed test rig for in vitro experiments performed using human blood. The measured gap between the ridges of the bearing and the rotor surface was 17-26µm at a flow rate of 150ml/min and a rotor speed of 2400rpm. Three different patterns of SGBs were designed (SGB-0, SGB-30, and SGB-60) with various degrees of the circumferential component. The hematocrit measured by a high-speed camera was compared with the hematocrit in the circuit, and the plasma skimming efficiency for the three bearing patterns was evaluated at hematocrits of 20%, 25%, and 30%. SGB-60, which had the strongest circumferential component, provided the best plasma skimming efficiency. When the gap size was less than 20µm, the red blood cells in the gaps between the ridges of the bearing and rotor surface reduced significantly and the efficiency became higher than 90%. The gap size had the strongest effect on producing a significant plasma skimming. The plasma skimming efficiency can be significantly improved by optimizing the bearing gap size and groove design, which facilitates the further development of SGBs for use in applications such as rotary blood pumps.

Structural design and sand-discharge performance of the end-face groove of a cone bit

The sealing system of the roller cone bit indirectly determines the overall service life of the bit. However, the sealing part is one of the most easily damaged components of the roller cone bit. It can improve the sealing performance and service life of the bit and reduce the times of tripping during drilling. According to the results of the sealing failure analysis and the end-face position of the cone, the function of the end-face groove structure is defined as expelling most of the rock debris particles from the end face of the cone. The end-face sand-discharge structure is designed through theoretical analysis. Simulations are performed to study the performance of the end-face sand-discharge structure, verify the feasibility of the end-face sand-discharge structure, and obtain the effects of the structural parameters of the end-face sand-discharge structure on the performance of the structure. In the process, a new method of discrete phase particle tracking using simulation software is explored.

Theoretical and experimental exploration into the fluid structure coupling dynamic behaviors towards water-lubricated bearing with axial asymmetric grooves

The work studies the fluid structure interaction (FSI) dynamic behaviors of water-lubricated bearing with axial asymmetric grooves. Revised FSI models with consideration of cavitation and turbulent effects are put forward. Stimulations are consistent with the literature and experimental data, indicating the correctness of the model. Effects of groove types, locations in ascending/descending zones towards the dynamic behaviors are explored in details systematically. The separation effects of the local asymmetric grooves coupled with the rotation effects further enhances the hydrodynamic effects, which will directly lead to the growth of maximum pressure values and the load carrying capacity (LCC). Research fruits have important guiding significances for the optimization design of the surface microstructures and micro-textures, especially the design of axial asymmetric grooves for such bearings.

Gas film lubrication method on rotation shaft seal based on contact design

PurposeWear failure happens frequently in rubber seal of high-speed rotating shaft because of the dry friction. Some traditional lubrication methods are not effective because of the restrictions on the relative high speed, temperature and others. This paper aims to present a new method of lubrication with gas film for the rotation shaft seal based on the contact design.Design/methodology/approachTo obtain the generation condition of gas film and good effect of lubrication in the contact gap between the shaft and its seal, a series of micro-spiral grooves are designed on the contact surface of rubber seal so as to obtain a continuous dynamic pressure difference.FindingsThe result is that the distribution of the gas film in the micro-gap is continuous under the design of the spiral grooves and the contact with eccentricity because of the deformation of rubber seal, which is verified through the simulation calculation and experiment test. It is confirmed that the lubrication method with gas film through designing micro-spiral grooves on the contact surface is effective, and can achieve self-adaptive air lubrication for the high-speed shaft under the premise of the reliable sealing.Originality/valueThe method of gas film lubrication is realized through designing a microstructure of spiral grooves on the rubber surface to change the contact status, which can form a mechanism of adaptive lubrication to reduce the dry friction automatically in the contact gap. For the cross-scale difference between the rubber seal and gas film, a new modeling method is presented by building the mapping relation for the split blocks and repairing technique with integrated computer engineering and manufacturing, to reduce the possibility of nonconvergence and improve the efficiency and accuracy of calculation.

Deformation control during the welding of AP1000 main pump casing and steam generator

• The AP1000 main pump casing and SG outlet nozzle have strict requirements on alignment precision. • A special RCP bracket is needed for precise assembling. • The joint between pump casing and SG should be TIG welded with different alloy materials. • The first few layers of welding have great influences on the pitch angle and the angle change. The welding of the AP1000 Reactor Coolant Pump (RCP) casing and Steam Generator (SG) is an important issue to maintain the integrity of pressure boundary. The position tolerance of pump casing nozzles after welding will directly affect the internal components of the main pump, as well as the on-site assembling processes. This article investigated the method of controlling deformations during welding (such as assembly alignment, groove design, welding process control, etc), in order to prevent excessive welding deformation and therefore extra discrepancies during pump casing positioning. In this paper, we have developed a welding process, which can allow the installations of AP1000 pump casings to meet all nuclear grade requirements.

Dynamic characteristics improvement of the single screw compressor with odd-grooves screw rotor

Recently, the single screw compressor (SSC) has been applied in the low-temperature heat pump system with the purpose of achieving higher system efficiency. However, the traditional SSC with even-grooves screw rotor behaves high torque fluctuation to the motor, thanks to its work synchronously and doubled compressed gas-induced torque on the screw rotor axis. It is more serious in the low-temperature heat pump system because of the higher pressure ratio. In this paper, an odd-grooves screw rotor design is proposed to smooth the compressed gas-induced torque on the screw rotor axis, by arranging the two compression chambers work alternatively. A dynamic model for the screw rotor is established to calculate the gas force and the gas-induced torque on screw rotors under different working conditions. The results show that the odd-grooves screw rotor design can remarkably reduce the gas-induced torque fluctuation of the SSC. Meanwhile, the maximal load on the bearing caused by the odd grooves design could be controlled below the maximum allowable load of the bearing.

Profile Design of the Grooved Die and Rolling Force Prediction in the Cold Pilger Rolling Process

The objective of this study was to design the die groove profile and predict the rolling force produced when employing the variable curvature rolls and mandrel for manufacturing seamless pipes using the cold pilger rolling process. The parameters of the key process design were the diameter of the initial tube and final product, as well as the feed amount, reduction area, principal deformation zone, and roller radius. The rolling forces during the pilger rolling process were theoretically calculated to enable their prediction, and the characteristics of the cold pilger rolling process were identified. The calculated values were in close agreement with the experimental data. The die groove design is important in the prediction process because the dimensional accuracy of the tubes and the life of the dies are highly dependent on this design. The presented design method can be successfully applied to fulfill this objective. The tube shape and adequate tolerance can be attained by using the proposed design method. The mechanical properties of the pipe are evaluated by calculating the Q factor.

Study on Microstructural Characterization, Mechanical Properties and Residual Stress of GTAW Dissimilar Joints of P91 and P22 Steels.

This article deals with the dissimilar joining of two different grade Cr-Mo steel (2.25Cr-1Mo: P22 and modified 9Cr-1Mo: P91) for power plant application. The dissimilar butt-welded joint was produced for conventional V groove design by using the gas tungsten arc welding (GTAW) process with the application of an ERNiCrMo-3 Ni-based super alloy filler. A microstructure characterization was performed to measure the inhomogeneity in the microstructure and element diffusion across the interface in a welded joint. The experiments were also performed to evaluate the mechanical properties of the dissimilar welded joint in as-welded (AW) and post-weld heat treatment (PWHT) conditions. An acceptable level of the mechanical properties was obtained for the AW joint. After PWHT, a significant level of the element diffusion across the interface of the weld metal and P22 steel was observed, resulting in heterogeneity in microstructure near the interface, which was also supported by the hardness variation. Inhomogeneity in mechanical properties (impact strength and hardness) was measured across the weldments for the AW joint and was reduced after the PWHT. The tensile test results indicate an acceptable level of tensile properties for the welded joint in both AW and PWHT conditions and failure was noticed in the weak region of the P22 steel instead of the weld metal.

Multi-condition design optimization of groove flow control technique in an axial-flow pump

Abstract To address the limitations of conventional groove designs in groove flow control technique, this paper optimizes the groove flow control technique for an axial-flow pump combining the design of experiment (DOE), response surface methodology (RSM), and particle swarm optimization (PSO). The sample space is designed using a combination method (OD-LHS) of orthogonal design (OD) and Latin hypercube sampling (LHS). Performance prediction models for the axial-flow pump are established using RSM. Taking the multi-condition comprehensive evaluation function as the final optimization objective, PSO is used to find the optimum groove parameters. The results show that the proposed method is effective in solving multi-condition optimization problems for grooves in axial-flow pumps. The optimal groove length, depth, and distance from the center of the impeller are 0.8, 0.05, and 0.2 times the impeller diameter, respectively, and the number is three times the number of blades. In addition, the optimal grooves effectively improve the hydraulic performance of the axial-flow pump under stall conditions. This study sheds light on the design optimization of the groove flow control technique for axial-flow pumps and other types of hydraulic machinery.

Optimisation of helical geometry of inspection probe for steam generator tubes of the PFBR

The steam generator (SG) tubes of the prototype fast breeder reactor (PFBR) located in Kalpakkam, India, need to be periodically inspected using the remote field eddy current (RFEC) technique. During the pre-service inspection of the SG tubes, it was found that the RFEC probes experienced frequent mechanical breakages. To avoid these failures, changes in the existing structural design of the RFEC probe were required. A helical groove design was proposed to obtain a smooth transition in the variation of stress across the probe during the inspection. It was difficult to calculate the flexural stiffness of the proposed helical geometry probe due to the varying cross-section along its length. In this paper, the smearing approach adopted to calculate the stiffness of the RFEC probe and the sensitivity analysis carried out to determine the optimal design of the probe are discussed. A probe was fabricated based on the helical groove design and tested to qualify its suitability for the SG inspection. The RFEC probe with helical grooves was employed for the pre-service inspection of the SG tubes of the PFBR. More than 200 tubes have been inspected using the proposed design and no mechanical failure of the probe has been observed.

Mechanical design and analysis of a novel variable stiffness actuator with symmetrical pivot adjustment

The safety of human-robot interaction is an essential requirement for designing collaborative robotics. Thus, this paper aims to design a novel variable stiffness actuator (VSA) that can provide safer physical human-robot interaction for collaborative robotics. VSA follows the idea of modular design, mainly including a variable stiffness module and a drive module. The variable stiffness module transmits the motion from the drive module in a roundabout manner, making the modularization of VSA possible. As the key component of the variable stiffness module, a stiffness adjustment mechanism with a symmetrical structure is applied to change the positions of a pair of pivots in two levers linearly and simultaneously, which can eliminate the additional bending moment caused by the asymmetric structure. The design of the double-deck grooves in the lever allows the pivot to move freely in the groove, avoiding the geometric constraint between the parts. Consequently, the VSA stiffness can change from zero to infinity as the pivot moves from one end of the groove to the other. To facilitate building a manipulator in the future, an expandable electrical system with a distributed structure is also proposed. Stiffness calibration and control experiments are performed to evaluate the physical performance of the designed VSA. Experiment results show that the VSA stiffness is close to the theoretical design stiffness. Furthermore, the VSA with a proportional-derivative feedback plus feedforward controller exhibits a fast response for stiffness regulation and a good performance for position tracking.

Optimization of slanted grooved micromixer with a serpentine channel at a lower Reynolds number

Abstract In Lab-On-Chip (LOC) applications, micromixing is the most important step to obtain fast analytical response in many biochemical and biological detections. Design and realization of smaller and shorter mixers with higher efficiency has become a necessity more than a recommendation. In this work, a numerical optimization of a passive mixer with a serpentine-shaped channel is proposed. By considering a laminar flow regime, the continuity and momentum equations, along with the advection-diffusion equation, are solved to evaluate the mixing performance. The optimization of the slanted grooves micromixer with a serpentine channel is achieved using computational fluid dynamics (CFD) and response surface methodology (RSM) based on Box-Behnken design. This method is used to find a second-order polynomial regression model and to obtain the optimal groove design. The considered objective function is the mixing index, while the four design variables are: the number of grooves per half cycle (N), the groove angle (θ), the groove depth to channel height ratio (d/h) and the ratio of groove width to channel width (Wd/W). The optimization results indicate that the highest values of each selected interval of the groove depth to channel height ratio (d/h) and the angle between the radius and the groove (θ), on the other hand, the ratio of groove width to channel width (Wd/W) of about 0.45 are desirable to promote faster mixing. The Flow behaviour in optimized “slanted grooves mixer (SGM) with serpentine channel was tested for low Reynolds number Re ranging between 0.3 and 5, and the results have shown that in the range of Re from 0.3 to 0.7 the mixing index is greater than 85%, for large range of Re from 1 to 4.5, the mixing index reaches the value of 93% in the first cycle of the channel and it approaches 100% for channel length of 1.25 mm from the inlet of the channel. Thus the most important result of this work shows that higher efficiency is obtained for short distance and the required pressure drops decreases. This micromixer can be selected as a good candidate in applications that require a high degree of mixing with relatively small length mixing as polymerase chain reaction (PCR) in the analysis and extraction of DNA.

Friction Stir Welding of 2205 Duplex Stainless Steel: Feasibility of Butt Joint Groove Filling in Comparison to Gas Tungsten Arc Welding.

This work investigates the feasibility of using friction stir welding (FSW) process as a groove filling welding technique to weld duplex stainless steel (DSS) that is extensively used by petroleum service companies and marine industries. For the FSW experiments, three different groove geometries without root gap were designed and machined in a DSS plates 6.5 mm thick. FSW were carried out to produce butt-joints at a constant tool rotation rate of 300 rpm, traverse welding speed of 25 mm/min, and tilt angle of 3o using tungsten carbide (WC) tool. For comparison, the same DSS plates were welded using gas tungsten arc welding (GTAW). The produced joints were evaluated and characterized using radiographic inspection, optical microscopy, and hardness and tensile testing. Electron back scattering diffraction (EBSD) was used to examine the grain structure and phases before and after FSW. The initial results indicate that FSW were used successfully to weld DSS joints with different groove designs with defect-free joints produced using the 60° V-shape groove with a 2 mm root face without root gap. This friction stir welded (FSWed) joint was further investigated and compared with the GTAW joint. The FSWed joint microstructure mainly consists of α and γ with significant grain refining; the GTWA weld contains different austenitic-phase (γ) morphologies such as grain boundary austenite (GBA), intragranular austenite precipitates (IGA), and Widmanstätten austenite (WA) besides the ferrite phase (α) in the weld zone (WZ) due to the used high heat input and 2209 filler rod. The yield strength, ultimate tensile strength, and elongation of the FSWed joint are enhanced over the GTAW weldment by 21%, 41%, and 66% and over the BM by 65%, 33%, and 54%, respectively. EBSD investigation showed a significant grain refining after FSW with grain size average of 1.88 µm for austenite and 2.2 µm for ferrite.

Measurement of pressure distribution and hydrodynamic axial forces of wet clutch discs

Within disengaged wet-running multi-plate clutches a certain drag torque is generated as a result of the differential speed between the discs. These losses can be reduced providing uniform clearances within the clutch pack. To this end, reliable and uniform separation of the discs should be achieved, which can be realized using both mechanical components and hydrodynamic pressure of the oil flow. This paper deals with a method for measuring the hydrodynamic axial force generated by wet clutch discs. This system allows the determination of the correlation between the axial force and the operating parameters of the clutch and the groove design. Using the examples of a radial and a complex grooving, the measurements are validated with 3D CFD simulation results.

Design, fabrication, and characterisation of a silicon microneedle array for transdermal therapeutic delivery using a single step wet etch process

The fabrication of silicon in-plane microneedle arrays from a simple single wet etch step is presented. The characteristic 54.7° sidewall etch angle obtained via KOH etching of (100) orientation silicon wafers has been used to create a novel microneedle design. The KOH simultaneously etches both the front and back sides of the wafer to produce V shaped grooves, that intersect to form a sharp pyramidal six-sided microneedle tip. This method allows fabrication of solid microneedles with different geometries to determine the optimal microneedle length and width for effective penetration and minimally invasive drug delivery. A modified grooved microneedle design can also be used to create a hollow microneedle, via bonding of two grooved microneedles together, creating an enclosed hollow channel. The microneedle arrays developed, effectively penetrate the skin without significant indentation, thereby enabling effective delivery of active ingredients via either a poke and patch application using solid microneedles or direct injection using hollow microneedles. This simple, scalable and cost effective method utilises KOH to etch the silicon wafer in-plane, allowing microneedles with variable length of several mm to be fabricated, as opposed to out-of-plane MNs, which are geometrically restricted to dimensions less than the thickness of the wafer. These microneedle arrays have been used to demonstrate effective delivery of insulin and hyaluronic acid into the skin.

Numerical analysis of vane–slot friction pair in a rolling piston compressor considering deformation and groove design

Rolling piston compressors, which are widely used in refrigeration systems, contain a vane-vane slot friction pair that significantly affects its mechanical efficiency and reliability. In this study, a new simulation model considering the deformation and detailed groove design of the vane-vane slot system is presented. The simulation results show that the vane slot's maximum wear depth increased by approximately 110% after considering the deformation. The optimal design of the vertical groove can reduce friction loss and wear. Compared with the situation without a vertical groove, the optimal vertical groove design can reduce the friction loss of the vane by 17.59%, and manufacturers have begun to adopt this scheme.

Effect of Radial Groove Pad on Copper Chemical Mechanical Polishing

Chemical mechanical polishing (CMP) is a process that reduces step height by making the flat surface when several types of layers are accumulated in a semiconductor device. The three main factors affecting CMP are pad, slurry and conditioner. Among these factors, the pad helps the flow of the slurry and polish the wafer with direct contact. Through changing characteristic of pad that is number of grooves, design of groove, depth and width of pitch, we can control wafer removal rates, with-in wafer non-uniformity and roughness. In this study we added a radial groove (RG) at the circular groove (CG) pad to investigate what effect of the RG to Cu CMP. A study was conducted on how the number of RG affects the slurry flow, how changes in slurry flow affect the pressure distribution between the pad and the wafer, and how this affects CMP. The number of RG was divided into 0, 8, 16, 32, and the actual CMP process and simulation experiment were conducted together. In simulation part, we use computational fluid dynamics (CFD) to compare for slurry transport rates according to the number of RG. Fig. 1 shows the removal rates according to the number of RG, and when the number of RG increases to 32, it shows that removal rates of RG pad is almost 23% higher than CG pad. We consider that these results are related to changes in slurry flow during polishing. This is due to role of RG in quickly replacing the old slurry with the new slurry. Figure 1

Laser Surface Structuring of Commercial Pure Titanium

Aim This Study existent laser surface structuring of commercial pure titanium (Ti) grade II dental implant,surface structuring of the titanium implant expected causing decrease the time of implant healing andaccelerated the periimplant bone formation. So the present study aimed was in vitro evaluation of commercialpure titanium when subjected to two laser surface structuring (dot and groove) in different laser scans andcomparing with titanium surface that not subjected to any surface structuring (control) by using opticalmicroscope, scanning electron microscope (SEM) and X-ray Diffraction analysis (XRD) test.Materials and Methods: CNC fiber laser machine laser was used for performing the structuring on thesurface of the commercial pure titanium (CP Ti) disks and then analyzed with the control group by opticalmicroscope, SEM and XRD test. The study groups are: polished CP Ti (control); (5, 15 and 25) CP Ti withdot design laser scans; (5, 15 and 25) CP Ti with groove design laser scans.Results the optical and SEM results showed a uniform homogenous structure on the surface of the CP Ti forthe two design of all tested laser scans (5, 15 and 25). The XRD results show an increasing in the titaniumoxide layer for the disks with laser structuring comparing to the control one which predicted to increasetitanium osseointegration while maintaining biocompatibility characteristics of the CP Ti.Conclusions: CNC fiber laser machine are successful method for CP Ti surface structuring. For both lasersurfaces structuring design, the 25 laser scan showed more promising results follow by 15 laser scan then 5laser scan and lastly the control group.

Aerodynamics of the newly approved football for the English Premier League 2020\u201321 season

Footballs are typically constructed with 32 panels. Recently, the number of panels has been successively reduced to 14, 8, and 6 panels, and official balls have been adopted with complex panel shapes and aerodynamics that differ from those of 32-panel balls. The official ball for the 2020–21 season of the English Premier League comprises just four panels with a complex panel shape and surface groove design; however, its aerodynamics have not yet been clarified. This study aims to clarify the aerodynamic characteristics (drag, side force, lift force, their deviations, and critical Reynolds number) of the new 4-panel ball (Flight 2020, Nike) in comparison to a 6-panel ball (Tsubasa 2020, Adidas) and conventional 32-panel ball (Pelada 2020, Molten) using a wind tunnel test, surface design measurement, and a simple 2D flight simulation. The results showed that Flight 2020 has greater surface roughness and smaller critical Reynolds number than Pelada 2020 and Tsubasa 2020, resulting to its marginally greater drag force in the supercritical region, and slightly smaller fluctuations of the side and lift forces. Furthermore, Flight with a symmetrical orientation exhibits a significantly higher drag coefficient in the supercritical region, suggesting its greater air resistance during flight under this condition.