Spiral Groove Research Articles

Ultra high-frequency ultrasound of fascicles in the ulnar and radial nerves.

Ultra high-frequency ultrasound (UHFUS) has been demonstrated to allow easy visualization and quantification of median and digital nerve fascicles; however, there is a lack of normative data for other upper limb nerves. The purpose of this study was to use UHFUS to establish normative reference values and ranges for fascicle count and density within selected upper extremity nerves. Twenty-one healthy volunteers underwent sonographic examination of the ulnar, superficial branch of the radial, and radial nerves on one upper limb using UHFUS with a 48 MHz linear transducer. The number of fascicles in each peripheral nerve and fascicle density were assessed. The mean fascicle number and fascicle density for each of the measured nerves was ulnar nerve at the wrist 11.7 and 2.0, ulnar nerve at the elbow 9.2 and 1.1, superficial branch of the radial nerve 7.3 and 2.5, and radial nerve at the spiral groove 4.2 and 0.8. A single significant association was observed between CSA and fascicle number in the ulnar nerve at the wrist (p = .023, r = 0.66). Neither fascicle number nor density could be predicted by age, sex, height, weight, or body mass index. UHFUS may help to establish a baseline of normative data on upper limb nerves that are not frequently biopsied due to their mixed motor and sensory functions and has the potential for increased understanding of nerve fascicular anatomy to improve diagnostic accuracy of focal nerve lesions, particularly those with selective fascicular involvement.

Robotic wire-based friction stir additive manufacturing

High axial force requirement for existing friction stir additive manufacturing technologies is a substantial obstacle to manufacturing of complex reliable components by high-freedom robots. Here, we proposed a new robotic wire-based friction stir additive manufacturing (R-WFSAM) method, characterized by paraxial feeding wires and pre-plasticization process, to enable the formation of deposited layers with significantly low force. The spiral groove design on the screw tool facilitates the pre-plasticization of materials prior to deposition and the continuous extrusion of the material, reducing axial force and diminishing the reliance on high-stiffness equipment for solid-state relevant technologies. Fully dense aluminum alloy components on the 2D plane and 3D curved surface by hybrid position/force control were successfully manufactured. The sufficient material flow and material mixing behavior during deposition on the plane induced by the multi-pin design strengthened the interfacial bonding. Homogeneous and fine grains were also achieved due to severe plastic deformation. The R-WFSAM Al-Si alloy component possessed an ultimate tensile strength of 230±5 MPa and an uniform elongation of 28.1±1.0 %, exhibiting excellent isotropic mechanical properties. This method provides a novel approach for manufacturing large-size complex structural components with high flexibility and field re-manufacturing.

Carbide Twist Drill Spiral Groove Abrasive Flow Polishing and Abrasive Flow Analysis

Carbide Twist Drill Spiral Groove Abrasive Flow Polishing and Abrasive Flow Analysis

Multi‐Material Digital Light Processing (DLP) Bioprinting of Heterogeneous Hydrogel Constructs with Perfusable Networks

AbstractThe challenges of replicating the complex mechanical and structural diversity of natural tissues in vitro by leveraging multi‐material digital light processing (DLP) bioprinting are addressed. This technique utilizes PEGDA‐AAm bio‐ink to develop multi‐component, cell‐laden hydrogel constructs with varying moduli. These constructs not only possess heterogeneous mechanical properties but also feature complex architectures and precisely engineered surface microstructures. The hydrogel microfluidic chips are successfully fabricated with perfusable microchannels, embedding various cell types within the matrix. This approach enables the bioprinting of intricate cell‐laden structures with unique surface topologies, such as spiral grooves and triply periodic minimal surfaces (TPMS), which effectively influence cell alignment, spreading, and migration. By integrating various cell‐laden PA hydrogels, the diverse mechanical moduli of biological tissues, including bone, liver lobules, and vascular networks are replicated. This technique ensures high‐fidelity differentiation between cell types and regions. These findings provide valuable insights into the impact of substrate modulus and structure on cell behavior, underscoring the potential of multi‐component, multi‐modulus hydrogel constructs in creating sophisticated structures with custom‐tailored mechanical properties. This study significantly advances the field by demonstrating the feasibility and effectiveness of multi‐material DLP bioprinting in developing complex, functionally relevant tissue models for tissue engineering and regenerative medicine.

Control and analysis of floating ability of aeronautical cylindrical spiral groove gas seal based on F-K model

The slip flow phenomenon caused by the gas floating seal in ultra-thin gas films and high-altitude rarefied gas environments occurs frequently. This study represents the first attempt to calculate the gas film floating force by considering the coupling relationship among the slip flow effect, the surface micro-grooves, and the eccentricity using a high-precision eight-node finite difference method based on the linearized Boltzmann equation for a spiral-grooved cylindrical gas seal. Furthermore, the influence of slip flow on the operational and groove parameters of the spiral-grooved cylindrical gas seal is investigated and discussed. Results show that the velocity gradient of the lubrication gas is reduced and the effect of the fluid hydrodynamic pressure is weakened because of slip flow, particularly in high-speed, low-pressure, and high-eccentricity fields. However, increases in groove depth, number, and length improve the gas film floating force, which strengthens the slip flow response in the grooves. Therefore, the slip flow reduces the gas film floating force, but when the groove depth exceeds 32 μm and the groove length is greater than 45 mm, the slip flow may become negligible. The results presented here provide a theoretical basis to broaden the application scope of dynamic seals in the aerospace field.

Effect of two-phase flow lubrication on sealing performance of spiral groove mechanical seal under high speed and low temperature conditions

The function of the turbo-pump shaft within the liquid rocket engine is rendered exceedingly complex due to the operation in an environment characterized by drastically low temperatures, elevated velocities, and high pressures. Given these operational conditions, it is highly plausible that a two-phase flow might form within the liquid film located on the terminal face of the mechanical seal. This liquid-vapor mixture significantly modifies the fluid lubrication pattern across the end faces and poses consequential implications on the overall sealing stability. In this study, the phase change characteristics of the fluid in the seal clearance were investigated based on the Laminar and Mixture multi-phase flow models in a spiral groove mechanical seal. The behaviors of two-phase flow characteristics and phase transition under extreme temperature, rotational speed and pressure with liquid nitrogen media were studied. The sealing performance was quantified through metrics including the leakage rate, opening force, and internal gas phase volume ratio. The findings offered valuable insights into the role of operational conditions in influencing the phase change of the liquid film. Moreover, we discerned and explicated the intricate interconnections between the leakage rate, the opening force, and the phase change behavior of the liquid film.

Ssessment of cutting fluids supplying method influence on contact processes when drilling stainless steel 12Х18Н10Т

The authors have considered the process of blind holes processing during drilling operations when processing stainless steel 12Х18Н10Т. Spiral drills made of high-speed steel were used as cutting tools. There are some typical problems in this process such as difficulty of removing chips and cutting fluids supply to the machining zone. One more problem is that while removing chips along spiral grooves, they rub against the surface of the hole and thus become deformed, which results in the deterioration of surface quality. Therefore, a comparative assessment of various coolants influence was carried out depending on the method of their supply under closed cutting conditions.

Evolution mechanism and parametric investigation of relative negative pressure zone in spiral groove gas face seal for aero-engine at high rotational speed

As an advanced sealing technology, spiral groove gas face seal has excellent sealing performance. However, it is rarely used in aero-engine. Previous investigation proposed that the relative negative pressure zone (RNPZ) in the spiral groove gas face seal can regulate the sealing performance. In this paper, further numerical simulation work is carried out. By quantifying the obstruction effect, viscous pumping effect and shear effect, the evolution mechanism of RNPZ under different film thicknesses and groove depths is revealed. Then, the parametric analysis of spiral groove configuration and groove number is carried out. Through the sub-regional quantitative analysis of the groove, the influence mechanism of structural configuration on RNPZ is revealed. Finally, combined with the hydrodynamic performance analysis, the spiral groove seal structure under optimal conditions is obtained. It is found that under the condition of high speed and low inlet pressure of aero-engine, RNPZ is suppressed by adjusting the structure of the spiral groove to enhance the shear effect, the pumping effect at the top of the groove and reduce the pumping effect at the bottom of the groove. When the number of grooves is 20 and the groove depth is 3 μm, the stiffness-leakage ratio of structure B and C can be increased by 10.15 % and 12.68 %, and the sealing performance is the strongest. This work can provide a theoretical and data basis for the subsequent optimization design of aero-engine gas face seals.

Design and Analysis of a Novel Variable Stiffness Joint Based on Leaf Springs

In response to challenges like the complexity and limited scalability of existing variable stiffness joints, a novel variable stiffness joint, based on leaf spring elements, is introduced in this paper. The joint stiffness can be adjusted in real time by changing the effective length of the leaf spring via the use of an Archimedean spiral groove. The stiffness adjustment range and load capacity of the joint can be defined by manually configuring the number of springs involved during offline joint operations. A stiffness model for the joint is established based on the cantilever beam theory of material mechanics. The coupled effects of the design parameters of the variable stiffness mechanism on joint stiffness, elastic torque, and stiffness adjustment resistance torque are analyzed. A dynamic model for the joint is developed, while a PID controller is designed for simulation purposes. The motion characteristics of the joint are analyzed, confirming that this approach has certain advantages in terms of stiffness adjustment speed and accuracy.

Vaporization Phase Transition in Cryogenic Liquid Oxygen Sealing Film on Spiral Groove Faces.

The property of vaporization phase transition in liquid oxygen face seals is a key factor affecting the stability of mechanical face seals in many fields, especially under cryogenic conditions. Here, a numerical model based on the saturated vapor pressure is established to investigate the vaporization phase transition property of liquid oxygen sealing film. The novelty of this model is to take the influence of heat transfer and face distortions into consideration at the same time. The pressure and temperature distributions as well as face distortions are calculated, and then the property of vaporization phase transition and sealing performance are analyzed. It is found that spiral grooves may lead to the complex film temperature distributions and irregular vaporization distributions. With the increase in seal temperature and decrease in seal pressure, the vaporization area extends from the low-pressure side to the grooves area, and the vaporization rate increases rapidly. The more important thing is that the vaporization often brings a drastic fluctuation and non-monotonic change in opening force. Specifically, with the increase inin seal temperature from 55 K to 140 K, the opening force fluctuates violently, and the fluctuation range is more than 50%, showing an obvious instability. Finally, this study provides a design range of pressure and temperature values for liquid oxygen face seals. In these ranges, this kind of face seals can have a stable operation, which is beneficial to the practice engineering related to the complex properties of sealing fluid.

Reflective vortex focusing for acoustic contact-free object rotation

The use of acoustic vortex waves with angular momentum is a promising means of transferring mechanical torque to an object without making any physical contact. However, the existing passive-conversion vortex lenses are unable to produce strong acoustic radiation torque. To address this issue, we propose a flat reflector sculpted by spiral grooves. It reflects and converts incident waves into vortex-focusing waves that generate radiation torque. Compared with a transmission-type lens, a reflection-type vortex focusing plate exhibits superior functionality in converging sound waves and creating a stronger circular intensity flow. In this work, we analyze the vortex-focusing sound by Rayleigh-Sommerfeld integral theory and boundary element simulation, confirmed by experiments. The number, depth and direction of spiral grooves determine the topological charge, focusing intensity and torque direction, respectively. We evaluate the local and total acoustic radiation forces and torques, acting on small and large fixed spherical targets in the vortex-focusing beam. As a result, spinning a centimeter-size origami pinwheel several times larger than the wavelength at 40 kHz is realized without direct contact, by utilizing the enhanced acoustic radiation torque converged by the reflector. This technology enables efficient convergence of acoustic waves and simultaneous contactless transfer of mechanical torque to an object, thereby presenting potential applications in sound energy harvesting and wireless power supplies.

Prediction of spiral groove dry gas seal performance and intelligent optimization of structural parameters

Using gas lubrication theory and finite difference methods, this study solve the gas film pressure equation in spiral groove dry gas seal and assesses key performance aspects like opening force, leakage rate, and gas film stiffness. It examines how structural parameters affect sealing performance and utilizes Latin hypercube sampling with a radial basis neural network, optimized by genetic algorithms, for predictive analysis. The effectiveness of control variable, orthogonal, and genetic algorithm methods in optimizing sealing performance is comparatively analyzed. Findings reveal a substantial impact of structural parameters on sealing performance with intricate interdependencies. The neural network, trained with 400 samples, achieves a prediction error below 3.6%. Genetic algorithm optimization of structural parameters notably enhances seal performance over other methods.

Optimal design and experimental research on the spiral groove wheel fertilizer apparatus

As the "core" of fertilizer machinery, the fertilizer apparatus has a significant impact on the effect of fertilization operation. At present, the straight-grooves type external groove wheel fertilizer apparatus is widely used, which has the problem that the fertilizer flow fluctuates periodically and is not conducive to precision fertilization. Therefore a kind of the spiral groove wheel fertilizer apparatus is proposed in the paper, and the designed fertilizer apparatus is experimented and optimized by using Design-Expert Software 10 and a self-made fertilizer experiment bench. Taking the fertilization amount and the variation coefficient of fertilization amount as the experiment index, the interaction effects of the groove radius, spiral rising angle, groove wheel rotation speed, and fertilizer tongue inclination of the spiral groove wheel type fertilizer wheel on the fertilization performance are analyzed. The quadratic regression models of multiple factors of the fertilization amount and the variation coefficient of fertilization amount are established. Through optimization and experiment validation, the optimal combination of parameters is determined as follows: the groove radius is 13.5 mm, the spiral rising angle is 62°, the groove wheel rotation speed is 29.4 r/min, the fertilizer tongue inclination is 5°, the fertilization amount is 17.810 g and the variation coefficient of fertilization amount is 5.60%.

Влияние геометрии инструмента на формирование сварного соединения при сварке трением с перемешиванием алюминиевого сплава АМг5

One of the important parameters influencing the formation of a weld during friction stir welding is the tool geometry, which affects the processes of heat generation and stirring of metals in their connection zone. These processes influence the formation of a high quality and strength welded joint without continuity defects. In this regard, it is relevant to analyze the influence of tool geometry on the welding mode parameters, at which the welded joint is formed without continuity defects, as well as on the welded joint strength under static tension. The work considers the influence of the cylindrical and conical shapes of the tool pin, as well as the conical shape of the pin with a thread on its outer surface and a spiral groove on the end surface of the tool shoulder on the welding mode parameters, at which the welded joint is formed without continuity defects. The study shows that changing the shape of the pin working surface from cylindrical to a conical one had no effect on the range of welding mode parameters, at which the welded joint is formed without continuity defects. It has been found that the presence of a thread on the pin outer surface and a groove on the end surface of a tool shoulder allows producing welded joints without continuity defects in a wider range of welding mode parameters compared to a simpler tool geometry. The macrostructure of the resulting welded joints was considered. It has been found that the studied tool geometry has almost no influence on the maximum strength values of welded joints produced by friction stir welding and reaches 95 % of the strength of the base metal.

Spiral groove bearing design for improving plasma skimming in rotary blood pumps

High-efficiency plasma skimming is hopeful to prevent hemolysis inside spiral groove bearings (SGBs) because it can exclude red blood cells from the ridge gap with a high shear force. However, no study reveals the shape design of SGBs to improve plasma skimming. Therefore, this study proposed and applied a groove design strategy to designing an optimal SGB for enhancing plasma skimming in a rotary blood pump (RBP). Initially, we proposed the design strategy that the shape of the groove for enhancing plasma skimming corresponds to the direction of blood flow in the ridge gap. Second, we visualized the cell flow in a specially designed experimental RBP to determine the direction of blood flow, which was helpful in the subsequent SGB design. Then, we created an SGB to provide superior plasma skimming and applied it to the experimental RBP. We evaluated the plasma skimming effect of SGB at rotational speeds ranging from 2400 to 3000 rpm and hematocrit conditions between 1% and 40%. At a 1% hematocrit, the plasma skimming efficiency for the entire SGB was greater than 95%. In all hematocrit conditions, the efficiency at the inner ridges of the SGB was greater than 80%. The results showed the designed SGB successfully induced excellent plasma skimming within ridge gaps. This study is the first to propose and apply a shape design strategy to generate excellent plasma skimming within an SGB. This study may contribute to the prevention of SGB hemolysis inside SGB for use in RBPs.

Dissimilar friction-stir welding of aluminum alloys 2519, 6061, and 7050 using an additively-manufactured tool

This work was undertaken to evaluate the feasibility of the additively-manufactured tool for dissimilar friction-stir welding (FSW) of 2519, 6061, and 7050 heat-treatable aluminum alloys. The tool design included a flat shoulder with an Archimedean spiral groove and a threaded probe with a Triflute profile. It was found that the application of such a tool provided a nearly twofold decrease in Z-force and essentially enhanced the mechanical mixing of dissimilar materials within the stir zone. Nevertheless, despite the enhancement effect, FSW was inefficient for a homogeneous intermixing of dissimilar materials, and a distinct interface boundary was present within the stir zone. It was also found that the mechanical performance of the welded joints was sensitive to the initial temper condition of the welded alloys. Specifically, FSW of the alloys in the solution-annealed condition provided no significant influence on material strength, while that in the precipitation-hardened state led to significant material softening. During the post-weld T6 treatment, extensive nucleation of silicon-rich particles was found to occur at this interface. It was deduced that those promoted cracking during transverse tensile tests, thus giving rise to the decohesion of the dissimilar welds along the interface boundary. Hence, the post-weld T6 treatment was concluded to be unfeasible for dissimilar aluminum welds.

Reference Values of Nerve Cross-sectional Area Obtained by Ultrasound in the Upper Extremity Correlated with Electrodiagnosis in Thai Adults

OBJECTIVE To evaluate the ultrasonography cross-sectional area (CSA) reference values of nerves in the upper extremity correlated with electrodiagnosis in healthy Thai adults. METHODS A cross-sectional study was performed. Ninety participants were recruited and their CSA at 10 sites on the median, ulnar, and radial nerves were measured bilaterally. A nerve conduction study (NCS) was conducted and the correlations between the nerve CSA and age, sex, height, weight, body mass index (BMI), and NCS parameters were studied. RESULTS The mean CSA ranged from 5.8±1.4 to 9.5±1.5 mm2 along the median nerve and 4.5±0.8 to 7.7±1.7 mm2 along the ulnar nerve. The mean CSAs of the radial nerve at the elbow and spiral groove were 5.0±0.9 and 4.6±0.8 mm2, respectively. The CSA of the median nerve at the wrist and the CSA of the radial nerve at the spiral groove were positively correlated with weight and BMI, whereas the CSA of the median nerve at the elbow was positively correlated only with weight. There was an association between CSA values and electrodiagnosis parameters as the nerve CSA increased, as the latency was prolonged, and as the amplitude decreased. CONCLUSIONS The reference values of nerve CSA in the upper extremity at multiple sites can be helpful in the evaluation of peripheral nerve disorders in the Thai population. KEYWORDS cross-sectional area, ultrasonography, peripheral nerves, electrodiagnosis

Theoretical study on the pressure expansion mechanism of diffused self-pumping hydrodynamic mechanical seal

The pressure expansion performance is the key and basis for the diffused self-pumping hydrodynamic mechanical seal to achieve its good cooling performance, self-cleaning performance, and sealing performance. Using the moment of momentum theorem and Stodola's formula, the pressurization effect of the spiral groove on the fluid was analyzed, and the energy head equation of the work done by the spiral groove on the fluid is established. According to the principle of conservation of energy, the energy equation and Bernoulli equation of the work done by the spiral groove on the fluid are derived, the mathematical expression of the conversion of fluid kinetic energy into hydrostatic pressure in the diffuser groove was established, the energy change and energy distribution problems of the fluid after the work of the spiral groove are clarified, and the pressure expansion mechanism is revealed. Through numerical simulation, the relationship between the fluid pressure at the sealing interface, the position and size of the high-pressure field, the opening force, and the leakage rate under different rotational speeds and the structural parameters of the diffuser groove were explored. Finally, the pressure expansion performance of the ordinary self-pumping hydrodynamic mechanical seal and diffused self-pumping hydrodynamic mechanical seal is compared. The results show that the diffuser groove can effectively convert part of the fluid kinetic energy into pressure energy, improve the opening force of the sealing interface, and have a good pressurization effect on the sealing end face. With the widening of the diffuser groove, the pressure peak of the sealing interface increases, the high-pressure field area continues to expand and tends to expand toward the outer diameter of the seal ring, and the opening force also increases significantly; increasing the depth of the diffuser groove will cause the pressure peak of the sealing interface to become smaller, and the area of the high-pressure field will also decrease rapidly, which is not conducive to improving the opening force of the sealing end face.

Calculation of the Operational Characteristics of the Impulse Gas-Barrier Face Seal

Abstract The problem of reducing leaks along the pump or compressor shaft of pumped liquids and gases into the environment is very urgent. Serious difficulties have to be faced when sealing the shafts of machines that pump aggressive, toxic, explosive and fire-hazardous environments. According to modern occupational safety requirements, such pumps and compressors should use double seals with a barrier medium whose pressure exceeds the sealed one by 0.05-0.2 MPa. Currently, liquid-lubricated double mechanical seals are widely used in chemical production equipment, however, over the last decade of the 20th century, leading companies have developed a number of designs of double gas mechanical seals for pumps and chemical production devices, which significantly exceed liquid-lubricated seals in their performance characteristics. The vast majority of these seals use a gas-dynamic principle of operation, i.e. spiral, logarithmic, T-shaped or other micro grooves are made on the sealing faces of their rings, which, when rotated, create an additional gas dynamic force that ensures the functioning of these seals with a micron gap between the sealing pair. In this paper, the design, principle of operation and engineering methodology for calculating the main characteristics of a impulse gas barrier face seal, in which one pair of sealing rings performs the functions of a double mechanical seal, is considered. The design is simple, compact and, thanks to the more advanced principle of creating a gap between the sealing pair, is able to maintain operability in a wide range of sealing and barrier pressures. The existing experience of operating seals of this type on chemical production pumps has confirmed their high efficiency, reliability and safety.

Anterior transposition of the radial nerve to achieve primary suture for its reconstruction: Anatomical feasibility study

IntroductionRadial nerve palsy after humeral shaft fractures is often associated with formation of a neuroma in continuity. The current standard of treatment is neuroma resection and nerve grafting with contentious results. Anterior transposition of the radial nerve may reduce the length of its path, allowing reconstruction by primary suture. The aim of this study was to determine the maximum length of radial nerve defect that can be treated by the anterior transposition to allow primary suture to be performed. MethodsWe use 10 arms from five fresh cadavers. The radial nerve was dissected in the lateral inter-muscular septum and along the anterior aspect of the forearm. The radial nerve was transected at the level of the spiral groove and both stumps were than transposed anterior to the medial inter-muscular septum. The length of tension-free overlap that could be achieved was measured. ResultsThe average length of the overlap at zero degrees of elbow flexion was 10.00 ± 1.84 mm. Theoretically, this will allow a defect of 20 ± 3.69 mm SD to be treated by primary suture. ConclusionOur results suggest that anterior transposition can be used for radial nerve defects up to 2 cm; however, dissection of both stumps proved to be challenging.