Slender Shaft Research Articles

On the Neotropical Brincadorus: redescription, new species, taxonomic key and description of a related new genus (Insecta: Hemiptera: Cicadellidae: Deltocephalinae)

The Neotropical genus Brincadorus Oman, 1938 is redescribed, and five new species are described and illustrated. Brincadorus cruceno sp. nov., from Bolivia and Peru, can be differentiated by the long and slender aedeagus, with a pre-apical dorsal spine and apex curved downwards. Brincadorus gracilis sp. nov., from Ecuador and Peru, can be distinguished by the slender subgenital plates, aedeagus with slender shaft and basidorsal processes without a preapical tooth. Brincadorus limoncocha sp. nov. from Ecuador, can be differentiated by the robust aedeagus shaft, and bifurcate basidorsal processes. Brincadorus quincemil sp. nov., from Peru, can be distinguished by the bifurcate apex of the subgenital plates, and aedeagus basidorsal process with a preapical dorsal tooth. Brincadorus yanayacu sp. nov., from Ecuador, can be distinguished by the thorn-like apex of the subgenital plates, and short aedeagus, without processes. A key to species is provided, and a female is illustrated and described for the first time. New records for Ecuador and Peru are provided. A new genus that shares similarities with Brincadorus is described. Saltadorus gen. nov. can be distinguished by the smaller size, male pygofer with a pair of long inner lateral processes arising sub-basally on the dorsal region and extending beyond the pygofer apex, widely separated and elongated subgenital plates, and robust aedeagus with a conspicuous sclerotized gonoduct protruding from the atrium. Saltadorus blahniki sp. nov., from Peru, can be identified by the elongated male pygofer, and aedeagus without processes. Saltadorus dietrichi sp. nov., from Peru, can be distinguished by the shorter male pygofer, and aedeagus with a pair of subapical dorsal teeth. Based on the results of recent phylogenomic analyses, Brincadorus is removed from Bahitini and, along with Saltadorus, is considered unplaced to tribe in Deltocephalinae, pending further study.

Genetic algorithm-based error correction algorithm for CNC turning machining of mechanical parts

This paper discusses how to improve the machining precision in the turning of slender shaft. The main cause of dimensional error in slender shaft machining is analyzed by establishing dimensional error model and using genetic algorithm to optimize cutting parameter selection. Based on this, the proportional-integral-differential control error compensation is proposed to reduce the error in the turning process of slender shaft. Through the simulation experiment, the machining size error of slender shaft under different cutting parameters is obtained. It is found that the increase of back blowing and feed rate will aggravate the dimensional error, while the increase of CS will reduce the dimensional error. The error after the proportional-integral-differential control error compensation is much smaller than that without the error compensation. The experimental results show that the method is reliable in reducing the errors in the turning of slender shaft, and can realize the machining mode with higher precision and efficiency. This is of great significance to the development of machinery manufacturing industry.

Dynamic Behavior of Helical Piles in Dry and Liquefiable Soils using Scaled Shake Table Tests

The dynamic behavior of helical piles with different numbers of helices as well as a single slender shaft was examined through a series of scaled shake table tests. Multiple shakings were applied during each test series to evaluate the seismic behavior of the helical piles and the slender shaft considering different response parameters. A considerable ground settlement was observed during the first shaking in each test series, whereas negligible helical pile and slender shaft settlements were measured during all tests. The dynamic response of the helical piles was evaluated based on their bending moment variation along the depth and various measured response parameters at the model superstructure level. The bending moment variation indicated a similar trend along the depth for the helical piles and the slender shaft: the maximum moment was consistently observed at the boundary between dense and liquefiable layers. The observed bending moments along the depth increased with increases in input motion amplitude and superstructure weight. Densification of the liquefiable layer during different test series reduced the maximum bending moment along the depth for each pile due to increased relative density. Increasing the number of helices enhanced the dynamic performance of the helical piles compared to the slender shaft in terms of maximum bending moment, maximum horizontal displacement, residual horizontal displacement, and superstructure acceleration in different ground conditions.

Machine Learning Techniques for Multi-Fault Analysis and Detection on a Rotating Test Rig Using Vibration Signal

Machine health monitoring of rotating mechanical systems is an important task in manufacturing engineering. In this paper, a system for analyzing and detecting mounting defects on a rotating test rig is developed. The test rig comprises a slender shaft with a central disc, supported symmetrically by oscillating ball bearings. The shaft is driven at constant speed (with tiny variations) through a timing belt. Faults, such as the translation of the central disc along the shaft, the disc eccentricity, and defects on the motor reducer position or timing belt mounting position, are imposed. Time and frequency domain features, extracted from the vibration signal, are used as predictors in fault detection. This task is modeled as a multi-class classification problem, where the classes correspond to eight health states: one healthy and seven faulty. Data analysis, using unsupervised and supervised algorithms, provides significant insights (relevance of features, correlation between features, classification difficulties, data visualization) into the initial dataset, a balanced one. The experiments are performed using classifiers from MATLAB and six feature sets. Quadratic SVM achieves the best performance: 99.18% accuracy for the set of all 41 features extracted from X and Y accelerometer axes, and 98.93% accuracy for the subset of the 18 most relevant features.

Crossing Total Occlusions Using a Hydraulic Pressure Wave: Development of the Wave Catheter.

With the ongoing miniaturization of surgical instruments, the ability to apply large forces on tissues for resection becomes challenging and the risk of buckling becomes more real. In an effort to allow for high force application in slender instruments, in this study, we have investigated using a hydraulic pressure wave (COMSOL model) and developed an innovative 5F cardiac catheter (L = 1,000 mm) that allows for applying high forces up to 9.0 ± 0.2 N on target tissues without buckling. The catheter uses high-speed pressure waves to transfer high-force impulses through a slender flexible shaft consisted of a flat wire coil, a double braid, and a nylon outer coating. The handle allows for single-handed operation of the catheter with easy adjusting of the input impulse characteristic, including frequency (1–10 Hz), time and number of strokes using a solenoid actuator, and easy connection of an off-the-shelf inflator for catheter filling. In a proof-of-principle experiment, we illustrated that the Wave catheter was able to penetrate a phantom model of a coronary Chronic Total Occlusion (CTO) manufactured out of hydroxyapatite and gelatin. It was found that the time until puncture decreased from 80 ± 5.4 s to 7.8 ± 0.4 s, for a stroke frequency of 1–10 Hz, respectively. The number of strikes until puncture was approximately constant at 80 ± 5.4, 76.7 ± 2.6, and 77.7 ± 3.9 for the different stroke frequencies. With the development of the Wave catheter, first steps have been made toward high force application through slender shafts.

All-round responses and boundaries of a shaft and dry friction damper assembly

A helicopter tailrotor driveline is equipped with dampers to suppress the resonance of transmission shafts. A dry friction damper and a slender shaft form an assembly The comprehensive understanding of different responses of the assembly provides the basis for a more reasonable parameter configuration of the damper. To this end, the assembly is modeled as a dynamic system with rub impact between a rotor with continuous parameter distribution and a suspended elastic stator. Boundaries of rub impact and condition of Hopf bifurcation are derived. Pinned natural frequencies and backward whirl frequencies are solved by analytical deduction. The critical speed for triggering a backward whirl with consideration of eccentric excitation is obtained by the multiple scale perturbation method. Then, all-round responses and boundaries are solved by both analytical and numerical approaches based on the parameters of a helicopter. The effects of friction coefficient, internal damping, suspension stiffness, variable impact stiffness, etc. on the boundaries are presented in detail with the discussion of relationships between physical reasons and analytical conditions. Results show that smaller impact stiffness difference and friction coefficient, a greater mass damping ring, moderate suspension stiffness, greater internal and external damping are the key factors for the damper design. This study has reference significance not only for the assembly in a helicopter but also for similar mechanical systems.

Design and modeling of a novel DNA-inspired helix-based continuum mechanism (DHCM)

Helix-based structures have been popularly used in flexible surgical tool designs due to their large bending range. However, the helix structures also have low compressional and torsional stiffness, which results in a limited payload. In this paper, we addressed these limitations by presenting a novel helix-based structure that mimicks the DNA double helix structure. This DNA-inspired helical continuum manipulator (DHCM) contains a helix structure and a constraint structure (a slender shaft or reinforced rings) that mimicks the base pairs of the DNA structure. Simulation results revealed that the stiffness of the helix structure is improved with the constraints. At the same bending stiffness, compared to the simple helix structure, the compressional and torsional stiffness of DHCM with the shaft constraint were improved by 12.3 times and 3.2 times, respectively. The kinematics of the DHCM were derived to predicate the deformation of the DHCM based on the piecewise constant curvature assumption. The model predicted deformation of the DHCM with a mean error of 4.16 mm (6.9%). The equivalent stiffness model of the DHCM was proposed and used to derive the statics of the DHCM. The mean error of distal end between statics predictions and experiment results was 1.01 mm (1.7%).

Dynamic analysis and stability prediction of nonlinear feed system coupled with flexible workpiece

The workpiece is prone to self-excited vibration when turning a slender shaft and the flexibility cannot be ignored in this condition. In this paper, a new flexible tool-workpiece system is developed to investigate the nonlinear dynamics and chatter stability for in a turning process. The piecewise-nonlinear restoring function of the tool system is derived by calculating axial deformations and forces of the ball screw feed system. With the variation of time delay, the dynamic behaviors of the cutting system are analyzed by numerical method, which manifests as periodic, quasi-periodic, and chaotic motions. Through determining the critical chip width under different spindle speed, the stability lobe diagram (SLD) of nonlinear system is obtained to distinguish stable and unstable states. In addition, the dynamic characteristics and SLD of nonlinear system are compared with linear system. An experiment is carried out to observe the vibration phenomenon under stable and unstable turning conditions and verify the accuracy of stability prediction.

Homo naledi pollical metacarpal shaft morphology is distinctive and intermediate between that of australopiths and other members of the genus Homo

Homo naledi fossils from the Rising Star cave system provide important insights into the diversity of hand morphology within the genus Homo. Notably, the pollical (thumb) metacarpal (Mc1) displays an unusual suite of characteristics including a median longitudinal crest, a narrow proximal base, and broad flaring intrinsic muscle flanges. The present study evaluates the affinities of H. naledi Mc1 morphology via 3D geometric morphometric analysis of shaft shape using a broader comparative sample (n = 337) of fossil hominins, recent humans, apes, and cercopithecoid monkeys than in prior work. Results confirm that the H. naledi Mc1 is distinctive from most other hominins in being narrow at the proximal end but surmounted by flaring muscle flanges distally. Only StW 418 (Australopithecus cf. africanus) is similar in these aspects of shape. The gracile proximal shaft is most similar to cercopithecoids, Pan, Pongo, Australopithecus afarensis, and Australopithecus sediba, suggesting that H. naledi retains the condition primitive for the genus Homo. In contrast, Neandertal Mc1s are characterized by wide proximal bases and shafts, pinched midshafts, and broad distal flanges, while those of recent humans generally have straight shafts, less robust muscle flanges, and wide proximal shafts/bases. Although uncertainties remain regarding character polarity, the morphology of the H. naledi thumb might be interpreted as a retained intermediate state in a transformation series between the overall gracility of the shaft and the robust shafts of later hominins. Such a model suggests that the addition of broad medial and lateral muscle flanges to a primitively slender shaft was the first modification in transforming the Mc1 into the overall more robust structure exhibited by other Homo taxa including Neandertals and recent Homo sapiens in whose shared lineage the bases and proximal shafts became expanded, possibly as an adaptation to the repeated recruitment of powerful intrinsic pollical muscles.

Reliability Sensitivity Analysis of Turning Error for Slender Shaft

Reliability Sensitivity Analysis of Turning Error for Slender Shaft

Hybrid composite shaft of High-Speed Rotor-Bearing System - A rotor dynamics preview

In this present study, the detailed rotor dynamic evaluation of hybrid composite material rotating shaft of a power turbine high-speed rotor-bearing system is presented. The slender power turbine shaft of front driving turboshaft engine powering the rotorcraft requires a stiffer and lighter material to exhibit better rotor dynamics. Based on the preliminary investigation which predicted substantial rotor dynamic advantages, the laminated composite material shaft is proposed in the compressor section of the rotor-bearing system. To avoid the direct exposure of composite material to the harsh environment of gas turbine engine, hybrid metal fiber form of rotating shaft is employed. The hybrid metal fiber shaft is comprised of a core laminated carbon-epoxy tube sandwiched by steel tubes both inside and outside. The effect of parametric variation in the laminate and length of the hybrid shaft is evaluated and compared with the existing steel shaft. The viscoelastic material damping of carbon-epoxy laminate is also included as a rotating internal damping to evaluate the rotor dynamic instability threshold of the rotor-bearing system. From the analysis, it is found that the combination of metal and fiber-reinforced material can effectively leverage the combined strengths of both materials.

Measuring straightness errors of slender shafts based on coded references and geometric constraints

The coded references and geometric constraints based method is suggested to solve the inconsistency problem of measurement range and accuracy for slender shafts. First, a slender shaft is divided into segments. Images of each segment along with a coded and calibrated reference are taken at two object distances. The code of the reference is obtained using the template match technique. Consequently, the coordinates of the feature points of the reference are solved. Thus, the external parameters of the camera are calculated. A mathematical model of the diameter, centre coordinate and external parameters is established based on the pinhole imaging principle. The problem that only one image cannot extract the centre coordinate is solved, as is the pseudo-diameter problem. A coordinate transformation model for these feature points is established and the sectional measurement results are associated by using the model. Experiments are carried out on lead screws; the measuring uncertainty of the experimental system is 0.007 mm, which is 12.9% higher than that of a coordinate measuring machine. The systematic error of the experimental system is 0.01754 mm. It is proved that the suggested method can stably and reliably measure the straightness errors of slender shafts with high accuracy.

Analysis of Turning Process of Slim Shaft Based on Finite Element Method

Based on the analysis of turning bending deformation of the ordinary turning (forward) machining method of the slender shaft, a reverse turning machining method of the slender shaft is proposed, the bending deformation analysis of the reverse turning of the slender shaft is performed, the finite element method is used. The machining accuracy of the two turning solutions is simulated respectively. Finally, it is verified through experiments that reverse turning can improve the turning accuracy of slender shaft parts to a certain extent.

Nonlinear Vibration Prediction of a Highly Flexible Rotor Supported by an Axial Groove Journal Bearing Considering Journal Angular Whirling Motion

Abstract The difference in dynamic behavior of the rotor-bearing system supported by the bearing model that considers both lateral and angular whirling motions of the journal (model A), and the model that considers only lateral whirling motion (model B) is investigated. The rotor model consists of a slender shaft, a large disk, and two small disks supported by a self-aligning rolling element bearing (REB) and an axial groove journal bearing (JB) of length-to-diameter ratio (L/D) = 0.6. Three positions of the large disk: 410, 560, and 650 mm measured from the REB, are investigated. Numerical integration of the rotor-bearing system which is modally reduced to the first forward (FWD) mode is performed at above the onset speed of instability until either a steady-state journal orbit or contact between the journal and the bearing occurs to identify the bifurcation type. Numerical results using model A indicate subcritical bifurcation with the contact between the journal and the inboard (IB) side of the bearing in all three large disk positions, whereas those of model B indicate subcritical bifurcation when the large disk position is at 410 mm, and supercritical bifurcation is observed in the other two cases. Finally, the experiments at the same three large disk positions are performed. Subcritical bifurcation with the contact between the journal and the IB side of the bearing is observed in all large disk positions, which conforms with the calculation result of model A. Hence, model A is essential in nonlinear vibration analysis of a highly flexible rotor system.

Numerical analysis of gasification characteristics in combined coal gasification and flash ironmaking process

The combined coal gasification and flash ironmaking process has been stated as a type of multi-generation system, which can be employed to obtain metallic iron and qualified synthesis gas simultaneously. In this study, a separate coal gasification process under the unique conditions of the multi-generation system was investigated using a numerical method. Turbulent flow, heat transfer, and chemical reactions were included in the computational fluid dynamics (CFD) model to predict the internal velocity field, temperature distribution, component distribution, and carbon conversion rate. The simulation results revealed the gasification characteristics in the multi-generation system; these were compared with the results obtained for the traditional gasification process. The sudden expansion structure divided the velocity field into three regions: jet zone, recirculation zone, and plug flow region, in which the stable turbulent structure was formed. The unheated oxidant and inert carrier gas N2 were injected directly to suppress the extremely high temperatures during the pure oxygen-entrained gasification process without a traditional coolant, such as H2O or CO2. A high-quality syngas was obtained with a lower consumption of pure oxygen, and the effective-gas ratio reached 91.73% when the optimum oxygen/coal rate was 0.7. The slender shaft was proven effective for the gasification process to match the subsequent reduction process.

Simulation of the Vibratory Behavior of Slender Shafts Subject to Transverse Loads Moving in the Axial Direction

In various machines of the manufacturing industry, and in particular in paper converting machinery, there are shafts operating under conditions similar to that of a slender beam subjected to a transverse load moving in the axial direction. This condition can lead to vibrations and consequent deterioration of the machine performance and of the product quality. The problem has been theoretically studied in the literature since the 1990s. While shaft mass and stiffness are universally considered among the most influential parameters on its vibratory behavior, less obvious and not investigated in the literature is the influence of the spatial interval between two successive loads, an aspect that should be considered in the shaft design phase. In fact, if that is less than the length of the shaft, i.e., if there is more than one transverse load on the shaft at a given time, the vibration level may decrease with respect to the single-load configuration. This work describes the development of a mathematical model of a slender shaft hinged at its ends, representing the rotor of a paper roll perforating unit, with the SW Mathematica. The effect of a load moving axially at a given speed followed by similar loads after given spatial intervals was simulated investigating the influence of speed and load interval on shaft vibrations and resonance. The results showed how reducing the load interval can lead to a reduction of the shaft vibration which is a useful indication on possible design corrective actions.

Design of Special Lathe for Taper Turning Slender Shaft

Based on the analysis of the machining process characteristics for special slender shaft work-piece, considering the increase in taper turning efficiency and accuracy, a new clamping scheme for machining both ends of slender shaft is put forward, which also includes using pulling tail-stock instead of traditional pushing, using follow-manipulator instead of follow-rest. Following the clamping scheme, the dual drive device, the tail-stock with pulling device and the manipulators are designed, then the parts are integrated into the special lathe for taper turning slender shaft.

The appendicular morphology of Sinoburius lunaris and the evolution of the artiopodan clade Xandarellida (Euarthropoda, early Cambrian) from South China

BackgroundArtiopodan euarthropods represent common and abundant faunal components in sites with exceptional preservation during the Cambrian. The Chengjiang biota in South China contains numerous taxa that are exclusively known from this deposit, and thus offer a unique perspective on euarthropod diversity during the early Cambrian. One such endemic taxon is the non-trilobite artiopodan Sinoburius lunaris, which has been known for approximately three decades, but few details of its anatomy are well understood due to its rarity within the Chengjiang, as well as technical limitations for the study of these fossils. Furthermore, the available material does not provide clear information on the ventral organization of this animal, obscuring our understanding of phylogenetically significant details such as the appendages.ResultsWe employed X-ray computed tomography to study the non-biomineralized morphology of Sinoburius lunaris. Due to the replacement of the delicate anatomy with pyrite typical of Chengjiang fossils, computed tomography reveals substantial details of the ventral anatomy of Sinoburius lunaris, and allow us to observe in detail the three-dimensionally preserved appendicular organization of this taxon for the first time. The dorsal exoskeleton consists of a crescent-shaped head shield with well-developed genal spines, a thorax with seven freely articulating tergites, and a fused pygidium with lateral and median spines. The head bears a pair of ventral stalked eyes that are accommodated by dorsal exoskeletal bulges, and an oval elongate ventral hypostome. The appendicular organization of the head is unique among Artiopoda. The deutocerebral antennae are reduced, consisting of only five podomeres, and bear an antennal scale on the second podomere that most likely represents an exite rather than a true ramus. The head includes four post-antennal biramous limb pairs. The first two biramous appendages are differentiated from the rest. The first appendage pair consists of a greatly reduced endopod coupled with a greatly elongated exopod with a potentially sensorial function. The second appendage pair carries a more conventionally sized endopod, but also has an enlarged exopod. The remaining biramous appendages are homonomous in their construction, but decrease in size towards the posterior end of the body. They consist of a basipodite with ridge-like crescentic endites, an endopod with seven podomeres and a terminal claw, and a lamellae-bearing exopod with a slender shaft. Contrary to previous reports, we confirm the presence of segmental mismatch in Sinoburius lunaris, expressed as diplotergites in the thorax. Maximum parsimony and Bayesian phylogenetic analyses support the monophyly of Xandarellida within Artiopoda, and illuminate the internal relationships within this enigmatic clade. Our results allow us to propose a transformation series explaining the origin of archetypical xandarellid characters, such as the evolution of eye slits in Xandarella spectaculum and Phytophilaspis pergamena as derivates from the anterolateral notches in the head shield observed in Cindarella eucalla and Luohuilinella species. In this context, Sinoburius lunaris is found to feature several derived characters within the group, such as the secondary loss of eye slits and a high degree of appendicular tagmosis. Contrary to previous findings, our analyses strongly support close affinities between Sinoburius lunaris, Xandarella spectaculum and Phytophilaspis pergamena, although the precise relationships between these taxa are sensitive to different methodologies.ConclusionsThe revised morphology of Sinoburius lunaris, made possible through the use of computed tomography to resolve details of its three-dimensionally preserved appendicular anatomy, contributes towards an improved understanding of the morphology of this taxon and the evolution of Xandarellida more broadly. Our results indicate that Sinoburius lunaris possesses an unprecedented degree of appendicular tagmosis otherwise unknown within Artiopoda, with the implication that this iconic group of Palaeozoic euarthropods likely had a more complex ecology and functional morphology than previously considered. The application of computer tomographic techniques to the study of Chengjiang euarthropods holds exceptional promise for understanding the morphological diversity of these organisms, and also better reconstructing their phylogenetic relationships and evolutionary history.

A Node-Dependent Kinematic Approach for Rotordynamics Problems

This paper presents the dynamic analysis of rotating structures using node-dependent kinematics (NDK) one-dimensional (1D) elements. These elements have the capabilities to assume a different kinematic at each node of a beam element, that is, the kinematic assumptions can be continuously varied along the beam axis. Node-dependent kinematic 1D elements have been extended to the dynamic analysis of rotors where the response of the slender shaft, as well as the responses of disks, has to be evaluated. Node dependent kinematic capabilities have been exploited to impose simple kinematic assumptions along the shaft and refined kinematic models where the in- and out-of-plane deformations appear, that is, on the disks. The governing equations of the rotordynamics problem have been derived in a unified and compact form using the Carrera unified formulation. Refined beam models based on Taylor and Lagrange expansions (LEs) have been considered. Single- and multiple-disk rotors have been investigated. The effects of flexible supports have also been included. The results show that the use of the node-dependent kinematic elements allows the accuracy of the model to be increased only where it is required. This approach leads to a reduction of the computational cost compared to a three-dimensional model while the accuracy of the results is preserved.

Study on the three-dimensional temperature field in slender and long shaft grinding process

This paper deals with constructing the mathematical model of the slender and long shaft temperature field in the grinding process. The proposed model is given in terms of a three-dimensional boundary-value problem. The analytic solution is solved by using the Laplace transform, the Fourier transform, the Green’s function method and the Fubini theorem. Finally the model is proposed to be a tool for the control algorithm in slender and long shaft processing.