Shaft Model Research Articles

Stability of Hydrogen Turbopump Rotor Shaft Axially Self-Balanced

Abstract Controlling the vibration levels of turbopump rotor shafts is a key feature for the reliability of space engines. Turbopump components are exposed to high static and dynamic stress levels, and therefore are particularly sensitive to high-cycle fatigues. Among the numerous dynamic excitations that affect the turbopump, self-induced instabilities are the most critical ones because of the exponential growth rate of vibration levels. These flutter-like phenomena may account for rotor shaft instabilities of turbopumps designed with an axial balancing system (ABS). Such a system is necessary to avoid heavy static loads on bearings and is commonly used in high power turbopumps in the space industry. It consists of a fluid cavity located in the back of a centrifugal compressor. Instabilities induced by the ABS have been studied within the framework of a research and technology program using a reduced scale hydrogen turbopump demonstrator called TPtech. This paper focuses on experimental and numerical analysis of rotor instabilities induced by the ABS. A coupled dynamic model of the rotor shaft and the ABS cavity is presented. It shows instabilities of the rigid rotor axial mode, but also of an axisymmetric rotor mode. This result is consistent with the data acquired during TPtech test campaign. The instability mechanism is complex as it involves the rotor modes, the flow in the ABS cavity, and its acoustic modes. Therefore, TPtech tests performed in representative conditions are valuable. They have permitted tool validation and have provided design rules to prevent occurrence of such phenomena.

The Effect of a Local Injection of Flurbiprofen Ester Microspheres on Systemic Inflammatory Model Rats With a Closed Femoral Shaft Fracture.

Background: Periarticular injections with a combination of local anesthetics, non-steroidal anti-inflammatory analgesics (NSAIDs), and epinephrine are becoming increasingly popular in the perioperative analgesia of artificial joint replacement. However, data on the efficacy and safety of local injection NSAIDs are still scarce. The purpose of this study was to investigate the efficacy and safety of a local injection of Flurbiprofen Ester Lipid microspheres into the inflammatory model of femoral shaft closed fractures in rats. Methods: A systemic inflammatory model was induced in SD rats (60) by closed femoral shaft fracture; 12 non-fractured rats were used as the blank control group (group A). The systemic inflammation model of 60 rats was divided into 5 groups (12 in each group); Group B: intramuscular injectionof the same amount of normal saline at different time points as a negative control; Group C: intravenous injection of Flurbiprofen Ester microspheres (4.5 mg/kg) at different time points; Group D: intramuscular injection of Flurbiprofen Ester microspheres (2.25 mg/kg) at different time points; Group E: intramuscular injection of Flurbiprofen Ester microspheres (4.5 mg/kg) at different time points; Group F: intramuscular injection of Flurbiprofen Ester microspheres (9 mg/kg) at different time points. The behavioral test observed the behavior of the rats. Then, the inflammation factors of CRP, IL-6, COX-1, COX-2 and TNF-αby ELISA were recorded. Results: Through the behavioral test it could be found that the effect of the intramuscular and intravenous injections of Flurbiprofen Ester microspheres was similar. Fracture rats with a local injection of Flurbiprofen Ester microspheres showed lower inflammation levels measured by COX-1, CRP, and TNF-α compared with the control group. Pathological sections at 24, 48, and 96 h after surgery did not display any local muscle necrosis at the local injection site. These findings suggested that a Flurbiprofen Ester microsphere muscular injection exhibited a similar effect to an intravenous injection. Conclusion: The local injection of Flurbiprofen Ester microspheres significantly reduced the inflammatory response in fracture rats and did not increase the risk of muscle necrosis, suggesting its feasibility in local injection analgesia.

Dynamical characteristic validation of motorized CFRP spindle unit based on receptance coupling

Carbon fiber reinforced plastic (CFRP) is used in machine tool components to provide high specific stiffness with high damping properties and low thermal expansion; further, it is combined with metals in specific ratios to enable the use of existing equipment and machine design. The development of CFRP spindle shafts has design flexibility in the stacking sequence. The improvement and analysis of spindle unit dynamics are essential for achieving high productivity in machining, and prediction methods for dynamic stiffness with lower computational costs are required to estimate and optimize the machine performance of the design proposals. Therefore, parameter identification for the equivalent physical properties of composite materials with CFRP and steel was proposed in this paper to use general solutions for a one-dimensional Timoshenko beam model. Four different analytical models of the CFRP spindle shaft following the actual development phase were designed via generalized receptance coupling to multi points in order to observe the model shapes. The frequency response functions and mode shapes of the spindle shaft models were compared with those of finite element methods and impact tests. The spindle shaft model reflecting the applicable location of CFRP in the rotational axis demonstrates a sufficient estimation accuracy for natural frequencies and mode shapes. The spindle shaft model reflecting the stacking sequence demonstrates robustness against the parameterization errors of the CFRP. A motorized CFRP spindle unit was modeled by combining a spindle shaft model and bearing models; the bearing dynamics were experimentally studied under heat radiation after stopping the spindle rotation. Moreover, a steel spindle shaft model and several types of CFRP layout with the same dimensions were compared on the spindle unit model; the CFRP spindle unit yielded a greater dynamic stiffness. The layout of the CFRP application and requirements on manufacturing are discussed for the further improvement of the dynamic stiffness.

Torque Transmission Law of Wind Turbine Drive System under the Excitation of Uneven Wind Load

A random wind speed time history model based on Weibull distribution is constructed. According to the known mean and variance of wind speed, the time fitting curve of random wind speed is obtained through MATLAB simulation method. According to the wind speed range of the actual operation of the wind turbine, the obtained wind speed curve is transformed, and then according to the obtained relationship between the wind speed of the wind turbine and the input torque, the input time-varying torque of the actual operation of the wind turbine is obtained. Establish the rigid shaft model of the wind turbine gearbox, calculate the gearbox transmission ratios at all levels, and then obtain the torque output curves of the gearbox planetary stage, medium-speed stage, and high-speed stage under random wind speed input to study wind power the torque transmission law of the machine drive system. The ability to better analyse the transmission structure of the gearbox and the torque transmission law of key components has a certain significance for the design and manufacture of the wind turbine transmission chain.

Analysis of thermal error model of ball screw feed system based on experimental data

In order to investigate the effect of thermal expansion on the ball screw feed system (BSFS) of a precision machine tool, theoretical modeling of and experimental study on thermally induced error are focused in this paper. A series of thermal experiments are conducted on the machine tool to measure the temperature of the main heat source and measuring points of BSFS. This study is to classify the main heat sources and discuss the impact on the ball screw feed system separately. By the experimental data of ball screw system, the thermal model of screw shaft in the axial direction is analyzed and verified. Based on the heat generation and transfer analysis of ball screw system, thermal expansion of screw shaft in the axial direction is modeled mathematically. In addition, by analyzing the effects of machining parameters such as rotational speed, preloads, and lead, we get the parameter influence of BSFS’s temperature rising and thermal deformation. This work can help us reduce thermal deformation effectively and improve the precision of CNC machining.

Probabilistic Method to Estimate the Scatter of the Fatigue Strength of Shafts in the HCF Region

The fatigue strength of shafts is always subjected to scatter. Knowledge of this scatter is essential—especially in the high-cycle-fatigue (HCF) region—for producing safe shaft designs. Experimental determination is extremely time consuming and cost intensive. Therefore, this paper investigates the possibility of quantifying the scatter of (nominal) fatigue strength in the HCF region by means of a probabilistic model. The basis for establishing such a model is the identification of the parameters influencing the damage mechanism. In this context, the scatter-influencing parameters of external shape, surface and material condition were statistically modelled in a suitable manner. These influencing parameters act as input parameters in a local strength approach in addition to non-scattering parameters. Using a probabilistic model developed on the basis of Monte Carlo simulations, models of shafts and their surfaces can be randomly generated. The shafts so generated are submitted to local strength verifications by means of finite-element analyses of the entire failure-critical shaft surface. The stochastically generated shafts and the application of nominal stresses simulate the experimental testing at different nominal stress levels. By statistical evaluation of these fictitious nominal stress levels with respect to calculated failures and run-outs of the shafts, the probability distribution of the fatigue strength of the shaft population—and thus its scatter—can be determined. The probabilistic model is validated using a shaft population under non-scattering rotating bending load and compared with the experimentally determined scatter of the fatigue strength.

“Fatigue Analysis Of Epoxy Composite Material Reinforcement On Propeller Shaft”

Propeller shaft, also known as propeller shaft is the most important component to any power transmission application; automotive propeller Shaft is one of this. A propeller shaft is a mechanical part that transmits the generated torque by a vehicle's engine into motive force which is usable to propel the vehicle. Substituting composite structures for metallic which is structures has many advantages because of higher specific stiffness and strength of composite materials. This work deals with the conventional replacement of steel propeller shafts with fiberglass epoxy composite propeller shaft for an automotive application. The parameters of design were optimized with the objective of minimizing the weight of a propeller shaft. The design optimization also improves the performance of propeller shaft. Present work deals with FEA analysis of composite shaft with different degree of orientation of glass fibers. It includes the modeling of shaft in CATIA. The meshing and boundary condition application will be carried using Hypermesh, Fatigue analysis of composite shaft will be carried out using ANSYS.

Some problems of xFEM modelling of surface crack growth in a turbine shaft

One of the major problems in numerical simulation of fatigue loading represents the generation of a finite element mesh, since the model with crack cannot use combinations of different types of mesh elements (such as HEX or TET). This paper presents the problem of the generated FE mesh during fatigue simulation of the Kaplan Turbine Shaft model in ABAQUS and Morfeo Crack software packages. The model contains an initial crack of 37 mm. Simulation was performed in order of assessing the integrity of shaft with crack. During the first attempt, a fined mesh in the vicinity of the crack was used, which did not prove to be effective in obtaining satisfactory results. FE whose size was similar or the same as the FE around the fatigue crack growth domain were used in the second attempt. After remeshing, the numerical simulation proved to be successful and gave more realistic results.

Weight Optimization of Drive Shaft Using Various Composite Materials in FEA

In sesctor of Automobile Engineering the power transmission through the shaft is very much important and in any power transmission, the drive shaft plays very important role. The torque generated through the engine of vehicle is converted in usable motive force and transmitted a drive shaft, is a mechanical part that transmits the torque generated by a vehicle's engine into usable motive force to propel the vehicle. By replacing the composite structure with conventional metallic structure one can achieve more advantages with respect to the strength and specific stiffness which is very high in composite material. In current study the fiber composite, fiber glass epoxy and hybrid material is used instead of conventional metallic drive shaft. The optimized design parameters is induced with the composite drive shaft which give the objective of reduction in weight of the drive shaft as well as it enhance the overall performance of the drive shaft. Present work deals with FEA analysis of composite shaft with different composite material. It includes the modeling of shaft in CATIA. The meshing and boundary condition application will be carried using Hypermesh; Structural analysis of composite shaft will be carried out using ANSYS. Composite shaft will be fabricated and tested to validate with numerical values.

Building 3D model for the deep vertical shaft in Nui Beo coal mine using Terrestrial laser scanning technology

Nowadays, deep vertical shafts have been built normally in Vietnam’s underground coal mines. During the operation of the underground coal mines, the deep vertical shafts must check periodically. With the advantages of fast measurement, high accuracy, point cloud data, the ability to process data by other specialized software, etc. Terrestrial laser scanning technology has allowed building 3D models for deep vertical shafts and used for other different purposes. In this present, by using Topcon's equipment and software, the process of establishing a 3D model for the main vertical shaft of the Nui Beo coal mine at a depth of 400 m was indicated. The simulation results have the cumulative error of sampling interval of stations not more than 4 mm, and the average position deviation of the aim direction relative to the vertical is 8.3 mm.

Fault Feature Analysis of Gear Tooth Spalling Based on Dynamic Simulation and Experiments.

Gear dynamics analysis based on time-varying meshing stiffness (TMS) is an important means to understand the gear fault mechanism. Based on Jones bearing theory, a bearing statics model was established and introduced into a gear system. The lateral–torsion coupling vibration model of the gear shaft was built by using a Timoshenko beam element. The lumped parameter method was used to build the dynamic model of a gear pair. The dynamic model of a spur gear system was formed by integrating the component model mentioned above. The influence of rectangular and elliptical spalling on TMS was analyzed by the potential energy method (PEM). The fault feature of tooth spalling was studied by dynamic simulation and verified by experiments. It is found that the gear system will produce a periodic shock response owing to the periodic change of the number of meshing gear teeth. Due to the contact loss and the decrease of TMS, a stronger shock response will be generated when the spalling area is engaged. In the spectrum, some sidebands will appear in the resonance region. The results can provide a theoretical guide for the health monitoring and diagnosis of gear systems.

Fiber Optic-Based Thermal Integrity Profiling of Drilled Shaft: Inverse Modeling for Spiral Fiber Deployment Strategy.

The current state of practice to interpret the thermal integrity profiling (TIP) data of drilled shaft is the so-called effective radius method. It uses the concrete pouring log and average temperature to construct a relationship between temperature distribution and effective radius that can be used to reconstruct a drilled shaft model. While this effective radius method is computationally inexpensive and has good operationality, it is not good at predicting the dimensions and shape of shaft defects. Upgrading the sensor used in conventional TIP from thermocouples/thermal wires to fiber optic sensors, the spatial resolution of the measured temperature will be enhanced. By using the newly proposed spiral fiber deployment strategy, we can improve the reconstruction of shaft defects in the integrity testing of drilled shafts. The corresponding inverse modeling of defected shaft reconstruction for spiral deployment is proposed in this paper based on the temperature distribution pattern that is learned from forward modeling. Through inverse modeling, the details of defects in drilled shafts can be reconstructed numerically. An analysis of the results shows that the prediction by inverse modeling has good agreement with the forward modeling set up initially. This work helps the evolution of the TIP from the nondestructive testing stage to the quantitative nondestructive evaluation stage.

Rotation Accuracy Analysis of Aerostatic Spindle Considering Shaft’s Roundness and Cylindricity

The rotation accuracy of the aerostatic spindle can easily be affected by shaft shape errors due to the small gas film clearance. Thus, the main shaft shape errors with the largest scale—that is, the roundness and cylindricity errors—are studied in this paper, and a dynamic mathematical model is established with the consideration of the roundness, cylindricity errors, and spindle speed. In order to construct the shaft model, the discrete coefficient index of the shaft radius based on roundness measurement data are proposed. Then, the simulation calculations are conducted based on the measured cylindricity data and the constructed shaft model. The calculation results are compared with the spindle rotation accuracy measured using the spindle error analyzer. The results show that the shaft with a low discrete coefficient is subjected to less unbalanced force and smaller rotation errors, as obtained by the experiment.

Artificial intelligence-based public healthcare systems: G2G knowledge-based exchange to enhance the decision-making process

With the rapid evolution of data over the last few years, many new technologies have arisen with artificial intelligent (AI) technologies at the top. Artificial intelligence (AI), with its infinite power, holds the potential to transform patient healthcare. Given the gaps revealed by the 2020 COVID-19 pandemic in healthcare systems, this research investigates the effects of using an artificial intelligence-driven public healthcare framework to enhance the decision-making process using an extended model of Shaft and Vessey (2006) cognitive fit model in healthcare organizations in Saudi Arabia. The model was validated based on empirical data collected using an online questionnaire distributed to healthcare organizations in Saudi Arabia. The main sample participants were healthcare CEOs, senior managers/managers, doctors, nurses, and other relevant healthcare practitioners under the MoH involved in the decision-making process relating to COVID-19. The measurement model was validated using SEM analyses. Empirical results largely supported the conceptual model proposed as all research hypotheses are significantly approved. This study makes several theoretical contributions. For example, it expands the theoretical horizon of Shaft and Vessey's (2006) CFT by considering new mechanisms, such as the inclusion of G2G Knowledge-based Exchange in addition to the moderation effect of Experience-based decision-making (EDBM) for enhancing the decision-making process related to the COVID-19 pandemic. More discussion regarding research limitations and future research directions are provided as well at the end of this study.

Dynamics Modeling and Experimental Investigation of Gear Mechanism with Coupled Small Clearances.

Internal gear mechanism is widely used in micro-nano satellites due to its compact structure and high precision transmission. However, the vibration coupling caused by the small clearance coupling is more obvious and cannot be ignored under low speed, light load and zero gravity conditions. Based on the geometric relationship between radial clearance and backlash, a coupled model between dynamic backlash and radial clearance of internal meshing gear is established. Based on the conformal contact theory, the radial collision force model of the gear shaft and shaft sleeve considering the small clearances is established. Additionally, a multi-clearance gear rotor system test device is built to measure the vibration acceleration of the internal gear rotor system by an acceleration sensor and transmitted to the industrial computer through a signal collector for data processing. Through the comparison of simulation and experiment, the accuracy of the gear dynamics model is verified. The analysis results show that, compared with the traditional model, the calculation results of the gear mechanism model considering the small clearance coupling is closer to the experimental data.

Use of electromechanical analogies in the construction and calculation of a simulation model of the process of torsional oscillations of the shaft line of an internal combustion engine

The purpose of the article is to substantiate the possibility of using electromechanical analogies in the construction and calculation of parameters of the simulation model of the process of torsional oscillations of the internal combustion engine shaft, which will allow to move from mechanical models of shafts to their electrical counterparts. Results of the research. The article clarifies the relationship between phenomena occurring in mechanical and electrical systems, mechanical and electrical analogues are established, namely force is considered as electromotive force or voltage, velocity as current, moment of inertia as inductance, spring flexibility as capacitance, coefficient friction as electrical resistance, and the kinematic scheme of the shaft line is presented in the form of a diagram of a reactive bipolar, the parameters of which are determined during analytical calculations of the kinematic scheme of the elastic system. The concept of dynamic stiffness is introduced, which is similar to the concept of reactive resistance of a bipolar. The initial data for the calculation of a linear system in which it is assumed that the pliability of the shock absorber is zero. Conclusions. According to the results of the analogies, the parameters of the simulation model were obtained. The calculation of the elastic system using the method of electromechanical analogies allowed to build a simulation model of the shaft line of an internal combustion engine.

Physical Simulation Test on Temperature Field Distribution of Artificial Vertical Straight Multirow Freezing Inclined Shaft

This study investigated the temperature field distribution of a freezing inclined shaft. Thus, a three-dimensional physical simulation test system was developed, and the system consists of six parts, which are simulation box and shaft model, loading system, freezing system, external environment simulation system, and data acquisition system. From the results of physical and mechanical property test of artificially frozen sand, in the range of 25°C to -20°C, the heat capacity of sand decreases first, then increases, decreases, and finally tends to be stable; the thermal conductivity of sand gradually increases and finally becomes stable; and the cohesion, internal friction angle, uniaxial compressive strength, and elastic modulus of artificially frozen sand all increase as the freezing temperature decreases. The three-dimensional physical simulation test and field measurement showed that the distance from the freezing pipe is the main factor affecting freezing wall temperature, and the closer to the freezing pipe, the faster the cooling rates. Comparison of theoretical calculation results and field measurement results shows that the calculation formula of freezing wall temperature with time of the inclined shaft can reflect the general law of freezing wall temperature cooling. Therefore, the 3D physical simulation test system is reliable and the test method is feasible.

Energy Analysis of the Propulsion Shaft Fatigue Process in a Rotating Mechanical System Part III Dimensional Analysis

Abstract This article presents the third and last part of the problem of diagnosing the fatigue of marine propulsion shafts in terms of energy with the use of the action function, undertaken by the authors. Even the most perfect physical models of real objects, observed under laboratory conditions and developed based on the results of their research, cannot be useful in diagnostics without properly transferring the obtained results to the scale of the real object. This paper presents the method of using dimensional analyses and the Buckingham theorem (the so-called π theorem) to determine the dimensionless numbers of the dynamic similarity of the physical model of the propulsion shaft and its real ship counterpart, which enable the transfer of the results of the research on the energy processes accompanying the ship propulsion shaft fatigue from the physical model to the real object.

Three-dimensional Modeling and Performance Analysis of Permanent Magnet Synchronous Motor

The three-dimensional model of rare earth permanent magnet synchronous motor is built based on SolidWorks software, the assembly of synchronous motor and the production of explosion diagram are completed. Finally, the motor shaft model is imported into the Workbench interface ANSYS the finite element analysis software for harmonic response and modal analysis. The results show that the motor shaft model resonates under the action of 659.38hz exciting force, the displacement value of deformation is the largest in the middle of the shaft, the maximum stress appears near the keyway of the shaft end; The first four natural frequencies and modes from modal analysis. This research provides some reference value for improving the performance of synchronous motor.

Physical Model Test of Artificial Freezing-Inclined Shaft

Based on the vertical straight artificial freezing engineering in Northern Shaanxi, a three-dimensional (3D) physical simulation test system was developed, consisting of six parts, which are simulation box, shaft model, loading system, freezing system, external environment simulation system, and data acquisition system. The physical model and actual test results show that the 3D physical simulation test system is reasonable and reliable. The test model results show that the distance from the freezing pipe significantly affects the freezing wall temperature. For the case of four adjacent, two adjacent tangential freezing, and two adjacent axial freezing pipes, the cooling rates were 1.37, 2.79, and 1.96°C/h, respectively. The field measurement showed that the proximity to the freezing pipe increases the cooling rates. The cooling rates of points 1k#, 2k#, and 3k# were 25.61, 25.32, and 25.35 mm/d, respectively. The increment rates of vertical and horizontal freezing pressures with temperature were 8.78 and 2.97 kPa/°C, respectively. Furthermore, the freezing pressure time fitting formula was given. The calculated results of temperature and freezing pressure are consistent with the measured results, indicating the reasonability and reliability of the 3D physical simulation test scheme of the artificial freezing-inclined shaft in this work.