Behavior Of Shaft Research Articles

Fatigue Strength Assessment of Friction Welds under Consideration of Residual Stress.

A reliable local-fatigue assessment approach for rotary friction-welded components does not yet exist. The scope of this paper is to present test results for the fatigue behaviour of rotary friction-welded solid shafts made of structural steel S355J2G3 (1.0570) and an approach to fatigue assessment considering residual stress. In contrast to fusion-welded joints, components made by rotary friction welding usually contain compressive residual stress near the weld, which can significantly affect the fatigue strength. For this purpose, specimens were welded and characterised, including metallographic micrographs, hardness measurements, and residual stress measurements. The fatigue tests were performed with a constant amplitude loading in tension/compression or torsion with R = -1. All specimens were investigated without machining of the weld flash, either in the as-welded state or after a post-weld stress-relief heat treatment. In addition, the friction welding process and the residual stress formation were analysed using numerical simulation. The characterisation results are integrated into a fatigue assessment approach. Overall, the specimens perform comparatively well in the fatigue tests and the experimentally observed fatigue behaviour is well described using the proposed local approaches.

Investigation on the torsional property of hybrid composite/metal shafts at different service temperatures: Experimental and analytical study

AbstractTorsional tests were conducted to investigate the influence of service temperature on torsional property of composite/steel hybrid structures. In the experiment, two types of lightweight hybrid composite‐metal shafts were tested at both room temperature and various elevated temperatures up to 150°C, including hybrid shafts with and without a metal core. Consequently, the torsional stiffness of the two hybrid shafts at different temperatures was calculated based on the recorded angular deformation‐torque curves. The experimental results revealed a significant decrease in the torsional stiffness of the hybrid shaft without metal core as the increase of service temperature, while the torsional stiffness of the one with metal core remained almost unchanged, especially at high temperatures. In addition, a finite element model was proposed to predict the torsional behavior of the hybrid shafts at different service temperatures. In the model, an empirical equation was introduced, and micromechanical method was adopted to determine the temperature‐dependant elastic properties of composite material and adhesive layer in the hybrid structure. Then, the predicted torsional property was compared to the experimental results for model verification.Highlights Two types of hybrid composite‐metal shafts are designed and manufactured. Torsional tests are conducted at both room and elevated temperatures up to 150°C. A finite element model applicable to shaft at various temperatures is proposed. The temperature‐dependant property is characterized by an efficient equation.

Stress Analysis of Transmission Shafts: A Multi-Faceted Investigation

Transmission shafts constitute pivotal components in mechanical systems, responsible for transferring power from the engine to various mechanisms. The integrity and longevity of these systems hinge on the robustness of transmission shafts, necessitating comprehensive stress analysis. This paper presents an in-depth exploration into stress analysis methodologies applied to transmission shafts. Analytical, numerical, and experimental approaches are scrutinized, with a focus on their efficacy, limitations, and advancements. Material properties, geometric configurations, loading conditions, and manufacturing intricacies are dissected to discern their influence on shaft behavior. Through this comprehensive examination, this paper endeavors to contribute to the advancement of transmission shaft design, ensuring reliability and performance across diverse engineering applications.

추진 축거동 상시 모니터링 시스템 구축에 관한 연구

추진 축거동 상시 모니터링 시스템 구축에 관한 연구

Design, Analysis and Optimization of Composite Propeller Shaft

Most of the automobiles have Rear wheel drive and front engine installation consists of a transmission shaft. Substitution of conventional metallic (SM45C) Propeller Drive Shaft with the composite (CFRP) structure has many advantages. Composite materials have acquired prominence in the engineering industry due to their remarkable strength-to-weight ratio, corrosion resistance, and adaptability. This paper explores the multifaceted process of designing, analysing, and optimizing composite propeller shafts, with a primary focus on their application in marine and automotive industries, aiming to maximize performance while reducing weight. The design phase initiates by establishing precise requirements, encompassing torque loads, rotational speeds, environmental conditions, and safety factors. Material selection is a pivotal decision point, considering factors like fiber type, resin matrix, and layup orientation. Advanced Finite Element Analysis (FEA) technologies are used to simulate the mechanical behaviour of composite propeller shafts under a variety of operational scenarios, assisting in the identification of stress concentrations. Deformations, as well as key failure modes. The design process is iterative. The feedback from these simulations is used to improve the basic design. The analysis phase stress distribution, torsional vibrations, and dynamic behaviour of the composite propeller shaft. A comprehensive study of various layup configurations and boundary conditions is conducted to assess their impact on structural performance and reliability. Additionally, manufacturing considerations, encompassing fabrication techniques, quality control, and cost-effectiveness, are addressed to ensure practical feasibility. The goal of the optimization phase is to lower the weight of the composite propeller shaft while retaining structural integrity and operational reliability. The optimisation outcomes provide information on the best material mix, layup sequence, and geometric factors that achieve the best balance of weight reduction, greater performance and productivity. The findings from this study contribute substantially to the advancement of composite propeller shaft technology, offering engineers valuable insights into the intricacies of design, analysis, and optimization processes. By harnessing the ability of composite materials effectively, industries can realize significant benefits, including reduced fuel consumption, improved efficiency, and enhanced overall system performance, resulting in more sustainable and competitive products for the maritime and automotive sectors.

Effect of material on critical speed of rotor system with varying load

Vibrations caused by the critical speed of the shaft in high-speed machinery can be dangerous and may lead to serious accidents. The current paper presents the study of the effect of shaft material on rotor systems with no load conditions and with load conditions. In this study, lateral vibrations of the shaft bearing coupling are studied. The experimental setup is developed for the measurement of the critical speed of the rotor system. Shafts made of aluminium, copper, and steel materials are considered for testing. The shaft of a length of 910 mm and diameter of 20 mm is considered. An accelerometer sensor along with a data acquisition system is used to measure the frequency response in the shaft. Furthermore, finite element analysis (FEA) is employed to validate the experimentally acquired results about the shaft's behavior. Encouragingly, the outcomes yielded by FEA exhibit commendable congruence with the experimentally obtained data. Notably, the findings demonstrate a discernible decrease in the critical speed of the rotor system when subjected to an eccentric load. This trend is also evident in the experimental results, which align favorably with the analytical projections.

Effects of installation advancement ratio on cyclic uplift response of a single-helix screw pile: experimental and numerical investigation in sand

A screw pile consists of one or several helices connected on a central straight shaft or core. These kinds of piles are widely used onshore and typically installed by applying torque at the pile head with additional vertical compressive force (also referred to as crowd force) if required. Current standards and industrial guidelines recommend that installation follows the pitch-matched approach i.e. advancement ratio AR = 1.0 [1], which means that the pile vertical penetration for each rotation equals the helix pitch, because it is suggested that this leads to reduced installation disturbance.
 where is the vertical penetration per rotation and is the helix geometric pitch.
 Recently this kind of pile has been proposed for upscaling from typical onshore sizes as an alternative silent foundation/anchoring solution for future offshore renewable energy application. This may include use as foundations for jacket structures or anchors for wind turbine in deeper water. However, the increase in pile sizes may require prohibitive vertical force if pitch-matched installation is adopted [2] in sand. One of the solutions to this is over-flighting (AR < 1.0) where the pile is over rotated during installation. When the pile is over-flighted, sand below the helix can move upward through the helix opening resulting in a higher stress and potential densified zone above the helix (Figure 1(a)). The increased stress above the helix can push the pile downward and consequently reduce or even eliminate the vertical installation force. In addition, the increased stress and potential densification in the soil above the helix can result in better monotonic uplift performance [3, 4, 5, 6, 7].
 As foundations for offshore renewable energy applications, the screw piles also need to be able to perform under cyclic loading from wind, wave and current for example. Investigations of uplift cyclic performance of pitch-matched screw pile installation have been reported, but the over-flighting effects have not received significant attention. To give confidence in the maintenance of the beneficial effects of over-flighting on cyclic performance, centrifuge tests and discrete element modelling (DEM) were used in this study. The centrifuge tests provide more reliable physical evidence than 1g tests but are less costly and more accessible than field test. Based on the results of centrifuge test, the DEM models are validated and used to allow separate evaluation of the mechanism of the helix and the pile shaft and assessment of soil state evolution during cycling, which are difficult to capture in field or centrifuge tests.
 The centrifuge tests show that the screw piles installed at lower AR accumulate displacement at lower rates with cycling. which is also captured by the DEM (Figure 1(b)). In addition, DEM suggests that shaft behavior controls cyclic performance because the shaft friction resistance is stiffer than the helix bearing resistance at small displacements. The radial stress on the pile shaft can be enhanced by over-flighting installation. Although it degrades with cycling, the enhanced radial stress due to over-flighting remains higher than that of the pitch-matched pile and therefore the over-flighted piles have improved cyclic performance. On the basis of improved cyclic uplift performance and low vertical installation force, over-flighting installation may be utilized for offshore screw piles performing under cyclic uplift loading where installation forces are a concern or loading is predominantly one-way tensile loading.

Identifying the mechanism of the fatigue behavior of the composite shaft subjected to variable load

This paper presents a finite element analysis of a composite shaft under dynamic variable fatigue loading. The object of this study is the behavior of the fatigue life of a composite shaft under dynamic variable fatigue loading. The fatigue life of the shaft is then determined by analyzing the stress distribution and its effect on the material's fatigue strength. The investigation of fatigue behavior involves evaluating factors such as stress concentrations, fatigue crack initiation and propagation, and the cumulative damage caused by cyclic loading. The study explores the impact of biaxial loading on the shaft's fatigue performance and provides insights into its significance in predicting fatigue life and it is 10e7 cycles. Furthermore, a damage indicator is predicted to assess the accumulated damage and monitor the progression of fatigue-related degradation. This indicator serves as a valuable tool for predicting the remaining useful life of the composite shaft. The equivalent alternative stress is calculated to characterize the combined effect of different loading conditions on the fatigue life of the composite shaft. By quantifying the stress level and variations experienced by the structure, this parameter allows for a comprehensive assessment of the fatigue performance under variable loading scenarios 250 N. The findings of this research contribute to the understanding of fatigue behavior in composite shafts under dynamic variable fatigue loading. The insights gained from the fatigue life investigation, biaxiality indication, damage prediction, and equivalent alternative stress calculation can aid in optimizing design considerations, maintenance planning, and enhancing the reliability and durability of composite shafts in various engineering applications

Extraction of differences in deformation behavior of golf-club shafts with different kick points

Extraction of differences in deformation behavior of golf-club shafts with different kick points

Impact of ground surface movements on ventilation shaft No. 5 of Taimyrsky Mine at Oktyabrsky deposit

The main resources of Taimyrsky Mine represent the high-grade and impregnated ore. The mine field holds some high-grade massive ore bodies and many impregnated ore bodies which occur everywhere except for the south wing of the deposit. The hydrogeological regime of the deposit is governed by the thick permafrost layer. The accesses to the ore bodies is got via vertical shafts: cage shaft KS-3, skip shaft SS-3, ventilation shafts VS-5, VS-6 and VS-7, a backfill shaft (BS) and an air feed shaft (AFS). In the influence zone of mining operations, there are service shafts SS-5, SS-6 and SS-7, BS and AFS, accordingly, shaft headgears, shaft top works and other facilities. The authors estimate the impact of ground surface movements in the course of mining operations on the behavior of ventilation shaft No. 5. The data of the in-situ, as well as geophysical and geodetic survey observations of the study object are presented. All data analyzed, it is possible to reach a conclusion that all damages detected result from the movements and over-weathering of rocks in the space behind the shaft lining. The incorrect engineering estimate of water influx and seasonal watering during the shaft construction led to a drop in the load-bearing capacity of the lining and to suspension of the lining string in rock mass, which created an extra load and induced partial failure of the lining. At the present time, shaft VS-5 is in the process of the lining reconstruction, complete grating of the space behind the lining and erection of segmental lining from top downward. Based on the research findings, the detected movements are also typical of neighbor shaft VS-6. It is required to undertake a fully integrated survey of the shaft and make provisions for its loadbearing capacity recovery to avoid an adverse situation.

Computer aided numerical damage analysis of the axle shaft

Today, while transportation is constantly moving forward, costs are increasing. The aim is to obtain light structures that are suitable in terms of weight, sufficient in strength, and to save materials and energy. Axles are not only used in transport vehicles, but also in buses, automobiles and forklifts. Axles must be of a reliable structure due to their place of use. The external effects that the axles are generally exposed to are the applied loads. In this study, the mechanical damage analysis of the axle shaft and the characteristic changes in steel materials as a result of static loading were investigated numerically. In order to observe the mechanical behavior of the axle shaft under various loading conditions, mechanical tests should be supported by numerical analysis. Because the physical causes of damage development can be understood through numerical analysis. The aim of our study is to reach the most suitable values in the design of the variables with the optimization technique of the axle shaft made of AISI 1035 steel. Optimum values were obtained by performing numerical analyzes of the axle shaft designed with Solidworks program. As a result of the analysis, it was observed that deformation occurred at the ends of the axle.

Changes in Propeller Shaft Behavior by Fluctuating Propeller Forces during Ship Turning

It is known that a ship’s shafting system can be adversely affected by hull deformation, variations in the engine power, the propeller load, and eccentric propeller thrusts, thereby increasingly affecting the behavior of the shaft’s movement. A deformed shafting system may also lead to a potential risk of bearing damage by causing a change in the local load of the rear part of the after-stern tube bearing of the propeller shaft. With this concern, a series of previous studies were focused on optimizing the effects of hull deformation by securing a proper level of propulsion shaft stability and optimizing the relative inclination angle and oil film retention based on a quasi-static state, that is, Rules for the Classification of Steel Ships and experiences of shipyards. However, despite our efforts to resolve this issue, marine accidents involving stern tube bearing damage have continued to occur under relatively unattended ship motions in a transient state, that is, a quasi-static state that can possibly cause sudden stern flow field changes. Therefore, to improve the stability of the propulsion shaft, it is necessary to understand ship motions and the conditions of shafting systems in a dynamic state and a transient state when the system is designed. From this point of view, this study investigated the effect of changes in eccentric propeller forces on the motion of the propeller shaft in a representative transient state of a 50,000 deadweight tonnage tanker by means of the strain gauge method and a displacement sensor. The research findings demonstrate that propeller thrust fluctuations have a direct effect on the shaft stability by significant changes in the shaft motion that can lead to unbalanced supporting loads on the stern tube bearing. These results clearly reproduce the cause of damage to the ship in which the accident occurred at a reliable level and will be a reference for establishing pragmatic guidelines for preventing damage to similar ships in the future.

Experimental Study on the Force Characteristics of Superlong Pile Groups in Silty Sand

Laboratory model testing of single pile and superlong pile groups in saturated silty sand was conducted to investigate the response and bearing behavior of superlong pile groups with a high or low cap under vertical loads. The load transfer mechanism and bearing behavior of the pile shaft were discussed in detail. The load‐settlement curve of the loaded superlong pile groups belongs to the type of gradual descent in silty sand. The transferred load decreased along the pile length during loading, but the gradients differed in different positions of the superlong pile group foundation with a high or low cap. The maximum shaft friction of the superlong pile groups with a high and low cap is about 2.5 times and 1.8 times, respectively, than that of the single pile. In addition, the tip resistance of the piles in the pile group foundation is about 2–3.5 times that of the single pile. The friction resistance of the superlong pile group foundation with a low cap was slightly larger than that of the high cap in the entire pile length, and two peaks and one peak, respectively, were observed. Under the ultimate load, the pile‐soil maximum relative displacement of the friction on the pile side in the silty sand stratum was about 3% of the pile diameter. Under the ultimate load, the load sharing ratio of the pile side resistance of the two types of pile group foundations was about 60% of the total load. The load sharing ratios at the pile tip of the superlong pile groups with high and low caps are 40% and 33%. Furthermore, equations were proposed to determine the axial capacity of the superlong pile group based on the single pile bearing capacity and were applied to analyze the test pile. The calculated ultimate bearing capacity was similar to the measured value, with a maximum error of only 4.88%, thus validating the proposed method.

Parameter Interval Uncertainty Analysis of Internal Resonance of Rotating Porous Shaft-Disk-Blade Assemblies Reinforced by Graphene Nanoplatelets.

This paper conducts a parameter interval uncertainty analysis of the internal resonance of a rotating porous shaft–disk–blade assembly reinforced by graphene nanoplatelets (GPLs). The nanocomposite rotating assembly is considered to be composed of a porous metal matrix and graphene nanoplatelet (GPL) reinforcement material. Effective material properties are obtained by using the rule of mixture and the Halpin–Tsai micromechanical model. The modeling and internal resonance analysis of a rotating shaft–disk–blade assembly are carried out based on the finite element method. Moreover, based on the Chebyshev polynomial approximation method, the parameter interval uncertainty analysis of the rotating assembly is conducted. The effects of the uncertainties of the GPL length-to-width ratio, porosity coefficient and GPL length-to-thickness ratio are investigated in detail. The present analysis procedure can give an interval estimation of the vibration behavior of porous shaft–disk–blade rotors reinforced with graphene nanoplatelets (GPLs).

Investigation of dynamic behavior of Hollow Rotor Shaft System through FEM

Generally, there is two kinds of rotor system used for transforming the power from one source to another, one is solid rotor system, and another is the hollow rotor shaft system. In comparison to solid shaft, the hollow shaft is of less weight, for a given diameter and length. In addition, the hollow shaft has a larger Strength to weight ratio and has a greater polar moment of inertia. Thus, they can transmit more torque compared to solid shafts. The main purpose of this paper is to analyze the dynamic behavior of hollow shafts with a particular interest in estimation of damping. This study also evaluate the dynamic response of different rotor thicknesses at various speeds where hollow shafts and solid shafts modelled through ANSYS 16. The proposed analysis performed in both frequencies as well as time domains, in which the Campbell diagram, the critical speed, and the orbits are numerically determined. Further, this study also illustrates the convenience of the hollow shafts at different inner diameters for rotor dynamics applications. The analytical results (ANSYS 16) were validated through the experimental results.

Dynamic analysis of a flexible shaft in a scroll compressor considering solid contact and oil film pressure in journal bearings

Abstract Solid contact between the shaft and sleeve is a frequent failure mode in scroll compressors because of the large gas forces and high operating speeds required to meet the demands of compact size and high efficiency. In this paper, the dynamic behavior of a shaft with four degrees of freedom is analyzed considering gas, centrifugal, bearing, and contact forces. Oil film pressure of the journal bearing is determined by applying the finite element method to the Reynolds equation. When contact between the shaft and sleeve arises from flexible and rigid motion of the shaft, the contact force is calculated by applying asperity contact theory. Equations of motion of the shaft are developed using a finite element model of a Timoshenko beam and solved with a central difference method. To verify our analysis, we compared our results with those of previous studies and the results of commercial program analysis for each step involved in validating journal bearing, contact force, and dynamic behavior of a rigid shaft. The flexibility of a shaft and the contact between the sleeve and shaft should be taken into account when predicting the dynamic behavior of the shaft in a scroll compressor.

A Study on the Dynamic Behavior of a Vertical Tunnel Shaft Embedded in Liquefiable Ground during Earthquakes

Since liquefaction was first observed in South Korea during the Pohang earthquake, public concerns regarding the seismic stability of major infrastructure have increased substantially. However, the seismic behavior of tunnel shafts, which are an important element of tunnel structures, has not been properly established, especially under liquefiable soil conditions. In this study, 3D numerical modeling with Fast Lagrangian Analysis of Continua in 3 Dimensions (FLAC3D) was performed to predict the dynamic behavior of a vertical tunnel shaft during liquefaction. This study demonstrates key aspects of the dynamic behavior of tunnel shafts by varying important parameters such as the thickness of the liquefiable soil layer and applied seismicity level. Moreover, important dynamic responses such as excess pore pressure generation, the seismic bending moment of the shaft, and lateral displacements are highlighted. Finally, meaningful discussion of the seismic risk analysis based on damage indices is conducted based on the analysis results.

Two-Way Coupled Shooting Analysis of Fluid Force in the Annular Plain Seal and Vibration of the Rotor System

Abstract In turbomachinery, the rotor dynamic (RD) fluid force generated in a fluid element, by the interaction between the shaft behavior and the fluid flow, is one of the causes of the shaft behavior and has a great influence on the stability of the turbomachinery. In order to improve the reliability of turbomachinery, it is important to analyze the dynamical behavior considering the mutual influence of the RD fluid force and shaft motion. In this paper, the two-way coupled analysis between the fluid force in the annular plain seal and the vibration of the rotor system was expanded by introducing the shooting method in it. The frequency response was obtained, and the onset speed of instability (OSI) was predicted effectively. The influence of parameters on the OSI was investigated and discussed. Then, the numerical results obtained by this two-way coupled shooting analysis was compared with the experimental results and the validity of the analysis was confirmed. The influence of disturbance on the error of predicted OSI was also discussed. The transition region to instability was introduced for the predicted OSI using the spectral radius, and the error between the numerical and experimental results of the OSI was explained. As a result, the two-way coupled shooting analysis can predict the OSI values in various situations of two-way coupled system more effectively than the direct numerical simulation. Also, the robustness of stability for the predicted OSI can be evaluated simultaneously by investigating the spectral radius and defining the transition region to instability appropriately.

Centrifuge modelling of rock-socketed drilled shafts under uplift load

Rock-socketed drilled shafts are widely used to transfer the heavy loads from the superstructure especially in mountainous area. Extensive research has been done on the behavior of rock-socketed drilled shafts under compressive load. However, little attention has been paid to uplift behavior of drilled shaft in rock, which govern the overall behavior of the foundation system. In this paper, a series of centrifuge tests have been performed to investigate the uplift response of rock-socketed drilled shafts. The pull-out tests of drilled shafts installed in layered rocks having various strengths were conducted. The load-displacement response, axial load distributions in the shaft and the unit skin friction distribution under pull-out loads were investigated. The effects of the strength of rock socket on the initial stiffness, ultimate capacity and mobilization of friction of the foundation, were also examined. The results indicated that characteristics of rock-socket has a significant influence on the uplift behavior of drilled shaft. Most of the applied uplift load were carried by socketed rock when the drilled shaft was installed in the sand over rock layer, whereas substantial load was carried by both upper and lower rock layers when the drilled shaft was completely socketed into layered rock. The pattern of mobilized shaft friction and point where the maximum unit shaft friction occurred were also found to be affected by the socket condition surrounding the drilled shaft.

A high-cycle fatigue failure analysis for the turbocharger shaft of BELAZ 75131 mining dump truck

Fatigue fracture is one of the most common causes of failure in many rotating machinery components. In this paper, the fatigue behavior of a typical shaft, which is widely used in the turbocharger of BELAZ 75131 mining dump trucks, is studied both theoretically and experimentally. There is one diameter change along the shaft and investigations show that the dominant cause of failure is fatigue caused by cyclic loadings. The fatigue life of the shaft subjected to cyclic bending loads is analytically estimated according to the modified Goodman, Gerber, ASME-elliptic and Soderberg criteria. Finite element based numerical simulations are also performed by MSC Fatigue software to demonstrate the accuracy of the experimental results. In addition, a fatigue testing machine is developed to obtain the fatigue life of the shaft experimentally and validate the theoretical results. The effect of constant torsional loading and the fillet radius at the diameter change on the fatigue life of the shaft under a cyclic bending load is also studied.