Shaft Failure Research Articles

Failure Analysis of the Short Drive Shaft in a Screw Press Machine

The screw press is a type of machine press used for extracting crude palm oil from the oil palm’s mesocarp, where its short driveshaft, a mechanical component for transmitting torque and rotation, is often found to be susceptible to failure. Since the initial damage to the short driveshafts in the shaft keyway area is associated with the frequent incidence of shaft failure, this research aimed to discover the root cause of this failure and how to prevent it using visual inspection and stress analysis methods as well as those of the fractography, metallography, chemical composition, and hardness tests. Using the descriptive method to analyse the collected data, the visual inspection and the fractography results of the research indicated that the fatigue crack failure of the short drive shaft in the palm oil screw press machine was caused by the fatigue crack initiation that was safe from stress concentration in its keyway areas. This crack initiation was followed by crack propagation as indicated in beach mark forms. Finally, the ductile fracture observed on the shaft surface was found to have resulted from the continuous rotational motion and the loading and unloading effect of the central shaft driving system.

Fatigue Failure Analysis of a Speed Reduction Shaft

The mining industry sector is notable for the severe service loads and varied environmental conditions that it imposes on its equipment and mechanical systems. It has become essential to identify the causes of failures and use the information to avoid similar failures and improve projects. In this paper, a study on shaft failure in a speed reduction box was carried out. A section of a fractured shaft made of hardened austempered steel was analyzed to determine the cause of the break. Fractography was performed to characterize the failure mode on the fracture surface. The microstructural analysis and hardness profile revealed that the shaft was inadequately heat treated, resulting in low resistance microstructures and the development of a thin layer of bainite at the shaft edge. Large amounts of inclusions were found in the fracture region, and the tensile tests revealed that the material had an elongation below the specification. The analyses showed that the combination of factors of a large amount of inclusions present in the low resistance banded structure, and the presence of concentrated pores in that same region, acted in a synergistic way to decrease the fatigue resistance and fatigue life of the shaft material.

Crack growth models for multiaxial fatigue in a ship’s propeller shaft

A premature fatigue failure of a large intermediate propeller shaft in a shuttle tanker is discussed and analyzed. The short fatigue life consists mainly of a crack growth phase. Life predictions are carried out by crack growth modelling based on engineering fracture mechanics. The purpose of the present investigation is to identify the most likely loading modes based on the evolution of the crack propagation. A Linear Elastic Fracture Mechanics Model (LEFM) is applied with the stress intensity factor range entering the Paris law as a key parameter. Existing formulas for the geometry functions are supplemented by more detailed stress intensity factor calculations pertaining to small semi-elliptical surface cracks subjected to stress mode I. Enhanced geometry functions are proposed as a function of the relative crack depth and the crack shape aspect ratio. The ability of the fracture mechanics model to reconstruct the observed crack path and crack shape development is emphasized. Various loading modes and multi-axial stress states are applied to pursue the observed crack behavior. The observed semi-elliptical crack shapes and the shift in crack planes are included in the analysis.

Failure analysis of screw shaft in screw compressor

This paper analyses the root causes of screw shaft failure in screw compressors. The failure mechanism was studied by visual inspection, macro- and microfractography, chemical characterization, and mechanical property analysis. The results reveal that the main reason for the failure was multisource fatigue due to the lack of surface quenching at the fracture position of the shaft root. To prevent similar failures, better control of surface quenching is strongly recommended.

Control Valve Condition Checking by Spectral Analysis

The research work considers and analyzes the problem of control valve failure in case of shaft-gear break during normal operation. In order to identify typical deviations and causes of failure of the electrically driven valves, the amplitude-frequency spectra of the current signal taken at one or more phases of the electric motor were analyzed. The method of spectral diagnostics adopted for analysis allows detecting hidden defects of reinforcement not detected in other types of analysis. In order to justify the study, spectral analysis is carried out on control valves installed in the main condensate and feedwater systems of power units WWER-1000 and WWER-1200. As a result of the study, the following relationships were established increase of amplitude speed of electric motor (EM) to -30 dB is a fact of EM operation at increased load, which will lead to wear of thrust-radial bearings; appearance of baseband frequencies in the region of 50 Hz frequency indicates that there are deviations in setting of electric drive torque limiters. The detected defects, in the future, will lead to the failure of the gear shaft and the shutdown of the power unit. The results of the performed work are used to supplement the existing catalog of defects of pipeline valves developed by RI NPE VETI NRNU MEPhI.

An Investigation of Shaft Failure on Induced Draft Fan in A Steam Power Plant

A failure phenomenon on induced draft fan (IDF) shaft became a crucial attention in Power Plant with capacity 350 MW because the failure is catastrophic without early warning information. Also, the failures on the IDF shaft occurred in a short period within two months. This paper reported an investigation and evaluation of the root cause of the failure by vibration data monitoring and material analysis. The objective of the investigation and evaluation is to identify the main root cause and specific symptoms of IDF shaft failure. According to the data collection and analysis result, each phenomenon indicated an identical vibration pattern, however, the duration of each step is different. A series of tests of shaft samples was carried out to get comprehensive information, such as chemical composition test, tensile test, hardness test, microstructural examination (SEM), and fractography examination. The shaft repair procedure was also evaluated. The results were showed that multi initial of micro-scratch and martensitic embrittlement played an important role in the shaft failure. Micro-scratch triggered high-stress concentration on shaft surface. Martensitic embrittlement was found on weld metal and heat-affected zone.

Failure criterion for concrete shafts in deep alluvium zones based on plastic ultimate strain and its application

The failure of vertical concrete shafts in the deep alluvium zones is always a troublesome technical problem in coal mines. There is lack of practical failure criteria for such shafts. Therefore, the method of establishing failure criteria of shafts based on the method of ultimate strain was proposed. By regarding concrete as a frictional geomaterial, the formula for the plastic ultimate strain of concrete was constructed according to the theory of generalised plastic mechanics. Furthermore, the ultimate strain when concrete failure was determined using numerical limit analysis method. The numerical limit strain analysis method can be used as a quantitative failure criterion for a concrete shaft. It can directly determine the limit state and failure position. By exploring the shaft deformation during the reduced groundwater level of quaternary aquifers by applying numerical limit analysis method, the failure procedure of concrete shaft was reproduced. It was revealed that the damage to the soil around the shaft preceded that to the shaft; the reduction in groundwater level of aquifers can damage the shaft, while the stress-relief groove delays the failure of the shaft and shifts the failure zone to a greater depth. On condition that water level decreased by 25 m, the sand layer at a burial depth of 158–174 m was damaged; in the case that water level was reduced by 27 m, the shaft at a burial depth of 181–182 m was damaged. After setting a stress-relief groove on the shaft, failure occurred when the groundwater level was decreased by 38 m, implying that the stress-relief groove can release the vertical stress on the shaft.

Predicting the durability of piston engine crankshafts

A method for testing crankshafts of automobile and tractor engines under the action of variable bending moment is proposed. The test machine consists of a frame on which the crankshaft is installed through elastic springs on the extreme root necks. On the extreme necks, pendulums are installed, one end of which is rigidly fixed, and at the opposite ends of the pendulums, two inertial (unbalanced) vibrators are installed, creating two equal forces in the horizontal plane, directed in opposite directions and changing their magnitude. This pair of forces creates a variable bending moment relative to the axis of the crankshaft, acting on all its elements, and causes fatigue failure in the weakest sections. Based on the test results, a graph is plotted in the coordinates of maximum stress – the number of loading cycles before failure, which allows you to determine the parameters of the crankshaft fatigue life model.According to the corrected linear hypothesis of fatigue damage accumulation, shaft failure occurs when the sum of accumulated damage is equal to a certain value, which is determined by the results of fatigue tests.

Fatigue Failure Analysis of Pump Shaft of a Hydraulic Coke Removal System

Failure of pump shaft (P116-1) of high-pressure water pump occurred during coke removal. Shaft material (3Cr13) demonstrated yield and tensile strength of 737 and 910 MPa, respectively. Failure analysis was performed to determine the cause of failure, which was a fracture at the pump shaft located at the journal. Macroscopic, metallographic, chemical composition, hardness, SEM, and EDS analyses were used in the failure analysis. Metallographic and SEM analyses revealed that fatigue cracks are related to corrosion and geometrical shape. Fatigue crack initiation at the disconnected area of the chromium plating layer weakened fatigue resistance. Causes of incomplete chromium plating at the shaft journal and keyway should be investigated further.

Misalignment Detection of a Rotating Machine Shaft Using a Support Vector Machine Learning Algorithm

Fault diagnosis for rotating machinery is important for reliability and safety, and shaft misalignment is one of the most common causes of mechanical vibration or shaft failure. In this study, we detected defects caused by misalignment of the shaft axis in rotating machinery using an artificial intelligence machine learning technique for fault recognition. Unlike other methods that focus on the time domain, we changed vibration data in the time domain to the power spectrum component value in the frequency domain. Then, the power spectrum values​ were classified using principle component analysis (PCA). Based on the results, defects are determined using a machine learning technique that uses a support vector machine (SVM). The results show that defects can be quickly determined from only vibration data about normal and abnormal states. By using the proposed pre-processing method, the machine learning framework based on vibration data can be effectively applied to diagnosis not only shaft defects but also faults of other rotating machines such as motors and engines

A review of various techniques used for shaft failure analysis

This paper examines the various methodologies utilized by various writers for shafts failure research in different applications. This document compares and contrasts the numerous methodologies employed, as well as their application and limitations, as presented by various writers. The goal of this project is to investigate the various approaches for shaft failure analysis and to select the optimum methodology for shaft failure analysis in a gear box installed on an overhead crane to avoid repetitive failure. This review paper gives the insights of various analysis carried out to find shaft failure. Roller Shaft failures can be optimized by preventive mechanical maintenance techniques & using safe design with proper manufacturing processes. The various literatures has been systematically compared and reviewed to get a proper shaft failure analysis. Every method has its pros and cons and used by specific industrial segments. Shaft failure causes the unnecessary shutdowns and leads to heavy production loss. The objective of this paper is to study various shafts failure analysis and select the best method to find out the root because failure of heavy nip roller shaft used in textile industry.

Study on failure of transmission shaft based on finite element and fracture analysis technology

Due to the harsh driving environment, the power transmission components of military vehicles are subjected to long-term alternating loads and sudden impact loads. A failure analysis of the transmission shaft of a military truck was carried out. By constructing a mechanical simulation analysis model of the transmission shaft, the dynamic response of the structure under alternating stress and impact load is solved. Then the cause and mechanism of drive shaft failure were analyzed. Using fracture analysis technology to discuss the phenomenon of bearing sleeve cracking, circlip rupture and flange fork deformation. It indicates that caused by overload, foreign matter between the shaft and the needle etc., which ultimately leads to the failure of the universal joint transmission. Finally, the optimal design of the drive shaft is proposed.

Crack detection in a rotary shaft analytical and experimental analyses: A review

Detection of depth of cracks and its positions is the broad region of investigator over the universe. The article discussed a critical review of recent research done on crack identification and localization in rotary machine shaft using experimental modal analysis. Crack detection and localization in rotor shaft is very essential in various engineering applications. An enormous vibration in a rotary shaft causes premature failures of machine components. It is required to recognize the damage in time to avoid catastrophic failure of rotary machine shaft. Experimental investigation is used to observe their vibration characteristics like natural frequency of vibration, damping and mode shapes of structures. Natural frequency of rotary shaft can be obtained using the modal analysis technique. Also trained machine learning (ML) based artificial neural networks (ANN) can be applied to detect crack depth and its location. From the review by different research papers, it is observed that a lot of the research has been done on rotary machine shafts with open transverse cracks. Excessive speed and frequency for identified cracks position as well as cracks depth can be used to train an ANN. By using ML based artificial neural networks, location of cracks, and its depth identified precisely.

Failure analysis of a broken SA564 stainless steel pump shaft

Shafts are rotating elements that are subjected to torsion and bending moments that cause failures at times leading to personal injury, capacity loss, or poor product quality if basic preventive design actions are not taken. Against this background, this paper describes the failure analysis and root cause of a broken SA564 grade stainless steel pump shaft used in a plant through visual inspection, metallography, X-ray diffraction, scanning electron microscope, chemical analysis, hardness, tensile and non-destructive tests. The results show that creep, fatigue initiation and propagation from defects in the material during the operation were the predominant factors of pump shaft failure. Moreover, the existence of voids, micro-cracks, sensitisation and creeps were also identified on the broken shaft. Overall, the studied broken shaft of the impeller failed due to fatigue, initiated at the fillet radius of the keyway due to the high cyclic stress loading.

Fatigue life analysis of wind turbine gear with oxide inclusion

AbstractConsidering a great deal of wind turbine gear failure cases, it is shown that the oxide inclusion has been one of the main reasons for the failure of the gear shaft under fatigue loading condition. In this paper, the fatigue behaviour of gears involving oxide inclusion under real operating condition is investigated. A three‐dimensional finite element model for helical gear pair applied in the middle stage of wind power increasing gearbox is established, and the fatigue life of nonmetallic inclusion zone of middle gear shaft is predicted using Miner's theory and real load spectrum of wind power growth gearbox. Then, the effects of several factors (such as the size and position of oxide inclusion and residual stress induced by manufacturing) on the fatigue life of gears with inclusion are studied. The results show that both inclusion size and position have great influence on the fatigue life of gears, and the compress residual stress will prolong the fatigue life of gears. Furthermore, the critical safety line and safety region of gears with oxide inclusion have been obtained for three representative inclusion positions. The present work is expected to provide a guidance for the engineering design and life safety evaluation of wind turbine gears.

Failure of a Cooling Water Pump Shaft

This study investigates the failure of an industrial cooling water pump which experienced a drive shaft failure. As per the fail-safe design, during adverse loading of the shaft, key should fail by shear. The key, if fails, can be easily replaced to resume the operation of the pump. However, this investigation reveals that both the key and the shaft failed due to materials processing issues. A detailed failure analysis was carried out including design calculations, visual inspection, dye penetrant inspection, magnetic particle inspection, hardness test, microstructural analysis, and fractography. The study found that the hardness of the shaft varied radially from the core to the surface. The subsurface of the shaft near the keyway, happened to be significantly softer than the key. During operation, the keyway widened by plastic deformation and caused rattling of the key. Due to rattling and vibration, the key developed numerous fatigue cracks and eventually failed by crack linkages. The shaft eventually failed by torsional shear near the midpoint of the keyway. The analysis adjudged hardness variation in the shaft due to materials processing issues as the root cause of the failure.

Revamping Shaft Design for Combating Fatigue Failure

This paper gives insights on the failure analysis of the non-drive shaft of a conveyor in a coke plant of an integrated steel plant. The failure of the shaft was investigated in order to determine the root cause and contributing factors. Investigation methods included visual examination, optical and scanning electron microscope analyses, chemical analysis of the material, mechanical tests and life calculations based on design. The overall appearance of the fracture surface of the 45C8 grade shaft indicated rotating bending fatigue failure from a step location. Microstructural analysis revealed a crack from the sharp step and no metallurgical abnormalities. Apart from the metallurgical analysis, the design of shaft was also verified by calculating step profile, fillet radius and calculated stress in actual condition. It revealed that a shaft with a minimum diameter of 70 mm, made of 45C8 steel, can withstand the actual stress acting on it. In this design, the shaft diameter was found to be 65 mm which is insufficient to bear the actual stress. Shaft failures can be reduced by preventive mechanical maintenance and using safe design. To enhance the shaft life without an increase in shaft diameter, we recommend that the material be changed to 42CrMo4 grade steel, which, when appropriately heat treated, has higher stress limit, along with a modification in the step profile with a proper fillet radius.

Analysis of Screwed Shaft Failure using the Process Simulation of Loaded Torsion

The paper present the result of the study on the use of simulation software of ANSYS R15.0 version in attempt to simulate the load which is working on a screwed shaft of a shaping machine. This shaft was broken down during normal working and within limit of its life time. Therefore, the simulation would try to find out the cause of the failure. In order to simulate the load, the mechanical properties and chemical composition of the shaft were used as the input for modeling. The shaft is made of medium carbon steel of S 45 C in round shape. The finite element method (FEM) was used for analyzing. The modeling was started with a 3D redrafting the real dimension of the shaft in a computer aided design (CAD) model, then imported to the ANSYS system into FEM format. The mechanical and physical properties of the material was entered as the engineering data. Meshing was made to divide the component into several small elements. A combination of static and torsion load was applied to the shaft with a fixed position. The simulation results shown that von mises stress of 4.546 MPa was achieved. While, the first principal stress of 4.518 MPa, the third principal stress of 0.538 MPa. Other result revealed that the displacement was 0.001602 mm. Simulation also indicate that failure occurs at the slot a place where the pin was inserted to lock between the shaft and the bevel gear. The result is in accordance with the real failure of the shaft. To conclude, the ANSYS with FEM modeling has succeeded to simulate the failure of the screwed shaft.

Case study of failed feed water pump shaft in HRSG of 9F gas turbine generator unit

The failure of feed water pump shaft failure uesed in HRSG (heat recovery steam generator) of 9F class gas turbine generator unit has been systematically investigated in terms of visual inspection, fractographic, chemical component, micro structure and mechanical properties analysis using optical microscope (OM), scanning electron microscope (SEM) equipped with energy-dispersive X-ray (EDX) analysis, transmission electron microscope (TEM), elemental analyzer and universal tensile testing machine, respectively. Results suggest that the failure of feed water pump shaft was typical multiple-origin fatigue fracture resulting from torsion stress, owing to the lower mechanical properties caused by the less alloying element and alloy strengthening phase (ε-Cu, η-Ni). A detailed analysis of the micro structure revealed the existence of severe microsegregation and coarse M23C6 carbide at the grain boundaries, which accelerated the nucleation of micro holes and led to the formation of microcracks at the junction of micro holes. This failure analysis can help identification of root cause and its elimination with corrective measures undertaken.

Failure analysis of rear axle shaft of a heavy vehicle

Failure of the rear axle shaft of a heavy vehicle was thoroughly investigated. It was noticed that the axle shaft had failed during service and broken into two pieces. Different types of investigations were carried out on the failed axle shaft which includes visual examination, chemical analysis, Mechanical testing, Fractography and ultrasonic testing. Several cleavages were noticed in the Fractography, which depicted a sign of brittle fracture. Fatigue striations were observed in scanning electron microscopic analysis of the as received failed axle, which a typical indispensible characteristics of fatigue failure. The tensile fracture surface revealed mixed component of dimple as well as cleavage facet. Results indicated that failure occurred due to sudden loading on the axle shaft. The shear stress in the weak portion of the axle was not sufficient to counter the stress imposed by sudden loading.