Engine Gear Research Articles

Phase composition and numerical model of low-pressure pulse carburized layer in 15Cr14Co12Mo5Ni2W steel

Aerospace engine gear steel, 15Cr14Co12Mo5Ni2W steel, requires carburizing heat treatment to achieve operational performance. However, predicting the carbon concentration during the vacuum carburizing process poses significant challenges. This paper aims to design and establish a predictive model for the carbon concentration during the vacuum carburizing process of 15Cr14Co12Mo5Ni2W steel. Given the complex phase transformations during the vacuum carburizing process caused by the ultra-high alloy content of 15Cr14Co12Mo5Ni2W steel, vacuum short-term intense carburization and diffusion experiments were designed. Characterization methods such as XRD, scanning electron microscopy, electron probe microanalysis, EBSD, and FIB+TEM were used to study the microstructure, phase composition, phase constituents, and distribution of element concentrations during the vacuum carburizing process. Subsequently, a carbon concentration distribution calculation model considering carbide changes during the vacuum carburizing process of 15Cr14Co12Mo5Ni2W steel was established. Boundary conditions for carbon absorption during the intense carburization process of 15Cr14Co12Mo5Ni2W steel were proposed, and the relationship between surface carbon concentration and boundary conditions was determined through experiments. Using the method of forward calculation with least squares fitting of experimental data, the diffusion coefficient of carbon in the austenite of 15Cr14Co12Mo5Ni2W steel and the rate of carbon exchange between carbides and the matrix were derived, providing a more precise predictive tool for optimizing the vacuum carburizing process of 15Cr14Co12Mo5Ni2W steel.

AMFGP: An active learning reliability analysis method based on multi-fidelity Gaussian process surrogate model

Multi-fidelity modeling is widely available in theoretical research and engineering practice. Although high-fidelity models often necessitate substantial computational resources, they yield more accurate and reliable results. Low-fidelity models are less computationally demanding, while their results may be inaccurate or unreliable. For the reliability analysis based on complex limit state functions, a method based on active learning multi-fidelity Gaussian process model, called AMFGP, is proposed by combining surrogate model with adaptive strategy, ensuring a balance between prediction accuracy and computational cost in terms of both surrogate modeling and active learning: A dependent Gaussian process surrogate model using complete statistical characteristics is developed under the multi-fidelity framework, and the surrogate performances of different single-fidelity and multi-fidelity models with different learning functions are investigated; based on the proposed model, an adaptive strategy considering the dependence between predictions, the model correlation, and the sample density is designed, and the adaptive performance of different learning functions in different models is explored. The proposed method is validated for effectiveness and adaptability in three mathematical examples with different dimensions and demonstrated for efficiency and practicality in an engineering application to aero engine gear.

Enhanced lipophilicity and wear resistance of 20CrMnTi induced by laser surface texturing

Gear transmission is crucial in mechanical engineering, extensively used in automobiles, ships, machine tools, and airplanes. However, as gear systems advance towards higher speeds, heavier loads, and smaller sizes, the tooth surface becomes more prone to pitting, wear, and other failures. The use of laser surface texturing technology has shown great promise in enhancing the hydrophobic and lipophilic properties of material surfaces. Thus, this paper presents a novel approach for machining equally spaced parallel and perpendicular microgrooves on the surface of gear steels (20CrMnTi) to facilitate lubricant storage and enhance the material’s surface lipophilicity. Laser power and scanning speed are optimized as parameters for laser processing to investigate the lipophilic properties, including the contact angle, diffusion velocity, and contact behavior of oil droplets. Comparative analysis of the processed and unprocessed specimens revealed that both static and dynamic contact behaviors are significantly changed. Compared with the unprocessed specimens, the static contact angle of the processed specimens decreases from 47° to 0° and is super lipophilic at different temperatures; the oil droplet diffusion distance increases by a maximum of 1.27 times; the vertical diffusion height increases by a maximum of 2.8 mm; and the wetting hysteresis coefficient increases by a maximum of 2.55 times. Additionally, the friction coefficient decreases during the stable wear phase, and the wear depth is reduced by 33.53 %. The research has demonstrated that the oil-attracting properties of 20CrMnTi can be greatly enhanced using laser micro-nano texture technology. This improves lubrication conditions and wear resistance, providing a novel approach to mitigating failure risks such as pitting and wear in various gear mechanisms. Furthermore, this method effectively extends the service life of gears, making it a valuable tool for gear engineering applications.

Root cause analysis of flywheel gear failure in a marine diesel engine

Engine gear failures are of significant concern across a wide range of industries. It is important to investigate each gear failure in light of its unique loading and operating conditions for root cause analysis (RCA) and further corrective actions to avoid such failures in the future. The aim of this study was to investigate the premature failure of a flywheel gear of a marine diesel engine and establish the root cause and damage mechanisms using experimental and numerical analysis techniques. A bottom-up creative approach was adopted to assess the loading conditions on the failed gear by first estimating the bending deformation of the failed securing bolt, assuming overload torque on the flywheel caused an equivalent bending moment permanently bending the bolt. Von Mises equivalent stress acting on the gear was numerically estimated as σVM = 737 MPa, which was found significantly more than the specified yield strength of gear governing material AISI 1055 (σY = 550 MPa). SEM fractography revealed a quasi-cleavage failure mechanism in the ‘case’ region near the gear root and a ductile failure mechanism inside the ‘core’ region of the flywheel gear. A crack was found to initiate from the gear root consisting of high-stress concentration under overload stresses. RCA established that the flywheel gears had failed by overload stresses, caused due to overload torque generated from sudden inertial thrust in the internal combustion (IC) engine due to excess fuel throttle opening.

Production Machine Maintenance Analysis Using the Failure Mode And Analysis Method and Logic Tree Analysis d i P T Symgreen Gresik

Maintenance of production machines is a production control to maintain the productivity of the production process. PT. Symgreen is a company that produces ice cream sticks. To achieve optimal results, regular machine maintenance is required. The occurrence of damage to the production machine experienced during the production process, in some damage to machine components, so that production results were reduced. The Failure Mode and Effect Analysis method is used to identify the failure mode and overcome the failure mode in every machine breakdown. To determine the failure mode category for the corrective steps that must be taken immediately and the direction of action that must be chosen to overcome the failure mode, LTA (Logic Tree analysis) is used. The results of the analysis showed that there were 4 machines and 2 types of damage based on the components of the production machine, namely the cutting machine the problem was in a broken bearing with RPN 144 in category B, rotary engine gear cracked RPN 125 category B, rotary engine spindle stuck RPN 125 category B, engine champering gear broke RPN 120 category B, printing machine gear cracked RPN 125 category C. P roposed repairs by performing regular maintenance on machine components, compiling work manuals on each machine.Keywords: Failure Mode, Production Machine, FMEA, LTA, RPN.

Examining Kindergarten Children’s Testing and Optimising in the Context of a Gear Engineering Task

Introducing kindergarten children to the engineering design process (EDP) is an important objective of early STEM education. Studies indicate that children often miss the crucial steps of testing and optimising during the EDP and do not persist in making solutions better. The present study explores how children’s goal awareness, self-evaluation ability, domain-specific content knowledge, spatial skills and intelligence relate to their persistence, testing and optimising behaviour and to solution quality. In a standardized procedure, 41 children (4 to 7 years) in Germany worked on an engineering task in the domain of gears. The engineering process was videotaped, children’s testing and optimising, solution quality, goal awareness, self-evaluation, and task persistence were rated with a coding scheme and with interviewer questions. Domain-specific content knowledge, mental rotation ability and figural reasoning were measured with standardized tests. Correlational analyses indicated that goal awareness was positively related to solution quality. However, most children required support by the interviewer to retrieve the goal specifications. Moreover, children’s self-evaluation was negatively related to task persistence. Most children were satisfied with their first solution, even when it did not meet the requirements. Our findings emphasize the important role of teachers in helping children to tackle challenges with the EDP.

An experimental methodology to study engine gear rattle problems

Gear induced noise represents a major part of overall automotive drivetrain noise. Gear rattle noise is caused by strongly nonlinear dynamic behavior of the gear pair, primarily due to external torque of speed fluctuations under lightly loaded conditions. Such loading conditions cannot be generated by using the conventional gear dynamics test set-ups that employ power recirculating gearbox arrangements or conventional electric motors. In this paper, a new test set-up is introduced to emulate the actual torque/velocity fluctuations of the input and/or output members of a gear train through three-phase synchronous servo-motors. In addition to establishing backlash boundaries, a pair of absolute encoders are used to measure the relative motions of the gears as well as their impacts along the drive and coast sides flanks or gears. Torsional vibratory behavior of a gear pair is presented at different backlash values under several input/output fluctuation conditions along with the companion sound pressure measurements.

Material Selection and Processing Techniques: Crucial Factors for Gear Engineering

Gear drives are susceptible to consistent wear due to repeated cyclic stress around the teeth while in the application. The repeated cyclic loadings have effects on the tribological performance of the components. Also, the downtime data from bottling plants showed that there is a significant increase in gear failure, which resulted in maintenance costs. The contact between a pair of gear in the mesh is complex, which leads to several failure modes like; micropitting, scuffing, micro pitting, and wear as a result of rotation. Materials formed the fundamental elements in which production/manufacturing processes depend on. The selection of materials for high-quality manufacturing depends significantly on the complicated relationship between their properties and manufacturing techniques. Recently, great varieties of materials and processing techniques are available to a gear designer. However, the choice of material and processing methods at a minimized cost poses a challenge to gear designers. In the present study, the importance of material selection and processing methods towards efficient gear design and transmission have been enumerated. Failures associated with materials and processing techniques have also been established as well as the methods of improving the mechanical properties. It is expected that the adoption of the highlighted findings into gear design would result in a reduction of failures and efficient gear transmission.

Prediction of tensile strength in squeeze casted hybrid aluminium matrix composites using conventional statistical approach

ABSTRACT Among non-ferrous materials, aluminium and its alloys are one of the challenging materials having high structural characteristic, superior tribological and mechanical properties and used for the typical applications like carburettor, cylinder, cylinder lid, absorber, engine gear box, side cover, etc. Squeeze casting is one of the simplest processes of manufacturing of composite materials and it attains better advantages of low material processing cost, easy handling of material, size, design and good stability of matrix structure. This work was aimed to develop new hybrid aluminium composites with enhanced tensile strength to support the industries. In this present work, LM24-SiCp-fly ash composite was processed through squeeze casting process. Test coupons were cast with 3 levels and 4 parameters based on Taguchi’s L9 (34) orthogonal array. Influence of process factors on the tensile strength of fabricated component was evaluated and observed that reinforcement percentage and squeeze pressure were the major process parameters affecting the tensile strength. Optimum parametric settings were arrived at by statistical tool for producing the composites with enhanced strength up to 25%. From microstructural study, applying high level of squeeze pressure improved the uniform dispersion, good bonding between the matrix and reinforcement.

Method of precise determination of the main causes of the problems on example of the pin connecting discs in an engine gear

The aim is to present an original combination of methods allowing to precisely determine the main causes of problems. The concept of the method assumes generating as many causes of a problem as possible, grouping them, visualizing, and precisely analyzing to determine the main cause of problem. The method combines the techniques such as Brainstorm, Cause-and-Effect Diagram, Fuzzy TOPSIS method (Fuzzy Technique for Order Preference by Similarity to Ideal Solution) and Fuzzy AHP method (Fuzzy Analytic Hierarchy Process). The method was tested for incompatibilities of products used in the automotive industry. The problem was a crack of the pin connecting discs in the engine gear when grinding. After used the proposed combined method, it was concluded that the main cause of this problem was the poor seating of the grinding wheel on the product. The originality of the article lies in the combination of selected quality management instruments and two fuzzy multi-criteria decision methods within one, consistent method of precisely determining various types of problems (taking into account the problems in the automotive industry).

Eco-Friendly E-Bicycle

As the technology is upgrading itself day-by-day, it makes us dull and unhealthy. So keeping in mind the health benefits and also the cost, we have made an eco-friendly e-bicycle (EFE) for day-to-day transportation. This EFE is a bike with a coordinated compact electric DC gear engine which can be utilized for drive by utilizing power from set of 4 battery-powered batteries. Likewise outfitted with a controller, phone charging port and extras like head light, horn and markers with the most minimal conceivable expense. E-bikes are getting progressively well known all through the planet as an ever increasing number of individuals scan for proficient, reasonable and eco-accommodating methods of transportation. As of late e-bikes have hit the market most in China followed by Europe and USA. Individuals around the globe are going to e-bikes as a powerful answer for their everyday transportation needs. Utilizing an e-bike for this sort of day by day travel can help set aside cash, time and furthermore be worried about the contamination and individual wellbeing.

Influence of Support Structures on the Microstructure and Mechanical Properties of Case Hardening Steel in Laser Powder Bed Fusion

Additive manufacturing, especially laser powder bed fusion (LPBF), enables the manufacturing of complex and lightweight parts. LPBF is a technology with high geometric degrees of freedom, but there are production restrictions, e.g., with regard to overhangs. One strategy to produce these components despite the restrictions is the use of support structures. After the LPBF process the support structures are removed by hand or through machining before general post-processing, e.g., manufacturing of functional surfaces or heat-treatments are concluded. However, support structures change the local process conditions during LPBF depending on the parts geometry (no support structures vs. use of support structures). The influence is mainly caused by the changed heat dissipation of the support structures compared to dense part material. In this contribution, the influence of support structures on the resulting microstructure and the mechanical properties are determined for the case hardening steel 16MnCr5. Case hardening steels are used for gearings and pinions for wide applications in the aerospace industry, e.g., engine gear boxes for helicopters or UAVs (unmanned aerial vehicles). It can be seen that the height of the applied support structures has great influence on the microstructure. Mechanical properties are determined through notched bar impact testing showing an increase in toughness in the as-built state with increasing support structure height. The findings correspond with the increasing content of ferrite seen in the microstructure. The effect of subsequent heat treatments (stress relief annealing and case hardening) on the mechanical properties is also investigated. Furthermore, generalized operating principles for the influence of support structures and the occurring insitu heat treatment in LPBF are presented and described based on the results shown.

Metallurgy and machine building - traditions and innovations

In December of 2019, CNIITMASH celebrates the 90th anniversary. Through all these years, the CNIITMASH team takes and active participation in the development of national machine building, creating new machines and technological processes, doing fundamental research necessary to solve the problems of equipment designing, developing new steel grades and dealing with heat treatment modes to improve materials properties. The information on the stages of formation and development of the Institute presented. Scientific and technical achievements in such areas as creation of fundamentally new technological directions, materials with special properties and equipment for their manufacturing; elaboration of technologies and materials for brand new equipment samples for power and heavy engineering; development of special electro-metallurgy and foundry technologies for nuclear and power machine building etc. The contribution of CNIITMASH into to gear engineering for purposes of heavy machine building, power, transport, defense and other engineering sectors.

Multi-objective optimum design of an aero engine rotor system using hybrid genetic algorithm

A working aero engine rotor system is subjected to multi-objective optimisation using Genetic Algorithm based optimisation. A Hybrid Genetic Algorithm (HGA) is introduced to reduce the weight and unbalance response of the rotor system with constrain on critical speed. The existing aero engine gear box casing vibration is found to be within the critical speed constraint and additional constraints are imposed to move the critical away from this zone. Bearing–pedestal model and Rayleigh damping model are used for accurate results. The optimisation resulted in Pareto optimal solutions and best solution selected using utopia point concept. The outcome of the paper is a comparative study which highlights the advantages of HGA over Controlled Elitist Genetic Algorithm (CEGA) and Goal Programming (GP).

An Analytic Expression for the Inverse Involute

This article introduces new types of rational approximations of the inverse involute function, widely used in gear engineering, allowing the processing of this function with a very low error. This approximated function is appropriate for engineering applications, with a much reduced number of operations than previous formulae in the existing literature, and a very efficient computation. The proposed expressions avoid the use of iterative methods. The theoretical foundations of the approximation theory of rational functions, the Chebyshev and Jacobi polynomials that allow these approximations to be obtained, are presented in this work, and an adaptation of the Remez algorithm is also provided, which gets a null error at the origin. This way, approximations in ranges or degrees different from those presented here can be obtained. A rational approximation of the direct involute function is computed, which avoids the computation of the tangent function. Finally, the direct polar equation of the circle involute curve is approximated with some application examples.

Study on the Reduction of Gear Whine Noise in Diesel Engine Gear Train

Study on the Reduction of Gear Whine Noise in Diesel Engine Gear Train

Nonlinear torsional vibrations of electromechanical coupling of diesel engine gear system and electric generator

New approach for analysis and detuning of nonlinear torsional vibrations of diesel electric generator gear system is suggested. Nonlinear magnetic field of the generator is calculated by finite element method to obtain the disturbing moments, which act on the gear system. Moreover, others disturbing moments, which arise due to operation in diesel engine cylinders, are accounted. Essential nonlinear model of torsional vibrations with sixteen degrees-of- freedom is derived. This model accounts the nonlinear moments of two elastic clutches and the backlashes of gear pairs. The comparison of the numerical simulations data with experimental results is performed to verify the obtained model. The approach for essential nonlinear free torsional vibrations calculations is suggested. The harmonic balanced method is the basis of this approach. Sensitivity theory is used to detune the nonlinear forced torsional vibrations from resonances. The results of nonlinear torsional vibrations analysis are discussed.

An Automatic Thrust Calculation Method in Case of Engine Gear Missing in Flight Control Simulation System

The paper proposes an automatic thrust calculation method in the case of engine gear missing. The trimmed linearization method is used to calculate the equivalent throttle opening between the two gears. An automatic thrust calculation method is presented which uses the equivalent throttle opening as weight coefficient. The speed control system which has introduced the equivalent throttle opening is designed, and the speed is controlled through the combination of the speed control system and the vertical speed control system. In this way, four basic modes are realized in flight simulation——climb, glide, given the yaw angle, given the roll angle, and the special speed control mode. It takes A320 aircraft for an example, the aerodynamic parameters and the Idletrust and Miltrust coefficients are obtained from JSBSim. Carry out flight control simulation on the above modes by building aircraft flight simulation model through Simulink. The results of the flight speed control show that the proposed method can achieve precise control of the speed in multi-flight modes.

Product evolutionary design driven by environmental performance

This article is in terms of product environmental performance demand and proposes four structure evolutionary operation modes which include combined evolutionary method, decomposition evolutionary method, replacement evolutionary method, and material-changing evolutionary method to express the structure evolutionary process of products. Through the quotient space theory and proposed method combined with probability statistics, probability mapping from environmental performance to product structure is established and the evolutionary individuals with outstanding environmental performance are listed. Through the analysis to the specific conditions of the evolutionary individuals, the design constraints are extracted, and the objective function of environmental performance is established. This article presents an interactive genetic algorithm as evolutionary algorithm and combines it with four structure evolutionary operation modes to conduct corresponding gene manipulation and generates evolutionary product. Finally, the proposed methodology is successfully applied to engine gear chamber and the environmental impact is found to be better than before evolution.

Roles of artisanal fishers associations in Ilaje Local Government Area, Ondo State, Nigeria

A study was conducted to determine the artisanal fishers association in Ilaje Local Government area, Ondo State, Nigeria. Multistaged random sampling technique was used to select three hundred and twenty four artisanal fishers‟ association members from the study area. Structured questionnaire and in-depth guided interview were used as instrument for data collection. Data collected were analyzed through descriptive statistic. The study showed that 69.8% had association memberships of more than fifty. Outboard engine 26.9% and boat 21.6% were enjoyed at subsidized rates while only 8.3% each indicated training on outboard engine repair and gear construction and mending. It is recommended that Government at various levels and non- Governmental organizations should assist fishermen associations in the procurement of fishing inputs and organization of different trainings on fishing to boost the local supply from artisanal fisheries.Keywords: Association, artisanal, servicing facilities, membership, training