Diesel Engine Cylinder Head Research Articles

A feature and optimized RRT algorithm-based assembly path planning method of complex products

Currently, manufacturing enterprises lack strict regulations and plans for complex products. The actual assembly path mainly relies on technicians’ experience, leading to an unreasonable assembly path for each part at the workstation, an unreasonable transportation path across the workstation, and the problem of mutual interference between parts. To solve these problems, this paper studies the assembly path planning technology of complex products based on the basic geometric features and assembly sequence information. The complexity of assembly path planning is reduced by converting the assembly problem into a disassembly problem. The disassembly direction and distance of each part are determined based on the geometric feature type of each mating face, and the rapid disassembly of the assembly body is achieved. The Rapidly-exploring Random Trees (RRT) algorithm is optimized by target-tendency and double random tree strategy, and the optimal assembly path of each component is quickly generated by combining the path optimization method and interference checking method. Finally, the effectiveness of the proposed method and the superiority of the path planning algorithm are verified using the cylinder head of a Marine diesel engine (MDE) as a case study.

Research on fatigue reliability assessment of engine cylinder head based on neural network

Fatigue reliability (FR) evaluation is crucial for extending the service life and improving the reliability of automotive engines. This study proposed a general framework for assessing high cycle FR based on the back propagation neural network (BPNN). Using a diesel engine cylinder head (CH) as an example, the stochastic finite element analysis was implemented by considering the uncertainties of materials and loads. Subsequently, the stochastic finite element calculation process was replaced with the BPNN model to expedite fatigue life prediction. Ultimately, the reliability assessment of the CH was conducted, taking into account the influence of the load sequence. The research findings indicated that the reliable life t0.95 of the CH considering the load sequence was approximately 75 h, representing a 7.1% increase compared to the linear cumulative damage. During the service life of the CH, the failure probability sensitivity factor for the gas force load exceeded 0.9, offering an important reference for optimizing FR.

Fault States Diagnosis of Marine Diesel Engine Valve Based on a Modified VGG16 Transfer Learning Method

The marine diesel engine is an important power machine for ships. Traditional machine learning methods for diesel engine fault diagnosis usually require a large amount of labeled training data, and the diagnosis performance may decline when encounters vibrational and environmental interference. A transfer learning convolutional neural network model based on VGG16 is introduced for diesel engine valve leakage fault diagnosis. The acquired diesel engine cylinder head vibration signal is first converted to time domain, frequency domain, and wavelet decomposition images. Secondly, the VGG16 deep convolutional neural network is pretrained using the ImageNet dataset. Subsequently, fine tuning the network based on the pretrained basic parameters and image enhancement methods. Finally, the well‐trained model is adopted to train and test the target dataset. In addition, the cosine annealing learning rate setting method is used to make the learning rate close to the global optimal solution. Experimental results show that the proposed method has higher accuracy and better robustness against noise with a small sample dataset than traditional methods and deep learning models. This study not only demonstrates a novel view for the diagnosis of marine diesel engine valve leakage, but also provides an applicable diagnosis method for other similar issues.

Diesel engine small-sample transfer learning fault diagnosis algorithm based on STFT time–frequency image and hyperparameter autonomous optimization deep convolutional network improved by PSO–GWO–BPNN surrogate model

Abstract Aiming at the problems of complex diesel engine cylinder head signals, difficulty in extracting fault information, and existing deep learning fault diagnosis algorithms with many training parameters, high time cost, and high data volume requirements, a small-sample transfer learning fault diagnosis algorithm is proposed in this article. First, the fault vibration signal of the diesel engine is converted into a three-channel red green blue (RGB) short-time Fourier transform time–frequency diagram, which reduces the randomness of artificially extracted features. Then, for the problem of slow network training and large sample size requirements, the AlexNet convolutional network and the ResNet-18 convolutional network are fine-tuned on the diesel engine time–frequency map samples as pre-training models with the transfer diagnosis strategy. In addition, to improve the training effect of the network, a surrogate model is introduced to autonomously optimize the hyperparameters of the network. Experiments show that, when compared to other commonly used methods, the transfer fault diagnosis algorithm proposed in this article can obtain high classification accuracy in the diagnosis of diesel engines while maintaining very stable performance under the condition of small samples.

Reliability study for diesel engine cylinder head through fatigue failure analysis and structural optimization

Crack and failure are often captured in the cylinder head of diesel engine during high cycle fatigue test. In order to study the cause and improve the fatigue resistance, tensile test, metallographic observation and fracture analysis were carried out. In addition, the finite element method was applied to simulate the stress distribution and fatigue strength of the cylinder head. Meanwhile, the influence of load factors on the fatigue strength was analyzed. The structure was optimized on the finite element analysis. The results show that the material properties are not the main cause of cylinder head failure. High cycle fatigue failure of cylinder head is identified by the reason of working loads. Among the causes affect fatigue strength, gas force was determined as the dominant factor by changing stress amplitude, while thermal load as the secondary factor by changing mean stress. Additionally, the structural optimization measures for the cylinder head were put forward according to the failure causes, and the safety coefficient of the vulnerable parts was increased from 0.88 to 1.04, meeting the design requirements. This study can provide a reference for the engine reliability analysis.

Identification of start of combustion based on contribution level of principal component in vibration signal of cylinder head surface

The surface vibration signal measured from diesel engine cylinder head is caused by in-cylinder pressure (ICP) excitation and non-combustion excitations. These excitation response signals are coupled together, which increases the difficulty of identifying combustion information from the vibration signal. Furthermore, there always exists a phase deviation between the identified phase combustion parameter and the theoretical value, which decreases the recognition accuracy of combustion parameter. To accurately extract the combustion information, this paper firstly simulates the vibration signal caused by the combine of ICP, piston side pressure, piston slap and reciprocating inertial force of an SD2100TA diesel engine. Then, the principal component analysis (PCA) is introduced to analyze the contribution level of the combustion excitation response signal in the vibration signal under different working conditions. Meanwhile the influence of measuring point position and number on the contribution level is also discussed. Results show that the contribution level decreases gradually with the increase of the rotation speed and slightly increases with the increase of the torque. In addition, the contribution level is higher when the measuring point is farther away from adjacent cylinder. Finally, the relationship between the contribution level and the identified phase deviation of the start of combustion (SOC) is analyzed, and the deviation correction method is proposed. Results show that the maximum error of SOC after correction is within ± 1 deg.

Microstructure based analysis and predictive modeling of cast Al7Si1.5Cu0.4Mg alloy mechanical properties

The heterogeneity of microstructure leads to non-uniform distribution of mechanical properties, which is also related to strength and reliability degradation of components. Taking diesel engine cylinder heads as an example, this study investigated the relationship between microstructures and tensile mechanical properties of cast Al7Si1.5Cu0.4Mg alloy with different temperatures, including secondary dendrite arm spacing (SDAS), grain size, eutectic silicon morphology. The results indicate that the mechanical properties of cast Al7Si1.5Cu0.4Mg alloy have a strong correlation with the microstructures. Based on the linear regression analysis method, several predictive models were established to quantify the tensile mechanical properties of cast Al7Si1.5Cu0.4Mg alloy with different microstructures. The Hall-Petch model was used to capture the relation between microstructure parameters and yield strength, and a linear relationship model was employed between the hardness and yield strength. The prediction model of ultimate tensile strength was proposed based on the relationship of microstructure and hardness. In addition, considering the error limit of the Hall-Petch relationship, the upper threshold of grain size and SDAS is calibrated. By considering the influence of the material's plastic deformation ability and the material strength on fatigue performance, a novel Tensile-Fatigue Bridge Model was proposed. The model provides a reference for the mechanical properties prediction work of thin-walled small parts and also contributes to the strength evaluation of components with non-uniform microstructures.

Тепловое и напряженно- деформированное состояние чугунной крышки цилиндра

Based on the FEM calculation, the choice of cast iron with vermicular graphite for the cast cylinder head of a transport diesel engine when it is converted into a ship's one is justified.

Fatigue life prediction analysis of high-intensity marine diesel engine cylinder head based on fast thermal fluid solid coupling method

Fatigue life prediction analysis of high-intensity marine diesel engine cylinder head based on fast thermal fluid solid coupling method

Analysis of a diesel engine cylinder head failure caused by casting porosity defects

The diesel engine failed in the bench test due to the cracking of its cylinder head, which is made of aluminum alloy by low pressure sand casting. To investigate the cause of the cylinder head cracks, computed tomography (CT), metallurgical observation and fracture inspection were carried out. Besides, the stress state of the cylinder head was determined by finite element analysis method, and the casting process was simulated to identify the root cause of the cracks. The cracks are observed to be mainly concentrated at the intake/exhaust channel and the cooling water channel, especially at the partition wall between them. At the partition wall, the cracks mostly initiate from the outside wall and propagate to the interior surface, some of which have penetrated the partition wall. The cylinder head failure is promoted by multiple cracks initiated in casting porosity defects, independent of the loading condition, as proved by the results of finite element method and crack morphology. Furthermore, the formation of casting porosity defects in the cylinder head is caused by poor local cooling conditions during the casting process.

Constitutive equation of compacted graphite iron (GJV450) at high temperature and high strain rate

Compacted graphite iron (CGI) is an ideal material for the cylinder block and cylinder head of diesel engine because of its excellent physical and mechanical properties. At present, the researches on CGI mainly focused on experimental study of machining CGI, there are few studies on the cutting simulation of CGI, especially the high-speed machining simulation of CGI, and the constitutive equation of CGI at high temperature and high strain rate has not been studied. In this paper, the stress-strain relationship under quasi-static condition was obtained by quasi-static tensile test, and the power law constitutive equation of CGI with a grade of GJV450 under the condition of large strain, high strain rate, and high temperature was built by orthogonal cutting experiments and finite element iteration. The established power law constitutive equation was applied to the finite element simulation of the cutting process of CGI, which improves the accuracy of finite element analysis. The chip morphology of CGI and the distribution of plastic strain and temperature in the cutting process were analyzed by finite element simulation.

Misfire Fault Diagnosis Method for Diesel Engine Based on MEMD and Dispersion Entropy

As a main source of power, diesel engines are widely used in large mechanical systems. Fire failure is a kind of common fault condition, which seriously affects the power and economy of the diesel engine. Previously, scholars mostly used single-channel signal to diagnose the misfire fault of the diesel engine. However, the single-channel signal has limitations in reflecting the information of fault. A novel fault diagnosis method based on MEMD and dispersion entropy is proposed in this paper. Firstly, the multichannel vibration signal of the diesel engine cylinder head is decomposed by multivariate empirical mode decomposition (MEMD), which obtains the IMF component groups with the same frequency in the same order. Then, the IMF component with a large correlation coefficient with the original signal in each group is selected to reconstruct new signal, and dispersion entropy (DE) of the reconstructed signal is calculated as a fault feature vector. Finally, the fault feature vector is input into the support vector machine (SVM) for misfire fault classification. Compared with the other three methods, the results show that the diagnosis method proposed in this paper can effectively extract the fault features and accurately identify the fault type, which is superior to the comparison method.

Structural and Thermal Analysis on Cylinder Head of VCR Diesel Engine Using ANSYS

The present work is to study the structural and thermal characteristics of cylinder head of Variable Compression Ratio (VCR) Diesel engine under different loads. The geometrical model of cylinder head is prepared using CATIA. The experiments were carried out at compression ratios of 16.5, 17.5 and 18.5. The results of stress-strain developments, heat flux and temperature variations at different loading conditions were simulated using ANSYS. From the results of analysis, the minimum values of critical stresses, heat flux and maximum factor of safety are obtained at 16.5 compression ratio.

Thermo Structural Analysis on Cylinder Head of 4 Stroke VCR Diesel Engine

The main aim of the project is to analyse the design performance of VCR 4 stroke Diesel engine cylinder head at the compression ratio 16.5 using Ansys software. The basic modelling is done on CATIA V5 software. The design exposition can be done structurally and thermally in ansys. By the structural analysis the maximum and minimum von misses stress, total deformation can be determined, the maximum gas pressure required for this analysis is taken from the experimental set up of VCR engine. With the steady state thermal analysis we will get the maximum temperature distribution and total heat flux of the cylinder head with the initial pressure value. The results of both the expositions are used to decide the critical areas of the cylinder head which require further amendment and also the quality of design. If the maximum stress is less than the material strength of the cylinder head then the basic design criteria can be achieved.

On the issue of improving the reliability of the cylinder head of the diesel engine

Cylinder head in a modern diesel engine is one of the most complex structurally loaded parts of its cylinder-piston group. The cylinder head is one of the most damaged units that determine the terms of scheduled repairs of the entire engine and, ultimately, the level of costs to maintain its performance. Article gives a review of studies on the cylinder head refinement of a diesel engine 5D49 (ChN26/26), and especially its main part which is the fire deck of the combustion chamber. Design disadvantage of the fire deck is the close location of the holes of the exhaust and intake valves, the inclined location of the nozzle. Depending on the heating and on the degree of constraint of the deformation of the head element, i. e. the absence of its free expansion, during heat exchange the process of destruction of the fire deck elements proceeds, which is characterized by the accumulation of fatigue damage in the material and plastic deformations. Studies have shown that under stationary loading conditions with the same scale of alternation of heating and cooling, the head should provide failure-free and durable operation. The occurrence of cracks due to the accumulation of residual stress should be attributed to the share of random "bursts" of temperature and temperature stresses arising during transient processes. These processes occupy approximately 20 % of the total engine operating time. One of the main reserves for improving the reliability of heads is to prevent exceeding thermal loads in operation by optimizing transient processes and increasing the uniformity of cylinder loading. The cylinder head of the 5D49 (ChN26/26) diesel engine type, apparently, has outlive the possibilities for a significant increase in reliability and service life and bringing it into line with operational requirements. For use on new engines, a new head must be developed — symmetrical with a central vertical arrangement of the nozzle, and with a well-thought-out cooling circuit.

Simulation research on the thermal-mechanical coupling of YSZ thermal protective coatings prepared by laser-plasma composite heat source on the surface of high-intensity diesel engine cylinder head

To improve the reliability of the coating, a laser-plasma composite heat source was used to prepare the YSZ coating. Based on the thermo-elastoplastic finite element theory and using ANSYS simulation software, a numerical model of laser-plasma composite heat source for YSZ coating was established. The model took into account the thermophysical performance parameters of the material at different temperatures and the latent heat of the phase transition of the material. The paper focused on the value and distribution of the temperature and the residual stress of coatings when the powder deposition temperature was 300 °C, 500 °C, 700 °C, and 900 °C. The results showed that with the increase of powder deposition temperature, the maximum temperature of the component increased. The micro-metallurgical morphology existed at the interface between the coating and the substrate prepared by the laser-plasma composite heat source. With the increase of powder deposition temperature, the depth and width of the molten pool of the substrate tended to increase further under the combined effects of the thermal conductivity of the component itself and the convective heat transfer between the component and the external environment. With the increase of powder deposition temperature, both the lateral maximum residual tensile stress and the lateral maximum residual compressive stress of the component increased. With the increase of powder deposition temperature, the longitudinal maximum residual compressive stress of the component increased and the longitudinal maximum residual tensile stress decreased.

A finite element analysis-computational fluid dynamics coupled analysis on thermal-mechanical fatigue of cylinder head of a turbo-charged diesel engine

A finite element analysis-computational fluid dynamics coupled analysis on the thermo-mechanical fatigue of cylinder head of a turbo-charged diesel engine was performed, and the complete simulation process is illustrated in this paper. In-cylinder combustion analysis and water jacket coolant flow analysis were conducted to provide heat transfer boundary conditions to the temperature field calculation of the cylinder head. Comparing with the conventional finite element analysis of cylinder head by which the heat transfer boundary conditions of the combustion and coolant sides are estimated, the present method coupled the three-dimensional combustion computational fluid dynamics and coolant computational fluid dynamics with the finite element analysis. Both computational fluid dynamics and finite element analysis obtain more accurate boundary conditions on their interface from each other, and thus, the present method improves accuracy of thermo-mechanical fatigue prediction. Based on the measured material performance parameters such as stress–strain curve under different temperatures and E–N curve, creep, and oxidation data material performance, the cylinder head–gasket–cylinder block finite element transient stress–strain field was calculated using ABAQUS. The thermo-mechanical fatigue analysis of cylinder head submodel was performed by using FEMFAT software that is based on the Sehitoglu model to predict the thermo-mechanical fatigue life of cylinder head. By comparing the measured and predicted temperatures of cylinder head, the temperature results showed a good agreement, and the error is less than 10%.

Research on Performance and Emission of Ic Engine using Porous Medium Cylinder Head

At present IC engines are experiencing with partial ignition and irregular temperature circulation inside the engine cylinder due to improper mixing of air and fuel mixture. Due to this effect, NOx , CO and Unburned hydro carbons will be released into the atmosphere. Excessive soot formation also takes place in the IC engine. To perform the homogeneous combustion inside the engine cylinder the new Porous Medium concept has been proposed. Porous Medium engine concept is mainly for reducing the emissions and improving the performance characteristics of the IC engine. Gun Metal Porous Medium has been introduced at the top of the Kirloskar 5BHP diesel engine cylinder head. When compared to conventional engine, reduction of total fuel consumption quantity up to 13%, Specific fuel consumption quantity up to 12%, increment in Brake thermal efficiency up to 12% and Indicated thermal efficiency up to 6% are obtained during part load operations. When compared to conventional engine, Mechanical efficiency has been increased up to 8%, NOx level gets reduced up to 53% and CO2 level gets decreased up to 46% from no load to full load operations.

DIESEL ENGINE FAULT DIAGNOSIS BASED ON DT-CWPT AND RBF NEURAL NETWORK

Aiming at the large amount of vibration signal and data redundancy on the cylinder head of diesel engine, this paper uses DT-CWPT to process the acquired signal, including data denoising processing and feature vector extraction. After the wavelet decomposition is collected, the dimension of the signal is reduced, and the excess signal components can be filtered out, the fault features are highlighted, and the information contained in the signal is not damaged, and the accuracy of the fault diagnosis is improved; the RBF neural network has an excellent mode. Recognition performance, relative to the neural network has a rapid diagnosis ability; particle swarm optimization algorithm to optimize the RBF neural network basis function, can improve the diagnostic speed of RBF neural network. Finally, the research is applied to the actual experiment to verify the superiority of the method.

A digital twin-based approach for dynamic clamping and positioning of the flexible tooling system

The process preparation time for complex parts accounts for more than 20% of the parts manufacturing cycle, which is the main factor restricting the improvement of production efficiency. To shorten the process preparation time, we propose an approach for dynamic clamping and positioning of flexible tooling system based on the digital twin technology. Three core technologies embodied in the proposed method are illustrated in details as follows: (1) real-time acquisition, organization, and management of the geometry data of the machining parts; (2) digital twin data driven decision of the clamping forces and positioning position; (3) construction of the digital twin-based flexible tooling system. To elaborate how to apply the proposed approach to the reality, we present detailed implementation process of the proposed approach in the diesel engine cylinder head production line. Meanwhile, the future work to completely fulfill digital twin-based smart flexible tooling system is discussed.