The present experimental study proposes an alternative for diagnostic methods and quality control in cylinder head defectology. The composition of the material is characterized by spectrometry, ...obtaining an approximation of aluminum 2117. For the detection of defectologies, non-destructive tests (NDT) are carried out, applicable to cylinder heads such as: visual inspection (VT) under conditions of standard EN 13018, penetrating inks (PT) visible according to ASTM E 165-02 and others not yet included in the vehicle fleet.; infrared thermography (IRT) with equipment specifications under ISO 18434 - 1, ultrasound (UT) based on standard EN 583 for the use of the equipment and Eddy currents (ECT) conforming standard ISO 15548, the analysis is carried out on the flat surface of the cylinder head, combustion chamber, valve seats and intake - exhaust ports, the different defects found are: cracks, fissures, discontinuities and pitting, showing longitudinal dimensions from 0,8 mm. To determine the reliability of results, an analogy is made of the tests mentioned in the same defect, the method with the greatest scope is Eddy currents as it has more inspection coverage with respect to the remaining tests; the simulation of computer-aided engineering CAE of the defect is performed, applying an AC magnetic analysis to identify the flux density, current density and visualize how the Eddy currents act in the cylinder head. After this research, artificial intelligence will be used as a complementary diagnosis, to predict defectologies not perceived by the human eye and to obtain a better analysis of defectologies in cylinder heads.
Reverse design based on slicing method Luo, Tong; Lian, Zhang-hua; Yu, Hao ...
Journal of the Brazilian Society of Mechanical Sciences and Engineering,
12/2019, Volume:
41, Issue:
12
Journal Article
In order to resolve and improve the reverse design of the inner chamber parts, the airflow model of an engine’s cylinder head was taken as research object, and the reverse design methods used for ...complex inner chamber parts were explored based on slicing method. According to the structural and functional features of airflow model of the cylinder head, the technologies of measure and treatment for the point cloud data were studied, and the technologies of fitting the contour curve based on different sections and features, reconstructing surface based on different segments and features for the airflow were proposed. It can be seen from the error analyses and engineering practical experiences that the quality and accuracy of the reconstructed model can be ensured and improved with this reverse design method. It has reference significance for the design and reverse design of similar inner chamber parts.
Thermal fatigue properties of several scaled cylinder head specimens (SCHS) are evaluated. The plastic deformation of the intake holes (ITH) and exhaust holes (EXH) during the experiment was ...recorded. The results show that the plastic deformation mainly occurred in the early stage of the thermal shock. The increment of the plastic deformation decreases with an increase in the number of fatigue test cycles. Additionally, the thermal stress distribution indicates that the nose bridges of the SCHS suffers greater thermal stresses than other areas. In particular, nose bridges between the ITH and EXH suffer the largest thermal stress than the other nose bridges. Furthermore, nose bridges with lower thermal stress, reduced initial surface roughness and deformation have better performance in terms of thermal fatigue life. This study provides a basis for exploring the thermal fatigue failure mechanism of cylinder head and is beneficial for the cylinder head design.
We work on improving the technology for predicting the gas seal performance of head gasket. Among them, I would like to judge the difference in the engine evaluation results with different rubber ...materials. In order to consider deterioration during engine evaluation, we focused on the reduction of rubber thickness. We have developed a new unit evaluation method to quantitatively judge the reduction of rubber thickness. The evaluation conditions are based on analysis results that simulate engine evaluations. New prediction technology that combines these showed the same results as the engine evaluation.
Leakage is always a concern in the interface between the cylinder block and the head. Nowadays, sealing of this interface is almost exclusively achieved by multi-layer steel head gaskets. However, it ...is not only the gasket's quality that is responsible for perfect sealing. An equally important role is played by the surface topography of the mating surfaces. The top surface of the cylinder block and the bottom surface of the cylinder head are machined by face-milling and present periodic tool marks features. Based on the surface topography measured by high definition metrology, this paper presents a novel sealing analysis method to evaluate the sealing performance of the critical topography region around the combustion chambers. The method consists of three modules: tool paths or channels reconstruction, sealing region segmentation based on channels' directions, and sealing analysis on sealing regions with different channel directions. An engineering case demonstrates the sealing analysis procedures and verifies the effectiveness of the sealing analysis method. The analysis of 12 ring-shaped sealing regions found that channels' directions do have a significant impact on surfaces' sealing properties. Circumferential channels or paths are advantageous for surface sealing, while radial channels are prone to leakage.
•A sealing analysis framework is proposed for face-milled surfaces' topography considering the cutting tool trajectories.•An ellipsoid structuring element is proposed to simulate the contact behavior of gaskets by morphological closings.•The least contact area required for effective sealing is found by a searching algorithm.•Circumferential channels or paths are advantageous for surface sealing, while radial channels are prone to leakage.
Due to the complex structure of the large cylinder head, it is prone to produce uncontrolled casting defects and uneven microstructure distribution. In order to predict the porosity defects and ...secondary dendrite arm spacing (SDAS) in the as-cast cylinder head, the low pressure casting process of aluminum alloy cylinder head was simulated. Moreover, to verify the accuracy of the simulation results, microscopic observations were performed, in which the simulation results are reasonably matching with that of experiment results. Both simulation and experiment results demonstrate that porosity defects mainly exist in thick walls as well as thick-thin wall junctions. In addition, the top plate presents the finest microstructure, while the microstructure of the force wall is the coarsest. Additionally, the correlation of casting parameters with porosity defects and microstructure was discussed, suggesting that increasing the cooling rate could partially reduce porosity defects. Furthermore, the finding that decreasing the cooling rate can reduce the SDAS of the casting, resulting in a dense microstructure, was drawn. Besides, it has been concluded that regular shapes and thin walls are advantageous for both reducing porosity defects and obtaining uniform microstructures. This provides an effective approach for predicting the casting defects and microstructure of large complex structural castings through numerical simulation. In addition, a quantitative understanding of the casting parameters, complex structure-microstructure relationship for cast aluminum alloys will allow better determination of process parameters based on microstructure and properties requirements of complex components.
The European Commission's ambitious plan to reduce CO2 emissions has a significant impact on the global automotive industry. Recent development of new diesel and petrol engines with direct injection ...is aimed at improving fuel efficiency while maintaining (or enhancing) engine performance. This naturally also increases the demands on the properties of the most stressed engine components (e.g., cylinder heads, engine blocks, pistons), which leads to the development of new materials. Presented work analysed the effect of different mold temperatures (60; 120; 180 °C) on mechanical, physical properties and microstructure of AlSi5Cu2Mg aluminium alloy. This alloy is currently being used for the production of cylinder head castings. The results showed that the changing mold temperature had an effect on mechanical properties (ultimate tensile strength and Young modulus values). SEM with EDX analysis of intermetallic phases revealed there were no size and morphology changes of Cu, Mg and Fe intermetallic phases when the mold temperature changed. No significant effect of different mold temperature on physical properties (thermal and electrical conductivity) and fracture mechanism occurred during experiment. Optimal combination of mechanical and physical properties of AlSi5Cu2Mg alloy was achieved using a permanent mold with temperature ranging from 120 to 180 °C.
•Tensile strength and S-N curve of the aluminum alloy 242.0 were determined.•Numerical thermomechanical analysis of the cylinder assembly was performed.•The cylinder assembly locations with the ...highest stress values were determined.•An integrity assessment of the cylinder assembly has been carried out.•The cylinder head failure is due to material fatigue caused by presence of porosity.•The further research will be related to the cylinder head with a crack analysis.
Failures of aircraft piston engine components are a common occurrence in practice. During operation, cylinder heads are components that are exposed to multiaxial thermomechanical loads leading to fatigue. Therefore, predicting the lifetime of the cylinder heads exposed to such loads is one of the most important tasks to ensure engine quality, durability and safety. This paper is the continuation of a comprehensive research of the Lycoming IO-360-B1F aircraft engine cylinder head failure. The failure of this type has already occurred during flight and about 50 failures like this have been registered from around the world, some of them with a fatal outcome and therefore require detailed research. This research includes the numerical stress and fatigue analysis of the cylinder assembly exposed to high cycle mechanical and thermal loads that failed due to a crack appearance on the cylinder head. A 3D cylinder assembly model was created. The locations with the highest stress values, both mechanical and thermal, were determined using numerical analysis. Also, the lifetime of the cylinder assembly has been determined, i.e. an integrity assessment has been carried out which will contribute to the consideration of the crack appearance problem. Defining the coupled thermomechanical load of the cylinder assembly in the numerical analysis gives special significance to this paper. The results obtained will serve to analyze the crack propagation in the cylinder head which is going to be the subject of further research.
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