Part Of Cylinder Research Articles

Improvement of dimensional accuracy based on multistage single point incremental forming of a straight wall cylinder part

Multistage forming is usually adopted to form those parts with steep angle or straight wall during single point incremental forming. In order to study multistage single point incremental forming further, based on an experiment method and a mathematic analysis method, straight wall cylinders are fabricated with different materials and different heights to investigate dimensional accuracy of specimens obtained. Three kinds of materials including 1060 aluminum, Q235 steel and DC04 steel are selected to deform specimens with four-stage single point incremental forming. The mathematic model of dimensional error is proposed to predict the sinking defect according to the law of energy conservation. In addition to this, the strain strength coefficient (K) and the axial feed rate (v 1) are studied in detail for the largest deviation of specimens. Experiment results demonstrate that the mathematic model is feasible and an optimal v 1 obtained effectively improves the dimensional accuracy of specimens.

Effect of Roller Path on the Formability of Drawing Spinning

Drawing spinning is widely used for the manufacture of cylinder parts from disk blank. And the roller path can affect its formability strongly. But how does the effect mechanism work is rarely revealed. The plastic of the metal is one key factor for the failure of spinning such as fracture and wrinkling. In order to reveal the relationship between the roller path and the formability, two working conditions with one-pass (Scheme I) and multi-pass (Scheme II) roller path are proposed. And the comparative analysis of their metal flow evolution is carried out by the finite element method. It is found that one-pass roller path isn't conducive to putting down the flange gradually. And this will bring larger deformation resistance to cause cylinder wall fracture and reduce the formability of drawing spinning.

Temperature field simulations during selective laser melting process based on fully threaded tree

Selective laser melting (SLM) is a promising technique for additive manufacturing. During SLM of metallic powder, the temperature field and thermal history are important to understand physical phenomena involved. The purpose of this study is to simulate the temperature field during the SLM process of a hollow cylinder shape part based on a fully threaded tree (FTT) technique, and to analyze the temperature variation with time in different regions of the part. A revised model for temperature field simulation in the SLM process was employed, which includes the transition of powder-to-dense sub-model and a moving volumetric Gaussian distribution heat source sub-model. The FTT technique is then adopted as an adaptive mesh strategy in the simulation. The simulation result shows that during the SLM process of cylinder part, the temperature of inner powder bed is obviously higher than external one. The temperature at the internal of the molten pool is also higher than external, which may lead to differences in microstructures and other properties between the two regions.

Particle Image Velocimetry measurement of flow around an inclined square cylinder

This study investigated flow around an inclined square cylinder by using Particle Image Velocimetry technique in a wind tunnel. Two types of inclinations, i.e. forward inclination and backward inclination, were tested. Two inclination angles, i.e. α = 15° and 30° were tested for each type of inclinations. It was found that the forward inclination enhances the downwash that originally appears behind the upper part of the vertical cylinder, whereas weakens the upwash that is exhibited behind the base part of the vertical cylinder. When the forward inclination angle is large enough, the downwash is enhanced to a downward axial flow, whereas the upwash is completely suppressed. On the contrary, the backward inclination depresses the downwash, while enlarges the upwash. As the backward inclination angle increases, the upwash evolves into an upward axial flow.

Modular construction mechanics of a European pressurized reactor steel containment liner

A European pressurized reactor (EPR) steel containment liner structure is comprised of the cylinder part and the dome part. An introduction of the steel liner structure is presented, followed by studies on the key mechanical features of the construction process using a refined finite element method. The steel liner was divided into several modules and then assembled during construction. Firstly, the equipment structure used to hoist the liner module was optimized, the lifting lug was analyzed using a multi-scale finite element model; the wind speed limit during lifting was also studied. Subsequently, the effect of internal forces during assembly between the liner modules, the lateral pressure of fresh concrete, the non-uniform temperature load, and the wind load on the cylinder module was analyzed. According to the time-varying structural performance during continuous concrete pouring and the hardening construction, an “overlapping element and birth-death element” technique was adopted to analyze the deformation and stress of the long-span steel dome liner. In addition, the stability-bearing capacities of the dome structure during construction were also studied, which took into consideration the effect of the initial geometrical imperfections and the elasto-plasticity of the material. This study presents a reference in terms of the mechanics of the construction scheme and the safety of such a type of structure.

Forward acoustic scattering analysis from solid objects immersed in the water

Forward acoustic scattering of an immersed solid LINE (cylinder bounded by hemispherical endcaps) in water is investigated in our study. The object is made of stainless steel and its L/2a ratio is equal to 2 (L: Length of the cylinder part and a: the radius is equal to 60 mm). An impulse measurement method is used in the experimentation. Most of results are obtained experimentally, in bistatic configuration. Mobile receiver transducer is located in a distinct position from the emitter. The polar diagram patterns of the scattered pressure shows an important amplitude of pressure in the shadow side of this object. Analysis of this phenomenon is based on theoretical and experimental results obtained for a sphere with the help of elasticity theory. Moreover, this study relies on the grey-level representation of the angular position of the receiver in function of recorded time signals. Thus on forward acoustic time signals, it is possible to identify echoes due to propagation paths of waves on this object.

Noise source separation of diesel engine by combining binaural sound localization method and blind source separation method

In order to separate and identify the combustion noise and the piston slap noise of a diesel engine, a noise source separation and identification method that combines a binaural sound localization method and blind source separation method is proposed. During a diesel engine noise and vibration test, because a diesel engine has many complex noise sources, a lead covering method was carried out on a diesel engine to isolate other interference noise from the No. 1–5 cylinders. Only the No. 6 cylinder parts were left bare. Two microphones that simulated the human ears were utilized to measure the radiated noise signals 1m away from the diesel engine. First, a binaural sound localization method was adopted to separate the noise sources that are in different places. Then, for noise sources that are in the same place, a blind source separation method is utilized to further separate and identify the noise sources. Finally, a coherence function method, continuous wavelet time-frequency analysis method, and prior knowledge of the diesel engine are combined to further identify the separation results. The results show that the proposed method can effectively separate and identify the combustion noise and the piston slap noise of a diesel engine. The frequency of the combustion noise and the piston slap noise are respectively concentrated at 4350Hz and 1988Hz. Compared with the blind source separation method, the proposed method has superior separation and identification effects, and the separation results have fewer interference components from other noise.

Techniques for measuring and compensating for servo mismatch in machine tools using a laser tracker

Servo mismatch, which affects positioning accuracy in computer numerical control (CNC) machine tools, is an important source of error. Dynamic measurements of simultaneous movements in two axes are essential in determining servo mismatch. A circular test using a double ball-bar (DBB) is used commonly to assess such errors. However, servo-mismatch measurements of some machine tools, such as miniaturized machine tools, remain difficult due to structural restrictions of the measuring devices. In this study, a technique for servo-mismatch measurement via a bi-directional circular test using a laser tracker is described. The laser tracker is easy to set up experimentally and has fewer measuring range restrictions than other measuring devices. In order to ignore the effects of quasi-static errors, a bi-directional circular test is conducted using the laser tracker. Additionally, a compensation procedure, with a proportional equation, is proposed. The validity of the technique described was confirmed by comparison with the DBB result. In a machining test after servo-mismatch compensation, by adjusting the position loop gain, the roundness of a cylinder part was improved by ∼47.9%.

Plasma diagnostic of cup-like magnetron source for transparent conductive oxide thin films

Novel designs of magnetron sputtering sources provide desired control over plasma parameters for efficient use of mass and energy transport during the deposition of thin films. Here, a cup-like magnetron source, comprising a base and a cylinder part, is developed and diagnosed for deposition of transparent conductive Al doped ZnO thin films. The coupling of the base or/and cylinder parts, applied power and working pressure are systematically varied and consequent effects on the plasma density, electron temperature, and substrate temperature are studied. The sensitive optical emission and absorption spectroscopic results of plasmas reveal that base source mainly delivers the Zn ionic species whereas coupling of cylinder source induces higher ion-electron recombination and lowering the substrate temperature. The present source is capable of producing Al doped ZnO thin films with resistivity in the range of 5 × 10−2 Ωcm to 12.1 Ωcm and process throughput close to 40 nm/min under conditions of plasma induced substrate temperature ≤60 °C. The obtained values have promising applications for flexible electronics.

ПОВЫШЕНИе УСТОЙЧИВОСТИ К ДЕСТАБИЛИЗИРУЮЩИМ ФАКТОРАМ ЭНЕРГЕТИЧЕСКОЙ УСТАНОВКИ ПРОМЫСЛОВОГО СУДНА

The task of developing methods and tools for the study of stability for parallel operation of two or more diesel and the shaft generator sets as a part of an autonomous electrical power system of the fishing vessel is considered. The use of such devices is a promising and demanded, but difficult to implement due to the high dependence of the frequency of the current generated by such units on the temperature and the quality of lubricating oils, advance angle of fuel supply, the depreciation of the fuel equipment, the influence of depreciation of cylinder piston group and parts of the crank mechanism, the load, the fuel properties and the external environment. The method of increasing the stabilization of processes in the units of the ship power plants and providing their rating data in the conditions of availability of the destabilizing operational factors is offered. The method is based on the compensation of influence of the destabilizing operational factors on dynamic characteristics of transition processes on the frequency of ship power plant units. The modeling results are presented in the example of implementation of described approach. The scheme of the regulator of the sliding mode of the adaptive system of automatic control with the frequency of rotation of a bent shaft of diesel allowing to study the processes of fluctuations of its speed and to develop the principles of its effective management was developed. For its synthesis the new mathematical description of dynamics of diesel which brings the generator into rotation was developed. This allows not only to provide the work of diesel and the shaft generators units, but also, as a result, to exercise effective management of electric power parameters in autonomous electric power industry, to develop means and methods of providing the required indicators of quality of the electric power produced by the main and auxiliary power units.

Laminar natural convection heat transfer from a pair of attached horizontal cylinders set in a vertical array

The natural convection heat transfer from two attached cylinders set in a vertical array in air has been studied numerically for the Rayleigh number varying from 10 to 105. The comprehensive results consisted of streamlines and isothermal contours, temperature and velocity profiles, as well as local and average Nusselt number are presented with different Rayleigh numbers. They show that the heat transfer for both cylinders is degraded relative to that for a single cylinder owing to the interactions of their plumes. That trend mainly stems from the greater effects of the interaction on the upper part of the lower cylinder and the bottom surface of the upper cylinder. By contrast, it has little influence on the bottom surface of the lower cylinder and top region of the upper cylinder thereby leading to the similar results to that for a single cylinder there, but with a small noticeable difference. Also, their stronger interactions lead to the heat transfer rate of the upper cylinder reduced by 16–53% relative to that at S/D=2. What's more, the correlating equations for individual cylinder and the whole array have been proposed respectively, which provide an accurate prediction for the engineering calculations applying the present configuration.

Radiation Noise Separation of Internal Combustion Engine Based on Gammatone-RobustICA Method

In the internal combustion engine noise source separation process, the combustion noise and the piston slap noise are found to be seriously aliased in time-frequency domain. It is difficult to accurately separate them. Therefore, the noise source separation method which is based on Gammatone filter bank and robust independent component analysis (RobustICA) is proposed. The 6-cylinder internal combustion engine vibration and noise test are carried out in a semianechoic chamber. The lead covering method is adopted to isolate the interference noise from numbers 1 to 5 cylinder parts, with only the number 6 cylinder parts left bare. Firstly, many mode components of the measured near-field radiated noise signals are extracted through the designed Gammatone filter bank. Then, the RobustICA algorithm is utilised to extract the independent components. Finally, the spectrum analysis, the continuous wavelet time-frequency analysis, the correlation function method, and the drag test are employed to further identify the separation results. The research results show that the frequency of the combustion noise and the piston slap noise are, respectively, concentrated at 4025 Hz and 1725 Hz. Compared with the EWT-RobustICA method, the separation results obtained by the Gammatone-RobustICA method have very fewer interference components.

Formability of aluminum alloy thin-walled cylinder parts by servo hot stamping

Abstract In order to meet the huge demands of automotive lightweight, the application of aluminum alloy sheets in the automotive parts has gradually increased in recent years. Aluminum alloy sheets, however, usually have low ductility at room temperature, which results in the poor formability of automotive parts by using traditional forming processes, especially for those with large size, thin wall and complex shapes. In this paper, the formability of aluminum alloy thin-walled cylinder parts by a novel process, i.e., servo hot stamping was discussed. First, a robust finite element model of thin-walled cylinder part made in aluminum alloy 7075 sheet hot stamping was established based on finite element simulation software ABAQUS. The servo motion mode was then put forward and a suitable forming speed area ranging from the motion curve 2 to the motion curve 4 were demined. Finally, the effect law and mechanism of servo motion on the formability of such thin-walled cylinder parts were revealed by analyzing plastic strain, thickness and temperature distributions. The results have academic value and practical significance for the forming of aluminum alloy parts.

Thermal Analysis of cylinder block with fins for different materials using ANSYS

In internal combustion engines cylinder part is the heart of the engine and this cylinder block forms the walls of a combustion chamber where air fuel mixture burns. Due to this continues combustion process the cylinder walls subjected combustion zone and heat transfer takes place through the cylinder material. If the heat is not dissipated properly then it causes to development of detonation and it finally decreases the working efficiency of the engine, hence the heat removal rate from the cylinder is one of the important and interesting task. Mostly the heat transfer rate through the material is depends on the thermal conductivity of the material. Hence in this paper an attempt has been made to find out the thermal analysis of cylinder block with fins for different materials by using ANSYS, and the results has been analyzed to find out the best material that gives the better heat transfer rate and consists of light weight.

A Lightweight Structure Redesign Method Based on Selective Laser Melting

The purpose of this paper is to present a new design method of lightweight parts fabricated by selective laser melting (SLM) based on the “Skin-Frame” and to explore the influence of fabrication defects on SLM parts with different sizes. Some standard lattice parts were designed according to the Chinese GB/T 1452-2005 standard and manufactured by SLM. Then these samples were tested in an MTS Insight 30 compression testing machine to study the trends of the yield process with different structure sizes. A set of standard cylinder samples were also designed according to the Chinese GB/T 228-2010 standard. These samples, which were made of iron-nickel alloy (IN718), were also processed by SLM, and then tested in the universal material testing machine INSTRON 1346 to obtain their tensile strength. Furthermore, a lightweight redesigned method was researched. Then some common parts such as a stopper and connecting plate were redesigned using this method. These redesigned parts were fabricated and some application tests have already been performed. The compression testing results show that when the minimum structure size is larger than 1.5 mm, the mechanical characteristics will hardly be affected by process defects. The cylinder parts were fractured by the universal material testing machine at about 1069.6 MPa. These redesigned parts worked well in application tests, with both the weight and fabrication time of these parts reduced more than 20%.

Heat Transfer in Diesel and Partially Premixed Combustion Engines; A Computational Fluid Dynamics Study

ABSTRACTThis article presents findings from a Computational Fluid Dynamics (CFD) study performed on the heat transfer characteristics of diesel and partially-premixed combustion (PPC) engines. The study is confined to the combustion bowl, where numerical simulations have been performed on a part of the engine cycle, namely the compression, combustion, and expansion phases. Three engine geometries were simulated and after validating the results with experimental data, parameter variations were carried out, in order to estimate their effects on the heat transfer, engine performance, and emission levels. The work was performed using a commercial CFD tool, with which only a part of the engine cylinder was modeled, the enclosure of one spray. The results highlight some important characteristic differences between the conventional diesel combustion and the low-temperature combustion scheme PPC. The reduced in-cylinder temperatures for the PPC case lead to a reduced production of NOx and soot emissions, without compromising the engine performance, only a small penalty in the increased intake air pressure is found. The importance of an appropriate injection strategy was also highlighted, as the presence of a pilot injection during the compression stroke enhanced the temperature stratification in a PPC engine. This leads to reduced heat losses and improved engine efficiency. Finally, the shape of the combustion bowl was shown to have significant effects on both heat losses as well as emission levels.

Noise source identification of diesel engine based on variational mode decomposition and robust independent component analysis

Through separating and identifying the noise sources of diesel engine, each independent noise obtained can be used as reference for the noise reduction, condition monitoring and fault diagnosis. In the noise source identification of diesel engine, the combustion noise and the piston slap noise are found to be overlapped in time domain and frequency domain. So it is intricate to accurately separate them. Therefore, the noise source identification method which is based on variational mode decomposition (VMD), robust independent component analysis (RobustICA) and continuous wavelet transform (CWT) is proposed. In the test, a 6-cylinder diesel engine was tested in a semi-anechoic chamber. The lead wrapped method was adopted to wrap No. 1–5 cylinders so as to isolate the interference noises, only the No. 6 cylinder part was bared. The single channel noise signal of cylinder head was measured. Then the variational mode decomposition algorithm is utilized to decompose the noise signal into several variational mode components. The RobustICA algorithm is adopted to extract the independent components. Finally, the continuous wavelet transform and the prior knowledge of diesel engine are applied to further identify the separated results. The results show that by using the proposed method to separate and identify the radiation noise of the cylinder head of the diesel engine, the independent components obtained are respectively the combustion noise and the piston slap noise. Comparing with the EEMD-RobustICA-CWT method, each independent noises obtained through the proposed method are more accurate and pure with less other interference noises.

Effect of Melt Rate on Surface Quality and Solidification Structure of Mn18Cr18N Hollow Ingot during Electroslag Remelting Process

A new method for manufacturing Mn18Cr18N steel applied to retaining ring has been developed based on hollow ESR ingot. The ESR hollow ingot not only keep away from upsetting and punching, provide hollow billet for forging directly, but also meet the need of high quality of the raw material. ESR hollow ingot of Mn18Cr18N steel has been produced successfully in our lab. Melt rate is the most important technological parameter of electroslag remelting (ESR) process, which influences ingot quality and production efficiency. To further investigate the influence of surface quality on melt rate, the experimental results comparing to the simulations results have been implemented in this paper. A mathematical model to describe the temperature distribution and the solidification structure of ESR hollow ingot of Mn18Cr18N steel has been established. The change of metal pool profile, pool cylinder part height, and grain growth angles during hollow ESR process are calculated based on the coupled technology of CAFE method and the moving boundary method, which are consistent with the experimental results. The experiment of hollow ESR Mn18Cr18N steel at the most suitable melt rate obtained by numerical simulation results has been carried out to reveal the law of cylinder part height of metal pool changing with the withdrawal speed. The optimal technological parameters applied in the experiment of hollow ESR process can reasonably control the surface quality of Mn18Cr18N hollow ingot.

An extended machining error propagation network model for small-batch machining process control of aircraft landing gear parts

The complex structure and small-batch nature of aircraft landing gear parts lead to complex machining error propagation mechanism and manufacturing complexity. An Extended Machining Error Propagation Network model is presented to quantitatively analyze the complex coupling relationship in the Small-batch Multistage Machining Process of aircraft landing gear parts. Firstly, to depict the coupling relationship quantitatively, the Quality Features are defined to describe the machining precision information of Machining Form Features, and the State Elements are defined to describe the running state information of Machining Elements. Then, Machining Form Features, Machining Elements, Quality Features, and State Elements are identified as different network nodes, and the coupling relationships (such as evolving, locating, machining, and attribute) among these nodes are mapped into network edges. Based on the in-process measuring and sensing data of each machining stage, the topological and physical metrics of the network are explored to analyze the error propagation characteristics. Finally, the machining process of an outer cylinder part from aircraft landing gear is studied to verify the proposed methods.

Modelling gastric evacuation in gadoids feeding on crustaceans.

A mechanistic, prey surface-dependent model was expanded to describe the course and rate of gastric evacuation in predatory fishes feeding on crustacean prey with robust exoskeletons. This was accomplished by adding a layer of higher resistance to the digestive processes outside the inner softer parts of a prey cylinder abstraction and splitting up the prey evacuation into two stages: an initial stage where the exoskeleton is cracked and a second where the prey remains are digested and evacuated. The model was parameterized for crustaceans with different levels of armour fed to Atlantic cod Gadus morhua or whiting Merlangius merlangus and recovered from the stomachs at different post-prandial times. The prey species were krill Meganyctiphanes norvegica; shrimps and prawns Crangon crangon, Pandalus borealis, Pandalus montagui and Eualus macilentus; crabs Liocarcinus depurator and Chionoecetes opilio. In accordance with the apparent intraspecific isometric relationship between exoskeleton mass and total body mass, the model described stage duration and rate of evacuation of the crustacean prey independently of meal and prey sizes. The duration of the first stage increased (0-33 h) and the evacuation rate of both stages decreased (by a half) with increasing level of the crustacean armament in terms of chitin and ash. A common, interspecific parameterization of the model within each of the categories krill, shrimp and crab can probably be used if the contents of chitin and ash are similar among prey species per prey category. The model offers a simple way for estimating evacuation rates from stomach content data in order to obtain food consumption rates of wild fishes, provided that information about digestion stage of crustacean prey is available.