Applied Mechanics and Materials Vols. 713-715

Abstract: Based on ArcGIS,Multi-heat sources and multi-loops complex heating network is Modeled and simulated ,and a functional method is put forward, by using Geodatabase data model,it can creat relating matrix and basic loop matrix of heat network quickly,and calculate Hydraulic Regime of heating Network with the Basic Circuit.When pipe-bursting accident occur in heating Network,along with changes in the logical network model.also the entire calculation model is changed.This method is applied to the Study of Valve-shut off scheme after tube-burst accident ,the heating Influence of the accident can be quantitative analyzed , also the degree of influence is compared when tube-burst accident happen at different place.

Abstract: To research the lubricating property of line contact elastohydrodynamic lubrication under the working conditions of overloading velocity jump, based on the optic elastohydrodynamic experimental apparatus developed by the research group, an measuring equipment applicable to the oil film thickness and shape under the condition of overloading velocity jump is designed and developed. This testbed is mainly composed of glass block reciprocating motion system, ball or roller rotary rolling system, loading system, speed regulating system, light source system and image acquisition system. The motion part replaces the slider-crank mechanism with kad-screw mechanism and is driven by stepper motor, so as to realize the different working conditions of velocity jump. The developed platform was adopted to carry out the velocity jump line contact elastohydrodynamic lubrication test by the driving of the stepping motor, investigating the influence of line contact friction pair on the lubricating oil film at the moment of acceleration under the overloading working condition.

Abstract: The two problems restrict the development of directly buried pipeline installation without compensation technology in the heating engineering.Therefore, the intensity of elbow itself is analyzed to optimize the elbow .A new model of elbow is provided .This paper uses ANSYS finite element analysis software to establish a new type of elbow model.We compare and analyze the stress of ordinary elbow which add block and do not add block ; two different types which both have the same wall thickness and new type elbow which have 5 different wall thickness for each elbow.The results show that:(1) the new type elbow can reduce the stress greatly;(2) with the increasing diameter of elbow, the stress of inner elbow decreases gradually. Therefore, this new type of elbow can truly realize non-compensating installation in heating system.

Abstract: CNC machine tools tend to build their coordinate systems according to the categories of returning reference points. Due to their detecting structures and principles, four distinct styles of reference point returning come into being, that is, Reference Point Establishment based on Incremental Encoder and Mechanical Block, Datum-point style Returning Reference point, Reference Point Returning with Incremental Encoder and no Mechanical Block, Percussion Reference Point Returning based on Absolute Encoder. In this paper, the author tries to probe into the basic requirement, working process and design requirement of the four styles.

Abstract: The randomness of wind power and the nonstationarity of gearbox vibration signals greatly increased the difficulty of wind turbine gearbox faults feature diagnosis. Studies proved that Hilbert-Huang transform (HHT) has a satisfying performance when it be used to analyze nonlinear and non-stationary signals, but two troublesome problems in application of HHT are end effect problem and false intrinsic mode functions (IMFs). An improved solution method based on adaptive waveform matching endpoint extension is proposed to solve end effect problem. Meanwhile, an improved energy conservation method is proposed to eliminate false IMFs. Tests prove that improved HHT can greatly improve the accuracy of wind turbine gearbox faults diagnosis and with a balance efficiency.

Abstract: A CAE analysis on the precision forging of big semimonocoque of vehicle axle was conducted based on DEFORM-3D software. It discussed effects of forging billet size and shape on the forging property and effect of forging shape on the flow law of metal materials, and analyzed equivalent stress, strain distribution and load-stroke curve during the forging process. Research results are used to optimize mold structure and technological parameters. Precision forging of big semimonocoque was verified valid by practical production.

Abstract: The new typology of marine facilities deals with the problem of offshore oil and gas fields’ infrastructure usage after their elimination. The influence of climate on offshore structures and the authorities’ requirements in the matter of natural environment protection create huge costs for oil and gas companies, if the abandoned platform will be at sea. The concept of oil platform reconstruction with the change of functionhas allowedto create theoretical model of offshore structure and to identify the most relevant functions for the reconstructed objects. It has led to the following basic groups of architectural typology.

Abstract: Producing good surface integrity is one of the main challenges of the machining industry. The increase of the utilization of minimum quantity lubrication (MQL) in order to reduce the amount of lubrication induced a lack of understanding of the physics behind the residual stress generation. Residual stress in the machined surface and subsurface is affected by materials, machining conditions, and tool geometry. These residual stresses could affect the service qualify and component life significantly. Residual stress can be determined by empirical or numerical experiments for selected configurations, even if both are expensive procedures. This paper presents a hybrid neural network that is trained using Simulated Annealing (SA) and Levenberg-Marquardt Algorithm (LM) in order to predict the values of residual stresses in cutting and radial direction after the MQL face turning process accurately. First, SA is used to train the weight and bias values of the ANN after which LM is used to fine tune the values trained by SA. Then, based on the predictions, an optimization procedure, using Genetic Algorithm (GA), is applied in order to find the best cutting conditions. At each generation, GA suggests a population of inputs that are then sent to the trained ANN in order to predict the residual stresses. The objective is to find the optimal inputs that minimize the tensile stress on the machined surface.

Abstract: Constraints and a driving were imposed to the three-dimensional model of slider-crank mechanism of the Mechatronics Fitness and Entertainment Machine modeled and assembled by UniGraphics 6.0 for dynamic simulation analysis in order to get velocity-time curve and acceleration-time curve. Usability of model was verified by comparing to the result of theoretical analysis of slider-crank mechanism. Finally, it was achieved to design the virtual prototype.

Abstract: Tool nose radius is an important geometrical parameter in the design of the tool. Due to its direct contact with the workpiece surface it have significant effect not only on the resulting surface quality but also on the tool life. Use of an end mill without nose radius can easily blend during machining due to a lot of stresses acting on the edge of the tool while the large nose radius end mill can increase the strength and rigidity of the tool but can also contribute in increasing the friction between the tool and the workpiece. Therefore careful selection of tool nose radius is important and especially important for Polycrystalline Diamond, PCD insert as this tool material has recently shown great success in terms of tool life, surface roughness and productivity over coated and uncoated carbide tools in high speed end milling of titanium alloy Ti-6Al-4V and with the use of correct tool geometry it can be further helpful in increasing tool life and surface quality. This study therefore investigates the effect of various nose radii’s (R0.1,0.2,0.4,0.8,1.2,1.6,2.4,3.2) and complete round insert end mill on cutting forces and heat distribution between tool and the chip for PCD insert and compare the results with multi-layer (Al₂O₃+TiAlN+TiN) coated carbide tool at high speed cutting conditions using 3-D finite element numerical simulations. Results have shown that both tools due to their difference in thermal and mechanical properties have different behavior under the conditions studied especially when the complete round insert tool is used. The use of small nose radius tool when nose radius r_n is less than the axial depth of cut a_p, the forces and the temperature remains quite low and slightly increases with the increase of radius until r_n is smaller than a_p but when r_n gets larger than a_p and only some portion of nose radius is involved in cutting, then forces and temperature increases considerably. While when complete round insert end mill is used the forces and temperature significantly drops (more than 50% than the largest nose radius tool studied) at the same a_p for PCD insert but for multi-layer coated carbide tool it drops only slightly (20% than the largest nose radius tool studied). The reason for this difference lies in the fact that PCD tool has lower toughness, high hot strength and is more brittle than carbide tools and therefore maximum advantage can be taken only when small nose radius is used or when complete round insert tool is used as complete round insert have uniform stress distribution and also provides more stability for PCD tool material while large nose radius tool increases friction and also has more heat penetration in the tool thus resulting in higher cutting forces and temperature thus ultimately contributing in high wear of tool. While on the other hand carbide tools are only beneficial when smaller nose radius tool is used rather than round shape because of lower hot strength of the material.