Applied Mechanics and Materials Vol. 248

Abstract: Ocean environment loads such as wave, current and wind load shows random distribution. The coupling of different kinds of load can easily lead to the fatigue damage of offshore platform structure. The damage presented the multiaxial characteristics would be formed in different directions and planes. K-joint is the key but weak part of the platform structure. This paper associated macro ocean environment factors with material interior micro structure change to reveal the microscopic mechanism of fatigue damage evolution and fatigue damage evolution regularity. By building finite element model of the offshore platform K-joint and physical model, an experiment is done under the function of wave and current load and makes a good result. In this way, the relationship between them and fatigue life was established, and the result agreed with the theoretical predictions.

Abstract: It aimed to dynamic change of oilfield productivity, maked sure that the progressing cavity pump is working in a highly efficient region. It combined variable frequency conversion technology and dynamic liquid level height control technology, the closed-loop control of oil production system with progressing cavity pump is made up of rotation-speed and torsion sensor, stepless motor, frequency converter, PLC and progressing cavity pump. The result show that the system can control the pump submergence depth by adjusting the rotation-speed and torsion of polish rod, and make sure the pump working in a highly efficient region finally. This system also can increase recovery efficiency and pump service life.

Abstract: Jet pump has different basic characteristics when it is used in different application condition. According to jet pump structural design matching technological parameter used in the oilfield unloading system, research on four kinds of numerical simulation algorithms. They are work characteristics of ground power pump model, target liquid production model, current pressure model and pump setting depth model. The results show that the four models can meet the needs of structural design and technological parameter calculation in different conditions. This paper form system theory, provide for pump design and selection matching for jet pump unloading system used in well.

Abstract: The foundation and core of the phased modeling non-homogeneous modeling, Shengtuo oilfield geological modeling of the low porosity and permeability reservoir description of the characteristics of data is small, the accuracy is low, uncertainty factors. Using phased stochastic modeling techniques, log interpretation, based on data combined with core analysis, production performance and other known information, the sedimentary facies model as constraints holes, seepage property modeling to reduce the reservoir description is not uncertainty, combined with sequential Gaussian simulation method to establish a geological model of the actual production status of the oil region, the geological basis for the block rational development decisions and improve the effect of oilfield development.

Abstract: Based on frequency equation of simply supported ring-stiffened cylinder, an alternative approach for calculating natural frequencies of ring-stiffened cylinder is proposed. Using some transformation techniques, the frequency equation is converted to determinant form of matrix pencil. Thus, solving frequency equation is equivalent to calculating generalized eigenvalues of matrix pencil. Then the natural frequencies of ring-stiffened cylinder are acquired with QR method. The result of QR method agrees well with that of bisection method and finite element method. By reducing order of the determinant, a simplified formula for calculating the minimum natural frequency of ring-stiffened cylinder is given. It proves that the simplified formula meets accuracy requirements when rings have small stiffness through comparing results from QR method and simplified formula. Using the approach of this paper, natural frequency’s curves of ring-stiffened shell are compared with that of unstiffened cylinder, while the effects of ring’s number and stiffness on natural frequencies are investigated.

Abstract: This paper is studying the fluid mechanics and heat transfer along the surface of are-type slotted fin in the finned heat exchanger by using the simulation software comsol multiphysics. The major study is the effect of the structure of fin to the fluid mechanics and heat transfer process, including the fin pitch, height of arc-type slit, the size of arc-type slit, the position of arc-type slit. And drawing the following conclusion: under the condition of low velocity, the fin pitch should be around 2.0 mm in considering the overall heat-transfer performance, and under the condition of large velocity, around 1.5 mm is better; When designing the arc-type slotted fin, the more larger the height of arc-type slit do, the better the overall heat-transfer performance; it is better if the start angle, as same as the position of arc-type slit, is less than 30°; the angle of arc-type silt ,as same as the size of arc-type slit, should be larger under the condition of meeting the demand of pressure drop.

Abstract: For coupled plate-shell structure, restraining the vibration transmitted from plate to shell is an important approach to reduce the mechanical noise from the shell. In this paper, a damping sandwich arch profile with rubber as the material of the damping layer is presented and manufactured. Structure vibration response with arch profile applied to the coupled plate-shell test model is measured. And then Statistics Energy Analysis method is used to analyze the effects of major parameters on anti-vibration performance of the arch profile. Research indicates that using damping sandwich arch profile can restrain the vibration response of the shell effectively.

Abstract: Current methods to estimate the behaviour of composite structures are based on trial and error or oversimplification. Normally the nonlinearities in these structures are neglected and in order to cover this inadequacy in design of composite structures, an overestimate safety factor is used. These methods are often conservative and leading to the heavier structures. A novel technique employs Artificial Neural Network (ANN) as an inverse problem approach to estimate the pressure loads experienced by marine structures applied on a composite marine panel from the strain measurements. This can be used in real-time to provide an accurate load history for a marine structure without requiring knowledge of the material properties or component geometry. It is proposed that the ANN methodology, with further research and development, could be utilised for the quantification of in-service, transient loads in real-time acting on the craft from the craft’s structural response (strain response to load). However, to fully evaluate this methodology for load monitoring of marine structures further research and development is required such as sensor optimisation. The number of sensors should be minimised to reduce the time to train the system, cost and weight. This study investigates the number of sensors required for accurate load estimation by optimising the method.

Abstract: This paper established the finite element model of a hydrostatic guideway. Based on the thermal characteristic simulation analysis, the temperature field and thermal deformation of the guideway were obtained. The analysis results show that the oil film temperature increment will cause thermal deformation of the guideway and processing errors. The errors will influence the machining accuracy of machine tools. The analysis results provide certain theory basis for the research on the above influence. And then the results also give certain reference for the research on the thermal error compensation of machine tools.

Abstract: This research studied quality engineering design of FML (Fiber Metal Laminate) under concentrated load. 1st DOE (Design of Experiment) was conducted to find out vital few Xs. 16 experiments were performed and their results were statistically analyzed. Pareto chart analysis shows that the thickness of fiber prepreg and metal laminate are more important than the material property of fiber prepreg or stacking sequence angle. Also, the stacking sequence of 1st layup prepreg is more important than that of 2nd layup prepreg. The main effect plots shows that the maximum deflection of FML is minimized with increasing layer thickness and modulus of metal laminate. 2nd DOE was conducted to obtain RSM (Response Surface Method) equation. 27 experiments were conducted. The CCD (Central Composite Design) technique with four factors was used. The coefficient of determination (R2) for the calculated RSM equation was 0.97. Optimum design was conducted using the RSM equation. MMFD algorithm was used to optimum design. Optimum values for thickness of prepreg, thickness of metal, modulus of metal, fiber orientation 1 and fiber orientation 2 are 0.135mm, 0.135mm, 80GPa, 0O, 0O, respectively. Quality engineering design was conducted to find out guideline for control range of design parameter. To acquire six sigma level reliability, the standard deviation of design parameter should be controlled within 1% of average design value