Xiao Ren Lv

The Swelling Properties of Nitrile Rubber with Different Acrylonitrile Contents in Cyclohexane Medium Research

By the research of swelling and mechanical properties of nitrile rubber with different acrylonitrile contents in cyclohexane medium, the influences of physical and mechanical properties with diffrent acrylonitrile contents is analyzed. The results indicated that: the quality of all the nitrile-butadiene rubbers with different acrylonitrile contents is increasing with the increase of soaking time. It increases rapidly in the first 24 hours then gently. With the increase of the acrylonitrile content, the increasing proportions of swilling quality is reduceing. But N40 cyclohexane performance is better relatively. After drying the three kinds of rubber in 110 degrees Celsius, all the qualities is lower than the original value. It means that in swelling process, the material in rubber is pulled out and the distance between the rubber molecules decreases. After swilling the three kinds of rubber, their hardness decreases and the decline proportion is reducing by the increase of acrylonitrile content. With different acrylonitrile contents and swilling times the nitrile rubber shows different mechanical properties. After soaking three kinds of rubber their tensile strengthes are on the decline by swilling time and their rates of permanent deformation are on the rise. It shows that as the swelling time extended, the mechanical properties descends and the corresponding indicators after soaked and dried is lower than the quantitative values after soaked. The study has a certain reference of design of ESPCP stator under certain operating conditions.

Influence of Liquid Paraffins in Crude Oil on the Friction and Wear Behaviors of the Progressing Cavity Pump`s Stator Rubber

The progressing cavity pump (PCP) always works in the waxy oil well. Therefore the research on the influence of various liquid paraffin contents in crude oil on the friction and wear behaviors of the progressing cavity pump`s stator is very important for choosing the best stator rubber and developing the service life of PCP. Wear behavior of nitrile butadiene rubber (NBR) and fluororubber (FKM) was investigated at room temperature using a reciprocating friction and wear testing machine under the various paraffin contents in crude oil (0%、10%、30%、50%、100%). The wear morphology of blend was analyzed through the stereomicroscope and the wear behavior of two blends was also discussed and compared. The results show that the wear resistance of FKM is better than that of NBR under the same paraffin content in crude oil; With the increase of the paraffin content, the wear and coefficient of friction also increase. When the paraffin content in crude oil is less than 30%, the wear loss of NBR and FKM are basically the same; When the paraffin content in crude oil is more than 30%, the wear loss of NBR is far more than that of FKM.

Research on Friction and Wear Behavior of Rubber in the Mixture of Crude Oil with Water

In order to choose the rubber material and improve the service life of Progressing Cavity Pump (PCP ) when exploiting offshore crude oil, it is important to analyze friction and wear behaviour of stator and rotor of PCP in the mixture of crude oil with different water content. The friction and wear test about Nitrile -Butadiene Rubber (NBR) and Fluorine Rubber (FKM) were carried on ring-on-block tester, the wear loss was observed by electron microscope, the wear mechanism was also discussed. The results show that: (1) FKM owns better wearing resistance than NBR in the mixture of crude oil with different water content; (2) when the content of water in the mixture is less than 26%, the frictional coefficient of sample is 0.05, due to the oil film between the friction pairs; (3) when the content of water in the mixture is more than 26%, the frictional coefficient increases to 0.4, because of the water film between the friction pairs.

Finite Element Analysis of Stress for Nozzle Zone at Channel of Pressure Vessel

With the development of petrochemical industry, the status of pressure vessel has become increasingly important, and higher requirements are introduced for the security of nozzle zone at the pressure bearing region of pressure vessel. In order to study the stress status of nozzle zone at the channel of pressure vessel, solid modeling for channel and straight pipe was performed with ANSYS software. Through finite element analysis and calculation, the stress concentration region of channel was determined and the reason was analyzed. In addition, the nozzle zones of the model before and after loading were compared. The result reveals that symmetrical stress concentration region lies at the junction of channel and pipe. The maximum stress is located at the inside of nozzle zone of channel and less than the yield stress of material.

Concurrent Topology Optimization of Lightweight Cellular Materials and Structures

In this paper, a two-stage optimization algorithm is proposed to simultaneously achieve the optimum structure and microstructure of lightweight cellular materials. Microstructure is assumed being uniform in macro-scale to meet manufacturing requirements. Furthermore, to reduce the computation cost, the design process is divided into two stages, which are concurrent design and material design. In the first stage, macro density and modulus matrix of cellular material are used both as design variables. Then, the optimum topology of macro-structure and modulus matrix of cellular materials will be obtained under this configuration. In the second stage, topology optimization technology is used to achieve a micro-structure of cellular material which is corresponded with the optimum modulus matrix in the earlier concurrent design stage. Moreover, the effectiveness of the present design methodology and optimization scheme is then demonstrated through numerical example.

Research on the Friction and Wear Properties of the NBR under Dry Sliding and Water Lubrication

The wear mechanisms of different graphite contents of NBR by 45# steel under dry sliding and water lubrication were investigated. On MPV-600 computer-controlled abrasive wear testing machine, the coefficients of friction were measured continuously. Results showed that under dry sliding condition, the rubber wear loss is big, the coefficient of friction is higher, the temperature of the friction surface is rise obviously. Wear loss and friction coefficient of NBR decrease with the increase of graphite contents; With the increase of graphite contents wear loss and the friction coefficient decreases, and is mainly due to the graphite lubrication performance and increase the stiffness of the rubber contact area. At low content of graphite, adhesive wear of NBR is showed, in the high content of graphite, abrasive wear is showed. Water lubrication condition, wear surface level off, the wear loss is very small, and the lubrication and cooling effect of water makes the friction coefficient decrease. Graphite content is higher, the wear loss and coefficient of friction is smaller.

The Research on the Friction and Wear Behavior of FKM/NBR Blends under Water Lubrication

In this paper, the friction and wear behavior of FKM, NBR and FKM/NBR blends with the same Shore hardness was investigated in the MPV - 600 wear tester under water lubrication based on the actual working parameters of the screw pump. Wear mechanism of FKM/NBR blends with different load was also analyzed according to their wear loss and frictional coefficient. The results showed that the wear resistance of NBR was improved by the addition FKM. FKM/NBR blend with ratio of 2:8 owned the optimal wear resistance, which was close to that of FKM. The wear of FKM and FKM/NBR blend with ratio of 2:8 was controlled by fatigue wear, and the others were mainly controlled by abrasive wear.

Study on the Pressure Distribution on Solid-Plug Conveying of Centrifugal Extruder

In this paper, a new polymer process machine--- centrifugal extruder is introduced. The performance of centrifugal extruder had been studied by theoretical analysis. The analysis shows that the centrifugal force field can provide the solid-plug conveying pressure sufficiently and stably, which can prove the industry practicability of centrifugal extrude. By further discussion, it shows that the important influencing factors on the pressure comprise the structural parameters of the rotors and the rotation velocity.

Study on the Friction Properties of Surface Iodide Modified Nitrile Rubber

After Iodide modification using KI solution on the surface of nitrile rubber, the treatment effect on the friction properties of nitrile rubber are explored. Experiments using different concentrations KI solution, soaking the samples for different time, the friction properties of the samples are tested under different load and lubrication. The results showed that, under different conditions, the surface of iodide modified nitrile rubber is dense and smooth, with the increase of KI concentration and soaking time, the degree of iodide modification is deeper, and the friction properties of NBR is also significantly improved.

Short-Term Prediction on the Time Series of PCP Speed Based on Elman Neural Network

Elman neural network is a classical kind of recurrent neural network. It is well suitable to predict complicated nonlinear dynamics system like progressing cavity pump (PCP) speed due to its greater properties of calculation and adaptation to time-varying with the comparison of BP neural network. This paper provides one method to create, predict, and decide the model of PCP speed based on Elman neural network. At the same time, short-term prediction is made on time series of PCP speed using this model. The results of the experiment show that the model owns higher precision, steadier forecasting effect and more rapid convergence velocity, displaying that this kind of model based on Elman neural network is feasible and efficient to predict short-term PCP speed.