Simulation Analysis Of Special Macromolecule Sealing Products And Blending Modification Of Outer Sizing Of Composite Tubes

In recent years, rubbers and elastomers are widely used in national defence projects. Based on existing research foundation and finite element method, a software package "Rubber Seals Simulation and Analysis System" was developed to analyze rubber Seals of different materials and structures. The package can also simulate Seals under typical work conditions to coach structural optimization design and mould design, aiming for manufacturing long-life rubber Seals. Polymer physical modification method was selected for modifying outer sizing of TPU tubes. A new approach for improving abradability of TPU was brought forward. Some major works are as follow:1. Investigation of sealing mechanism based on finite element methodCombining with the sealing theories summed up by the pioneer, the process of finite element analysis was divided into two steps, one step was static analysis, the other step was dynamic analysis.The static analysis of sealing mechanism of O-ring、rectangular seal ring、 rubber-plastic combined seal and oil seal was belonged to contact problem, finite element software ANSYS used in this thesis adopted penalty element method to describe this problem. Based on the characteristic of the structure of each seal, two-dimensional axisymmetric finite element models were established to acquire maximal contact force, stress-strain contour and deformation under various work conditions. Based on the dynamic sealing theory, ANSYS CFX was preferred to simulate the flow condition in the sealing clearance. The difference between reverse segment and clockwise rotating segment and rotational frequency of the shaft influencing on the reverse pumping brought by the surface effect and the rotational frequency of the shaft influencing on the reverse pumping brought by the structure effect were analyzed. The simulation result has a well consistency with the experiment result, it proves the feasibility of the finite element method in analyzing the liquid.2. Development of "Rubber Seals Simulation and Analysis System"Using Visual Basic language for system interface development, APDL of ANSYS and Program of Pro/Engineer for secondary exploitation, we developed "Rubber Seals Simulation and Analysis System" with Access as database type, ANSYS as system kernel, Pro/Engineer as graphics exporting platform.The system is mainly composed of calculating module, plotting module and expert repository. Calculating module is core of the system, which enabled finite element analysis(FEA) of O-ring、rectangular seal ring、rubber-plastic combined seal and oil seal possible. The module was featured with friendly interface, simplifying the preprocessing of FEA, also making the modeling procedure concise to save a lot of computing time. During the simulation, embedded command macros hide the simulation backstage. So, it is more convenient for engineers to use it in a wide range.Plotting module was designed to provide an environment for drawing rubber sealing products and moulds. The module was based on embedded drawings. Plot of rubber sealing products and moulds can be easily created through parameter definition.Expert repository was a guidance for users, which was mainly comprised of general information about rubber sealing products. The module guide users to optimize their products.O-ring and oil seal was taken for example to introduce operation of the system. The system provides a referable approach to solve the design problem of sealing products. It account for a valuable engineering status.3. Blending modification of the outer sizing composite tubesAccording to the abrasion resistance problem of composite tubes, a blending modification method was put forward based on silver mark-shear zone theory. The effect of ethylene propylene diene monomer rubber (EPDM) as additives on the abrasion resistance of thermoplastic polyurethane (TPU) resin was investigated in this work. The mechanical properties and microstructures of the resultant TPU/EPDM composite were evaluated, and surface morphology of the composite after abrasion tests was examined. The results show that the addition of EPDM greatly improves both the mechanical properties and the abrasion resistance of the TPU resin. The TPU/EPDM composite with8wt%EPDM demonstrates the highest tensile strength, the largest elongation at break and the best overall performance. The abrasion resistance problem of composite tubes can be solved by applying blended TPU material, prolonging use life of composite tubes, saving energy and making contribution to manufacture of composite tubes.