[en] The fiber-wound composite cylindrical shell has the characteristics of simple structure, high specific strength, high specific rigidity, strong design and high bearing capacity, and is widely used in pressure vessels, aviation, aerospace and military industries. At present, the cylindrical shell we use usually consists of a small angle layer and a circumferential layer, after the small angle layer is wound and formed on the core mold, it needs to be de molded into the initial test piece, and then subjected to large tension secondary winding forming, improper design is likely to cause entanglement instability problems. In this paper, the Ritz method theory is used to derive the stability equation of the small-angle layer shell, and the critical instability pressure and the prestressing force are obtained, then the initial test piece lay-up structure is given in combination with the actual winding process, and the material parameters and cylindrical shell are also carried out, the influence of wall thickness factors on critical instability pressure. This study provides theoretical support for the rational design of fiber-wound composite cylindrical shells. (authors)

[en] Composite is widely used owing to its excellent stiffness and strength performance. For rotating machine, in order to satisfy with structural stiffness and strength, the composite cylindrical shell is usually composed of spiral wingding layer and hoop winding layer, it gives rise to mechanical anisotropic which is different from that of metallic material, so that the difficulty of the structural design optimization is highly increased. Based on the thin-shell theory, the expressions of multilayer composite cylindrical layer stress are derived, and the effects of some factors such as the material parameters, layering system, winding angle, thickness of cylinder are studied. The results obtained can be applied in optimization design on the composite cylindrical shell of rotating machine. (authors)

[en] For resin-based composites,the effect of moist heat environment on its properties is very obvious. Water can penetrate into the interior of the composite through diffusion and capillary-action, resulting in plasticization, swelling and hydrolysis of the resin matrix. Plasticization and hydrolysis directly affect the glass transition temperature of the resin. On the other hand, swelling and liquid can cause micro stresses inside the material, causing the polymer macromolecular chain to stretch or even break, and at the same time lead to weakening of the interface properties of the resin and the fiber, which leads to a decrease in the strength and rigidity of the composite. In this paper, the hygroscopic properties of resin materials were analyzed by moist heat test. The effects of different temperature and humidity conditions on the chemical structure and glass transition temperature of the resin were studied, so as to study the influence of temperature and humidity on the hygroscopic properties of resin-based composite. The experiment obtained the law of hygroscopic properties of the resin. At the beginning of the test,the moisture absorption was faster. With the prolongation of time, the moisture absorption gradually became balanced, and the higher the temperature and humidity, the greater the moisture absorption of the resin. Under the different temperature and humidity conditions, the chemical structure of the resin material itself is not significant changed. The results showed that the glass transition temperature of the resin material decreased after the moist heat test, and the higher the temperature and humidity, the greater the decrease. Among them, the temperature change has a greater influence on the glass transition temperature of the resin. (authors)

[en] For the composite material cylindrical shell material properties test, usually using the material properties of the laminate test method, that is, in the composite cylindrical shell on the specimen for performance for performance testing, this method will destroy the integrity of the structure, so that fiber discontinuity, the greater the impact of the boundary effect, so that the test results deviation from the true value. In order to make the measured results as close as possible, the method of increasing the width of the sample is usually adopted, the increase of the sample width will increase the difficulty of the test, the increase of the sample width will also need to consider the influence of the curvature of the cylindrical shell itself. In order to solve the above problems, this paper designs the special equipment to rotate the composite cylindrical shell at high speed, and uses the special test equipment to measure the of the cylindrical shell in the axial and radial directions, and combined with the theoretical calculation, the mechanical properties of the fibre-wound cylindrical shell composite can be obtained. Compared with the traditional method, the method has the advantages of accurate test date, convenient sample preparation, no damage of the test pieces, and small external factors. (authors)

[en] Objective: To discuss how to diagnose and treat thymoma associated with pure red cell aplasia (PRCA). Methods: Three patients of thymoma associated with PRCA were treated with thymothymectomy, and the local radiotherapy was conducted after operation for avoiding the thymoma reproduction. Determining of their peripheral blood hemoglobin was used to evaluate the postoperation result in PRCA. If PRCA can not be relieved, oral prednisone and cyclosporin A were given. Results: One patient with PRCA was cured, the second patient remained in remission by treatment with prednisone and CsA, and the third patient was in progress. Conclusion: The treatment by means of 'thymothymectomy-local radiotherapy-use of prednisone and CsA', is effective for thymoma associated with PRCA

[en] High performance aramid fiber is a high strength, high modulus, low density and good wear resistance of high-tech fiber, has been widely used in aviation, aerospace, military and other fields. But aramid fiber is a high molecular organic synthetic materials, under the long time stress there may be viscoelastic deformation, namely creep occurs, once the creep larger, is bound to affect the stability of fiber composite structure size and performance may eventually lead to structural parts failure. Therefore, considered from the point of view of engineering application, the aramid fiber to carry out study on creep properties is very necessary, the aramid fiber impregnated yarn creep properties under long term high were tested and analyzed by the suspension manual measurement method, the result show that aramid fiber in high load with high ability anti creep, 10 months creep deformation is less than 0.1% and with the extension of time, the creep basically unchanged. The influence of creep properties on the structure of aramid fiber can not be considered in practical application. (authors)

[en] The metal end cap is assembled by interference fit with composite cylinder which is thin-walled cylindrical shell structure, and the interference fit surface of the end cap and the cylinder is a thin wall structure. It is necessary that the end cap and the cylinder are fitted in place and at the same time the parts can't be damaged by the interference fit compression force, so an appropriate interference fit compression force should be applied according to the different magnitude of interference. Through the way of finite element analysis and theoretical calculation, the compression force when assembly is in place is the minimum compression force, and the minimum axial pressure which will cause cylinder instability is the maximum compression force. In this paper, a calculation method of interference fit force of thin-walled structure is established that play a guiding role in the actual assembly. (authors)

[en] The carbon fiber composite cylindrical shell are composed of spiral winding layer and hoop winding layer, for researching the spiral winding layer stiffness degradation rule of the carbon fiber cylindrical composite shell with rotating load, based on the thin-shell theory, the analytical expressions for the model frequency of the cylinder are derived by creating the differential equations for the shell and then per 50 s^-1 velocity increased test is designed to getting frequency change rule after test by experimented, at last the results of spiral winding layer stiffness degradation rule is obtained by theoretically analysis agrees with the frequency change rule, and the others material parameters have no change. We should take stiffness degradation into account when designing the carbon fiber cylindrical composite shell with rotating load. (authors)

[en] High hard and high brittle material is often used in the mechanical industry. This kind of material usually has high stress after machining and assembly. The existence of high stress sometimes causes the fragmentation of the components, or even the damage of the facility. So we should study on the stress after the assembly of components, to make the stress of brittle material components evenly and make the components of high reliability. This paper takes the cylindrical brittle material rigged out in the cylindrical hole as an example, uses finite element software to analyze the stress, and optimize the structure of the components based on the situation of stress distribution. As we analyze the stress again after the structure optimization, the result shows that it makes sure of the same size of working surface, distributes the assembly stress evenly, makes the high stress point far from the working surface, and reduces the probability of components, fragmentation caused by the concentrated stress of the brittle material. (authors)

[en] In the deep mining of mines, the choice of air volume needs to consider both the cooling effect and the energy consumption. In order to obtain the basis for selecting the suitable air volume in the horizontal roadway, based on the theory of heat transfer and thermodynamics, the heat transfer relationship in the horizontal roadway is analyzed. The study found that the suitable air volume mainly considers the influence of three parameters: air self parameters, roadway specification parameters and temperature boundary parameters. As the air volume increases, the cooling effect gradually decreases, and the energy consumption gradually increases. After the air volume reaches a certain value, the cooling effect is basically unchanged, and the energy consumption is too high to bear. (paper)