Hai Bo Jiang

Calculations of the Elastic Modulus and Internal Stresses of Orthogonal Symmetric Laminated Plates

The calculations of the elastic modulus and the internal stresses of the orthogonal symmetric laminated plates are very difficult, so experimental or numerical simulation methods were used generally. This paper proposed an Equivalent Strain Model, which can greatly simplify the derivation process of the analytical formulas. By the Equivalent Strain Model, the elastic modulus formula of two-layer plate was derived, and the formula shows that the elastic modulus of the laminated plate meets to the mixture rule of the cross-sectional area ratio of each its single-layer plate; Other formulas derived show that the stress within each single-layer plate is proportional to its elastic modulus and the external load stress, and is inversely proportional to the elastic modulus of the laminated plate. The formula of the average shear stress between two single-layer plates also was derived. Recursive method can be used for multilayer plate calculations.

Calculation of Transverse Poisson’s Ratio of Continuous Fiber Reinforced Composites

This paper proposed a calculation model of transverse Poissons ratio of continuous fiber reinforced composite, in which the fibers are centrally arranged in a representative volume element. According to the equivalent strain rule of matrix and fiber in fiber direction, the formula of transverse Poissons ratio was deduced by mathematical method, which shows that the transverse Poissons ratio of the composite material is associated with the Poissons ratios and the elastic modulus of fiber and matrix. It was shown by an example that the transverse Poissons ratio of composite was less than the weighted average number of the Poissons ratios of fiber and matrix , even less than the matrix Poissons ratio in a large range. The minimum value indicates that the fibers obviously resist longitudinal deformation under the transverse force.

Relations of Lift and Drag Coefficients of Flow around Flat Plate

In this paper, when Reynolds number is within the range of 10000 to 1000000, the horizontal component of the total pressure of flow around flat plate at high angle of attack was regarded as lift of high angle of attack, and the vertical component was regarded as drag of high angle of attack. The horizontal component of total pressure at small angle of attack was regarded as shape drag, and the total drag coefficient at small angle of attack was considered to the sum of the shape drag and frictional drag at zero angle of attack. For the two states of large and small angle of attack, the application scopes of the formulas of lift and drag coefficients were given. Final, the relations of lift and drag coefficients were obtained by eliminating all angles of attack. Research results show that lift - drag curve of small angles of attack is parabola, and the lift - drag curve of high angles of attack is circle.

Reliability of Gravity Foundation in Coral Sands Subject to Dynamic Wind Load

Taking circular gravity foundation of high-rise structure in coral sands as research object, on the basis of mechanical analysis of foundation during inclination, the inclination vibration equation was established. The amplitude of foundation inclination was calculated. The inclination performance function of foundation was established. JC method is used to calculate the reliability index of foundation. Calculation shows that the amplitude of wind velocity has great influence on the reliability index of foundation when the frequency of sinusoidal wind pressure equals the natural frequency of foundation in inclination vibration. In the design of foundation, the natural frequency of foundation in inclination vibration should be made as far away from the frequency of fluctuating wind pressure as possible.

Calculation of Internal Stresses of Continuous Fiber Reinforced Composite Materials in Longitudinal Loads

Solving the internal stresses of continuous fiber reinforced composite materials is a complex problem, which was studied usally by experimental or numerical calculation method. This paper proposed the equal strain method with virtual external force compensation instead of considering the shear stress in the calculation of the stress in the fiber and matrix of composite materials. By the equal strain method, the formula of longitudinal elastic modulus of continuous fiber reinforced composite materials is derived. The same result was given by other literatures with other methods, which indirectly proved correctness of the equal strain method. Further the internal stress calculation formulaes of the fiber and matrix are derived. The formulaes show that the internal stress of fiber (or matrix) is proportional to the external load and the elastic modulus of the fiber (or matrix), and is inversely proportional to the elastic modulus of the composite material.

Variation of Wind Resistance Reliability of Foundation in Coral Sands

Considering variation of bearing capacity of foundation caused by crushing of coral sands, the variation of wind resistance reliability of foundation in coral sands was studied. Based on the use of exponential decay model of bearing capacity of foundation, the reliability index of foundation at different time was calculated. Calculation shows that in the mid-term of foundations life in coral sands, attention should be paid to the assessment of wind resistance reliability of foundation, and it is necessary to track the variation of wind resistance performance of foundation in time. After a long time of operation, assessment must be applied to the wind resistance reliability of foundation combining with inspection.

Analysis about the Feasibility of Power Generation through Renewable Energy on Coral Reefs

This paper analyzed the feasibility of development and utilization of four kinds of renewable energy sources which are wind energy, wave energy and ocean current energy, solar energy and gave some specific recommendations about the use of wind power. The richness of four kinds of energy sources and some problems about the cost, reliability, installation, utilization and maintenance were systematically investigated. Studies have shown that on the coral reefs solar power generation has the more feasibility than wind power generation, and wave power generation and marine power generation have no feasibility within future ten years.

Calculation of Settlement and Inclination of Gravity Foundation in Coral Sands Based on Transfer Matrix Method

Settlement and inclination of gravity foundation are calculated and analyzed using transfer matrix method. The influences of vertical load, overturning moment, foundation width b and deformation modulus of subgrade soil E on the settlement and inclination of foundation are analyzed. Calculation shows that increasing both the width of foundation b and deformation modulus of subgrade soil E can improve the anti-overturning performance of foundation, and reducing the foundation width and increasing the deformation modulus of subgrade soil can reduce the subgrade settlement. This method can effectively calculate the settlement and inclination of gravity foundation.

The Equal Projection Model and Application of Short Fiber Reinforced Concrete

In order to determine the fiber direction distribution statistical characteristic of short fiber reinforced concrete, this paper put forward the equal projection model. According to the isotropic assumption of large volume of short-fiber reinforced concrete, in the three-dimensional coordinate system, when the concrete loads along all coordinate axes are equal, it is believed that a representative short fiber projection components in all axes are equal. According to the deduction, the cosine of the angle of the representative fiber and the force direction is equal to the reciprocal value of the square root of 3. On this basis, as an application example, the formula for the prediction of fiber reinforced concrete elastic modulus was deduced. The formula shows that the elastic modulus of short fiber reinforced concrete is equal to the sum of 1/3 of the elastic modulus of long fiber concrete in fiber length direction and 2/3 of the elastic modulus of long fiber concrete in the vertical direction.

Problems and Solutions of Solar Energy Development and Utilization in Coral Reefs

To develop and take advantage of wind energy resources in the South China Seas coral reefs, the paper discussed the situation of local wind resources, typhoon, corrosion, geology, wind turbine transportation and installation problems. The analysis indicates that the South China Sea typhoon-prone, serious corrosion, bad geology will cause many difficulties to installation and use of wind turbines. Authors believe that, installing and using small wind turbine in the coral reefs is feasible, but the suitable measure of anti-typhoon, anti-corrosion, transportation, installation and maintenance must be accepted, which needs a great deal of budget support.