Yan Ru Li

Experimental and Economic Analysis of Airport Crumb Rubber Concrete (CRC) Pavement

The feasibility of using crumb rubber concrete (CRC) in airport pavement is discussed by analyzing the capability of crumb rubber concrete. The bending property of CRC is studied by four point loading test of small-sized rubber concrete beams. Comparing with cement concrete (CC) pavement, the board thickness of CRC pavement is analyzed. The conclusions are reached that appropriate mixing of crumb rubber could satisfy strength demand and improve durability of airport pavement, and the thickness of CRC pavement is 93 percent of that of CC pavement. As a result, airport CRC pavement has longer service life and perfect cost performance.

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.

Analysis on Mechanical Properties and Durability of the Chopped Basalt Fiber Reinforced Concrete

The current research situation of basalt fiber reinforced concrete was analyzed on the basis of the previous research results. When concrete is incorporated with basalt fiber, the compressive performance of concrete is instable, the tensile strength changes along with the fiber content, but the durability improves significantly , and the bending performance and impact resistance has more obvious improvement. According to the characteristics of chopped basalt fiber reinforced concrete, the prospect of the application of basalt fiber reinforced concrete is explored.

Discussions of Tire Ground Pressure Distribution Model

Though there have been some experimental studies to discuss laws of grounding shape and grounding pressure, the acknowledged mathematics model has not established. In order to discuss the law of tire ground pressure distribution, pressure distribution models of round rectangles grounding shape and ellipse grounding shape are advanced differently. Parameters setting method and 3-D graph of different ground pressure distribution are presented, and expressions of ground area, mean ground pressure, most ground pressure and the normal stress on the ground are deduced. Results show that the grounding shape of tire is close to ellipse or rectangle as load varying, and the distribution of grounding pressure express convex or concave under different tire pressure and loading.

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.

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.

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.

Development of the Stress-Strain Relationship for Crack Diffused Concrete

On the basis of diffusion mechanism of crack and stress-strain of concrete, the mathematical differential formula and the pure theoretical model of stress-strain complete process of concrete are established. It is shown that stress-strain relationship of concrete is affected by Hooke’s law and diffusion mechanism of crack, and the law of which can be expressed by an exponential formula.