WT5BZ]Flexural properties of C/C composites was investigated at the temperature of 20℃ to 1400℃ It′s found that as the span to depth ratio increases, the bending strength rises but the shear strength reduces When the span to depth ratio is greater than 8, the bending strength tend to be constants The span to depth ratio is independent on temperature in the range of 20℃ to 1400℃

According to Timoshenko-Mindlin theory of thick plates, strain energy equivalence hypotheses and Boltzmann superposition principle, the nonlinear dynamic equations of viscoelastic laminated plates including the effects of damage and transverse shear deformation are given.

The dependence of the measuring conditions for smallsample on the bending strength is discussed and therepeatability of the bending strength obtained bythis method is examined.

The calcvlatedresults show that when the ratios betweenthe thickness and height are larger than5～8 the thin plate theory has certainaccuracy, but there is a large amount oferror in the solutions by thin plate theoryfor parts with smaller ratios such as gears.

Effects of test pieces' size of bamboo composite board (the ratio of width to thickness and the ratio of test span to thickness) on the test values of MOR and MOE were studied by quadratic orthogonal rotational combination design test.

Furthermore it is shown that the magnitude of shear deflection depends on both the span to depth ratio of the beam and the elastic properties of the species involved.

It increases as the effective span to depth ratio of the composite beam decreases and as the core ratio of pure modulus of elasticity to modulus of rigidity increases.

Approximate analytical expressions for the second, third, fourth and fifth terms for a TPB with a span to depth ratio of 4 and for a single edge notched beam subjected to pure bending are obtained by fitting the computed data.

These approximations are then used to predict the general expressions for coefficients of the higher order terms of a TPB with arbitrary span to depth ratio β.

The specimens were of square cross section with a span to depth ratio of 2/5.

Transverse shear effects are important for the bending and vibration of laminated plates. When a laminate is in bending, it is assumed in this paper that the transverse displacement is constant through the plate thickness, and the in-plane displacements vary linearly through each layer, i.e., they are piecewise linear through the plate thickness. The latter means that the transverse shear strains within each layer area assumed to be different each other. There are two methods to relate the transverse shear strains...

Transverse shear effects are important for the bending and vibration of laminated plates. When a laminate is in bending, it is assumed in this paper that the transverse displacement is constant through the plate thickness, and the in-plane displacements vary linearly through each layer, i.e., they are piecewise linear through the plate thickness. The latter means that the transverse shear strains within each layer area assumed to be different each other. There are two methods to relate the transverse shear strains within each layer:(1) Demand the continuity of two shear stress components at all inteifaces. It is equivalent to that transverse shear stresses are constant respectively through the plate thickness.(2) Assume that transverse shear stresses vary parabolically through the plate thickness. These two methods correspond with two models of the displacements of the laminate, called Piecewise (1) and Piecewise (2) schemes respectively in this paper. According to these two schemes, the governing equations for the bending of a specially Orthotiopic laminate under a lateral load are obtained on the basis of the principle of minimum potential energy. The unknown functions are Wom,ψxo and ψyo which are the transverse displacement and rotational angles of normals to the central layer of the laminate respectively. After Wom,ψxo and ψyo have been solved the in-plane displacements and stresses within each layer can be further obtained. Thereafter the transverse shear stresses can be given by integrating the equilibrium equations in elasticity. As for vibration problems, the similar governing equations and the boundary conditions of the laminate are derived from Hamilton's principle. Three examples are calculated. They indicate that a good estimate of displacements, stresses and natural frequencies of laminates can be given in accordance with the two schemes in this paper, even though the span-to-depth ratios of laminates are small. When a laminate is consisted of a large number of layers, the results calculated according to Piecewise(2) scheme may be bettter.

The comparable ratio of the bending strengthbetween plastics big and small samples is studied.The dependence of the measuring conditions for smallsample on the bending strength is discussed and therepeatability of the bending strength obtained bythis method is examined.

Basing on the simplifiedRessner's Equations of thick elastic plate,this paper deals with the problem of ben-ding strengsh of gear tooth through ana-lysing the bending problems of a thick canti-lever-plate of infinite length and a halfspace protrusion thick plate. The calcvlatedresults show that when the ratios betweenthe thickness and height are larger than5～8 the thin plate theory has certainaccuracy, but there is a large amount oferror in the solutions by thin plate theoryfor parts with smaller ratios such...

Basing on the simplifiedRessner's Equations of thick elastic plate,this paper deals with the problem of ben-ding strengsh of gear tooth through ana-lysing the bending problems of a thick canti-lever-plate of infinite length and a halfspace protrusion thick plate. The calcvlatedresults show that when the ratios betweenthe thickness and height are larger than5～8 the thin plate theory has certainaccuracy, but there is a large amount oferror in the solutions by thin plate theoryfor parts with smaller ratios such as gears.