Based on the continuous vibration equilibrium equation, the pulse function is used to present the material property, the influence of the local damage to the inherent frequency and the mode is deduced, especially the amendments function is advanced.

From the numerical results of a typical example,it can be seen that the dynamic stress intensity factor decreases with the damage factor increasing,showing the shielding effect of the damage to crack propagation under small-scale damage.

It is usually not the initial explosion but the secondary damage to pipelines and container system by flying missiles that results in the escape of flammable or even explosive fluids that leads to disastrous results.

The thesis narrates many kinds of current methods of prediction forearthquake damage to structures and development situation of research ontime-dependent quality, analyses merits and demerits of every method, points outimportance and characteristic of the thesis.

According to the principle of rigidity equivalent to the composite materials columns specimen must simplify the process of impact damage to the one-dimensional equivalent uniform columns collisions, applicated one-dimensional stress wave propagation theory to describe the destruction process of composite materials columns specimen.

There appear many Internet-scale worm incidents in recent years, which have caused severe damage to the society.

Chinese pine caterpillar (Dendrolimus tabulaeformis) larvae were fed with pine needles of different degrees of damage to evaluate the effects of pine needles on the growth and development of larvae.

The computed results show that the landing damage to the fighter and transport airplanes is 75% and 60% of the total damage, and the damage caused by the landing stroke is 40% of the landing-gear damage.

Pigments isolated from macromycetes and applied at a much lower concentration than those obtained from micromycetes prevented damage to bacteriophage-λ DNA induced by products of peroxidase-mediated degradation of aminobiphenyls.

At a low level of organic substrate, even strong colonization with microorganisms does not inevitably result in significant damage to metals.

The slot of gate is a necessary element of the hydraulic structures. Because of its complex shape and high velocities of flow, the water strongly mixes and vortexes mill form so that low pressures are occured near the slot. The cavitation nuclei in the water may grow under the low pressures and then collapse to damage the wall. Since the effect of mechanical forces can be considered as the main cause of cavltation damages to the kinds of chemical inert materials such as concret, it is necessary to...

The slot of gate is a necessary element of the hydraulic structures. Because of its complex shape and high velocities of flow, the water strongly mixes and vortexes mill form so that low pressures are occured near the slot. The cavitation nuclei in the water may grow under the low pressures and then collapse to damage the wall. Since the effect of mechanical forces can be considered as the main cause of cavltation damages to the kinds of chemical inert materials such as concret, it is necessary to study the movement and growth of cavitation nuclei near the point of the minimum pressure. For that, the flow field must be given. For streamlined bodies or boies having slight boundaty changes, their flow fields can be solved by the theory of perfect fluid or viscous fluid; but for bodies having great boundary changes such as the slots, their flow fields are complicated and their boundary layers may be separated at some places of the boundaries so that the flow fields cannot be decided by the above two kinds of theory. Only can the theory of turbulent fluid give precisely the results of flow fields. Recent years there have been many articles about calculations of mean turbulent flow fields, but few reported about calculations of mean pressure fields. In this paper, the finite analytic method and k-e turbulent model are employed to solve Reynolds equations. In two cases of Reynolds number being 104 and 2×104, the turbulent flow fields past the two-dimensional slot of gate are calculated by the vorticity-stream function method and the results are given for distributions of stream function, velocity, vorticity, turbulent kinetic energy, turbulent dissipation rate and turbulent viscosity on the basis of which the mean pressure coefficients are determined.In practice, the water flow near the slot of gate is three-dimensional, but as the first step of investigations the hypothesis of two-dimensional flow in the slot is made; furthermore, nonuniform grids are used in the calculation for fitting the boundaries and improving the results. Considering the wall effects, the wall functions are used so that the computational grids can be designed apart from the walls to diminish the influences of large gradients of the velocities near the walls and save the storage of the computer.From the computations of the problem, the effect of using k-e turbulent model to close the Reynolds equations is stated to be good and the finite analytic method is proved to be stable and convergent for the calculations of the turbulent flow fields of concaves. The calculated results of the mean flow fields are agreed well with the experimental data and the results of the mean pressure fields demonstrate mainly the characteristic of the pressure in the domain of the slot. But there exist some differences of pressure coefficients in the front of the slot, further improvements will be needed for obtaining better results of pressures. In the whole, the computational results are reasonal and satisfactory.In order to obtain real turbulent flow fields in the slot of gate, much more work will be needed such as the determination of three-dimensional wall functions, the invention of high efficient computational techniques and etc. These are now in progress.

The relationship between macroscopic damage and microscopic damage for concrete was constructed based on the proposed equivalence principle of energy dissipation. The ratio of axial damage to transverse damage is 0.1. According to the proposed relationship, the evolution of microscopic variables can be reflected through macroscopic variables, and can be measured easily. Conversely, there is a physical background on the evolution of macroscopic variables.

All the structural analysis now available are based on the assumption that the structures are in good condition But damages to structures can not be avoided in initial condition or in employment, and the damages will cumulate and become serious in the employment Damages not only shorten the life of structures, but also reduce their mechanical properties This paper lays its emphasis on the strength and stiffness reduction of member in which cracks exist The strengh reduction of metal...

All the structural analysis now available are based on the assumption that the structures are in good condition But damages to structures can not be avoided in initial condition or in employment, and the damages will cumulate and become serious in the employment Damages not only shorten the life of structures, but also reduce their mechanical properties This paper lays its emphasis on the strength and stiffness reduction of member in which cracks exist The strengh reduction of metal member under plane stess、 plane strain and elastic-plastic condition are analyzed, and the formulas of member residual strength are obtained The stiffness of members existing cracks are deduced based on the energy release principle Analysis for a tri member structure is conducted using the method presented in this paper, and the analysis results reveal that the reduction of member strength and stiffness due to craks has a remarkable influence on ultimate strength and reliability of structures