Being considerably stiffer, lighter and more damped than metals, fibre reinforced plastic composites are increasingly replacing metal alloys used traditionally in weight sensitive structural applications. However, the hybrid nature of FRP composites has a far more significant bearing on vibration properties of structures made from these materials than metals. Presented here is a review of some fundamental aspects of vibration damping in general, and of vibration properties of structural FRP composites in particular. Both experimental and analytical aspects of studying these properties are considered. This, it is hoped, will provide a reasonably broad appreciation of vibration characteristics of structural FRP composites, and of the work done to study these characteristics.

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This paper is aimed at the construction of a lower bound rigid plastic constitutive model for the plastic deformation and micro void evolution process of porous materials. In this model a lower bound yield loci for porous materials is taken as one of the pillars of the theoretical system. To overcome the obstacles to the establishment of rigid plastic theory, a few concepts such as the effective stress, effective strain rate, nominal effective stress, nominal effective strain rate, generalized triaxiality ratio and generalized triaxiality function are defined from the lower bound meaning. The physical meanings of these concepts are systematically annotated. The potentialities to predict and control the strength and ductility of porous materials under forming by applying respectively the effective stress and generalized triaxiality function are discussed. The lower bound model together with the upper bound model in previous research will form a perfect and complete theoretical system that may enable us to simulate the real plastic deformation and damage evolution much more accurately by rigid plastic analysis.

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A numerical method based on integration along bicharacteristics is presented for analysing two-dimensional stress wave propagation problem in layered orthotropic plates. This method is an extension of the method proposed by Clifton isotropic plane problem. The numerical stability is discussed. The method is applied to simulate stress wave propagation in a semi-infinite plate composed of two different orthotropic materials.

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By using a molecular dynamics method, a film formation in an early sputtering process was modeled, and structural properties of Al thin films sputter-deposited on Al crystal substrate were simulated. Simulations were conducted for modeled sputtering conditions which were specified by the substrate temperature T_si and the incident energy of atom E_i. When the substrate temperature was changed, no significant difference was observed in the radial distribution function, though an island-like structure was remarkable in the film simulated for a lower T_si. Structures of simulated films were generally near crystal type in the entire region of E_i investigated in this study. To discuss simulated structures quantitatively, an apparent density was defined for a simulated film. The defined apparent density of film was smaller in the region of lower E_i, Where the island-like structure occupied a larger portion in a film. The apparent density was also found to increase with increasing T_si and/or E_i.

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In this study, a method for the regularization of the boundary value inverse analysis is proposed. The method is that the fundamental solution in B.E.M.is selected satisfactorily according to the prolem to be solved and the rank of the coefficient matrix constructed using the satisfactory fundamental solution is reduced for the regularization. The optimum condition for solving the boundary value inverse problem is found by using the objective function which consists of the condition number of the coefficient matrix and the error norm caused by the rank reduction of the matrix. In a numerical example, the optimum conditions to the inverse problems governed by the two-dimensional Laplace equation and the plate bending eqation are found. It is shown that the optimum condition obtained by the proposed method is more adequate than that obtained by the conventional method, from the viewpoint of the objective function. The proposed method is therefore proved to be effective for the inverse analysis in B.E.M.

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Cellular Automata(CA) are examples of dynamical systems which exhibit"self organizing"behavior with increasing time. They are useful in modeling modular systems. One such application of modularity is described in this paper where a structural plate is considered as composed of smaller"structural modules"which are considered as cells in a lattice of sites in a CA and have discrete values updated in discrete time steps according to local rules. These local rules are generally fixed in a CA, but we consider these rules as evolvable. To evolve the local rules, we use the Genetic Algorithm(GA) model. In this paper, two structural optimization methods by Evolutionary Cellular Automata(ECA) are presented. ECA is a Cellular Automata(CA) which is optimized for computation of certain problems by the Genetic Algorithm(GA). The first method is called"Direct Rule Encoding"and the other is called"Indirect Rule Encoding". Direct Rule uses configuration of the neighborhood state as the CA's input. Indirect Rule uses the"Ratio"between given cells' stress and sum of neighborhood stresses. These two methods are applied to minimize weight design problems and adaptive solutions are obtained From this experiment, we observe that Indirect Rule is effective in large scale problems.

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The purpose of this research is to apply biomimetic designed composites to artificial structures. Looking at the bio-joint mechanism, the solid-fluid composite structure of the cancellous bone is likely to play a great important role in the load transmission. So, the solid-fluid composite model equal to the cancellous bone was made by using honeycomb structure. Static indentation testing was carried out, and in-plane deformation conditions of the solid-fluid composite specimens were measured quantitatively. Experimental results illustrated that the hydrostatic pressure of the fluid phase greatly influenced on the in-plane deformation condition of the solid phase. Consequently, as for the solid-fluid composite models, the compressive load dispersion by the solid-fluid phase interaction was expected.

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The failure process of the Si-Ti-C-O fiber bonded ceramic material was investigated under tensile and flexural loading conditions. Tensile and three-point bending tests showed the significant difference between the failure modes caused under the two types of loading. The tensile failure process was calculated using a Monte-Carlo simulation method based on a Shear-Lag model. The calculation successfully predicted the distribution of the tensile strength of the Si-Ti-C-O fiber bonded ceramic material. The finite element method was employed for calculating the failure process of the Si-Ti-C-O fiber bonded ceramic material under three-point bend loading, where the statistic properties of the tensile strength obtained from the above Monte-Carlo simulation was taken into account. The calculated load-deflection response and failure processes were in quite good agreement with the experimental data. Furthermore, the discrepancy in the distribution of the strength calculated was found under tensile and three-point bend loading conditions;the larger Weibull shape parameter and the smaller average value in the tensile strength than in the flexural strength were successfully assessed through the calculations. Finally, the effect of the interlaminar shear strength on the strength and its distribution was discussed under bend loading.

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This paper deals with an interaction problem of two ellipsoidal inclusions under asymmetric uniaxial tension. The problem is solved on the superposition of two auxiliary loads;(i)biaxial tension and(ii)plane state of pure shear. These problems are formulated as a system of singular integral equations with Cauchy-type or logarithmic-type singularities, where the densities of the body forces distributed in the γ, θ, z directions are unknown functions. In order to satisfy the boundary conditions along the boundaries, the unknown functions are approximated by a linear combination of fundamental density functions and polynomials. The present method is found to yeild rapidly converging numerical results and smooth stress distributions along the boundaries. For hard inclusions(E_I/E_M>1), the interaction appears as a large compressive stress σ_n;however, the maximum tensile stress is almost independent of the interaction. For soft inclusions(E_I/E_M<1), the interaction appears as a large tensile stress σ_θ.

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This paper presents a simple method for structural analysis of honeycomb sandwich panel(HSP), which is used as light weight and high stiffness material. It is shown that the rigidity of honeycomb core is very influential to the stiffness of HSP when HSP is subjected to bending load, and elastic and plastic moduli of rigidity are given by honeycomb parameters such as cell size and cell wall thickness. Therefore the authors propose the finite element model for structural analysis of HSP, which can simulate the HSP deformed behavior without detailed hexagonal mesh. The analyses results given by the proposed element agree with the results of the experiment and the detailed meshing analyses. This element doesn't reduce the precision but significantly reduces the time for pre and post processes, and analyses.

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This paper analyzes elastic deformation properties of the blanket in offset printing due to a contact load of the impression(or plate)cylinder with the blanket cylinder, considering anisotropic properties and the laminated construction of the blanket. The two dimensional elastic theory is applied to solve the contact problem of the blanket and the numerical solution provides details of the contact pressure distribution, the deformation of the blanket, and the contact width of the blanket with the impression(or plate)cylinder. Influences of Young's moduli and thickness of each layer of the blanket on the contact pressure distribution and the deformation of the blanket, are examined by the theory. The experiments are carried out for measuring the contact pressure distribution and the deformation of the blanket and the calculated results are in fair agreement with those of experiment.

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In this paper, the authors describe a new method for determining the fringe order and the principal direction of birefringence from a single image. Using an elliptically polarized tricolored light and color image processing, the fringe order and the principal direction of birefringence are obtained from data of a color image obtained by a single shot. The theory of the proposed method and the entire experimental and analytical system are described. Then, a successful application of the method to 2-D photoelastic analysis is demonstrated. It is emphasized that this method can be applied to time-dependent phenomena, since multiple exposures are not necessary for sufficient data acquisition in the completion of stress analysis.

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Analytical and experimental analysis for tensile and compressive creep properties of fine and coarse-grained aluminium alloy, A3003P, used for plate-fin heat exchanger are presented for temperatures from 400°C to 600°C and stresses between 0.255 MPa and 6.370 MPa. Investigation for parameters' effect on the behaviour of the time-dependent flow of material was carried out. For analytical investigation, the grain-size mechanism was applied to both tension and compression creep tests. Creep-strain rate increases with increasing both temperature and stress, while decreasing with coarse grain size. For loading mode, experimental results showed lower creep strain in compression than in tension for all stresses investigated. Nevertheless, numerical analysis showed identical behaviour for both tension and compression. Good agreement was found between the experimentally determined creep strain and analytical predictions at lower stress levels. However, at higher stresses considerable deviations from the experimental results were recorded for the analytical findings. Though the grain-size mechanism is applicable in case of tension for pure aluminium, modification becomes necessary when compression is applied.

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By assuming that the crack velosity a can be expressed as a power function of the stress intensity K₁, a∝Kⁿ₁, the degradation of strength during proof test of ceramic materials was analyzed, and Weibull distributions both for residual strength S_r and fracture strength σ_F after proof testing were analytically formulated. The analytical results show that Weibull curve for the S_r has a slope of about n-2 at low failure probability levels(n;the proof test environments), and also show that the corresponding Weibull curve for the σ_F has a slope of about(n-2)(N+1)/(N-2)(N;the fracture test environments).

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The effect of water environment on delamination fatigue crack propagation behavior was investigated using unidirectional CFRP laminates made from Toray prepregs T800H/3900-2. T800H/3900-2 has toughened interlayer which is composed of epoxy resin and thermoplastic polyamide particles. Tests were carried out under mode II loading using end notched flexure specimens which were moisture-conditioned up to the saturated level. In the static tests, the value of the fracture toughness for the moisture-saturated specimen was slightly smaller than that for the dry specimen in air. In the fatigue tests, the crack propagation rate, da/dN, was expressed as a power-low function of the maximum energy release rate, G_{II max} in the region where da/dN>5×10^-10m/cycle. Below this region, there exists the threshold value of G_{II max}. The threshold value for the moisture-saturated specimen in water was smaller than that for the dry specimen in air. Glass transition temperatures were measured both in moisture-saturated state and in dry state using differential scanning calorimetry. The decrease in the glass transition temperature indicated the ductility increase of epoxy. Microscopic observation revealed that the ductility increase of the epoxy affected the morphology of the fracture surfaces under fatigue loading.

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It was shown that the fracture mode of a mixed-mode crack in a homogeneous ductile material changes from mode I(opening)type to mode II(in-plane shear)type or vice versa by changing the loading type in the vicinity of a crack tip. The characteristics of this fracture mode change may depend not only on the loading type in the vicinity of a crack tip but also on the brittle/ductile property of a material. From this point of view, the fracture experiments of the specimens with an inclined crack made up by using acryl resin and aluminum alloy are carried out, in the present study, under tensile type and shearing type external loads. It is confirmed first through the experiments that the different fracture modes can be realized between the specimens of above two materials even under the same loading type in the vicinity of a crack tip. Moreover, the CED in an arbitrary direction is evaluated through the finite element analyses corresponding to the experiments. Finally, it is demonstrated that the effects of brittle/ductile property of a material and loading type in the vicinity of a crack tip on fracture mode of a mixed-mode crack can be grasped in a unified way by the criterion based on the CED in an arbitrary direction.

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The tips of the rodlets of rod cluster control assemblies(RCCAs) are exposed to extremely high neutron fluence in fuel assemblies. A high neutron fluence causes degradation of the control rod materials. In a pressurized water reactor(PWR) plant, increases in the outer diameters of the rodlets, induced by absorber swelling, and intergranular cracks at tips of rodlets were observed. First, mechanisms of cracking by material degradation due to neutron irradiation in nuclear reactors were given their definitions because they were previously not clearly defined. Then it was confirmed that the cause of intergranular cracks of RCCA rodlets was irradiation assisted mechanical cracking(IAMC). The cracks were induced by an increase in hoop strain due to the swelling of the absorber and a decrease in elongation due to neutron irradiation. Furthermore, investigations were carried out on the swelling mandrel test, because the structures and environments of the swelling mandrel test were similar to those of RCCA rodlets. As a result, it was found that the mechanism of the swelling mandrel test was not irradiation assisted stress corrosion cracking(IASCC) but IAMC. Also, intergranular cracks on the cladding tubes of RCCA rodlets could be induced at a very low strain rate.

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