Rubber composite materials consists of low molecular weight substances, high weight substances, particle-like, rod-like, flake-like reinforcing substances, and fibrous substances. They form complex high order structures and show non-linear composite effects. In this paper we classified each substance according to its composite effect, and presented a way to predict non-linear composite effects in multiple phase composite materials. In addition, assuming that fatigue and rupture of rubber composite materials are complex reactions consisted of six elementary reactions, we selected substances that controled fatigue and rupture phenomena and moreover we showed experimental examples about them.

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This paper is intended to discribe the photoviscoelastic technique which is known as one of the experimental viscoelastic stress and strain analyses. At first, the history and the present situation is discribed. Next, the fundamental equations for photoviscoelastic analysis are induced by use of two-dimensional linear photoviscoelastic theory. Prior to making a practical photoviscoelastic analysis, mechanical and optical characterizations of the materials are required. In other words, it is necessary to determine the time-and temperature dependent viscoelastic and photoviscoelastic coefficients. In this paper, the procedure for determination of photoviscoelastic coefficients is described in detail using epoxy resin. And, the practical photoviscoelastic analyses were carried out on two concrete problems. One is the analysis of a square plate with a central hole made of polyurethane resin, to which the non-proportional load is subjected at constant temperature. In this case, the axes of polarization of light, principal stress and principal strain do not coincide with each other. Another is the analysis of a epoxy strip which is subjected to quenching from both sides. This is so-called a thermo-viscoelastic problem, in which there is a large temperature change in the body.

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A draft on materials system design considered as synthesis is presented. Tow topics with respect to materials system design are discussed. One is concerned with the problem of definition of materials system design in the engineering design, another is concerned with the analogues between the materials system design and social system design. The former problem is discussed within the subjects such as process of engineering design, environment of engineering design, and object and mission of engineering design. In the discussions, it is suggested that the materials system design needs the synthesized function in the process of the design. The synthesized function stems from the combinations of various categories of design, i.e., material design and structural design which are of interest. However, it is a difficult problem to evaluate the effectiveness of synthesized function quantitatively. To meet this problem, the latter topic is reviewed, which corresponds to the analogues between materials system design and social system design. If the analogues can be found, it is expected that the effectiveness of synthesized function in the process of materials system design will be evaluated quantitatively with the application of the decision making procedure in the social system.

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A design technique to determine an optimum layout of structural continuum, which gives an absolute optimum of truss structures under alternative given loading and supporting conditions, is proposed by using a concept of Michell structures. The structural continuum is analyzed by the finite element method of a linear triangular element, in which obliquely crossing truss members are distributed uniformly and continuously. These members in each element are arranged into optimum directions by Davidon-Fletcher-Powell's method to minimize the weight of structural continuum subjected to the stress constraints, the allowable limits of which are different each other in tension and in compression. The technique is applied to determine the optimum layouts of truss which consists of two members and of cantilever structure under alternative loadings.

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This paper deals with a procedure to simulate the foaming process in RIM (Reaction Injection Molding). The process involves heat generation by chemical reaction, heat loss through the mold and local vaporization and condensation of the solvent that plays a blowing agent. In addition, the foaming pressure causes change in the condensation temperature of the solvent. To simulate this dynamic process, one dimensional cell model was proposed. Each cell contains a certain mass of the solvent, and the volume, temperature and the pressure of the solvent can be estimated by the quantity of heat which is generated and/or transferred in the cell, assuming that no pressure gradient exists and total of each cell's volume is constant. For a typical fast cure polyurethane RIM system, apparent density profiles were predicted theoretically, as well as chemical conversion, temperature and pressure profiles. An experimental run was carried out and the results were compared with the theoretical values. Rather good agreement between them was obtained, considering that the number of material and process parameters were many and no adjusting parameter was introduced. The procedure presented here can be usefull to developement of materials and process for RIM.

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The dependences of temperature on transverse low cycle fatigue strength of CFRP are presented in this paper, where the experimental results of low cycle fatigue were shown at various temperatures for unidirectional CFRP and epoxy resin. The results obtained are summarized as follows: (1) The transverse low cycle fatigue strength of CFRP showed remarkable dependence on temperature in the same manner as the low cycle fatigue strength of the matrix. (2) The low cycle fatigue strength F_F(Nf,T) of CFRP and the matrix against the number of cycle to failure Nf at various temperatures T can be estimated by F_F(Nf,T)=[Fs(T)] mean・ {1-α(T)logNf}　where, [Fs(T)] mean is the mean value of static strength. The factor α(T) of the CFRP are in good agreement with that of the matrix. (3) It is recognized from the experiment that the mechanical property of CFRP in the cyclic load condition has a analogy to the viscoelastic behaviors of epoxy resin used as the matrix at T=140℃and 160℃.

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Optimum design method of sandwich beam with required flexural stiffness is discussed in this paper. The calculated results of minimum weight design and minimum cost design using actual data on CFRP, GFRP, KFRP (Kevlar/epoxy), resin, and steel are shown, and it is found that minimum weight design is performed at the considerable sacrifice of the cost and minimum cost design is performed at the considerable sacrifice of the weight. A proposal for optimum design method with the consideration of both weight and cost is drawn. The design criterion is derived from the assumption that the rate of increase in weight or cost is nearly equal to the rate of decrease in cost or weight at the optimum design solution for components to be designed in cosideration of weight and cost.

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A large residual stress due to the non-uniformity of temperature in the cooling process during its molding may develop inside the thermosetting-resin which has a two-dimensional spread. And, when there is a temperature difference on both surfaces in contact with the metal die, not only a residual stress but also a large warp is produced in the molding. This present paper discusses the effect of viscoelastic behavior on residual stress and deformation of thermosetting-resin strip constrained warp with metal die by single-side quenching. The viscoelastic behavior of thermosetting-resin was expressed by simple mathematics including two modul in the range of glassy state and rubbery state, glass transition temperature and time-temperature equivalent factor. The residual stress and deformation by quenching was calculated by the fundamental equations derived from the theory of linear-viscoelasticity. And the effect of viscoelastic behavior on residual stress and deformation of this quenched strip was discussed.

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Flexural properties of moldings made by RIM (Reaction Injection Molding), which are structual foams consisting of high density skin and low density core, were investigated by three-point bending tests. Two failure modes were observed in bending tests of the moldings made by RIM, and they are classified as follows according to the density ratio of skin layer to core layer. (1) The opposite side of the skin layer to which load was subjected was failed by tensile stress. (2) The same side of the skin layer to which load was subjected was failed by compressive stress, causing Wrinkling buckling. Then, the conventional composite beam theory was applied to the former failure mode and Hoff's buckling theory to the latter, and equations were derived to predict the flexural properties of the structual foams which involved buckling from the flexural properties of solid construction. In addition, it has been shown that there exists the density distribution that maximize the flexural strength of the moldings made by RIM with the given overall density. The results obtained here should be useful to the optimum structural design of moldings made by RIM.

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