In the several departments of engineering, the measuring contact stress distribution and the area is very important. The rapid improvement of electronics and computer techniques becomes possible to measure the contact stress distribution between the optional bodies. In this paper, the recent advance of techniques measuring contact stress distributions is presented. On the presented techniques, the remarkable features and several points to improve are appeared.

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Recently, the concept of artificial intelligence (AI) has been widely utilized for engineering problem solving. One approach is to make computers more intelligent, and this can be realized by using AI oriented computer languages including LISP, PROLOG and Smalltalk. This paper deals with the basic considerations on the application of Smalltalk to structural design. Smalltalk is one of object oriented languages. Objects in Smalltalk have hierarchical structures named “class” and return some results by receiving messages named “methods”. The class “SteelBar”　is defined and the stress, strain and elongation of a bar subject to tensile loading are obtained by adding some methods to our system, or an intelligent image.

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The frequency analysis is applied to the acoustic emission generated in composite materials during fatigue fracture process. The method determining the dominant frequency for the damage of constituent elements in these materials is described. The dominant frequency in three stages of the fatigue crack growth and a usefulness of frequency analysis in researches of fatigue fracture mechanisms are discussed in this paper.

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This paper intended to describe a simplified optical method based on photoviscoelasticity proposed for measuring the residual stress in two-dimensional thermosetting resin molding generated by cooling. The fundamental equation for calculating the residual stress from the residual birefringence and deformation in two-dimensional photoviscoelastic body by cooling was derived using the linear photoviscoelastic theory. The practical analyses were carried out on three characteristic problems, which are the analyses of the residual stresses in a strip, plate and disk made of epoxy resin by rapid cooling. These residual stresses were measured by two methods i. e., the proposed simplified optical method and the well-known layer removal method. The effectiveness of the simplified optical method could be assessed by discussing and comparing the results obtained by the two methods.

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The influence of laminate constitution on impact behavior of C/A hybrid FRP were investigated through impact test by using the electronic measuring Charpy testing machine. The specimens are C/A hybrid unidirectional FRP laminates in which the volume ratio of CFRP to AFRP is 50% to 50% and in which the thickness of repeating unit of CFRP and AFRP is varied. The load-deflection curves of hybrid FRP on impact test are similar to that on static bending test. The flexural strength and the energy to peak force of hybrid FRP are maximized at the laminate constitution with which the fracture mode changes. All types of laminates which had CFRP layer on the surface and two types having thin AFRP layer on the surface fractured from the compressive surface, and the types having thick AFRP layer on the surface fractured from the tensile surface. The strength of compressive surface fracture was predicted by using the laminate theory based on the compressive strength of CFRP, and the strength of tensile surface fracture was predicted by using the same theory based on the tensile strength of AFRP.

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In order to characterize the growth behavior of fatigue cracks propagationg along the weld interface, a series of fatigue crack growth tests was conducted on center notched plate specimens fabricated from SUS304/SUS304 fricion welded butt joint of 40mm in diameter. Results indicated that cracks grew faster along the interface at the inner part of the joint than those of the base material, presummably depending on the tensile residual stress introduced during thermal hysteresis following friction welding process and on structural discontinuites at weld interface. Furthermore, retardation of crack growth rate of the joint specimen due to overload application was not so distinct in comparison with that of the base material. This suggests that the weld interface has higher flow resistance than the base material.

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CFRP made from “TORAYCA”T800H/3900 series prepreg showed extremely high impact resistant properties because of their superior toughness. From the study of interlaminar fracture toughness, testing method of edge delamination strength (EDS) was found to be simpler than that of G_ⅠC and G_Ⅱ. Further more, EDS was also found to be more effective to evaluate CFRP mechanical properties, such as compressive strength after impact (CAI).

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The loss tangent of the composite is measured but not systematically, for the reason of difficulties in the method of measurement and the vagueness in the measured values when including cracks. Recently, the direct measurement is possible to make use of the micro-computer and the A/D-converter for variation of stress-strain loop during fatigue without the vibration-and torsional-method. In this paper, some conclusions are reported from the measurements of loss tangent for the composites during fatigue as follows: 1) The temperature rise of the specimen is caused by the accumulated energy due to a half of area in the hysteresis loop during fatigue. 2) The change in loss tangent with temperature depends on composite structure. 3) The increase of loss tangent in the cloth FRP is larger than in other composites during fatigue: this depending on differences in composite structure.

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As for metal matrix composite, many kinds of reinforcing material such as ceramic fibers and whiskers have been under research and development. However these fibers and whiskers are still very expensive and the manufacturing method to disperse these reinforcing materials uniformly in the metal is still required intensive labor and technique. This paper reports and investigation of bars and plates of silicon-carbide reinforced aluminum alloys prepared by hot extrusion forming of the mixture of siliconcarbide powder and A6061 atomized aluminum powder. As cross-section of extruded bar, round, pipe, H-type, T-type, star shape etc are available by selecting the die if required of special shapes. Properties such as cold and hot tensile compressive strength, wear resistance test and many kinds application for industrial parts are discussed.

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