Recently many new detached wooden houses are produced using pre-cut processing（ described later）. In order to evaluate the structural performance of a wooden house, information on the frame and design information on the joints are required. This information is created as three-dimensional information in CAD （Computer Aided Design） data for pre-cut processing and has an extremely high affinity for structural analysis. At present two-story wooden houses are just only required to calculate the amount of wall. However, if three-dimensional information at the time of pre-cutting can be utilized in structural design, it is possible to produce wooden houses with structurally more structural safety. We focus on the CAD information for wooden houses and introduce the contents of the research which examined the method to cooperate with the structural performance evaluation.
Epoxy monoliths with a co-continuous porous structure were produced by a thermosetting reaction using combinations of 4 kinds of epoxy resins, 9 kinds of diamine curing agents, and 2 kinds of porogens（ pore forming agents）, and applied to dissimilar materials bonding between metals and engineering plastics. An epoxy monolith was prepared on a stainless or copper plate, and a polycarbonate or poly（phenylene sulfide） plate was thermally welded to prepare a bonding test piece. The heat resistance of the epoxy monolith bonding systems used in this study was evaluated from the results of the tensile shear test before and after heat treatment. In addition, the thermogravimetric analysis of the monolith materials revealed the thermal decomposition behavior of the cured epoxy. Based on these results, the effects of the structure and the number of functional groups of the epoxy resins and the diamine curing agents on the porous structure, bonding strength, and heat resistance of the epoxy monoliths were discussed.
The craze has porous structure consisting of fibrils（ fiber bundles） and voids（ pores） with a diameter of several tens of nanometers. Craze differs from crack. In previous work, to control craze formation, we have succeeded that crazing film consists of repeated porous phase and non-porous phase. This porous phase has specific properties. For craze, the temperature required to begin void disappearance was lower than the melting point. There are many reports that estimate this phenomenon due to the melting of polymers or contribution of internal residual stress. On the other hand, the behavior is different from an ordinary thermal relaxation phenomenon. Therefore, in this paper, the phenomenon that void in craze is scale downed and disappear, is defined as“ healing”. It is thought that generation and progression of the healing is caused by interfacial free energy as a driving force. In this study, we reported the balance between“ Laplace-pressure” which is a self-shrinking force acting on void in craze and the widening force such as an external tensile load. From the stress-strain curve, a bending point was confirmed only the crazed film separately from the yield point. The stress at the bending point decreased with an increase in specimen sample temperature. On the other hand, the temperature dependency of strain had not been observed. Based on the above result, it was shown that the appearance of the bending point was a characteristic behavior derived from their voids. In addition, it was revealed that an inflection point in the S-S curve was determined in response to the balance between the void property in craze and an original mechanical strength of raw polymer as used.
Second-generation acrylic adhesives（ SGA） are room temperature curing adhesives. Thus, curing temperature is generally set as the ambient temperature. In this study, the effect of curing temperature on strength and fracture toughness were investigated. In the shear test, the different fracture surface was observed depending on the curing temperature, whereas no significant change in strength due to the curing temperature was observed. However, microscopic observations using AFM confirmed that the sea-island structure changed due to the curing temperature, as well as the physical properties of the material via the tensile test changed. The DCB test revealed that these changes had a significant effect on fracture toughness. Although the fracture toughness with the specimen cured at low temperature did not recover by post-curing, it improved significantly with the specimen cured at high temperature.