Characterization of defects in carbon fiber-reinforced plastics by inverse heat conduction analysis using transfer matrix between layers

In this study, inverse analyses of the defects in carbon fiber-reinforced plastics (CFRPs) are performed using the transfer matrix approach. The material properties used in the calculation were obtained on the basis of mixture laws for epoxy resin and carbon fibers. The accuracy of the inverse analysis was confirmed by calculations employing numerical models of CFRP plates with PAN-based and pitch-based carbon fibers containing defects. The inverse analysis was conducted based on the temperature distribution of CFRP laminates with PAN-based carbon fibers, which was obtained by infrared measurements. The analyses successfully estimated the positions of defects, and the effectiveness of the transfer matrix method for CFRPs was demonstrated through the inverse analysis.     

Elucidation of fatigue characteristics and fracture mechanism of friction stir spot‐welded tension–shear joint steels

The fatigue life and fracture mechanism of friction stir spot welded tension–shear joints using 590‐MPa class steel as a base material under constant‐amplitude conditions were investigated with focus on welding dimension variations caused by tool wear. The fatigue limit of the friction stir spot welding (FSSW) joint used for this study is significantly low compared with the static tensile strength of the joint itself. It was clarified that the FSSW joint in this study exhibited two different failure morphologies regardless of the applied load level: base metal fracture and weld area fracture. Although the welding state changes due to the tool wear phenomenon that produce two types of fracture modes in relation to the welding rip diameter, they have no effect on the fatigue strength, regardless of the applied load.     

An overview of the Seikan tunnel project

The Seikan Tunnel, the survey and excavation of which were begun in 1946 and 1964, respectively, is an undersea accessway connecting the island of Honshu and Hokkaido, Japan. The main tunnel was completed in 1985. Final completion of the tunnel is scheduled for 1987. The total length of the tunnel is 53 850 m, running under the seabed; water depth reaches a maximum of 140 m at certain points. The tunnel as excavated with a minimum overburden of 100 m. This paper outlines the construction work on the Seikan Tunnel, including the background history to tunnel construction, the basic design (alignment, type of cross-section and undersea construction system chosen), the construction work (schedule and contract system for the undersea portion), the operation facilities (track, electrical facilities, drainage facilities, ventilation and fire prevention measures), and the financing.     

Aphananthe aspera kernel oil: A rich source of linoleic acid

The seed kernels ofAphananthe aspera Planch. yielded 50.8% of a pale yellow oil. The fatty acid composition determined by gas liquid chromatography was: 5.3% palmitic, 0.1% hexadecenoic, 3.0% stearic, 6.1% oleic, 85.1% linoleic, and 0.4% linolenic acids.     

Statistical Analysis of Mechanical‐Shock Fragility Test Results

The mechanical‐shock fragility testing methods applied to packaging and product designs according to Japan Industrial Standards Z 0119:2002 incur some problems related to statistical analysis. One such problem is that the applied shock levels are increased in steps. We cannot determine the true fragility values for each sample. This is called interval‐censored data. If the maximum level of non‐damaging shock is selected for each sample, the calculated average will be too small. Another problem is that the number of shocks is limited to a maximum of 5 or 6, so as to minimize the effect of the accumulated fatigue. Therefore, if we determine the considerably high first shock level, initial‐censored data are obtained by the failure of the product when subjected to the planned first shock. If we determine the considerably low final shock level, final‐censored data are obtained when the product has not been damaged by the application of the planned final shock. These problems make statistical analysis difficult. We therefore propose an improved analysis method for data including interval‐censored, initial‐censored, and final‐censored data, and provide examples in which the method is applied to the results of a drop test. The results of the examples show that the proposed method is practical and that the censored data yields errors and loss of accuracy for the statistics. Finally, by means of a comparison between the staircase method of ISO 7765‐1:1988 and the method of JIS Z 0119:2002, we analyse the advantages and disadvantages of the respective methods. Copyright © 2017 John Wiley & Sons, Ltd.     

Capacitive Type Gas Sensors

Current status of capacitive type gas sensor were reviewed in this paper. Although the number of publications on capacitive type sensors has been limited so far, capacitive type sensors have good prospects given that the capacitor structure is so simple enabling miniaturization and achieving high reliability and low cost. Among the reported capacitive type sensors, detection of gas based on a change in dielectric layer thickness is most promising. On this point of view, capacitive type CO₂ and NO sensors using depletion layer formed at p-n junction of oxide semiconductor were introduced in detail. In addition, commercial capacitive type sensors for monitoring CO₂ based on this principle were mentioned. CO₂ concentration in office can be successfully monitored by the developed capacitive type CO₂ sensor.     

Test method for enhanced mechanical shock fragility statistics accuracy

An optimum cushioning package, which is neither excessive nor inadequate, must be designed to ensure cushioning performance that maintains an acceptable failure rate during transportation while also minimizing packaging costs. For this purpose, statistics pertaining to transport hazards and product shock strength must be engaged. The proposed study presents a test method to enhance the statistical accuracy of mechanical shock fragility of products. Sample statistics are invariably unknown; hence, optimum test‐setting values cannot be determined at the beginning. The proposed test method has been devised for determining optimum test‐setting values of the (n + 1)th sample using statistics of n samples being tested. An improvement in the estimation accuracy of the variation coefficient for the critical‐velocity‐change test was confirmed via simulations performed using the proposed method. Optimization of the test‐setting value has also been experimentally confirmed. A comparison of histograms and statistics obtained using experimental results has demonstrated that the proposed method can better estimate distribution shapes compared with the simple method. An example of the application of experimental results to stress‐strength models has also been described. The observed result has a considerable influence on the design of cushioning packages, thereby demonstrating effectiveness of the proposed method.     

Improved transverse piezoelectric properties in {110}-oriented B-site acceptor doped PLZT (8/65/35) thin films

Superior piezoelectric properties of lead-based perovskite type solid solution systems such as PLZT, having compositions near morphotropic phase boundary (MPB) make them ideal candidates for MEMS. The dielectric and piezoelectric characteristics in such perovskite based thin films are related to their structure and texture. In this study, we report the influence of aliovalent B-site acceptor dopants (Fe³⁺, Cu²⁺ and Mn³⁺) on the structure, dielectric and piezoelectric properties of {110}- preferentially oriented PLZT (8/65/35) thin films. Thin films having a thickness of 2.0 µm were prepared on silicon substrates (111) Pt/Ti/SiO₂/Si by Sol-gel spin coating technique. The preferential crystallographic orientation and crystalline phase formation in the thin films were analysed by X-ray diffraction and Raman spectroscopy respectively. The improved transverse piezoelectric coefficient, e_31,f and electric field induced bipolar strain characteristics of the acceptor doped PLZT films have been correlated with their crystal structure. Mechanism for higher bipolar strain in Cu²⁺ and Mn³⁺ doped PLZT films have also been studied and are reported.     

Discriminability-based evaluation of transmission capability of tactile transmission systems

Tactile transmission systems deliver tactile information such as texture roughness to operators of robotic systems. Such systems are typically composed of tactile sensors that sense the physical characteristics of textures and tactile displays that present tactile stimuli to operators. One problem associated with tactile transmission systems is that when the system has a bottleneck, it is difficult to identify whether the tactile sensor, tactile display, or perceptual ability of the user is the cause because they have different performance criteria. To solve this problem, this study established an evaluation method that uses the discriminability index as an evaluation criterion. The method lets tactile sensors, displays, and human tactile perception be assessed in terms of the ability to transmit physical quantities; the same criterion is used for all three possible causes so that their abilities can be directly compared. The developed method was applied to a tactile-roughness transmission system (Okamoto et?al. 2009), and its tactile sensor was identified as the bottleneck of the system.