著者

髙井 直樹 元木 信弥 山崎 友裕

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集A編 (ISSN:18848338)

巻号頁・発行日

vol.79, no.807, pp.1632-1647, 2013 (Released:2013-11-25)

参考文献数

9

被引用文献数

1

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The effects of applied stresses on dynamic characteristics of piezoelectric ceramics are analyzed based on the nonlinear electroelastic theory. Piezoelectric ceramics are used in many electric devices as functional elements, where mechanical constraint is usually applied. Estimation of piezoelectric properties under applied stresses is important in designing the devices. However, applied stresses cannot be considered in the basic equations in the linear piezoelectric theory, and the effects of the applied stresses cannot be predicted. In this study, we introduce additional terms related to the dissipation effects, specifically, electric conduction and internal viscosity resistance, and nonlinearity of elastic properties into electroelastic theory. As well, considered nonlinear effects are elastic, piezoelectric and dielectric constants up to 3rd order. Frequency dependence of admittance of PZT disks is measured under applied compressions, showing that applied stresses have certain influences on either of thickness and radial vibrations of PZT. Assuming proper material constants, experimental results can be well explained by the nonlinear electroelastic theory.

著者

斉藤 一哉 野島 武敏

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集A編 (ISSN:18848338)

巻号頁・発行日

vol.78, no.787, pp.324-335, 2012 (Released:2012-03-25)

参考文献数

7

被引用文献数

2 3

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This study illustrates a new strategy to fabricate arbitrary cross-section honeycombs. These types of honeycombs are usually manufactured from normal flat honeycombs by curving or carving, but the proposed method enables us to construct objective shaped honeycombs directly. We first introduce the concept of the kirigami honeycomb, which is made from single flat sheets and has periodical slits resembling kirigami (Japanese art of study folding and cutting). In previous studies, honeycombs having various shapes, including tapered and aerofoil honeycombs, were made using this method, and were realized by only changing folding line diagrams (FLDs). In this study, these 3D kirigami honeycombs are generalized by numerical parameters and fabricated using a newly proposed FLD design method, which enables us to draw the FLD of arbitrary cross-section honeycombs

著者

高野 敦 森永 洋次 井上 登志夫

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集A編 (ISSN:18848338)

巻号頁・発行日

vol.79, no.800, pp.455-462, 2013 (Released:2013-04-25)

参考文献数

15

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Methods of evaluating the one-sided tolerance limit (A- and B-basis values) of unbalanced sample sets are derived. The A- and B-basis values are statistically calculated numbers that respectively indicate that at least 99 and 90 percent of the population is expected to equal or exceed the statistically calculated value with a confidence of 95 percent, and they are often used as strength tolerance limits in aerospace designs. The A- and B-basis values tend to be underestimated when the sample size is small and the conventional methods are used. Our novel methods improve the basis values by combining multiple sample sets from normally (Gaussian) distributed populations. We extended analysis of variance (ANOVA) to evaluate the A- and B-basis values by using non-central t-distribution under the condition of equality of variances. In addition, we derive coefficients for the basis values under the condition of non-equality of variances by using a Monte-Carlo method. Numerical examples show that both methods, i.e., equality and non-equality of variance cases, increase the A- and B-basis values.

著者

松田 伸也 黄木 景二

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集A編 (ISSN:18848338)

巻号頁・発行日

vol.78, no.790, pp.912-922, 2012 (Released:2012-06-25)

参考文献数

28

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This paper presents a probabilistic model for predicting the constant fatigue life (CFL) diagrams for ceramics. First, a unified probabilistic delayed-fracture (PDF) model was proposed on the basis of the slow crack growth (SCG) concept in conjunction with the two-parameter Weibull distribution. Second, probabilistic CFL diagrams for effective volume Veff, effective loading time teffNf, fracture probability F and stress ratio R were obtained using the PDF model. The probabilistic CFL diagram was then related with the modified Goodman's diagram. Third, the unified strength parameters associated with the PDF model were determined using the experiment data of Si3N4 subjected to rotating bending. The stress amplitude - the number of cycles to failure curves were then predicted for R=-1 and 0 and various values of F. Moreover, the probabilistic CFL diagrams for various values of Veff and teffNf at F were depicted using the unified strength parameters. The validity of the present model was confirmed through the comparison of the predicted CFL diagrams with the experiment data.

著者

山東 篤

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集A編 (ISSN:18848338)

巻号頁・発行日

vol.77, no.776, pp.600-609, 2011 (Released:2011-04-25)

参考文献数

9

被引用文献数

1 2

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The interactive terms in the mesh superposition method are calculated approximately because the integrand has a discontinuity along the mesh lines in a superimposed global mesh. In this paper, the accurate numerical integration technique for a discontinuous integrand by the Delaunay triangulation is proposed. Integral ranges including discontinuous integrands are divided into triangles only with a continuum integrand. The exact solution is sum of the integral values calculated in all triangles. Appropriate triangle edges can be regenerated by the swapping algorithm even though generated triangles contain the inappropriate boundary lines which bring about a discontinuity. A comparison of the accuracy of numerical integration between the proposed technique and conventional approximate means and an application to a sensitivity calculation are investigated in the first example. The second example illustrates the swapping algorithm for the adjustment of generated triangles.

著者

高木 知弘

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集A編 (ISSN:18848338)

巻号頁・発行日

vol.77, no.783, pp.1840-1850, 2011 (Released:2011-11-25)

参考文献数

20

被引用文献数

1

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Phase-field topology optimization model which aims the maximum rigidity of mechanical structure has been developed and its fundamental performances have been evaluated by performing two-dimensional cantilever simulation. Here, the effects of interface thickness, initial morphology and solid volume fraction on the final morphologies and rigidity have been investigated. As a result, it has been confirmed that the thin interface thickness produces the high rigidity of the structure with small computational cost. Furthermore, the developed model enabled us to maximize the rigidity of mechanical structure stably and easily and the initial morphology dependencies of final morphology were relatively small.

著者

荒尾 与史彦 小柳 潤 武田 真一 宇都宮 真 川田 宏之

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集A編 (ISSN:18848338)

巻号頁・発行日

vol.77, no.776, pp.619-628, 2011 (Released:2011-04-25)

参考文献数

17

被引用文献数

7 8

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Strict geometrical stability is required for the precise structures like telescopes. Unpredictable out-of-plane deformation is a serious problem when we use CFRP (Carbon Fiber Reinforced Plastic) laminate to the precise structure. This out-of plane deformation of symmetrical CFRP laminate mainly arise from combination effects of ply angle misalignment and temperature change. We discussed here is effective stacking sequence of CFRP laminate that mitigate the deformation caused by the ply angle misalignment. The analysis based on laminate theory was performed to calculate the thermal deformation. In this analysis, the random numbers were added to each layers as ply angle misalignments. The analytical results were obtained statistically by Monte Carlo method. Mohr's curvature circle was also incorporated to evaluate the deformation as P-V (peak to Valley) values. We performed the analysis with various stacking sequence. It was calculated that the symmetric cross-ply laminates deformed 10 times larger than the other quasi-symmetric laminates. In the case of the total ply number is less than 12, the stacking sequence in the laminate has a significant effects on the thermal deformation. However, if the total number ply number is more than 24, effect of stacking sequence on the thermal deformation becomes negligible. We also discussed the geometrical stability of CFRP mirror by considering unavoidable ply angle misalignment. It was presumed that the CFRP mirror can be used for wide range of wave length when the back structure was attached to CFRP laminates.