• Journal of Mechanical Science and Technology
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• v.18 no.9
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• pp.1582-1589
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• 2004

The dynamic response of an eccentric Griffith crack in functionally graded piezoelectric ceramic strip under anti-plane shear impact loading is ana lysed using integral transform method. Laplace transform and Fourier transform are used to reduce the problem to two pairs of dual integral equations, which are then expressed to Fredholm integral equations of the second kind. We assume that the properties of the functionally graded piezoelectric material vary continuously along the thickness. The impermeable crack boundary condition is adopted. Numerical values on the dynamic stress intensity factors are presented for the functionally graded piezoelectric material to show the dependence of the gradient of material properties and electric loadings.

• Journal of Mechanical Science and Technology
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• v.17 no.6
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• pp.854-859
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• 2003

In this paper, we examine the singular stresses and electric fields in a functionally graded piezoelectric ceramic strip containing an eccentric crack off the center line under anti-plane shear loading with the theory of linear piezoelectricity. It is assumed that the properties of the functionally graded piezoelectric ceramic strip vary continuously along the thickness. Fourier transforms are used to reduce the problem to the solution of two pairs of dual integral equations, which are then expressed to a Fredholm integral equation of the second kind. Numerical values on the stress intensity factor and the energy release rate are obtained.

• Journal of Mechanical Science and Technology
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• v.15 no.1
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• pp.21-25
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• 2001

We consider the problem of determining the singular stresses and electric fields in a piezoelectric ceramic strip containing a Griffith eccentric crack off the center line under anti-plane shear loading with the theory of linear piezoelectricity. Fourier transforms are used to reduce the problem to the solution of two pairs of dual integral equations, which are then expressed to a Fredholm integral equation of the second kind. Numerical values on the stress intensity factor and the energy release rate are obtained, and the influences of the electric fields for piezoelectric ceramics are discussed.

• Structural Engineering and Mechanics
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• v.19 no.4
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• pp.401-411
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• 2005

The influence of cracks on the elastic deflection and ultimate bearing capacity of eccentric thin-walled columns with both ends pinned was studied in this paper. First, a method was developed and applied to determine the elastic deflection of the eccentric thin-walled columns containing some model-I cracks. A trigonometric series solution of the elastic deflection equation was obtained by the Rayleigh-Ritz energy method. Compared with the solution presented in Okamura (1981), this solution meets the needs of compatibility of deformation and is useful for thin-walled columns. Second, a two-criteria approach to determine the stability factor ${\varphi}$ has been suggested and its analytical formula has been derived. Finally, as an example, box columns with a center through-wall crack were analyzed and calculated. The effects of cracks on both the maximum deflection and the stability coefficient ${\varphi}$ for various crack lengths or eccentricities were illustrated and discussed. The analytical and numerical results of tests on the columns show that the deflection increment caused by the cracks increases with increased crack length or eccentricity, and the critical transition crack length from yielding failure to fracture failure ${\xi}_c$ is found to decrease with an increase of the slenderness ratio or eccentricity.

• Journal of Welding and Joining
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• v.12 no.3
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• pp.90-100
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• 1994

In this study the fatigue crack growth behavior was investigated for the surface cracks in aluminum alloy A5083-O plate and its weldment. Several kinds of specimens were tested at room temperature. The Eccentric specimens(E1.0, E2.5) subjected to combined stresses(tension+bending) were tested and the welded specimens with weld toes(TOE1, TOE2) were tested in order to verify the method to consider the stress concentration such as weld toe. It was ascertained that the surface crack growth property in the weld toe could be predicted by the corrected Pang's equation proposed in this study.

• Structural Engineering and Mechanics
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• v.71 no.3
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• pp.211-221
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• 2019

To study the eccentric compression behavior of ultra-high performance fiber reinforced concrete (UHPFRC) columns, six UHPFRC columns and one high-strength concrete (HSC) column were tested. Variation parameters include load eccentricity, volume of steel fibers and stirrup ratio. The crack pattern, failure mode, bearing capacity, and deformation of the specimens were studied. The results showed that the UHPFRC columns had different failure modes. The large eccentric compression failure mode was the longitudinal tensile reinforcements yielded and many horizontal cracks appeared in the tension zone. The small eccentric compression failure mode was the longitudinal compressive reinforcements yielded and vertical cracks appeared in the compressive zone. Because of the bridging effect of steel fibers, the number of cracks significantly increased, and the width of cracks decreased. The load-deflection curves of the UHPFRC columns showed gradually descending without sudden dropping, indicating that the specimens had better deformation. The finite element (FE) analysis was performed to stimulate the damage process of the specimens with monotonic loading. The concrete damaged plasticity (CDP) model was adopted to characterize the behaviour of UHPFRC. The contribution of the UHPFRC tensile strength was considered in the bearing capacity, and the theoretical calculation formulas were derived. The theoretical calculation results were consistent with the test results. This research can provide the experimental and theoretical basis for UHPFRC columns in engineering applications.

• Structural Engineering and Mechanics
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• v.76 no.4
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• pp.541-550
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• 2020

As a new type of concrete material, basic magnesium sulfate cement concrete (BMSC) has the advantages, such as early strength, high strength, good toughness and crack resistance. However, it is unclear about the degradation of the mechanical properties of BMSC columns, which is exposed to the natural environment for several years. In order to apply this new concrete to practical engineering, six large-eccentricity compressive columns of BMSC were studied. The mechanical properties such as the crack propagation, failure morphology, lateral displacement and bearing capacity of BMSC column were studied. The results show that the degradation rate of ultimate load of BMSC column is from 6% to 7%. The degradation rate of the stiffness of the column is from 6% to 13%. With the increase of compressive strength of BMSC, the axial displacement and lateral displacement are gradually reduced. The calculation model of bearing capacity of the BMSC column under the large eccentric compression is proposed. This paper provides a reference for the application of BMSC columns in the civil engineering.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.7
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• pp.693-700
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• 2015

To estimate the fatigue crack propagation behavior of compact tension shear (CTS) specimen under mixed-mode loads, crack path prediction theories and Tanaka's equation were applied. The stress intensity factor at a newly created crack tip was calculated using a finite element method via ANSYS, and the crack path and crack increment were then obtained from the crack path prediction theories, Tanaka's equation, and the Paris' equation, which were preprogrammed in Microsoft Excel. A new method called the finite element crack tip updating method (FECTUM) was developed. In this method, the finite element method and Microsoft Excel are used to calculate the stress intensity factors and the crack path, respectively, at the crack tip per each crack increment. The developed FECTUM was applied to simulate the fatigue crack propagation of a single-edge notched bending (SENB) specimen under eccentric three-point bending loads. The results showed that the number of cycles to failure of the specimen obtained experimentally and numerically were in good agreement within an error range of less than 3%.

• Journal of Korean Tunnelling and Underground Space Association
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• v.9 no.3
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• pp.219-228
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• 2007

Scaled model tests were performed to explore the influence of eccentric load and lateral earth pressure on tunnel behavior and their results were verified through numerical analyses. As a method for reducing the eccentric load acting on tunnel, an eccentric supporting system (ESS) was proposed and its applicability was investigated. Experimental results showed that displacement decreased overall and the load inducing initial cracks increased as the eccentric supporting system was applied. The maximum eccentric vertical load which impacted the stability of tunnel was also increased. The test results on the influence of lateral earth pressure on tunnel behavior showed that the general aspect of displacement and crack growth changed significantly depending on the coefficient of lateral earth pressure. In addition, the weak zone In view of stability varied as well.

• Proceedings of the KSME Conference
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• 2001.11a
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• pp.22-26
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• 2001

In this paper, we examine the steady state dynamic electromechanical behavior of an eccentric Yoffe crack in a piezoelectric ceramic layer bonded between two orthotropic elastic layers under the combined anti-plane mechanical shear and in-plane electrical loadings. We adopted permeable crack face condition. Numerical values on the dynamic energy release rate are obtained. The initial crack propagation orientation for PZT-5H piezoceramic is also predicted by maximum energy release rate criterion.