@article{huang_yang_zhang_yuan_jiang_2015, title={Direct Measurement of Opening Mode Stress Intensity Factors Using Flexoelectric Strain Gradient Sensors}, volume={55}, ISSN={["1741-2765"]}, DOI={10.1007/s11340-014-9914-y}, number={2}, journal={EXPERIMENTAL MECHANICS}, author={Huang, Wenbin and Yang, Shaorui and Zhang, Ningyi and Yuan, Fuh-Gwo and Jiang, Xiaoning}, year={2015}, month={Feb}, pages={313–320} }
 @article{huang_yang_zhang_yuan_jiang_2014, title={Cracks Monitoring and Characterization Using Ba0.64Sr0.36TiO3 Flexoelectric Strain Gradient Sensors}, volume={9061}, ISSN={["0277-786X"]}, DOI={10.1117/12.2045166}, abstractNote={This paper presents a new method for monitoring and characterizing cracks using Ba0.64Sr0.36TiO3 flexoelectric strain gradient sensors. Firstly, strain gradient field around the mixed mode asymptotic crack tip was analyzed, followed by the derivation of induced flexoelectric polarization in the strain gradient sensors attached in the vicinity of a crack tip. It was found that the flexoelectric polarization of the sensor can be expressed as a function of the stress intensity factors of crack and relative coordinates between the sensor and crack. Given the information of the crack size, further analysis demonstrates that the location of the crack can be traced through the calculation based on flexoelectric outputs of the distributed sensors. A specimen with Mode-I crack was then prepared with two strain gradient sensors (4.7 mm × 0.9 mm × 0.3 mm) attached close to the crack tip to verify the analytical model for detection of cracks. The experimental results yield accurate location of the crack, confirming that flexoelectric strain gradient sensing can be a good avenue for monitoring cracks.}, journal={SENSORS AND SMART STRUCTURES TECHNOLOGIES FOR CIVIL, MECHANICAL, AND AEROSPACE SYSTEMS 2014}, author={Huang, Wenbin and Yang, Shaorui and Zhang, Ningyi and Yuan, Fuh-Gwo and Jiang, Xiaoning}, year={2014} }
 @article{yan_huang_kwon_yang_jiang_yuan_2013, title={A sensor for the direct measurement of curvature based on flexoelectricity}, volume={22}, ISSN={["1361-665X"]}, DOI={10.1088/0964-1726/22/8/085016}, abstractNote={A direct curvature sensing measurement based on the flexoelectricity of Ba0.64Sr0.36TiO3 (BST) material through electromechanical coupling is proposed and developed in this paper. The curvature sensing was demonstrated in four point bending tests of a beam with bonded BST curvature sensors under different applied loads with low time-harmonic frequencies from 0.5 to 3 Hz. A shear lag concept which describes the efficiency of the loading transfer from the epoxy bonding layer was taken into account in extracting the actual curvature from the sensor measurement. A finite element analysis has been performed to estimate the curvature transfer efficiency and the bonding layer thickness is found to be a critical parameter in determining the curvature transfer. Experimental results showed a good linearity of charge output dependence on curvature inputs in a limited frequency range and showed a curvature sensitivity of 30.78 pC m, in comparison with 32.48 pC m from theoretical predictions. Using the measured curvature, the bending stiffness of the beam was then obtained from the experimentally obtained moment–curvature curve. This work demonstrated that the flexoelectric BST sensor provides a direct curvature measurement instead of using a traditional strain gage sensor through interpolation, and thus offers an important avenue for on-line and in situ structural health monitoring.}, number={8}, journal={SMART MATERIALS AND STRUCTURES}, author={Yan, Xiang and Huang, Wenbin and Kwon, Seol Ryung and Yang, Shaorui and Jiang, Xiaoning and Yuan, Fuh-Gwo}, year={2013}, month={Aug} }
 @article{yan_huang_kwon_yang_jiang_yuan_2013, title={Design of a curvature sensor using a flexoelectric material}, volume={8692}, ISSN={["1996-756X"]}, DOI={10.1117/12.2009941}, abstractNote={A curvature sensor based on flexoelectricity using Ba0.64Sr0.36TiO3 (BST) material is proposed and developed in this paper. The working principle of the sensor is based on the flexoelectricity, exhibiting coupling between mechanical strain gradient and electric polarization. A BST curvature sensor is lab prepared using a conventional solid state processing method. The curvature sensing is demonstrated in four point bending tests of the beam under harmonic loads. BST sensors are attached on both side surfaces of an aluminum beam, located symmetrically with respect to its neutral axis. Analyses have shown that the epoxy bonding layer plays a critical role for curvature transfer. Consequently a shear lag effect is taken into account for extracting actual curvature from the sensor measurement. Experimental results demonstrated good linearity from the charge outputs under the frequencies tests and showed a sensor sensitivity of 30.78pC•m in comparison with 32.48pC•m from theoretical prediction. The BST sensor provides a direct curvature measure instead of using traditional strain gage through interpolation and may offer an optional avenue for on-line and in-situ structural health monitoring.}, journal={SENSORS AND SMART STRUCTURES TECHNOLOGIES FOR CIVIL, MECHANICAL, AND AEROSPACE SYSTEMS 2013}, author={Yan, X. and Huang, W. B. and Kwon, S. R. and Yang, S. R. and Jiang, X. N. and Yuan, F. G.}, year={2013} }
 @article{yang_seelecke_2009, title={FE analysis of SMA-based bio-inspired bone-joint system}, volume={18}, ISSN={["0964-1726"]}, DOI={10.1088/0964-1726/18/10/104020}, abstractNote={This paper presents the finite element (FE) analysis of a bio-inspired bone–joint system. Motivated by the BATMAV project, which aims at the development of a micro-air-vehicle platform that implements bat-like flapping flight capabilities, we study the actuation of a typical elbow joint, using shape memory alloy (SMA) in a dual manner. Micro-scale martensitic SMA wires are used as ‘metal muscles’ to actuate a system of humerus, elbow joint and radius, in concert with austenitic wires, which operate as flexible joints due to their superelastic character. For the FE analysis, the humerus and radius are modeled as standard elastic beams, while the elbow joint and muscle wires use the Achenbach–Muller–Seelecke SMA model as beams and cable elements, respectively. The particular focus of the paper is on the implementation of the above SMA model in COMSOL.}, number={10}, journal={SMART MATERIALS & STRUCTURES}, author={Yang, S. and Seelecke, S.}, year={2009}, month={Oct} }
 @article{yang_yuan_2005, title={Transient wave propagation of isotropic plates using a higher-order plate theory}, volume={42}, ISSN={["1879-2146"]}, DOI={10.1016/j.ijsolstr.2004.12.014}, abstractNote={Transient wave propagation of isotropic thin plates using a higher-order plate theory is presented in this paper. The aim of this investigation is to assess the applicability of the higher-order plate theory in describing wave behavior of isotropic plates at higher frequencies. Both extensional and flexural waves are considered. A complete discussion of dispersion of isotropic plates is first investigated. All the wave modes and wave behavior for each mode in the low and high-frequency ranges are provided in detail. Using the dispersion relation and integral transforms, exact integral solutions for an isotropic plate subjected to pure impulse load and a number of wave excitations based on the higher-order theory are obtained and asymptotic solutions which highlight the physics of waves are also presented. The axisymmetric three-dimensional analytical solutions of linear wave equations are also presented for comparison. Results show that the higher-order theory can predict the wave behavior closely with exact linear wave solutions at higher frequencies.}, number={14}, journal={INTERNATIONAL JOURNAL OF SOLIDS AND STRUCTURES}, author={Yang, S and Yuan, FG}, year={2005}, month={Jul}, pages={4115–4153} }
 @article{yuan_yang_yang_2003, title={Three-dimensional Green's functions for composite laminates}, volume={40}, ISSN={["1879-2146"]}, DOI={10.1016/S0020-7683(02)00545-0}, abstractNote={The three-dimensional Green’s functions due to a point force in composite laminates are solved by using generalized Stroh formalism and two-dimensional Fourier transforms. Each layer of the composite is generally anisotropic and linearly elastic. The interfaces between different layers are parallel to the top and bottom surfaces of the composite and are perfectly bonded. The Green’s functions of point forces applied at the free surface, interface, and in the interior of a layer are derived in the Fourier transformed domain respectively. The surfaces are imposed by a proportional spring-type boundary condition. The spring-type condition may be reduced to traction-free, displacement-fixed, and mirror-symmetric conditions. Numerical examples are given to demonstrate the validity and elegance of the present formulation of three-dimensional point-force Green’s functions for composite laminates.}, number={2}, journal={INTERNATIONAL JOURNAL OF SOLIDS AND STRUCTURES}, author={Yuan, FG and Yang, S and Yang, B}, year={2003}, month={Jan}, pages={331–342} }
 @article{yuan_yang_2002, title={Crack-tip fields in anisotropic shells}, volume={113}, ISSN={["0376-9429"]}, DOI={10.1023/A:1014245311814}, number={4}, journal={INTERNATIONAL JOURNAL OF FRACTURE}, author={Yuan, FG and Yang, S}, year={2002}, month={Feb}, pages={309–326} }
 @article{yuan_yang_2001, title={Fracture behavior of stitched warp-knit fabric composites}, volume={108}, ISSN={["0376-9429"]}, DOI={10.1023/a:1007610908503}, number={1}, journal={INTERNATIONAL JOURNAL OF FRACTURE}, author={Yuan, FG and Yang, S}, year={2001}, month={Mar}, pages={73–94} }
 @article{yuan_yang_2000, title={Asymptotic crack-tip fields in an anisotropic plate subjected to bending, twisting moments and transverse shear loads}, volume={60}, ISSN={["1879-1050"]}, DOI={10.1016/S0266-3538(00)00043-9}, abstractNote={Asymptotic crack-tip fields, including the effect of transverse shear deformation, in an anisotropic plate under bending, twisting moments and transverse shear loads are presented. By utilizing the Hellinger–Reissner variational principle, the equilibrium equations and generalized strain/stress relations for anisotropic Reissner plate theory are obtained. Assuming the displacement and stress resultant are in a separation-of-variable form, it is found that, for the first two order terms of the asymptotic solution, the equations governing crack-tip fields of anisotropic plate bending are analogous to those governing plane stress and anti-plane deformation of anisotropic elasticity. Thus the Stroh formalism can be used to characterize the crack-tip fields of the anisotropic plate up to the second-order term and the energy release rate can be expressed in a very compact form in terms of stress intensity factors and the Barnett–Lothe tensor L. The first three order terms of the crack-tip displacement and stress fields including the “T-stresses” in bending and transverse shear are presented. The displacement and stress fields near crack tips in isotropic plates up to the second order are also provided. The energy release rate expression for orthotropic and isotropic plates is also derived. The solutions of anisotropic plates by a combination of in-plane and bending loads is also investigated. The expression of the path-independent integral, J, in terms of the generalized stress and strain is derived which is useful to calculate the value of stress intensity factors. Finally, on the basis of the asymptotic solutions, methods of determining stress intensity factors and T-stresses are proposed.}, number={12-13}, journal={COMPOSITES SCIENCE AND TECHNOLOGY}, author={Yuan, FG and Yang, S}, year={2000}, pages={2489–2502} }
 @article{yuan_yang_2000, title={Crack-tip fields for matrix cracks between dissimilar elastic and creeping materials}, volume={103}, DOI={10.1023/A:1007620114187}, number={4}, journal={International Journal of Fracture}, author={Yuan, F. G. and Yang, S.}, year={2000}, pages={327–360} }
 @article{yang_yuan_2000, title={Determination and representation of the stress coefficient terms by path-independent integrals in anisotropic cracked solids}, volume={101}, ISSN={["0376-9429"]}, DOI={10.1023/A:1007639126484}, number={4}, journal={INTERNATIONAL JOURNAL OF FRACTURE}, author={Yang, S and Yuan, FG}, year={2000}, month={Feb}, pages={291–319} }
 @article{yang_yuan_2000, title={Kinked crack in anisotropic bodies}, volume={37}, ISSN={["1879-2146"]}, DOI={10.1016/S0020-7683(99)00222-X}, abstractNote={Solutions are presented for a crack kinking out of the crack plane in a generally anisotropic elastic body under two-dimensional deformation. Based on Stroh formalism, a system of singular integral equations governing the kinking crack with small kink length is given in a simple, straightforward form. The explicit expressions of the stress intensity factors, T-stresses, and energy release rates at the kinked crack tip are presented in terms of some nondimensional coefficients together with the stress intensity factors, T-stresses, and the coefficients of the third term acting on the main crack tip prior to crack kinking. The nondimensional coefficients depend on kink angle and material constants, but not on kink length. The energy release rate ratio which may characterize the competition along different crack growth directions is provided. The role of T-stresses and the third-term applied at the main crack field are determined which can be significant in the kinking and the stability of the kinked crack. Based on the energy release rate fracture criterion, the stability condition of the kinked crack is derived. The influences of anisotropy and loading mixity on the implications of crack kinking behavior is also given. The results for monoclinic materials with symmetry plane at x3=0 are derived from general results. Numerical results for the stress intensity factors, T-stresses at the kinked acrack tip and the energy release rate ratio for some special cases are provided. The dimensionless coefficients for crack kinking of orthotropic materials at the right angle to the main crack plane are tabulated.}, number={45}, journal={INTERNATIONAL JOURNAL OF SOLIDS AND STRUCTURES}, author={Yang, S and Yuan, FG}, year={2000}, month={Nov}, pages={6635–6682} }
 @article{yuan_yang_1997, title={Crack-tip fields in elastic-plastic material under plane stress mode I loading}, volume={85}, ISSN={["0376-9429"]}, DOI={10.1023/A:1007361116709}, number={2}, journal={INTERNATIONAL JOURNAL OF FRACTURE}, author={Yuan, FG and Yang, S}, year={1997}, pages={131–155} }
 @article{yuan_yang_1997, title={The curved interfacial crack between dissimilar isotropic solids}, volume={34}, ISSN={["0020-7683"]}, DOI={10.1016/S0020-7683(96)00049-2}, abstractNote={The paper examines analytically the role of curvature on the stress distribution of a curved interfacial crack between dissimilar isotropic solids. The crack-tip fields under in-plane and antiplane shear loading are studied, respectively. Using an asymptotic expansion of the circular interface geometry, the asymptotic solutions of the stress and displacement fields in the vicinity of the curved crack tip derived from modified stress functions is obtained. The eigenfunctions associated with the eigenvalues λ for the curved crack consist of not only rλ terms, but also rλ+1, rλ+2, … terms. In some cases, the terms rλ+1(ln r), rλ+2(ln r), etc. may also exist. Two examples, frictionless contact near the circular crack-tip under in-plane loading and circular interfacial crack subject to antiplane shear loading, are derived in a closed-form asymptotic solution to elucidate the curvature effect. The case of fully open interfacial crack is also briefly described. Comparing the eigenfunction solutions of straight interfaces, the curvature effect enters the stress fields from the third-order term of the asymptotic solution for both cases. The condition for the existence of the r½(lnr) term in the circular interfacial crack with frictionless contact is presented explicitly.}, number={6}, journal={INTERNATIONAL JOURNAL OF SOLIDS AND STRUCTURES}, author={Yuan, FG and Yang, S}, year={1997}, month={Feb}, pages={641–660} }