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Yoshinobu Tanigawa - One of the best experts on this subject based on the ideXlab platform.

  • deriving the system of fundamental equations for three dimensional thermoelastic field with Nonhomogeneous Material properties and its application to a thick plate
    Jsme International Journal Series A-solid Mechanics and Material Engineering, 2000
    Co-Authors: Yoshinobu Tanigawa, Hiroyuki Morishita, Shigeo Ogaki
    Abstract:

    In this study, an analytical method for deriving a system of equations for thermoelastic problems for a medium with Nonhomogeneous Material properties is developed. An analytical method of development for isothermal problems of such a Nonhomogeneous body has already been given by Kassir under the assumption that the shear modulus of elasticity G changes with the variable z of the axial coordinate according to the relationship G(z)=G0zm. However, no analytical procedure has been established for the thermoelastic field up to data. In this study, an analytical method of developing the three-dimensional thermoelastic field is proposed by introducing the thermoelastic displacement potential function and two kinds of displacement functions. Assuming that the shear modulus of elasticity G, the thermal conductivity λ, and the coefficient of linear thermal expansion α vary with the variable ζ connected to the dimensionless axial coordinate according to the relationship G(ζ)=G0ζm, λ(ζ)=λ0ζι, α(ζ)=α0ζk, the three-dimensional temperature solution in the steady state for a thick plate is obtained and the associated thermal stress components are evaluated theoretically. Numerical calculations are carried out for several cases, taking into account the variation of Nonhomogeneous Material properties and the numerical results are graphically demonstrated.

  • Axisymmetrical Elastic Problem for a Nonhomogeneous Thick Plate Containing a Penny‐Shaped Crack
    ZAMM, 2000
    Co-Authors: S.-p. Jeon, Yoshinobu Tanigawa
    Abstract:

    This paper deals with a theoretical analysis of an axisymmetrical elastic singular stress problem for a Nonhomogeneous thick plate with a penny-shaped crack. It is assumed that the Nonhomogeneous Material property of the shear modulus of elasticity G varies with the variable of the axial coordinate z according to the power product form, i.e., G(z) = G 0 z α . As an analytical model, we consider a Nonhomogeneous thick plate with a penny-shaped crack subject to a uniformly distributed loading such as internal pressure on the crack surfaces. Then, the axisymmetrical elastic problem for such a Nonhomogeneous Material with a singular stress field can be theoretically developed making use of a fundamental equation system, which has already been proposed in our previous paper. And numerical calculations are carried out for several cases to evaluate the influences of the Nonhomogeneous parameter m of the shear modulus of elasticity G and the position of a crack in a thick plate on the elastic behavior. Numerical results for the elastic and the singular stress fields are shown graphically.

  • DERIVATION OF SYSTEMS OF FUNDAMENTAL EQUATIONS FOR A THREE-DIMENSIONAL THERMOELASTIC FIELD WITH Nonhomogeneous Material PROPERTIES AND ITS APPLICATION TO A SEMI-INFINITE BODY
    Journal of Thermal Stresses, 1999
    Co-Authors: Yoshinobu Tanigawa, Hiroyuki Morishita, Shigeo Ogaki
    Abstract:

    A method of analytical development of three-dimensional thermoelastic problems for a medium with Nonhomogeneous Material properties is developed in this article. Assuming that the shear modulus elasticity G, the thermal conductivity lambda, and the coefficient of linear thermal expansion alpha vary with the power product form of axial coordinate variable z and introducing two kinds of displacement functions and the thermoelastic displacement function, the system of fundamental differential equations for such a three-dimensional field is established. As an illustrative example, we consider the thermoelastic problem of a semi-infinite body. The three-dimensional temperature solution in a steady state is obtained and the associated components of thermal displacement and stress are evaluated theoretically. Numerical calculations are carried out for several cases taking into account the variety of the Nonhomogeneous Material properties of G, lambda, and alpha, and these results are shown graphically.

  • axisymmetrical rigid punch problem of a semi infinite body with Nonhomogeneous Material property
    Transactions of the Japan Society of Mechanical Engineers. A, 1998
    Co-Authors: Sang-pyo Jeon, Yoshinobu Tanigawa
    Abstract:

    In this study, a theoretical treatment of an elastic behavior for a Nonhomogeneous medium is developed. As one Nonhomogeneous medium, a semi-infinite body subjected to the action of a rigid punch on its surface is considered. It is assumed for the Nonhomogeneous Material property of the semi-infinite body that the shear modulus of elasticity G varies with the variable of the axial coordinate z by an arbitrary power product form. Making use of a fundamental equation system for such a Nonhomogeneous medium, an axisymmetric problem for such a singular stress field is developed theoretically. Numerical calculations are carried out for several cases taking into account the variations of the Nonhomogeneous parameter, and the numerical results for displacements, stresses and the stress intensity factor at the edge of the rigid punch are shown graphically. Thereafter, the influences of the Nonhomogeneous Material property on the elastic behaviors such as displacements, stresses and the stress intensity factor are examined.

  • Multipurpose Optimization Problem of Material Composition for Thermal Stress Relaxation Type of a Functionally Graded Circular Plate
    JSME International Journal Series A, 1998
    Co-Authors: Ryusuke Kawamura, Yoshinobu Tanigawa
    Abstract:

    In this paper, one-dimensional transient heat conduction and thermal bending problems under an axisymmetric condition are developed theoretically for a functionally graded circular plate due to a uniform heat supply from its surfaces. We construct the approach for the multipurpose optimization of the Nonhomogeneous Material composition in a functionally graded circular plate considering the relaxation of the thermal stress distribution and the improvement of the heat resistance. We deal with this multipurpose optimization using the weighting method. Using these analytical solutions for the temperature field and the associated thermoelastic one, and the approach for the multipurpose optimization of the Nonhomogeneous Material composition, numerical calculations of the optimal Material composition are carried out for a titanium alloy(Ti-6 Al-4 V)/zirconium oxide(ZrO2) functionally graded circular plate subjected to a uniform heat supply from one side of its surface. The trade-off relationship between the maximum absolute stress ratio and the maximum heat flux is elucidated. It is shown that this approach is useful for the multipurpose optimal design of Nonhomogeneous Material composition considering both the securement of strength against thermal stress and the improvement of heat resistance against thermal load.

T.C.S. Hsia - One of the best experts on this subject based on the ideXlab platform.

  • Nonhomogeneous Material milling using a robot manipulator with force controlled velocity
    Proceedings of 1995 IEEE International Conference on Robotics and Automation, 1995
    Co-Authors: Joel Zuhars, T.C.S. Hsia
    Abstract:

    This paper deals with problems that arise when robot manipulators are used in milling workpieces with Nonhomogeneous Material. Damages to the cutting tool and workpiece would occur if the cutting speed is set incorrectly with respect to the characteristics of the tool and the hardness of the workpiece Material. This concern is heightened when milling Materials which are nonhomogenous where the tool drag can vary unpredictably. It is proposed in this paper that we solve the problem by employing a force controlled velocity (FCV) strategy to automatically adjust the cutting speed in response to the force exerted at the tool tip along the cutting path. The idea of FCV is accomplished by using a nonlinear function of both force and elapsed time in place of elapsed time when evaluating the robot trajectory equation. The effectiveness of this approach is confirmed by simulation and experimentation.

  • ICRA - Nonhomogeneous Material milling using a robot manipulator with force controlled velocity
    Proceedings of 1995 IEEE International Conference on Robotics and Automation, 1
    Co-Authors: Joel Zuhars, T.C.S. Hsia
    Abstract:

    This paper deals with problems that arise when robot manipulators are used in milling workpieces with Nonhomogeneous Material. Damages to the cutting tool and workpiece would occur if the cutting speed is set incorrectly with respect to the characteristics of the tool and the hardness of the workpiece Material. This concern is heightened when milling Materials which are nonhomogenous where the tool drag can vary unpredictably. It is proposed in this paper that we solve the problem by employing a force controlled velocity (FCV) strategy to automatically adjust the cutting speed in response to the force exerted at the tool tip along the cutting path. The idea of FCV is accomplished by using a nonlinear function of both force and elapsed time in place of elapsed time when evaluating the robot trajectory equation. The effectiveness of this approach is confirmed by simulation and experimentation.

Helder C. Rodrigues - One of the best experts on this subject based on the ideXlab platform.

  • A three-dimensional hierarchical model for topology optimization of structures
    III European Conference on Computational Mechanics, 1
    Co-Authors: Pedro Coelho, Paulo R. Fernandes, João Cardoso, José M. Guedes, Helder C. Rodrigues
    Abstract:

    The topology optimization of structures consists of the identification of solid and void regions within a design domain, for a given criterion and a prescribed amount of Material. Using a Material approach, the optimal topology is achieved by the distribution in space of a Nonhomogeneous Material of variable density. Regions with high density identify structure while regions with low value are interpreted as holes.

Hideki Sekine - One of the best experts on this subject based on the ideXlab platform.

  • INVERSE PROBLEMS OF Material DISTRIBUTIONS FOR PRESCRIBED APPARENT FRACTURE TOUGHNESS IN FGM COATINGS AROUND A CIRCULAR HOLE IN INFINITE ELASTIC MEDIA
    Composites Science and Technology, 2002
    Co-Authors: A. M. Afsar, Hideki Sekine
    Abstract:

    Abstract This study is concerned with the inverse problem of calculating Material distributions intending to realize prescribed apparent fracture toughness in functionally graded Material (FGM) coatings around a circular hole in infinite elastic media. The incompatible eigenstrain induced in the FGM coatings after cooling from the sintering temperature, due to mismatch in the coefficients of thermal expansion, is taken into consideration. An approximation method of determining stress intensity factors is introduced for a crack in the FGM coatings in which the FGM coatings are homogenized simulating the Nonhomogeneous Material properties by a distribution of equivalent eigenstrain. A radial edge crack emanating from the circular hole in the homogenized coatings is considered for the case of a uniform pressure applied to the surfaces of the hole and the crack. The stress intensity factors determined for the crack in the homogenized coatings represent the approximate values of the stress intensity factors for the same crack in the FGM coatings, and are used in the inverse problem of calculating Material distributions in the FGM coatings intending to realize prescribed apparent fracture toughness in the coatings. Numerical results are obtained for a TiC/Al 2 O 3 FGM coating, which reveal that the apparent fracture toughness in FGM coatings around a circular hole in infinite elastic media can be controlled within possible limits by choosing an appropriate Material distribution profile in the coatings.

  • OPTIMIZING Material DISTRIBUTION FOR PRESCRIBED APPARENT FRACTURE TOUGHNESS IN FGM COATINGS
    2001
    Co-Authors: A. M. Afsar, Hideki Sekine
    Abstract:

    This paper is concerned with the inverse problem of optimizing Material distribution with a view to realizing prescribed apparent fracture toughness in Functionally Graded Material (FGM) coatings. The incompatible eigenstrain induced in the FGM coatings after cooling from the sintering temperature due to mismatch in the coefficients of thermal expansion is taken into consideration. Simulating the Nonhomogeneous Material properties of the FGM coatings by an equivalent eigenstrain, we present an approximation method of calculating stress intensity factor (SIF) for an edge crack in the FGM coatings. The approximation method of the SIF is used in the inverse problem of optimizing Material distribution intending to realize prescribed apparent fracture toughness in the FGM coatings. Numerical results obtained for a TiC/Al2O3 FGM coating-Al2O3 substrate reveal that the apparent fracture toughness significantly depends on the Material distribution, and can be controlled within possible limits by choosing an optimum Material distribution profile Keyword: Composite Material, Inverse problem, Functionally graded Material, Fracture toughness

  • Optimum Material distributions for prescribed apparent fracture toughness in thick-walled FGM circular pipes
    International Journal of Pressure Vessels and Piping, 2001
    Co-Authors: A. M. Afsar, Hideki Sekine
    Abstract:

    Abstract This study treats the inverse problem of evaluating optimum Material distributions intending to realize prescribed apparent fracture toughness in thick-walled functionally graded Material (FGM) circular pipes. The incompatible eigenstrain induced in the pipes after cooling from the sintering temperature due to the Nonhomogeneous coefficient of thermal expansion is taken into consideration. An approximation method of finding stress intensity factors for a crack in the FGM pipes is introduced in which the Nonhomogeneous Material properties are simulated by a distribution of equivalent eigenstrain. A radial edge crack emanating from the inner surface of the homogenized pipes is considered for the case of a uniform internal pressure applied to the surfaces of the pipes and the crack. The stress intensity factors determined for the crack in the homogenized pipes represent the approximate values of the stress intensity factors for the same crack in the FGM pipes, and are used in the inverse problem of evaluating optimum Material distributions intending to realize prescribed apparent fracture toughness in the FGM pipes. Numerical results obtained for a thick-walled TiC/Al 2 O 3 FGM pipe reveal that the apparent fracture toughness significantly depends on the Material distributions, and can be controlled within possible limits by choosing an optimum Material distribution profile.

Joel Zuhars - One of the best experts on this subject based on the ideXlab platform.

  • Nonhomogeneous Material milling using a robot manipulator with force controlled velocity
    Proceedings of 1995 IEEE International Conference on Robotics and Automation, 1995
    Co-Authors: Joel Zuhars, T.C.S. Hsia
    Abstract:

    This paper deals with problems that arise when robot manipulators are used in milling workpieces with Nonhomogeneous Material. Damages to the cutting tool and workpiece would occur if the cutting speed is set incorrectly with respect to the characteristics of the tool and the hardness of the workpiece Material. This concern is heightened when milling Materials which are nonhomogenous where the tool drag can vary unpredictably. It is proposed in this paper that we solve the problem by employing a force controlled velocity (FCV) strategy to automatically adjust the cutting speed in response to the force exerted at the tool tip along the cutting path. The idea of FCV is accomplished by using a nonlinear function of both force and elapsed time in place of elapsed time when evaluating the robot trajectory equation. The effectiveness of this approach is confirmed by simulation and experimentation.

  • ICRA - Nonhomogeneous Material milling using a robot manipulator with force controlled velocity
    Proceedings of 1995 IEEE International Conference on Robotics and Automation, 1
    Co-Authors: Joel Zuhars, T.C.S. Hsia
    Abstract:

    This paper deals with problems that arise when robot manipulators are used in milling workpieces with Nonhomogeneous Material. Damages to the cutting tool and workpiece would occur if the cutting speed is set incorrectly with respect to the characteristics of the tool and the hardness of the workpiece Material. This concern is heightened when milling Materials which are nonhomogenous where the tool drag can vary unpredictably. It is proposed in this paper that we solve the problem by employing a force controlled velocity (FCV) strategy to automatically adjust the cutting speed in response to the force exerted at the tool tip along the cutting path. The idea of FCV is accomplished by using a nonlinear function of both force and elapsed time in place of elapsed time when evaluating the robot trajectory equation. The effectiveness of this approach is confirmed by simulation and experimentation.