Numerical experiments on the determination of stress concentration factors in orthotropic perforated plates subjected to in - plane loading

Bambill, D.V.,Rossit, C.A.,Susca, A. Techno-Press 2009 Structural Engineering and Mechanics, An Int'l Jou Vol.32 No.4

As it is known, laminated composite materials are increasingly used in many technological applications, and in some instance, cutouts must be made into laminated panels for practical reasons, changing the stress distribution. The present study deals with the determination of the stress concentration factor that holes of square shape cause in an orthotropic plate subjected to distributed in - plane loading. Square holes of rounded corners in a rectangular plate are considered, and the effect of different combinations of axial and tangential forces applied to its middle plane at the external edges, is studied. The mutually perpendicular axes, which define the principal axes of orthotropy, are assumed in many different directions referred to the sides of the plate. Numerical experiments by means of a finite element code is performed, evaluating the influence of the fiber orientation with respect to the edges of the plate and the characteristics of the orthotropic materials since such structures do not exhibit easily predictable behavior.

Vibration analysis of rotating Timoshenko beams by means of the differential quadrature method

Bambill, D.V.,Felix, D.H.,Rossi, R.E. Techno-Press 2010 Structural Engineering and Mechanics, An Int'l Jou Vol.34 No.2

Vibration analysis of rotating beams is a topic of constant interest in mechanical engineering. The differential quadrature method (DQM) is used to obtain the natural frequencies of free transverse vibration of rotating beams. As it is known the DQM offers an accurate and useful method for solution of differential equations. And it is an effective technique for solving this kind of problems as it is shown comparing the obtained results with those available in the open literature and with those obtained by an independent solution using the finite element method. The beam model is based on the Timoshenko beam theory.

Vibration analysis of rotating Timoshenko beams by means of the differential quadrature method

D.V. Bambill,D.H. Felix,R.E. Rossi 국제구조공학회 2010 Structural Engineering and Mechanics, An Int'l Jou Vol.34 No.2

Vibration analysis of rotating beams is a topic of constant interest in mechanical engineering. The differential quadrature method (DQM) is used to obtain the natural frequencies of free transverse vibration of rotating beams. As it is known the DQM offers an accurate and useful method for solution of differential equations. And it is an effective technique for solving this kind of problems as it is shown comparing the obtained results with those available in the open literature and with those obtained by an independent solution using the finite element method. The beam model is based on the Timoshenko beam theory.

Numerical experiments on the determination of stress concentration factors in orthotropic perforated plates subjected to in - plane loading

D.V. Bambill,C.A. Rossit,A. Susca 국제구조공학회 2009 Structural Engineering and Mechanics, An Int'l Jou Vol.32 No.4

As it is known, laminated composite materials are increasingly used in many technological applications, and in some instance, cutouts must be made into laminated panels for practical reasons, changing the stress distribution. The present study deals with the determination of the stress concentration factor that holes of square shape cause in an orthotropic plate subjected to distributed in . plane loading. Square holes of rounded corners in a rectangular plate are considered, and the effect of different combinations of axial and tangential forces applied to its middle plane at the external edges, is studied. The mutually perpendicular axes, which define the principal axes of orthotropy, are assumed in many different directions referred to the sides of the plate. Numerical experiments by means of a finite element code is performed, evaluating the influence of the fiber orientation with respect to the edges of the plate and the characteristics of the orthotropic materials since such structures do not exhibit easily predictable behavior.

Free vibration of a rectangular plate with an attached three-degree-of-freedom spring-mass system

Febbo, M.,Bambill, D.V.,Rossi, R.E. Techno-Press 2011 Structural Engineering and Mechanics, An Int'l Jou Vol.40 No.5

The present paper studies the variation of the natural frequencies and mode shapes of rectangular plates carrying a three degree-of-freedom spring-mass system (subsystem), when the subsystem changes (stiffness, mass, moment of inertia, location). An analytical approach based on Lagrange multipliers as well as a finite element formulation are employed and compared. Numerically reliable results are presented for the first time, illustrating the convenience of using the present analytical method which requires only the solution of a linear eigenvalue problem. Results obtained through the variation of the mass, stiffness and moment of inertia of the 3-DOF system can be understood under the effective mass concept or Rayleigh's statement. The analysis of frequency values of the whole system, when the 3-DOF system approaches or moves away from the center, shows that the variations depend on each particular mode of vibration. When the 3-DOF system is placed in the center of the plate, "new" modes are found to be a combination of the subsystem's modes (two rotations, traslation) and the bare plate's modes that possess the same symmetry. This situation no longer exists as the 3-DOF system moves away from the center of the plate, since different bare plate's modes enable distinct motions of the 3-DOF system contributing differently to the "new' modes as its location is modified. Also the natural frequencies of the compound system are nearly uncoupled have been calculated by means of a first order eigenvalue perturbation analysis.

A note on buckling and vibration of clamped orthotropic plates under in-plane loads

Felix, D.H.,Bambill, D.V.,Rossit, C.A. Techno-Press 2011 Structural Engineering and Mechanics, An Int'l Jou Vol.39 No.1

The present work deals with obtaining the critical buckling load and the natural frequencies of clamped, orthotropic, rectangular thin plates subjected to different linear distributed in-plane forces. An analytical solution is proposed. Using the Ritz method, the dependence between in-plane forces and natural frequencies are estimated for various plate sizes, and some results are compared with finite element solutions and where possible, comparison is made with previously published results. Beam functions are used as admissible functions in the Ritz method.

Timoshenko theory effect on the vibration of axially functionally graded cantilever beams carrying concentrated masses

Rossit, Carlos A.,Bambill, Diana V.,Gilardi, Gonzalo J. Techno-Press 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.66 No.6

In this paper is studied the effect of considering the theory of Timoshenko in the vibration of AFG beams that support ground masses. As it is known, Timoshenko theory takes into account the shear deformation and the rotational inertia, provides more accurate results in the general study of beams and is mandatory in the case of high frequencies or non-slender beams. The Rayleigh-Ritz Method is employed to obtain approximated solutions of the problem. The accuracy of the procedure is verified through results available in the literature that can be represented by the model under study. The incidence of the Timoshenko theory is analyzed for different cases of beam slenderness, variation of its cross section and compositions of its constituent material, as well as different amounts and positions of the attached masses.

Free vibration of a rectangular plate with an attached three-degree-of-freedom spring-mass system

M. Febbo,D.V. Bambill,R.E. Rossi 국제구조공학회 2011 Structural Engineering and Mechanics, An Int'l Jou Vol.40 No.5

The present paper studies the variation of the natural frequencies and mode shapes of rectangular plates carrying a three degree-of-freedom spring-mass system (subsystem), when the subsystem changes (stiffness, mass, moment of inertia, location). An analytical approach based on Lagrange multipliers as well as a finite element formulation are employed and compared. Numerically reliable results are presented for the first time, illustrating the convenience of using the present analytical method which requires only the solution of a linear eigenvalue problem. Results obtained through the variation of the mass, stiffness and moment of inertia of the 3-DOF system can be understood under the effective mass concept or Rayleigh’s statement. The analysis of frequency values of the whole system, when the 3-DOF system approaches or moves away from the center, shows that the variations depend on each particular mode of vibration. When the 3-DOF system is placed in the center of the plate, “new” modes are found to be a combination of the subsystem’s modes (two rotations, traslation) and the bare plate’s modes that possess the same symmetry. This situation no longer exists as the 3-DOF system moves away from the center of the plate, since different bare plate’s modes enable distinct motions of the 3-DOF system contributing differently to the “new’ modes as its location is modified. Also the natural frequencies of the compound system are nearly uncoupled have been calculated by means of a first order eigenvalue perturbation analysis.

Timoshenko theory effect on the vibration of axially functionally graded cantilever beams carrying concentrated masses

Carlos A. Rossit,Diana V. Bambill,Gonzalo J. Gilardi 국제구조공학회 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.66 No.6

In this paper is studied the effect of considering the theory of Timoshenko in the vibration of AFG beams that support ground masses. As it is known, Timoshenko theory takes into account the shear deformation and the rotational inertia, provides more accurate results in the general study of beams and is mandatory in the case of high frequencies or non-slender beams. The Rayleigh-Ritz Method is employed to obtain approximated solutions of the problem. The accuracy of the procedure is verified through results available in the literature that can be represented by the model under study. The incidence of the Timoshenko theory is analyzed for different cases of beam slenderness, variation of its cross section and compositions of its constituent material, as well as different amounts and positions of the attached masses.

A note on buckling and vibration of clamped orthotropic plates under in-plane loads

D.H. Felix,D.V. Bambill,C.A. Rossit 국제구조공학회 2011 Structural Engineering and Mechanics, An Int'l Jou Vol.39 No.1

The present work deals with obtaining the critical buckling load and the natural frequencies of clamped, orthotropic, rectangular thin plates subjected to different linear distributed in-plane forces. An analytical solution is proposed. Using the Ritz method, the dependence between in-plane forces and natural frequencies are estimated for various plate sizes, and some results are compared with finite element solutions and where possible, comparison is made with previously published results. Beam functions are used as admissible functions in the Ritz method.