Yves Christian MBONO SAMBA

An Attempt to Study Foundation Anchoring Conditions in Sedimentary Estuaries Using Integrated Methods

Blaise Pascal Gounou Pokam, Janvier Domra Kana, Jorelle Larissa Méli’i, Marthe Mbond Ariane Gweth, Serges Hugues Pokam Kegni, Michel Constant Njock and 4 more

Applied Sciences

The search for and knowledge of the best conditions for anchoring the foundations of certain structures such as bridges, tunnels and quays in sedimentary estuaries is a challenge, for both scientists in general and engineers in particular. Indeed, wharves are structures that receive a lot of stresses and therefore require anchoring to avoid tilting and to guarantee their stability during service. This work, based on the analysis of data from seismic refraction methods, mechanical soundings and laboratory tests, characterises the terrain of the Wouri estuary in Central Africa. The objective is to determine and present the subsurface layers encountered as well as their characteristics, in order to define the best conditions for anchoring the foundations to ensure the stability of the quays to be built there. The seismic refraction campaign shows that the study area is relatively heterogeneous over the first 25 m, with velocities measured in the range 1520–1750 m/s; modulated in two distinct ranges, between 1520–1580 m/s characteristic of mud and loose sediments (alternating layers of clay, sand, loose silt) and the range 1580–1750 m/s corresponding to the signature of sandy-silty or compact clays. The mechanical tests show sedimentary soils, with alternating layers of sandy clay and clayey sand over the 42 m drilled, loose over the first 30 m in the bank area and over the first 15 m in the canal or dredge area, with a limit pressure of less than 1 MPa. Similarly, the soil samples taken and tested in the laboratory show that the soils are clayey over the first 30 metres, plastic and liquid with respect to their water content, respectively, below and above the liquidity limits, confirming their loose character. The results of seismic refraction, mechanical soundings and laboratory tests show that, in estuarine areas characterised by alternating sandy clay and clayey sand, there are not always hard formations in the first 25 metres of depth but, from a depth of 30 m, the soils become moderately compact and begin to form an anchoring layer sufficient to guarantee the stability of the quays against earth pressure forces.

• #geotechnical engineering and underground structures
• #geotechnical and construction materials studies
• #geotechnical engineering and soil mechanics
• #anchoring

Effects of an external constant pressure gradient on a steady incompressible laminar flow through a semi-porous annular pipe

Guy Leopold Mbogba, Elisabeth Ngo Nyobe, Maurice Lamara, Yves Christian Mbono Samba, Elkana Pemha

Zeitschrift für Naturforschung A

Abstract In this paper, we examine a steady laminar flow for an incompressible fluid located in a semi porous annular pipe and subjected to a favorable constant pressure gradient applied between the two borders of the pipe. The inner wall is impermeable and the fluid is sucked or injected at the outer wall at constant and uniform velocity, orthogonally to the wall. The problem under study depends on three parameters: the pipe gap ratio, the dimensionless external pressure gradient, and the Reynolds number defined from the sum of the suction or injection velocity and the maximum Hagen–Poiseuille velocity. The conservation of mass induces the zero-divergence velocity field which allows replacing the steady-flow Navier–Stokes equations with a single equation satisfied by the stream function and called the vorticity equation. Assuming the similarity-solution hypothesis, the problem under consideration is reduced to a fourth-order nonlinear ordinary differential equation with two boundary conditions at each wall. The numerical shooting technique including the Runge–Kutta algorithm and the Newton–Raphson optimization method is applied to obtain the solution for the steady flow. For various values of the dimensionless external pressure gradient, the profiles of the velocity components are found and investigations on the wall shear stress for both walls are performed. The results obtained are discussed and physical understandings for the problem studied are derived.

• #rocket and propulsion systems research
• #nanofluid flow and heat transfer
• #gas dynamics and kinetic theory
• #laminar flow

Assessment of the Significance of Nonlinear Terms in the Simulation of Flexible Multibody Systems

Yves Christian Mbono Samba, M. Pascal

International Journal for Multiscale Computational Engineering

The work is concerned with the dynamics of multibody systems with flexible parts undergoing large rigid body motions and small elastic deformations. An attempt to evaluate the influence of nonlinear terms with respect to elastic parameters occurring in the global motion of the system is performed. These nonlinear terms come from centrifugal and Coriolis forces related to the rigid rotation of the bodies. Several studies have been made in the past about this problem, and some approximations or simplifications are sometimes suggested. In order to quantify the relative size of these nonlinear terms, a non dimensional analysis is performed, with some assumptions about the order of magnitude of the different parameters occurring in the dynamical system obtained by Kane’s method. A flexible slider crank mechanism is used as a test example.

• #dynamics and control of mechanical systems
• #vehicle dynamics and control systems
• #robotic mechanisms and dynamics
• #nonlinear system

DYNAMIC ANALYSIS AND NUMERICAL SIMULATION OF FLEXIBLE MULTIBODY SYSTEMS *

Yves Christian Mbono Samba, Madeleine Pascal

Mechanics of Structures and Machines

Numerous studies about the modelization of multibody systems with flexible parts undergoing large rigid body motions and small elastic deformations have recently been performed [[1] Koppens, W. P. 1989. The Dynamics of Systems of Deformable Bodies, thesis Eindhoven, , Germany: Technische Universiteit Eindhoven. [Google Scholar] [2] Pascal, M. 1988. Dynamical Analysis of a System of Hinged-Connected Flexible Bodies. Celestial Mech., 41: 253–274. [Crossref], [Web of Science ®] , [Google Scholar] [3] Pascal, M. 1995. Nonlinear Effects in Transient Dynamic Analysis of Flexible Multibody System. Design Eng. Tech. Conf., DE 84–1 (3, p. A) [Google Scholar] [4] Pascal, M. 1990. Dynamical Analysis of a Flexible Manipulator Arm. Acta Astronautica, 21(3): 161–169. [Crossref], [Web of Science ®] , [Google Scholar] [5] Pascal, M. 1991. Vibrations Analysis of Flexible Multibody Systems. Dyn. Stabil. Sys., 6(3) [Google Scholar] [6] Pascal, M and Sylla, M. 1993. Dynamic Model of a Large Space Structure by a Continuous Approach. Recherche Aérospas, 2 [Google Scholar] [7] Pascal, M. 1987. La Stabilité d'un Satellite Muni de Panneaux Solaires. Acta Astronautica, 5: 817–844. [Crossref] , [Google Scholar] [8] Meirovitch, L. 1967. Analytical Method in Vibrations 440–45. New York: MacMillan. [Google Scholar] [9] Hughes, P. C. 1974. Dynamics of Flexible Space Vehicles with Active Attitude Control. Celestial Mech., 9: 21–39. [Crossref] , [Google Scholar] [10] Likins, P. W., Barbera, F. J. and Baddeley, V. 1973. Mathematical Modeling of Spinning Elastic Bodies for Modal Analysis. AIAA J., 11: 1251–1258. [Crossref] , [Google Scholar] [11] Vigneron, F. R. 1975. Mathematical Modeling of Spinning Elastic Bodies for Modal Analysis [Comment]. AIAA J., 13: 126–127. [Crossref] , [Google Scholar] [12] Kane, T. R., Ryan, R. R. and Banerjee, A. K. March–April 1987. Dynamics of a Cantilever Beam Attached to a Moving Base. J. Guidance, 10(2): 139–151. [Crossref], [Web of Science ®] , [Google Scholar] [13] Simo, J. C. and Vu-Quoc, L. December 1986. On the Dynamics of Flexible Beams Undergoing Large Overall Motions—The Plane Case: Part I. J. Appl. Mech., 53: 849–854. [Crossref], [Web of Science ®] , [Google Scholar] [14] Simo, J. C. and Vu-Quoc, L. 1987. The Role of Nonlinear Theories in Transient Dynamic Analysis of Flexible Structures. J. Sound Vibration, 119(3): 487–508. [Crossref], [Web of Science ®] , [Google Scholar] [15] Wallrap, J and Santos, Ryu. 1990. “Superposition Method for Stress Stiffening in Flexible Multibody Dynamics”. In Proceedings of International Conference on Dynamics of Flexible Structures in Space Edited by: Kirk, C. L. and Junkins, J. L. 233–247. Cranfield, , UK: CMP and Springer Verlag. [Google Scholar] [16] Banerjee, K and Lemak, M. E. September 1991. Multi-flexible Body Dynamics Capturing Motion- Induced Stiffness. J. Appl. Mech., 58: 766–775. [Crossref], [Web of Science ®] , [Google Scholar] [17] Banerjee, K and Dickens, J. M. 1989. Dynamics of an Arbitrary Flexible Body Ungoing Large Rotation and Translation with Small Vibration. Presented at the 30th AIAA/ASME/ASCE/AHS/ACS Structures. Structural Dynamics and Material Conference. April3–51989, Mobile, Alabama. [Crossref] , [Google Scholar] [18] Wielenga, T. J. 1984. Simplifications in the Simulation of Mechanism Containing Flexible Members, thesis Ann Arbor: University of Michigan. [Google Scholar] [19] Hsieh, S.-R. and Shaw, S. W. 1993. The Dynamic Stability and Nonlinear Resonance of a Flexible Connecting Rod: Continuous Parameter Model. Presented at the 14th ASME Conference on Mechanics Vibration and Noise. 1993, Albuquerque, New Mexico. [Crossref] , [Google Scholar] [20] Sharf, I. Geometric Stiffening in Multibody Formulations, [Google Scholar] [21] Padilla, E and Von Flotow, A. H. 1990. Nonlinear Strain-Displacement Relations and Flexible Multibody Dynamics. AIAA J., [Google Scholar] [22] Padilla, E and Von Flotow, A. H. 1991. Further Approximations in Flexible Multibody Dynamics. AIAA J., [Google Scholar] [23] Ider, K and Amirouche, F. M. November–December 1989. Influence of Nonlinearities in the Dynamics of Flexible Treelike Structures. J. Guidance, 12[Crossref], [Web of Science ®] , [Google Scholar] [24] Gofron, M and Shabana, A. 1993. Effects of the Linearization of the Coriolis and Centrifugal Forces on the Feedforward Control Law of Flexible Mechanical Systems. 14th ASME Conference on Mechanics Vibration and Noise. 1993, Albuquerque, NM. [Google Scholar] [25] Bakr, M and Shabana, A. A. 1986. Geometrically Nonlinear Analysis of Multibody Systems. Computers Struct., 23(6): 739–751. [Crossref], [Web of Science ®] , [Google Scholar] [26] Wallrap, O, Rulka, W and Maurer, M. April 1991. Comparison of Two Approaches to Incorporate Geometric Stiffness Terms in Flexible Multibody Dynamics. IMAC Firenze (Italy), [Google Scholar] [27] Wallrap, O. 1991. Linearized Flexible Multibody Dynamics Including Geometric Stiffening Effects. Mech. Struct. Machines, 19(13): 385–409. [Taylor & Francis Online] , [Google Scholar] [28] Singh, R. P., Van der Voort, R. J. and Likins, P. W. 1985. Dynamics of Flexible Bodies in Tree Topology, a Computer Oriented Approach. J. Guidance, Control Dynamics, 8: 584–590. [Crossref], [Web of Science ®] , [Google Scholar] [29] Agrawal, O. P. and Shabana, A. A. 1985. Dynamic Analysis of Multibody Systems Using Component Modes. Computers Struct., 21(6): 1303–1312. [Crossref], [Web of Science ®] , [Google Scholar] [30] Mbono, Samba C. and Pascal, M. Effets Nonlineaires Dans la Dynamique des Systémes Multicorps Flexibles, 2nd congrés de mécanique. Faculté des Sciences Aïn Chok-Casablanca, 1995 [Google Scholar] [31] Mbono, Samba Y.C. 1995. Dynamique et Simulation Numérique des Systèmes Multicorps à Composants Flexibles, thesis University of Paris 6. [Google Scholar]]. Some of them [[10] Likins, P. W., Barbera, F. J. and Baddeley, V. 1973. Mathematical Modeling of Spinning Elastic Bodies for Modal Analysis. AIAA J., 11: 1251–1258. [Crossref] , [Google Scholar] [11] Vigneron, F. R. 1975. Mathematical Modeling of Spinning Elastic Bodies for Modal Analysis [Comment]. AIAA J., 13: 126–127. [Crossref] , [Google Scholar] [12] Kane, T. R., Ryan, R. R. and Banerjee, A. K. March–April 1987. Dynamics of a Cantilever Beam Attached to a Moving Base. J. Guidance, 10(2): 139–151. [Crossref], [Web of Science ®] , [Google Scholar] [13] Simo, J. C. and Vu-Quoc, L. December 1986. On the Dynamics of Flexible Beams Undergoing Large Overall Motions—The Plane Case: Part I. J. Appl. Mech., 53: 849–854. [Crossref], [Web of Science ®] , [Google Scholar] [14] Simo, J. C. and Vu-Quoc, L. 1987. The Role of Nonlinear Theories in Transient Dynamic Analysis of Flexible Structures. J. Sound Vibration, 119(3): 487–508. [Crossref], [Web of Science ®] , [Google Scholar] [15] Wallrap, J and Santos, Ryu. 1990. “Superposition Method for Stress Stiffening in Flexible Multibody Dynamics”. In Proceedings of International Conference on Dynamics of Flexible Structures in Space Edited by: Kirk, C. L. and Junkins, J. L. 233–247. Cranfield, , UK: CMP and Springer Verlag. [Google Scholar] [16] Banerjee, K and Lemak, M. E. September 1991. Multi-flexible Body Dynamics Capturing Motion- Induced Stiffness. J. Appl. Mech., 58: 766–775. [Crossref], [Web of Science ®] , [Google Scholar] [17] Banerjee, K and Dickens, J. M. 1989. Dynamics of an Arbitrary Flexible Body Ungoing Large Rotation and Translation with Small Vibration. Presented at the 30th AIAA/ASME/ASCE/AHS/ACS Structures. Structural Dynamics and Material Conference. April3–51989, Mobile, Alabama. [Crossref] , [Google Scholar]], [[20] Sharf, I. Geometric Stiffening in Multibody Formulations, [Google Scholar], [[25] Bakr, M and Shabana, A. A. 1986. Geometrically Nonlinear Analysis of Multibody Systems. Computers Struct., 23(6): 739–751. [Crossref], [Web of Science ®] , [Google Scholar] [26] Wallrap, O, Rulka, W and Maurer, M. April 1991. Comparison of Two Approaches to Incorporate Geometric Stiffness Terms in Flexible Multibody Dynamics. IMAC Firenze (Italy), [Google Scholar]], [[28] Singh, R. P., Van der Voort, R. J. and Likins, P. W. 1985. Dynamics of Flexible Bodies in Tree Topology, a Computer Oriented Approach. J. Guidance, Control Dynamics, 8: 584–590. [Crossref], [Web of Science ®] , [Google Scholar]] focused on the influence of geometric nonlinearities, and others [[18] Wielenga, T. J. 1984. Simplifications in the Simulation of Mechanism Containing Flexible Members, thesis Ann Arbor: University of Michigan. [Google Scholar] [19] Hsieh, S.-R. and Shaw, S. W. 1993. The Dynamic Stability and Nonlinear Resonance of a Flexible Connecting Rod: Continuous Parameter Model. Presented at the 14th ASME Conference on Mechanics Vibration and Noise. 1993, Albuquerque, New Mexico. [Crossref] , [Google Scholar]], [[21] Padilla, E and Von Flotow, A. H. 1990. Nonlinear Strain-Displacement Relations and Flexible Multibody Dynamics. AIAA J., [Google Scholar] [22] Padilla, E and Von Flotow, A. H. 1991. Further Approximations in Flexible Multibody Dynamics. AIAA J., [Google Scholar] [23] Ider, K and Amirouche, F. M. November–December 1989. Influence of Nonlinearities in the Dynamics of Flexible Treelike Structures. J. Guidance, 12[Crossref], [Web of Science ®] , [Google Scholar] [24] Gofron, M and Shabana, A. 1993. Effects of the Linearization of the Coriolis and Centrifugal Forces on the Feedforward Control Law of Flexible Mechanical Systems. 14th ASME Conference on Mechanics Vibration and Noise. 1993, Albuquerque, NM. [Google Scholar]], [[30] Mbono, Samba C. and Pascal, M. Effets Nonlineaires Dans la Dynamique des Systémes Multicorps Flexibles, 2nd congrés de mécanique. Faculté des Sciences Aïn Chok-Casablanca, 1995 [Google Scholar] [31] Mbono, Samba Y.C. 1995. Dynamique et Simulation Numérique des Systèmes Multicorps à Composants Flexibles, thesis University of Paris 6. [Google Scholar]] focused on the terms describing dynamic nonlinearities. In this work [[30] Mbono, Samba C. and Pascal, M. Effets Nonlineaires Dans la Dynamique des Systémes Multicorps Flexibles, 2nd congrés de mécanique. Faculté des Sciences Aïn Chok-Casablanca, 1995 [Google Scholar] [31] Mbono, Samba Y.C. 1995. Dynamique et Simulation Numérique des Systèmes Multicorps à Composants Flexibles, thesis University of Paris 6. [Google Scholar]], we look at the dynamic nonlinearities. The method usually used to model the motion of such systems consists of separating the motion of each component of the system of rigid body motion and small elastic deformations and keeps only the linear terms connected to them. In some cases of fast motion, the problem of the accuracy of this linearization occurs. Precisely, it has been noted that small deformations do not imply small rates of deformation or small accelerations of deformation [[18] Wielenga, T. J. 1984. Simplifications in the Simulation of Mechanism Containing Flexible Members, thesis Ann Arbor: University of Michigan. [Google Scholar]]. The question then raised is to know if this linearization is too premature. After establishing a method to allow the evaluation of the relative importance of nonlinearity terms, it appears that these terms must be kept in some cases. The obtained method is general and does not concern only the dynamic terms. A slider-crank mechanism was used to test the theory. Kane's method [[32] Tran, D. M. 1991. Une Présentation de la Méthode de Kane Pour la Formulation des É quations du Mouvement. Recherche Aérospatiale, 3: 1–21. [Google Scholar]] was used to establish the equations of motion, and the software AUTOLEV (Online Dynamics, Sunnyvale, CA) was used for numerical study.

• #dynamics and control of mechanical systems
• #mechanical engineering and vibrations research
• #robotic mechanisms and dynamics
• #multibody system

Prevalence ofdepigmentation oftheshins: a simple andcheapwaytoscreenforsevere endemiconchocerciasis inAfrica

B. Carme, V. Ntsoumou-Madzou, Yves Christian Mbono Samba, A. Yebakima

• #parasite biology and host interactions
• #parasitic diseases research and treatment
• #insects and parasite interactions
• #simple (philosophy)