1,721,157 research outputs found
Sensitivity analysis for boundary element error estimation and mesh refinement
No full textThe subject of this paper is the sensitivity analysis of approximate boundary element solutions with respect to the positions of the collocation points. The direct differentiation approach is considered here and the analysis is performed analytically. Since only the collocation points are perturbed, the shape of the body and the corresponding discretization remain unaltered. This aspect makes the present work quite different in spirit with respect to earlier analyses on shape sensitivities. Sensitivities of approximate BEM solutions with respect to the positions of collocation points are shown to be related to the residual of hypersingular integral equations. Numerical results confirm that the present approach can be seen as the analytical counterpart of an adaptive scheme for mesh refinement presented by the same author in some recent papers. Some other advantages of the present approach over the former one are also outlined
HYPERSINGULAR BOUNDARY INTEGRAL-EQUATIONS HAVE AN ADDITIONAL FREE TERM
No full textIn this paper it is shown that hypersingular boundary integral equations may have an additional free term which has been erroneously omitted in former analyses
HYPERSINGULAR FORMULATION FOR BOUNDARY STRESS EVALUATION
No full textInstead of using shape function derivatives and Hooke's law, the full stress tensor is evaluated at boundary points by direct application of boundary integral identities for the displacement derivatives. It is first shown that integral equations with singular or hypersingular kernels do not give rise to unbounded terms, even when the source point is on the boundary. A general method for performing the integration is also described. Numerical results are quite interesting, since the stress components evaluated through the hypersingular integral equation method show very good accuracy even on coarse meshes
THE EVALUATION OF CAUCHY PRINCIPAL VALUE INTEGRALS IN THE BOUNDARY ELEMENT METHOD - A REVIEW
No full textIn this paper several methods of dealing with Cauchy Principal Value integrals in advanced boundary element methods are discussed and compared. An attempt is made to present a comprehensive description of these methods in a unified, systematic manner. It is shown that the methods can be grouped into two basic approaches, the (more classical) indirect approach, such as the rigid-body motion technique in elastostatics, and the (more recent) direct approach, that allows any Cauchy Principal Value integral to be evaluated by standard quadrature formulae
DYNAMIC INSTABILITY IN FLUID-COUPLED COAXIAL CYLINDRICAL-SHELLS UNDER HARMONIC EXCITATION
No full textThe science of vehicle dynamics: handling, braking, and ride of road and race cars
No full textVehicle dynamics is often perceived as a quite intuitive subject. As a matter of fact, lots of people are able to drive a car. Nevertheless, without a rigorous mathematical formulation it is very difficult to truly understand the physical phenomena involved in the motion of a road vehicle. In this book, mathematical models of vehicles are developed, always paying attention to state the relevant assumptions and to provide explanations for each step. This approach allows for a deep, yet simple, analysis of the dynamics of vehicles, without having to resort to foggy concepts. The reader will soon achieve a clear understanding of the subject, which will be of great help both in dealing with the challenges of designing and testing new vehicles and in tackling new research topics. The book covers handling and performance of both road and race cars. A new approach, called MAP (Map of Achievable Performance), is presented and thoroughly discussed. It provides a global and intuitive picture of the handling features of a vehicle. Moreover, the book also deals with several relevant topics in vehicle dynamics that have never been discussed before. Massimo Guiggiani is professor of Applied Mechanics at the Università di Pisa, where he also teaches Vehicle Dynamics in the MS degree program in Vehicle Engineering
A SELF-ADAPTIVE COORDINATE TRANSFORMATION FOR EFFICIENT NUMERICAL EVALUATION OF GENERAL BOUNDARY ELEMENT INTEGRALS
No full text
COMPUTING PRINCIPAL-VALUE INTEGRALS IN 3-D BEM FOR TIME-HARMONIC ELASTODYNAMICS - A DIRECT APPROACH
No full textCurrent methods to deal with Cauchy principal-value (CPV) integrals in advanced boundary-element implementations have been almost entirely based on indirect approaches (such as the rigid-body motion in elastostatics). The present paper illustrates an alternative direct approach for the rigorous treatment and numerical evaluation of general CPV integrals in three-dimensional problems. The method has general validity. It can be applied in any field of applied mechanics and with curved boundary elements of any order and type. As expected, the mesh pattern around the pole does not affect the numerical results
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