Flexible multibody dynamics approach for tire dynamics simulation

Coordinate reduction has been widely used for efficient simulation of flexible multibody dynamics. To achieve the reduction of flexible bodies with reasonable accuracy, the appropriate number of dominant modes used for the reduction process must be selected. To handle this issue, an iterative coordinate reduction strategy is introduced. In the iteration step, more dominant modes of flexible bodies are selected than the ones in the previous step. Among the various methods, the conventional frequency cut-off rule is here considered. As a stop criterion, a novel a posteriori error estimator that can evaluate the relative eigenvalue error between full and reduced flexible bodies is proposed. Through the estimated relative eigenvalue error obtained, the number of dominant modes is automatically selected to satisfy the error tolerance up to the desired mode range. The applicability to the automation process is verified through numerical examples. It is also evaluated that efficient and accurate flexible multibody dynamics simulation is available with the reduced flexible body, generated by the proposed algorithm.

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Nonlinear Flexible Multibody Dynamics Simulation of Operating Shock Response and Head Lift-Off in Hard Disk Drives

Volume 4: 7th International Conference on Multibody Systems, Nonlinear Dynamics, and Control, Parts A, B and C ◽

10.1115/detc2009-86818 ◽

2009 ◽

Author(s):

Takehiko Eguchi ◽

Noritaka Otake ◽

Keiko Watanabe

Keyword(s):

Multibody Dynamics ◽

Hard Disk Drives ◽

Flexible Multibody Dynamics ◽

Base Plate ◽

Hard Disk ◽

Dynamics Simulation ◽

Disk Drives ◽

Shock Response ◽

Flexible Multibody ◽

Lift Off

This paper describes a method of simulating the operational shock (op-shock) response of hard disk drives (HDDs) and its application to improving the op-shock robustness of HDDs. This flexible multibody dynamics simulation model is based on component-mode synthesis of three components; a rotating part including rotating disks and the hub/shaft of the spindle motor, a stationary part including base plate, top cover, and other major stationary parts, and an actuator part representing the moving parts of the head actuator mounted on head sliders. These components are connected to each other by fluid dynamic bearings, pivot bearings, and air bearings, and their nonlinear characteristics are considered in the op-shock response simulation. Linear and nonlinear drive-level simulation models were built, and their accuracies were experimentally verified in terms of their predicted linear frequency response, nonlinear time historical response, and head lift-off boundary. Moreover, a parametric study was performed to improve the op-shock robustness of a 2.5-inch HDD for the head lift-off boundaries of 3920 m/s2 (400 G) and 4900 m/s2 (500 G). The study indicated that the HDD model sensitivities to changes in the stiffness of the base plate and in the thickness of the disk were substantial but they saturated as the parameters became larger. The results indicated that the head lift-off boundary of 3920 m/s2 can be reached by making small modifications to the parts design, but the 4900 m/s2 boundary can’t be reached without the whole drive system being redesigned.

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Integrating 3D Stress Analysis With Flexible Multibody Dynamics Simulation

Volume 6: 13th International Conference on Multibody Systems, Nonlinear Dynamics, and Control ◽

10.1115/detc2017-67537 ◽

2017 ◽

Author(s):

Olivier A. Bauchau ◽

Shilei Han

Keyword(s):

Multibody Dynamics ◽

Axial Stress ◽

Three Dimensional ◽

Flexible Multibody Dynamics ◽

Beam Theory ◽

Torsional Stiffness ◽

Dynamics Simulation ◽

Numerical Examples ◽

Axial Forces ◽

Flexible Multibody

This paper presents an approach toward the integration of 3D stress computation with the tools used for the simulation of flexible multibody dynamics. Due to the low accuracy of the floating frame of reference approach, the the multibody dynamics community has turned its attention to comprehensive analysis tools based on beam theory. These tools evaluate sectional stress resultants, not 3D stress fields. The proposed approach decomposes the 3D problem into two simpler problems: a linear 2D analysis of the cross-section of the beam and a nonlinear, 1D of the beam. This procedure is described in details. For static problems, the proposed approach provides exact solutions of three-dimensional elasticity for uniform beams of arbitrary geometric configuration and made of anisotropic composite materials. While this strategy has been applied to dynamic problems, little attention has been devoted to inertial effects. This paper assesses the range of validity of the proposed beam theory when applied to dynamics problems. When beams are subjected to large axial forces, the induced axial stress components become inclined, generating a net torque that opposes further rotation of the section and leading to an increased effective torsional stiffness. This behavior, referred to as the Wagner or trapeze effect, cannot be captured by beam formulations that assume strain components to remain small, although arbitrarily large motions are taken into account properly. A formulation of beam theory that includes higher-order strain effects in an approximate manner is developed and numerical examples are presented. The “Saint-Venant problem” refers to a three-dimensional beam loaded at its end sections only. The “Almansi-Michell problem” refers to a three-dimensional beam loaded by distributed body forces, lateral surface tractions, and forces and moments at its end sections. Numerical examples of beams subjected to distributed loads will be presented and compared with 3D finite element solutions.

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