A Space‐Time Finite Element Model for Design and Control Optimization of Nonlinear Dynamic Response

Moita, P.P.; Cardoso, J.B.; Valido, A.J.

doi:10.1155/2008/721760

Cited by 3 publications

(6 citation statements)

References 8 publications

(7 reference statements)

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“…In Cardoso et al (2010), the reduced feasible region (or ε -constraint) is used and a min-max upper bound multicriteria strategy to optimize injury prevention systems with preview control is applied. To find the preview time, it used the same idea as in Moita et al (2008) and Cardoso et al (2008) for minimum time problems. In Kent et al (2007), a limiting performance analysis of a restraint system in an automobile impact is made, and ways to its implementation are suggested.…”

Section: Introductionmentioning

confidence: 99%

“…A set of functionals is deﬁned as objectives corresponding to injury criteria which must be kept lower than a safety value for the driver. The dynamic response is modeled via time finite elements, and is solved by at-once integration instead of the traditional step-by-step integration, easing the implementation of displacement, velocity and acceleration conditions at any point in time (Moita et al , 2008). The optimal control force and the pre-acting time are found by the direct multisearch (DMS) solver.…”

Section: Introductionmentioning

confidence: 99%

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Optimal multiobjective design of a vehicle restraint system using pre-acting control

Moita¹,

Madeira²,

Valido³

et al. 2018

MMMS

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Purpose The purpose of this paper is to perform the limiting performance analysis of a vehicle restraint system (seat belt) in order to find the optimal control force, and its pre-acting time that minimizes the risk of injury. Design/methodology/approach A discrete model of the human thorax is used. A multiobjective optimum design problem is formulated in order to minimize the risk of injuries in case of impact. Several injury criteria are minimized and are required to remain below a safety threshold value. Findings The authors found which of the objectives are contradictory and which are not. Several of the optimal sets of design variables are analyzed and their performance compared to one another. The results are also compared to the case of not taking in account the pre-acting time. As expected, the results in this case are worse. Research limitations/implications As with all limiting performance analysis, the technological implementation restraints of the control force are not taken into account. As such, the solutions must be considered a benchmark to which the actual solution can be compared to. Practical implications The limiting performance analysis concept allows us to have a theoretical benchmark to which the real control performance can be compared to. Originality/value As far as the authors know, the pre-acting time, and its implications on the improvement of the performance of the control system, is an original contribution to the problem the authors tried to solve.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Optimal multiobjective design of a vehicle restraint system using pre-acting control

Moita¹,

Madeira²,

Valido³

et al. 2018

MMMS

View full text Add to dashboard Cite

show abstract

“…As the theory and methods of nonlinear structural analysis have progressed, there is no distinction between flexible mechanical systems and structures. Also, in the last decades there has been the integration of optimal design and optimal control problems [3][4][5][6][7].…”

Section: Introductionmentioning

confidence: 99%

“…Both types are designated here as design variables. The systems are discretized by space-time finite elements and the dynamic response is obtained by at-once integration as it is typical for the static response [3]. As it is known from system analysis, the boundary conditions may be imposed easily at any point of the system.…”

Section: Introductionmentioning

confidence: 99%

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Multicriteria Optimization of Injury Prevention Systems to Impact

Cardoso

Moita

Valido

2010

Shock and Vibration

Self Cite

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A sensitivity analysis and multicriteria control optimization formulation is derived for mechanical systems. This formulation is implemented into an interactive optimum design code and it is applied to optimize protection systems for the prevention of injuries. The limiting isolation capabilities of the systems are determined. The effect of pre-acting control is investigated. Control forces as well as the time at which the control should act before the instant of impact are considered as design variables. The same idea used by the authors in previous articles for minimum time control problems is applied here to find the preview time. Dynamic response index, maximum acceleration, rattlespace, or maximum power of the resisting force among others can be used as performance criteria. In order to handle the multicriteria problem, both the reduced feasible region method and a min-max upper bound method are utilized. The adjoint system approach is used to calculate the sensitivities. The dynamic response of the systems and its sensitivity are discretized via space-time finite elements. The equations of motion and the sensitivity equations are integrated at-once as it is typical for the static response. This way, displacement, velocity or acceleration control conditions can be imposed easily at any point in time. Also, adjoint system response is obtained without needing primary response memorization. Mathematical programming is used for the optimal control process.

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Optimal Design and Control of Mechanical Systems with Uncertain Input

Moita

Cardoso

Barreiros

2012

Shock and Vibration

Self Cite

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This paper presents an integrated approach to optimize for design and control of mechanical systems with random input parameters. Random parameters are represented by probability density functions. A numerical technique defining directly the representative values and the associated probabilities is implemented by modeling the stochastic parameters as generalized Wiener processes. The Monte Carlo's method is also implemented to deal with correlated parameters. A design and control sensitivity analysis optimization formulation is derived. A conceptual separation between time variant and time invariant design parameters is presented, this way including the design space into the control space and considering the design variables as control variables not depending on time. By using time integrals through all the derivations, the design and control problems are unified.In the optimization process we can use both types of variables simultaneously or by interdependent levels. The dynamic response is modeled via space and time finite elements, and is integrated either by at-once integration or step-by-step. The formulation is applied to a numerical example.

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A Space‐Time Finite Element Model for Design and Control Optimization of Nonlinear Dynamic Response

Cited by 3 publications

References 8 publications

Optimal multiobjective design of a vehicle restraint system using pre-acting control

Optimal multiobjective design of a vehicle restraint system using pre-acting control

Multicriteria Optimization of Injury Prevention Systems to Impact

Optimal Design and Control of Mechanical Systems with Uncertain Input

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