Natural frequencies describe the pre-stress in tensegrity structures

Ashwear, Nasseradeen; Eriksson, Anders

doi:10.1016/j.compstruc.2014.01.020

Cited by 59 publications

(39 citation statements)

References 21 publications

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“…Thus, the finite elements used in simulations must have the capability to capture both axial and transversal vibration in order to give the full dynamic response properties at a particular state. In previous work, we have used Euler-Bernoulli beam elements, in which one-way coupling is introduced to include the effect of the axial force on the transversal stiffness, [7,15]. This addition will allow the representation of not only vibration modes resulting from axial component vibration, but also bending-type modes…”

Section: Finite Element Formulationmentioning

confidence: 99%

“…As the aim here is to design for VHM purposes, simulations must be able to capture all these mentioned characteristics. The development of the finite element formulation will not be further discussed here, but can be found in [7,9,15].…”

Section: Finite Element Formulationmentioning

confidence: 99%

“…The discussion here is based on generating R(ω) of the tensegrity structure based on its mass M and tangent stiffness matrices K T , evaluated at equilibrium as explained in [7], where it is noted that the vibrations will be seen as linearized around a specified equilibrium configuration. This can be the unstressed or an externally loaded situation, but here primarily the prestressed but otherwise unloaded state is considered.…”

Section: Pre-measurement Analysismentioning

confidence: 99%

“…Thus, any change in any component status (tension in the cables or compression in the bars) will be reflected in the levels of pre-stress in all components of the whole structure. Therefore, the natural frequencies of the structure are functions of the level of pre-stress [4][5][6][7]. In the design of large and complex structures, a Form-Finding methods is commonly adapted [8][9][10].…”

Section: Introductionmentioning

confidence: 99%

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Vibration health monitoring for tensegrity structures

Ashwear

Eriksson

2017

Mechanical Systems and Signal Processing

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Tensegrities are assembly structures, getting their equilibrium from the integrity between tension in cables and compression in bars. During their service life, slacking in their cables and nearness to buckling in their bars need to be monitored to avoid a sudden collapse. This paper discusses how to design the tensegrities to make them feasible for vibrational health monitoring methods. Four topics are discussed; suitable finite elements formulation, pre-measurements analysis to find the locations of excitation and sensors for the interesting modes, the effects from some environmental conditions, and the pre-understanding of the effects from different slacking scenarios.

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Section: Finite Element Formulationmentioning

confidence: 99%

Section: Finite Element Formulationmentioning

confidence: 99%

Section: Pre-measurement Analysismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Vibration health monitoring for tensegrity structures

Ashwear

Eriksson

2017

Mechanical Systems and Signal Processing

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“…If a structure is identified as a statically and/or kinematically indeterminate assembly, this implies that the mechanical behavior of this structure is highly relevant to selfstress states (Chen et al, 2014). Especially, the rigidity and the pre-stability of this structure is the result of a self-stress equilibrium between cables and struts (Ashwear and Eriksson, 2014).the concepts of static and the kinematic indeterminacy was derived from these basic theories and regarded as an effective method for system identification. However, this evaluation took no account of the influence of material properties on the mechanical behavior, as well as the contribution of each component to the total degree of indeterminacy.…”

Section: Introductionmentioning

confidence: 99%

Distributed indeterminacy evaluation of cable-strut structures: formulations and applications

Zhou

Chen

Zhao

et al. 2015

J. Zhejiang Univ. Sci. A

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Abstract:The indeterminacy evaluation is an effective method for system identification; it can predict the mechanical behaviors of flexible structures in the primary design. However, the conventional indeterminacy evaluation based solely on geometry and topology has neglected the influence of material properties on mechanical behavior and the contribution of each component to the total indeterminacy. To address these issues, a distributed indeterminacy evaluation taking account of the effect of component stiffness was carried out with a view to providing reasonable interpretations and feasible applications for two concepts, i.e., the distributed static indeterminacy (DSI) and the distributed kinematic indeterminacy (DKI). A unified method for the DSI is proposed, and a comparative analysis between this and an existing method revealed that the proposed method has a wider range of applicability and is essentially identical in the kinematically determinate case. It can be concluded that since the DSI is representative of symmetric properties, a simple but efficient grouping criterion can be established which can improve the efficiency of the specific force finding method entitled double singular value decomposition (DSVD). On the other side, an evaluable method for the DKI is proposed suggesting that DKI is a useful indicator for the assessment of nodal mobility and can provide a feasible solution to the form transforming study.

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Damage Detection in Tensegrity Using Interacting Particle-Ensemble Kalman Filter

Aswal

Sen

Mevel

2021

Lecture Notes in Civil Engineering

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Tensegrity structures form a special class of truss with dedicated cables and bars, that take tension and compression, respectively. To ensure equilibrium, the tensegrity members are required to be prestressed. Over prolonged usage, the cables may lose their prestress while bars may buckle, affecting the structural stiffness as well as its dynamic properties. The stiffness of tensegrities also vary with the load even in the absence of damage. This can potentially mask the effect of damage leading to a false impression of tensegrity health. This poses a major challenge in tensegrity health monitoring especially when the load is stochastic and unknown.Present study develops a vibration based output-only time-domain approach for monitoring the health of any tensegrity in the presence of uncertainties due to ambient force and measurement noise. An Interacting Particle Ensemble Kalman Filter (IPEnKF) has been used that can efficiently monitor tensegrity health from contaminated response data. IPEnKF combines a bank of Ensemble Kalman Filters to estimate response states while running within a Particle Filter envelop that estimates a set of location based health parameters. Further to make damage detection cheaper, strain responses are used as measurements. The efficiency of the proposed methodology has been demonstrated using numerical experiments performed on a simplex tensegrity.

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Natural frequencies describe the pre-stress in tensegrity structures

Cited by 59 publications

References 21 publications

Vibration health monitoring for tensegrity structures

Vibration health monitoring for tensegrity structures

Distributed indeterminacy evaluation of cable-strut structures: formulations and applications

Damage Detection in Tensegrity Using Interacting Particle-Ensemble Kalman Filter

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