Dynamic Snap-Through of Thin-Walled Structures by a Reduced-Order Method

Przekop, Adam; Rizzi, Stephen A.

doi:10.2514/1.26351

Cited by 73 publications

(20 citation statements)

References 15 publications

(21 reference statements)

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“…Because the linear stiffness terms are functions of temperature, their evaluation must be performed at the temperature condition analyzed, even though the particular set of normal modes used is the same. 13 In the following, two temperature conditions are analyzed. Therefore, four stiffness evaluations are performed under the following conditions; stress-free modes at ambient temperature, stress-free modes at elevated temperature, prestressed modes at ambient temperature, and pre-stressed modes at elevated temperature.…”

Section: Numerical Examplementioning

confidence: 99%

“…It is known, however, that for planar and isotropic structures, only linear coefficients d depend on the temperature increment ΔT. 13 Different combinations of scaled NMs are used to form a set of prescribed displacement fields. The normal mode vectors are scaled by the generalized coordinates { to obtain physically meaningful magnitudes.…”

Section: Nonlinear Reduced-order Analysismentioning

confidence: 99%

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Nonlinear Reduced-Order Simulation Using Stress-Free and Pre-Stressed Modal Bases

Przekop

Stover

Rizzi

2009

50th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference

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A study is undertaken to determine the advantages and disadvantages associated with application of stress-free and pre-stressed modal bases in a reduced-order finite-elementbased nonlinear simulation. A planar beam is chosen as an application example and its response due to combined thermal and random pressure loadings is examined. Combinations of two random pressure levels and two thermal conditions are investigated. The latter consists of an ambient temperature condition and an elevated temperature condition in the post-buckled regime. It is found that stress-free normal modes establish a broadly applicable modal basis yielding accurate results for all the loading regimes considered. In contrast, the range of applicability for a thermally pre-stressed modal basis is found to be limited. The behavior is explained by scrutinizing the coupling found in the linear stiffness and the effect this coupling has on the structural response characteristics under the range of loading conditions considered.

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Section: Numerical Examplementioning

confidence: 99%

Section: Nonlinear Reduced-order Analysismentioning

confidence: 99%

Nonlinear Reduced-Order Simulation Using Stress-Free and Pre-Stressed Modal Bases

Przekop

Stover

Rizzi

2009

50th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference

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“…For the 19.44°C (35°F) temperature increment, application of the thermal loading in this manner produced a transient thermal buckling response. 2 In the remainder of the paper, the combined load case is specified via the shorthand notation x°F/y dB, where x is the temperature increment and y is the random pressure level.…”

Section: δTmentioning

confidence: 99%

“…For this condition, increasing sound pressure level was previously shown to evolve the response from vibration around one of the positions, to intermittent snap-through and finally to persistent snap-through between the two equilibrium positions. 2 For each non-zero temperature increment case, the thermal load was applied instantaneously at the beginning of each simulation. For the 19.44°C (35°F) temperature increment, application of the thermal loading in this manner produced a transient thermal buckling response.…”

Section: δTmentioning

confidence: 99%

An Investigation of High-Cycle Fatigue Models for Metallic Structures Exhibiting Snap-Through Response

Przekop

Rizzi

Sweitzer³

2007

48th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference

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A study is undertaken to develop a methodology for determining the suitability of various high-cycle fatigue models for metallic structures subjected to combined thermal-acoustic loadings. Two features of this problem differentiate it from the fatigue of structures subject to acoustic loading alone. Potentially large mean stresses associated with the thermally preand post-buckled states require models capable of handling those conditions. Snap-through motion between multiple post-buckled equilibrium positions introduces very high alternating stress. The thermal-acoustic time history response of a clamped aluminum beam structure with geometric and material nonlinearities is determined via numerical simulation. A cumulative damage model is employed using a rainflow cycle counting scheme and fatigue estimates are made for 2024-T3 aluminum using various non-zero mean fatigue models, including Walker, Morrow, Morrow with true fracture strength, and MMPDS. A baseline zero-mean model is additionally considered. It is shown that for this material, the Walker model produces the most conservative fatigue estimates when the stress response has a tensile mean introduced by geometric nonlinearity, but remains in the linear elastic range. However, when the loading level is sufficiently high to produce plasticity, the response becomes more fully reversed and the baseline, Morrow, and Morrow with true fracture strength models produce the most conservative fatigue estimates. This material is declared a work of the U.S. Government and is not subject to copyright protection in the United States. Nomenclature

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“…Notwithstanding the above difficulties, the ROM capabilities have progressed from applications to flat structures (see [2][3][4][5][6][7][8][9]), to moderately large motions of curved structures (see [10][11][12][13][14]). Further, the coupling of these nonlinear structural reduced order models with aerodynamics, either full or reduced order model has also been successfully demonstrated in [15][16][17].…”

Section: Introductionmentioning

confidence: 99%

Prediction of displacement and stress fields of a notched panel with geometric nonlinearity by reduced order modeling

Perez

Wang

Mignolet

2014

Journal of Sound and Vibration

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The focus of this investigation is on a first assessment of the predictive capabilities of nonlinear geometric reduced order models for the prediction of the large displacement and stress fields of panels with localized geometric defects, the case of a notch serving to exemplify the analysis. It is first demonstrated that the reduced order model of the notched panel does indeed provide a close match of the displacement and stress fields obtained from full finite element analyses for moderately large static and dynamic responses (peak displacement of 2 and 4 thicknesses). As might be expected, the reduced order model of the virgin panel would also yield a close approximation of the displacement field but not of the stress one. These observations then lead to two "enrichment" techniques seeking to superpose the notch effects on the virgin panel stress field so that a reduced order model of the latter can be used. A very good prediction of the full finite element stresses, for both static and dynamic analyses, is achieved with both enrichments.

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Dynamic Snap-Through of Thin-Walled Structures by a Reduced-Order Method

Cited by 73 publications

References 15 publications

Nonlinear Reduced-Order Simulation Using Stress-Free and Pre-Stressed Modal Bases

Nonlinear Reduced-Order Simulation Using Stress-Free and Pre-Stressed Modal Bases

An Investigation of High-Cycle Fatigue Models for Metallic Structures Exhibiting Snap-Through Response

Prediction of displacement and stress fields of a notched panel with geometric nonlinearity by reduced order modeling

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