Review of Response and Damage of Linear and Nonlinear Systems under Multiaxial Vibration

Habtour, Ed; Connon, William; Pohland, Michael F.; Stanton, Samuel C.; Paulus, Mark; Dasgupta, Abhijit

doi:10.1155/2014/294271

Cited by 31 publications

(21 citation statements)

References 117 publications

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“…The softening in the dynamic beam response, observed in the nonlinear dynamic experiments as a results of fatigue damage precursor, is captured in the analytical model by adjusting the nonlinear geometric stiffness term, K * in the equation of motion, Eqn (18). Minor adjustments were also made to the viscous damping term, c, to match the response amplitude for each test.…”

Section: Model Resultsmentioning

confidence: 99%

“…Nonlinearity in the dynamic response of structures can be instigated by material properties such as nonlinear constitutive relations [14,15], nonideal boundary conditions [16,17], complex multiaxial loading [18], damping mechanisms [19], and large-deformation kinematics (geometric nonlinearity) with inertial effects [20]. Geometric nonlinearity arises from nonlinear strain-displacement relations for large deformations and produces a nonlinear stiffening effect that appears in many engineering applications [21,22].…”

Section: Nonlinear Dynamics Of Undamaged and Damaged Structuresmentioning

confidence: 99%

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Detection of fatigue damage precursor using a nonlinear vibration approach

Habtour

Cole

Riddick

et al. 2016

Struct. Control Health Monit.

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SUMMARYA nonlinear dynamic methodology is developed for detecting and estimating fatigue damage precursor in isotropic metal structures, prior to fatigue crack initiation, based on measurement of changes in the structure nonlinear response to harmonic base excitation. As an example, a damage precursor feature was extracted for cantilever beams by quantifying the reduction in the nonlinear stiffness because of localized microscopic material softening. The nonlinear dynamic analytical model parametrically tracks changes in the nonlinear structural stiffening as a function of the structural response and the loading cycles. Experimental results are obtained by exciting the base of cantilever beams at various amplitude levels. At high response amplitudes, the beams experience three competing simultaneous nonlinear dynamic mechanisms: (i) stiffening because of high response amplitude at the fundamental mode; (ii) softening because of inertial forces; and (iii) softening because of localized microscopic material damage caused by cyclic micro-plasticity. The third mechanism-a potential precursor to fatigue crack initiation in the structure-resulted in a cumulative softening because of early accumulation of cyclic fatigue damage and is the focus of this study. The loading intensity and the number of cycles influenced the relative contribution of these dynamic mechanisms. Nanoindentation studies near the beam clamped boundary were conducted to confirm the fatigue degradation in the local mechanical properties as a function of loading cycles. The proposed detection method is simple to implement and detects the presence of damage precursors but lacks the resolution to discern spatial distributions of the damage intensity. Based on prior knowledge of the structural dynamic characteristics of the beam and using the proposed methodology, damage level and stiffness reduction can be detected and estimated based on changes in the nonlinear structural response. The nonlinear stiffness term in the equation of motion is found to be very sensitive to the proposed fatigue damage precursor, making it an effective method for monitoring structural degradation prior to crack developments. The proposed methodology provides new insights and constitutes a significant step toward the development of new inspection techniques.

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Section: Model Resultsmentioning

confidence: 99%

Section: Nonlinear Dynamics Of Undamaged and Damaged Structuresmentioning

confidence: 99%

Detection of fatigue damage precursor using a nonlinear vibration approach

Habtour

Cole

Riddick

et al. 2016

Struct. Control Health Monit.

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“…For this reason, the analysis of engineering metallic structures under multiaxial variable amplitude loadings is very challenging, still open and worthy of investigation . The dynamic loads in most engineering systems such as ground and aerial vehicles are intrinsically random . Therefore, characterizing vibration‐fatigue strength and life is imperative in performing both mechanical design and structural dynamic analysis .…”

Section: Introductionmentioning

confidence: 99%

“…[1][2][3] The dynamic loads in most engineering systems such as ground and aerial vehicles are intrinsically random. 4 Therefore, characterizing vibration-fatigue strength and life is imperative in performing both mechanical design and structural dynamic analysis. 5,6 In general, the dynamic analysis can efficiently be conducted in the frequency domain, particularly when the vibration loads are random.…”

Section: Introductionmentioning

confidence: 99%

Methodology for assessing embryonic cracks development in structures under high‐cycle multiaxial random vibrations

Vantadori

Haynes

Fortese

et al. 2017

Fatigue Fract Eng Mat Struct

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A B S T R A C T The myriad applicability of the frequency-domain critical plane criterion is outlined in order to evaluate and track the progression of fatigue damage in metallic structures subjected to high-cycle multiaxial random vibrations. The fatigue assessment using the given criterion is performed according to the following stages: (i) critical plane definition, (ii) power spectral density evaluation of an equivalent normal stress and (iii) computation of the damage precursor and fatigue life. The frequency-domain critical plane criterion is validated using experimental results related to (a) AISI 1095 steel cantilever beams under nonlinear base vibration, (b) 18G2A steel and (c) 10HNAP steel round specimens under random non-proportional combined flexural and torsional loads.Keywords damage precursor; frequency domain; high-cycle fatigue; multiaxial loading; random loading; vibration fatigue. Z ' = rotated frame Puvw = reference system related to the critical plane S eq (ω) = equivalent PSD function s xyz (t) = stress vector in PXYZT = time interval of observation T cal = fatigue life determined through calculations T exp = fatigue life through experiments α n = nth bandwidth parameter, with n = 1,2,3, … γ = rotation about the w axiŝ 1;2 and3 = rotation about the X ' axis λ n = nth spectral moment, with n = 1,2,3, … σ af = fatigue limit for fully reversed normal stress (R = À 1) σ 2 6';6' = variance of s 6 ' t ð Þ σ 2 6};6} = variance of s 6 } t ð Þ τ af = fatigue limit for fully reversed shear stress (R = À 1) ω = pulsation Correspondence: S. Vantadori.

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“…The formulations that approximate the translation does not usually provide a wide applicability range, leading to unacceptable errors when the characteristic parameters assume values out from the range for which the method has been optimized [28][29][30]. It is rather obvious that, in view of the development of a frequency domain approach, alternative to the time domain reference criterion (RFC), it is necessary to cover the largest possible domain of random process typology.…”

Section: Introductionmentioning

confidence: 99%