Vibration fatigue using modal decomposition

Mršnik, Matjaž; Slavič, Janko; Boltežar, Miha

doi:10.1016/j.ymssp.2017.03.052

Cited by 71 publications

(25 citation statements)

References 27 publications

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“…Hence, modal analysis was proposed to determine the structure resonant frequency prior to the vibration fatigue analysis. In terms of fatigue numerical analysis, the vibration excitation is applied via the frequency-response functions (FRFs) in order to obtain the distribution of the stress or strain tensor in the frequency domain for the automotive structure [20]. Apart from that, the loading power spectra density counter method was also developed to improve the accuracy of vibration fatigue life predictions [21].…”

Section: Introductionmentioning

confidence: 99%

Vibration Fatigue Analysis of Carbon Steel Coil Spring under Various Road Excitations

Kong

Abdullah

Schramm

et al. 2018

Metals

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This paper presents the evaluation of frequency-based approach predicted spring using acceleration signals that were collected from various road conditions. Random loadings in the forms of acceleration are nominal and more flexible for vehicle components fatigue assessment. In this analysis, the strain time history of the spring and acceleration signals of the suspension strut was measured from three different road conditions. The acceleration signals were then transformed into power spectra density (PSD). PSD cycle counter, like Lalanne, Dirlik, and narrow band approach, was applied to obtain equivalent load cycles. The stress response was obtained through having the equivalent load cycles with a spring modal frequency response function (FRF) and different stress criterion, like absolute maximum principal and critical plane approaches. Then, the stress response was used to predict the spring fatigue life using stress-life (S-N) approach. The results revealed that the harshest road condition was the rural road where the spring with fatigue life of 4.47 × 107 blocks to failure was obtained. The strain predicted fatigue life was used to validate the frequency-based predictions using a conservative approach. It was found that the Dirlik approach has shown the closest results to the strain life approach, which suggested that the Dirlik approach could be used for spring fatigue life prediction with the acceptable accuracy.

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Section: Introductionmentioning

confidence: 99%

Vibration Fatigue Analysis of Carbon Steel Coil Spring under Various Road Excitations

Kong

Abdullah

Schramm

et al. 2018

Metals

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“…To target the individual needs of new vehicle customers more directly [15], the number of model derivatives offered by vehicle manufacturers has increased markedly. Designers should assess whether or not a design of model derivatives matches new specifications [16] and [17] by carrying out extra analyses (e.g. system identification).…”

Section: Designing Vehicle Structuresmentioning

confidence: 99%

Active Structural Derivator in the Design Crystallization Phase of L7e Vehicle Structures

Jedrzejczyk¹,

Alb²

2019

SV-JME

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Over the past years, engineers have begun to apply topology optimization (TO) to obtain the first design proposals for new structures. Consequently, designers need to transform the bionic shapes of the TO results into manufacturable geometry that employs the available body-in-white structure types (BSTs) and affirms the efficient and suitable lightweight design. The lack of standardized methodologies, however, forces designers to transform the bionic shapes of the TO subjectively, which results in insufficient and inadequate design proposals. Many different separate geometrical transitions that attempt to transform the TO results into the one of the selected BSTs make the design process even more difficult to manage. For this reason, we have proposed the active structural derivator (ASD) as an extension of our existing integrative CAE-driven design process (ICDDP). The ASD allows for the smooth transition of the TO results and the practical assessment of the selected BSTs such as tubular space frame, space frame, hybrid structure, unibody and monocoque. Our ASD simultaneously employs the size and free-size optimizations under the specific steering criteria within one simulation model, which consists of fundamental engineering-based geometry (beams and plates), to generate the design concepts of the different BSTs for given sets of different requirements. We present the results of our ASD for the new structure of an electrified eQuad vehicle that reveal the ASD's ability to select, allocate and optimize various beam types (arbitrary and defined) together with the plate (shell) geometry. The results assert that the ASD enables engineers to deliver new applicable and lightweight structures.

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“…Continuing from stress response PSD ( ) an equivalent stress PSD ( ) can be quickly obtained [22]. To employ frequency methods for fatigue calculation, -th spectral moment should be defined [7]:…”

Section: Damage Accumulationmentioning

confidence: 99%

“…Thus, when dealing with vibration fatigue of structure under random vibration loads the counting methods in frequency domain (Dirlik [3], Tovo-Benasciutti [4]) are significantly more applicable, computationally effective and faster [5] compared to counting methods in time domain (rainflow, range count), especially when long time-histories need to be evaluated. Fatigue life estimation with frequency counting method is based on power spectral density (PSD) function of structure's stress response and properties of multiaxial stress criterion [6,7]. Inherently to this, a frequency counting methods assume signal's stationarity [8].…”

Section: Introductionmentioning

confidence: 99%

The relevance of non-stationarities and non-Gaussianities in vibration fatigue

et al. 2018

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In classical fatigue of materials, the frequency contents of dynamic loading are well below the natural frequencies of the observed structure or test specimen. However, when dealing with vibration fatigue the frequency contents of dynamic loading and structure's dynamic response overlap, resulting in amplified stress loads of the structure. For such cases, frequency counting methods are especially convenient. Gaussianity and stationarity assumptions are applied in frequency-domain methods for obtaining dynamic structure's response and frequency-domain methods for calculating damage accumulation rate. Since it is common in real environments for the structure to be excited with non-Gaussian and non-stationary loads, this study addresses the effects of such dynamic excitation to experimental time-to-failure of a structure. Initially, the influence of non-Gaussian stationary excitation is experimentally studied via excitation signals with equal power density spectrum and different values of kurtosis. Since no relevant changes of structure's time-to-failure were observed, the study focused on non-stationary excitation signals that are also inherently non-Gaussian. The non-stationarity of excitation was achieved by amplitude modulation and significantly shorter times-to-failure were observed when compared to experiments with stationary non-Gaussian excitation. Additionally, the structure's time-to-failure varied with the rate of the amplitude modulation. To oversee this phenomenon the presented study proposes a non-stationarity index which can be obtained from the excitation time history. The non-stationarity index was experimentally confirmed as a reliable estimator for severity of non-stationary excitation. The non-stationarity index is used to determine if the frequencydomain methods can safely be applied for time-to-failure calculation.

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Vibration fatigue using modal decomposition

Cited by 71 publications

References 27 publications

Vibration Fatigue Analysis of Carbon Steel Coil Spring under Various Road Excitations

Vibration Fatigue Analysis of Carbon Steel Coil Spring under Various Road Excitations

Active Structural Derivator in the Design Crystallization Phase of L7e Vehicle Structures

The relevance of non-stationarities and non-Gaussianities in vibration fatigue

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