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Showing papers on "Vibration fatigue published in 2013"


Journal ArticleDOI
TL;DR: In this paper, a comparison of different frequency-domain methods with respect to real experiments that are typical in structural dynamics and the automotive industry is presented, showing that besides the Dirlik approach, the Tovo-Benasciutti and Zhao-Baker methods should be considered as the preferred methods for fatigue analysis in the frequency domain.

216 citations


02 Dec 2013
TL;DR: In this article, the problem of the material fatigue properties estimation for assessing real mechanical components is addressed, and some practical rules are proposed to estimate the plain material fatigue limit (under uniaxial and torsional loadings) and the ElHaddad's short crack constant.
Abstract: This paper addresses the problem of the material fatigue propertiesestimation for assessing real mechanical components. These information are needed toapply the most modern methods capable of assessing components weakened by notchesand defects, subjected to both uniaxial and multiaxial fatigue loadings. In particular, byusing a large database of fatigue data, some practical rules are proposed to estimatethe plain material fatigue limit (under uniaxial and torsional loadings) and the ElHaddad’s short crack constant.

71 citations


Journal ArticleDOI
TL;DR: In this paper, a fatigue driving stress that causes fatigue damage is presented and used to predict residual fatigue life under variable loading, which is a function of the applied cyclic st...
Abstract: A fatigue driving stress that causes fatigue damage is presented and used to predict residual fatigue life under variable loading. This fatigue driving stress is a function of the applied cyclic st...

63 citations


Journal ArticleDOI
TL;DR: In this article, a three-dimensional finite element model (FEM) is developed to predict the progressive fatigue damage with provision for stochastic distribution of material properties, which allows determining the scatter lifespan of mechanical components subjected to low and high cycle fatigue loading.

57 citations


Journal ArticleDOI
TL;DR: In this paper, a probabilistic approach using the weakest link concept is introduced to model the competition between the two fatigue damage mechanisms, depending on the presence of different micro-shrinkage pores, Si particles, Fe-rich intermetallic phases, DAS of the Al-matrix, etc.

45 citations


Journal ArticleDOI
TL;DR: In this article, the authors present a comprehensive framework for fatigue reliability analysis of long-span bridges under combined dynamic loads from vehicles and wind, and the probability of failure for the fatigue damage at the end of each block of stress cycles and the cumulative probability for failure can be obtained.
Abstract: During a bridge’s life cycle, the stresses from multiple dynamic loads might be superposed and progressive fatigue damage might accumulate and induce serious fatigue damage issues. This paper presents a comprehensive framework for fatigue reliability analysis of long-span bridges under combined dynamic loads from vehicles and wind. After modeling the complicated structure details with equivalent orthotropic material, dynamic stress ranges of a long-span bridge are obtained via solving the equations of motion for the vehicle-bridge-wind dynamic system with multiple random variables considered, for instance, vehicle speed, road roughness conditions, and wind velocity and direction. After counting the number of stress cycles at different stress range levels using the rain flow counting method, fatigue damage increments are obtained using the fatigue damage accumulation rule. The probability of failure for the fatigue damage at the end of each block of stress cycles and the cumulative probability of failure can be obtained. As a result, the fatigue life and reliability for the given structure details can be obtained. Based on the results from a case study, the dynamic effects from vehicles are found to be relatively small for long-span bridges and the effects from vehicle speeds and road roughness conditions can be neglected. Nevertheless, even though the stresses from either the vehicle loads or wind loads may not be able to induce serious fatigue problems alone, the superposed dynamic stress ranges cannot be ignored for fatigue reliability assessment of long-span bridges.

43 citations


Journal ArticleDOI
TL;DR: In this paper, the authors present a method dealing with non-Gaussian signals with real statistical properties that is still able to use the efficient PSD approach with its computation time advantages.

39 citations


Journal ArticleDOI
TL;DR: In this paper, the authors investigated the capability of the relative stress gradient to properly represent the beneficial effect of residual stress states on the fatigue life of Ti-6Al-4V specimens, with notches of different severity.
Abstract: The subject of this paper is to investigate the capability of the relative stress gradient to properly represent the beneficial effect of residual stress states on the fatigue life of Ti-6Al-4V specimens, with notches of different severity. The research was developed considering notched and un-notched specimens with different geometries and different shot-peening treatments. The results were determined by running fatigue experimentation under rotating bending and by developing a novel predictive model based on the relationship between the local fatigue limit and a generalized form of the relative stress gradient, accounting for the peening-induced residual stresses. The proposed tool for fatigue limit estimation was completed by a stochastic analysis, which considered the variability of the involved parameters, in particular the residual stress entity. This made it possible to finally determine the component failure probability in a general, efficient and accurate way.

38 citations


Journal ArticleDOI
TL;DR: In this article, a detailed finite element (FE) model of the bridge was established and validated by the dynamic test results, and six types of structural details in the bridge were considered for fatigue evaluation.

37 citations


Journal ArticleDOI
TL;DR: In this paper, a full-scale turbine blade attached to a part of actual turbine disc at elevated temperature was used to predict the life of a fir-tree contact under high cycle fatigue (HCF)/low cycle fatigue combined loading, and the effect of shot peening on the fatigue lives of turbine attachments was investigated experimentally by comparing those of unpeened ones.
Abstract: Purpose – The purpose of this paper is to perform experiments on a full scale turbine blade attached to a part of actual turbine disc at elevated temperature, which can accurately predict the life of a fir‐tree contact under high cycle fatigue (HCF)/low cycle fatigue (LCF) combined loading Moreover, the effect of shot‐peening on the fatigue lives of the turbine attachments is investigated experimentally by comparing those of unpeened onesDesign/methodology/approach – An experimental system for a full scale turbine blade attached to a part of actual turbine disc at elevated temperature is established in this paper, with a new HCF/LCF combined loading scheme and a design of blade clamp The new combined fatigue loading method achieves a noninterfering treatment of the high cycle and low cycle loading by placing low cycle loading exerting point to the back of the mortise Then fatigue tests were performed on six used turbine components to investigate the effect of shot‐peening on fatigue life compared with

35 citations


Journal ArticleDOI
TL;DR: In this article, an evaluation of the fatigue characteristics of a knuckle using a gravel road profile acquired using a data acquisition system and standard SAE profiles for the suspension (SAESUS), bracket (SAEBRAKT), and transmission (SAETRN) is presented.
Abstract: In automobile design, the safety of passengers is of prime concern to the manufacturers. Suspension is one of the safety-related automotive systems which is responsible for maintaining traction between the road and tires, and offers a comfortable ride experience to the passengers by absorbing disturbances. One of the critical components of the suspension system is the knuckle, which constantly faces cyclic loads subjecting it to fatigue failure. This paper presents an evaluation of the fatigue characteristics of a knuckle using a gravel road profile acquired using a data acquisition system and standard SAE profiles for the suspension (SAESUS), bracket (SAEBRAKT) and transmission (SAETRN). The gravel road profile was applied as the input to a multi body simulation (MBS), and the load history for various mounting points of the knuckle is extracted. Fatigue life is predicted using the strain-life method. The instantaneous stress distributions and maximum principal stress are used for fatigue life predictions. From the results, the strut connection is found to be the critical region for fatigue failure. The fatigue life from loading extracted from gravel road MBS agreed well with the life prediction when standard SAE profiles were used. This close agreement shows the effectiveness of the load extraction technique from MBS. This method can also be effectively used for more complex loading conditions that occur during real driving environments.

Journal ArticleDOI
TL;DR: In this paper, a nonlinear fatigue damage assessment approach for existing bridges is presented to include the progressive road surface deterioration and the nonlinear effects of the fatigue damage accumulation due to random dynamic vehicle loads.

Journal Article
TL;DR: In this article, a new approach is developed in order to take into account the stress gradient effect on fatigue life of structural components, which is based on the weakest link concept in which the shape coefficient of the Weibull distribution becomes a function of a local damage parameter.
Abstract: In the present paper, a new approach is developed in order to take into account the stress gradient effect on fatigue life of structural components. The proposed approach is based on the weakest link concept in which the shape coefficient of the Weibull distribution becomes a function of a local damage parameter. The function simulates the experimentally observed relationship between the shape of the fatigue life distribution and the stress level. Such an approach allows one to calculate the global probability distribution of the fatigue life for notched structural components in a wide range of fatigue life regime: $ 10^4$-$10^7$ cycles typically. For comparison purposes, the approach is applied to calculate the number of cycles to crack initiation of structural elements under three probability levels: 5%, 63% and 95%. The calculated lifetimes are compared with the lifetimes obtained from experiments performed on notched cruciform specimens and notched round specimens subjected to constant amplitude loading.

Journal ArticleDOI
TL;DR: In this article, a new stress-life damage accumulation model is proposed, calibrated and validated using two different experimental works available in the literature, called the VTLC, for Virtual Life Target Curves.

Journal ArticleDOI
TL;DR: In this paper, a vibration fatigue analysis that considers changes in frequency response resulting from the cumulative fatigue damage to multi-point spot-welded joints in an automotive body was conducted.

Journal ArticleDOI
TL;DR: In this article, the response of thin rectangular plates to random boundary excitation is analytically formulated and analyzed; the results show that increasing both the modal damping ratio and the excitation frequency range will decrease the root mean square acceleration and the maximum deflection of the plate.
Abstract: Fatigue life, stability and performance of majority of the structures and systems depend significantly on dynamic loadings applied on them. In many engineering cases, the dynamic loading is random vibration and the structure is a plate-like system. Examples could be printed circuit boards or jet impingement cooling systems subjected to random vibrations in harsh military environments. In this study, the response of thin rectangular plates to random boundary excitation is analytically formulated and analyzed. In the presented method, closed-form mode shapes are used and some of the assumptions in previous studies are eliminated; hence it is simpler and reduces the computational load. In addition, the effects of different boundary conditions, modal damping and excitation frequency range on dynamic random response of the system are studied. The results show that increasing both the modal damping ratio and the excitation frequency range will decrease the root mean square acceleration and the maximum deflection of the plate.

Journal ArticleDOI
TL;DR: In this paper, a study of the dissipated energy approach according to two methods, i.e., cumulative energy and the ratio of dissipated energies, was performed, with a double shear cyclic test of asphalt material HMA 0/6 being chosen at a 10-Hz frequency, 10°C and 20°C, at various force or displacement loading levels.

Journal ArticleDOI
TL;DR: In this paper, a nonlinear time-domain hydrodynamic simulations followed by finite element (FE) analyses are used for the fatigue assessment of ship side-shell structures, and the results indicated a shorter fatigue life than the results obtained using the SCF.

Journal ArticleDOI
TL;DR: In this article, a systematic procedure for fatigue damage assessment in relation to ships navigating in ice-covered waters is proposed, where closed form expressions for the fatigue damage based on the Palmgren-Miner's rule are derived for several different statistical models of the stress amplitudes, i.e. the exponential, the Weibull's, and the three-parameter exponential distributions.

Journal ArticleDOI
Jung Hoon Kim1, Jio Yi1, Jihwan Kim1, Goangseup Zi1, Jung Sik Kong1 
TL;DR: In this paper, a novel index was proposed to evaluate an effect for stress interaction by using entropy concept, and fatigue life prediction methodology was developed using entropy index of stress interaction and crack severity index of effective stress.
Abstract: Fatigue life in critical parts of structure components, which is subjected to variable amplitude loading, is a very complex subject. When a fatigue life is influenced by these load variations, accelerations and/or retardations in crack growth rate can occur. Thus, an accurate prediction of fatigue life requires an adequate evaluation of these stress interaction effects. There are many different indexes for calculating fatigue damage at critical locations. The crack severity index based on crack growth is one of the methodologies implemented for modern military aircrafts to define mission severity relative to a known reference usage. But, this index cannot consider stress interaction. In this study, a novel index was proposed to evaluate an effect for stress interaction by using entropy concept, and fatigue life prediction methodology was developed by using entropy index of stress interaction and crack severity index of effective stress.

Journal ArticleDOI
TL;DR: In this article, the tensile fatigue behavior of a high-stressed carbon fiber epoxy-matrix composite laminates is examined at room temperature, where self-heating measurements under cyclic loading allow a fast estimation of fatigue properties of composite materials.

Journal ArticleDOI
TL;DR: In this article, a shaker-based shearing force free bending test stand and a specifically produced fiber reinforced polymers (CFRP) were used for the analysis of the widely unknown damage behavior of CFRP at VHCF-loading.

Journal ArticleDOI
TL;DR: In this paper, a composite blade structure for a 2 MW horizontal axis wind turbine is optimally designed to simultaneously minimize material cost and blade weight while satisfying the constraints on stress ratio, tip deflection, fatigue life and laminate layup requirements.
Abstract: A composite blade structure for a 2 MW horizontal axis wind turbine is optimally designed. Design requirements are simultaneously minimizing material cost and blade weight while satisfying the constraints on stress ratio, tip deflection, fatigue life and laminate layup requirements. The stress ratio and tip deflection under extreme gust loads and the fatigue life under a stochastic normal wind load are evaluated. A blade element wind load model is proposed to explain the wind pressure difference due to blade height change during rotor rotation. For fatigue life evaluation, the stress result of an implicit nonlinear dynamic analysis under a time-varying fluctuating wind is converted to the histograms of mean and amplitude of maximum stress ratio using the rainflow counting algorithm Miner's rule is employed to predict the fatigue life. After integrating and automating the whole analysis procedure an evolutionary algorithm is used to solve the discrete optimization problem.

Journal ArticleDOI
TL;DR: In this article, conditions under which a dynamic analysis should be considered for the fatigue assessment of a bridge are investigated, and the effect of several parameters related to the train and the bridge is studied.

Book ChapterDOI
04 Feb 2013
TL;DR: In this paper, the analysis of fatigue test data from technical literature has shown the possibility of using a critical layer characterizing the microstructural state of the material, and representing the elementary volume acting during the damage process during fatigue loading.
Abstract: The analysis of fatigue test data from technical literature has shown the possibility of using a critical layer characterizing the microstructural state of the material, and representing the elementary volume acting during the damage process during fatigue loading. Combining this parameter with a criterion for multiaxial fatigue gives a new intrinsic fatigue criterion of a material which should allow the computation of fatigue life of notched parts under multiaxial stresses. Further experimental work is needed to fully validate this model.

Journal ArticleDOI
TL;DR: In this paper, fatigue-related mechanical failures in variable-frequency drive (VFD) motor machinery due to mechanical vibrations excited by drive torque harmonics which are created by pulse width modulation (PWM) switching are investigated.
Abstract: This paper documents fatigue-related mechanical failures in variable-frequency drive (VFD) motor machinery due to mechanical vibrations excited by drive torque harmonics which are created by pulse width modulation (PWM) switching. Present effort models the coupled system with a full electrical system (including the rectifier, dc bus, inverter, and motor), and an industrial mechanical system (including flexible couplings, gearboxes, and multiple inertias). The models are formed by a novel combination of a commercial motor code with a general self-written mechanical code. The approach extends failure prediction beyond the simple occurrence of resonance to fatigue life evaluation based on the rain-flow algorithm, which is suitable for both steady state and transient start-up mechanical response. The second contribution is a demonstration that the common use of a multilevel inverter to reduce voltage/current harmonics may actually exacerbate resonance and fatigue failure. This is shown to be caused by a resulting amplitude increase of torque components in proximity to potential resonance frequencies.

Journal ArticleDOI
TL;DR: In this article, the authors tried to provide a comprehensive probability model of fatigue crack initiation prediction in railhead of joint area by using of FEM, response surface method, probability theory and reliability analysis.

Journal ArticleDOI
TL;DR: In this paper, the capabilities of Rainflow cycle counting procedure, maximum principal strain as a damage criterion, and Miner's linear cumulative damage rule are evaluated with both specimen and component tests.
Abstract: Elastomeric components are widely used in many applications due to their good damping and energy absorption characteristics. The type of loading normally encountered by these components in service is variable amplitude cyclic loading. Therefore, fatigue failure is a major consideration in their design. In this work capabilities of Rainflow cycle counting procedure, maximum principal strain as a damage criterion, and Miner's linear cumulative damage rule are evaluated with both specimen and component tests. An automotive cradle mount is used as an illustrative component. Comparison of predicted and experimental fatigue lives in both specimen and cradle mount variable amplitude load tests indicate satisfactory predictions in both cases.

01 Jul 2013
TL;DR: In this paper, a non-Gaussian excitation signal with a given power spectral density and kurtosis is generated for a linear time invariant system and an algorithm is presented that determines the output kurtotic of the signal based upon the input Kurtosis, the input power spectral densities and the frequency response function of the system.
Abstract: High cycle fatigue of metals typically occurs through long term exposure to time varying loads which, although modest in amplitude, give rise to microscopic cracks that can ultimately propagate to failure. The fatigue life of a component is primarily dependent on the stress amplitude response at critical failure locations. For most vibration tests, it is common to assume a Gaussian distribution of both the input acceleration and stress response. In real life, however, it is common to experience non-Gaussian acceleration input, and this can cause the response to be non-Gaussian. Examples of non-Gaussian loads include road irregularities such as potholes in the automotive world or turbulent boundary layer pressure fluctuations for the aerospace sector or more generally wind, wave or high amplitude acoustic loads. The paper first reviews some of the methods used to generate non-Gaussian excitation signals with a given power spectral density and kurtosis. The kurtosis of the response is examined once the signal is passed through a linear time invariant system. Finally an algorithm is presented that determines the output kurtosis based upon the input kurtosis, the input power spectral density and the frequency response function of the system. The algorithm is validated using numerical simulations. Direct applications of these results include improved fatigue life estimations and a method to accelerate shaker tests by generating high kurtosis, non-Gaussian drive signals.

Journal ArticleDOI
TL;DR: In this paper, a new method and new relationships for fatigue life calculation is proposed taking into account the superposition of fatigue loadings, considering the dependence of critical stress value on the number of loading cycles, as well as the nonlinear behaviour of the material along with the influence of the mean stress, cyclic loads rate and deteriorations.