共查询到20条相似文献,搜索用时 15 毫秒
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N. Nguyen M. Bacher‐Höchst C. M. Sonsino 《Materialwissenschaft und Werkstofftechnik》2011,42(10):904-908
This paper presents a probabilistic method for fatigue life estimation within the frequency domain for structural elements subjected to multiaxial random loadings. Multivariate Monte Carlo Simulation is used to account for the correlation between the stress components and their different probability of occurrence and, moreover, enables stochastics during damage analysis to be allowed for and, at the same time, uses any suitable, material dependent multiaxial fatigue criterion known from the time domain. Comparison of the evaluated fatigue damage with experimental results from vibration tests on a demonstrator, chosen from common application fields in the automobile industry, shows good correlation. 相似文献
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The purpose of this paper is to discuss the recent developments in multi-axial spectral methods, used for estimating fatigue damage of multi-axial random loadings from Power Spectral Density (PSD) data. The difference between time domain and frequency domain approaches in multi-axial fatigue is first addressed, the main advantages of frequency domain approach being pointed out. The paper then critically reviews some categories of multi-axial spectral methods: approaches based on uniaxial equivalent stress (strength criteria, “equivalent von Mises stress”, multi-axial rainflow counting), critical plane criteria (Matake, Carpinteri-Spagnoli, criterion based on resolved shear stress on critical plane), stress-invariants based criteria (Crossland, Sines, “Projection-by-Projection”). The “maximum variance” method and the Minimum Circumscribed Circle/Ellipse formulations defined in the frequency domain are also discussed. The paper critically analyses also non-proportional multi-axial loadings and the role of material fatigue parameters (e.g. S/N curves for bending/torsion) in relation to specific methods. The paper concludes with general comments on advantages and possible limitations in the use of multi-axial spectral methods, with special focus on the assumption of stationarity and Gaussianity in modelling multi-axial random loadings. 相似文献
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Based on a probabilistic model of strength-lifetime, an approach to estimating simple fatigue reliability by using first-order reliability techniques is presented. By this approach the results of life testing at two stress levels can be used directly to estimate simple fatigue reliability corresponding to any lifetime and applied stress ratio. Using the approach does not need the data of a fatigue strength staircase test which are not exact enough for describing the distribution of fatigue strength and can only be used for a specific lifetime. A numerical example is given to show the application of the approach. 相似文献
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Wave-loading fatigue failure is one of main failure modes of deepwater drilling riser. Wave-loading fatigue analysis of riser provides guidance for fatigue design and management of riser in order to increase its service life. Methods for analyzing wave induced vibration and fatigue were established in frequency domain. Solver for riser fatigue calculation was developed based on MATLAB software. Wave-loading fatigue of the riser system in the South China Sea was calculated in frequency domain and compared with calculated fatigue based on time domain method. The results show that dynamic analysis of riser in frequency domain reaches convergence after several iteration steps. Compared with time domain method, frequency domain method enhances computation efficiency greatly. The response of riser system is a wide-band process so rainflow correction coefficient should be used in calculating riser fatigue. The wave-loading fatigue damage of riser in frequency domain is almost same with that in time domain. Riser fatigue analysis method proposed in this paper can be used for inertial fatigue analysis. 相似文献
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Fatigue analysis of mechanical components subjected to random loads has been recently upgraded through several developments of calculation procedures, with the scope to support the designer within the loading condition numerical simulation. Under such scenario, the frequency domain approach is characterized by interesting features, which support its adoption in alternative or in conjunction with the classic time-domain approach, especially when the frequency domain is applied for the individuation of the component critical locations. The major goal of this paper consists of an overview about the strength and weaknesses of frequency approach with respect to the time domain one by comparing the reference time domain methods with their frequency domain translation. A significant test case development will be shown, representing a classic automotive one (chassis validation). Promising results of the frequency method application will be presented, encouraging its adoption on large scale. 相似文献
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Qinghua Han Jia Li Jie Xu Fei Ye Alberto Carpinteri Giuseppe Lacidogna 《Fatigue & Fracture of Engineering Materials & Structures》2019,42(1):97-113
A new frequency domain method for random fatigue life estimation in a wide‐band stationary Gaussian random process was proposed for application in fatigue analysis. Simulations of the power spectral densities of different types were firstly performed; the simulated results showed that the accuracy and applicability for the current frequency domain methods are not only related to the spectral type but also associated with the types of the analysed materials. Compared with the current methods, the proposed method, in which the rain‐flow amplitude obeys Nakagami distribution, has better universality and could significantly reduce the error for the random fatigue life estimation with simulated and actual spectra. Verified application in cast‐steel fatigue life analysis were performed between random fatigue life and constant amplitude fatigue life. It is shown that the fatigue life analysis under random load cannot be ignored and the proposed new method can serve as a recommended method. 相似文献
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Alfredo R. de Faria Srgio Frascino M. de Almeida 《International journal for numerical methods in engineering》2006,65(4):445-460
A general technique is proposed to maximize the lowest natural frequency of structures subjected to an arbitrary state of initial stresses. The arbitrary states of initial stresses are represented by nondimensional loading parameters that describe an admissible loading space, i.e. every possible initial stress state lies within the admissible loading space. The key to the proposed optimization strategy is shown to be the concavity of the first natural frequency with respect to variations of the loading parameters within the admissible loading space. A rigorous demonstration is presented to show that, provided buckling has not occurred, all the possible initial stress states must not be considered. Instead, assessment of only a small number of initial stress states must be done in order to guarantee that the first natural frequency does not decrease for all the other initial stress states within the admissible loading space. A minimax optimization technique is used to maximize the lowest natural frequency of a simply supported rectangular plate where the thickness distribution is the design variable and normal and shear initial stress states are considered. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
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Josef Habtínek 《Engineering Fracture Mechanics》1976,8(4):677-678
Uniaxial, biaxial and triaxial limit stress states in static and fatigue loading have been determined using triaxial models made from Cr-V and low-C steels. On triazial models from low-C steel the mechanism of fatigue failure in uni-, bi-, and triaxial loading was also studied. 相似文献
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《International Journal of Fatigue》2006,28(5-6):564-575
A cylindrical stiffener on a plate and a tube through a hollowed plate, both circularly welded, were tested under uniaxial fatigue loading. Their fatigue cracking behaviour was seen to be really complex due to the fact that crack initiation sites changed their position as the number of cycles to failure increased. To investigate this anomalous behaviour, an accurate numerical investigation was carried out to study the distribution of both local and structural linear elastic stresses along the weld toe circumferences. The numerical results proved that the weld beads were subjected to complex stress states, even though the applied nominal load was uniaxial. By the light of this evidence, the fatigue behaviour of the investigated welded joints was then re-interpreted from a multiaxial fatigue point of view by applying the Modified Wöhler Curve Method in terms of hot-spot stresses. The proposed approach was seen to be successful allowing us to estimate both crack initiation sites and fatigue lifetime with a high precision level. This fact is very interesting because it strongly supports the idea that our method can be used to assess real welded components subjected to multiaxial fatigue loading by simply post-processing linear-elastic finite-element results. 相似文献
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In this paper the problem of formulation of failure criteria in an asymmetrical cycle of fatigue in uniaxial stress state and thermal fatigue in biaxial stress states is presented.Published inProblemy Prochnosti, Nos. 1–2, pp. 103–108, January–February, 1995. 相似文献
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压电陶瓷元件因疲劳破坏而失效是造成高频发射换能器损坏的重要原因之一。以一款高频换能器为例分析了换能器功率疲劳现象和压电陶瓷功率疲劳机理;针对高频换能器水中阻抗与空气中阻抗比较接近的特点,设计了空气中大功率发射以加速复现功率疲劳的实验方法,制作了实验样机;实验较好地复现了电导值下降、发送电压响应下降的功率疲劳故障现象,验证了发射功率是换能器功率疲劳的主要因素。当发射功率较大时,散热环境是诱发功率疲劳的重要因素。为避免换能器产生功率疲劳,必须重视发射功率、工作环境和散热情况;发射功率越大对工作环境散热要求越高。 相似文献
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《International Journal of Fatigue》1987,9(1):51-55
An experimental technique is proposed for the estimation of crack length as well as crack closure/opening stress during fatigue crack growth. A specially designed, single cantilever, crack opening displacement gauge is used to monitor these variables during fatigue crack propagation testing. The technique was experimentally validated through electronfractography. 相似文献
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Andrea Carpinteri Andrea Spagnoli Sabrina Vantadori 《International Journal of Fatigue》2009,31(1):188-196
Many engineering structures experience multiaxial fatigue states of stress–strain in the vicinity of welded joints. Fatigue assessment of welded joints under proportional (in-phase) cyclic loading can be performed by using conventional hypotheses (e.g., see the von Mises criterion or the Tresca criterion) on the basis of local approaches. On the contrary, the fatigue life predictions of welded joints under non-proportional (out-of-phase) cyclic loading are generally poor if these conventional hypotheses are used. In the present paper, the critical plane-based multiaxial fatigue criterion proposed by Carpinteri and Spagnoli for smooth and notched structural components is extended to the fatigue assessment of welded joints under in- and out-of-phase loadings. The applicability of this criterion, expressed in terms of nominal stresses, to the fatigue life prediction of welded specimens is investigated by using experimental data available in the literature. 相似文献
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This paper presents a method of solving systems of simultaneous non-linear partial differential equations using the method of lines and the method of quasilinearization-superposition in combination. The advantages of the method over those methods more generally used are discussed and an example of the application of the method to the two-dimensional momentum and energy equations considering temperature-dependent and/or shear-rate dependent viscosity is given. 相似文献