Multi-mode Model and Calculation Method for Fatigue Damage Development

2021 ◽  
pp. 157-170
Author(s):  
Ilia S. Nikitin ◽  
Nikolay G. Burago ◽  
Alexander D. Nikitin ◽  
Boris A. Stratula
Keyword(s):  
Fatigue Damage ◽  
Calculation Method ◽  
Damage Development ◽  
Multi Mode

Calculation method of dynamic loads spectrum and effects on fatigue damage of a full-scale carbody for high-speed trains

2019 ◽  
Vol 58 (7) ◽  
pp. 1037-1056 ◽  
Author(s):  
Yaohui Lu ◽  
Wei Bi ◽  
Xing Zhang ◽  
Jing Zeng ◽  
Tianli Chen ◽  
...  
Keyword(s):  
Fatigue Damage ◽  
Calculation Method ◽  
High Speed ◽  
Full Scale ◽  
Dynamic Loads ◽  
High Speed Trains

scholarly journals Fatigue Life Analysis of Aluminum Alloy Notched Specimens under Non-Gaussian Excitation based on Fatigue Damage Spectrum

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Kuanyu Chen ◽  
Guangwu Yang ◽  
Jianjun Zhang ◽  
Shoune Xiao ◽  
Yang Xu
Keyword(s):  
Aluminum Alloy ◽  
Fatigue Life ◽  
Fatigue Damage ◽  
Relative Error ◽  
Gaussian Distribution ◽  
Calculation Method ◽  
Shaking Table ◽  
Notched Specimens ◽  
Acceleration Method ◽  
Non Gaussian

In this study, a non-Gaussian excitation acceleration method is proposed, using aluminum alloy notched specimens as a research object and measured acceleration signal of a certain airborne bracket, during aircraft flight as input excitations, based on the fatigue damage spectrum (FDS) theory. The kurtosis and skewness of the input signal are calculated and the non-Gaussian characteristics and amplitude distribution are evaluated. Five task segments obey a non-Gaussian distribution, while one task segment obeys a Gaussian distribution. The fatigue damage spectrum calculation method of non-Gaussian excitation is derived. The appropriate FDS calculation method is selected for each task segment and the acceleration parameters are set to construct the acceleration power spectral density, which is equivalent to the pseudo-acceleration damage. A finite-element model is established, the notch stress concentration factor of the specimen is calculated, the large mass point method is used to simulate the shaking table excitation, and a random vibration analysis is carried out to calculate the accelerated fatigue life. The simulation results show that the relative error between the original cumulative damage and test original fatigue life is 15.7%. The shaking table test results show that the relative error of fatigue life before and after acceleration is less than 16.95%, and the relative error of test and simulation is 24.27%. The failure time of the specimen is accelerated from approximately 12 h to 1 h, the acceleration ratio reaches 12, and the average acceleration ideal factor is 1.125, which verifies the effectiveness of the acceleration method. It provides a reference for the compilation of the load spectrum and vibration endurance acceleration test of other airborne aircraft equipment.

Effect of Ply Constraint on Fatigue Damage Development in Composite Material Laminates

2009 ◽  
pp. 64-64-21 ◽  
Author(s):  
WW Stinchcomb ◽  
KL Reifsnider ◽  
P Yeung ◽  
J Masters
Keyword(s):  
Composite Material ◽  
Fatigue Damage ◽  
Damage Development

Fatigue Damage Evaluation in CFRP Woven Fabric Composites Through Dynamic Modulus Measurements

2004 ◽  
Author(s):  
Hideaki Kasano ◽  
Osamu Hasegawa ◽  
Chiaki Miyasaka
Keyword(s):  
Fatigue Damage ◽  
Material Properties ◽  
Elastic Moduli ◽  
Fatigue Loading ◽  
Damage Function ◽  
Fatigue Tests ◽  
Woven Fabric ◽  
Damage Development ◽  
Dynamic Elastic Moduli ◽  
Number Of Cycles

Advanced fiber reinforced composite materials offer substantial advantages over metallic materials for the structural applications subjected to fatigue loading. With the increasing use of these composites, it is required to understand their mechanical response to cyclic loading [1–4]. Our major concern in this work is to macroscopically evaluate the damage development in composites during fatigue loading. For this purpose, we examine what effect the fatigue damage may have on the material properties and how they can be related mathematically to each other. In general, as the damage initiates in composite materials and grows during cyclic loading, material properties such as modulus, residual strength and strain would vary and, in many cases, they may be significantly reduced because of the progressive accumulation of cracks. Therefore, the damage can be characterized by the change in material properties, which is expected to be available for non-destructive evaluation of the fatigue damage development in composites. Here, the tensiontension fatigue tests are firstly conducted on the plain woven fabric carbon fiber composites for different loading levels. In the fatigue tests, the dynamic elastic moduli are measured on real-time, which will decrease with an increasing number of cycles due to the degradation of stiffness. Then, the damage fimction presenting the damage development during fatigue loading is determined from the dynamic elastic moduli thus obtained, from which the damage function is formulated in terms of a number of cycles and an applied loading level. Finally, the damage function is shown to be applied for predicting the remaining fifetime of the CFRP composites subjected to two-stress level fatigue loading.

Fatigue damage development in Al2O3/Al composite

1994 ◽  
Vol 16 (3) ◽  
pp. 230-230
Author(s):  
X LIU ◽  
C BATHIAS
Keyword(s):  
Fatigue Damage ◽  
Damage Development ◽  
Al Composite

scholarly journals Assessment of fatigue damage development in power engineering steel by local strain analysis

2016 ◽  
Vol 52 (05) ◽  
pp. 269-277 ◽  
Author(s):  
D. KUKLA ◽  
Z. KOWALEWSKI ◽  
P. GRZYWNA ◽  
K. KUBIAK
Keyword(s):  
Fatigue Damage ◽  
Strain Analysis ◽  
Local Strain ◽  
Power Engineering ◽  
Damage Development ◽  
Engineering Steel

scholarly journals Fatigue Damage Characterization of Braided and Woven Fiber Reinforced Polymer Matrix Composites at Room and Elevated Temperatures

2021 ◽  
Author(s):  
John Montesano
Keyword(s):  
Elevated Temperature ◽  
Prediction Model ◽  
Fatigue Damage ◽  
Polymer Matrix ◽  
Elevated Temperatures ◽  
Polymer Matrix Composites ◽  
Stiffness Degradation ◽  
Woven Composites ◽  
Matrix Composites ◽  
Damage Development

The use of polymer matrix composites (PMC) for manufacturing primary load-bearing structural components has significantly increased in many industrial applications. Specifically in the aerospace industry, PMCs are also being considered for elevated temperature applications. Current aerospace-grade composite components subjected to fatigue loading are over-designed due to insufficient understanding of the material failure processes, and due to the lace of available generic fatigue prediction models. A comprehensive literature survey reveals that there are few fatigue studies conducted on woven and braided fabric reinforced PMC materials, and even fewer at elevated temperatures. It is therefore the objective of this study to characterize and subsequently model the elevated temperature fatigue behaviour of a triaxial braided PMC, and to investigate the elevated temperature of fatigue properties of two additional woven PMCs. An extensive experimental program is conducted using a unique test protocol on the braided and woven composites, which consists of static and fatigue testing at various test temperatures. The development of mechanically-induced damage is monitored using a combination of non-destructive techniques which included infrared thermography, fiber optic sensors and edge replication. The observed microscopic damage development is quantified and correlated to the exhibited macroscopic material behaviour at all test temperatures. The fiber-dominated PMC materials considered in this study did not exhibit notable time or temperature-dependent static properties. However, fatigue tests reveal that the local damage development is in fact notably influenced by temperature. The elevated temperature environment increases the toughness of the thermosetting polymers, which results in consistently slower fatigue crack propagation rates for the respective composite materials. This has a direct impact on the stiffness degradation rate and the fatigue lives for the braided and woven composites under investigation. The developed analytical fatigue damage prediction model, which is based on actual observed damage mechanisms, accurately predicted the development of damage and corresponding stiffness degradation for the braided PMC, for all test temperatures. An excellent correlation was found between the experimental the predicted results to within a 2% accuracy. The prediction model adequately captured the local temperature-induced phenomenon exhibited by the braided PMC material. The results presented in this study are novel for a braided composite material subjected to elevated temperature fatigue.

scholarly journals Pitting process visualization

2010 ◽  
Vol 58 (5) ◽  
pp. 57-66
Author(s):  
Michal Černý ◽  
Josef Filípek ◽  
Roman Požár
Keyword(s):  
Fatigue Damage ◽  
Development Process ◽  
Gear Tooth ◽  
Plastic State ◽  
Time Domain Simulation ◽  
Damage Development ◽  
Process Visualization ◽  
Micro Cracks ◽  
Tooth Sample ◽  
Material Volume

The paper describes time-domain simulation of gear pitting damage using animation program. Key frames have been used to create illusion of motion. The animation uses experimental results of high-cycle fatigue of material. The fatigue damage occurs in the nominal creep area on the side of the gear tooth sample loaded with variable-positioned Hertz pressure. By applying the force, the pressure cumulates between two convex surfaces. This phenomenon results in material damage under of curved surfaces in contact. Moreover, further damage has been registered on the surface. This is due to exceeding the elastic-plastic state limit and development of „tabs“. The tabs serve as origin of surface micro cracks powered by shear stress and enclosed grease pressure as well. This deformation and extreme pressures of Pascal law contribute to elongation and growth of the surface micro crack. Non-homogenous parts of material volume support the initialization/development of the micro cracks as well. Resulting visualization of the tooth-side fatigue damage provides clear and easy-to-understand description of the damage development process right from the micro crack initialization to the final fragmentation due to pitting degradation.

The Effect on Large Container Ships’ Fatigue due to Springing Loads Coupling Horizontal and Torsional Vibrations

2018 ◽  
Author(s):  
Hui Li ◽  
Huifen Xu ◽  
Huilong Ren ◽  
Xiaoxi Shen ◽  
Yubo Wang
Keyword(s):  
Fatigue Damage ◽  
Torsional Vibration ◽  
Calculation Method ◽  
Wave Loads ◽  
Analysis Method ◽  
Element Analysis ◽  
Hull Structure ◽  
Torsional Loads ◽  
Large Container ◽  
Simplified Calculation

The issue of hydroelasticity caused by hull vibration has become an unavoidable problem in the design and verification of large ships. Driven by environmental protection and economical efficiency, the size of ships are increasingly larger, and the resulting springing and whipping response and their effects on fatigue damage has been paid more and more attention especially for ultra large container ships (ULCS). Many classification societies typically check fatigue damage caused by vertical bending when considering springing, while it needs to be emphasized that large container ships can suffer severe torsional loads compared to other large ships due to wide breath and big hatch openings. In the existing stress calculation method, the finite element analysis method obviously has a high calculation accuracy. However, there are so much work to do with FEM model established, and partially refined, operated at all sea states etc., which not only requires much time, but also higher computing equipment. Therefore, in this paper, a simplified calculation method of fatigue damage considering the effect of bending and torsion is proposed, and a 21000TEU will be calculated by this method. The wave loads on the hull structure will be estimated based on the 3D linear hydroelastic theory coupling horizontal and torsional vibration, and the stress caused by bending and torsion will be obtained respectively. Finally, the fatigue damage is calculated by spectral analysis method considering high frequency springing loads. Then the effect on large container ships’ fatigue due to bending and torsional vibration is discussed.

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