Generalization of Spectral Methods for High-Cycle Fatigue Analysis to Accommodate Non-Stationary Random Processes

2019 ◽  
Author(s):  
Mohamed Khalil ◽  
Roland Wüchner ◽  
Kai-Uwe Bletzinger
Keyword(s):  
Sensitivity Analysis ◽  
Fatigue Life ◽  
Spectral Methods ◽  
High Cycle Fatigue ◽  
Random Processes ◽  
Stationary Processes ◽  
Cycle Fatigue ◽  
Material Fatigue ◽  
Frequency Domains ◽  
Stationary Random Processes

Abstract Estimation of material fatigue life is an essential task in many engineering fields. When non-proportional loads are applied, the methodology to estimate fatigue life grows in complexity. Many methods have been proposed to solve this problem both in time and frequency domains. The former tends to give more accurate results, while the latter seems to be more computationally favorable. Until now, the focus of frequency-based methods has been limited to signals assumed to follow a stationary statistic process. This work proposes a generalization to the existing methods to accommodate non-stationary processes as well. A sensitivity analysis is conducted on the influence of the formulation’s hyper-parameters, followed by a numerical investigation on different signals and various materials to assert the robustness of the method.

High-cycle fatigue tests of pretensioned concrete beams

PCI Journal ◽  
2022 ◽  
Vol 67 (1) ◽  
Author(s):  
Jörn Remitz ◽  
Martin Empelmann
Keyword(s):  
Fatigue Life ◽  
High Cycle Fatigue ◽  
Concrete Beams ◽  
Fatigue Behavior ◽  
Fatigue Tests ◽  
Design Methods ◽  
Test Results ◽  
Cycle Fatigue ◽  
Pretensioned Concrete ◽  
Current Design

Pretensioned concrete beams are widely used as bridge girders for simply supported bridges. Understanding the fatigue behavior of such beams is very important for design and construction to prevent fatigue failure. The fatigue behavior of pretensioned concrete beams is mainly influenced by the fatigue of the prestressing strands. The evaluation of previous test results from the literature indicated a reduced fatigue life in the long-life region compared with current design methods and specifications. Therefore, nine additional high-cycle fatigue tests were conducted on pretensioned concrete beams with strand stress ranges of about 100 MPa (14.5 ksi). The test results confirmed that current design methods and specifications overestimate the fatigue life of embedded strands in pretensioned concrete beams.

High Cycle Fatigue Damage Evaluation of Steel Pipelines Based on Microhardness Changes During Cyclic Loads: Part II

2018 ◽  
Author(s):  
Geovana Drumond ◽  
Bianca Pinheiro ◽  
Ilson Pasqualino ◽  
Francine Roudet ◽  
Didier Chicot
Keyword(s):  
Fatigue Life ◽  
Fatigue Damage ◽  
High Cycle Fatigue ◽  
Steel Structures ◽  
New Method ◽  
Microplastic Deformation ◽  
Surface Phenomenon ◽  
Cyclic Loads ◽  
Cycle Fatigue ◽  
Indentation Tests

The hardness of a material shows its ability to resist to microplastic deformation caused by indentation or penetration and is closely related to the plastic slip capacity of the material. Therefore, it could be significant to study the resistance to microplastic deformations based on microhardness changes on the surface, and the associated accumulation of fatigue damage. The present work is part of a research study being carried out with the aim of proposing a new method based on microstructural changes, represented by a fatigue damage indicator, to predict fatigue life of steel structures submitted to cyclic loads, before macroscopic cracking. Here, Berkovich indentation tests were carried out in the samples previously submitted to high cycle fatigue (HCF) tests. It was observed that the major changes in the microhardness values occurred at the surface of the material below 3 μm of indentation depth, and around 20% of the fatigue life of the material, proving that microcracking is a surface phenomenon. So, the results obtained for the surface of the specimen and at the beginning of the fatigue life of the material will be considered in the proposal of a new method to estimate the fatigue life of metal structures.

Finite element prediction of high cycle fatigue life of aluminum alloys

1990 ◽  
Vol 21 (4) ◽  
pp. 1151-1159 ◽  
Author(s):  
William J. Baxter ◽  
Pei-Chung Wang
Keyword(s):  
Finite Element ◽  
Fatigue Life ◽  
Aluminum Alloys ◽  
High Cycle Fatigue ◽  
Cycle Fatigue ◽  
Finite Element Prediction

scholarly journals Analysis of Compressive Fatigue Failure of Recycled Aggregate Concrete

Materials ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4620
Author(s):  
Fan You ◽  
Surong Luo ◽  
Jianlan Zheng ◽  
Kaibin Lin
Keyword(s):  
Fatigue Life ◽  
Fatigue Failure ◽  
High Cycle Fatigue ◽  
Fatigue Behavior ◽  
Recycled Aggregate Concrete ◽  
Construction And Demolition Waste ◽  
Recycled Aggregate ◽  
Cycle Fatigue ◽  
Demolition Waste ◽  
Aggregate Concrete

Using recycled aggregate in concrete is effective in recycling construction and demolition waste. It is of critical significance to understand the fatigue properties of recycled aggregate concrete (RAC) to implement it safely in structures subjected to repeated or fatigue load. In this study, a series of fatigue tests was performed to investigate the compressive fatigue behavior of RAC. The performance of interfacial transition zones (ITZs) was analyzed by nanoindentation. Moreover, the influence of ITZs on the fatigue life of RAC was discussed. The results showed that the fatigue life of RAC obeyed the Weibull distribution, and the S-N-p equation could be obtained based on the fitting of Weibull parameters. In the high cycle fatigue zone (N≥104), the fatigue life of RAC was lower than that of natural aggregate concrete (NAC) under the same stress level. The fatigue deformation of RAC presented a three-stage deformation regularity, and the maximum deformation at the point of fatigue failure closely matched the monotonic stress-strain envelope. The multiple ITZs matched the weak areas of RAC, and the negative effect of ITZs on the fatigue life of RAC in the high cycle fatigue zone was found to be greater than that of NAC.

scholarly journals High Cycle Fatigue Appearance of 10wt% cr steel and Dissimilar Metal Weld

2021 ◽  
Vol 9 (VI) ◽  
pp. 2185-2202
Author(s):  
Hilal Ahmad Shah
Keyword(s):  
Fatigue Life ◽  
High Cycle Fatigue ◽  
Stress Amplitude ◽  
Cycle Fatigue ◽  
Crack Initiation And Propagation ◽  
R Ratio ◽  
Initiation And Propagation ◽  
Different Temperatures ◽  
Fracture Surface Analysis ◽  
Metal Weld

The present study deals with the high cycle fatigue (HCF) behavior of a ten wt% Cr steel at ambient also as high temperatures (300–853 K). S–N curves were created at unlike temperatures using an R-ratio of −1. Outcome of mean stress was established over and done with Haigh diagram at 853 K using different R-values. Fatigue life was found to decrease with upsurge in test temperature and stress amplitude. Fatigue life was attempted using Basquin equation. Detailed fracture surface analysis was performed to study the crack initiation and propagation modes towards empathetic the mechanisms of failure at different temperatures.

Structural Design and Analysis of Cylindrical Squirrel Cage to Meet Stiffness, Strength and High Cycle Fatigue Life for an Aero Engine

2017 ◽  
Author(s):  
Senthil Kumar Kandhaswamy Srinivasan ◽  
Nazar Periarowthar
Keyword(s):  
Fatigue Life ◽  
Structural Design ◽  
High Cycle Fatigue ◽  
Aircraft Engine ◽  
Squeeze Film ◽  
Cycle Fatigue ◽  
Squeeze Film Damper ◽  
Squirrel Cage ◽  
Fillet Radius ◽  
Goodman Diagram

Squeeze film dampers have traditionally been used in aircraft engine to overcome stability and vibration problems that are not adequately handled with conventional style bearings. One of the key design features in a squeeze film damper [1] configuration is the introduction of flexibility in the bearing support. The simplest means to provide the support flexibility in the squeeze film damper is through the use of squirrel cage [2]. This paper deals with structural design analysis of cylindrical squirrel cage of an aircraft engine. Design of the squirrel cage needs a balance between stiffness and strength requirements. To meet the strength, stiffness and fatigue life requirements, squirrel cage web dimensions and fillet radius are modified. The various configurations of the squirrel cage have been evaluated to arrive at the optimum design. Stress analysis of the bearing has been carried out for axial, radial unbalance loads. Stress distribution in the web region has been studied in detail. High cycle fatigue life margins are estimated using Goodman diagram. The squirrel cage web dimensions and fillet radius are modified to improve HCF life requirements. The operating stresses in the squirrel cage are reduced while meeting the stiffness and HCF life requirements of the component.

Prediction of the fatigue life of VT1-0 titanium in various structural states under very high cycle fatigue

2021 ◽  
Vol 11 (4) ◽  
pp. 422-426
Author(s):  
Dmitry Ledon ◽  
Mikhail Bannikov ◽  
Vladimir Oborin ◽  
Yuriy Bayandin ◽  
Oleg Naimark
Keyword(s):  
Fatigue Life ◽  
High Cycle Fatigue ◽  
Cycle Fatigue ◽  
Very High Cycle Fatigue ◽  
Very High
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