New models for depicting corrosion fatigue behaviour and calendar life of metallic structural component

2016 ◽  
Vol 231 (2) ◽  
pp. 207-222 ◽  
Author(s):  
Yu Fu ◽  
Junjiang Xiong ◽  
R Ajit Shenoi
Keyword(s):  
Corrosion Fatigue ◽  
Structural Component ◽  
Damage Model ◽  
Fatigue Behaviour ◽  
Fatigue Tests ◽  
Surface Model ◽  
Proposed Model ◽  
New Models ◽  
Best Fitting ◽  
New Formula

New [Formula: see text] surface model is proposed for depicting corrosion fatigue behaviour and novel formulae are derived to estimate the parameters of proposed model by best fitting from a minimal experimental dataset of corrosion fatigue tests. From the Palmgren–Miner rule, a cumulative damage model for the alternation between corrosion and fatigue is developed to evaluate calendar life of metallic structural component. Corrosion tests are conducted on unnotched and notched specimens from LD10CS aluminium alloy and 15CrMnMoVA alloy steel in artificial corrosion environments. Fatigue tests are also performed on corroded specimens subjected to constant amplitude loading and the interaction mechanisms between corrosion and fatigue are deduced from fractographic studies. The applicability of the new models has been shown for experimental datasets for depicting corrosion fatigue behaviour and for evaluating calendar life of motor brace rod in helicopter.

scholarly journals Experimental and Analytical Study on Residual Stiffness/Strength of CFRP Tendons under Cyclic Loading

Materials ◽  
2020 ◽  
Vol 13 (24) ◽  
pp. 5653
Author(s):  
Chao Wang ◽  
Jiwen Zhang
Keyword(s):  
Residual Strength ◽  
Analytical Study ◽  
Damage Model ◽  
Fatigue Loading ◽  
Fatigue Tests ◽  
Fiber Reinforced Polymer ◽  
Carbon Fiber Reinforced Polymer ◽  
Reinforced Polymer ◽  
Proposed Model ◽  
Residual Stiffness

Based on tension–tension fatigue tests, this paper investigated the mechanical property degradation of carbon fiber reinforced polymer (CFRP) tendons from a macroscopic perspective. According to the degradation regularity, this paper proposed a normalized phenomenological fatigue model based on the residual stiffness/strength of CFRP tendons during the fatigue loading process. In this paper, the residual stiffness of CFRP tendons were tested at five stress ranges, while the residual strength was tested at four stress ranges. In order to validate the reliability and applicability of proposed fatigue damage model, the predictions of proposed model and cited models from the literature are discussed and compared. Furthermore, experimental results from literatures were adopted to verify the accuracy of the proposed model. The results showed that the proposed model is applicable to predict both residual stiffness and residual strength throughout fatigue life cycle and has a better accuracy than models from the literature. Moreover, the three-stage degradation can be observed from the degradation processes of stiffness and strength at each stress level.

A Three Dimensional Graphical Aid for Fatigue Data Analysis

2011 ◽  
Vol 488-489 ◽  
pp. 755-758 ◽  
Author(s):  
Bruno Atzori ◽  
Giovanni Meneghetti ◽  
Mauro Ricotta
Keyword(s):  
Experimental Data ◽  
Data Analysis ◽  
Three Dimensional ◽  
Strain Curve ◽  
Fatigue Behaviour ◽  
Fatigue Tests ◽  
Compatibility Conditions ◽  
Stress Strain ◽  
Fatigue Data ◽  
Best Fitting

The fatigue behaviour of materials is usually synthesised in terms of stress-life (S-N) curve or in terms of strain-life (e-N) curve, the latter being described by the so-called Manson-Coffin equation. It is known that the assumption of equality of the plastic and elastic components between the Manson-Coffin and the stabilised stress-strain curves leads to the so-called compatibility conditions which connect the equations theoretically. The material constants of the Manson-Coffin and of the stabilised stress-strain curve are commonly determined by best fitting separately the experimental data obtained from strain-controlled fatigue tests. As a consequence the compatibility conditions may not be fulfilled. In this paper a method for fatigue data analysis that ensures the compatibility conditions is proposed and validated against experimental data.

Influence of Load Signal Form and Variable Amplitude Loading on the Corrosion Fatigue Behaviour of Aluminium Alloys

2014 ◽  
Vol 891-892 ◽  
pp. 217-223 ◽  
Author(s):  
Kathrin Bauer-Trossmann ◽  
Liu Hao Yu ◽  
Tobias Melz ◽  
Matthias Oechsner ◽  
Heinz Kaufmann
Keyword(s):  
Corrosion Fatigue ◽  
Aluminium Alloys ◽  
Magnesium Content ◽  
Fatigue Behaviour ◽  
Thermal Ageing ◽  
Fatigue Tests ◽  
Electrochemical Characteristics ◽  
Variable Amplitude Loading ◽  
Variable Amplitude ◽  
The Impact

Aluminium alloys are used for a large variety of safety relevant applications for example in the automotive and aviation industries. With the introduction of high strength but possibly less corrosion resistant alloys it is essential to determine if an enhanced sensitisation against corrosion comes into effect under simultaneous mechanical and corrosive loading. Within this work corrosion fatigue tests under constant and variable amplitude loading were carried out on aluminium alloys established for chassis applications such as EN AW-5018 with slightly elevated magnesium content (AlMg3.5Mn), EN AW-6082-T6, EN AW-6110A-T6 and EN AC‑42100-T6 as well as alloys sensitised to corrosion. Sensitisation was obtained by a borderline (17 h at 130 °C) and an excessive (500 h at 130 °C) thermal ageing treatment and elevated copper contents for the forged and cast alloys. Aforementioned alloys and material conditions were assessed concerning the impact of mechanical loading conditions such as load signal type (sinusoidal and square-wave signal), strain rate and load spectra on the damaging process and on corrosion fatigue life. Fatigue tests were complemented by simultaneous determination of electrochemical characteristics as well as the type of corrosion by metallographic investigations.

scholarly journals Limited Stress Surface Model for Bending and Torsion Fatigue Loading with the Mean Load Value

Materials ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 7023
Author(s):  
Roland Pawliczek ◽  
Dariusz Rozumek
Keyword(s):  
Stress Amplitude ◽  
Fatigue Loading ◽  
Mean Value ◽  
Fatigue Tests ◽  
Surface Model ◽  
Cycle Asymmetry ◽  
Proposed Model ◽  
Stress Surface ◽  
Alloy Steels ◽  
The Mean

In this study, a linear model of the transformation of the stress amplitude due to the mean value was used. The coefficient of the material sensitivity to cycle asymmetry with consideration of the dependence of this coefficient on the number of fatigue loading cycles is also used. A three-parameter surface model of limited stresses is proposed in this paper. The model is verified using the results of fatigue tests for cyclic bending and torsion under mean loads. The tests are performed for two types of alloy steels—S355J0 and S355J2G1W. Comparison of the allowable stress amplitudes obtained experimentally with those predicted using the proposed model shows errors of no more than 18%, with the area of the surface with the largest error being relatively small.

scholarly journals Fatigue and Corrosion Fatigue Behaviour of Brazed Stainless Steel Joints AISI 304L/BAu-4 in Synthetic Exhaust Gas Condensate

Materials ◽  
2019 ◽  
Vol 12 (7) ◽  
pp. 1040 ◽  
Author(s):  
Anke Schmiedt-Kalenborn ◽  
Lars Lingnau ◽  
Matthias Manka ◽  
Wolfgang Tillmann ◽  
Frank Walther
Keyword(s):  
Stainless Steel ◽  
Corrosion Fatigue ◽  
Cyclic Deformation ◽  
Fatigue Behaviour ◽  
Fatigue Tests ◽  
Exhaust Gas ◽  
Aisi 304L ◽  
Brazed Joints ◽  
Corrosive Environments ◽  
Steel Joints

As brazed stainless steel components in service often have to withstand cyclic loads in corrosive environments, the corrosion fatigue properties of brazed joints have to be characterised. Application-relevant corrosion fatigue tests in corrosive media are extremely rare for brazed joints and cyclic deformation curves are barely investigated. In this study, fatigue tests of brazed AISI 304L/BAu-4 joints were performed in air and synthetic exhaust gas condensate K2.2 according to VDA 230-214. The fatigue behaviour of the brazed joints was compared to properties of the austenitic base material. Strain, electrical, magnetic, temperature and electrochemical measurement techniques were applied within fatigue and corrosion fatigue tests to characterise the cyclic deformation and damage behaviour of the brazed joints. It was found that the fatigue strength of 397 MPa at 2 × 106 cycles was reduced down to 51% due to the superimposed corrosive loading. Divergent microstructure-related damage mechanisms were identified for corrosion fatigue loadings and fatigue loadings of specimens in the as-received and pre-corroded conditions. The investigations demonstrate the important role of corrosive environments for the mechanical performance of brazed stainless steel joints.

Static and Fatigue Characterization of Sandwich Panels

2006 ◽  
Vol 518 ◽  
pp. 555-0 ◽  
Author(s):  
Ahmed Abbadi ◽  
Z. Azari ◽  
Salim Belouettar ◽  
J. Gilgert ◽  
G. Pluvinage
Keyword(s):  
Damage Model ◽  
Sandwich Panels ◽  
Fatigue Behaviour ◽  
Fatigue Tests ◽  
Stiffness Degradation ◽  
Static Tests ◽  
Damage Models ◽  
Load Carrying ◽  
Sandwich Type

Problems for load carrying elements reside mainly in buckling, embrittlement and corrosion. These problems can be mainly solved by introduction of composite materials of a sandwich type. These materials ally lightness, rigidity and resistance to the corrosion. For the design of a large number of applications, static and cyclic properties are necessary. In this paper, first static and fatigue tests on four points bending of four types sandwich panels have been performed. Load/displacement and S-N fatigue curves are presented and analysed. Fatigue failure and damage modes are observed with an electronic microscope and are discussed. Numerical simulation applied to the static tests is compared to the experimental results. The second is to address such fatigue behaviour by using a damage model and check it by experimentation. This fatigue damage model is based on stiffness degradation, which is used as a damage indicator. Four non-linear cumulative damage models derived from the chosen stiffness degradation equation are examined with assumption of linear Miner’s damage summation. Predicted results are compared with available experimental data.

Fatigue Behaviour of Friction Stir Welded Steel Joints

2014 ◽  
Vol 891-892 ◽  
pp. 1488-1493 ◽  
Author(s):  
José Azevedo ◽  
Virgínia Infante ◽  
Luisa Quintino ◽  
Jorge dos Santos
Keyword(s):  
Base Material ◽  
Welding Process ◽  
Steel Structures ◽  
Fatigue Behaviour ◽  
Fatigue Tests ◽  
Fatigue Properties ◽  
Welded Steel ◽  
Shipbuilding Industry ◽  
Friction Stir ◽  
Steel Joints

The development and application of friction stir welding (FSW) technology in steel structures in the shipbuilding industry provide an effective tool of achieving superior joint integrity especially where reliability and damage tolerance are of major concerns. Since the shipbuilding components are inevitably subjected to dynamic or cyclic stresses in services, the fatigue properties of the friction stir welded joints must be properly evaluated to ensure the safety and longevity. This research intends to fulfill a clear knowledge gap that exists nowadays and, as such, it is dedicated to the study of welded steel shipbuilding joints in GL-A36 steel, with 4 mm thick. The fatigue resistance of base material and four plates in as-welded condition (using several different parameters, tools and pre-welding conditions) were investigated. The joints culminate globally with defect-free welds, from which tensile, microhardness, and fatigue analyses were performed. The fatigue tests were carried out with a constant amplitude loading, a stress ratio of R=0.1 and frequency between 100 and 120 Hz. The experimental results show the quality of the welding process applied to steel GL-A36 which is reflected in the mechanical properties of joints tested.

A Reliability-Based Approach to Assess Fatigue Behaviour Based on Small Incomplete Data Sets

2008 ◽  
Vol 44-46 ◽  
pp. 871-878 ◽  
Author(s):  
Chu Yang Luo ◽  
Jun Jiang Xiong ◽  
R.A. Shenoi
Keyword(s):  
Incomplete Data ◽  
Standard Procedure ◽  
Fatigue Behaviour ◽  
Fatigue Tests ◽  
Small Sample ◽  
Data Sets ◽  
Safe Life ◽  
A New Technique ◽  
And Performance

This paper outlines a new technique to address the paucity of data in determining fatigue life and performance based on reliability concepts. Two new randomized models are presented for estimating the safe life and pS-N curve, by using the standard procedure for statistical analysis and dealing with small sample numbers of incomplete data. The confidence level formulations for the safe and p-S-N curve are also given. The concepts are then applied for the determination of the safe life and p-S-N curve. Two sets of fatigue tests for the safe life and p-S-N curve are conducted to validate the presented method, demonstrating the practical use of the proposed technique.

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