Fatigue tests of asymmetric structural elements by axial loading

1995 ◽  
Vol 27 (5-6) ◽  
pp. 290-295 ◽  
Author(s):  
M. N. Regul'skii
Keyword(s):  
Axial Loading ◽  
Fatigue Tests ◽  
Structural Elements

Improving the accuracy of fatigue tests with axial loading

1978 ◽  
Vol 10 (9) ◽  
pp. 1110-1112
Author(s):  
�. Ya. Filatov ◽  
V. �. Pavlovskii ◽  
V. N. Belokurov
Keyword(s):  
Axial Loading ◽  
Fatigue Tests

Fatigue Behaviour of DLC Coated Al 7075-T6 Alloy in an Aggressive Mixture

2014 ◽  
Vol 627 ◽  
pp. 81-84 ◽  
Author(s):  
Sergio Baragetti ◽  
Riccardo Gerosa ◽  
Francesco Villa
Keyword(s):  
High Performance ◽  
Contact Fatigue ◽  
Fatigue Behaviour ◽  
Fatigue Tests ◽  
Structural Elements ◽  
Pvd Coatings ◽  
Bending Fatigue ◽  
Al 7075 ◽  
Rotating Bending Fatigue ◽  
Rotating Bending

7075-T6 aluminium alloy is commonly adopted in high performance structures and components. Its fatigue behaviour is however dramatically worsened by exposure to aggressive environments. The deposition of PVD coatings, which are commonly adopted to increase the surface properties of structural elements in terms of hardness, contact fatigue and wear resistance, could be beneficial also for the fatigue behaviour of a 7075-T6 substrate in an aggressive environment. In the present work, Diamond Like Carbon (DLC) PVD coated 7075-T6 specimens immersed in methanol have been analysed, by means of step-loading rotating bending fatigue tests (R = -1) at 2·105 cycles. Coated specimens were tested in laboratory air for comparison, and uncoated polished samples were studied in both the environments to obtain reference values. SEM micrographs of the fracture surfaces were taken to investigate the effects of the corrosive environment on the failure mechanism.

Design Curves for High-Cycle Fatigue Loaded Structural Elements

2013 ◽  
Vol 752 ◽  
pp. 135-144 ◽  
Author(s):  
Zsuzsanna Koncsik ◽  
János Lukács
Keyword(s):  
High Cycle Fatigue ◽  
Empirical Method ◽  
Fatigue Tests ◽  
Structural Elements ◽  
Cycle Fatigue ◽  
Structural Element ◽  
Fatigue Design ◽  
Structural Details ◽  
Important Design

Frequently, the cause of the failure of different structures or structural elements is the cyclic loading. Both fatigue design curves and methods for determination of these curves can be found in the literature. Even so, there are structural details whereabouts executing of examinations is necessary. The aims of the study are as follows: to give a short summary of important design curves can be found in different standards or specifications; and to demonstrate of own high cycle fatigue tests on a soldered structural element and the comparing of our results and the results of an empirical method.

scholarly journals Interior crack initiation during the very-high-cycle fatigue of railway wheel steel under axial loading and rolling contact loading

2021 ◽  
Author(s):  
Xiao-Long Liu ◽  
Pengcheng Gao ◽  
Si Wu ◽  
Guanzhen Zhang ◽  
Tao Cong
Keyword(s):  
Crack Initiation ◽  
High Cycle Fatigue ◽  
Axial Loading ◽  
Fatigue Tests ◽  
Rolling Contact ◽  
Wheel Steel ◽  
Contact Loading ◽  
Very High Cycle Fatigue ◽  
Very High ◽  
Railway Wheel Steel

In this paper, a comparative study of the very-high-cycle fatigue (VHCF) behavior of railway wheel steel under axial loading and rolling contact loading was conducted. Fatigue tests were performed with an ultrasonic fatigue test machine under axial loading, and the fracture surfaces from the fatigue tests and shattered rims taken from the failed railway wheels were observed. The wheel steel under axial loading presents a VHCF behavior with Mode I crack, and that under rolling contact loading is a VHCF behavior with mix Mode II-III crack. For the VHCF behavior with Mode I crack ,surface and interior crack initiation occurred with equal probability at both low and high stress levels and produced a dual linear S-N curve since the value of fatigue limits for the surface and interior crack initiation are close. For the VHCF behavior with mix Mode II-III crack, cracks were initiated from the interior Al O inclusion and the fatigue life was beyond 10 cycles. Fatigue bands were observed on the fracture surface under rolling contact loading. The ferrite nanograins formed due to the stress state of shear plastic strain with a large compressive stress. The formed nanograins were softer than the matrix caused by the redistribution of the carbon.

scholarly journals Fatigue Resistance Models of Structural for Risk Based Inspection

2020 ◽  
Vol 6 (2) ◽  
pp. 375-383
Author(s):  
Sergei Belodedenko ◽  
V. Hanush ◽  
A. Baglay ◽  
О. Hrechanyі
Keyword(s):  
Fatigue Resistance ◽  
Influence Factors ◽  
High Strength ◽  
Technical Condition ◽  
Damage Function ◽  
Fatigue Tests ◽  
Structural Elements ◽  
Model Combining ◽  
Safety Margins ◽  
Complex Indicators

The current stage of civil engineering is characterized by special attention to the safety of structures with a long service life. Such objects were designed several decades ago and their safe operation was ensured by significant safety margins. Now this approach to safety has been replaced by the concept of acceptable risk. It forms the basis of a risk based inspection (RBI) maintenance strategy. The transition from preventive maintenance strategies to a technical condition maintenance is substantiated. Complex indicators of technical condition, suitable for RBI- maintenance, are considered. The methodology of the resource safety index (RSI) is proposed. The latter is used as an indicator of risk. Special models of fatigue resistance is required for its control. The purpose of this paper is to build fatigue models for critical structural elements that are serviced according to the RBI concept. Instead of the traditional S-N curve, the lifetime general equation (first model) be used, where by the arguments are the main influence factors. Along with this, a modified ε - N equation is proposed for deformation criteria. The novelty of this equation is that it uses the rate of S-N- curve (slope) obtained in the first model with high cycle fatigue. The second model, combining the results of fatigue tests, is the equation for the dispersion of durability. The third model is the accumulated damage function under overloads. The efficiency of the RSI method is demonstrated by the example of the reliability assessment of the high strength bolts. Thanks to RSI method forecasting, during RBI-maintenance, parts can be used 3-5 times longer than with traditional methods.

Fatigue Capacity of Load Carrying Fillet-Welded Connections Subjected to Axial and Shear Loading

2009 ◽  
Vol 131 (4) ◽  
Author(s):  
Inge Lotsberg
Keyword(s):  
Axial Loading ◽  
Steel Structures ◽  
Fatigue Tests ◽  
Shear Loading ◽  
Fillet Welds ◽  
Strength Analysis ◽  
Load Carrying ◽  
Eurocode 3 ◽  
The Status ◽  
Current Design

The status on current design recommendations concerning the fatigue capacity of load carrying fillet welds was presented by Maddox (Maddox, S., 2006, “Status Review on Fatigue Performance of Fillet Welds,” Proceedings of the OMAE Conference, Hamburg, Germany, Jun., Paper No. OMAE2006-92314) based on a literature survey. In order to examine the validity of the recommendations and to supplement the fatigue test database, a test matrix with 33 specimens was developed. This included 8 simple fillet-welded cruciform joints that were subjected to axial loading and 25 fillet-welded tubular specimens that were subjected to axial load and/or torsion for simulation of a combined stress condition in the fillet weld. The data obtained from these fatigue tests are presented in this paper. The test data are also compared with design guidance from IIW (1996, Fatigue Design of Welded Joints and Components: Recommendations of IIW Joint Working Group XIII-XV, A. Hobbacher, ed., Abington Publishing, Cambridge), Eurocode 3 (1993, Eurocode 3: Design of Steel Structures—Part 1–1: General Rules and Rules for Buildings), and DNV-RP-C203 (DNV, 2005, DNV-RP-C203, Fatigue Strength Analysis of Offshore Steel Structures).

scholarly journals THE CRASH ENERGY ABSORPTION OF THE VEHICLES FRONT STRUCTURES

Transport ◽  
2003 ◽  
Vol 18 (2) ◽  
pp. 97-101 ◽  
Author(s):  
Paulius Griškevičius ◽  
Antanas Žiliukas
Keyword(s):  
Mechanical Characteristics ◽  
Axial Loading ◽  
Computer Code ◽  
Experimental Investigations ◽  
Fe Model ◽  
Structural Elements ◽  
Crash Analysis ◽  
Absorbed Energy ◽  
Frontal Crash ◽  
Energy Absorbing

During the frontal crash the longerons absorb most energy of all vehicles construction elements. In order to analyse the energy absorbing capabilities of longerons under axial compression loading and to evaluate the influence of longerons geometrical characteristics and materials degradation on the vehicles safety experimental investigations and numerical calculations were performed. To assess the crashworthiness of longerons the main objective was to study the behaviour of thin-walled structural elements under axial loading conditions using the Finite Element (FE) model. The numerical FE models were created using the computer code LS-DYNA. Two models of longerons were investigated with different sections shape and for each of them materials with the four different mechanical characteristics were applied. Validation of created FE model was performed according to the experimental investigation and the results were obtained of validated FE models of vehicles crash analysis [1]. The results of analyses show that the value of absorbed energy by the longerons of new vehides exceeds the value of the oldest cars. The degradation of structures in the old cars has the significant influence on the absorbed energy.

Fatigue Capacity of Fillet Welded Connections Subjected to Axial and Shear Loading

2006 ◽  
Author(s):  
Inge Lotsberg
Keyword(s):  
Test Data ◽  
Stress Condition ◽  
Axial Loading ◽  
Fatigue Tests ◽  
Shear Loading ◽  
Cruciform Joints ◽  
The Status ◽  
Current Design ◽  
Tubular Specimens ◽  
Design Guidance

The status on current design recommendations concerning the fatigue capacity of fillet welds was presented by Maddox (2002), based on a literature survey. In order to examine the validity of the recommendations and to supplement the fatigue test data base, a test matrix with 33 specimens was developed. This included 8 simple fillet welded cruciform joints that were subjected to axial loading and 25 fillet welded tubular specimens that were subjected to axial load and/or torsion for simulation of a combined stress condition in the fillet weld. The data obtained from these fatigue tests are presented in this paper. The test data are also compared with design guidance from IIW (1996), Eurocode 3 (1993) and DNV-RP-C203 (2005).

scholarly journals Algorithm for determination of S-N curves of the structural elements subjected to cyclic loading

2018 ◽  
Vol 16 (1) ◽  
pp. 81-91 ◽  
Author(s):  
Nenad Stojkovic ◽  
Dragoslav Stojic ◽  
Srdjan Zivkovic ◽  
Gordana Toplicic-Curcic
Keyword(s):  
Experimental Data ◽  
Fatigue Life ◽  
Cyclic Loading ◽  
Fatigue Tests ◽  
Likelihood Method ◽  
Model Parameters ◽  
Structural Elements ◽  
Number Of Cycles ◽  
Predetermined Number

Fatigue life prediction of structural elements subjected to cyclic loading is usually performed using S-N curves, obtained from the experimental data from fatigue tests. However, in some cases the samples do not exhibit failure, due to reaching the predetermined number of cycles, failure of a non-relevant segment or terminating the test because of some other reason. These samples are usually referred to as runouts, and the data obtained from them could be used for determination of S-N curves as well. In this paper, the algorithm based on Maximum Likelihood method is proposed for the determination of S-N curves from experimental data that contain runouts. Following the algorithm, a MATLAB code was written and the verification was performed using the experimental data from the literature. The results showed that it could be successfully used for taking into account the runouts in the process of determination of S-N model parameters. It was concluded that the inclusion of runouts could significantly influence the predicted fatigue life, especially at the lower stress levels.

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