Some Fatigue Tests on Aluminium-alloy and Mild-steel Sheet, with and without Drilled Holes

1951 ◽  
Vol 165 (1) ◽  
pp. 125-140 ◽  
Author(s):  
C. E. Phillips ◽  
A. J. Fenner
Keyword(s):  
Fatigue Strength ◽  
Mild Steel ◽  
Aluminium Alloy ◽  
Marked Reduction ◽  
Steel Sheet ◽  
Fatigue Tests ◽  
Slight Reduction ◽  
Maximum Width ◽  
Steel Panels ◽  
Comparison Of The Results

This paper describes fatigue tests, under pulsating direct stress, of aluminium-alloy and mild-steel panels, with and without central holes, approximately 0·1 inch in thickness and up to 12 inches in maximum width. Comparison of the results of tests on panels of similar shapes but of different sizes shows that larger panels are relatively weaker. The influence on the fatigue strength of varying the size of a drilled hole in a wide panel has been explored over a range of hole-diameters from to of the net width. While, in general, the presence of a hole causes a marked reduction in fatigue strength, the smallest holes result in only a slight reduction.

Exploratory Tests on the Effects of Random Loading and Corrosive Environment on the Fatigue Strength of Fillet-Welded Lap Joints

1975 ◽  
Vol 17 (4) ◽  
pp. 181-185 ◽  
Author(s):  
K. J. Marsh ◽  
T. Martin ◽  
J. McGregor
Keyword(s):  
Fatigue Strength ◽  
Mild Steel ◽  
Narrow Band ◽  
Fatigue Tests ◽  
Lap Joints ◽  
Corrosive Environment ◽  
Test Frequency ◽  
Constant Amplitude ◽  
Random Loading ◽  
Loading Tests

Fatigue tests on simple, fillet-welded, mild steel lap joints have been carried out to determine the effects of a corrosive environment and random loading. At normal testing frequencies, a brine-drip environment had no effect on the constant-amplitude fatigue strength at short endurances. At stresses less than the in-air fatigue limit, the corrosive environment was sufficient to allow crack growth at very low stress levels. In these corrosive environment tests, reducing the test frequency by a factor of 50 halved the life. The results of narrow-band random loading tests could be predicted reasonably accurately either by a fracture mechanics method or by Miner's rule.

Influence of Strength Level of Steels on Fatigue Strength and Fracture Morphology of Spot Welded Joints

2011 ◽  
Vol 462-463 ◽  
pp. 94-99
Author(s):  
Keiichiro Tohgo ◽  
Tomoya Ohguma ◽  
Yoshinobu Shimamura ◽  
Yoshifumi Ojima
Keyword(s):  
Finite Element ◽  
Fatigue Strength ◽  
Mild Steel ◽  
Welded Joints ◽  
High Strength ◽  
Fracture Morphology ◽  
Fatigue Tests ◽  
Finite Element Analyses ◽  
Ultra High Strength Steel ◽  
Spot Welded

In this paper, fatigue tests and finite element analyses are carried out on spot welded joints of mild steel (270MPa class) and ultra-high strength steel (980MPa class) in order to investigate the influence of strength level of base steels on fatigue strength and fracture morphology of spot welded joints. From the fatigue tests the following results are obtained: (1) Fatigue limit of spot welded joints is almost the same in both steels. (2) Fatigue fracture morphology of spot welded joints depends on the load level in the ultra-high strength steel, but not in the mild steel. From discussion based on the finite element analyses the following results are obtained: (3) The fatigue limit of spot welded joints can be predicted by stress intensity factors for a nugget edge, fracture criterion for a mixed mode crack and threshold value for fatigue crack growth in base steel. (4) Plastic deformation around a nugget in spot welded joints strongly affects the fatigue fracture morphology.

scholarly journals Investigation on Influence of Ultrasonic Impact Treatment (UIT) on Fatigue Life for Aluminium Alloy 2017-T4

2018 ◽  
Vol 21 (1) ◽  
pp. 141 ◽  
Author(s):  
Hussain J. M. Alalkawi ◽  
Aseel A. Alhamdany ◽  
Marib R. Abdul Hassan
Keyword(s):  
Mechanical Properties ◽  
Fatigue Life ◽  
Fatigue Strength ◽  
Ambient Temperature ◽  
Aluminium Alloy ◽  
Mechanical Design ◽  
Fatigue Tests ◽  
Strong Tendency ◽  
Ultrasonic Impact Treatment ◽  
Variable Amplitude

Improving fatigue life is one of the most important issues in mechanical design; an investigation has been conducted on Al 2017-T4. Group of samples have been machined and prepared, some of specimens have been treated using the ultrasonic impact treatment (UIT) with one line peening. The fatigue tests were carried out under constant and variable amplitude (R=-1) at ambient temperature, in order to find out the fatigue life S-N curve and strength after treatment. It has been found significant increasing in strength after it was treated by (UIT).  The fatigue strength is improved after treatment up to 4.16% at 107 cycles, enhancement are present with 24% and 18.78% for the cumulative fatigue lives low-high and high–low respectively.  These results also show a strong tendency of increasing of fatigue strength after application of (UIT) with increase in mechanical properties of material used.

The Size Effect in Fatigue of Plain and Notched Steel Specimens Loaded under Reversed Direct Stress

1951 ◽  
Vol 165 (1) ◽  
pp. 113-124 ◽  
Author(s):  
C. E. Phillips ◽  
R. B. Heywood
Keyword(s):  
Fatigue Strength ◽  
Size Effect ◽  
Mild Steel ◽  
Fatigue Limit ◽  
Laboratory Tests ◽  
Chromium Steel ◽  
Fatigue Tests ◽  
Strength Reduction ◽  
Engineering Practice ◽  
Nickel Chromium

The fatigue strength under reversed direct stress was ascertained for specimens of various diameters in the range from 0·19 inch to 2·4 inches, the largest diameter being determined by the capacity of the machines available. Two steels were used in this investigation—a 25-ton mild steel and a 65-ton, per cent nickel-chromium steel. The specimens were either plain or notched (transverse hole) and, as far as possible, geometrical similarity was preserved with regard to the transition radii and the diameter of the transverse hole. A few fatigue tests on other types of notch, such as a circumferential V-groove and a shoulder, were also carried out. No intrinsic size effect with either material was observed with the plain specimens. With transverse-hole specimens in mild steel, the fatigue limit was ±8·4 tons per sq. in. for specimens of 0·33 inch diameter, and 6·1 tons per sq. in. for specimens of 1·7 inches diameter, thus showing that an appreciable size effect was present. A similar size effect was found with the alloy steel specimens containing a transverse hole, and fatigue limits of ±17·1 and ±13·9 tons per sq. in. respectively were obtained for these two sizes of specimen. It is suggested that the low values of fatigue-strength reduction factors usually associated with mild steel as a result of laboratory tests do not apply to the larger sections of this material commonly employed in engineering practice.

Design Analysis and Fatigue Testing of the Typical Structural Details of Aluminium Ships

2018 ◽  
Author(s):  
Huilong Ren ◽  
Kaikai Ma ◽  
Chenfeng Li ◽  
Zhichao Zhang ◽  
Weijun Xu ◽  
...  
Keyword(s):  
Fatigue Strength ◽  
Aluminium Alloy ◽  
Fatigue Testing ◽  
Hot Spot ◽  
Fatigue Tests ◽  
Material Strength ◽  
Original Design ◽  
Hot Spot Stress ◽  
Strength Assessment ◽  
Structural Details

Aluminium alloy is widely used structural design in light-weighting design. Due to the material strength loss in welding, fatigue strength of typical joints fabricated by aluminium alloy is more sensitive than steel joints. The aim of this study is to investigate one aluminium detail of the longitudinal through the transverse, with high-performance of fatigue strength compared to the original design. The alloy of longitudinal is AA6082-T6 and the other components (including plate and transverse) is AA5083-H2. Firstly, eight schemes of structural details with various configurations of bracket and / or stiffener are designed. Based on the finite element analyses, the stress distribution of panels with eight designed details is obtained under typical loading condition respectively. According to the principle of hot spot stress being minimum, the optimal detail is determined, which using stiffener reinforced on both sides of transverse. Secondly, the fatigue tests of the optimal detail were designed and carried out. The testing panels consist of 2-span and 3 longitudinal stiffeners, and the frame with optimal joints is located in the middle of the panels. The test panels were simply supported at two ends with applied cyclic loading in the middle panel. According to the designed loading scheme (loading level, frequency, etc.), the fatigue tests of the panels with typical detail were carried out. The hot stress and the cycle times of the typical detail under different load levels were obtained. Based on the test data, the S-N curve of the typical detail in aluminium alloy is established. Finally, the fatigue strength assessment of the typical detail in target ship is performed based on the Miner’s linear cumulative damage theory and established S-N curve. The results show that the fatigue life of proposed optimal detail meets the design requirements of the target ship. The S-N curve of the typical detail made of AA6082-T6 obtained in this study can be also used for other aluminium ships with similar structural details.

Thermal Ageing Effects on the Residual Fatigue Strength of AA2618-T6511 Aluminium Alloy

2006 ◽  
Vol 324-325 ◽  
pp. 1095-1098 ◽  
Author(s):  
Pier Gabriele Molari ◽  
Piero Morelli ◽  
Sergio Maldotti ◽  
Tito Poli
Keyword(s):  
Fatigue Strength ◽  
Aluminium Alloy ◽  
Thermal Ageing ◽  
Fatigue Tests ◽  
Design Tool ◽  
Artificial Ageing ◽  
Thermal Cycles ◽  
Practical Applications ◽  
Rotating Machine ◽  
Residual Fatigue

This work presents the results of an experimental investigation on the effects of thermal ageing over the residual fatigue strength of AA2618-T6511 aluminium alloy. Among others, this kind of light alloy finds practical applications in highly stressed engine components, such as pistons, that are typically subjected to both thermal and fatigue loads. Thermal cycles are responsible for ageing phenomena, that involve the precipitation of silicates, with a corresponding progressive damage of the microstructure and weakening of the mechanical characteristics of the material. Artificial ageing has been reproduced in laboratory by means of thermal cycles controlled in time and temperature. These variables have been correlated to the hardness values measured on the surface of specimens. Bending fatigue tests have been performed on a rotating machine in a temperature controlled environment. The experimental S-N diagram is finally presented, as a function of the tested temperature, in order to provide a design tool for the fatigue life estimation of AA2618 components.

Influence of Milling and Abrasive Waterjet Cutting on the Fatigue Behaviour of DP600 Steel Sheet

2014 ◽  
Vol 891-892 ◽  
pp. 1761-1766 ◽  
Author(s):  
Pedro Duarte ◽  
Virgínia Infante ◽  
Manuel de Freitas
Keyword(s):  
Surface Roughness ◽  
Fatigue Strength ◽  
Steel Sheet ◽  
Fatigue Crack Initiation ◽  
Cutting Parameters ◽  
Fatigue Behaviour ◽  
Fatigue Tests ◽  
Abrasive Waterjet ◽  
Mechanical Parts ◽  
Waterjet Cutting

Theobservation of cracks in mechanical parts shows that cracks often initiate oncutting edges. A lot of effort has been done to developing theories to predictfatigue behaviour of welds. However for the cut-edges available data is veryscarce on the fatigue behaviour. Thispaper presents theresults obtained in fatigue tests on DP600 dual-phase steel sheet specimens, underthree types of cutting edges processes: milling with two cutting parameters andabrasive waterjet cutting. The tests were carried out using smooth specimens (Kt=1)and with a fatigue constant amplitude loading with R=0.1. Surface roughness andresidual stresses induced by these different cutting conditions were measuredand analysed. It was found that the fatigue strength of the abrasive waterjetcutting specimens was smaller than the predicted fatigue strength of themilling specimens and these may be attributed to the surface roughness inducedby the cutting process. Finally failure mechanisms were studied with the scanningelectron microscope (SEM) at fracture surfaces, including the identification ofthe fatigue crack initiation region. It was also observed that fatigue crackinitiation takes place on the cut-edges.

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