Experimental Investigation of Fatigue Performance of a 300 mm2 Copper Power Conductor

2013 ◽  
Author(s):  
Fachri P. Nasution ◽  
Svein Sævik ◽  
Stig Berge
Keyword(s):  
Fatigue Strength ◽  
Cross Section ◽  
Fatigue Crack Initiation ◽  
Fatigue Performance ◽  
Power Cables ◽  
Floating Structure ◽  
Copper Conductor ◽  
Sea Bed ◽  
Full Cross Section ◽  
The Waves

Electrical power cables are used in conjunction with floating units for provision of energy to installations on the sea bed, power from land to the floater, or export of power from a wind turbine to land. Power cables that are linked to a floating unit are subjected to fatigue loading from the waves and due to the movement of the vessel in the waves. Fatigue strength needs to be verified for design. Fatigue performance of a 300 mm2 stranded copper conductor was investigated. The experimental work included fatigue tests of individual wires and full cross section conductors including unlubricated and lubricated conductors. Individual wires from different layers were tested in tension-tension mode with stress ratio R = 0.1. Full cross-section conductors were tested in cyclic reversed bending with constant tension at ends, simulating the loading at the top end of a conductor hanging off a floating structure through a bellmouth. The objective of this paper is experimental assessment of the fatigue strength of a 300 mm2 copper conductor and to investigation of the mechanisms of fatigue crack initiation and growth in individual wires. At the time of submission the test program was still in progress, and conclusions are tentative only. An updated paper with complete results will be published at a later stage.

Fatigue Strength of Formable Ultra High-Strength TRIP-Aided Steels with Bainitic Ferrite Matrix

2007 ◽  
Vol 345-346 ◽  
pp. 247-250 ◽  
Author(s):  
Koh Ichi Sugimoto ◽  
Junji Tsuruta ◽  
Sung Moo Song
Keyword(s):  
Fatigue Strength ◽  
Fatigue Limit ◽  
Retained Austenite ◽  
Fatigue Crack Initiation ◽  
Bainitic Ferrite ◽  
High Strength ◽  
Ferrite Matrix ◽  
Fatigue Performance ◽  
Refined Microstructure ◽  
High Fatigue

Formable ultra high-strength TRIP-aided steel with bainitic ferrite matrix structure (TBF steel) contributes to a drastic weight reduction and an improvement of crash safety of automobile. In this study, fatigue strength of 0.2%C-1.5%Si-1.5%Mn TBF steels was investigated. High fatigue limit was achieved in TBF steels austempered at 400-450oC, containing a large amount of stable retained austenite. The fatigue limit was linearly related with mobile dislocation density, as well as TRIP effect of retained austenite. When compared to conventional martensitic steel, the TBF steel exhibited lower notch-sensitivity or higher notched fatigue performance. Complex additions of 0.5%Al, 0.05%Nb and 0.2%Mo considerably improved the notched fatigue performance, as well as the smooth fatigue strength. This was associated with the stabilized retained austenite and refined microstructure which suppress fatigue crack initiation and/or propagation.

scholarly journals Effect of micro-notches on fatigue strength of electrodeposited nanocrystalline nickel thin films

2018 ◽  
Vol 165 ◽  
pp. 04011
Author(s):  
Keisuke Tanaka ◽  
Yuta Murase ◽  
Hirohisa Kimachi
Keyword(s):  
Thin Films ◽  
Fatigue Strength ◽  
Fatigue Limit ◽  
Stress Ratio ◽  
Fatigue Crack Initiation ◽  
Fatigue Tests ◽  
Fine Grained ◽  
Nickel Thin Films ◽  
Nano Crystalline ◽  
Fictitious Crack

The effect of micro-notches on the fatigue strength of nickel thin films was studied. Two types of thin films with 10 μm thickness were produced by electrodeposition using sulfamate solution without and with brightener: ultra-fine grained film (UFG) with the grain size of 384 nm and nano-crystalline grained film (NCG) with that of 17 nm. Micro-sized notches introduced by FIB had the width of 2 μm and various depths from 8 to 150μm. Fatigue tests were conducted under the stress ratio of 0.1. The fatigue strength decreased with increasing depth of notches. NCG had much higher strength than UFG compared at the same notch depth. Notches as small as 8μm did reduce the fatigue strength of both UFG and NCG. The fatigue limit was controlled by the initiation of cracks and no non-propagating crack was observed in specimens fatigued below the fatigue limit. A model of fictitious crack successfully predicted the reduction of the fatigue limit due to micro-notches. The characteristic crack length of NCG was much smaller than the UFG, while the fatigue strength of defect-free NCG was larger than that of UFG. SEM observation of fracture surfaces was conducted to reveal micromechanisms of fatigue crack initiation.

An Investigation Into the Non-Linear Effects Resulting From Air Cushions in the Orecon Oscillating Water Column (OWC) Device

2009 ◽  
Author(s):  
Jim L. Lye ◽  
David T. Brown ◽  
Fraser Johnson
Keyword(s):  
Water Column ◽  
Mooring Line ◽  
Oscillating Water Column ◽  
Trapped Air ◽  
Model Scale ◽  
Sea Bed ◽  
Structural Responses ◽  
Linear Effects ◽  
The Waves ◽  
Base Structure

When designing an Oscillating Water Column (OWC) device, the motions and structural responses in waves are of great interest. However, predictions of these motions are complicated by the presence of air chambers above a large proportion of the waterplane area. Modeling the stiffness provided by air cushions at model scale presents a number of problems as air stiffness does not scale according to the laws of Froude scaling. To-date, the closest analogy might be an air-lifted gravity base structure, or crane vessel. However, in an OWC device, the air is not trapped as it is allowed to vent through a turbine. As a result, in still water, none of the mass of the buoy is supported by the air column. However, as the buoy is subjected to waves of increasing height the influence of the air chambers on the motions response becomes more pronounced. Experiments into the behavior of structures with trapped air springs have focused largely on benign sea conditions as the air cushions are generally used in vessels or structures involved with installation operations or similar. In contrast, the behavior of an OWC device must be predicted in all conditions up to, and including, survival conditions. BPP-TECH are providing technical support to the designers of the Orecon MRC wave energy buoy. This buoy uses chambers of varying drafts to generate electricity from the waves. The buoy is tension moored to the sea bed in order to constrain the heave motions to maximize the air pressure within the chambers as waves pass. A series of tank tests were undertaken at the OCEANIDE facility in order to investigate the motions of the buoy while tension moored and also measure the mooring line tensions. This paper will focus on the methods used to represent the air chambers at model scale and will present the results of the tests. A variety of different orifice sizes were used in the test campaign in order to provide a spread of values that would offer an insight into the effect of the air chambers on the motions of the structure in waves.

scholarly journals Fatigue Strength Analysis and Fatigue Damage Evaluation of Roller Chain

Metals ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 847 ◽  
Author(s):  
Ryoichi Saito ◽  
Nao-Aki Noda ◽  
Yoshikazu Sano ◽  
Jian Song ◽  
Takeru Minami ◽  
...  
Keyword(s):  
Fatigue Crack ◽  
Fatigue Strength ◽  
Fatigue Damage ◽  
Fatigue Crack Initiation ◽  
Strength Analysis ◽  
The Finite Element Method ◽  
Roller Chain ◽  
Press Fitting ◽  
The Press ◽  
Static Tensile

This paper deals with the roller chain commonly used for transmission of mechanical power on many kinds of industrial machinery, including conveyors, cars, motorcycles, bicycles, and so forth. It consists of a series of four components called a pin, a bush, a plate, and a roller, which are driven by a sprocket. To clarify the fatigue damage, in this paper, the finite element method (FEM) is applied to those components under three different types of states, that is, the press-fitting state, the static tensile state, and the sprocket-engaging state. By comparing those states, the stress amplitude and the average stress of each component are calculated and plotted on the fatigue limit diagram. The effect of the plastic zone on the fatigue strength is also discussed. The results show that the fatigue crack initiation may start around the middle inner surface of the bush. As am example, the FEM results show that the fatigue crack of the inner plate may start from a certain point at the hole edge. The results agree with the actual fractured position in roller chains used in industry.

Influence of Inner Surface Defects on the Fatigue Strength of Pipe Subjected to Cyclic Internal Pressure

1978 ◽  
Vol 100 (4) ◽  
pp. 360-368
Author(s):  
Y. Yazaki ◽  
S. Hashirizaki ◽  
S. Nishida ◽  
C. Urashima
Keyword(s):  
Fatigue Strength ◽  
Internal Pressure ◽  
Test Specimen ◽  
Surface Defects ◽  
Fatigue Crack Initiation ◽  
Internal Surface ◽  
Fatigue Tests ◽  
Inner Surface ◽  
Surface Notch ◽  
Medium Diameter

Cyclic internal oil pressure fatigue tests were carried out on medium-diameter ERW pipes of API 5LX - X60 in an attempt to determine the influence of surface defects on the fatigue strength. Experimental factors investigated were the depth and location of internal surface notch in relation to the axis of pipe. The specimen was subjected to cyclic internal pressure, the cyclic rate being 0.3–0.5 Hz. During the test, Acoustic Emission (AE) techniques were applied to detect the fatigue crack initiation. Along with the aforementioned fatigue tests, pulsating tension fatigue tests were carried out on specimens with the same surface notches as the cyclic internal pressure fatigue test specimen.

The effect on the fatigue strength of bone cement of adding sodium fluoride

2001 ◽  
Vol 215 (2) ◽  
pp. 251-253 ◽  
Author(s):  
C Minari ◽  
M Baleanil ◽  
L Cristofolini ◽  
F Baruffaldi
Keyword(s):  
Fatigue Strength ◽  
Bone Cement ◽  
Sodium Fluoride ◽  
Biomedical Applications ◽  
Cement Mantle ◽  
Fatigue Tests ◽  
Fatigue Performance ◽  
Bone Cements ◽  
The Novel ◽  
Pmma Bone Cement

New bone cements that include several additives are currently being investigated and tested. One such additive is sodium fluoride (NaF), which promotes bone formation, facilitating implant integration and success. The influence of NaF on the fatigue performance of the cement as used in biomedical applications was tested in this paper. In fact fatigue failure of the cement mantle is a major factor limiting the longevity of a cemented implant. An experimental bone cement with added NaF (12wt%) was investigated. The fatigue strength of the novel bone cement was evaluated in comparison with the cement without additives; fatigue tests were conducted according to current standards. The load levels were arranged based on a validated, statistically based optimization algorithm. The curve of stress against number of load cycles and the endurance limit were obtained and compared for both formulations. The results showed that the addition of NaF (12 wt %) to polymethylmethacrylate (PMMA) bone cement does not affect the fatigue resistance of the material. Sodium fluoride can safely be added to the bone cement without altering the fatigue performance of the PMMA bone cement.

Effect of Processing Layer on Fatigue Strength of Extruded AZ61 Magnesium Alloy

2013 ◽  
Vol 577-578 ◽  
pp. 429-432 ◽  
Author(s):  
Yukio Miyashita ◽  
Kyohei Kushihata ◽  
Toshifumi Kakiuchi ◽  
Mitsuhiro Kiyohara
Keyword(s):  
Fatigue Crack ◽  
Fatigue Life ◽  
Fatigue Strength ◽  
Magnesium Alloy ◽  
Crack Initiation ◽  
Crack Growth ◽  
Fatigue Crack Initiation ◽  
Fatigue Tests ◽  
Crack Growth Resistance ◽  
Az61 Magnesium Alloy

Fatigue Property of an Extruded AZ61 Magnesium Alloy with the Processing Layer Introduced by Machining was Investigated. Rotating Bending Fatigue Tests were Carried out with the Specimen with and without the Processing Layer. According to Results of the Fatigue Tests, Fatigue Life Significantly Increased by Introducing the Processing Layer to the Specimen Surface. Fatigue Crack Initiation and Propagation Behaviors were Observed by Replication Technique during the Fatigue Test. Fatigue Crack Initiation Life of the Specimen with the Processing Layer was Slightly Longer than that of the Specimen without the Processing Layer. Higher Fatigue Crack Growth Resistance was also Observed when the Fatigue Crack was Growing in the Processing Layer in the Specimen with the Processing Layer. the Longer Fatigue Life Observed in the Fatigue Test in the Specimen with the Processing Layer could be Mainly due to the Higher Crack Growth Resistance. it is Speculated that the Fatigue Strength can be Controlled by Change in Condition of Machining Process. it could be Effective way in Industry to Improved Fatigue Strength only by the Cutting Process without Additional Surface Treatment Process.

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