scholarly journals Fatigue Behaviour of Connectors used in Cable Harnessing through Cavity Formation Related Microstructural Degradation: A Failure Investigation Perspective

2022 ◽  
Vol 7 (1) ◽  
pp. 13-24
Author(s):  
Mrityunjoy Hazra ◽  
Ashok Kumar Singh
Keyword(s):  
Fatigue Loading ◽  
Fatigue Behaviour ◽  
Cavity Formation ◽  
Microstructural Degradation ◽  
Failure Investigation ◽  
Electrical Connector ◽  
Die Cast ◽  
Hardness Values ◽  
Fracture Features ◽  
Interconnected Pores

Two separately failed electrical connector pieces during a vibration test were received for failure analysis. Chemical composition, hardness values and microstructures of the each of the connector material indicate that the material of construction is a die cast aluminium-silicon type of alloy, closely matching with the standard ANSI/AA B380 alloy. Intergranular and faceted fracture features are observed and failure mechanism is found to be fatigue dominated. The connectors failed by impact fatigue arising out of the loosening of the connector assembly. This has happened by cavity formation and/or growth related microstructural degradation processes. Initial casting pores as well as microstructural degradations such as interconnected pores have developed in service and their successive growth, decohesion and interconnection of each of primary Si particles and Al-Fe-Mn precipitates (along precipitate-matrix interface) have led the initiation of the crack under fatigue loading. Brittle as-cast microstructure (as typified by the precipitate-matrix interfacial cracking), existing vibratory loading and absence of any rise in temperature in the system have assisted the initial cavity (crack) formation and/or growth. Moreover, initial fitment related looseness is an additional factor in initiating and propagating this damaging mechanism.

scholarly journals THE FATIGUE BEHAVIOUR OF GFRP BARS - EXPERIMENTAL STUDY

2019 ◽  
Vol 22 ◽  
pp. 38-47 ◽  
Author(s):  
Ondřej Januš ◽  
František Girgle ◽  
Iva Rozsypalová ◽  
Vojtěch Kostiha ◽  
Lenka Bodnárová ◽  
...  
Keyword(s):  
Fatigue Loading ◽  
Fatigue Behaviour ◽  
Interlaminar Shear Strength ◽  
Experimental Program ◽  
Matrix Interface ◽  
Interface Damage ◽  
Gfrp Bars ◽  
Interlaminar Shear ◽  
Fibre Matrix

The paper describes an experimental program for studying the fatigue performance of GFRP bars, which has been initiated by the authors. Two different test configurations were used to assess the fatigue behaviour. The bare specimens were tested within the first series. A modified gripping system was used to reduce eccentricity when the bar was not directly fixed. However, the boundary conditions seem to affect the results. The second series consisted of a set of specimens of bars embedded in concrete. This configuration seems appropriate for determination of fatigue life of GFRP bars. Two S-N curves for bare bars and bars embedded in concrete were created and compared. Significant reduction of interlaminar shear strength at the beginning of fatigue loading proved matrix or fibre/matrix interface damage.

scholarly journals Effect of Alternating Magnetic Field on the Fatigue Behaviour of EN8 Steel and 2014-T6 Aluminium Alloy

Metals ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 984 ◽  
Author(s):  
Akram ◽  
Babutskyi ◽  
Chrysanthou ◽  
Montalvão ◽  
Pizurova
Keyword(s):  
Magnetic Field ◽  
Electron Microscopy ◽  
Fatigue Behaviour ◽  
Alternating Magnetic Field ◽  
X Ray Diffraction ◽  
Secondary Precipitation ◽  
Transmission Electron ◽  
Fatigue Endurance ◽  
Fracture Features ◽  
Compressive Residual Stresses

The application of an alternating magnetic field (0.54 T) was observed to lead to an improvement in the fatigue endurance and an increase in Vickers microhardness and tensile strength of both EN8 steel and AA2014-T6 alloy. Fractography using scanning electron microscopy showed evidence of more ductile fracture features after treatment in contrast to untreated samples. The results of X-ray diffraction indicated formation of more compressive residual stresses following treatment; while examination by transmission electron microscopy showed evidence of fewer dislocations. In the case of the AA2014-T6 alloy; Guinier-Preston (GP) zones were also generated by the alternating magnetic field. However; the temperature increase during the treatment was too low to explain these observations. The results were attributed to the non-thermal effect of the alternating magnetic field treatment that led to depinning and movement of dislocations and secondary precipitation of copper.

Effect of sulphate attack on the flexural fatigue behaviour of fly ash–based geopolymer concrete

2018 ◽  
Vol 53 (8) ◽  
pp. 711-718 ◽  
Author(s):  
Tao Long ◽  
Hongen Zhang ◽  
Yu Chen ◽  
Zhi Li ◽  
Jiageng Xu ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Fly Ash ◽  
Damage Index ◽  
Fatigue Loading ◽  
Fatigue Behaviour ◽  
Distribution Model ◽  
Geopolymer Concrete ◽  
Sulphate Attack ◽  
Flexural Fatigue ◽  
Erosion Effect

In this work, the erosion effect of sulphate solution on the flexural fatigue behaviour of fly ash–based geopolymer concrete was investigated. Under cyclic bending loading, the effect of sulphate attack on the fatigue life of geopolymer concrete was analysed using the static flexural strength as the damage index. Results revealed that the fatigue life of geopolymer concrete after sulphate erosion was significantly reduced compared with uncorroded samples under the same fatigue loading condition. And the fatigue life of corroded/uncorroded geopolymer concrete can be approximately described by the two-parameter Weibull distribution model. Since the sulphate attack would increase the actual stress level of corroded geopolymer concrete, a fatigue equation considering the damage index was deduced to predict the fatigue life of geopolymer concrete after sulphate attack.

Corrosion Fatigue of Welded Stainless Steels for Deepwater Riser Applications

2005 ◽  
Author(s):  
P. Woollin ◽  
S. J. Maddox ◽  
D. J. Baxter
Keyword(s):  
Corrosion Fatigue ◽  
Oil And Gas ◽  
Current Knowledge ◽  
Fatigue Loading ◽  
Fatigue Behaviour ◽  
Gas Field ◽  
Internal Surfaces ◽  
Oil And Gas Field ◽  
Offshore Oil And Gas ◽  
Offshore Oil

Steel risers for deepwater offshore oil and gas field developments are subject to seawater on the external surfaces, produced fluids on the internal surfaces and to fatigue loading. This paper reviews current knowledge of the corrosion fatigue behaviour of welded stainless steel for risers and presents results of testing of supermartensitic, duplex and superduplex grades in relevant environments.

scholarly journals Fatigue behaviour of fibre-reinforced composite T-joints

2018 ◽  
Vol 165 ◽  
pp. 07004
Author(s):  
Ying Wang ◽  
Constantinos Soutis
Keyword(s):  
Fatigue Life ◽  
Testing Machine ◽  
Fatigue Loading ◽  
Maximum Load ◽  
Fatigue Behaviour ◽  
Control Mode ◽  
Static Properties ◽  
T Joints ◽  
Pull Out ◽  
Reinforced Composite

In this paper a study was carried out on the fatigue life of fibre-reinforced composite T-joints subjected to a tensile pull-out loading. The composite T-joints have been made of glass fabric infused with epoxy resin using a vacuum assisted resin transfer moulding technique. Methods such as the use of veil layers, tufting techniques and 3D weave have been employed to improve the interlaminar fracture toughness of the composite T-joints. All the tests were conducted in an Instron testing machine using a specially designed test fixture. Fatigue tests were performed in a load control mode with a stress ratio of R = σmin/σmax = 0.1. The cyclic loading pattern was a sinusoidal wave with a frequency of 6 Hz. The specimens were cycled at a series of constant maximum load values up to failure. Fatigue loads versus life data for each T-joint type were produced at various maximum applied loads. The 3D weave T-joints were found to have the best performance in both static and fatigue loading. Increasing the static properties increases fatigue life performance; the increasing rate in fatigue life is changed with the number of stress cycles. The location for the through-thickness reinforcement plays an important role in improving fatigue life of the Tjoints. Fatigue life is significantly improved if the web is reinforced in through-thickness direction. A finite element (FE) failure model was also created using ABAQUS to determine the location where delamination is initiated and its subsequent propagation.

Failure Investigation of an AlSi9Cu3 Alloy Die-Cast Cavity Insert

2017 ◽  
Vol 17 (6) ◽  
pp. 1251-1259
Author(s):  
Xu Li ◽  
Bao-sheng Liu ◽  
Li-feng Hou ◽  
Ying-hui Wei ◽  
Yi-de Wang
Keyword(s):  
Failure Investigation ◽  
Die Cast

Corrosion Fatigue of Welded C-Mn Steel Risers for Deepwater Applications: A State of the Art Review

2005 ◽  
Author(s):  
S. J. Maddox ◽  
R. J. Pargeter ◽  
P. Woollin
Keyword(s):  
Oil And Gas ◽  
Current Knowledge ◽  
Fatigue Loading ◽  
Fatigue Behaviour ◽  
Manganese Steel ◽  
Gas Field ◽  
Internal Surfaces ◽  
Oil And Gas Field ◽  
Offshore Oil And Gas ◽  
Girth Welds

Steel risers for deepwater offshore oil and gas field developments are subject to seawater on the external surfaces, produced fluids on the internal surfaces and to fatigue loading. This paper reviews current knowledge of the fatigue behaviour of welded carbon-manganese steel for risers in relevant environments. A substantial body of data exists relating to the performance of girth welds in seawater with cathodic protection and consequently recent attention has been turned to establishing the fatigue performance in the internal environment, which may contain water, CO2, H2S and chloride and bicarbonate ions.

scholarly journals Comparative Study on the Fatigue Behaviour of SCC and VC

2014 ◽  
Vol 627 ◽  
pp. 333-336 ◽  
Author(s):  
Sara Korte ◽  
Veerle Boel ◽  
Wouter de Corte ◽  
Geert de Schutter
Keyword(s):  
Crack Width ◽  
Static Load ◽  
Fatigue Loading ◽  
Fatigue Behaviour ◽  
Self Compacting Concrete ◽  
Irreversible Damage ◽  
Bending Tests ◽  
Loading Rates ◽  
Four Point Bending ◽  
Concrete Type

Continuous cyclic loading on concrete constructions involves a progressive cracking mechanism, leading to significant changes of the material properties during the lifetime of the structure. Gradually, irreversible damage is inflicted and the carrying capacity is affected, which may cause structural collapse at a stress or strain level much lower than in case of a single static load. This so-called fatigue phenomenon is well-documented in literature for traditional, vibrated concrete (VC), but this is not the case for self-compacting concrete (SCC). Given the fact that this latter concrete type is already used worldwide in many types of structures, including cyclically loaded ones, a good knowledge and understanding of the static and fatigue material behaviour is crucial. Up till now, it is unsure whether SCC performs better, worse, or equally under fatigue loading conditions. Therefore, in this study, destructive four-point bending tests are performed on large beams, made from VC and SCC, both statically and cyclically (at different loading rates). A comparison of the deflection, strain, crack pattern and crack width evolution of the different concrete types is made. The results reveal some significant differences regarding concrete strain and crack width development during the cyclic tests.

scholarly journals Microstructural Control of Fatigue Behaviour in a Novel  Titanium Alloy

Metals ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 1200
Author(s):  
Bache ◽  
Davies ◽  
Davey ◽  
Thomas ◽  
Berment-Parr
Keyword(s):  
Titanium Alloy ◽  
Fatigue Crack ◽  
Mechanical Performance ◽  
Fatigue Crack Initiation ◽  
Fatigue Loading ◽  
Fatigue Behaviour ◽  
Fracture Mechanisms ◽  
Mechanical Processing ◽  
Detailed Assessment ◽  
Propagation Properties

The novel titanium alloy TIMETAL® 407 (Ti-407) has been developed as an alternative to Ti-6Al-4V (Ti-6-4), for applications that demand relatively high ductility and energy absorption. Demonstrating a combination of lower strength and greater ductility, the alloy introduces a variety of cost reduction opportunities, including improved machinability. Thermo-mechanical processing and its effects on microstructure and subsequent mechanical performance are characterised, including a detailed assessment of the fatigue and crack propagation properties. Demonstrating relatively strong behaviour under high-cycle fatigue loading, Ti-407 is nevertheless susceptible to time-dependent fatigue effects. Its sensitivity to dwell loading is quantified, and the associated deformation and fracture mechanisms responsible for controlling fatigue life are explored. The intimate relationship between thermo-mechanical processing, micro-texture and fatigue crack initiation through the generation of quasi-cleavage facets is highlighted. Consistent fatigue crack growth kinetics are demonstrated, independent of local microstructure.

Reduction in Fatigue Strength of Arc Welded Aluminium 5083-H111 on Immersion in NaCl

2014 ◽  
Vol 891-892 ◽  
pp. 1469-1475
Author(s):  
Madeleine du Toit ◽  
Kalenda Mutombo
Keyword(s):  
Sea Water ◽  
Base Material ◽  
Fatigue Loading ◽  
Ambient Air ◽  
Fatigue Behaviour ◽  
Design Codes ◽  
Corrosive Environment ◽  
Nacl Solution ◽  
Fatigue Design ◽  
Reference Curves

The design of welded aluminium structures subjected to fatigue loading is usually carried out on the basis of reference fatigue curves published in design codes. The reference curves are usually relevant to dynamic loading in ambient air and make provision for the presence of a corrosive environment by downgrading the detail category for a particular joint type. This investigation studied the corrosion-fatigue behaviour of Al 5083-H111 welded using ER5356 wire. Comparison between experimentally determined fatigue curves and reference fatigue design curves published in Eurocode 9 confirms that 5083-H111 welds display significantly lower reference fatigue strengths than unwelded base material. Immersion in a NaCl solution during testing reduced the reference fatigue strengths even further. The reduction in detail category number recommended in Eurocode 9 for aluminium butt welds on immersion in sea water appears suitable (or even marginally conservative) for the 5XXX series Al-Mg-Mn welds examined in this investigation.

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