Comet aircraft failures 1950s Fatigue crack initiation in pressurized skins due to high gross stresses and stress- concentration effects from geometric features Development of the fatigue "safe-life" approach Evaluation of the effects of geometry and notches on fatigue behavior Evaluation of the effects of stiffeners on stress distribution
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Fatigue testing of smooth specimen and cracked specimen will be performed to determine the parameters affecting crack initiation life and crack growth rate. Crack behaviour simulation involves incorporating lab and field data into a finite element model of the boom structure and run different crack propagation scenarios to predict failure. 2.
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equipment used in the agricultural industries, road sign portals,lighting poles, bridges, towers and mining equipment.The cyclic loading in these structural systems typically produces high cycle fatigue behavior resulting in failures after tens of thousands millions …
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Large-capacity rope shovels are used as primary production equipment in many surface mining operations. Current rope shovels have payload capacities in excess of 100 tons per pass. The dynamic payload and formation resistive forces result in severe stress loading of the shovel front-end assembly. Material flaws, high stresses, and harsh excavation conditions can initiate …
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In-service behavior of bucket wheel excavator (BWE) and other equipment operating on surface mines (bucket chain excavators, spreaders, and failures of surface mine equipment occur in service, significant causing two separated fatigue cracks 1 in an early step and merged in a dominant fatigue crack 2 (Fig. 11).
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Oct 26, 2021 · The fatigue crack propagation behavior of WAAM built parts using titanium Ti-6Al-4 V alloy was examined by Zhang et al., 18 where compact tension, C(T), specimens were extracted from WAAM walls. The specimens had different orientations with the crack initiation region in substrate or the WAAM built area.
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can vary from extremely small cracks, for example, from within a weld arc strike (as was the case in the brittle fracture of a T-2 tanker during World War II), to much larger weld or fatigue cracks. Even though only small flaws may be present initially, repeated loading (fa tigue), or stress corrosion can cause them to enlarge,
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Fatigue crack growth behavior in weld-repaired high-strength mining equipments, lifting equipments, storage tanks, excavator buckets, high rise buildings and induced draft fans [1,2
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Near-threshold Fatigue Crack Growth Behavior in Welded Joint of NiCrMoV Rotor SteelCN
Get a QuoteTests that refer to the growth of the fatigue crack located at the welded joint have been carried out by bending at three points with asymmetric load R = 0.5 (R = σ min / …
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Fatigue Failure and Testing Methods 5 2.2 Different phases of fatigue life Microscopic investigation in the 20th century has revealed that the nucleation of fatigue cracks occurs at a very early stage of fatigue life.
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Jan 01, 2008 · The harsh conditions under which the excavators operate are conducive to the formation of fatigue cracks. Most of these fatigue cracks are two-tip corner cracks located in the crack region shown in Fig. 3, where the section of the boom is a twin box section as shown in Fig. 4. Each box section is 1.035 m wide and the height of the section within that region varies from …
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Dec 02, 2021 · The fatigue crack propagation law becomes a straight line in a double logarithmic plot. In the area shaded in blue, the load peak has a linear–elastic stress intensity factor K max > K IC. In this area, even linear–elastic crack initiation or even specimen failure can be expected (in the elastic–plastic calculation, initiation can be
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In this paper are presented results of tests and analyses of complex dynamic loads carried out on the bucket-wheel excavator SchRs 650/5 × 24 Krupp, as well as assessment of …
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The growth or extension of a fatigue crack under cyclic loading is principally controlled by maximum load and stress ratio. However, as in crack initiation, there are a number of additional factors that may exert a strong influence, includ ing environment, frequency, temperature, and grain direction. Fatigue crack propagation test
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Jan 01, 2014 · Keywords: Bucket wheel excavator, structure, fatigue fracture 1. Introduction In-service behaviour of bucket wheel excavator (BWE), aimed to supply electrical power plants by coal, depends on * Darko Danicic. Tel.: +381648361474; fax: +381118120127. E-mail address: [email protected]
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Mar 24, 2021 · The concept of fatigue hydraulic fracturing serves as a possible explanation for such rock behaviour by making use of depressurisation phases to relax crack-tip stresses. During hydraulic fatigue
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The operator of an excavator is responsible for safe operation of the machine and the safety of those working in the vicinity of it. Several factors can affect an operator's ability to stay focused on operating their machine. • Fatigue & Hunger: Fatigue can result from working too many hours, lack of sleep, hunger or monotonous, repetitive
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In both cases there is a notch where a fatigue crack initiates. For the weld it is the weld toe and for the bolt it is the thread root. Due to the presence of the notch and the resulting high stress concentration factor, the fatigue behaviour is in most cases hardly affected by: The mean stress level; The material quality.
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Jul 02, 2014 · perpendicularly to the load can actually crack or debond from the matrix. 3. Gray iron is stiffer in compression than tension because the spaces occupied by the graphite do not see corresponding decreases in volume.
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