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Experimental And Numerical Studies On Multistage Strength Degradation In Notched Concrete Beams Under Repeated Loads: A Review
Authors: Masaaki Nakano, Zihai Shi, Yukari Nakamura, Cuiping Liu, Hiroshi Tanaka
The multistage strength degradation theory states that fatigue is caused by the sporadic sudden change o f c racking behaviour in a system under cyclic loading, leading to intermittent strength reduction of the system and its eventual failure. To prove this theory, an experimental study on the load-carrying capacity of notched concrete beams was carried out first, in which the sizes of several notches were enlarged sequentially to simulate the growth of cracks under repeated loading
Strain Energy Diagram For Characterising Fatigue Behaviour In Structural Members And Machine Parts Subjected To Repeated Loads
Authors: Zihai Shi, Yukari Nakamura, Masaaki Nakano
According to the multistage strength degradation theory which has recently emerged from studies on the material and structural behaviour of concrete, fatigue is caused by the sporadic sudden change of cracking behaviour in a system under cyclic loading, leading to intermittent strength reduction of the system and its eventual failure. Here we report a new finding on the waveform variation of the maximum strain energy along the axis of load cycles in a structural member or machine part under fatigue.
Authors: K. Manigandan and T. S. Srivatsan V. K. Vasudevan, D. Tammana and B. Poorbangi
In this paper, the results of a study on microstructural influences on cyclic strain response, deformation and fracture behavior of an alloy steel is presented Cyclic strain resistance exhibited a linear trend for the variation of both elastic strain amplitude with reversals-to-failure, and plastic strain amplitude with reversals-to-failure.
Authors: M. Phillips, K. McLaughlin, D. Ojeda, E. Luna, M. Burke, P. Cruz, K. Featherstone, E. Petersen, P.D. Ferro
Bending fatigue samples were plasma cut and water jet cut from sheets of 304 stainless. Samples were exposed to high pressure hydrogen (138 MPa at 300C for three weeks) or 1 atm hydrogen at room temperature for one week, or were unexposed. Preliminary results from bending fatigue testing show a decrease in fatigue life for hydrogen supersaturated samples.
Influence Of Long Term Ageing On Fatigue Crack Growth Behavior Of P91 Steel At Different Temperatures
Authors: M. Nani Babu, S. K. Swain, B. Shashank Dutt, S. Venugopal, G. Sasikala
Fatigue crack growth behavior (FCG) of Modified 9Cr-1Mo (P91) steel has been evaluated at 300, 653 and 823 K in normalized and tempered (unaged) and in subsequently aged at 823 K for 20000 h (aged) condition in both Paris and threshold regimes. The effects of test temperature and ageing on the FCG resistance of the material have been rationalized by examining the behavior using different measures of driving forces, namely, the applied and effective stress intensity factor ranges AK and AKeff, and the crack tip stress intensity factor range AKtip,ef that takes in to account the stress shielding effects also.
Multistage Strength Degradation In S25C Steel Under Torsional Cyclic Loading And Its Engineering Applications
Authors: Zihai Shi, Masaaki Nakano, Cuiping Liu
An experimental investigation on the fatigue mechanism of metal is reported. In this experimental study, multiple identical test specimens were first preloaded with torsional cyclic loads of increasing number of load cycles, and then tension tests were carried out to obtain their tensile strengths. The obtained test results presented strong experimental evidence for the existence of multistage strength degradation processes in metals under cyclic loading, and the strength degradation was clearly triggered by an abrupt change of cracking behaviour.
Authors: K. Manigandan, T.S. Srivatsan, G. Doll, and T. Quick
In this manuscript the results of a study aimed at understanding the extrinsic influence of test specimen orientation, with respect to wrought alloy steel plate, on high cycle fatigue properties and fracture behavior is highlighted. The alloy steel chosen was 300 M. Samples of this alloy steel prepared from both the longitudinal and transverse orientation were cyclically deformed over a range of maximum stress and the corresponding number of cycles to failure (NF) was recorded.
The Effects Of Pre-Straining Conditions On Austenite Stability During Fatigue Of Multiphase Trip Steels
Authors: Alexander L. Ly and Kip O. Findley
A multiphase TRIP780 steel was subjected to tensile pre-strains of 0, 5, and 15% at room temperature and at -20 °C. The pre-strained specimens were subjected to strain-controlled, fully reversed, axial fatigue testing at strain amplitudes ranging from 0.2 to 0.6%. The low-cycle fatigue life was largely independent of the pre-strain history.
Authors: Sulaiman Abdulkareem, A.T. Abdulrahim, S. I. Talabi and O. H. Amuda
This paper investigated the effect of heat treatment operations on the fatigue resistance of low carbon steel. Specimens after preparation for fatigue testing were subjected to annealing, normalizing and quenching heat treatment. Results show that the annealed specimen had the largest number of cycles to failure, indicating a high fatigue resistance.
Authors: J. Toribio, V. Kharin
Plasticity-induced crack closure (PICC) has long been focused as supposedly controlling factor of fatigue crack growth (FCG). However, when the plane-strain near-tip constraint is approached, PICC lacks of straightforward evidence, so that its significance in FCG, and even the very existence, remain debatable. To add insights into this matter, large-deformation elastoplastic simulations of plane-strain crack under constant amplitude load cycling at different load ranges and ratios, as well as with an overload, have been performed.