The Experts below are selected from a list of 111957 Experts worldwide ranked by ideXlab platform
Habiba Bougherara - One of the best experts on this subject based on the ideXlab platform.
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use of infrared thermography to investigate the Fatigue behavior of a carbon fiber reinforced polymer composite
Composite Structures, 2013Co-Authors: John Montesano, Zouheir Fawaz, Habiba BougheraraAbstract:Abstract Thermography was used to investigate the Fatigue behavior of a braided carbon fiber polymeric composite plate. A thermographic approach, originally developed in an earlier study for metallic alloys, was employed to rapidly determine the composite high cycle Fatigue strength. The method yielded a Fatigue threshold value that was in excellent agreement with that obtained through a conventional experimental test program. The damage mechanisms responsible for the increased heat dissipation and ultimately failure were identified, which provides support for the existence of a Fatigue threshold for this material. An extension of the thermographic technique to rapidly determine the entire Fatigue Stress-life curve for the composite plate provided a direct correlation to the Stress-life curve determined through a conventional test program. Energy dissipation was also used as an indicator to determine the high cycle Fatigue strength, providing support for the thermographic approach. A relationship between the dissipated heat, the intrinsic energy dissipation and the number of cycles to failure has been clearly established.
C L Williams - One of the best experts on this subject based on the ideXlab platform.
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estimating the Fatigue Stress concentration factor of machined surfaces
International Journal of Fatigue, 2002Co-Authors: Dwayne Arola, C L WilliamsAbstract:Abstract In this study the effects of surface texture on the Fatigue life of a high-strength low-alloy steel were evaluated in terms of the apparent Fatigue Stress concentration. An abrasive waterjet was used to machine uniaxial dogbone Fatigue specimens with specific surface quality from a rolled sheet of AISI 4130 CR steel. The surface texture resulting from machining was characterized using contact profilometry and the surface roughness parameters were used in estimating effective Stress concentration factors using the Neuber rule and Arola–Ramulu model. The steel specimens were subjected to tension–tension axial Fatigue to failure and changes in the Fatigue strength resulting from the surface texture were assessed throughout the Stress–life regime (103≤Nf≤106 cycles). It was found that the Fatigue life of AISI 4130 is surface-texture-dependent and that the Fatigue strength decreased with an increase in surface roughness. The Fatigue Stress concentration factor (Kf) of the machined surfaces determined from experiments was found to range from 1.01 to 1.08. Predictions for the effective Fatigue Stress concentration ( K f ) using the Arola–Ramulu model were within 2% of the apparent Fatigue Stress concentration factors estimated from experimental results.
Hong Bing Zhu - One of the best experts on this subject based on the ideXlab platform.
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calculation methods for equivalent Fatigue Stress amplitude based on corten dolan accumulative damage rule
Advanced Materials Research, 2010Co-Authors: Hong Bing ZhuAbstract:Structures often enduring random amplitude load or multilevel amplitude load. However, the test researches on Fatigue often using equivalent amplitude load. It is very important for Fatigue research that how to accurately evaluate structure’s Fatigue properties of random amplitude load or multilevel amplitude load when only using equivalent amplitude load Fatigue test results. According to damaging degree equivalent principle of multilevel amplitude load or random amplitude load, deduced equivalent Stress amplitude calculation formula using linearity Miner accumulative damage rule and Corten-Dolan accumulative damage rule. Introduced the formula’s using method on Fatigue detail or Fatigue life evaluation. Utilizing the S-N curve and S-N equation from RC beams Fatigue experiment, verified the formula aiming at 3 RC beams’ random amplitude Fatigue experiment results, and it is indicated that the formula’s results had quite high precision and approached the experimentation result though it is partial security. The formula operated convenience and it had higher precision compared to similar formula, so the formula suit for engineering application.
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calculation method of equivalent Fatigue Stress range based on corten dolan accumulative damage rule
Journal of Highway and Transportation Research and Development, 2010Co-Authors: Hong Bing Zhu, Lizhong JiangAbstract:According to damaging degree equivalent principle of multilevel amplitude load or random amplitude load,the calculation formula of equivalent Fatigue Stress amplitude range was derived by using linear Miner accumulative damage rule and Corten-Dolan accumulative damage rule.The method of applying the formula to Fatigue detail or Fatigue life evaluations was introduced.By utilizing the S-N curve and S-N equation from RC beams Fatigue experiment,the formula and the method were verified based on the random amplitude Fatigue experiment result of 3 RC beams.It is indicated that the calculation result of the formula is of higher precision and it approaches the experimental result though it is partial security.The formula is convenience and suitable for engineering application.
Yong Yang - One of the best experts on this subject based on the ideXlab platform.
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prediction of Fatigue Stress concentration factor using extreme learning machine
Computational Materials Science, 2016Co-Authors: Baoxian Wang, Guangyuan Zhang, Yanliang Du, Weigang Zhao, Yong YangAbstract:Abstract Fatigue Stress concentration factor (FSCF) plays a vital role in studying the limitation of material Fatigue resistance. Theoretically, FSCF not only reflects the level of Fatigue Stress concentration but also indicates the notch sensitive degree. In this work, a novel and efficient numerical model is presented for predicting FSCF, which exploits an emergent learning technique, i.e., Extreme Learning Machine (ELM). Specifically, we adopt seven parameters (i.e., tensile strength, yield strength, Fatigue strength, theoretical Stress concentration factor, notch root radius, samples size and notch Fatigue limit) as the inputs, and the corresponding FSCF value is used as the output. With the randomly generated hidden neuron parameters, the ELM-based predictor can be fast trained. Besides, a pairwise metric constraint is introduced in the presented model, which can elevate the forecasting accuracy. A series of cross validation experiments demonstrate that the proposed FSCF predictor performs favorably against the existing empirical formulas and other learning based methods.
Michael R Hill - One of the best experts on this subject based on the ideXlab platform.
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the effects of laser peening and shot peening on fretting Fatigue in ti 6al 4v coupons
Tribology International, 2009Co-Authors: Michael R HillAbstract:Abstract This paper describes testing of Ti–6Al–4V coupons in fretting Fatigue and compares the effects of mechanical surface treatments on performance. Fretting Fatigue tests were performed using a proving ring for fretting load, bridge-type fretting pads, and applied tension–tension cyclic Fatigue Stress. As-machined (AM), shot peened (SP), and laser peened (LP) coupons were evaluated, and data generated to compare residual Stress, surface condition, lifetime, and fractographic detail encountered for each. Near-surface residual Stress in SP and LP coupons was similar. The layer of compressive residual Stress was far deeper in LP coupons than in SP coupons and, consequently, subsurface tensile residual Stress was significantly greater in LP coupons than in SP coupons. SP coupons exhibited a rough surface and had the greatest volume of fretting-induced wear. LP coupons exhibited a wavy surface and had a small volume of wear localized at wave peaks. SP coupons had the greatest fretting Fatigue lifetime, with significant improvement over AM coupons. Lifetimes of LP coupons were similar to those for SP coupons at high Fatigue Stress, but fell between AM and SP coupons at lower Fatigue Stress. Fractographic evaluation showed that fractures of AM samples were preceded by initiation of fretting-induced cracks, transition of a lead fretting crack to mode-I Fatigue crack growth, and crack growth to failure. SP and LP samples exhibited behavior similar to AM samples at high Fatigue Stress, but in coupons tested at low Stress the lead crack initiated subsurface, near the measured depth of maximum tensile residual Stress, despite the presence of fretting-induced cracks. The level of Fatigue Stress above which lead cracks were initiated by fretting was higher for LP than for SP, and was predicted with good accuracy using an analysis based on linear elastic fracture mechanics, the Fatigue crack growth threshold Stress intensity factor range, and superposition of measured residual Stress and applied Fatigue Stress.
