Physical mesomechanics: The new possibilities of metal fatigue behavior description

2020 ◽  
Author(s):  
A. A. Shanyavskiy ◽  
A. P. Soldatenkov
Keyword(s):  
Fatigue Behavior ◽  
Metal Fatigue ◽  
Physical Mesomechanics ◽  
Behavior Description

High-frequency metal fatigue: the high-cycle fatigue behavior of ULTIMET® alloy

2001 ◽  
Vol 314 (1-2) ◽  
pp. 162-175 ◽  
Author(s):  
L Jiang ◽  
C.R Brooks ◽  
P.K Liaw ◽  
Hsin Wang ◽  
Claudia J Rawn ◽  
...  
Keyword(s):  
High Frequency ◽  
High Cycle Fatigue ◽  
Fatigue Behavior ◽  
Cycle Fatigue ◽  
Metal Fatigue

scholarly journals Fatigue behavior of Nitinol medical devices under multi-axial non-proportional loads

2019 ◽  
Vol 300 ◽  
pp. 12001
Author(s):  
Francesca Berti ◽  
Pei-Jiang Wang ◽  
Andrea Spagnoli ◽  
Carlo Guala ◽  
Francesco Migliavacca ◽  
...  
Keyword(s):  
Fatigue Behavior ◽  
Axial Loading ◽  
Fatigue Behaviour ◽  
Metal Fatigue ◽  
Axial Loads ◽  
Critical Plane ◽  
Stent Restenosis ◽  
Load Combination ◽  
Numerical Predictions ◽  
Von Mises

Nickel-Titanium alloys (Nitinol) are widely used for biomedical applications. Peripheral stents are almost exclusively composed of Nitinol, as its superelasticity is suited for minimally-invasive insertion and durable effect. After crimping and deployment stents undergo cyclic multi-axial loads imposed by vascular and lower-limb motion (e.g. axial compression, bending, and torsion). This complex mechanical environment could lead to metal fatigue and device fracture, with possible severe consequences (e.g. in-stent restenosis). Standard regulations require experimental verification of stent fatigue behaviour for preclinical assessment, but no exact indications are provided to direct the load combination. Moreover, different fatigue criteria were developed for common metals to predict fatigue endurance, but no criteria were specifically defined for the unique thermo-mechanical properties of Nitinol. This study investigated the role of cyclic multi-axial loading conditions on different stent geometries, looking at how they affect the stress/strain distribution along the device and how different criteria may affect the fatigue prediction (e.g. the standard Von Mises alternate approach and other critical plane approaches). Then, a preliminary experimental fatigue campaign was performed in agreement with the numerical simulations in order to compare the numerical predictions with the experimental results. The result suggest that the critical plane approaches are more reliable than the standard Von Mises criterion.

scholarly journals Influence of Aluminide Coating on Fatigue Behavior of a Nickel Superalloy

1985 ◽  
Author(s):  
Xu Jianping ◽  
Xiong Jiyuan
Keyword(s):  
Surface Roughness ◽  
Fatigue Behavior ◽  
Aluminide Coating ◽  
Alloy System ◽  
Nickel Superalloy ◽  
Metal Fatigue ◽  
Mechanical Fatigue ◽  
Substrate Alloy ◽  
Coating Alloy ◽  
Coating Crack

The influence of the technology and the thickness of an aluminide coating on mechanical fatigue of a nickel-alloy at 700°C has been studied. It was shown that the brittleness and the surface roughness of coating were the basic causes to the earlier rupture of a system. The thicker coating, the more harmful to fatigue performance. The mechanism of influnece of coating on metal fatigue and the possibility to estimate fatigue life of coating/alloy system were also discussed. It is believed that the stress concentration caused by coating crack accelerated substrate alloy to rupture.

Life Extension of Propeller Shafts by Hardfacing Welding

2016 ◽  
Vol 872 ◽  
pp. 62-66 ◽  
Author(s):  
Siva Sitthipong ◽  
Prawit Towatana ◽  
Amnuay Sitticharoenchai ◽  
Chaiyoot Meengam
Keyword(s):  
Service Life ◽  
Arc Welding ◽  
Fatigue Behavior ◽  
Research Result ◽  
Welding Process ◽  
Repair Process ◽  
High Rate ◽  
Machine Component ◽  
Metal Fatigue ◽  
Short Service Life

At present the Cut-stern Kolek Boats of local fishermen at Kaoseng Community on the Coast of Songkhla Lake have a high rate of shaft failure. Consequently, the fishermen have spent lots of money on maintenance program of repairing shafts for a few years. Besides, the repairing cost, each time of the failure also causes water pollution from the leakage of grease. The incomplete transmission of power leads to engine overloading and fuel wasting. The investigation of the high failure rate of propeller shafts which were major machine component in power transmission illustrated the failure in normal fracture caused by the mechanisms of metal fatigue. Using the welding repair by shield metal arc welding process did not give the satisfied outcome because it created the short service life of reused propeller shafts after repairing. This research was aimed to study the metal fatigue behavior of long tail shafts in the Cut-stern Kolek boats and introduce the new method of welding repair process to prolong their service life. The experiment revealed that specimens resulted from the new welding repair process and the conventional one possessed different service life. The new process used the flux core which arc welding can prolong the service life of the shafts of boats more than 1.6 times of using the conventional method which is the electric welding by flux core arc welding. The research result will be extended to fishermen, in order to encourage them to become a part of sustainable inshore fisheries.

THE FATIGUE BEHAVIOR OF FRESHWATER ICE

1987 ◽  
Vol 48 (C1) ◽  
pp. C1-329-C1-335 ◽  
Author(s):  
W. A. NIXON ◽  
R. A. SMITH
Keyword(s):  
Fatigue Behavior ◽  
Freshwater Ice

Calculating Energy Release Rate as a Function of Crack Length Using a Multiple-Step Crack Closure Technique in Tire Finite Element Models

2018 ◽  
Vol 46 (3) ◽  
pp. 130-152
Author(s):  
Dennis S. Kelliher
Keyword(s):  
Finite Element ◽  
Energy Release Rate ◽  
Crack Length ◽  
Energy Release ◽  
Crack Closure ◽  
Release Rate ◽  
Fatigue Behavior ◽  
Three Dimensions ◽  
Quantitative Prediction ◽  
Closure Technique

ABSTRACT When performing predictive durability analyses on tires using finite element methods, it is generally recognized that energy release rate (ERR) is the best measure by which to characterize the fatigue behavior of rubber. By addressing actual cracks in a simulation geometry, ERR provides a more appropriate durability criterion than the strain energy density (SED) of geometries without cracks. If determined as a function of crack length and loading history, and augmented with material crack growth properties, ERR allows for a quantitative prediction of fatigue life. Complications arise, however, from extra steps required to implement the calculation of ERR within the analysis process. This article presents an overview and some details of a method to perform such analyses. The method involves a preprocessing step that automates the creation of a ribbon crack within an axisymmetric-geometry finite element model at a predetermined location. After inflating and expanding to three dimensions to fully load the tire against a surface, full ribbon sections of the crack are then incrementally closed through multiple solution steps, finally achieving complete closure. A postprocessing step is developed to determine ERR as a function of crack length from this enforced crack closure technique. This includes an innovative approach to calculating ERR as the crack length approaches zero.

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