Predicting fatigue life of a PMMA based knee spacer using a multiaxial fatigue criterion

2011 ◽  
Vol 9 (3) ◽  
pp. 185-192 ◽  
Author(s):  
Davide Carnelli ◽  
Tomaso Villa ◽  
Dario Gastaldi ◽  
Giancarlo Pennati
Keyword(s):  
Fatigue Life ◽  
Multiaxial Fatigue ◽  
Fatigue Criterion

A computational approach based on a multiaxial fatigue criterion combining phase transformation and shakedown response for the fatigue life assessment of Nitinol stents

2018 ◽  
Vol 29 (19) ◽  
pp. 3710-3724 ◽  
Author(s):  
Giulia Scalet ◽  
Costantino Menna ◽  
Andrei Constantinescu ◽  
Ferdinando Auricchio
Keyword(s):  
Phase Transformation ◽  
Fatigue Life ◽  
Computational Design ◽  
Phase Evolution ◽  
Multiaxial Fatigue ◽  
Life Assessment ◽  
Patient Specific ◽  
Element Analysis ◽  
Nitinol Stents ◽  
Fatigue Criterion

Self-expanding stents made of Nitinol, a Nickel–Titanium shape memory alloy, are used in standard medical implants for the treatment of cardiovascular diseases. Despite the increasing success, clinical studies have reported stent failure after the deployment in the human body, thus undermining patient’s safety and life. This study aims to fill the gap of reliable assessment of the fatigue life of Nitinol stents. We propose a global computational design method for preclinical validation of Nitinol stents, which can be extended to patient-specific computations. The proposed methodology is composed of a mechanical finite element analysis and a fatigue analysis. The latter analysis is based on a novel multiaxial fatigue criterion of the Dang Van type, combining the shakedown response of the stent and the complexity of phase transformation taking place within the material. The method is implemented in the case of a carotid artery stent. The implant configuration as well as the applied cyclic loading are shown to affect material phase evolution as well as stent lifetime. The comparison with the results obtained by applying a strain-based constant-life diagram approach allows to critically discuss both fatigue criteria and to provide useful recommendations about their applicability.

Estimation of Fatigue Life for Hydraulic Excavator Boom under All Operating States

2011 ◽  
Vol 199-200 ◽  
pp. 463-469
Author(s):  
Qing Xin Ding ◽  
Ying Cheng Tian ◽  
Juan Chen ◽  
Jian Wen Chen ◽  
Kun Liang Hui ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Estimation Method ◽  
Maximum Principal Stress ◽  
Multiaxial Fatigue ◽  
Hydraulic Excavator ◽  
Dangerous Zone ◽  
Support Force ◽  
Contrast Analysis ◽  
History Of ◽  
Hinged Support

Fatigue is one of the most common failure mode in hydraulic excavator boom. To find the most fatigue dangerous operating state of boom and effectively improve the life of the structure, a new method is proposed for the estimation of fatigue life under all operation states. In the case of unknown the history of loading, firstly find out the hinged support force under all boom poses, then calculate the stress of every point of the boom under the actions of each group hinged support force via finite element method, and finally simulate all operating states through the poses combination, conducts analysis of multiaxial fatigue life in the maximum principal stress as the nominal stress, calculates the life and the most dangerous operating state in all points, and compares to obtain the most dangerous position and the life of the boom. The results of contrast analysis showed that: the most dangerous zone of the excavator boom calculated by the life estimation method of all operating states coincide with the actual destruction situation. The life of the structure can be greatly improved after a simple reasonable improvement of the parts.

scholarly journals Multiaxial fatigue study on steel transversal attachments under constant amplitude proportional and non-proportional loadings

2018 ◽  
Vol 165 ◽  
pp. 16007
Author(s):  
Martin Garcia ◽  
Claudio A. Pereira Baptista ◽  
Alain Nussbaumer
Keyword(s):  
Fatigue Life ◽  
High Strength ◽  
Fatigue Tests ◽  
Multiaxial Fatigue ◽  
Life Assessment ◽  
Experimental Program ◽  
Proportional Loading ◽  
Load Carrying ◽  
Stress States ◽  
Experimental Values

In this study, the multiaxial fatigue strength of full-scale transversal attachment is assessed and compared to original experimental results and others found in the literature. Mild strength S235JR steel is used and an exploratory investigation on the use of high strength S690QL steel and the effect of non-proportional loading is presented. The study focuses on non-load carrying fillet welds as commonly used in bridge design and more generally between main girders and struts. The experimental program includes 33 uniaxial and multiaxial fatigue tests and was partially carried out on a new multiaxial setup that allows proportional and non-proportional tests in a typical welded detail. The fatigue life is then compared with estimations obtained from local approaches with the help of 3D finite element models. The multiaxial fatigue life assessment with some of the well-known local approaches is shown to be suited to the analysis under multiaxial stress states. The accuracy of each models and approaches is compared to the experimental values considering all the previously cited parameters.

scholarly journals Multiaxial fatigue criterion based on parameters from torsion and axial S-N curve

2016 ◽  
Vol 10 (37) ◽  
pp. 146-152 ◽  
Author(s):  
M. Margetin ◽  
R. Durka ◽  
V. Chmelko
Keyword(s):  
Multiaxial Fatigue ◽  
Fatigue Criterion
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