Design and Manufacturing of Drug Eluting Depot Stents with Micro-Sized Drug Reservoirs

2013 ◽  
Vol 479-480 ◽  
pp. 225-229
Author(s):  
Hao Ming Hsiao ◽  
Chun Ting Yeh ◽  
Tsung Yuan Wu ◽  
Li Wei Wu ◽  
Bor Hann Huang ◽  
...  
Keyword(s):  
Finite Element ◽  
Fatigue Life ◽  
Fatigue Resistance ◽  
Finite Element Models ◽  
Mechanical Integrity ◽  
Design And Manufacturing ◽  
Radial Strength ◽  
Drug Eluting ◽  
Through Hole

The effects of micro-sized through-hole drug reservoirs on several key clinical attributes of the drug eluting depot stent were investigated. Finite element models were developed to predict the mechanical integrity of a balloon-expandable stent at various stages such as manufacturing and deployment, as well as the stent radial strength and fatigue life. Results show that (1) creating drug reservoirs on a stent could impact the stent fatigue resistance to certain degrees, and (2) drug reservoirs on the stent crowns led to much greater loss in all key clinical attributes than reservoirs on other locations. Based on these findings, an optimized depot stent was proposed/manufactured and proven to be a feasible design.

Structural-transport finite element models of drug eluting stents in large arteries

2006 ◽  
Vol 39 ◽  
pp. S400
Author(s):  
B. Simon ◽  
J. Vande Geest ◽  
P. Rigby ◽  
T. Newberg ◽  
S. Williams ◽  
...  
Keyword(s):  
Finite Element ◽  
Drug Eluting Stents ◽  
Finite Element Models ◽  
Large Arteries ◽  
Drug Eluting

Fatigue Life of Seamless Steel Pressure Vessels

1987 ◽  
Vol 109 (3) ◽  
pp. 323-328
Author(s):  
R. L. Brockenbrough
Keyword(s):  
Finite Element ◽  
Fatigue Life ◽  
Fracture Mechanics ◽  
Strain Gage ◽  
Fatigue Tests ◽  
Pressure Vessels ◽  
Finite Element Models ◽  
Conservative Estimate ◽  
Cyclic Pressure ◽  
Seamless Steel

Cyclic-pressure fatigue tests of three seamless steel pressure vessels show that typical production vessels should have a fatigue life at least equal to the allowable life calculated by code procedures. Stresses from finite-element models and strain-gage measurements are correlated and used in a simplified fracture mechanics approach for a conservative estimate of fatigue life.

Fatigue Life Calculation of the in-Service Dented Pipeline

2011 ◽  
Vol 467-469 ◽  
pp. 1327-1332 ◽  
Author(s):  
Wu Ying ◽  
Peng Zhang ◽  
Wu Liu
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Fatigue Life ◽  
Pressure Variation ◽  
Finite Element Models ◽  
Test Results ◽  
Peak Period ◽  
Factors Affecting ◽  
Life Model ◽  
Calculation Results

Dent is one of the important factors affecting pipeline fatigue life, and it will greatly reduce the fatigue life of the pipeline in service. Based on a large number of foreign dented pipeline fatigue test results and fatigue life model, for the typical dent defect, using finite element method, various parameters are changed and finite element models are obtained under different conditions. According to many calculation results, a key ratio of peak period stress and pipeline pressure variation are obtained, which are substituted to the fatigue life model and the example are calculated.

scholarly journals PDLLA-Zn-nitrided Fe bioresorbable scaffold with 53-μm-thick metallic struts and tunable multistage biodegradation function

2021 ◽  
Vol 7 (23) ◽  
pp. eabf0614
Author(s):  
Danni Shen ◽  
Haiping Qi ◽  
Wenjiao Lin ◽  
Wanqian Zhang ◽  
Dong Bian ◽  
...  
Keyword(s):  
Sacrificial Layer ◽  
Drug Eluting Stents ◽  
Subsequent Stage ◽  
Bioresorbable Scaffold ◽  
Strut Thickness ◽  
Mechanical Integrity ◽  
Initial Stage ◽  
Radial Strength ◽  
Drug Eluting ◽  
Drug Coating

Balancing the biodegradability and mechanical integrity of a bioresorbable scaffold (BRS) with time after implantation to match the remodeling of the scaffolded blood vessel is important, but a key challenge in doing so remains. This study presents a novel intercalated structure of a metallic BRS by introducing a nanoscale Zn sacrificial layer between the nitrided Fe platform and the sirolimus-carrying poly(d,l-lactide) drug coating. The PDLLA-Zn-FeN BRS shows a multistage biodegradation behavior, maintaining mechanical integrity at the initial stage and exhibiting accelerated biodegradation at the subsequent stage in both rabbit abdominal aortas and human coronary arteries, where complete biodegradation was observed about 2 years after implantation. The presence of the nanoscale Zn sacrificial layer with an adjustable thickness also contributes to the tunable biodegradation of BRS and allows the reduction of the metallic strut thickness to 53 μm, with radial strength as strong as that of the current permanent drug-eluting stents.

scholarly journals Finite Element Study on Continuous Rotating versus Reciprocating Nickel-Titanium Instruments

2016 ◽  
Vol 27 (4) ◽  
pp. 436-441 ◽  
Author(s):  
Mohamed I. El-Anwar ◽  
Salah A. Yousief ◽  
Engy M. Kataia ◽  
Tarek M. Abd El-Wahab
Keyword(s):  
Finite Element ◽  
Low Cost ◽  
Nickel Titanium ◽  
Finite Element Models ◽  
Element Analysis ◽  
Cross Sectional ◽  
Design And Manufacturing ◽  
Cad Cam ◽  
Strain Stress ◽  
Sectional Shape

Abstract In the present study, GTX and ProTaper as continuous rotating endodontic files were numerically compared with WaveOne reciprocating file using finite element analysis, aiming at having a low cost, accurate/trustworthy comparison as well as finding out the effect of instrument design and manufacturing material on its lifespan. Two 3D finite element models were especially prepared for this comparison. Commercial engineering CAD/CAM package was used to model full detailed flute geometries of the instruments. Multi-linear materials were defined in analysis by using real strain-stress data of NiTi and M-Wire. Non-linear static analysis was performed to simulate the instrument inside root canal at a 45° angle in the apical portion and subjected to 0.3 N.cm torsion. The three simulations in this study showed that M-Wire is slightly more resistant to failure than conventional NiTi. On the other hand, both materials are fairly similar in case of severe locking conditions. For the same instrument geometry, M-Wire instruments may have longer lifespan than the conventional NiTi ones. In case of severe locking conditions both materials will fail similarly. Larger cross sectional area (function of instrument taper) resisted better to failure than the smaller ones, while the cross sectional shape and its cutting angles could affect instrument cutting efficiency.

Analysis of Fatigue Life of SPR (Self-Piercing Riveting) Jointed Various Specimens Using FEM

2008 ◽  
Vol 580-582 ◽  
pp. 617-620 ◽  
Author(s):  
Bok Kyu Lim
Keyword(s):  
Finite Element ◽  
Fatigue Life ◽  
Fatigue Behavior ◽  
Pure Shear ◽  
Automotive Application ◽  
Finite Element Models ◽  
Tensile Shear ◽  
Element Analysis ◽  
Shear Specimen ◽  
Cross Tension

Self-Piercing Riveting(SPR) is becoming an important joining technique for various material sheets and shapes, of automotive application. Fatigue behavior of SPR connections needs to be investigated experimentally and numerically to predict SPR fatigue lives. The simulations of various SPR specimens (Coach-Peel specimen, Cross-Tension specimen, Tensile-Shear specimen, Pure-Shear specimen) are performed to predict the fatigue life of SPR connections under different shape combinations. Finite element models of various SPR specimens are developed using a FEMFAT SPOT SPR pre-processor. The fatigue lives of SPR specimens are predicted using a FEMFAT 4.4e based on the linear finite element analysis.

scholarly journals METHODS DEVELOPMENT OF STRENGTH AND RELIABILITY ANALYSIS OF ROLLING-STOCK BEARING STRUCTURE USING MATHEMATICAL MODELING METHODS

2020 ◽  
Vol 2020 (3) ◽  
pp. 29-37
Author(s):  
Vladimir Kobishchanov ◽  
Dmitriy Antipin ◽  
Dmitriy Rasin ◽  
Marina Manueva
Keyword(s):  
Mathematical Modeling ◽  
Finite Element ◽  
Fatigue Life ◽  
Strain State ◽  
Rolling Stock ◽  
Finite Element Models ◽  
Stress Strain ◽  
Stress Strain State ◽  
Bearing Structure ◽  
Pivot Joint

The purpose of the work is a procedure formation for the analysis of strength and reliability of rolling-stock bearing structure using methods of mathematical modeling. Its appraisal is shown by the example of improvements in a universal gondola car bearing structure. The procedure offered is formed by a mathematical modeling of bearing structure dynamic loading in the rolling-stock operation including shunting movement encounters. At the first stage of the procedure the dynamic computer simulations of a rail crew movement on way roughness are under development. As a result of modeling there are defined dynamic loads influencing a bearing structure in operation. The analysis of the stress-strain state of the bearing structure is carried out on the basis of detailed shell finite element models. The computation is carried out in a dynamic position through the method of the direct integration of nodal-relocation equations. The estimate of bearing structures fatigue life in a pivot area was carried out on the basis of the linear hypothesis of fatigue damages summation, the power approximation of a material fatigue curve and scheming dynamic stresses affecting the structure through the method of complete cycles. Within the limits of the procedure the history of loading was presented as a step function. On the basis of the results of a stress-strain state in the bearing structure of a gondola car body in a static and dynamic location there is carried out the analysis of fatigue life in a pivot area of the gondola car and the conclusions were drawn regarding crack-like defect occurrence in a center plate arrangement of a frame. There are offered three versions for updating the pivot joint of a gondola car with the purpose of its fatigue life increase. For each version of updating there are developed corresponding detailed finite element models of the pivot area and on their basis the analysis of strength and fatigue life is performed. On the basis of computation results and taking into account the manufacturability of center plate arrangement production an efficient version is recommended for updating a pivot joint of a gondola car. The pivot joint modernization according to the version offered allowed decreasing maximum acting stresses in the pivot joint by 27% and increasing service life of the welded joint elements up to 29 years.

Fatigue Life Prediction of Spot-Welded Structure under Different Finite Element Models of Spot-Weld

2010 ◽  
Vol 118-120 ◽  
pp. 191-195 ◽  
Author(s):  
Tao Zhu ◽  
Shou Ne Xiao ◽  
Guang Wu Yang ◽  
Bing Rong Miao
Keyword(s):  
Finite Element ◽  
Fatigue Life ◽  
Life Prediction ◽  
Absolute Error ◽  
Spot Weld ◽  
Fatigue Life Prediction ◽  
Finite Element Models ◽  
Beam Model ◽  
Actual Situation ◽  
Weld Fatigue

In order to accurately and conveniently simulate spot-weld in FEA, based on the typical specimen of stainless steel, three typical finite element models (FEM) of spot-welds have been created as analysis objects. Firstly, based on the calculation theory of the spot-weld fatigue, two sets of analytical solution, which were the maximum principle stress of the specimen around the spot-weld nugget, were obtained under the action of stretching and shearing, respectively. Then, their linear elastic FEM were established, and the stress states around the spot-weld nugget and the adjacent sheets were analyzed. Finally, according to the results compared between the analytical solution and simulation solution, it can be seen that, when the specimen was stretched, using the brick model to simulate the nugget can get the smallest absolute error of the principle stress, so its spot-weld fatigue damage is the most consistent with the actual situation, a stiff beam model followed, and an umbrella model is the worst; when the specimen was sheared, using the brick model to simulate the nugget can also get the smallest absolute error of the principle stress, so its spot-weld fatigue damage is also the most consistent with the actual situation, the umbrella model is followed, and the stiff beam model is the worst. The results show that appropriate selection of spot-weld FEM is extremely essential for fatigue life prediction under the initial design of products.

Analysis of Fatigue Life in High Temperature of W Pattern Sealing Rings Used in Aircraft Engine

2014 ◽  
Vol 496-500 ◽  
pp. 571-574
Author(s):  
Xi Chen ◽  
Yun Wang
Keyword(s):  
Finite Element ◽  
High Temperature ◽  
Fatigue Life ◽  
Cyclic Loading ◽  
Fatigue Test ◽  
Aircraft Engine ◽  
Finite Element Models ◽  
Flight Safety ◽  
Sectional Structure ◽  
High Temperature Gas

sealing rings used in aircraft engine are surrounded by high-temperature gas and cyclic loading when they are working. The reliability of its work directly affect flight safety and engines life. This paper framed some kind of W pattern sealing rings finite element models with different sectional structure size, first analyze them strength of structure in specific conditions, then simulate the fatigue life of them by using analysis methods of fatigue and parameters of fatigue test, finally we can get damage contours and fatigue life in high temperature of W pattern sealing rings theoretically, providing some theoretical reference of designing and manufacturing sealing rings.

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