scholarly journals Differences in Anatomy and Kinematics in Asian and Caucasian TKA Patients: Influence on Implant Positioning and Subsequent Loading Conditions in Mobile Bearing Knees

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Allan Maas ◽  
Tae Kyun Kim ◽  
Rolf K. Miehlke ◽  
Thomas Hagen ◽  
Thomas M. Grupp
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Knee Flexion ◽  
Failure Modes ◽  
Mobile Bearing ◽  
Element Model ◽  
Floating Platform ◽  
Implant Positioning ◽  
Roll Back

The objective of our study was to determine the mechanical stress conditions under tibiofemoral loading with an overlay of knee kinematics in deep flexion on two different mobile bearing designs in comparison to in vivo failure modes. This study investigates the seldom but severe complication of fatigue failure of polyethylene components at mobile bearing total knee arthroplasty designs. Assuming a combination of a floor-based lifestyle and tibial malrotation as a possible reason for a higher failure rate in Asian countries we developed a simplified finite element model considering a tibiofemoral roll-back angle of 22° and the range of rotational motion of a clinically established floating platform design (e.motion FP) at a knee flexion angle of 120° in order to compare our results to failure modes found in retrieved implants. Compared to the failure mode observed in the clinical retrievals the locations of the occurring stress maxima as well as the tensile stress distribution show analogies. From our observations, we conclude that the newly introduced finite element model with an overlay of deep knee flexion (lateral roll-back) and considerable internally rotated tibia implant positioning is an appropriate analysis for knee design optimizations and a suitable method to predict clinical failure modes.

A Finite Element Model of a Rotating Platform Total Knee Employing a Nonlinear, Dual-Surface-Contact Formulation

2000 ◽  
Author(s):  
Jason K. Otto ◽  
Thomas D. Brown ◽  
John J. Callaghan
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Mobile Bearing ◽  
Element Model ◽  
Polyethylene Insert ◽  
Rotating Platform ◽  
Mobile Interface ◽  
Surface Contact ◽  
Total Knee

Abstract Mobile bearing total knees avoid the conformity/constraint tradeoff of fixed bearing total knees. However, a recent in vivo fluoroscopic study of the most popular mobile bearing total knee in the U.S. showed that bearing motion failed to occur in half of the patients observed. A nonlinear, multiple-surface contact finite element model of a rotating platform total knee was therefore developed to investigate the interaction at the “mobile” interface (contact between the tibial tray and the polyethylene insert) under physiologically relevant loads (1–4 BW) and rotations (10° endorotation). The data showed that there was a linear relationship between axial load and the torque resisting endorotation. Peak contact stresses were located on the medial and lateral peripheral edges of the polyethylene insert. All relative rotation occurred at the “mobile” interface. The same trends were seen in a complementary experimental study of the same components, suggesting that the finite element model is valid under these loading conditions.

Research on seismic behavior of special-shaped CFST column to H-section steel beam joint

2021 ◽  
pp. 136943322110073
Author(s):  
Yu Cheng ◽  
Yuanlong Yang ◽  
Binyang Li ◽  
Jiepeng Liu
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Seismic Behavior ◽  
Failure Modes ◽  
Joint Stiffness ◽  
Load Ratio ◽  
Element Model ◽  
Steel Tube ◽  
Steel Beam ◽  
Static Test

To investigate the seismic behavior of joint between special-shaped concrete-filled steel tubular (CFST) column and H-section steel beam, a pseudo-static test was carried out on five specimens with scale ratio of 1:2. The investigated factors include stiffening types of steel tube (multi-cell and tensile bar) and connection types (exterior diaphragm and vertical rib). The failure modes, hysteresis curves, skeleton curves, stress distribution, and joint shear deformation of specimens were analyzed to investigate the seismic behaviors of joints. The test results showed the connections of exterior diaphragm and vertical rib have good seismic behavior and can be identified as rigid joint in the frames with bracing system according to Eurocode 3. The joint of special-shaped column with tensile bars have better seismic performance by using through vertical rib connection. Furthermore, a finite element model was established and a parametric analysis with the finite element model was conducted to investigate the influences of following parameters on the joint stiffness: width-to-thickness ratio of column steel tube, beam-to-column linear stiffness ratio, vertical rib dimensions, and axial load ratio of column. Lastly, preliminary design suggestions were proposed.

Thermo-Mechanical Analysis of Instrumentation Guide Tube Failure During a Severe Accident in a Nordic Boiling Water Reactor

2020 ◽  
Author(s):  
Ying Yue ◽  
Walter Villanueva ◽  
Hongdi Wang ◽  
Dingqu Wang
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Failure Modes ◽  
Element Model ◽  
Boiling Water ◽  
Severe Accident ◽  
Boiling Water Reactor ◽  
Guide Tube ◽  
Water Reactor ◽  
Water Reactors

Abstract Vessel penetrations are important features of both pressurized water reactors and boiling water reactors. The thermal and structural behaviour of instrumentation guide tubes (IGTs) and control rod guide tubes (CRGTs) during a severe accident is vital in the assessment of the structure integrity of the reactor pressure vessel. Penetrations may fail due to welding failure, nozzle rupture, melt-through, etc. It is thus important to assess the failure mechanisms of penetrations with sufficient details. The objective of this paper is to assess the timing and failure modes of IGTs at the lower head during a severe accident in a Nordic boiling water reactor. In this study, a three-dimensional local finite element model was established using Ansys Mechanical that includes the vessel wall, the nozzle, and the weld joint. The thermo-mechanical loads of the finite element model were based on MELCOR results of a station blackout accident (SBO) combined with a large-break loss-of-coolant accident (LBLOCA) including an external vessel cooling by water as a severe accident management strategy. Given the temperature, creep strain, elastic strain, plastic strain, stress and displacement from the ANSYS simulations, the results showed the timing and failure modes of IGTs. Failure of the IGT penetration by nozzle creep is found to be the dominant failure mode of the vessel. However, it was also found that the IGT is clamped by the flow limiter before the nozzle creep, which means that IGT ejection is unlikely.

scholarly journals Combining Models to Simulate the Condition of the PVC Distribution Network

Proceedings ◽  
2018 ◽  
Vol 2 (11) ◽  
pp. 591
Author(s):  
Karel A. van Laarhoven ◽  
Bas A. Wols
Keyword(s):  
Finite Element ◽  
Drinking Water ◽  
Finite Element Model ◽  
Failure Modes ◽  
Element Model ◽  
Angular Deflection ◽  
Soil Settlement ◽  
Overall Performance ◽  
Water Companies ◽  
Maintenance And Inspection

The failure of joints plays an important role in the overall performance of mains. One of the prevalent failure modes at polyvinyl chloride (PVC) joints is the rupture of pipe or joint, which may occur due to high angular deflection of the pipe with respect to the joint, caused by differential soil settlement. The present paper reports the construction and use of a finite element model to determine the maximum angular deflection of a variety of PVC joints in different loading situations. The resulting acceptable deflections vary between 3° and 8° per side, which differs significantly from installation guidelines. The results will support drinking water companies in substantiating the prioritization of maintenance and inspection.

Personalized finite element model of the knee joint in vivo

2006 ◽  
Vol 39 ◽  
pp. S501
Author(s):  
M. Sangeux ◽  
F. Marin ◽  
F. Charleux ◽  
L. Dürselen ◽  
M.-C. Ho Ba Thoa
Keyword(s):  
Finite Element ◽  
Knee Joint ◽  
Finite Element Model ◽  
Element Model

scholarly journals Engineering our Favorite Pastime

2010 ◽  
Vol 132 (04) ◽  
pp. 44-48
Author(s):  
Lloyd Smith ◽  
James Sherwood
Keyword(s):  
Plastic Deformation ◽  
Finite Element ◽  
Finite Element Model ◽  
Failure Modes ◽  
Element Model ◽  
Layer By Layer ◽  
Ball Impact ◽  
Support Mechanism ◽  
Bat Performance ◽  
Technology Advances

This article describes the equipment and technology advances in baseball and softball games. Research efforts are currently being pursued by the authors to develop a layer-by-layer finite element model of a baseball. While work on improved ball models is ongoing, a number of significant accomplishments have been made with current models. These include comparing bat performance, describing the plastic deformation (denting) observed in metal bats, and the failure modes observed with wood bats. To simulate the bat/ball impact at game-like speeds, a durability machine is used to fire balls at a bat at speeds up to 200 mph, at the rate of 10 per minute. After a ball is shot, it falls into a trough and is loaded back into the magazine, which holds up to 36 balls. The bat-support mechanism simulates the grip and flexibility of a batter and can be programmed to rotate the bat between hits to simulate the use of hollow bats or to remain “label up” as is needed for wood bats.

Sign in / Sign up

Export Citation Format

Share Document