scholarly journals SIMPLIFIED VERSUS REAL GEOMETRY FINGERTIP MODELS: A FINITE ELEMENT STUDY TO PREDICT FORCE–DISPLACEMENT RESPONSE UNDER FLAT CONTACT COMPRESSION

2018 ◽  
Vol 18 (04) ◽  
pp. 1850048
Author(s):  
JEREMY DALLARD ◽  
SONIA DUPREY ◽  
XAVIER MERLHIOT

Finite element fingertip models are useful tools to assess product ergonomics. While “real geometry” approaches provide accurate results, developing models requires medical images. “Simpified geometry” approaches have to date not been tested to see whether they can provide equally accurate results in terms of mechanical response, i.e. force-displacement response and dimensions of fingertip contact area. Four fingertip models were built either from medical images (Visible Human project) or from simplified geometries. Simulations of fingertip flat contact compression at 20[Formula: see text] were performed. A 2nd order hyperelastic material property was used to effectively reproduce the mechanical behavior of the fingertip. Models based on simplified geometries such as conics proved as accurate as models reconstructed from medical images. However, accurate positioning of the bony phalanx is paramount if a biofidelic mechanical response is to be reproduced.

2020 ◽  
Vol 142 (8) ◽  
Author(s):  
Brett D. Steineman ◽  
Robert F. LaPrade ◽  
Tammy L. Haut Donahue

Abstract Nonanatomic placement of posteromedial meniscal root repairs alters knee mechanics; however, little is known about how the position and magnitude of misplacement affect knee mechanics. Finite element knee models were developed to assess changes in cartilage and meniscus mechanics for anatomic and various nonanatomic repairs with respect to intact. In total, 25 different repair locations were assessed at loads of 500 N and 1000 N. The two-simple-suture method was represented within the models to simulate posteromedial meniscal root repairs. Anatomic repairs nearly restored total contact area; however, meniscal hoop stress decreased, meniscal extrusion increased, and cartilage–cartilage contact area increased. Repairs positioned further posterior altered knee mechanics the most and repairs positioned further anterior restored knee mechanics for posteromedial root repairs. Despite this, repair tension increased with further anterior placement. Anterior placement of repairs results in more restorative contact mechanics than posterior placement; however, anterior placement also increased the risk of suture cut-out or failure following repairs. Anatomic placement of repairs remains the best option because of the risks involved with anterior placement; however, suture methods need to be improved to better restore the strength of repairs to that of the native insertion. Proper placement of repairs is important to consider with meniscal root repairs because misplacement may negatively affect cartilage and meniscus mechanics in patients.


PLoS ONE ◽  
2012 ◽  
Vol 7 (9) ◽  
pp. e41397 ◽  
Author(s):  
Ya-Bo Yan ◽  
Wei Qi ◽  
Zi-Xiang Wu ◽  
Tian-Xia Qiu ◽  
Ee-Chon Teo ◽  
...  

2010 ◽  
Vol 132 (3) ◽  
Author(s):  
L. Li ◽  
I. Etsion ◽  
F. E. Talke

A model for the contact area and static friction of nominally flat rough surfaces and rough spherical surfaces is presented. The model extends previously published models, which are limited to plasticity index values below 8, to higher plasticity index values by accounting for fully plastically deformed asperities based on finite element results by Jackson and Green [2005, “A Finite Element Study of Elasto-Plastic Hemispherical Contact Against a Rigid Flat,” Trans. ASME, J. Tribol., 127, pp. 343–354]. The present model also corrects some deficiencies of the earlier models at very small plasticity index values below 0.5.


Vacuum ◽  
1991 ◽  
Vol 42 (16) ◽  
pp. 1047-1048 ◽  
Author(s):  
HF Wang ◽  
A Wagendristel ◽  
X Yang ◽  
P Torzicky ◽  
H Bangert ◽  
...  

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