Finite Element Modeling of a Tennis Racket with Variable String Patterns and Tensions

1990 ◽  
Vol 6 (1) ◽  
pp. 78-91 ◽  
Author(s):  
Mary Ann Bitz Widing ◽  
Manssour H. Moeinzadeh

Finite element techniques were applied in a model of a tennis racket. Linear curved elements were used on the frame of the racket. Nonlinear cable elements were used on the strings. The model allows changing material properties and frame geometry, as do traditional models. Unlike traditional models, however, this model has the flexibility to change the string pattern and string tensions, as the strings are modeled discretely. Sample runs revealed information on the relationship between racket parameters and racket behavior such as deformations, stresses, and reaction forces. The results of the model showed that increasing string tension decreases racket deformation as string tension stiffens the racket. Increased string tension also decreases maximum hand reaction forces but increases stresses.

2018 ◽  
Vol 8 (11) ◽  
pp. 2256 ◽  
Author(s):  
Joshua Fortin-Smith ◽  
James Sherwood ◽  
Patrick Drane ◽  
David Kretschmann

To assist in developing a database of wood material properties for the finite element modeling of wood baseball bats, Charpy impact testing at strain rates comparable to those that a wood bat experiences during a bat/ball collision is completed to characterize the failure energy and strain-to-failure as a function of density and slope-of-grain (SoG) for northern white ash (Fraxinus americana) and sugar maple (Acer saccharum). Un-notched Charpy test specimens made from billets of ash and maple that span the range of densities and SoGs that are approved for making professional baseball bats are impacted on either the edge grain or face grain. High-speed video is used to capture each test event and image analysis techniques are used to determine the strain-to-failure for each test. Strain-to-failure as a function of density relations are derived and these relations are used to calculate inputs to the *MAT_WOOD (Material Model 143) and *MAT_EROSION material options in LS-DYNA for the subsequent finite element modeling of the ash and maple Charpy Impact tests and for a maple bat/ball impact. The Charpy test data show that the strain-to-failure increases with increasing density for maple but the strain-to-failure remains essentially constant over the range of densities considered in this study for ash. The flat response of the ash data suggests that ash-bat durability is less sensitive to wood density than maple-bat durability. The available SoG results suggest that density has a greater effect on the impact failure properties of the wood than SoG. However, once the wood begins to fracture, SoG plays a large role in the direction of crack propagation of the wood, thereby determining if the shape of the pieces breaking away from the bat are fairly blunt or spear-like. The finite element modeling results for the Charpy and bat/ball impacts show good correlation with the experimental data.


2004 ◽  
Vol 841 ◽  
Author(s):  
Yang-Tse Cheng ◽  
Che-Min Cheng

ABSTRACTUsing analytical and finite element modeling, we study conical indentation in linear viscoelastic solids and examine the relationship between initial unloading slope, contact depth, and viscoelastic properties. We will then discuss whether the Oliver-Pharr method for determining contact depth, originally proposed for indentation in elastic and elastic-plastic solids, is applicable to indentation in viscoelastic solids.


2013 ◽  
Vol 14 (8) ◽  
pp. 1479-1485 ◽  
Author(s):  
Sangbaek Park ◽  
Soo-Won Chae ◽  
Jungsoo Park ◽  
Seung-Ho Han ◽  
Junghwa Hong ◽  
...  

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