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Modeling of time-dependent force response of fingertip to dynamic loading.

Authors
Wu-JZ; Dong-RG; Smutz-WP; Schopper-AW
Source
J Biomech 2003 Mar; 36(3):383-392
NIOSHTIC No.
20022657
Abstract
An extended exposure to repeated loading on fingertip has been associated to many vascular, sensorineural, and musculoskeletal disorders in the fingers, such as carpal tunnel syndrome, hand-arm vibration syndrome, and flexor tenosynovitis. A better understanding of the pathomechanics of these sensorineural and vascular diseases in fingers requires a formulation of a biomechanical model of the fingertips and analyses to predict the mechanical responses of the soft tissues to dynamic loading. In the present study, a model based on finite element techniques has been developed to simulate the mechanical responses of the fingertips to dynamic loading. The proposed model is two-dimensional and incorporates the essential anatomical structures of a finger: skin, subcutaneous tissue, bone, and nail. The skin tissue is assumed to be hyperelastic and viscoelastic. The subcutaneous tissue was considered to be a nonlinear, biphasic material composed of a hyperelastic solid and an invicid fluid, while its hydraulic permeability was considered to be deformation dependent. Two series of numerical tests were performed using the proposed finger tip model to: (a) simulate the responses of the fingertip to repeated loading, where the contact plate was assumed to be fixed, and the bone within the fingertip was subjected to a prescribed sinusoidal displacement in vertical direction; (b) simulate the force response of the fingertip in a single keystroke, where the keyboard was composed of a hard plastic keycap, a rigid support block, and a nonlinear spring. The time-dependent behavior of the fingertip under dynamic loading was derived. The model predictions of the time-histories of force response of the fingertip and the phenomenon of fingertip separation from the contacting plate during cyclic loading agree well with the reported experimental observations.
Keywords
Models; Musculoskeletal-system; Musculoskeletal-system-disorders; Carpal-tunnel-syndrome; Hand-injuries; Arm-injuries; Mechanical-tests; Cardiovascular-system-disorders; Cumulative-trauma-disorders; Cumulative-trauma; Vibration-disease
Contact
E&CTB/HELD, National Institute for Occupational Safety and Health, Center for Disease Control and Prevention, 1095 Willowdale Road, Morgantown, WV 26505, USA
CODEN
JBMCBS
Publication Date
20030301
Document Type
Journal Article
Email Address
jwu@cdc.gov
Fiscal Year
2003
NTIS Accession No.
NTIS Price
Issue of Publication
3
ISSN
0021-9290
NIOSH Division
HELD
Priority Area
Disease and Injury: Musculoskeletal Disorders of the Upper Extremities
Source Name
Journal of Biomechanics
State
WV
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