Erratum: “Dynamic Motion Analysis of Plane Mechanisms With Coulomb and Viscous Damping via the Joint Force Analysis” (Journal of Engineering for Industry, 1975, 97, pp. 551–560)

1975 ◽  
Vol 97 (3) ◽  
pp. 1148-1148
Author(s):  
C. Bagci
Keyword(s):  
Motion Analysis ◽  
Viscous Damping ◽  
Force Analysis ◽  
Joint Force ◽  
Dynamic Motion

Dynamic Motion Analysis of Plane Mechanisms With Coulomb and Viscous Damping via the Joint Force Analysis

1975 ◽  
Vol 97 (2) ◽  
pp. 551-560 ◽  
Author(s):  
Cemil Bagci
Keyword(s):  
Dynamic Equilibrium ◽  
Viscous Damping ◽  
Force Analysis ◽  
Initial Value ◽  
Damping Force ◽  
Joint Force ◽  
Coulomb Damping ◽  
Dynamic Motion ◽  
Joint Forces ◽  
Input Torque

Analysis of response of determinate plane mechanisms to known driving input force, or input torque, via the joint force analysis is presented. Coulomb damping and viscous damping forces in the pair bearings are included. Equations of dynamic equilibrium are solved for the components of the normal joint forces and for the motion of the mechanism as initial-value problems. The rotation of the resultant joint force, due to the fact that the pair member on a link is the inner member or the outer member of the pair, is considered by defining a generalized Coulomb damping force. Links of the mechanisms are considered rigid. The plane 4R and slider-crank switch mechanisms are investigated. Explicit solutions and numerical examples are given.

scholarly journals Impact of dynamic alignment, motion, and center of rotation on myelopathy grade and regional disability in cervical spondylotic myelopathy

2015 ◽  
Vol 23 (6) ◽  
pp. 690-700 ◽  
Author(s):  
Shian Liu ◽  
Renaud Lafage ◽  
Justin S. Smith ◽  
Themistocles S. Protopsaltis ◽  
Virginie C. Lafage ◽  
...  
Keyword(s):  
Range Of Motion ◽  
Motion Analysis ◽  
Cervical Spondylotic Myelopathy ◽  
Dynamic Motion ◽  
Sf 36 ◽  
Flexion Extension ◽  
Focal Parameters ◽  
The Mean ◽  
Neck Disability ◽  
Flexion And Extension

OBJECT Cervical stenosis is a defining feature of cervical spondylotic myelopathy (CSM). Matsunaga et al. proposed that elements of stenosis are both static and dynamic, where the dynamic elements magnify the canal deformation of the static state. For the current study, the authors hypothesized that dynamic changes may be associated with myelopathy severity and neck disability. This goal of this study was to present novel methods of dynamic motion analysis in CSM. METHODS A post hoc analysis was performed of a prospective, multicenter database of patients with CSM from the AOSpine North American study. One hundred ten patients (34%) met inclusion criteria, which were symptomatic CSM, age over 18 years, baseline flexion/extension radiographs, and health-related quality of life (HRQOL) questionnaires (modified Japanese Orthopaedic Association [mJOA] score, Neck Disability Index [NDI], the 36-Item Short Form Health Survey Physical Component Score [SF-36 PCS], and Nurick grade). The mean age was 56.9 ± 12 years, and 42% of patients were women (n = 46). Correlations with HRQOL measures were analyzed for regional (cervical lordosis and cervical sagittal vertical axis) and focal parameters (kyphosis and spondylolisthesis between adjacent vertebrae) in flexion and extension. Baseline dynamic parameters (flexion/extension cone relative to a fixed C-7, center of rotation [COR], and range of motion arc relative to the COR) were also analyzed for correlations with HRQOL measures. RESULTS At baseline, the mean HRQOL measures demonstrated disability and the mean radiographic parameters demonstrated sagittal malalignment. Among regional parameters, there was a significant correlation between decreased neck flexion (increased C2–7 angle in flexion) and worse Nurick grade (R = 0.189, p = 0.048), with no significant correlations in extension. Focal parameters, including increased C-7 sagittal translation overT-1 (slip), were significantly correlated with greater myelopathy severity (mJOA score, Flexion R = −0.377, p = 0.003; mJOA score, Extension R = −0.261, p = 0.027). Sagittal slip at C-2 and C-4 also correlated with worse HRQOL measures. Reduced flexion/extension motion cones, a more posterior COR, and smaller range of motion correlated with worse general health SF-36 PCS and Nurick grade. CONCLUSIONS Dynamic motion analysis may play an important role in understanding CSM. Focal parameters demonstrated a significant correlation with worse HRQOL measures, especially increased C-7 sagittal slip in flexion and extension. Novel methods of motion analysis demonstrating reduced motion cones correlated with worse myelopathy grades. More posterior COR and smaller range of motion were both correlated with worse general health scores (SF-36 PCS and Nurick grade). To our knowledge, this is the first study to demonstrate correlation of dynamic motion and listhesis with disability and myelopathy in CSM.

Gross-Motion Dynamic Response Analysis of Indeterminate Mechanisms by Matrix Displacement Method

1975 ◽  
Vol 97 (2) ◽  
pp. 682-688
Author(s):  
R. L. Brasfield ◽  
Cemil Bagci
Keyword(s):  
Dynamic Response ◽  
Response Analysis ◽  
Force Analysis ◽  
Initial Value ◽  
Small Oscillations ◽  
Dynamic Response Analysis ◽  
Joint Force ◽  
Solution Of Equations ◽  
The Matrix ◽  
Space Mechanisms

A method of gross-motion dynamic response analysis of indeterminate space mechanisms, as well as indeterminate plane mechanisms with offsets of links, to specified input forces or torques, such as in mechanisms of automated systems, mechanical robots, and switching mechanisms, is presented. The method uses joint force analysis along with the matrix displacement-direct element method. Unknown motion of the mechanism as function of time is determined by the solution of equations of gross-motion as an initial value problem. The effect of small oscillations of a link about an equilibrium position is neglected. An indeterminate plane four-bar and the indeterminate Bennett mechanisms are analyzed as switching mechanisms in the numerical examples.

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