Concept and Modeling of a Statically Balanced Compliant Laparoscopic Grasper

2009 ◽  
Author(s):  
Nima Tolou ◽  
Just L. Herder
Keyword(s):  
Finite Element ◽  
Finite Element Modeling ◽  
Force Feedback ◽  
Negative Stiffness ◽  
Optimized Design ◽  
Compensation Mechanism ◽  
Linear Elastic Material ◽  
Element Modeling ◽  
Linear Elastic ◽  
Laparoscopic Grasper

The objective of this investigation is to present a concept as well as mathematical modeling and finite element modeling of a statically balanced compliant laparoscopic grasper. To obtain force feedback, the positive stiffness of the compliant grasper was statically balanced by a negative-stiffness compensation mechanism. The negative stiffness has been produced by pairs of pre-stressed initially-curved pinned-pinned beams out of linear elastic material, arranged perpendicular to the link driving the grasper. First, the conceptual design is explained. Subsequently, its behavior is mathematically formulated and then finite element modeling is implemented using a commercially available finite element modeling package. Finally, a stress-optimized design of a negative-stiffness compensation mechanism and the effect of parameter changes on the accuracy are obtained. The results illustrate the efficiency of the applied analysis methods for the case of statically balancing the laparoscopic grasper. It also demonstrates the efficiency of the balancer concept. The proposed procedure is found to be convenient for this set of problems, and can probably be applied to other similar practical problems.

Comparison between isotropic linear-elastic law and isotropic hyperelastic law in the finite element modeling of the brachial plexus

2017 ◽  
Vol 62 (6) ◽  
pp. 664-668 ◽  
Author(s):  
A. Perruisseau-Carrier ◽  
N. Bahlouli ◽  
G. Bierry ◽  
P. Vernet ◽  
S. Facca ◽  
...  
Keyword(s):  
Finite Element ◽  
Finite Element Modeling ◽  
Brachial Plexus ◽  
Element Modeling ◽  
Linear Elastic

Towards the Design of a Statically Balanced Compliant Laparoscopic Grasper Using Topology Optimization

2008 ◽  
Author(s):  
Ditske J. B. A. de Lange ◽  
Matthijs Langelaar ◽  
Just L. Herder
Keyword(s):  
Topology Optimization ◽  
Force Feedback ◽  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Negative Stiffness ◽  
Compensation Mechanism ◽  
Laparoscopic Grasper ◽  
The Difference ◽  
Force Displacement ◽  
Compliant Mechanism Design

This paper presents the design of a grasping instrument for minimally invasive surgery. Due to its small dimensions a compliant mechanism seems promising. To obtain force feedback, the positive stiffness of the compliant grasper must be statically balanced by a negative-stiffness compensation mechanism. For the design of compliant mechanisms, topology optimization can be used. The goal of this paper is to investigate the applicability of topology optimization to the design of a compliant laparoscopic grasper and particularly a compliant negative-stiffness compensation mechanism. In this study, the problem is subdivided in the grasper part and the compensation part. In the grasper part the deflection at the tip of the grasper is optimized. This results in a design that has a virtually linear force-displacement characteristic that forms the input for the compensation part. In the compensation part the difference between the force-displacement characteristic of the grasper part and the characteristic of the compensation part is minimized. An optimization problem is formulated enabling a pre-stress to be incorporated, which is required to obtain the negative stiffness in the compensation part. We can conclude that topology optimization is a promising approach in the field of statically balanced compliant mechanism design, even though there is great scope improvement of the method.

Exact First Order Finite Element Modeling for Eddy Current NDE

1991 ◽  
Vol 3 (1) ◽  
pp. 235-253 ◽  
Author(s):  
L. D. Philipp ◽  
Q. H. Nguyen ◽  
D. D. Derkacht ◽  
D. J. Lynch ◽  
A. Mahmood
Keyword(s):  
Finite Element ◽  
Finite Element Modeling ◽  
Eddy Current ◽  
Element Modeling ◽  
First Order ◽  
Eddy Current Nde

Tire Vibration Modes and Effects on Vehicle Ride Quality

1993 ◽  
Vol 21 (1) ◽  
pp. 23-39 ◽  
Author(s):  
R. W. Scavuzzo ◽  
T. R. Richards ◽  
L. T. Charek
Keyword(s):  
Finite Element ◽  
Finite Element Modeling ◽  
Operating Conditions ◽  
Modal Testing ◽  
Ride Quality ◽  
Vibration Modes ◽  
Inflation Pressure ◽  
Passenger Cars ◽  
Element Modeling ◽  
Road Surfaces

Abstract Tire vibration modes are known to play a key role in vehicle ride, for applications ranging from passenger cars to earthmover equipment. Inputs to the tire such as discrete impacts (harshness), rough road surfaces, tire nonuniformities, and tread patterns can potentially excite tire vibration modes. Many parameters affect the frequency of tire vibration modes: tire size, tire construction, inflation pressure, and operating conditions such as speed, load, and temperature. This paper discusses the influence of these parameters on tire vibration modes and describes how these tire modes influence vehicle ride quality. Results from both finite element modeling and modal testing are discussed.

Evolving the Banded Radial Tire

1987 ◽  
Vol 15 (1) ◽  
pp. 30-41 ◽  
Author(s):  
E. G. Markow
Keyword(s):  
Finite Element ◽  
Wear Rate ◽  
Finite Element Modeling ◽  
Laboratory Tests ◽  
Rolling Resistance ◽  
Two Dimensional ◽  
Theoretical Discussion ◽  
Radial Tire ◽  
Puncture Resistance ◽  
Element Modeling

Abstract Development of the banded radial tire is discussed. A major contribution of this tire design is a reliable run-flat capability over distances exceeding 160 km (100 mi). Experimental tire designs and materials are considered; a brief theoretical discussion of the mechanics of operation is given based on initial two-dimensional studies and later on more complete finite element modeling. Results of laboratory tests for cornering, rolling resistance, and braking are presented. Low rolling resistance, good cornering and braking properties, and low tread wear rate along with good puncture resistance are among the advantages of the banded radial tire designs.

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