Design of a Two Degree-of-Freedom Compliant Tool Tip for a Handheld Powered Surgical Tool

2016 ◽  
Vol 11 (1) ◽  
Author(s):  
Karthik Chandrasekaran ◽  
Asokan Thondiyath
Keyword(s):  
Carrying Capacity ◽  
Compressive Load ◽  
Degree Of Freedom ◽  
Stainless Steel Tube ◽  
Load Carrying Capacity ◽  
Compliant Joints ◽  
Surgical Tool ◽  
Load Carrying ◽  
Command Input ◽  
Two Degree Of Freedom

A novel monobloc design of a two degree-of-freedom (DOF) compliant tool tip for a handheld powered surgical tool is presented in this paper. The monobloc tool tip can pitch and yaw using corner-filleted flexure hinge-based compliant joints and has an integrated compliant grasper. The 2DOF of the tool tip is realized by six compliant joints placed in an alternating fashion, orthogonal to each other. The tool is externally powered and consists of a drive box, a stainless steel tube, and a compliant tool tip at the distal end. The drive box houses a thumb joystick for command input, three servo actuators, and a microcontroller. The microcontroller maps surgeon's command input to the tool tip orientation and grasper actuation. By design, the graspers of the tool tip are actuated by tensile forces conveyed by the tethers, which exert a compressive load on the 2DOF compliant joints. Since the compressive load-carrying capacity of slender flexure-based compliant joints is limited, a design to enhance the compressive load-carrying capacity of the compliant joints with a circular guide is presented. A finite-element simulation was done to verify the design of the compliant joints. Experiments were carried out to assess the relationship between the force input by the servo actuators and joint deflection. Additional experiments were carried out to determine the maximum pinching force that can be exerted by the compliant graspers. A prototype of the complete surgical tool was built to demonstrate the utility of the proposed compliant tool tip as an alternative to traditional tool tip for a handheld powered surgical tool.

PARAMETRIC TRAJECTORY OPTIMISATION FOR INCREASED PAYLOAD

2016 ◽  
Vol 40 (2) ◽  
pp. 125-137 ◽  
Author(s):  
André Gallant ◽  
Clément Gosselin
Keyword(s):  
Carrying Capacity ◽  
Degree Of Freedom ◽  
Load Carrying Capacity ◽  
Extensive Analysis ◽  
Load Carrying ◽  
Payload Capacity ◽  
Time Optimal ◽  
Two Degree Of Freedom ◽  
Trajectory Optimisation

The load-carrying capacity of manipulators is often considered to be the same throughout their workspace. However, the actual capacity of manipulators largely depends on their posture, their velocity, their acceleration and the limits of their actuators. In this paper, a method is proposed to increase the payload capacity of manipulators through trajectory optimisation. This optimisation is performed on a task basis and therefore, the load-carrying capacity varies from task to task. An extensive analysis of the method is conducted based on its application on a planar RR serial two degree-of-freedom manipulator. This analysis evaluates the ability of the method to find feasible trajectories and compares the results with those obtained using Bang-bang type methods. It is shown that, although the trajectories produced by the proposed method are not time optimal, the method is much more versatile and much simpler to implement than its Bang-bang counterparts.

scholarly journals Performance of BFRP Retrofitted RCC Piles Subjected to Axial Loads

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Anandakumar Ramaswamy ◽  
Selvamony Chachithanantham ◽  
Seeni Arumugam
Keyword(s):  
Axial Compression ◽  
Carrying Capacity ◽  
Compressive Load ◽  
Load Carrying Capacity ◽  
Axial Loads ◽  
Basalt Fibre ◽  
Load Carrying ◽  
Fibre Reinforced Polymer ◽  
Strain Relationship ◽  
Axial Compression Experiment

This paper deals with the behaviour of basalt fibre reinforced polymer (BFRP) composites retrofitted RCC piles subjected to axial compression loads. Currently the awareness of using FRP increases rapidly in engineering fields and also among public. Retrofitting becomes vital for aged and damaged concrete structures, piles, and so forth, to improve its load carrying capacity and to extend the service life. The load carrying capacity of piles retrofitted with basalt unidirectional fabric was studied experimentally. 15 nos. of RCC end bearing pile elements were cast with same reinforcement for axial compression experiment. Three piles were used as conventional elements, another 3 piles were used as double BFRP wrapped pile elements, and remaining 9 piles were used as retrofitted piles with BFRP double wrapping after preloaded to 30%, 60%, and 90% of ultimate load of conventional element. The effects of retrofitting of RCC pile elements were observed and a mathematical prediction was developed for calculation of retrofitting strength. The stress vs. strain relationship curve, load vs. deformation curve, preloaded elements strength losses are tabulated and plotted. Besides, crack patterns of conventional elements and tearing BFRP wrapped elements were also observed. The BFRP wrapped elements and retrofitted elements withstand more axial compressive load than the conventional elements.

scholarly journals Stability and Load-Carrying Capacity of Thin-Walled FRP Composite Z-Profiles under Eccentric Compression

Materials ◽  
2020 ◽  
Vol 13 (13) ◽  
pp. 2956
Author(s):  
Hubert Debski ◽  
Sylwester Samborski ◽  
Patryk Rozylo ◽  
Pawel Wysmulski
Keyword(s):  
Composite Material ◽  
Carrying Capacity ◽  
Progressive Failure ◽  
Compressive Load ◽  
Experimental Tests ◽  
Numerical Results ◽  
Load Carrying Capacity ◽  
Plastic Composite ◽  
Load Carrying ◽  
Thin Walled

This study investigates the effect of eccentric compressive load on the stability, critical states and load-carrying capacity of thin-walled composite Z-profiles. Short thin-walled columns made of carbon fiber-reinforced plastic composite material fabricated by the autoclave technique are examined. In experimental tests, the thin-walled structures were compressed until a loss of their load-carrying capacity was obtained. The test parameters were measured to describe the structure’s behavior, including the phenomenon of composite material failure. The post-critical load-displacement equilibrium paths and the acoustic emission signal enabling analysis of the composite material condition during the loading process were measured. The scope of the study also included performing numerical simulations by finite element method to solve the problem of non-linear stability and to describe the phenomenon of composite material damage based on the progressive failure model. The obtained numerical results showed a good agreement with the experimental characteristics of real structures. The numerical results are compared with the experimental findings to validate the developed numerical model.

scholarly journals Balanced and unbalanced welds for angle compression members

1994 ◽  
Vol 21 (3) ◽  
pp. 396-403 ◽  
Author(s):  
Murray C. Temple ◽  
Sherief S. S. Sakla
Keyword(s):  
Key Words ◽  
Carrying Capacity ◽  
Compressive Load ◽  
Tensile Load ◽  
Effective Length ◽  
Load Carrying Capacity ◽  
Compression Members ◽  
Load Carrying ◽  
Compressive Loads ◽  
Compressive Resistance

Angles used as web members in trusses are often welded to the chords with unbalanced welds. This is necessary because of space limitations. It is not known what effect such a weld has on the compressive load carrying capacity of an angle. The standards and specification examined allow an unbalanced weld for an angle. The justification for using such a weld is based on research conducted on angles in tension. For these members, it was concluded that an unbalanced weld does not affect the tensile load carrying capacity of the angle. Research results for angles with different weld patterns subjected to compressive loads are not available in the literature. Eighteen tests were conducted on angle compression members with various weld patterns. It was determined that an unbalanced weld is detrimental to the load carrying capacity of an intermediate length angle but is beneficial for a slender angle. Key words: angles, column (structural), compressive resistance, effective length, standards, welds.

scholarly journals The effect of water content on the stiffness of seating foams

1986 ◽  
Vol 10 (3) ◽  
pp. 149-152 ◽  
Author(s):  
A. M. Brown ◽  
M. J. Pearcy
Keyword(s):  
National Health Service ◽  
Health Service ◽  
Water Content ◽  
Carrying Capacity ◽  
Deleterious Effect ◽  
Compressive Load ◽  
Pressure Sores ◽  
Load Carrying Capacity ◽  
Effect Of Water ◽  
Load Carrying

The chairbound, disabled person requires a supportive cushion to distribute pressure in order to reduce the risk of pressure sores and any alteration to the load carrying capacity of the cushion may have a deleterious effect on its ability to provide adequate support. The National Health Service supplies two basic grades of polyurethane foam for wheelchair cushions and this study investigated the effect of water content on their compressive load carrying capacity. Both foams became less stiff and exhibited greater than 20% increase in deformation when containing 20% water by volume at loads encountered in seating. This decrease in stiffness may result in a dramatic change in the pressure distribution under a patient particularly if only a small section of the cushion becomes wet. This result emphasizes the need to fit waterproof coverings to these foam cushions and to maintain the integrity of the covering.

scholarly journals Structural Behavior of RC Column Confined by FRP Sheet under Uniaxial and Biaxial Load

Polymers ◽  
2021 ◽  
Vol 14 (1) ◽  
pp. 75
Author(s):  
Huynh-Xuan Tin ◽  
Ngo-Thanh Thuy ◽  
Soo-Yeon Seo
Keyword(s):  
Carrying Capacity ◽  
Biaxial Loading ◽  
Compressive Load ◽  
Load Carrying Capacity ◽  
Reinforced Concrete Column ◽  
Eccentric Load ◽  
Rc Columns ◽  
Rc Column ◽  
Load Carrying ◽  
Frp Sheet

Various researches have been performed to find an effective confining method using FRP sheet in order to improve the structural capacity of reinforced concrete column. However, most of these researches were undertaken for the columns subjected to concentric compressive load or fully confined RC columns. To date, it remains hard to find studies on partially FRP-confined RC columns under eccentric load. In this manner, an experimental investigation was carried out to assess the performance of rectangular RC column with different patterns of CFRP-wrap subject to eccentric loads in this paper. The experiment consists of fourteen mid-scale rectangular RC columns of 200 mm × 200 mm × 800 mm, including five controlled columns and nine CFRP-strengthened ones. All CFRP-strengthened columns were reinforced with one layer of vertical CFRP sheet with the main fiber along the axial axis at four sides, then divided into three groups according to confinement purpose, namely unconfined, partially CFRP-confined, and fully CFRP-confined group. Two loading conditions, namely uniaxially and biaxially eccentric loads, are considered as one of the test parameters. From the test of uniaxial eccentric load, partial and full CFRP-wraps provided 19% and 33% increased load-carrying capacity at an eccentricity-to-column thickness ratio (e/h) of 0.125, respectively, compared to controlled columns, and 8% and 11% at e/h = 0.25, respectively. For the partially CFRP-confined columns subjected to biaxial eccentric load with e/h = 0.125 and 0.25, the load-carrying capacities were improved by 19% and 31%, respectively. This means that the partial confinement with CFRP effectively improves the load-carrying capacity at larger biaxial eccentric load. It was found that the load-carrying capacity could be properly predicted by using code equations of ACI 440.2R-17 and Fib Bulletin 14 Guideline for the full CFRP-confined or partially CFRP-confined columns under uniaxial load. For partially CFRP-confined columns under biaxial loading, however, the safety factors using the Fib calculation process were 20% to 31% lower than that of uniaxially loaded columns.

scholarly journals Experimental study on square hollow stainless steel tube trusses with three joint types and different brace widths under vertical loads

2021 ◽  
Vol 60 (1) ◽  
pp. 519-540
Author(s):  
Wenyuan Kong ◽  
Yongfa Huang ◽  
Zhan Guo ◽  
Xiaoyong Zhang ◽  
Yu Chen
Keyword(s):  
Stainless Steel ◽  
Carrying Capacity ◽  
Failure Modes ◽  
Flexural Rigidity ◽  
Unit Weight ◽  
Stainless Steel Tube ◽  
Load Carrying Capacity ◽  
Surface Plasticity ◽  
Load Carrying ◽  
Better Than

Abstract This article reports the experimental behavior of square hollow stainless steel tubular trusses under static loading. A total of five specimens, including three trusses with K-joint, one truss with N-joint, and one truss with T-joint, were tested to study the effect of different outer widths of brace members and the types of joint on the flexural performance of square hollow stainless steel tubular trusses. The failure modes, flexural rigidity, load carrying capacity, ductility, load versus displacement curves, and load versus strain curves of all the tested specimens are presented. It can be seen that the chords of all specimens experienced surface plasticity. The test results indicate that the specimen with T-joint has the best ductility. The flexural rigidity of the truss with the K-joint is better than that of specimens with N-joint or T-joint. The flexural rigidity of trusses with the K-joint was found to increase with the increase of outer width (D) of the brace members varying from 38 to 80 mm. Besides, the load-carrying capacity per unit weight of the specimen with T-joint is better than that of specimens with N-joint or K-joint.

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