Design and Development of a Two Degree-of-Freedom Rotational Flexure Mechanism for Precise Unbalance Measurements

2017 ◽  
Vol 9 (4) ◽  
Author(s):  
Zhao Hongzhe ◽  
Ren Siyuan ◽  
Li Ming ◽  
Zhang Shuqing
Keyword(s):  
Calibration Procedure ◽  
Degree Of Freedom ◽  
Load Carrying Capacity ◽  
Shape Parameters ◽  
Rotational Stiffness ◽  
Element Analysis ◽  
Flexure Mechanism ◽  
Leaf Springs ◽  
Load Carrying ◽  
Two Degree Of Freedom

To measure unbalanced moments, the knife-edge is used as a support module in traditional platforms, but performances rapidly deteriorate as the edge is worn down. In this paper, considering the requirements of measurements, a two degree-of-freedom (DOF) flexure mechanism is, thus, presented to overcome this drawback. First, off-axis stiffness and manufacturability are improved qualitatively by means of configuration analysis. Then, four generalized cross-spring pivots are exploited in the 2DOF flexure mechanism, and the geometric parameters are analyzed to achieve approximately constant rotational stiffness and reduced center shift simultaneously, which benefits calibration procedure and measurement precision. Models are further developed to determine the shape parameters of leaf-springs and transducer performances. Therefore, a low rotational stiffness is obtained to ensure a high resolution for measurements, and a high load-carrying capacity is achieved via strength checking. Finally, finite element analysis (FEA) is carried out to validate the proposed design, and experimental results demonstrate that the developed platform is capable of unbalance measurements with a high precision and resolution.

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.

Design of a 2-DOF Flexure Platform for Unbalance Measurement

2016 ◽  
Author(s):  
Hongzhe Zhao ◽  
Shuqing Zhang ◽  
Siyuan Ren ◽  
Xiaodong Zhou
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Calibration Procedure ◽  
High Accuracy ◽  
Knife Edge ◽  
Practical Application ◽  
Rotational Stiffness ◽  
Element Analysis ◽  
Flexure Mechanism ◽  
The Finite Element Analysis

The traditional measurement platform for unbalance moment exploits the knife-edge as the support module but its performance rapidly deteriorates as the edge is worn down. In this paper, the flexure mechanism is utilized to overcome this drawback. The generalized cross-spring pivot is designed to achieve the approximate constant rotational stiffness and reduced center shift, which will benefit the control system and calibration procedure. A 2-DOF flexure mechanism is thus proposed by taking the practical application into account, such as manufacturability, performances of sensor and actuator. The finite element analysis (FEA) is carried out to verify the validation of design. Finally, the experiment is implemented and the results show a high accuracy: the error is less than 2.4g·mm even though the payload is up to 7kg and the unbalance moment is 100g·mm.

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.

Investigation of Burst Pressure in T-Joints With Wall-Thinning by Using FEA

2017 ◽  
Author(s):  
Atsushi Yamaguchi
Keyword(s):  
Carrying Capacity ◽  
Safety Margin ◽  
Pressure Vessels ◽  
Burst Pressure ◽  
Load Carrying Capacity ◽  
Working Pressure ◽  
Element Analysis ◽  
T Joints ◽  
Wall Thinning ◽  
Load Carrying

Boilers and pressure vessels are heavily used in numerous industrial plants, and damaged equipment in the plants is often detected by visual inspection or non-destructive inspection techniques. The most common type of damage is wall thinning due to corrosion under insulation (CUI) or flow-accelerated corrosion (FAC), or both. Any damaged equipment must be repaired or replaced as necessary as soon as possible after damage has been detected. Moreover, optimization of the time required to replace damaged equipment by evaluating the load carrying capacity of boilers and pressure vessels with wall thinning is expected by engineers in the chemical industrial field. In the present study, finite element analysis (FEA) is used to evaluate the load carrying capacity in T-joints with wall thinning. Burst pressure is a measure of the load carrying capacity in T-joints with wall thinning. The T-joints subjected to burst testing are carbon steel tubes for pressure service STPG370 (JIS G3454). The burst pressure is investigated by comparing the results of burst testing with the results of FEA. Moreover, the maximum allowable working pressure (MAWP) of T-joints with wall thinning is calculated, and the safety margin for the burst pressure is investigated. The burst pressure in T-joints with wall thinning can be estimated the safety side using FEA regardless of whether the model is a shell model or a solid model. The MAWP is 2.6 MPa and has a safety margin 7.5 for burst pressure. Moreover, the MAWP is assessed the as a safety side, although the evaluation is too conservative for the burst pressure.

DESIGN AND ANALYSIS OF AN INTEGRATED THREE- BAY THERMOPLASTIC COMPOSITE WINGBOX

2021 ◽  
Author(s):  
VINCENZO OLIVERI ◽  
GIOVANNI ZUCCO ◽  
MOHAMMAD ROUHI ◽  
ENZO COSENTINO ◽  
RONAN O’HIGGINS ◽  
...  
Keyword(s):  
Variable Stiffness ◽  
Thermoplastic Composite ◽  
High Fidelity ◽  
Material System ◽  
Load Carrying Capacity ◽  
Element Analysis ◽  
Single Piece ◽  
Load Carrying ◽  
Post Buckling ◽  
Composite Material System

The design of a multi-part aerospace structural component, such as a wingbox, is a challenging process because of the complexity arising from assembly and integration, and their associated limitations and considerations. In this study, a design process of a stiffeners-integrated variable stiffness three-bay wingbox is presented. The wingbox has been designed for a prescribed buckling and post-buckling performance (a prescribed real testing scenario) and made from thermoplastic composite material system (Carbon-PEEK) with the total length of three meters. The stiffeners and spars are integrated into the top and bottom panels of the wingbox resulting a single-piece blended structure with no fasteners or joints. The bottom skin also has an elliptical cut-out for access purposes. The composite tows are steered around this cutout for strain concentration reduction purposes. The fiber/tow steering in the top skin bays (compression side) has also been considered for improved compression-induced buckling load carrying capacity. The proposed design has been virtually verified via high fidelity finite element analysis.

Finite Element Analysis of the Static Performance of a Self-Slot-Compensating Aerostatic Bearing

2011 ◽  
Vol 199-200 ◽  
pp. 749-753
Author(s):  
Xiao Bo Zuo ◽  
Jian Min Wang ◽  
Chao Liang Guan ◽  
Juan Li
Keyword(s):  
Finite Element ◽  
Reynolds Equation ◽  
Geometric Parameters ◽  
Load Carrying Capacity ◽  
The Finite Element Method ◽  
Aerostatic Bearing ◽  
Element Analysis ◽  
Consistent Condition ◽  
Load Carrying ◽  
Static Performance

The static performance of an aerostatic bearing with angled surface self-slot-compensation is analyzed. The consistent condition was applied to unitize the Reynolds equation of different forms and the finite element method (FEM) was used to solve the equation. The load carrying capacity (LCC) and the stiffness of the bearing was obtained and the influence of the geometric parameters was discussed. It is concluded that this self-compensating aerostatic bearing can achieve a good performance; the geometric parameters of the gap are interactive, and should be rationally matched.

Reliability analysis of wood I-joists

1993 ◽  
Vol 20 (4) ◽  
pp. 564-573 ◽  
Author(s):  
R. O. Foschi ◽  
F. Z. Yao
Keyword(s):  
Reliability Analysis ◽  
Carrying Capacity ◽  
Failure Modes ◽  
Limit State ◽  
Load Carrying Capacity ◽  
Limit States ◽  
Element Analysis ◽  
Strength Limit ◽  
Reliability Method ◽  
Load Carrying

This paper presents a reliability analysis of wood I-joists for both strength and serviceability limit states. Results are obtained from a finite element analysis coupled with a first-order reliability method. For the strength limit state of load-carrying capacity, multiple failure modes are considered, each involving the interaction of several random variables. Good agreement is achieved between the test results and the theoretical prediction of variability in load-carrying capacity. Finally, a procedure is given to obtain load-sharing adjustment factors applicable to repetitive member systems such as floors and flat roofs. Key words: reliability, limit state design, wood composites, I-joist, structural analysis.

A Numerical Investigation of Laterally Loaded Steel Fin Pile Foundations

2020 ◽  
Author(s):  
Te Pei ◽  
Tong Qiu ◽  
Jeffrey A. Laman
Keyword(s):  
Carrying Capacity ◽  
Load Transfer ◽  
Lateral Load ◽  
Steel Plates ◽  
Pile Foundations ◽  
Load Carrying Capacity ◽  
Element Analysis ◽  
Fea Model ◽  
Load Carrying ◽  
Maximum Improvement

Abstract The present study comprehensively evaluates the improvement in lateral load-carrying capacity of steel pipe piles by adding steel plates (fins) at grade level. This configuration of steel fin pile foundations (SFPFs) is effective for applications where high lateral loads are encountered and rapid pile installation is advantageous. An integrated finite element analysis (FEA) was conducted. The FEA utilized an Abaqus model, first developed to account for the nonlinear soil-pile interaction, and then calibrated and validated against well-documented experimental and filed tests in the literature. The validated FEA model was subsequently used to conduct a parametric study to understand the effect of fin geometry on the load transfer mechanism and the response of SFPFs subjected to lateral loading at pile head. The behavior of SFPFs at different displacement levels and load levels was studied. The effect of the relative density of soil on the performance of SFPFs was also investigated. Based on the numerical simulation results, the optimal fin width for maximum improvement in lateral load-carrying capacity was suggested and the underlining mechanism affecting the efficiency of fins was explained.

scholarly journals Response of a Two-Degree-of-Freedom Vibration System with Rough Contact Interfaces

2019 ◽  
Vol 2019 ◽  
pp. 1-13
Author(s):  
Zhiqiang Huang ◽  
Xun Peng ◽  
Gang Li ◽  
Lei Hao
Keyword(s):  
Natural Frequency ◽  
Degree Of Freedom ◽  
Element Analysis ◽  
Chaotic Motions ◽  
First Order ◽  
Vibration Properties ◽  
Ground System ◽  
Jump Frequencies ◽  
Two Degree Of Freedom ◽  
Seismic Vibrator

This paper is focused on the influence of the rough contact interfaces on the dynamics of a coupled mechanical system. For this purpose, a two-degree-of-freedom model of a coupled seismic-vibrator-rough-ground system is proposed with which the nonlinear vibration properties are analyzed. In this model, the force-deflection characteristic of the contact interfaces is determined by finite element analysis. By analyzing the undamped free vibration, it was found that the variation of the second-order natural frequency with amplitude increases with rougher contact interfaces; however, the amplitude has little influence on the first-order natural frequency of the system. For the harmonic excited analysis, the jump frequencies and hysteretic region both decrease with rougher contact interfaces. Moreover, it is inferred from the bifurcation diagrams that, increasing the excitation force, the system can bring about chaotic motions on rough contact interfaces.

Numerical Analysis on Loading Capacity of Continuous Composite Slab with Steel Deck

2011 ◽  
Vol 71-78 ◽  
pp. 898-902
Author(s):  
Yuan Qing Wang ◽  
Jong Su Sung ◽  
Yong Jiu Shi
Keyword(s):  
Numerical Analysis ◽  
Carrying Capacity ◽  
Load Carrying Capacity ◽  
Element Analysis ◽  
Composite Slab ◽  
Steel Rebar ◽  
Continuous Slab ◽  
Load Carrying ◽  
Negative Moment ◽  
Reinforced Steel

Composite slab with steel sheeting deck is considered a continuous slab when it is under a constructional situation. Nevertheless, many recent researches are focused on simply supported slab. In order to determine the load carrying capacity regarding various rebar ratio on negative moment region, a numerical analysis was carried out by using finite element analysis. The result of analysis shows that the reinforced steel rebar increases load carrying capacity. Moreover, it has shown that the reinforced length of steel rebar also affect the load carrying capacity.

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