The Experts below are selected from a list of 1089 Experts worldwide ranked by ideXlab platform
Nicolae Lobontiu - One of the best experts on this subject based on the ideXlab platform.
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substructure compliance matrix model of planar branched Flexure Hinge mechanisms design testing and characterization of a gripper
Mechanism and Machine Theory, 2015Co-Authors: Simona Noveanu, Nicolae Lobontiu, Joshua Lazaro, Dan MandruAbstract:Abstract This paper proposes an analytical compliance-based matrix method to model the quasi-static, small-displacement response of planar branched Flexure-Hinge over-constrained mechanisms. It studies structurally- and kinematically-branched flexible mechanisms comprising several chains that are connected in complex series-parallel configurations and that are acted upon by multiple external/reaction loads. These architectures are substructured or decomposed into simpler chains whose compliances are evaluated from known individual segment compliances. The substructured-chain compliances are subsequently combined with external loads to solve for unknown displacements and reactions and to further evaluate parameters relevant to the mechanism behavior. The method is applied to the design and analysis of a novel displacement-amplified gripper with right circularly corner-filleted Flexure Hinges. The mechanism's mechanical amplification, stiffness, and grip force are evaluated when either full or partial compliance (Flexure-based only) is assumed. The analytical model predictions are confirmed by finite element analysis and by experimental testing of a proof-of-concept prototype. Subsequent analytical-model simulation highlights the relationships between the main geometric parameters and the gripper's performance qualifiers.
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compliance based matrix method for modeling the quasi static response of planar serial Flexure Hinge mechanisms
Precision Engineering-journal of The International Societies for Precision Engineering and Nanotechnology, 2014Co-Authors: Nicolae LobontiuAbstract:Abstract A matrix method is proposed to model the direct and inverse quasi-static response of constrained/over-constrained planar serial mechanisms with Flexure Hinges under bending, axial, and shear planar (three-dimensional) loading and small-deformations. The method uses a basic three-point compliance matrix corresponding to one rigid link and one adjacent Flexure Hinge that are subjected to one point load. This matrix connects the displacements at a point on the rigid link with the load that is applied at another point on it, and the deformations of the Flexure Hinge at its distal point. The quasi-static model of planar serial Flexure-based mechanisms with multiple links under single/multiple point loading results from linearly superimposing all relevant Hinge-link-load triads defined by their three-point matrices. A displacement-amplification planar device with right circularly corner-fileted Flexure Hinges is studied using several refinement stages of the matrix method to generate a model whose predictions are confirmed by finite element simulation.
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Out-of-Plane (Diaphragm) Compliances of Circular-Axis Notch Flexible Hinges with Midpoint Radial Symmetry
Mechanics Based Design of Structures and Machines, 2014Co-Authors: Nicolae LobontiuAbstract:A small-displacement analytical model is proposed for the out-of-plane compliances of notch Flexure Hinges with circular longitudinal axis and midpoint radial symmetry that function as monolithic joints in flexible mechanisms. The Hinges are constructed from several serially connected segments with small and constant out-of-plane width, variable in-plane thickness, and are subjected to coupled bending and torsion. The six compliances of a symmetric notch Hinge are obtained as linear combinations of compliances defining the segments that form one half of the full flexible Hinge. The general analytical model is applied to the circular-axis, right circularly corner-filleted Hinge design whose compliances are validated by finite element simulation. A comparison is performed between the out-of-plane and the in-plane compliances of this Flexure Hinge. The right circularly corner-filleted configuration is also compared to the circular-axis, constant-thickness Flexure Hinge with respect to the out-of-plane static...
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CIRCULAR-AXIS Flexure HingeS
2014Co-Authors: Nicolae Lobontiu, Matt Cullin, Jeffrey Hoffman, Muhammad AliAbstract:Abstract—The paper introduces the analytical planar compliance model of circular-axis symmetric notch Flexure Hinges that can be used as flexible connectors in compliant mechanisms. The circular-axis Flexure design adds an extra parameter, the median circle radius, to the regular straight-axis Flexure design domain. Six general compliances are derived with respect to an end reference frame in terms of only three compliances of half the Flexure Hinge. Two new circular-axis configurations are studied, namely: the right circular Flexure and the right circularly corner-filleted Flexure Hinge. The analytical compliance model predictions of the two designs are confirmed by finite element simulation and experimental tests. Keywords—Flexure, Hinge, compliance, circular Hinge, shape variation is most often utilized, particularly in a predefined design envelope. Usually the Flexures’ shapes are defined by curves that enable the analytical formulation of compliances – the main qualifiers of the quasi-static response of Flexures. The overwhelming majority of Flexure designs have straight longitudinal axis and Fig. 1 illustrates two of the most common configurations: the right circular Flexure Hinge – Fig. 1(a) – and the right circularly corner-filleted Flexure Hinge of Fig. 1(b). More recently, circular-axis Flexure Hinges have been introduced – [13], [14] – such as the ones illustrated in Fig. 2, which are the counterparts of the designs shown i
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Planar Compliances of Symmetric Notch Flexure Hinges: The Right Circularly Corner-Filleted Parabolic Design
IEEE Transactions on Automation Science and Engineering, 2014Co-Authors: Nicolae Lobontiu, Matt Cullin, Todd Petersen, Javier A. Alcazar, Simona NoveanuAbstract:This study proposes a general analytical compliance model for symmetric notch Flexure Hinges composed of segments with constant width and analytically defined variable thicknesses. Applying serial combination and longitudinal/transverse mirroring of base segments, the in-plane compliances of the full Flexure are obtained as functions of one quarter-Flexure compliances. The new right circularly corner-filleted parabolic Flexure Hinge is introduced as an illustration of the general analytical modeling algorithm. Experimental testing and finite element simulation confirm the analytical model predictions for an aluminum Flexure prototype. The planar compliances sensitivity to the relevant geometric parameters is also studied.
Marc In Het Panhuis - One of the best experts on this subject based on the ideXlab platform.
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3D Printed Flexure Hinges for Soft Monolithic Prosthetic Fingers
Soft Robotics, 2016Co-Authors: Rahim Mutlu, Gursel Alici, Marc In Het PanhuisAbstract:Abstract Mechanical compliance is one of the primary properties of structures in nature playing a key role in their efficiency. This study investigates a number of commonly used Flexure Hinges to determine a Flexure Hinge morphology, which generates large displacements under a lowest possible force input. The aim of this is to design a soft and monolithic robotic finger. Fused deposition modeling, a low-cost 3D printing technique, was used to fabricate the Flexure Hinges and the soft monolithic robotic fingers. Experimental and finite element analyses suggest that a nonsymmetric elliptical Flexure Hinge is the most suitable type for use in the soft monolithic robotic finger. Having estimated the effective elastic modulus, flexion of the soft monolithic robotic fingers was simulated and this showed a good correlation with the actual experimental results. The soft monolithic robotic fingers can be employed to handle objects with unknown shapes and are also potential low-cost candidates for establishing soft...
Hongwei Zhao - One of the best experts on this subject based on the ideXlab platform.
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a piezoelectric driven linear actuator by means of coupling motion
IEEE Transactions on Industrial Electronics, 2018Co-Authors: Jianping Li, Hu Huang, Hongwei ZhaoAbstract:A piezoelectric-driven actuator based on coupling motion has been proposed and tested to achieve a large linear working stroke with high resolution. “Z-shaped” Flexure Hinges are exploited for the symmetric Flexure Hinge mechanism to reduce the structural stress. Coupling motion is obtained by placing this symmetric Flexure Hinge mechanism with an angle of $\theta =20^\circ $ to the slider. Experimental results indicate that linear motion with a large working stroke is effectively obtained by this coupling motion; the maximum motion speed is $V_{s}=$ 6057 μm/s and the maximum output force is $F_{g}=$ 350 g. Additionally, the influences of input frequency $f$ and input voltage $U_{e}$ are investigated, and the system kinetic model is established to better analyze the performance of this designed piezoelectric-driven linear actuator.
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a novel trapezoid type stick slip piezoelectric linear actuator using right circular Flexure Hinge mechanism
IEEE Transactions on Industrial Electronics, 2017Co-Authors: Tinghai Cheng, Meng He, Hengyu Li, Xiaohui Lu, Hongwei ZhaoAbstract:A trapezoid-type stick–slip piezoelectric linear actuator using a right circular Flexure Hinge mechanism was proposed, designed, fabricated, and tested with the aim of accomplishing linear driving based on stick–slip motion. The angle adjustment of the trapezoid beam was used for generating lateral motion on the driving foot of the Flexure Hinge mechanism. A method of tuning the lateral motion of the Flexure Hinge mechanism was discussed. Based on the finite-element method, a proper angle of the trapezoid beam was obtained. The analysis results proved that asymmetrical Flexure Hinge mechanism can increase static friction force in slow extension stage and decrease kinetic friction force in quick contraction stage by lateral motion of the driving foot. A prototype was fabricated and its experimental system was established. The mechanical output experiments showed that the prototype achieved maximum output velocity and load of 5.96 mm/s and 3 N at a voltage of 100 V $p-p$ and a frequency of 500 Hz, respectively.
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Design and Experimental Research of a Novel Stick-Slip Type Piezoelectric Actuator
MDPI AG, 2017Co-Authors: Mingxing Zhou, Hongwei Zhao, Zunqiang Fan, Yue Guo, Kun Hong, Hang LiuAbstract:A linear piezoelectric actuator based on the stick-slip principle is presented and tested in this paper. With the help of changeable vertical preload force Flexure Hinge, the designed linear actuator can achieve both large travel stick-slip motion and high-resolution stepping displacement. The developed actuator mainly consists of a bridge-type Flexure Hinge mechanism, a compound parallelogram Flexure Hinge mechanism, and two piezoelectric stacks. The mechanical structure and motion principle of the linear actuator were illustrated, and the finite element method (FEM) is adopted. An optimal parametric study of the Flexure Hinge is performed by a finite element analysis-based response surface methodology. In order to investigate the actuator’s working performance, a prototype was manufactured and a series of experiments were carried out. The results indicate that the maximum motion speed is about 3.27 mm/s and the minimum stepping displacement is 0.29 μm. Finally, a vibration test was carried out to obtain the first natural frequency of the actuator, and an in situ observation was conducted to investigate actuator’s stick-slip working condition. The experimental results confirm the feasibility of the proposed actuator, and the motion speed and displacement are both improved compared with the traditional stick-slip motion actuator
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A novel nanoscratch device compatible with commercial microscope for in situ tests of materials’ mechanics
SAGE Publishing, 2016Co-Authors: Hongwei Zhao, Peng Zhang, Yue Shi, Yanchao Liu, Mingjun Jin, Hui Wang, Shan DongAbstract:For exploring the mechanical properties and behaviors of new materials, a novel in situ nanoscratch device compatible with commercial microscope has been developed. The developed device with specific dimensions of 178 mm × 165 mm × 78 mm includes the coarse positioning module, the precise feed module, the measurement module, and the control module. Integrating the servo motor, worm and gears, ball screw, Flexure Hinge, and piezoelectric actuator, the device can realize macroscopical coarse positioning motion and precise feed motion. A novel arrangement of load sensor and indenter with no middle chain is used to reduce the measurement error. Closed-loop control system is established to guarantee the accuracy of load and displacement control. Mechanical properties of the developed device have been proved by calibrating the load sensor, finite element analysis of Flexure Hinge, and verifying the output performance. The in situ nanoscratch test has been conducted on the single crystal copper. The captured images and finite element analysis prove the feasibility and accuracy of the developed device
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design and experimental performances of a piezoelectric linear actuator by means of lateral motion
Smart Materials and Structures, 2015Co-Authors: Jianping Li, Xiaoqin Zhou, Hongwei Zhao, Mingkun Shao, Xiuquan XuAbstract:A piezoelectric-driven actuator based on the lateral motion principle is proposed in this paper, it can achieve large-stroke linear motion with high resolution. One parallelogram-type Flexure Hinge mechanism and one piezoelectric stack are used to generate the lateral motion. The mechanical structure and working principle are discussed. A prototype was fabricated and a series of experiments were carried out to investigate its working performance. The results indicate that the maximum moving speed is about 14.25 mm s−1, and the maximum output force is 3.43 N, the minimum stepping displacement is about 0.04 μm. The experiments confirm that the lateral motion can be used to design piezoelectric actuators with a large moving stroke and high accuracy with a compact size. This actuator can be used in fast tool servo systems for ultra-precision machining, precision motors for aerospace, focusing systems for optics, and so on.
Rahim Mutlu - One of the best experts on this subject based on the ideXlab platform.
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3D Printed Flexure Hinges for Soft Monolithic Prosthetic Fingers
Soft Robotics, 2016Co-Authors: Rahim Mutlu, Gursel Alici, Marc In Het PanhuisAbstract:Abstract Mechanical compliance is one of the primary properties of structures in nature playing a key role in their efficiency. This study investigates a number of commonly used Flexure Hinges to determine a Flexure Hinge morphology, which generates large displacements under a lowest possible force input. The aim of this is to design a soft and monolithic robotic finger. Fused deposition modeling, a low-cost 3D printing technique, was used to fabricate the Flexure Hinges and the soft monolithic robotic fingers. Experimental and finite element analyses suggest that a nonsymmetric elliptical Flexure Hinge is the most suitable type for use in the soft monolithic robotic finger. Having estimated the effective elastic modulus, flexion of the soft monolithic robotic fingers was simulated and this showed a good correlation with the actual experimental results. The soft monolithic robotic fingers can be employed to handle objects with unknown shapes and are also potential low-cost candidates for establishing soft...
Ephrahim Garcia - One of the best experts on this subject based on the ideXlab platform.
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Two-axis Flexure Hinges with axially-collocated and symmetric notches
Computers & Structures, 2003Co-Authors: Nicolae Lobontiu, Ephrahim GarciaAbstract:The paper introduces a new class of two-axis Flexure Hinges with axially-collocated and symmetric notches as an alternative to the existing Flexure designs with serially-disposed notches. A generic formulation is developed in terms of the geometric curves defining the two notches which includes assessing the capacity of rotation, precision of rotation, sensitivity to parasitic effects, stress values, motion efficiency and shearing effects by means of compliance factors. Closed-form compliance equations are derived for a two-axis Flexure Hinge that is defined by two non-identical parabolic profiles. The analytical model predictions are confirmed by finite element data. A numerical comparison is made of the parabolic Flexure with a constant rectangular cross-section Flexure Hinge in terms of several performance criteria.
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design of symmetric conic section Flexure Hinges based on closed form compliance equations
Mechanism and Machine Theory, 2002Co-Authors: Nicolae Lobontiu, Jeffrey S N Paine, Ephrahim Garcia, Michael GoldfarbAbstract:The paper develops closed-form compliance equations for conic-section (circular, elliptic, parabolic and hyperbolic) Flexure Hinges. Finite element simulation results confirm the theoretical formulation data. The main objectives are to predict the deformation/displacement field of a Flexure Hinge under loading and to assess the precision of rotation for a specific conic Flexure Hinge. A non-dimensional analysis is carried out to discuss both problems. Conclusions are formulated regarding the performance of circular, elliptic, parabolic, and hyperbolic Flexure Hinges.
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Corner-Filleted Flexure Hinges
Journal of Mechanical Design, 2000Co-Authors: Nicolae Lobontiu, Jeffrey S N Paine, Ephrahim Garcia, Michael GoldfarbAbstract:The paper presents an analytical approach to corner-filleted Flexure Hinges. Closed-form solutions are derived for the in-plane compliance factors. It is demonstrated that the corner-filleted Flexure Hinge spans a domain delimited by the simple beam and the right circular Flexure Hinge. A comparison that is made with the right circular Flexure Hinges indicates that the corner-filleted Flexures are more bending-compliant and induce lower stresses but are less precise in rotation. The finite element simulation and experimental results confirmed the model predictions.