Optimization of a Bend-Twist-and-Sweep Compliant Mechanism

Calogero, Joseph; Frecker, Mary; Wissa, Aimy; Hubbard, James E.

doi:10.1115/smasis2014-7518

Cited by 3 publications

(13 citation statements)

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“…Furthermore, the stiffness is assumed to be constant for all angles. Contact-aided compliant mechanisms such as the bendtwist-and-sweep compliant mechanism have complex, three-dimensional geometries and nonlinear stiffness due to self-contact, where the CCM has a different stiffness before and after self-contact [7]. The stiffness of such CCMs is more appropriately calculated using finite element modeling or experimental data.…”

Section: Model Comparison Methodology and Experimental Setupmentioning

confidence: 99%

“…The optimization problem is stated in Eqs. (4)- (7). The objective function is to minimize the root-mean-square error (RMSE) between the model and experimental kinematics (Eq.…”

Section: Model Tuning Algorithmmentioning

confidence: 99%

“…These mechanisms can vary from a simple single-point contact to multipoint curved contact surfaces in separate parts of the mechanism [3][4][5][6]. Beyond gripping, CCMs can have nonlinear stiffness and stress relief capabilities, and be designed for path generation [3,[7][8][9][10][11][12][13][14][15]. Several examples of ongoing efforts to model compliant mechanism deformation and kinematics using the finite element method can be found in the literature [16][17][18].…”

Section: Introductionmentioning

confidence: 99%

“…More complex wing morphing, specifically simultaneous deformation in all three spatial directions, is required to achieve the biologically inspired continuous vortex gait [10,30]. A CCM called the bendtwist-and-sweep compliant mechanism has been designed and optimized for maximized deflections during upstroke with minimized stress and mass [7]. This compliant mechanism is tailored for simultaneous bending, twist, and sweep.…”

Section: Introductionmentioning

confidence: 99%

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Tuning of a Rigid-Body Dynamics Model of a Flapping Wing Structure With Compliant Joints

Calogero

Frecker

Hasnain

et al. 2017

Journal of Mechanisms and Robotics

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A method for validating rigid-body models of compliant mechanisms under dynamic loading conditions using motion tracking cameras and genetic algorithms is presented. The compliant mechanisms are modeled using rigid-body mechanics as compliant joints (CJ): spherical joints with distributed mass and three-axis torsional spring dampers. This allows compliant mechanisms to be modeled using computationally efficient rigid-body dynamics methods, thereby allowing a model to determine the desired stiffness and location characteristics of compliant mechanisms spatially distributed into a structure. An experiment was performed to validate a previously developed numerical dynamics model with the goal of tuning unknown model parameters to match the flapping kinematics of the leading edge spar of an ornithopter with contact-aided compliant mechanisms (CCMs), compliant mechanisms that feature self-contact to produce nonlinear stiffness, inserted. A system of computer motion tracking cameras was used to record the kinematics of reflective tape and markers placed along the leading edge spar with and without CCMs inserted. A genetic algorithm was used to minimize the error between the model and experimental marker kinematics. The model was able to match the kinematics of all markers along the spars with a root-mean-square error (RMSE) of less than 2% of the half wingspan over the flapping cycle. Additionally, the model was able to capture the deflection amplitude and harmonics of the CCMs with a RMSE of less than 2 deg over the flapping cycle.

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Section: Model Comparison Methodology and Experimental Setupmentioning

confidence: 99%

“…The optimization problem is stated in Eqs. (4)- (7). The objective function is to minimize the root-mean-square error (RMSE) between the model and experimental kinematics (Eq.…”

Section: Model Tuning Algorithmmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Tuning of a Rigid-Body Dynamics Model of a Flapping Wing Structure With Compliant Joints

Calogero

Frecker

Hasnain

et al. 2017

Journal of Mechanisms and Robotics

Self Cite

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“…In order to achieve a bio-inspired wing gait called continuous vortex gait, the wings of the UAV need to bend and sweep simultaneously. So, this can be achieved by inserting the bend and sweep compliant mechanism into the leading edge wing of the UAV [14].…”

Section: Issn: 2643-8224mentioning

confidence: 99%

Preliminary Design and Computational Fluid Dynamic analysis of Flapping Wing of Micro Aerial Vehicle for Low Reynolds Numbers Regime

Altememe¹,

Hall²,

Altememe³

2019

Int J Aeronaut Aerosp Eng

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This research describes the investigation of the behavior of the flow over a 2D Flapping airfoil for flapping wing of Micro Aerial Vehicles (FWMAV) at very low Reynolds number regieme. The behavior of the flow wake at the trailing edge is studied by the analysis of streamlines for each incidence angle and results are compared by the study of two different flapping airfoils at two different fluids. The use of Fluid Structure Interaction (FSI) simulation has shown accuracy in predicting lift and drag forces at different angles of attack for upstroke and down stroke. This work simulates a classical flow pattern (Von Karman Street) that can form as fluid flows past a flapping NACA0012 airfoil, and S1223 airfoil at low Reynolds numbers and low velocities. These two airfoils have been selected and investigated by using basic computational fluid dynamics and fluid structure interaction modules. The S1223 airfoil, designed by University of Illinois at Urbana and the NACA0012 airfoil were selected for their high lift characteristics at low Reynolds number regime. Simulations were also conducted to check the lift and drag forces for both airfoils at low Reynolds number regime. Velocity distributions were analyzed at different angles of attack for these airfoils. The magnitude and the frequencies of the oscillation generated by the fluid around the airfoils were computed and compared between the airfoils.

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A dynamic spar numerical model for passive shape change

Calogero

Frecker

Hasnain

et al. 2016

Smart Mater. Struct.

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A three-dimensional constraint-driven dynamic rigid-link numerical model of a flapping wing structure with compliant joints (CJs) called the dynamic spar numerical model is introduced and implemented. CJs are modeled as spherical joints with distributed mass and spring-dampers with coupled nonlinear spring and damping coefficients, which models compliant mechanisms spatially distributed in the structure while greatly reducing computation time compared to a finite element model. The constraints are established, followed by the formulation of a state model used in conjunction with a forward time integrator, an experiment to verify a rigid-link assumption and determine a flapping angle function, and finally several example runs. Modeling the CJs as coupled bi-linear springs shows the wing is able to flex more during upstroke than downstroke. Coupling the spring stiffnesses allows an angular deformation about one axis to induce an angular deformation about another axis, where the magnitude is proportional to the coupling term. Modeling both the leading edge and diagonal spars shows that the diagonal spar changes the kinematics of the leading edge spar verses only considering the leading edge spar, causing much larger axial rotations in the leading edge spar. The kinematics are very sensitive to CJ location, where moving the CJ toward the wing root causes a stronger response, and adding multiple CJs on the leading edge spar with a CJ on the diagonal spar allows the wing to deform with larger magnitude in all directions. This model lays a framework for a tool which can be used to understand flapping wing flight.

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Optimization of a Bend-Twist-and-Sweep Compliant Mechanism

Cited by 3 publications

References 0 publications

Tuning of a Rigid-Body Dynamics Model of a Flapping Wing Structure With Compliant Joints

Tuning of a Rigid-Body Dynamics Model of a Flapping Wing Structure With Compliant Joints

Preliminary Design and Computational Fluid Dynamic analysis of Flapping Wing of Micro Aerial Vehicle for Low Reynolds Numbers Regime

A dynamic spar numerical model for passive shape change

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