Hongchuan Zhang

Bio: Hongchuan Zhang is an academic researcher from South China University of Technology. The author has contributed to research in topic(s): Topology optimization & Compliant mechanism. The author has an hindex of 6, co-authored 19 publication(s) receiving 171 citation(s).

Design of compliant mechanisms using continuum topology optimization: A review

Abstract: Compliant mechanisms have become an important branch of modern mechanisms. Unlike conventional rigid body mechanisms, compliant mechanisms transform the displacement and force at least partly through the deformation of their structural components, which can offer a great reduction in friction, lubrication and assemblage. Therefore, compliant mechanisms are particularly suitable for applications in microscale/nanoscale manipulation systems. The significant demand of practical applications has also promoted the development of systematic design methods for compliant mechanisms. Several methods have been developed to design compliant mechanisms. In this paper, we focus on the continuum topology optimization methods and present a survey of the state-of-the-art design advances in this research area over the past 20 years. The presented overview can be helpful to those engaged in the topology optimization of compliant mechanisms who desire to be apprised of the field’s recent state and research tendency.

Topology optimization of bistable mechanisms with maximized differences between switching forces in forward and backward direction

Abstract: A small bistable mechanism with a strong robustness to external disturbances is eagerly desired in many practical applications. The difference between the switching forces in forward and backward directions is a critical parameter influencing the robustness. However, the difference decreases with the size of bistable mechanisms. This study designs robust bistable mechanisms with maximized differences between the reaction forces at the desired critical points using topology optimization. The reaction forces are obtained by finite element analysis (FEA). Geometric constraints of the minimum length scale in topology optimization are employed to reduce the requirement on fabrication. An additive hyperelasticity technique is utilized to ensure the convergence of the nonlinear finite element problems. An approximate expression of the sensitivity is deduced to obtain the derivatives from ANSYS. The experimental studies indicate that the optimized mechanism is more stable than the conventional mechanisms based on inclined straight beams or preshaped curved beams.

Origami Kaleidocycle-Inspired Symmetric Multistable Compliant Mechanisms

Abstract: Compliant kaleidocycles can be widely used in a variety of applications, including deployable structures, origami structures, and metamorphic robots, due to their unique features of continuous rotatability and multistability. Inspired by origami kaleidocycles, a type of symmetric multistable compliant mechanism with an arbitrary number of units is presented and analyzed in this paper. First, the basic dimension constraints are developed based on mobility analysis using screw theory. Second, the kinematic relationships of the actual rotation angle are obtained. Third, a method to determine the number of stabilities and the position of stable states, including the solution for the parameterized boundaries of stable regions, is developed. Finally, experimental platforms are established, and the validity of the proposed multistable mechanisms is verified.

Design of Planar Large-Deflection Compliant Mechanisms With Decoupled Multi-Input-Output Using Topology Optimization

Abstract: This paper presents a method for topology optimization of large-deflection compliant mechanisms with multiple inputs and outputs by considering the coupling issue. First, the objectives of the design problem are posed by modeling the output loads using several springs to enable control of the input–output behavior. Second, a scheme is proposed to obtain a completely decoupled mechanism. Both input coupling and output coupling are considered. Third, with the implementation of an energy interpolation scheme to stabilize the numerical simulations, the geometrical nonlinearity is considered to appropriately capture the large displacements of compliant mechanisms. Finally, several numerical examples are presented to demonstrate the validity of the proposed method. Comparison studies with the obtained results without considering the coupling issues are also presented.

A novel flexural lamina emergent spatial joint

Abstract: Origami and lamina emergent compliant hinges offer favorable potential applications for large-stroke compliant mechanisms. However, due to coupling problems and nonlinear deformation of the spatial beams, most lamina emergent compliant hinges should not be flexible in more than one direction. Thus, spatially compliant mechanisms are usually in the form of complex three-dimensional structures, which are difficult to miniaturize. In this paper, we present a flexural Lamina Emergent Spatial (LES) joint that can decompose large spatial rotations by employing the combination of a Out-of-plane Rotational Part(ORP) and a In-plane Rotational Part(IRP). First, the geometric model of the LES joint is established. Second, a closed-form expression for the compliance matrix of the initial configuration is derived for normalized analysis of the compliance ratios. Third, the relationship between the beam aspect ratios and compliance ratios is analyzed to obtain the overall normalized planar structure of the LES joint. Finally, a detailed analysis is performed to compare the optimized results with that of the finite element analysis, and the feasibility of the LES joint is verified by practical application prototypes.

Design of compliant mechanisms using continuum topology optimization: A review

Abstract: Compliant mechanisms have become an important branch of modern mechanisms. Unlike conventional rigid body mechanisms, compliant mechanisms transform the displacement and force at least partly through the deformation of their structural components, which can offer a great reduction in friction, lubrication and assemblage. Therefore, compliant mechanisms are particularly suitable for applications in microscale/nanoscale manipulation systems. The significant demand of practical applications has also promoted the development of systematic design methods for compliant mechanisms. Several methods have been developed to design compliant mechanisms. In this paper, we focus on the continuum topology optimization methods and present a survey of the state-of-the-art design advances in this research area over the past 20 years. The presented overview can be helpful to those engaged in the topology optimization of compliant mechanisms who desire to be apprised of the field’s recent state and research tendency.

Topology optimization of bistable mechanisms with maximized differences between switching forces in forward and backward direction

Abstract: A small bistable mechanism with a strong robustness to external disturbances is eagerly desired in many practical applications. The difference between the switching forces in forward and backward directions is a critical parameter influencing the robustness. However, the difference decreases with the size of bistable mechanisms. This study designs robust bistable mechanisms with maximized differences between the reaction forces at the desired critical points using topology optimization. The reaction forces are obtained by finite element analysis (FEA). Geometric constraints of the minimum length scale in topology optimization are employed to reduce the requirement on fabrication. An additive hyperelasticity technique is utilized to ensure the convergence of the nonlinear finite element problems. An approximate expression of the sensitivity is deduced to obtain the derivatives from ANSYS. The experimental studies indicate that the optimized mechanism is more stable than the conventional mechanisms based on inclined straight beams or preshaped curved beams.

An Origami-Based Medical Support System to Mitigate Flexible Shaft Buckling

Abstract: This paper presents the development of an origami-inspired support system (the OriGuide) that enables the insertion of flexible instruments using medical robots. Varying parameters of a triangulated cylindrical origami pattern were combined to create an effective highly compressible anti-buckling system that maintains a constant inner diameter for supporting an instrument and a constant outer diameter throughout actuation. The proposed origami pattern is composed of two repeated patterns: a bistable pattern to create support points to mitigate flexible shaft buckling and a monostable pattern to enable axial extension and compression of the support system. The origami-based portion of the device is combined with two rigid mounts for interfacing with the medical robot. The origami-based portion of the device is fabricated from a single sheet of polyethylene terephthalate. The length, outer diameter, and inner diameter that emerge from the fold pattern can be customized to accommodate various robot designs and flexible instrument geometries without increasing the part count. The support system also adds protection to the instrument from external contamination.

A multi-response optimal design of bistable compliant mechanism using efficient approach of desirability, fuzzy logic, ANFIS and LAPO algorithm

Abstract: Compliant mechanisms are promising candidates in precision engineering, soft robotics, space, and bioengineering due to their advantages of free friction, free lubricant, no backlash, monolithic structure, and minimal assembly However, designing and analyzing of compliant mechanisms are facing the high complexity due to a coupling of kinematic and mechanical behavior in comparison to rigid-body mechanisms Especially, considering a multi-objective optimization design for compliant mechanisms, the problem is more complicated Thus, this paper presents a new efficient hybrid methodology for solving the multi-objective optimization design A hybridization is developed through a combination of finite element method, statistical technique, desirability function approach, fuzzy logic system, adaptive neuro-fuzzy inference system (ANFIS), and Lightning attachment procedure optimization (LAPO) A bistable compliant mechanism is investigated as an application example of the proposed method First, design variables of the mechanism are determined, and then central composite design is employed to construct a numerically experimental matrix Though using analysis of variance and Taguchi approach, the design variables are refined to make new populations Subsequently, desirability values of two performances of the mechanism are computed, and the results are transferred into the fuzzy logic system The output of fuzzy logic system is considered as single combined objective function By developing the ANFIS model, the relation between the refined design variables and the output of fuzzy logic system is established Finally, LAPO algorithm is adopted for solving the multi-objective optimization problem for the mechanism Three numerical examples are investigated to validate the performance efficiency of the proposed method The results demonstrate that the proposed method is more efficient than Taguchi-based fuzzy logic Besides, through Wilcoxon signed rank test and Friedman test, it reveals that the performances of proposed approach are superior to those of the Jaya algorithm and TLBO algorithm The results of this article can be extended for other complex compliant mechanisms as well as optimization problems with multiple objective functions and more complex constraints

A CPRBM-based method for large-deflection analysis of contact-aided compliant mechanisms considering beam-to-beam contacts

Abstract: Contact-aided compliant mechanisms (CCMs) utilize contact to achieve enhanced functionality. The contact phenomenon of CCMs increases the difficulties of their analysis and design, especially when they exhibit beam-to-beam contact. Considering the particularity of CCMs analysis, which is more about the mechanisms’ deformation, this paper presents a numerical method to analyze the large deflection and stress of the CCMs considering beam-to-beam contacts. Based on our previous work on beam-to-rigid contact, the large deformation of general beams in CCMs is modeled by using the chained pseudo-rigid-body model (CPRBM). An approximation based on the geometric information of CPRBM is proposed in this paper to rapidly determine the moving boundary curve for beam-to-beam contact constraints. The static equilibrium configuration of CCMs is solved by minimizing its potential energy function under the geometric constraints from the boundary curves of contacts. A formulation is also provided to evaluate the normal stress along the deformed beam based on the deformation of CPRBM’s torsional springs. Numerical examples and finite element analysis are used to verify the feasibility and accuracy of the proposed method.