Optical Waveguide Theory

생체의 모델링과 Simulation

A paradigm shift has emerged over the last decade pointing to an exciting research area dealing with the harnessing of elastic structural instabilities for ‘smart’ purposes in a variety of venues. Among the different types of unstable responses, buckling is a phenomenon that has been known for centuries, and yet it is generally avoided through special design modifications. Increasing interest in the design of smart devices and mechanical systems has identified buckling and postbuckling response as a favorable behavior. The objective of this topical review is to showcase the recent advances in buckling-induced smart applications and to explain why buckling responses have certain advantages and are especially suitable for these particular applications. Interesting prototypes in terms of structural forms and material uses associated with these applications are summarized. Finally, this review identifies potential research avenues and emerging trends for using buckling and other elastic instabilities for future innovations.

https://iopscience.iop.org/article/10.1088/0964-1726/24/6/063001/pdf

Buckling-induced smart applications: recent advances and trends

Nonlinear finite element analysis of solids and structures by M.A. Crisfield

A review of topology optimization for additive manufacturing: Status and challenges

This paper develops a robust edge-based template matching algorithm for displacement measurement of compliant mechanisms under a scanning electron microscope (SEM). The algorithm consists of three steps. First, the Sobel gradient operator and a self-adaptive segment strategy are used to establish the shape model in which the gradient directions of the object's edge points are calculated. Second, a similarity criterion based on image gradients that is robust to illumination change and image noise is utilized for template matching to obtain the coarse results. The third step is to refine the matching results by using an orientation-guided subpixel interpolation strategy. A series of simulations is conducted, and the results show that the proposed algorithm enjoys great robustness against strong image noise and gray-value fluctuation, as well as small rotations and background interferences, and thus is suitable for processing SEM images of compliant mechanisms. Finally, the application of the proposed algorithm in the measurement of the spring constant of the flexure hinges with a straight beam form under a SEM is demonstrated.

A robust edge-based template matching algorithm for displacement measurement of compliant mechanisms under scanning electron microscope

The orthogonal displacement amplification mechanism is used to output and amplify the displacement perpendicular to the direction of the input force, and its configuration often uses a typical bridge-type. However, the bridge-type amplifier to achieve orthogonal shift conversion must enter the bidirectional symmetric input forces, otherwise the output will produce parasitic displacement. In view of this problem, the topology optimization method is used to find the new configuration of the displacement amplification mechanism, so that it can still realize the orthogonal displacement transformation under the unidirectional input force condition. Based on the solid isotropic material with penalization (SIMP) topological description method, the ratio of output and input displacements is maximized as the objective function, the ratio of parasitic displacement and output displacement as one of constraint functions, and the topological optimization mathematical model of the compliant orthogonal displacement amplifier is established under the unidirectional input force. The sensitivity information of the objective and constraint functions is deduced by the adjoint matrix method, and the optimization problem is solved by the method of moving asymptotes (MMA). The topology optimization results of orthogonal displacement amplifier are given through numerical examples, and the effect of spring stiffness on the topology optimization result is also discussed. Finally, the parasitic motions of the displacement amplification mechanism obtained from topology optimization and the bridge-type amplification mechanism are compared through the finite element analysis and experiment. Finite element simulation and experiment confirm the correctness and validity of the proposed method.

Topological design of compliant orthogonal displacement amplification mechanism under the unidirectional input force

Flexure hinges have been widely used in precision positioning, precision measurement and other fields due to its high-precision features. Traditional notch flexure hinges often exhibit local stress, which limits the range of motion and reduces the fatigue life of flexure-based mechanisms. This paper proposes a conceptual method for designing flexure hinges with distributed stress by using the topology optimization approach. The topology optimization model is developed. The objective function is presented by equally minimizing the ratio of axial displacement and bending displacement and the maximum stress. A global P-norm stress measure is used to reduce the stress level of flexure hinges. The solid isotropic material with penalization (SIMP) is adopted to describing the topology optimization problem. Numerical examples are used to demonstrate the validity of the proposed method.

Topology Optimization of Flexure Hinges with Distributed Stress for Flexure-Based Mechanisms


 This paper presents a novel wheel-legged mobile robot with a reconfigurable frame, which uses a compliant kaleidocycles inspired spring-hinged eight-bar mechanism. The kinematic model of the mechanism is established and the relationships between actual rotation angle and the joint angles is thoroughly obtained in the spherical coordinate system. According to the analysis of the multivariable potential energy surface, the relationship among multistable performance, under-actuated behavior and potential mechanism energy is studied. On account of under-actuated kinematic relationship and multistability of the proposed mechanism, a cable-driven approach is used and its feasibility is finally verified by the experiment of the prototype robot.

A Novel Reconfigurable Wheel-Legged Mobile Mechanism

This study is proposed to solve the compliant mechanism de facto hinge (point flexure) issue by developing a new problem formulation. The main idea is to introduce an additional objective function which is to minimize the distance between the outputs of two types finite element analysis (FEA). A ratio formed formulation is developed based on the method and examined within the continuum type topology optimization framework. Numerical examples are provided to confirm the validity of the proposed method. It is shown that the proposed method gives compliant mechanisms that completely free of one-node connected hinges.

Benliang Zhu

Papers

A robust edge-based template matching algorithm for displacement measurement of compliant mechanisms under scanning electron microscope

Topological design of compliant orthogonal displacement amplification mechanism under the unidirectional input force

Topology Optimization of Flexure Hinges with Distributed Stress for Flexure-Based Mechanisms

A Novel Reconfigurable Wheel-Legged Mobile Mechanism

Topology optimization of hinge-free compliant mechanisms using a two-step FEA method