scholarly journals A Transitional Connection Method for the Design of Functionally Graded Cellular Materials

2020 ◽  
Vol 10 (21) ◽  
pp. 7449
Author(s):  
Shihao Liang ◽  
Liang Gao ◽  
Yongfeng Zheng ◽  
Hao Li
Keyword(s):  
Level Set ◽  
Cellular Structure ◽  
Hot Spot ◽  
Transitional Cell ◽  
Optimization Method ◽  
Functionally Graded ◽  
Homogenization Theory ◽  
Connection Method ◽  
Mechanical Performances ◽  
C1 Continuity

In recent years, the functionally graded materials (FGM) with cellular structure have become a hot spot in the field of materials research. For the continuously varying cellular structure in the layer-wise FGM, the connection of gradient cellular structures has become the main problem. Unfortunately, the effect of gradient connection method on the overall structural performance lacks attention, and the boundary mismatch has enormous implications. Using the homogenization theory and the level set method, this article presents an efficient topology optimization method to solve the connection issue. Firstly, a simple but efficient hybrid level set scheme is developed to generate a new level set surface that has the partial features of two candidate level sets. Then, when the new level set surface is formed by considering the level set functions of two gradient base cells, a special transitional cell can be constructed by finding the zero level set of this generated level set surface. Since the transitional cell has the geometric features of two gradient base cells, the shape of the transitional cell fits perfectly with its connected gradient cells on both sides. Thus, the design of FGM can have a smooth connectivity with C1 continuity without any complex numerical treatments during the optimization. A number of examples on both 2D and 3D are provided to demonstrate the characteristics of the proposed method. Finite element simulation has also been employed to calculate the mechanical properties of the designs. The simulation results show that the FGM devised by the proposed method exhibits better mechanical performances than conventional FGM with only C0 continuity.

A structural optimization method based on the level set method using a new geometry-based re-initialization scheme

2010 ◽  
Vol 83 (12) ◽  
pp. 1580-1624 ◽  
Author(s):  
Shintaro Yamasaki ◽  
Shinji Nishiwaki ◽  
Takayuki Yamada ◽  
Kazuhiro Izui ◽  
Masataka Yoshimura
Keyword(s):  
Structural Optimization ◽  
Level Set Method ◽  
Level Set ◽  
Optimization Method ◽  
Initialization Scheme

scholarly journals Extended finite -element method for modeling the mechanical behavior of functionally graded material plates with multiple random inclusions

2017 ◽  
Vol 20 (K3) ◽  
pp. 119-125
Author(s):  
Bang Kim Tran ◽  
Huy The Tran ◽  
Tinh Quoc Bui ◽  
Thien Tich Truong
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Level Set Method ◽  
Level Set ◽  
Functionally Graded Material ◽  
Extended Finite Element Method ◽  
Functionally Graded ◽  
Extended Finite Element ◽  
Graded Material ◽  
Element Method

Functionally graded material is of great importance in many engineering problems. Here the effect of multiple random inclusions in functionally graded material (FGM) is investigated in this paper. Since the geometry of entire model becomes complicated when many inclusions with different sizes appearing in the body, a methodology to model those inclusions without meshing the internal boundaries is proposed. The numerical method couples the level set method to the extended finite-element method (X-FEM). In the X-FEM, the finite-element approximation is enriched by additional functions through the notion of partition of unity. The level set method is used for representing the location of random inclusions. Numerical examples are presented to demonstrate the accuracy and potential of this technique. The obtained results are compared with available refered results and COMSOL, the finite element method software.

scholarly journals Driving force profile design in comb drive electrostatic actuators using a level set-based shape optimization method

2014 ◽  
Vol 51 (2) ◽  
pp. 369-383 ◽  
Author(s):  
Takayo Kotani ◽  
Takayuki Yamada ◽  
Shintaro Yamasaki ◽  
Makoto Ohkado ◽  
Kazuhiro Izui ◽  
...  
Keyword(s):  
Shape Optimization ◽  
Level Set ◽  
Driving Force ◽  
Optimization Method ◽  
Comb Drive ◽  
Electrostatic Actuators ◽  
Force Profile ◽  
Profile Design

Optimal Viscous Damper Placement Using Level Set Topology Optimization Method

2010 ◽  
Author(s):  
Masoud Ansari ◽  
Amir Khajepour ◽  
Ebrahim Esmailzadeh
Keyword(s):  
Topology Optimization ◽  
Level Set ◽  
Discrete Optimization ◽  
Optimization Problem ◽  
Minimum Energy ◽  
Optimization Method ◽  
Discrete Optimization Problem ◽  
Placement Problem ◽  
New Approach ◽  
Optimal Damping

Vibration control has always been of great interest for many researchers in different fields, especially mechanical and civil engineering. One of the key elements in control of vibration is damper. One way of optimally suppressing unwanted vibrations is to find the best locations of the dampers in the structure, such that the highest dampening effect is achieved. This paper proposes a new approach that turns the conventional discrete optimization problem of optimal damper placement to a continuous topology optimization. In fact, instead of considering a few dampers and run the discrete optimization problem to find their best locations, the whole structure is considered to be connected to infinite numbers of dampers and level set topology optimization will be performed to determine the optimal damping set, while certain number of dampers are used, and the minimum energy for the system is achieved. This method has a few major advantages over the conventional methods, and can handle damper placement problem for complicated structures (systems) more accurately. The results, obtained in this research are very promising and show the capability of this method in finding the best damper location is structures.

scholarly journals Segmentation of Meristem Cells by an Automated Optimization Algorithm

2020 ◽  
Vol 10 (23) ◽  
pp. 8523
Author(s):  
Oswaldo Rojas ◽  
Manuel G. Forero ◽  
José M. Menéndez ◽  
Angharad Jones ◽  
Walter Dewitte ◽  
...  
Keyword(s):  
Level Set ◽  
Automatic Segmentation ◽  
Optimization Method ◽  
Intensity Level ◽  
Low Contrast ◽  
Segmentation Methods ◽  
Segmented Images ◽  
Optimization Function ◽  
Confocal Images ◽  
Automated Optimization

Meristem cells are irregularly shaped and appear in confocal images as dark areas surrounded by bright ones. Images are characterized by regions of very low contrast and absolute loss of edges deeper into the meristem. Edges are blurred, discontinuous, sometimes indistinguishable, and the intensity level inside the cells is similar to the background of the image. Recently, a technique called Parametric Segmentation Tuning was introduced for the optimization of segmentation parameters in diatom images. This paper presents a PST-tuned automatic segmentation method of meristem cells in microscopy images based on mathematical morphology. The optimal parameters of the algorithm are found by means of an iterative process that compares the segmented images obtained by successive variations of the parameters. Then, an optimization function is used to determine which pair of successive images allows for the best segmentation. The technique was validated by comparing its results with those obtained by a level set algorithm and a balloon segmentation technique. The outcomes show that our methodology offers better results than two free available state-of-the-art alternatives, being superior in all cases studied, losing 9.09% of the cells in the worst situation, against 75.81 and 25.45 obtained in the level set and the balloon segmentation techniques, respectively. The optimization method can be employed to tune the parameters of other meristem segmentation methods.

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