Path Planning for Functionally Graded Materials in Hollow Tissue Scaffold Printing

2011 ◽  
Author(s):  
Ibrahim T. Ozbolat
Keyword(s):  
Path Planning ◽  
Functionally Graded Materials ◽  
Functionally Graded ◽  
Layer By Layer ◽  
Graded Materials ◽  
Tissue Scaffold ◽  
Material Deposition ◽  
Zigzag Pattern ◽  
Graded Material ◽  
Planning Methodology

This study proposes a new path planning methodology to control functionally graded materials in hollowed scaffold printing for tissue engineering. Based on ruled surface construction from our earlier work [1], ruling lines are postprocessed for continuous path planning with uniform material deposition. Besides, arc fitting is used to reduce over-deposition by enabling non-stop deposition at the sharp turns. Layer-by-layer deposition is progressed through consecutive layers of ruling line based zigzag pattern followed by a biarc fitted spiral pattern. Functionally graded material properties are then mapped based on parametric distances from hollow features.

Design of a New Parametric Path Plan for Additive Manufacturing of Hollow Porous Structures With Functionally Graded Materials

2014 ◽  
Vol 14 (4) ◽  
Author(s):  
Ibrahim T. Ozbolat ◽  
A. K. M. B. Khoda
Keyword(s):  
Additive Manufacturing ◽  
Path Planning ◽  
Functionally Graded Materials ◽  
Three Dimensional ◽  
Functionally Graded ◽  
Relaxation Techniques ◽  
Layer By Layer ◽  
Porous Structures ◽  
Graded Materials ◽  
Voronoi Regions

In this paper, a novel path planning approach is proposed to generate porous structures with internal features. The interconnected and continuous deposition path is designed to control the internal material composition in a functionally graded manner. The proposed layer-based algorithmic solutions generate a bilayer pattern of zigzag and spiral toolpath consecutively to construct heterogeneous three-dimensional (3D) objects. The proposed strategy relies on constructing Voronoi diagrams for all bounding curves in each layer to decompose the geometric domain and discretizing the associated Voronoi regions with ruling lines between the boundaries of the associated Voronoi regions. To avoid interference among ruling lines, reorientation and relaxation techniques are introduced to establish matching for continuous zigzag path planning. In addition, arc fitting is used to reduce over-deposition, allowing nonstop deposition at sharp turns. Layer-by-layer deposition progresses through consecutive layers of a ruling-line-based zigzag pattern followed by a spiral path deposition. A biarc fitting technique is employed through isovalues of ruling lines to generate G1 continuity along the spiral deposition path plan. Functionally graded material properties are then mapped based on a parametric distance-based weighting technique. The proposed approach enables elimination or minimization of over-deposition of materials, nonuniformity on printed strands and discontinuities on the toolpath, which are shortcomings of traditional zigzag-based toolpath plan in additive manufacturing (AM). In addition, it provides a practical path for printing functionally graded materials.

The Elastic-Viscoelastic Correspondence Principle for Functionally Graded Materials, Revisited

2003 ◽  
Vol 70 (3) ◽  
pp. 359-363 ◽  
Author(s):  
S. Mukherjee ◽  
Glaucio H. Paulino
Keyword(s):  
Functionally Graded Materials ◽  
Functionally Graded Material ◽  
Correspondence Principle ◽  
Functionally Graded ◽  
Graded Materials ◽  
One Dimensional ◽  
Space And Time ◽  
Graded Material ◽  
Nonhomogeneous Materials ◽  
Exponentially Graded

Paulino and Jin [Paulino, G. H., and Jin, Z.-H., 2001, “Correspondence Principle in Viscoelastic Functionally Graded Materials,” ASME J. Appl. Mech., 68, pp. 129–132], have recently shown that the viscoelastic correspondence principle remains valid for a linearly isotropic viscoelastic functionally graded material with separable relaxation (or creep) functions in space and time. This paper revisits this issue by addressing some subtle points regarding this result and examines the reasons behind the success or failure of the correspondence principle for viscoelastic functionally graded materials. For the inseparable class of nonhomogeneous materials, the correspondence principle fails because of an inconsistency between the replacements of the moduli and of their derivatives. A simple but informative one-dimensional example, involving an exponentially graded material, is used to further clarify these reasons.

Incremental Melting and Solidification Process/Mechanical Characterization of Functionally Graded Al-Si Alloys

2008 ◽  
Vol 587-588 ◽  
pp. 400-404
Author(s):  
P. Pinto ◽  
L. Mazare ◽  
Delfim Soares ◽  
F.S. Silva
Keyword(s):  
Mechanical Properties ◽  
Functionally Graded Materials ◽  
Phase Distribution ◽  
Solidification Process ◽  
Functionally Graded ◽  
Graded Materials ◽  
Graded Material ◽  
Gradual Variation ◽  
Melting And Solidification

The Incremental Melting and Solidification Process (IMSP) is a relatively new field for material processing for the production of functionally graded materials. In this process a controlled liquid bath is maintained at the top of the component where new materials are added changing the components composition. Thus, a functionally graded material is obtained with a varying composition along one direction of the component. This paper deals with the influence of one of the process parameters, namely displacement rates between heating coil and mould, in order to evaluate its influence on both metallurgical and mechanical properties of different Al-Si alloys. Hardness and phase distribution, along the main castings axis, were measured. To better assess and characterize the process, two different Al-Si alloys with and without variation of chemical composition along the specimen were analysed. Results demonstrate that a gradual variation of metallurgical and mechanical properties along the component is obtained. It is also shown that Al-Si functionally graded materials can be produced by the incremental melting and solidification process. Results show that the displacement rate is very important on metallurgical and mechanical properties of the obtained alloy.

Задачи о дисперсии волн в неоднородных волноводах: методы решения (обзор). Часть I

2021 ◽  
Vol 27 (2) ◽  
pp. 227-260
Author(s):  
С. И. Жаворонок ◽  
Keyword(s):  
Functionally Graded Materials ◽  
Functionally Graded Material ◽  
Matrix Method ◽  
Degrees Of Freedom ◽  
Normal Wave ◽  
Wave Dispersion ◽  
Functionally Graded ◽  
Graded Materials ◽  
Generalized Fourier Series ◽  
Graded Material

A brief review of the modern state-of-the art and tendencies of further development of various methods of solution of wave dispersion problems in heterogeneous functionally graded elastic waveguides is presented. Main types of functionally graded materials and structures, including gradient thon-walled structures, and their main engineering applications is discussed. The main difficulties of modelling of the stress-strain state of functionally graded shells and plates are pointed, as well as the possible ways to overcome such difficulties. The main theoretical bases of definition of effective constitutive constants of functionally graded materials and their possible estimates used in the practice are considered. Main dependencies of the effective constitutive constants of a functionally graded material on coordinates used for the mathematical modelling of the dynamics are also shown. The statement of the dynamics problem for a functionally graded waveguide and the appropriate statement of the normal wave dispersion problem are pointed. The presented Part I of the review consider some analytical methods of solution of dispersion problems, mainly the matrix ones based on the formulation of the steady dynamics problem in the image space as a first-order ordinary differential equations system. The state vectors corresponding to the useful Cauchy and Stroh formalisms are introduced, and the appropriate governing equations and the boundary conditions on waveguide’s faces are presented. Classical methods for solving the steady dynamics problem for a laminated waveguide are briefly described, which could be a basis for the further approximation of a functionally graded material by a system of layers with constant properties, i.e. the transfer matrix method, its main modifications developed to ensure the stability of calculations, and the global matrix method. Then, the intensively developed last 15 years reverberation matrix method, stiffness matrix method, and the Peano series method are discussed. Some key solutions of the wave dispersion problems for heterogeneous layers are presented; such solutions improve the efficiency of approximation of a functionally graded structure by a laminated one. The implicit solution of the general problem of steady dynamics for a waveguide with arbitrary gradation law is shown. The key features of the discussed matrix methods are pointed briefly as well as their main drawbacks. In the Part II, the main attention will be paid to methods of semi-analytical solution of dispersion problems based on the approximation of a waveguide by an equivalent system with a finite number of degrees of freedom: power series, generalized Fourier series, semi-analytical finite elements. spectral elements, as well as methods based on various theories of plates and shells.

scholarly journals MULTILAYER COATINGS Ti/TiN, Cr/CrN AND W/WN DEPOSITED BY MAGNETRON SPUTTERING FOR IMPROVEMENT OF ADHESION TO BASE MATERIALS

2015 ◽  
Vol 55 (6) ◽  
pp. 388 ◽  
Author(s):  
Jakub Horník ◽  
Stanislav Krum ◽  
David Tondl ◽  
Maxim Puchnin ◽  
Pavel Sachr ◽  
...  
Keyword(s):  
Functionally Graded Materials ◽  
Scratch Test ◽  
Functionally Graded ◽  
Point Of View ◽  
Multilayer Coatings ◽  
Graded Materials ◽  
Protective Function ◽  
Base Materials ◽  
Graded Layers ◽  
Graded Material

The paper deals with evaluation of single and multilayer layer PVD coatings based on Cr and Ti widely used in tool application. Additionally, W and WN based coating which are not so widespread were designed and deposited as functionally graded material. The coatings properties were evaluated from the point of view of hardness and adhesion. The hardness measuring was carried out using nanoindentation method. The scratch test was performed to test adhesion. Moreover, the presence of metallic interlayer in functionally graded materials further increases the coating adhesion by gradually approaching its composition to the substrate. Coatings consisting of W and WN have showed very good adhesion. With regard to the results of the scratch test, the multilayer coatings of CrN, TiN and WN have increased adhesion and can be assumed to have their protective function improved. Results will be appliedin development of functionally graded layers for functionally graded materials.

On Accurate Numerical Evaluation of Stress Intensity Factors and T-Stress in Functionally Graded Materials

2005 ◽  
Vol 492-493 ◽  
pp. 403-408 ◽  
Author(s):  
Jeong Ho Kim ◽  
Glaucio H. Paulino
Keyword(s):  
Stress Intensity ◽  
Functionally Graded Materials ◽  
Stress Intensity Factors ◽  
Integral Form ◽  
Functionally Graded ◽  
Intensity Factors ◽  
Graded Materials ◽  
Center Crack ◽  
T Stress ◽  
Graded Material

This paper revisits the interaction integral method to evaluate both the mixed-mode stress intensity factors and the T-stress in functionally graded materials under mechanical loading. A nonequilibrium formulation is developed in an equivalent domain integral form, which is naturally suitable to the finite element method. Graded material properties are integrated into the element stiffness matrix using the generalized isoparametric formulation. The type of material gradation considered includes continuum functions, such as an exponential function, but the present formulation can be readily extended to micromechanical models. This paper presents a fracture problem with an inclined center crack in a plate and assesses the accuracy of the present method compared with available semi-analytical solutions.

Fabrication of ZrO2-SUS Functionally Graded Materials by Slip Casting

2008 ◽  
Vol 368-372 ◽  
pp. 1823-1824 ◽  
Author(s):  
Xin He ◽  
Hai Yan Du ◽  
Wei Wang ◽  
Wei Jing ◽  
Chang Liu
Keyword(s):  
Mechanical Properties ◽  
Chemical Composition ◽  
Functionally Graded Materials ◽  
Functionally Graded Material ◽  
Slip Casting ◽  
Functionally Graded ◽  
Metal Interface ◽  
Graded Materials ◽  
Metal Joint ◽  
Graded Material

TZP/SUS304 functionally graded material (FGM) was developed by slip casting. Microscopic observations demonstrated that the chemical composition and microstructure of TZP/SUS FGM distributed gradually in stepwise way, eliminating the macroscopic ceramic/metal interface occurred in traditional ceramic/metal joint. Each interface of layers connected well without evident defects, and the mechanical properties of TZP/SUS system strongly depended on constitutional variation.

Biomimetic Functionally Graded Materials: Synthesis by Impeller-Dry-Blending

2009 ◽  
Vol 3 ◽  
pp. 37-49 ◽  
Author(s):  
D.T. Chavara ◽  
Cyndi X. Wang ◽  
Andrew Ruys
Keyword(s):  
Functionally Graded Materials ◽  
Low Cost ◽  
Functionally Graded ◽  
Orthopaedic Implant ◽  
Materials Synthesis ◽  
Mollusc Shell ◽  
Graded Materials ◽  
Commercial Viability ◽  
Graded Material ◽  
Concentration Changes

Functionally graded materials (FGMs) can be found naturally in many biological structures, for example bamboo and the mollusc shell. They are defined as having a compositional or microstructural gradient, for example the gradation in fibre content in bamboo stems. A continuous bulk functionally graded material has the potential to be an ideal orthopaedic implant for load bearing applications. Due to the fabrication complexities involved in the production of these continuous bulk functionally graded materials, commercialisation and fabrication are still proving to be a challenge to researchers worldwide. This paper presents an overview of the redesigned novel commercially viable process known as the Impeller-Dry-Blending (IDB) process. Results presented in this paper of fabricated functionally graded materials illustrate the potential of IDB to produce continuous bulk functionally graded materials consisting of either compositional or porosity concentration changes. The successful fabrication of these continuous bulk functionally graded materials at such a low cost clearly demonstrates the commercial viability of the IDB process.

scholarly journals Frequency Analysis for Functionally Graded Material Cylindrical Shells: A Significant Case Study

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Rabia Anwar ◽  
Madiha Ghamkhar ◽  
Muhammad Imran Khan ◽  
Rabia Safdar ◽  
Muhammad Zafar Iqbal ◽  
...  
Keyword(s):  
Functionally Graded Materials ◽  
Natural Frequencies ◽  
Constitutive Relations ◽  
Cylindrical Shells ◽  
Frequency Equation ◽  
Functionally Graded ◽  
Graded Materials ◽  
Simply Supported ◽  
Love’S Shell Theory ◽  
Graded Material

Cylindrical shells play an important role for the construction of functionally graded materials (FGMs). Functionally graded materials are valuable in order to develop durable materials. They are made of two or more materials such as nickel, stainless steel, zirconia, and alumina. They are extremely beneficial for the manufacturing of structural elements. Functionally graded materials are broadly used in several fields such as chemistry, biomedicine, optics, and electronics. In the present research, vibrations of natural frequencies are investigated for different layered cylindrical shells, those constructed from FGMs. The behavior of shell vibration is based on different parameters of geometrical material. The problem of the shell is expressed from the constitutive relations of strain and stress with displacement, as well as it is adopted from Love’s shell theory. Vibrations of natural frequencies (NFs) are calculated for simply supported-simply supported (SS-SS) and clamped-free (C-F) edge conditions. The Rayleigh–Ritz technique is employed to obtain the shell frequency equation. The shell equation is solved by MATLAB software.

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