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

Author(s):  
Ibrahim T. Ozbolat ◽  
A. K. M. B. Khoda

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.

2014 ◽  
Vol 20 (6) ◽  
pp. 511-522 ◽  
Author(s):  
Pierre Muller ◽  
Jean-Yves Hascoet ◽  
Pascal Mognol

Purpose – The purpose of this paper is to propose an evaluation of toolpaths for additive manufacturing of functionally graded materials (FGM) parts to ensure the manufacturing of parts in compliance with the desired material distribution. The selection of an appropriate path strategy is critical when manufacturing FGM parts. Design/methodology/approach – The selection of a path strategy is based on a process modeling and an additive laser melting (ALM) system control. To do that, some path strategies are selected, simulated and compared. Findings – The comparison of some paths strategies was applied on a study case from the biomedical field. Test-parts were manufactured and analyzed. Results show a good correlation between the simulated and the deposited material distributions. The evaluation of toolpaths based on the process modeling and the system control was validated. Originality/value – Nowadays, FGM parts manufactured with ALM processes are not functional. To move from these samples to functional parts, it is necessary to have a global approach of the manufacturing procedure centered on the path planning. Few methodologies of path planning are adapted to FGM parts but are still limited.


Author(s):  
Priyambada Nayak ◽  
Amir Armani

Although some conventional manufacturing technologies are capable of producing functionally graded materials, only a few additive manufacturing processes are able to build functionally graded materials with complex distribution of material composition. To exploit this unique advantage, we have developed a new methodology capable of optimization of material distribution for three-dimensional parts for any given conditions. Representation of material distribution was done through a new technique by extending the nonuniform rational basis spline surfaces to four-dimensional space. Mori–Tanaka, Levin, and Tamura–Tomota–Ozawa models were employed for the estimation of effective material properties of functionally graded structures. Subroutines were developed in a commercial finite element software to enable the analysis of parts made from functionally graded material. A constrained particle swarm optimization method was selected and implemented to optimize the material composition distribution taking into account the additive manufacturing limitations. As a case study, the material distribution optimization of a functionally graded femur bone plate under thermomechanical loading was considered. The objective was to maximize the safety factor; i.e. the ratio of local yield strength of the functionally graded plate over the von Mises stress. The results showed significant improvement compared to nonoptimal part and demonstrated the efficacy of the proposed methodology.


Author(s):  
Ibrahim T. Ozbolat

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.


Materials ◽  
2017 ◽  
Vol 10 (12) ◽  
pp. 1368 ◽  
Author(s):  
Uwe Scheithauer ◽  
Steven Weingarten ◽  
Robert Johne ◽  
Eric Schwarzer ◽  
Johannes Abel ◽  
...  

Author(s):  
Yuen-Shan Leung ◽  
Huachao Mao ◽  
Yong Chen

Functionally graded materials (FGM) possess superior properties of multiple materials due to the continuous transitions of these materials. Recent progresses in multi-material additive manufacturing (AM) processes enable the creation of arbitrary material composition, which significantly enlarges the manufacturing capability of FGMs. At the same time, the fabrication capability also introduces new challenges for the design of FGMs. A critical issue is to create the continuous material distribution under the fabrication constraints of multi-material AM processes. Using voxels to approximate gradient material distribution could be one plausible way for additive manufacturing. However, current FGM design methods are non-additive-manufacturing-oriented and unpredictable. For instance, some designs require a vast number of materials to achieve continuous transitions; however, the material choices that are available in a multi-material AM machine are rather limited. Other designs control the volume fraction of two materials to achieve gradual transition; however, such transition cannot be functionally guaranteed. To address these issues, we present a design and fabrication framework for FGMs that can efficiently and effectively generate printable and predictable FGM structures. We adopt a data-driven approach to approximate the behavior of FGM using two base materials. A digital material library is constructed with different combinations of the base materials, and their mechanical properties are extracted by Finite Element Analysis (FEA). The mechanical properties are then used for the conversion process between the FGM and the dual material structure such that similar behavior is guaranteed. An error diffusion algorithm is further developed to minimize the approximation error. Simulation results on four test cases show that our approach is robust and accurate, and the framework can successfully design and fabricate such FGM structures.


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