Modeling of Multifunctional Porous Tissue Scaffolds With Continuous Deposition Path Plan

2012 ◽  
Author(s):  
A. K. M. B. Khoda ◽  
Ibrahim T. Ozbolat ◽  
Bahattin Koc
Keyword(s):  
Pore Size ◽  
Tool Path ◽  
Medial Axis ◽  
Tissue Scaffolds ◽  
Fabrication Process ◽  
Free Form ◽  
Tissue Scaffold ◽  
Medial Axis Transformation ◽  
Material Deposition ◽  
Continuous Material

A novel modeling technique for porous tissue scaffolds with targeting the functionally gradient variational porosity with continuous material deposition planning has been proposed. To vary the porosity of the designed scaffold functionally, medial axis transformation is used. The medial axis of each layers of the scaffold is calculated and used as an internal feature. The medial axis is then used connected to the outer contour using an optimum matching. The desired pore size and hence the porosity have been achieved by discretizing the sub-regions along its peripheral direction based on the pore size while meeting the tissue scaffold design constraints. This would ensure the truly porous nature of the structure in every direction as well as controllable porosity with interconnected pores. Thus the desired controlled variational porosity along the scaffold architecture has been achieved with the combination of two geometrically oriented consecutive layers. A continuous, interconnected and optimized tool-path has been generated for successive layers for additive-manufacturing or solid free form fabrication process. The proposed methodology has been computationally implemented with illustrative examples. Furthermore, the designed example scaffolds with the desired pore size and porosity has been fabricated with an extrusion based bio-fabrication process.

Modeling and Fabrication of Hollowed Scaffolds With Interconnected Variational Porosity Architecture

2011 ◽  
Author(s):  
Bashir Khoda ◽  
Ibrahim T. Ozbolat ◽  
Bahattin Koc
Keyword(s):  
Pore Size ◽  
Tool Path ◽  
Free Form ◽  
Design Constraint ◽  
Tissue Scaffold ◽  
Porosity Level ◽  
Successive Layer ◽  
Micro Nozzle ◽  
Design Error ◽  
Internal Architecture

This paper presents a novel computer-aided modeling of 3D hollowed tissue scaffolds with a controlled internal architecture. Functionally gradient variational porosity architecture is proposed with continuous material deposition planning scheme. The complex internal architecture of scaffolds is discritized into sub-regions accumulated from ruling lines that are generated from outer to inner features. The desired pore size and hence the porosity have been achieved by geometrically partitioning those sub-regions based on the area while meeting the tissue scaffold design constraint. Thus the desired controlled variational porosity along the scaffold architecture has been achieved with the combination of two geometrically oriented consecutive layers. A continuous, interconnected and optimized tool-path has been generated for both layers aiming at the standard solid free form fabrication process. A zigzag pattern tool-path has been proposed for accumulated sub-region layer. And a concentric spiral like optimal tool-path pattern has been derived for the successive layer to ensure fabricatable continuity along the structure. A micro-nozzle biomaterial deposition system driven by NC motion control has been used to fabricate sample designed structure with desired pore size and porosity level. Besides proper characterization of the fabrication sample has been performed to validate the proposed methodology. Moreover a comparative study between proposed design and conventional cartesian coordinate scaffolds has been performed. The results demonstrate significant reduction in design error with the proposed method.

Modeling of Flow Rate, Pore Size, and Porosity for the Dispensing-Based Tissue Scaffolds Fabrication

2009 ◽  
Vol 131 (3) ◽  
Author(s):  
M. G. Li ◽  
X. Y. Tian ◽  
X. B. Chen
Keyword(s):  
Mechanical Properties ◽  
Pore Size ◽  
Compressive Stress ◽  
Flow Rate ◽  
Tissue Scaffolds ◽  
Fabrication Process ◽  
Scaffold Material ◽  
Pore Sizes ◽  
Moving Speed

Dispensing technique is one of the promising solid freeform (SFF) methods to fabricate scaffolds with controllable pore sizes and porosities. In this paper, a model to represent the dispensing-based SFF fabrication process is developed. Specifically, the mechanical properties of the scaffold material and its influence on the fabrication process are examined; the flow rate of the scaffold material dispensed and the pore size and porosity of the scaffold fabricated in the process are represented. In order to generate scaffold strands without either tensile or compressive stress, the optimal moving speed of the dispensing head is determined from the flow rate of the scaffold material dispensed. Experiments were also carried out to illustrate the effectiveness of the model developed.

Medial Axis Transform of Planar Shapes With Free-Form Curve Boundary

2010 ◽  
Author(s):  
Qiang Fu ◽  
Zezhong C. Chen
Keyword(s):  
Tool Path ◽  
Medial Axis ◽  
Free Form ◽  
Medial Axis Transform ◽  
Pocket Milling ◽  
Planar Shapes ◽  
Tree Data ◽  
Tracing Algorithm ◽  
Boundary Tracing ◽  
Tree Data Structure

Medial axis transform (MAT) is a very useful shape interrogation tool in NC tool path generation for pocket milling. This paper presents a new, efficient approach to calculating MATs of planar profiles with boundaries of free-form curves. The proposed approach is mainly based on profile boundary tracing and decomposition. By studying the basic elements of MAT and their geometric properties, several algorithms of finding contact circles are developed. The boundary tracing algorithm can handle profiles with/without internal holes. For a profile without internal holes, it is continuously divided into simpler sub-profiles while travelling along the boundary, and a tree data structure is adopted to keep track of the boundary decomposition process. For a profile with internal holes, it is divided into several simple profiles without internal holes. After generating the MAT of each simple profile, the completed MAT can be found by combining these MATs. This proposed approach is implemented and some illustrative samples are presented to demonstrate its advantages.

Tool Path Generation for Five-Axis Controlled Machining of Free-Form Surface Using Barrel Tool: Control of Contact Point on Cutting Edge

2020 ◽  
Author(s):  
Tomonobu Suzuki ◽  
Koichi Morishige
Keyword(s):  
Tool Path ◽  
Contact Point ◽  
Cutting Edge ◽  
Free Form ◽  
End Mill ◽  
Ball End Mill ◽  
Surface Machining ◽  
Free Form Surface ◽  
The Cost ◽  
Five Axis

Abstract This study aimed to improve the efficiency of free-form surface machining by using a five-axis controlled machine tool and a barrel tool. The barrel tool has cutting edges, with curvature smaller than the radius, increasing the pick feed width compared with a conventional ball end mill of the same tool radius. As a result, the machining efficiency can be improved; however, the cost of the barrel tool is high and difficult to reground. In this study, a method to obtain the cutting points that make the cusp height below the target value is proposed. Moreover, a method to improve the tool life by continuously and uniformly changing the contact point on the cutting edge is proposed. The usefulness of the developed method is confirmed through machining simulations.

Application of Convex Hull for Tool Interference Avoidance in 5-Axis CNC Machining

1996 ◽  
Author(s):  
Yuan-Shin Lee ◽  
Tien-Chien Chang
Keyword(s):  
Convex Hull ◽  
Tool Path ◽  
Correction Method ◽  
Nc Machining ◽  
Cnc Machining ◽  
Free Form ◽  
Interference Avoidance ◽  
Tool Interference ◽  
Free Form Surface ◽  
Free Form Surfaces

Abstract In this paper, a methodology of applying convex hull property in solving the tool interference problem is presented for 5-axis NC machining of free-form surfaces. Instead of exhausted point-by-point checking for possible tool interference, a quick checking can be done by using the convex hull constructed from the control polygon of free-form surface modeling. Global tool interference in 5-axis NC machining is detected using the convex hull of the free-form surface. A correction method for removing tool interference has also been developed to generate correct tool path for 5-axis NC machining. The inter-surface tool interference can be avoided by using the developed technique.

scholarly journals A High-Efficiency Impeller Channel Quasi-Triangular Tool Path Planning Method Based on Template Trajectory Mapping

2018 ◽  
Vol 36 (6) ◽  
pp. 1216-1223
Author(s):  
Feiyan Han ◽  
Juan Wei ◽  
Bin Feng ◽  
Wu Zhang
Keyword(s):  
Path Planning ◽  
Tool Path ◽  
Planning Method ◽  
Free Form ◽  
Physical Domain ◽  
Tool Path Planning ◽  
Surface Machining ◽  
Mapping Model ◽  
Trajectory Mapping ◽  
Free Form Surface

The manufacturing technology of an integral impeller is an important indicator for measuring the manufacturing capability of a country. Its manufacturing process involves complex free-form surface machining, a time consuming and error-prone process, and the tool path planning is considered as a critical issue of free-form surface machining but still lacks a systematic solution. In this paper, aiming at the tool path planning of the impeller channel, a quasi-triangular tool path planning method based on parametric domain template trajectory mapping is proposed. The main idea is to map the template trajectory to physical domain by using the mapping model of parametric domain to the physical domain to obtain the actual machining path. Firstly, the trajectory mapping model of parametric domain to physical domain is established using the morphing technique, and the template trajectory mapping method in the parametric domain is given. Secondly, the clean-up boundary of the impeller channel is determined in the parametric domain, and the quasi-triangular template trajectory of the impeller channel is defined. Finally, taking a certain type of impeller as an example, the quasi-triangular tool path of the impeller channel is calculated, and the tool path calculation time of this method is compared with that of the traditional isometric offset method. The result shows that the computational efficiency is improved by 45% with this method, which provides a new method for the rapid acquisition of NC machining tool path for impeller channels. In addition, the simulation and actual machining are carried out, the results show that the shape of actual cutting traces on the surface of the impeller channel is quasi-triangular, showing that this method is effective and feasible.

scholarly journals Iso-level tool path planning for free-form surfaces

2014 ◽  
Vol 53 ◽  
pp. 117-125 ◽  
Author(s):  
Qiang Zou ◽  
Juyong Zhang ◽  
Bailin Deng ◽  
Jibin Zhao
Keyword(s):  
Path Planning ◽  
Tool Path ◽  
Free Form ◽  
Tool Path Planning ◽  
Free Form Surfaces

Development of Embedded Linux CNC System Based on ARM9

2011 ◽  
Vol 467-469 ◽  
pp. 906-911 ◽  
Author(s):  
Shu Kun Cao ◽  
Chang Lei Wang ◽  
Hui Zhang ◽  
Jie Lv ◽  
Chang Zhong Wu
Keyword(s):  
Tool Path ◽  
Free Form ◽  
Cnc System ◽  
Open Cnc ◽  
Standard Interface ◽  
Stepper Motors ◽  
Tool Posture ◽  
Cross Platform ◽  
Five Axis ◽  
The Way

Five-axis machining area of free surface is proposed by based on ARM9 and Linux open CNC system's overall structure of the CNC system hardware and software architecture. The system adopts the mode of the host computer PC, the lower computer ARM9 development board. PC completes the model of space surface and generates tool path by Simultaneous Multi-objective Optimization Algorithm on Free-form Surface Five-Axis Machining Tool Path and Tool Posture. The lower computer applies MYSQL database to storage and manage cutter location point information. Other modules access the database through ODBC standard interface. ARM9and PC utilize the way of cross-platform socket data transmission, the stepper motors is controlled by the way of constant acceleration - deceleration.

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