Heterogeneous Object Modeling Research Articles

Universal material template for heterogeneous objects with applications to additive manufacturing

Additive manufacturing processes enable the fabrication of the material with multiscale complexities. However, to efficiently model the material compositions and microstructures on multiple design scales is an issue for most existing heterogeneous object modeling methods. To solve this problem, a universal material template and its associated heterogeneous object model are developed in this paper. The developed material template aims to provide a standardized description of the material’s microstructures. The material descriptors defined in the material template can be used in the developed heterogeneous object model to describe the spatially varied material compositions and microstructures on multiple design scales. In addition to that, a multiscale rendering method is also developed in this paper which can reconstruct the microstructure of multiscale materials defined in the material template. Both mesh and voxel models can be generated by the developed rendering technique for visualization and fabrication purposes. To further validate the effectiveness of the proposed template and rendering methods, the microstructures of three different types of commonly used materials in additive manufacturing processes are reconstructed from the pre-defined material templates. A heterogeneous object model with functional graded multiscale materials is also successfully generated and fabricated by an existing commercial additive manufacturing process. In general, the developed material template and its associated modeling and rendering methods provide the foundation for the multiscale design and modeling of parts fabricated by the additive manufacturing process.

Iso-material contour representation for process planning of heterogeneous object model

Abstract Additive manufacturing is emerging as the preferred process for making heterogeneous objects. Planning the deposition of material is more complex for heterogeneous objects as the material variation has to be tracked along the path. This paper proposes an iso-material contour representation to generate the process plan for additive manufacturing given a smooth representation of heterogeneous object model. These contours represent the iso-material paths for deposition. As these paths shift along the direction of the gradation of material distribution, the deposition respects the gradient of the designed material distribution unlike iso-oriented paths generated by a raster scan method. Since the paths have the same material composition, material frequent change in the material composition is avoided, which, in turn, avoids the uneven deposition caused by the frequent start and stop of deposition while the material is being changed along the paths generated by the traditional raster scan. Associativity between the contours and the corresponding designed material feature is maintained, and therefore, changes in material composition are automatically propagated to the process plan.

Level set-based heterogeneous object modeling and optimization

This paper presents a level set-based heterogeneous object (HO) modeling and optimization method. This HO model employs multiple level set functions to build the geometry, utilizes zero-value level set contours as material source profiles, and realizes functionally graded material blending with a signed distance-based blending function. More importantly, this HO model supports the concurrent structure and material optimization because of the unified level set framework for both structure and material composition representation. Beyond macro HO, heterogeneous meta-material optimization will be addressed as well. This new model remedies the shortage of traditional HO models that focus more on modeling but less on optimization. About the numerical optimization, design update with the sensitivity result will be carefully discussed, since there includes infeasible terms (in domain integration format). Two strategies will be explored to address this issue: ignoring the infeasible part of the sensitivity, or transforming the sensitivity result into a purely boundary integration-based expression. A few numerical examples will be studied to prove the effectiveness of the proposed HO modeling and optimization method.

3D modeling of natural heterogeneous objects: an introduction to methods and algorithms

3D modeling of natural heterogeneous objects: an introduction to methods and algorithms

A modeling and optimization method for heterogeneous objects based on complex networks theory

Heterogeneous objects (HEO) which refer to product models with spatially different material compositions or structures have attracted extensive attention from different disciplines due to emerging techniques in design and manufacturing in the last decade. The recent additive manufacturing technologies have bridges the gap between the design and manufacture for HEO. The models are the core for additive manufacturing, while designing heterogeneous objects is still a complex task. In this paper, a novel HEO modeling method based on complex networks theory is first proposed. It models the hollowing Voronoi cell as nodes and force relationship among them as edges. The nodes are weighted by the stress distribution in the mode. The force-directed algorithm is applied to construct the initial porous model. A mixed genetic algorithm is then used to accurately adjust the count and distribution of porous structures, which is necessary to reduce consumption and printing costs. The volume minimized HEO model is archived finally.

Heterogeneous Composition Adaptation With Material Convolution Control Features

Controlling and accomplishing the desired functional material composition in a heterogeneous object (HO) is a close loop process and requires frequent remodeling-and-analysis. Thus, flexibility and capability to efficiently modify the existing CAD model of a heterogeneous object are essential aspects of heterogeneous object modeling. The current work unfolds such capabilities of the developed material convolution surface approach. The geometric and material control features associated with the approach demonstrate the potential to modify existing material-distributions to remodel complex material variations and assure rapid heterogeneous composition adaptations. Convolution material primitives (CMPs), material potential functions, and heterogeneous and grading enclosure are manipulated to achieve desired material compositions across the heterogeneous region. The manipulation process for each control feature has been established. A few examples of modeling and modifying complex material-distributions have been reported for the validation of work.

A Design and Fabrication Method for a Heterogeneous Model of 3D Bio-Printing

Due to the advantages of control over shape and properties, multimaterial parts have potential for a broad range of biomedical engineering applications. A type of multimaterial part processing method based on digital design and manufacturing has been put forward to solve the problems associated with multimaterial part formation. A modeling platform for a heterogeneous object (HEO) part based on a material distribution control function and hierarchical contour loop was designed and utilized to characterize the material distribution in the HEO model. The hierarchical algorithm of the point color and surface texture based on the topological structure was studied and provided the basic data for the material construction area. An HEO part was fabricated using a custom-made 3-D printing system. The results showed that the digital processing method could effectively solve the problem of HEO part material definition and could realize the integrated design and manufacture of the geometry, material and function of biological parts.

Adaptive direct slicing of volumetric attribute data represented by trivariate B-spline functions

We introduce a framework for modeling of heterogeneous objects in terms of trivariate B-spline functions and a method for slicing them directly for additive manufacturing. We first fit volumetric attribute data associated with the geometry in terms of trivariate B-spline functions under the assumption that the geometric volume is already defined by the trivariate B-spline functions. Then, the B-spline volume and the associated attribute data are directly sliced without converting them to stereo-lithography format, resulting in a tool path with fewer errors. Furthermore, adaptive ray shooting is introduced in the slicing plane so that the zigzag tool path passes through all the tangential intersection points of the heterogeneous objects to represent all the feature points in the fabricated model. Complex examples illustrate the effectiveness of our method.

Modeling of Heterogeneous Objects: An Approach Based on Implicit Functions

<p>El modelado de objetos, sus propiedades y relaciones es un tema importante en las ciencias de la computación y la informática. En ese sentido, esta investigación busca contribuir al modelado de objetos sólidos heterogéneos, así como al complejo estudio de la representación implícita de objetos sólidos. El enfoque que aquí se presenta es amplio y genérico, pero este artículo se centra en modelos bio-CAD, aludiendo su extensión y aplicación a otros campos. El objetivo general de este trabajo es demostrar que los modelos geométricos de objetos heterogéneos se pueden representar de forma implícita. Esto promete tener gran variedad de aplicaciones prácticas desde la computación biomédica hasta la animación por computador y la ingeniería aplicada. El enfoque adoptado aquí se basa en la observación de que los modelos sólidos actuales no pueden representar intrínsecamente información geométrica multifase junto con la información de los atributos. Esto hace necesario explorar nuevas técnicas de modelado para representar objetos del mundo real. La disponibilidad de este tipo de modelos es fundamental para el diseño, análisis y fabricación de objetos heterogéneos.</p>

Computer-aided design–computer-aided engineering associative feature-based heterogeneous object modeling

Conventionally, heterogeneous object modeling methods paid limited attention to the concurrent modeling of geometry design and material composition distribution. Procedural method was normally employed to generate the geometry first and then determine the heterogeneous material distribution, which ignores the mutual influence. Additionally, limited capability has been established about irregular material composition distribution modeling with strong local discontinuities. This article overcomes these limitations by developing the computer-aided design–computer-aided engineering associative feature-based heterogeneous object modeling method. Level set functions are applied to model the geometry within computer-aided design module, which enables complex geometry modeling. Finite element mesh is applied to store the local material compositions within computer-aided engineering module, which allows any local discontinuities. Then, the associative feature concept builds the correspondence relationship between these modules. Additionally, the level set geometry and material optimization method are developed to concurrently generate the geometry and material information which fills the contents of the computer-aided design–computer-aided engineering associative feature model. Micro-geometry is investigated as well, instead of only the local material composition. A few cases are studied to prove the effectiveness of this new heterogeneous object modeling method.

HiGeoM: A symbolic framework for a unified function space representation of trivariate solids for isogeometric analysis

In this paper, a procedural description of solids is proposed with representational domain that encompasses the needs in Computer Aided Design (CAD), heterogeneous object modeling and Computer Aided Engineering (CAE). Specifically, a function space formalism, that unifies the representation of geometry and physical attributes, is proposed along with an algebra that operates on elements in those spaces. A declarative programming language is provided, which accepts a subset of mathematical semantics specified using the Mathematical Markup Language (MathML) as well as a fortran-like syntax. The language enables a high-level definition of the geometric model using continuous affine transformation and boolean operators leading to a mixed-dimensional representation. Thus, it is possible to construct analytically defined shapes as well as spline representation of complex geometry. The framework is demonstrated by constructing complex engineered solids and isogeometrically solving boundary value problems on the constructed solid.

Heterogeneous object modeling with material convolution surfaces

The possibility to attain diverse applications from heterogeneous objects calls for a generic and systematic modeling approach for design, analysis and rapid manufacturing of heterogeneous objects. The available heterogeneous object modeling techniques model simple material-distributions only and just a few of them are capable of modeling heterogeneous objects with complex geometries. Even these approaches have also, at time, shown some glitches while modeling complex objects with compound and irregular material variations. This paper unfolds the development of a stand-alone convolution surface-based modeling approach to model complex heterogeneous objects with multi-functional heterogeneities, entailing stratified sub-analytic boundary-representation, convolution material primitives, membership functions and material-potential functions. One-dimensional (associative and non-associative) and compound two-and three-dimensional material-distribution schemas are formulated and outlined to model simple, compound and irregular material-distributions in simple/complex geometry objects. The paper also illustrates a few examples of modeling complex heterogeneous objects by implementing the approach using specialized languages and software tools.

Optimized normal and distance matching for heterogeneous object modeling

This paper presents a new optimization methodology of material blending for heterogeneous object modeling by matching the material-governing features. The proposed method establishes point-to-point correspondence represented by a set of connecting lines between two material directrices. To blend the material features between the directrices, a heuristic optimization method is developed to maximize the sum of the inner products of the unit normals at the end points of the connecting lines and minimize the sum of the lengths of the connecting lines. The geometric features with material information are matched to generate non-self-intersecting and non-twisted connecting surfaces. By subdividing the connecting lines into an equal number of segments, a series of intermediate piecewise curves is generated to represent the material metamorphosis between the governing material-features. A dynamic programming approach developed in our earlier work is presented for comparison purposes, and the computational efficiency of the proposed heuristic method is also compared with earlier techniques in the literature. Computer interface implementation and illustrative examples are also presented in this paper.

Heterogeneous object modeling using the radial basis functions

This paper presented an effective method for the three-dimensional (3D) heterogeneous objects modeling. First, an implicit solid representing the smooth 3D scalar field for the material property distribution was reconstructed by interpolating the geometric positions of control points and property values defined at those points using an implicit interpolation algorithm based on the thinplate radial basis function (RBF). After generating the implicit solid representing the smooth 3D scalar field for the material property distribution, a heterogeneous object model with accurately controlled material property distribution was designed using the generated implicit solid. A variety of experimental results showed that the proposed heterogeneous objects modeling method has the potential benefits for accurately controlling the spatial material property distribution within an arbitrarily-shaped geometrical model.

Object-space multiphase implicit functions

Implicit functions have a wide range of applications in entertainment, engineering and medical imaging. A standard two-phase implicit function only represents the interior and exterior of a single object. To facilitate solid modeling of heterogeneous objects with multiple internal regions, object-space multiphase implicit functions are much desired. Multiphase implicit functions have much potential in modeling natural organisms, heterogeneous mechanical parts and anatomical atlases. In this paper, we introduce a novel class of object-space multiphase implicit functions that are capable of accurately and compactly representing objects with multiple internal regions. Our proposed multiphase implicit functions facilitate true object-space geometric modeling of heterogeneous objects with non-manifold features. We present multiple methods to create object-space multiphase implicit functions from existing data, including meshes and segmented medical images. Our algorithms are inspired by machine learning algorithms for training multicategory max-margin classifiers. Comparisons demonstrate that our method achieves an error rate one order of magnitude smaller than alternative techniques.

An approach to representing heterogeneous non-uniform rational B-spline objects

The representation method of heterogeneous material information is one of the key technologies of heterogeneous object modeling, but almost all the existing methods cannot represent non-uniform rational B-spline (NURBS) entity. According to the characteristics of NURBS, a novel data structure, named NURBS material data structure, is proposed, in which the geometrical coordinates, weights and material coordinates of NURBS heterogeneous objects can be represented simultaneously. Based on this data structure, both direct representation method and inverse construction method of heterogeneous NURBS objects are introduced. In the direct representation method, three forms of NURBS heterogeneous objects are introduced by giving the geometry and material information of control points, among which the homogeneous coordinates form is employed for its brevity and easy programming. In the inverse construction method, continuous heterogeneous curves and surfaces can be obtained by interpolating discrete points and curves with specified material information. Some examples are given to show the effectiveness of the proposed methods.

Modeling of time-variant heterogeneous objects in micro-system packages

UBM (under bump metallurgy) of micro-system packages consists of several heterogeneous layers such as solder wetting, diffusion barrier, adhesion, and IMC (inter-metallic compound) layers. In particular, the IMC layer, formed between the solder wetting layer (e.g., Cu or Ni) and the solder, grows gradually and thus its composition changes with time (i.e., time-variant). The primary failure mechanism of the solder joints in micro-system packages is widely known as the fatigue failure caused by thermal fatigue and electro-migration damage. However, these phenomena have thus far been viewed from experimental investigations. Therefore, finite element analysis (FEA) becomes an important step for the optimal design and reliability analysis of heterogeneous objects such as in micro-system packages. However, the accuracy of the FEA wholly depends on the quality of finite element models. There thus exists an increasing need for generating finite element models adaptive to both geometric complexity and material distribution. In this sense, this paper presents a new method for modeling of time-variant heterogeneous objects such as in micro-system packages whose composition changes with time. Heterogeneous Boolean operators based on the diffusion process are proposed to construct time-variant heterogeneous objects. Once a time-variant heterogeneous solid model is constructed, it is then discretized into an object model onto which appropriate material properties are mapped. Discretization converts continuous material variations inside an object into stepwise variations. Next, the object model is adaptively meshed and converted into a finite element model. FEA using commercial software is finally performed to check failure criteria. An example (UBM in micro-system package) is shown to illustrate the entire modeling procedure.

THE DEVELOPMENT OF HETEROGENEOUS OBJECT DESIGN FOR RAPID PROTOTYPING

Rapid Prototype (RP) manufacturing has been widely used in many industries, including prototype fabrication, product assembly testing, mechanism interference testing, and rapid tooling. Researchers have been focusing on the RP applications for functional part fabrication in recent years. One of the most challenging research topics in RP is Rapid Prototype fabrication, particularly with graded material objects. Graded material means that the material's composition is changed according to the area of the object. The graded material object model includes the typical part geometric information and the heterogeneous material information that forms a more complicated object model. This research developed a heterogeneous object model, which was implemented on a software program. Results show that the heterogeneous model contains material grading information as well as geometry information. Two examples are included for the material composition distribution at the end of this paper.

Heat conduction analysis of heterogeneous objects based on multi-color distance field

The separation of computer aided design (CAD) modeling and finite element analysis (FEA) of heterogeneous objects makes it cumbersome for designers to exchange the data information. In this paper a systematic modeling and analysis for heterogeneous objects based on multi-color distance field was proposed. Firstly, the geometric model of an object was represented by the signed distance field; next, each grid was assigned with material property and material distance field which had the same resolution with geometric distance field was calculated according to material feature; the geometric and material distance fields were then unified, named as multi-color distance field. Then, through sampling the multi-color distance field, boundary and interior nodes were directly as nodes for meshless weighted least-square (MWLS) analysis. Using the moving least-squares approximation scheme as shape function, the MWLS analysis leads to a pure meshless analysis for heterogeneous objects. In the end, the effectiveness of the approach was illustrated by several numerical examples.

Heterogeneous Object Modeling Approach Based on ACIS and HOOPS

This paper deals with the background and significance of working on heterogeneous objects modeling and briefly introduces the architecture of ACIS and HOOPS and their corresponding functional modules. Based on inverse-distance weighting algorithm to determine the material composition within the object, the general approach to modeling the heterogeneous objects by using ACIS and HOOPS is introduced and demonstrated via some simple examples.