Research Papers

J. Comput. Inf. Sci. Eng. 2017;17(3):031001-031001-9. doi:10.1115/1.4034737.

In the geometric simulation of multi-axis milling, a dexel representation solid model is frequently used. In this modeling method, the object shape is defined as a collection of vertical segments (dexels) based on a two-dimensional regular square grid in the XY plane. In this paper, the authors propose the quad pillars algorithm and its enhanced version named the delta pillars algorithm for converting a dexel model to an equivalent polyhedral stereolithography (STL) model. These algorithms define a series of vertical pillar shapes for each square cell of the grid to represent the object shape as a bundle of pillars. The final polyhedral model is obtained by performing a simplified Boolean union operation of the pillar shapes. Unlike prior methods, the proposed algorithms are simple and fast and are guaranteed to generate a watertight polyhedral model without holes, gaps, or T-junctions. An experimental system is implemented and conversion tests are performed. The system converted a dexel model based on a high-resolution grid to a polyhedral model in a practical amount of time.

Commentary by Dr. Valentin Fuster
J. Comput. Inf. Sci. Eng. 2017;17(3):031002-031002-16. doi:10.1115/1.4035673.

New business models and more integrated product development processes require designers to make use of knowledge more efficiently. Capture and reuse are means of coping, but support, techniques, and mechanisms have yet to be sufficiently addressed. This paper consequently explores how computer-aided technologies (CAx) and a computer-aided design (CAD) model-oriented approach can be used to improve the efficiency of design module capture and representation for product family reuse. The first contribution of this paper is the investigation performed at a Swedish manufacturing company and a set of identified challenges related to design capture and representation for reuse in product family development. The second contribution is a demonstrated and evaluated set of systems and tools, which exemplifies how these challenges can be approached. Efficient design capture is achieved by a combination of automated and simplified design capture, derived from the design implementation (CAD model definition) to the extent possible. Different design representations can then be accessed by the designer using the CAD-internal tool interface. A web application is an example of more general-purpose representation to tailor design content, all of which is managed by a product lifecycle management (PLM) system. Design capture is based on a modular view block definition, stored in formal information models, management by a PLM system, for consistent and reliable design content. It was, however, introduced to support the rich and expressive forms of capture and representation required to facilitate understanding, use, and reuse of varied and increasingly complex designs. A key element in being able to describe a complex design and its implementation has been capture and representation of a set of design states. The solution has been demonstrated to effectively be able to capture and represent significant portions of a step-by-step design training material and the implementation of complex design module through a set of design decisions taken. The validity and relevance of the proposed solution is strengthened by the level of acceptance and perceived value from experienced users, together with the fact that the company is implementing parts of it today.

Commentary by Dr. Valentin Fuster
J. Comput. Inf. Sci. Eng. 2017;17(3):031003-031003-10. doi:10.1115/1.4035674.

A competition for teams of three students using a prototype multi-user computer-aided design (MUCAD) tool was held to investigate various hypotheses regarding the performance of teams in such a setting. By comparing models from the competition to the same model in a single-user CAD environment, it is seen that use of a MUCAD system can significantly increase the value-added per unit of calendar time for a modeling effort. An investigation was also made into the causes of the performance differences among the various MUCAD teams which participated in the competition. Analysis of the results shows that teams that encouraged effective forms of communication and teams whose members scored similarly on the Purdue Spatial Visualization Test: Visualization of Rotations (PSVT:R) performed better than other teams. Areas of future research in analyzing teams in MUCAD environments are suggested.

Commentary by Dr. Valentin Fuster
J. Comput. Inf. Sci. Eng. 2017;17(3):031004-031004-6. doi:10.1115/1.4034740.

This paper presents the design process of a novel general-purpose electric vehicle chassis as agriculture payload carrier platform to perform agricultural tasks: detection, guidance, mapping, and action. This design applied a human-centered design frameworks and processes: Kumar's seven modes of the design innovation process, and the three lenses of human-centered design by IDEO. After approach from three design-project perspectives mapping, a universal electric-powered multiwheel independent drive and independent steering robotic vehicle platform is designed for agricultural application. A real size prototype has been built to prove the design.

Commentary by Dr. Valentin Fuster
J. Comput. Inf. Sci. Eng. 2017;17(3):031005-031005-4. doi:10.1115/1.4034742.

This paper presents a design process of a novel electric wheelchair controller to enable a dual control access for both the users in the wheelchair and their caregivers. This design applied human-centered design frameworks, processes, and tools: Kumar's seven modes of the design innovation process and IDEO, Palo Alto, CA, design method cards. After such design process, a design of dual control access controller of an electric wheelchair is established. A real-size prototype has been built to prove the design concept; and further, the method of control switching between people in and behind the wheelchair has been optimized with the established prototype.

Commentary by Dr. Valentin Fuster
J. Comput. Inf. Sci. Eng. 2017;17(3):031006-031006-9. doi:10.1115/1.4033994.

The improvement and the massive diffusion of additive manufacturing (AM) techniques have fostered the research of design methods to exploit at best the feature introduced by these solutions. The whole design paradigm needs to be changed taking into account new manufacturing capabilities. AM is not only an innovative method of fabrication, but it requires a new way to design products. Traditional practices of mechanical design are changing to exploit all potential of AM, new parameters and geometries could be realized avoiding technologies constrains of molding or machine tooling. The concept of “manufacturing for design” increasingly acquires greater importance and this means we have the chance to focus almost entirely on product functionality. The possibility to confer inhomogeneous properties to objects provides an important design key. We will study behavior and structure according to desired functions for each object identifying three main aspects to vary: infill type, external topology and shape, and material composition. In this research work, we focus on fused deposition modeling (FDM) technology of three dimensional (3D) printing that easily allows to explore all previous conditions. We present a new way to conceive design process in order to confer variable properties to AM objects and some guidelines to control properties of deformation and elasticity using classic infills. The ultimate aim is to apply new design rules provided by AM in the prosthetic field of lower limb amputees. The socket of the prosthesis represents a deformable interface between the residual limb and the artificial leg that must be optimized according to geometry and loads distribution of patient. An application for a transfemoral patient will be discussed.

Commentary by Dr. Valentin Fuster
J. Comput. Inf. Sci. Eng. 2017;17(3):031007-031007-14. doi:10.1115/1.4035675.

Energy consumption in manufacturing has risen to be a global concern. Material selection in the product design phase is of great significance to energy conservation and emission reduction. However, because of the limitation of the current life-cycle energy analysis and optimization method, such concerns have not been adequately addressed in material selection. To fill in this gap, a process to build a comprehensive multi-objective optimization model for automated multimaterial selection (MOO–MSS) on the basis of cloud manufacturing is developed in this paper. The optimizing method, named local search-differential group leader algorithm (LS-DGLA), is a hybrid of differential evolution and local search with the group leader algorithm (GLA), constructed for better flexibility to handle different needs for various product designs. Compared with a number of evolutionary algorithms and nonevolutionary algorithms, it is observed that LS-DGLA performs better in terms of speed, stability, and searching capability.

Commentary by Dr. Valentin Fuster
J. Comput. Inf. Sci. Eng. 2017;17(3):031008-031008-13. doi:10.1115/1.4034436.

Engineering design is increasingly recognized as a decision making process. Providing decision support is crucial to augment designers' decision-making capability in this process. In this paper, we present a template-based ontological method that integrates the decision-making mechanism with problem-specific information; thus, it can provide design decision support from both the “construct” and the “information” perspectives. The “construct,” namely, decision-making mechanism, is the utility-based Decision Support Problem (u-sDSP), which is a rigorous mathematical model that facilitates designers making multi-attribute selection decisions under uncertainty, while the information for decision making is archived as u-sDSP templates and represented using frame-based ontology to facilitate reuse, execution, and consistency-maintaining. This paper is an extension of our earlier work on the ontological modeling of the compromise decisions. The unique advantage of this ontology is that it captures both the declarative and procedural knowledge of selection decisions and represents them separately, thus facilitating designers reusing, executing previous documented decision knowledge to effect new decisions. The efficacy of ontology is demonstrated using a rapid prototyping (RP) resource selection example.

Commentary by Dr. Valentin Fuster
J. Comput. Inf. Sci. Eng. 2017;17(3):031009-031009-11. doi:10.1115/1.4034387.

Freehand sketching is an integral part of early design process. Recent years have seen an increased interest in supporting sketching in computer-based design systems. In this paper, we present finite element analysis made easy (FEAsy), a naturalistic environment for static finite element analysis. This tool allows users to transform, simulate, and analyze their finite element models quickly and easily through freehand sketching. A major challenge here is to beautify freehand sketches, and to this extent, we present a domain-independent, multistroke, multiprimitive method which automatically detects and uses the spatial relationships implied in the sketches for beautification. Further, we have also developed a domain-specific rules-based algorithm for recognizing commonly used symbols in finite element analysis (FEA) and a method for identifying different contexts in finite element modeling through combined interpretation of text and geometry. The results of the user study suggest that our proposed algorithms are efficient and robust. Pilot users found the interface to be effective and easy to use.

Commentary by Dr. Valentin Fuster
J. Comput. Inf. Sci. Eng. 2017;17(3):031010-031010-9. doi:10.1115/1.4035001.

With design teams becoming more distributed, the sharing and interpreting of complex data about design concepts/prototypes and environments have become increasingly challenging. The size and quality of data that can be captured and shared directly affects the ability of receivers of that data to collaborate and provide meaningful feedback. To mitigate these challenges, the authors of this work propose the real-time translation of physical objects into an immersive virtual reality environment using readily available red, green, blue, and depth (RGB-D) sensing systems and standard networking connections. The emergence of commercial, off-the-shelf RGB-D sensing systems, such as the Microsoft Kinect, has enabled the rapid three-dimensional (3D) reconstruction of physical environments. The authors present a method that employs 3D mesh reconstruction algorithms and real-time rendering techniques to capture physical objects in the real world and represent their 3D reconstruction in an immersive virtual reality environment with which the user can then interact. Providing these features allows distributed design teams to share and interpret complex 3D data in a natural manner. The method reduces the processing requirements of the data capture system while enabling it to be portable. The method also provides an immersive environment in which designers can view and interpret the data remotely. A case study involving a commodity RGB-D sensor and multiple computers connected through standard TCP internet connections is presented to demonstrate the viability of the proposed method.

Commentary by Dr. Valentin Fuster
J. Comput. Inf. Sci. Eng. 2017;17(3):031011-031011-11. doi:10.1115/1.4035528.

This paper studies the problem of planar four-bar motion generation from the viewpoint of extraction of geometric constraints from a given set of planar displacements. Using the image space of planar displacements, we obtain a class of quadrics, called generalized- or G-manifolds, with eight linear and homogeneous coefficients as a unified representation for constraint manifolds of all four types of planar dyads, RR, PR, and PR, and PP. Given a set of image points that represent planar displacements, the problem of synthesizing a planar four-bar linkage is reduced to finding a pencil of G-manifolds that best fit the image points in the least squares sense. This least squares problem is solved using singular value decomposition (SVD). The linear coefficients associated with the smallest singular values are used to define a pencil of quadrics. Additional constraints on the linear coefficients are then imposed to obtain a planar four-bar linkage that best guides the coupler through the given displacements. The result is an efficient and linear algorithm that naturally extracts the geometric constraints of a motion and leads directly to the type and dimensions of a mechanism for motion generation.

Commentary by Dr. Valentin Fuster
J. Comput. Inf. Sci. Eng. 2017;17(3):031012-031012-10. doi:10.1115/1.4036552.

Spatial variation of material structures is a principal mechanism for creating and controlling spatially varying material properties in nature and engineering. While the spatially varying homogenized properties can be represented by scalar and vector fields on the macroscopic scale, explicit microscopic structures of constituent phases are required to facilitate the visualization, analysis, and manufacturing of functionally graded material (FGM). The challenge of FGM structure modeling lies in the integration of these two scales. We propose to represent and control material properties of FGM at macroscale using the notion of material descriptors, which include common geometric, statistical, and topological measures, such as volume fraction, correlation functions, and Minkowski functionals. At microscale, the material structures are modeled as Markov random fields (MRFs): we formulate the problem of design and (re)construction of FGM structure as a process of selecting neighborhoods from a reference FGM, based on target material descriptors fields. The effectiveness of the proposed method in generating a spatially varying structure of FGM with target properties is demonstrated by two examples: design of a graded bone structure and generating functionally graded lattice structures with target volume fraction fields.

Commentary by Dr. Valentin Fuster

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