Product Shape Design Research Articles

A nurbs finite element method for product shape design

In a design of industrial product, its shape that influences the rigidity and vibratory characteristics as well as productivity is determined by trial-and-error-based experimentation or simulation. The NURBS representation is used widely in computer-aided design/computer-aided manufacturing (CAD/CAM) systems because it offers good capabilities for representation of sculptured surfaces, reduction of the amount of numerical control data, and control of the cutter pass and cutting speed. Thereby, it realizes a smooth surface and high efficiency of manufacturing. Therefore, once a finite element method based on the NURBS representation is established, we may integrate it into a comprehensive CAD/CAM/computer-aided engineering tool for product design. From that point of view, this study addresses the formulation of a finite shell element that perfectly forms the product shape represented by the NURBS surface. The NURBS surface, which is originally defined by a control point scheme, is represented by interpolating the nodal points on the surface. The function for this interpolation is used for the shape function. The explicit derivation of the shape function also allows formation of a mass matrix to solve dynamic problems. The method presented here is applied to several bending analyses of plates and shells to demonstrate the effectiveness and good accuracy of the method. Results suggest that this method offers a useful tool for product shape design.

Freeform shape variables of product designs and their correlation to subjective criteria

Compared to other parameters in product design, visually relevant shape parameters strongly determine the success of a product in the market. Since designers are responsible for the visual appearance of the product, they tend to be critical in their decisions concerning the type and the values of the shape parameters. However, it is not fully understood how the relevant parameters types can be determined and what the effect of their variation is. In two experiments, shape parameters were manipulated and customers indicated their preferred setting using different experimental paradigms. These preference scores may be considered to represent the judgement of aesthetic quality by potential customers. The results clearly show that preference as function of shape parameters can be determined. A method for shape deformation, and suggestions concerning possible improvements and applications are reported. When a large group of respondents can be involved in the assessments, using a web based tool, the method can be effective in conceptual product shape design.

Curve interpolation based on Catmull-Clark subdivision scheme*

Abstract An efficient algorithm for curve interpolation is proposed. The algorithm can produce a subdivision surface that can interpolate the predefined cubic B-spline curves by applying the Catmull-Clark scheme to a polygonal mesh containing symmetric zonal meshes which possesses some special properties. Many kinds of curve interpolation problems can be dealt with by this algorithm such as interpolating single open curve or closed curve a mesh of nonintersecting or intersecting curve. The interpolating surface is C 2 everywhere excepting at a finite number of points. At the same time, sharp creases can also be modeled on the limit subdivision surface by duplicating the vertices of the tagged edges of initial mesh.i. e. the surface is only C 0 along the cubic B-spline curve that is defined by the tagged edges. Because of being simple and easy to implement, this method can be used for product shape design and graphic software development.

A preliminary study on qualitative and imprecise solid modelling for conceptual shape modelling

The shape design of products is the primary activity of design process. A preliminary study on qualitative and imprecise solid modelling for computer-aided conceptual shape design is presented in this paper. Firstly, the requirements of shape representation for computer-aided conceptual shape design are discussed. Secondly, in the situation where the product information is deficient, the ideas of qualitative and imprecise solid modelling are proposed to deal with qualitative and imprecise information of conceptual shapes. The aim is mainly to explore the representation and manipulation of product shapes in order to benefit designers to design shapes in the conceptual design phase. Finally, a prototype system called deficient information modelling system for conceptual shape (DIMShape) is under development to verify the relevant ideas.

Multi-sensory user interface for a virtual-reality-based computeraided design system

The generation of geometric shapes called ‘geometric concept designs’ via the multi-sensory user interface of a virtual reality (VR) based system motivates the current research. In this new VR-based system, geometric designs can be more effectively inputted into the computer in a physically intuitive way. The interaction mechanism is similar to the way in which industrial designers sit and discuss concept design shapes across a table from each other, prior to making a final decision about the product details. By using different sensory modalities, such as voice, hand motions and gestures, product designers can convey design ideas through the VR-based computer-aided design (CAD) system. In this scenario, the multi-sensory interface between human and computer plays a central role with respect to usability, usefulness and accuracy. The current paper focuses on determining the requirements for the multi-sensory user interface and assessing the applications of different input and output mechanisms in the virtual environment (VE). In order to evaluate this multi-sensory user interface, this paper formulates the typical activities in product shape design into a set of requirements for the VR-CAD system. On the basis of these requirements, we interviewed typical CAD users about the effectiveness of using different sensory input and output interaction mechanisms such as visual, auditory and tactile. According to the results of these investigations, a nodal network of design activity that defines the multi-sensory user interface of the VR-CAD system is determined in the current research. The VR-CAD system is still being developed. However, voice command input, hand motion input, three-dimensional visual output and auditory output have been successfully integrated into the current system. Moreover, several mechanical parts have been successfully created through the VR interface. Once designers use the VR-CAD system that we are currently developing, the interface requirements determined in the current paper may be verified or refined. The objectives of the current research are to expand the frontiers of product design and establish a new paradigm for the VR-based conceptual shape design system.