Implicit Function Alteration via Radius Mapping and Direct Function Modification

In this paper, we present two closely related techniques, radius mapping, and direct function modification, that allow for the alteration of both the major geometry and surface features of implicit solids. The first technique, radius mapping, is applied to implicit functions generated by swept solid techniques. A more generalized technique, direct function modification, allows for the mapping of generalized function modifiers onto any implicit solid. Both the radius functions and the function modifiers can be either algebraic or non-algebraic in nature. Techniques for generating both algebraic and non-algebraic radius functions and function modifiers are given along with several examples of their use on both swept solids and implicit functions.

A Genetic Algorithm for Scheduling and Decomposition of Multidisciplinary Design Problems

Complex engineering studies typically involve hundreds of analysis routines and thousands of variables. The sequence of operations used to evaluate a design strongly affects the speed of each analysis cycle. This influence is particularly important when numerical optimization is used, because convergence generally requires many iterations. Moreover, it is common for disciplinary teams to work simultaneously on different aspects of a complex design. This practice requires decomposition of the analysis into subtasks, and the efficiency of the design process critically depends on the quality of the decomposition achieved. This paper describes the development of software to plan multidisciplinary design studies. A genetic algorithm is used, both to arrange analysis subroutines for efficient execution, and to decompose the task into subproblems. The new planning tool is compared with an existing heuristic method. It produces superior results when the same merit function is used, and it can readily address a wider range of planning objectives.

Optimization Methods for Calculating Design Imprecision

The preliminary design process is characterized by imprecision: the vagueness of an incomplete design description. The Method of Imprecision uses the mathematics of fuzzy sets to explicitly represent and manipulate imprecise preliminary design information, enabling the designer to explore the space of alternative designs in the context of the designer and customer’s preferences among alternatives. This paper introduces new methods to perform Method of Imprecision calculations for general non-monotonic design evaluation functions that address the practical necessity to minimize the number of function evaluations. These methods utilize optimization and experiment design.

On the Optimal Robot Manipulator Motion Planning for Solid Freeform Fabrication by Thermal Spraying

A novel approach to optimal robot manipulator motion planning for Solid Freeform Fabrication (SFF) by thermal spraying is presented. In this approach, given the desired spatial geometry of the object, the motion of the spray gun relative to a forming platform is synthesized for minimal masking requirements considering the probabilistic nature of the thermal spraying process. The material build-up rate can be planned to achieve the desired distribution of the physical/material properties within the object volume. Examples of optimal motion planning for the generation of some basic solid objects and computer simulation of the effectiveness of the developed methodology are presented.

Stiffened CFRP-Panels Under Buckling Loads: Modeling, Analysis, Optimization

The present paper addresses the optimal layout of stiffened fiber composite plates (Fig. 1) considering buckling constraints; these plates are increasingly applied in many fields of engineering (air- and spacecraft technology, automotive industries, boatbuilding etc.). This particular area of structural optimization still requires substantial investigations into its fundamentals. The structural analysis alone for the treatment of this type of problems may increase to such a degree that the complete optimization process requires extremely long computation times due to the processing of a high amount of data, a fact that calls for the development of “intelligent” procedures in order to reduce the computation effort to a tolerable measure and to maintain reduplicability of the whole process. For this purpose, a so-called “constructive design model” is introduced.

An Object-Oriented Approach to the Engineering Design Process

Laboratory of Machine Design at the University of Oulu has modelled the production information for a gear transmission unit in co-operation with a Finnish gear manufacturer, Santasalo Ltd. The basic idea was to integrate computer aided design into modern FMS-based production activities. The main goal in this project is to capture the whole gear box development process from customer requirements to manufacturable assembly and detail information in OOA models.

A Framework for Component Layout and Geometry Design of Mechanical Systems: Configuration Network and its Viewing Control

A Framework of computational design method and model is proposed for layout and geometry design of complicated mechanical systems, which is named “configuration network and its viewing control”. In the method, a design object is represented with a set of declarative relationships among various elements of a system, that is, configurations, which is gradually extended from schematic structure to exact layout and geometry through design process. Since a whole of such configurations forms a too complicated network to compute all together, how to view subparts is controlled based on levels of granularity and width of scope range. Such a configuration network is made to grow and refined through embodying geometry and layout corresponding to a focused subpart with a numerical optimization procedure. The framework has also an ability to flexibly integrate with engineering analysis. Moreover, a design system is implemented with an object-oriented programming technique, and it is applied to a design problem of air conditioner units in order to show the validity and effectiveness of the framework.

Domains of Interference Between Working Bodies in Mechanisms and Manipulators

Criteria for the set of all points in a pair of working bodies in a mechanism or manipulator that can coincide for any kinematically admissible configuration of the underlying mechanism, called the domain of interference between the bodies, are formulated. Kinematic equations for the mechanism and parameterizations of the domains of the working bodies are used to derive analytical criteria for domains of interference. Three complementary problems are formulated and analyzed to characterize (1) the set of points in one of the interfering bodies that are occupied by any point in the second body, (2) the set of points in one of the interfering bodies that are occupied by any point on the boundary of the second body, and (3) the set of all points in space that are simultaneously occupied by points in the interfering bodies; each condition occurring for any kinematically admissible configuration of the mechanism. Analytical criteria for the boundaries of domains of interference for each of the three problems arc derived, based on row-rank deficiency of a sub-Jacobian matrix associated with the kinematic equations for each of the problems. Numerical methods for mapping boundaries of domains of interference are presented and illustrated for planar Stewart platforms with domes attached that are characteristic of flight or ground vehicle simulators.

A Study on Optimum Design Using Fuzzy Numbers As Design Variables

In this study, we summerize the method of fuzzy optimization using fuzzy numbers as design variables. In order to detect flaw in fuzzy calculation, we use LR-fuzzy numbers, which is known as its simplicity in calculation. We also use simple fuzzy numbers’ operations, which was proposed in the previous papers. The proposed method has unique characteristics that we can obtain fuzzy sets in design variables (results of the design) directly from single numerical optimizing process. Which takes a large number of numerical optimizing processes when we try to obtain similar results in the conventional methods. In the numerical examples, we compare the proposed method with several other methods taking imprecision in design parameters into account, and demonstrate the effectiveness of the proposed method.

A Rapid Recursive Experimental Approach to Structure/Control Re-Design

This paper introduces an experimental recursive method for simultaneously changing both the mechanical structure and control design of mechatronic systems in order to improve the system’s overall performance. The method improves a system’s closed-loop control specifications through recursive concurrent structure reinforcement and control gain optimization. By using a process of structural reinforcement, a single prototype structure can be used repeatedly until the system performance goals are achieved. To determine the optimal incremental structure changes, a recursive algorithm based on a gradient descent method and a parameter estimation theory is employed. After the incremental structure reinforcements are applied, the control parameters are optimized with respect to multiple control specifications. Next, the resulting system incorporating the structure and control changes is tested and compared with the desired level of performance. The entire process consisting of experimental evaluation, data analysis, and structure reinforcement is repeated until the system performance achieves the desired level. Simulation experiments are successful in changing both the structural and control parameters of a simplified positioning system and show improvement in the system’s overall settling time.