Design Model Applied to the Design of Production Machines

This paper describes a general design model that serves as a base for computer-support in the conceptual design stage. The model consists of a model of the artefact to be designed, design activities and knowledge. The artefact model contains multiple views, each highlighting a certain aspect of the design. Design activities are performed to create this model and knowledge describes information generated in the past that can be reused. The general design model has been used to develop a specific model for the design of production machines. This specific model has been implemented in a prototype computer-program and has been evaluated within several companies. The results are promising and show that designers gain new insights by using the model.

Direct Method of Blank Determination in Stamping

Usually, the exact geometry of the blank of a stamping is obtained by successive corrections of a presupposed blank subjected to the operation of stamping or its simulation. This paper presents an innovating method of direct predetermination of the blank. The part is set flat that it gives the required part when subjected to the action of the tool for stamping. The setting flat presents splits and the part carried out some discontinuities. The setting flat is then deformed to reabsorb the splits and the shape thus obtained is the optimized blank. This method is illustrated and validated on a rectangular cup by a comparison between the calculated blank and the part obtained.

A Product Variety Tradeoff Evaluation Method for a Family of Cordless Drill Transmissions

In this paper we present the Product Variety Tradeoff Evaluation Method for assessment of alternative product platforms in product family design. The Product Variety Tradeoff Evaluation Method is an attention-directing tool for evaluating tradeoffs between commonality and individual product performance for product platform alternatives with differing levels of commonality. We apply the Product Variety Tradeoff Evaluation Method to a case study in transmission redesign for a family of cordless drills. The emphasis in this paper is placed on the method rather than on the results, per se.

Regions of Feasible Point-to-Point Trajectories in the Cartesian Workspace of Fully-Parallel Manipulators

The goal of this paper is to define the n-connected regions in the Cartesian workspace of fully-parallel manipulators, i.e. the maximal regions where it is possible to execute point-to-point motions. The manipulators considered in this study may have multiple direct and inverse kinematic solutions. The N-connected regions are characterized by projection, onto the Cartesian workspace, of the connected components of the reachable configuration space defined in the Cartesian product of the Cartesian space by the joint space. Generalized octree models are used for the construction of all spaces. This study is illustrated with a simple planar fully-parallel manipulator.

Smart Optimization of Machine Systems Using Hierarchical Genotype Representations

Design problems for machine products are generally hierarchically expressed. With conventional product optimization methods, it is difficult to concurrently optimize all design variables of portions within the hierarchical structure. This paper proposes a design optimization method using genetic algorithms containing hierarchical genotype representations, so that the hierarchical structures of machine system designs are exactly expressed through genotype coding, and optimization can be concurrently conducted for all of the hierarchical structures. Crossover and mutation operations for manipulating the hierarchical genotype representations are also developed. The proposed method is applied to a machine-tool structural design to demonstrate its effectiveness.

A Distributed Approach for Accessibility and Maintainability Check With a Manikin

The validation of the accessibility, maintainability, mounting/dismantle simulation in a cluttered environment is a key problem during the design process of a mechanical system. On the one hand research in path planning lead to automatic trajectory definition. These systems are really efficient for simple problems. On the other hand direct manipulation is possible thanks to robotic CAD systems. Another direct manipulation is possible with common virtual reality tools that allow the designer immersion in a whole mechanical environment. In such an environment the designer can handle an object in order to check its accessibility. Thanks to the use of a multi-agent architecture we greatly improve the effectiveness of virtual reality tools while coupling algorithmic approaches and direct manipulation. This original method is a solution of a multi-criteria constrained optimisation problem. Theoretical and practical aspects are presented.

Fictitious Domain Solution of Frequency Response Problems

This paper discusses an alternative solution strategy for frequency response problems in elasticity. This strategy uses a meshless method, derived in a periodic domain setting, extended to allow the analysis of arbitrary geometries with the use of a fictitious domain. This solution technique is designed to solve problems with a large number of degrees of freedom and it requires the use of iterative solvers where preconditioning is necessary for reasonable convergence rates. Two dimensional examples illustrating this approach are provided.

A Model for the Prediction of Form Errors in Face Milling and Turning

A method is proposed for predicting form errors due to both clamping and cutting forces in face milling and turning. It allows complex tool trajectories and workpiece geometries. Error computation is performed by the finite element method. An experimental validation of the model for face milling is presented. Two industrial applications are produced in order to demonstrate the capabilities of the method.

Topology Synthesis of Large-Displacement Compliant Mechanisms

This paper describes the use of topology optimization as a synthesis tool for the design of large-displacement compliant mechanisms. An objective function for the synthesis of large-displacement mechanisms is proposed together with a formulation for synthesis of path-generating compliant mechanisms. The responses of the compliant mechanisms are modelled using a Total Lagrangian finite element formulation, the sensitivity analysis is performed using the adjoint method and the optimization problem is solved using the Method of Moving Asymptotes. Procedures to circumvent some numerical problems are discussed.

Comparison of Two Multiobjective Optimization Techniques With and Within Genetic Algorithms

Engineering decision making involving multiple competing objectives relies on choosing a design solution from an optimal set of solutions. This optimal set of solutions, referred to as the Pareto set, represents the tradeoffs that exist between the competing objectives for different design solutions. Generation of this Pareto set is the main focus of multiple objective optimization. There are many methods to solve this type of problem. Some of these methods generate solutions that cannot be applied to problems with a combination of discrete and continuous variables. Often such solutions are obtained by an optimization technique that can only guarantee local Pareto solutions or is applied to convex problems. The main focus of this paper is to demonstrate two methods of using genetic algorithms to overcome these problems. The first method uses a genetic algorithm with some external modifications to handle multiple objective optimization, while the second method operates within the genetic algorithm with some significant internal modifications. The fact that the first method operates with the genetic algorithm and the second method within the genetic algorithm is the main difference between these two techniques. Each method has its strengths and weaknesses, and it is the objective of this paper to compare and contrast the two methods quantitatively as well as qualitatively. Two multiobjective design optimization examples are used for the purpose of this comparison.