## Abstract

The technological competition has demanded an ever increasing technological development, and in e.g. design of airplanes and cars engineers use very sophisticated Finite Element models to simulate the real behaviour of the structures. The Finite Element models often uses highly sophisticated material models extending the elastic behaviour into plasticity/ rupture and/or including timedependent effects. This has great importance especially in hazardous load cases such as crash testing cars.

However in many other products the major emphasize is put on the service capabilities of the structure, and the risk of fatigue or reduced comfort dictates the design. In this respect the central point in design is to avoid that any material point leaves the elastic regime. This can often be a troublesome task especially in geometrically complicated designs such as pumps, compressors or gears. The design problem in these geometrically complicated situations is to find a suitable geometry which both secures that the design meets the stress requirements and the productions requirements in e.g. relation to the casting process.

Even in modern Finite Element systems the designer can not always find all the features he may wish. A way to solve the initial design problem namely finding a form can be solved by so-called topology optimization. The idea is to define a design region and an amount of material. The loads and supports are also fidefined, and the algorithm finds the optimal material distribution. The objective function dictates the form, and the designer can choose e.g. maximum stiness, maximum allowable stresses or maximum lowest eigenfrequency.

The result of the topology optimization is a relatively coarse map of material layout. This design can be transferred to a CAD system and given the necessary geometrically refinements, and then remeshed and reanalysed in other to secure that the design requirements are met correctly. The output of standard topology optimization has seldom well-defined, sharp contours leaving the designer with a tedious interpretation, which often results in less optimal structures. In the paper a new filtering technique is discussed, and it is demonstrated by examples that the topology layout results in very sharp contours.

The paper also deals with methods for securing production requirements primarily in connection with casting. The production process limits the design space as voids can not be accepted. The new filtering technique is also discussed in relation to eigenfrequency calculations.

Originalsprog | Engelsk |
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Titel | NAFEMS 4th Nordic Seminar Proceedings |

Antal sider | 7 |

Forlag | NAFEMS |

Publikationsdato | 2007 |

Sider | 1-7 |

Status | Udgivet - 2007 |

Begivenhed | NAFEMS - Nordic Seminar - Oslo, Norge Varighed: 20 mar. 2007 → 21 mar. 2007 Konferencens nummer: 4 |

### Konference

Konference | NAFEMS - Nordic Seminar |
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Nummer | 4 |

Land/Område | Norge |

By | Oslo |

Periode | 20/03/2007 → 21/03/2007 |

## Emneord

- Optimering
- materialeoptimering
- opologioptimering