关键词: 组合体尺寸标注, 渐进式, 分形, 建导, 迭代规则

Abstract: Composite solid dimensioning is of great significance and difficulty in engineering
graphics teaching. A progressive fractal facilitation teaching method is proposed based on the
coherence of dimensioning and the shape decomposition of composite solid. The fractal facilitation
method is employed in each step to decompose the complicated composite solid into simple one,
through the progressive teaching method by means of taking into account the similarity of geometric
solid. The iteration rule for the fractal facilitation method of dimensioning can be referred to as
decomposing, shaping, locating and merging, which is corresponding to steps of decomposing the
composite solid, ascertaining the number of shape size, ensuring the number of location size, and
merging the repetition sizes. Three principles of dimensioning de-duplication have to be identified,
and the fractal facilitation method for dimensioning is applied, in terms of different composite solids.
The application of the progressive fractal facilitation method of dimensioning can take full advantage
of the similarity of geometric solid, and lead students to accomplish the dimensioning of composite
solid gradually, thus attaining a correct and complete dimensioning of composite solid.

Key words: dimensioning for composite solid, progressive, fractal, facilitation, iteration rule