Analysing the natural resting aspects of a complex part

SUMMARY

This papers introduces a new approach to predicting the natural resting behaviour of a prismatic part of irregular cross-section. The methods proposed by Boothroyd et al. (1972) and Boothroyd and Ho (1977) were successful in analyzing parts with geometrically simple configurations, although empirical factors were used in the former case. For the past 16 years or so, however, no attempt has been made to analyze pans with complex shapes. Up to now, the study of the natural resting behaviour of complex shapes was conducted by approximating or simplifying the two stated methods. Considering the fact that most parts encountered in industry are not geometrically simple, this practice is the norm rather than the exception. The hypothesis presented in this paper proposes that the probability of apart coming to rest on any of its many feasible resting surfaces is directly proportional to the centroid solid angle and inversely proportional to the height of the centroid from that surface. No empirical factors are needed or assumed. Complex components, such as those with a displaced centre of gravity, can be analyzed thus. The proposed hypothesis is compared with Boothroyd's Energy Barrier Method. The predictions of the hypothesis and the empirical results of drop tests conducted on non-symmetrical (oblong) and symmetrical (T-shaped( prisms are consistent to within 7%. This is the first successful attempt in the analysis of the natural behaviour of components with a complex shape.

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Notes on contributors

B. K. A. NGOI

To whom correspondence should be addressed.