Best Fit Product - Emotional Engineering - page 34

case of development of sports shoes, it is a challenge against short term degradation
and it should also be stressed that it is a problem of short term break-in or adap-
tation. Although the importance of these issues is well recognized by such indus-
tries as sport shoes developers, etc., researches relating to these issues are still very
few. These shoes industries are developing their products by trials and errors.
12.1 Fatigue
One of the most typical degradation is fatigue. Fatigue is studied only from the
standpoint of failure and its prevention. S - N curve only represents stress versus
number of cycles to failures. But this curve represents the response of material to
stress so if we could establish another curve that describes relation between
adaptability and number of cycles, we could estimate the necessary time for
breaking in and if we could maintain the condition as long as possible, we could
maintain the feeling of best ! fit for a longer time. We should pursue such degradation
phenomenon as fatigue from completely different standpoint, i.e., the standpoint of
adaptability. This is the problem of long term adaptation.
12.2 Traditional Maintenance and Adaptive Maintenance
Maintenance in the traditional sense has been to restore the degrading function back
to its design level. But maintenance proposed here means to keep the best ! t
condition as long as possible (Fig. 4 ) .
If we can control degradation appropriately, we can keep the feeling of best ! t
and enjoy using our products much longer, because we can use our products in their
best working condition in spite of the widely and frequently changes of situations
and environments. Further, we can avoid producing too many and too wide variety
of products. Then, we can reduce energy consumption, time and cost.
Fig. 4 Adaptive maintenance