Open Design Optimization Platform (ODOP) - Coil spring design app; mechanical springs; compression spring, extension spring, torsion spring
Alerts specific to torsion springs.
Alert entry #T301
The moment at operating point 1 (M_1) is greater than the moment at operating point 2 (M_2).
Torsion spring moments are ordered from the smallest (free condition) to M_1 to M_2 to the largest (Max Safe). The Torsion Spring Moment - Deflection Diagram provides more detail on this point.
Resolve this alert by reducing the value of M_1 below the value of M_2.
It should also be possible to confirm that M_1 is in Free status, confirm that the constraint Stroke MIN is enabled with a greater-than-zero constraint level and then use the Search feature (menu Action : Search or Search button).
See also:
Alert entry #T302
Disabling default constraints is not recommended. Adjust the constraint value instead.
This alert is produced when constraints enabled by default are disabled. This alert can be also be produced for designs created and saved with older versions of the software. Specifically, constraints on Spring_Index were not enabled by default in older designs. If this alert is associated with Spring_Index on an older design, it may be ignored. Better yet, clear the alert by enabling MIN and MAX constraints on Spring_Index.
The default constraints guide Search to "good" spring designs. The Seek and Trade features utilize Search internally and thus those results are also guided by the default constraints.
For example:
In summary, while it may be reasonable to adjust the constraint values of a default constraint, disabling a default constraint entirely is not recommended.
Alert entry #T303
The second operating point (point 2) has more than 80% of maximum safe deflection. There may be some inaccuracy in moments and deflections for this point.
Even if the application requires that this design operate outside the range of 20% to 80% of available deflection, the inspection (acceptance) criteria should be specified within this range.
Helical coil compression, extension and torsion springs that have the properties of uniform pitch and cylindrical shape follow Hooke's Law in that they provide a nominally linear relationship between force (moment) and deflection. However, in the real world there are limitations.
When torsion springs are deflected beyond roughly 80% of safe deflection geometric imperfections such as a lack uniformity in coil pitch, minor deviation from cylindrical shape and deflection in the ends become factors in the real (as opposed to theoretical) moment-deflection relationship. Depending on Coil_Spacing, coil to coil contact may produce an increase in spring rate that continues to increase with additional deflection until the maximum safe operating condition is reached. Thus, when operating beyond 80% of the safe deflection, expect moments to be somewhat higher (or deflections to be somewhat lower) than the linear behavior predicted by the equations.
Specifying a small value for Coil_Spacing (available on Advanced View) can serve to reduce the influence of coil to coil contact.
See also:
Alert entry #T304
The first operating point (point 1) has less than 20% of maximum safe deflection. There may be some some inaccuracy in moment and deflection for this point.
Even if the application requires that this design operate outside the range of 20% to 80% of available deflection, the inspection (acceptance) criteria should be specified within this range.
Helical coil compression, extension and torsion springs that have the properties of uniform pitch and cylindrical shape follow Hooke's Law in that they provide a nominally linear relationship between force and deflection. However, in the real world there are limitations.
When torsion springs are deflected less than roughly 20% of maximum safe deflection, various factors such as deviation from perfect coil straightness (cylindrical form) and deflection in the ends will become a factor in the real (as opposed to theoretical) force-deflection relationship. Thus when operating within the first 20% of the available deflection expect moments to be somewhat lower (or deflections to be somewhat greater) than the linear behavior predicted by the equations.
See also: