Is a MSC Adams simulation with smaller steps always more reliable?

Question

In a given simulation in MSC Adams, if I use a 1 or 0.1 step increment, I get the (favorable) result I intuitively assumed would occur, but if I use step increments of 0.01 or 0.001 a different (and unfavorable) result occurs. One would assume the finer-detailed result would generate fewer simulation false-result-inducing artifacts. Should I always assume the more granular simulation will result the more realistic and reliable result?

NMech · Accepted Answer

This is a common issue on all numerical methods (not just multibody problems), i.e. the tradeoff between the following three types of error:

Round off error
Discretization
Truncation (sometimes the 2 and 3 are included in the same term).

All of them are forms of quantization error.
These three types have a dependence on mesh size (either spatial or temporal). You can see their dependence, in the following image.

As you reduce the time step (or mesh size) the discretization error decreases, however then what happens is that you get the round off error to increase. Usually, it's the balance between those two that dominates the total error.

Is a MSC Adams simulation with smaller steps always more reliable?

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