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massProps

The massProps package extends rollupTree with functions to recursively calculate mass properties (and optionally, their uncertainties) for arbitrary composition trees. Formulas implemented are described in a technical paper published by the Society of Allied Weight Engineers.(Zimmerman and Nakai 2005)

Installation 

install.packages("massProps")

You can install the development version of massProps from GitHub with:

# install.packages("pak")
pak::pak("jsjuni/massProps")

Example

Suppose we have the following mass properties table:

library(massProps)
test_table
#>     id parent mass Cx Cy Cz Ixx  Ixy   Ixz Iyy   Iyz Izz POIconv Ipoint
#> 1  A.1          NA NA NA NA  NA   NA    NA  NA    NA  NA       -  FALSE
#> 2  A.2    A.1   NA NA NA NA  NA   NA    NA  NA    NA  NA       -  FALSE
#> 3  A.3    A.1   NA NA NA NA  NA   NA    NA  NA    NA  NA       -  FALSE
#> 4  C.1    A.1    5  0  0  0  80 -4.0 -24.0  80 -24.0  75       -  FALSE
#> 5  P.1    A.2    2  1  1  1   4 -0.1  -0.1   4   0.1   4       -  FALSE
#> 6  P.2    A.2    2  1  1 -1   4 -0.1  -0.1   4   0.1   4       -  FALSE
#> 7  P.3    A.2    2  1 -1  1   4 -0.1  -0.1   4   0.1   4       -  FALSE
#> 8  P.4    A.2    2  1 -1 -1   4 -0.1  -0.1   4   0.1   4       -  FALSE
#> 9  P.5    A.3    2 -1  1  1   4 -0.1  -0.1   4   0.1   4       -  FALSE
#> 10 P.6    A.3    2 -1  1 -1   4 -0.1  -0.1   4   0.1   4       -  FALSE
#> 11 P.7    A.3    2 -1 -1  1   4 -0.1  -0.1   4   0.1   4       -  FALSE
#> 12 P.8    A.3    2 -1 -1 -1   4 -0.1  -0.1   4   0.1   4       -  FALSE

and this graph with edges representing child-parent relations:

library(igraph)
E(test_tree)
#> + 11/11 edges from d76039e (vertex names):
#>  [1] A.2->A.1 A.3->A.1 C.1->A.1 P.1->A.2 P.2->A.2 P.3->A.2 P.4->A.2 P.5->A.3
#>  [9] P.6->A.3 P.7->A.3 P.8->A.3

We can roll up mass properties to non-leaf elements as follows:

rollup_mass_props(test_tree, test_table)
#>     id parent mass Cx Cy Cz Ixx  Ixy   Ixz Iyy   Iyz Izz POIconv Ipoint
#> 1  A.1          21  0  0  0 144 -4.8 -24.8 144 -23.2 139       -  FALSE
#> 2  A.2    A.1    8  1  0  0  32 -0.4  -0.4  24   0.4  24       -  FALSE
#> 3  A.3    A.1    8 -1  0  0  32 -0.4  -0.4  24   0.4  24       -  FALSE
#> 4  C.1    A.1    5  0  0  0  80 -4.0 -24.0  80 -24.0  75       -  FALSE
#> 5  P.1    A.2    2  1  1  1   4 -0.1  -0.1   4   0.1   4       -  FALSE
#> 6  P.2    A.2    2  1  1 -1   4 -0.1  -0.1   4   0.1   4       -  FALSE
#> 7  P.3    A.2    2  1 -1  1   4 -0.1  -0.1   4   0.1   4       -  FALSE
#> 8  P.4    A.2    2  1 -1 -1   4 -0.1  -0.1   4   0.1   4       -  FALSE
#> 9  P.5    A.3    2 -1  1  1   4 -0.1  -0.1   4   0.1   4       -  FALSE
#> 10 P.6    A.3    2 -1  1 -1   4 -0.1  -0.1   4   0.1   4       -  FALSE
#> 11 P.7    A.3    2 -1 -1  1   4 -0.1  -0.1   4   0.1   4       -  FALSE
#> 12 P.8    A.3    2 -1 -1 -1   4 -0.1  -0.1   4   0.1   4       -  FALSE

References

Zimmerman, Robert L., and John H. Nakai. 2005. “Are You Sure? Uncertainty in Mass Properties Engineering.” In 64th Annual International Conference on Mass Properties Engineering, 123–60. Society of Allied Weight Engineers.