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--- accounting_for_inertia [2018/06/13 13:53]
marijn.nijenhuis
+++ accounting_for_inertia [2018/06/13 16:49]
marijn.nijenhuis [Adding mass and inertia properties to Spacar]
@@ Line 38: / Line 38: @@
 ===== Adding mass and inertia properties to Spacar =====
-For this example a single leafsprings is simulated between node 1 ([0,0,0]) and node 2 ([0 0.1 0]), with one end of the wrench attached to node 2 (which coincides with the position of the coordinate system in SolidWorks). Furthermore, a third node at the center of mass of the wrench ([0.055 0.1 0.003]) is rigidly connected to node 2. At this node in the center of mass of the wrench, both the mass and moment of mass properties are added with the ''nprops(i).mass'' and ''nprops(i).mominertia'' fields.
+For this example a single leafsprings is simulated between node 1 ([0,0,0]) and node 2 ([0 0.1 0]), with one end of the wrench attached to node 2 (which coincides with the position of the coordinate system in SolidWorks). Furthermore, a third node at the center of mass of the wrench ([0.055 0.1 0.003]) is connected to node 2 with a rigid massless element. At the node in the center of mass of the wrench, both the mass and moment of mass properties are added with the ''nprops(i).mass'' and ''nprops(i).mominertia'' fields.
-** Check the full syntax list for the correct use of ''nprops(i).mominertia'' because the definition differs from the numbers that SolidWorks returns **. SolidWorks returns
+** Check the full syntax list for the correct use of ''nprops(i).mominertia'' because the definition differs from the numbers that SolidWorks returns **. The Mass Properties window in SolidWorks returns
-$$ \begin{bmatrix} I_xx & -I_xy & -I_xz \\ -I_xy & I_yy & -I_yz \\ -I_yz & -I_xz & I_zz \end{bmatrix} $$
+$$ \begin{bmatrix} I_{xx} & -I_{xy} & -I_{xz} \\ -I_{xy} & I_{yy} & -I_{yz} \\ -I_{xz} & -I_{yz} & I_{zz} \end{bmatrix} $$
 ''nprops(i).mominertia'' consists of a vector with length six, [Ixx Ixy Ixz Iyy Iyz Izz] in kgm<sup>2</sup>. Note the tensor components are needed, so Ixy, Ixz and Iyz represent the negative of the products of inertia (which are provided by SolidWorks).

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