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Modelling and analysis of suspension systems 235<br />

Table 4.14<br />

Force<br />

Comparison of force vectors computed by theory and MSC.ADAMS<br />

Force vectors<br />

Theory<br />

MSC.ADAMS<br />

F x (N) F y (N) F z (N) F x (N) F y (N) F z (N)<br />

F A31 645.173 2006.948 3412.360 645.173 2006.950 3412.360<br />

F B31 204.112 3022.800 3353.266 204.112 3022.800 3353.270<br />

F C37 116.421 349.263 16 919.843 116.421 349.263 16 919.800<br />

F D34 557.482 4680.486 10 154.217 557.482 4680.490 10 154.200<br />

F E21 557.482 1453.911 47.583 557.482 1453.910 47.582<br />

F F21 0.0 2787.021 91.212 0.0 2787.020 91.212<br />

F G24 557.482 4240.932 138.979 557.482 4240.930 138.794<br />

F H54 0.0 439.554 15.942 0.0 439.554 15.423<br />

Z 1<br />

X 1 Y 1<br />

O 1<br />

m 2 {A G 2 } 1 Plane of<br />

{F F 21 } 1<br />

geometric<br />

F<br />

Y symmetry<br />

2<br />

{F E21 } 1 E<br />

•<br />

•<br />

{ω 2 } 1/2<br />

Body 2<br />

Z 2<br />

O 2 G 2 X<br />

•<br />

{α 2<br />

2 } 1/2<br />

G<br />

m 2 {g} 1<br />

Fig. 4.76 Free-body diagram for suspension lower wishbone Body 2<br />

{F G 24 } 1<br />

20 unknown constraint forces as used in the previous static analysis.<br />

Referring back to Chapter 2, however, the reader will realize that the addition<br />

of inertial forces and the use of a local body centred co-ordinate system<br />

for the moment balance will add to the complexity of the solution. For<br />

brevity a full theoretical solution will not be performed here but rather the<br />

six equations of motion for Body 2 will be set up using, by way of example,<br />

the velocities and accelerations found earlier. The process of setting up<br />

the equations of motion for the other bodies would follow in a similar manner.<br />

Body 2 can be considered in isolation as illustrated with the free-body<br />

diagram shown in Figure 4.76.<br />

For the dynamic analysis we can take it that the physical properties of the<br />

suspension component, mass, mass moments of inertia, centre of mass<br />

location and orientation of the body principal axis system, are all known.<br />

The co-ordinate data provided with this example has only provided definitions<br />

so far for the locations of points such as those defining suspension

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