The SVC Iterate event helps analysts achieve specific vehicle targets with their MD Adams model. For the full-vehicle version, any combination of the following targets can be selected:

This event will modify the vehicle's sprung mass and spring information as necessary to attempt to achieve desired values for the listed targets. It will accomplish this by iteratively running the Static Vehicle Characteristics (SVC) Event.

The first property group within SVC Iterate involves mass and inertia properties. Data in the .btt file will be varied to try and achieve targets for Corner Loads, Overall Vehicle CG Height, and Overall Vehicle Inertia.

Three mass options are available: body, cargo, and J-turn cargo. For the body option, the sprung mass part is varied to try and match the desired vehicle properties. For the cargo option, a new cargo part is added and adjusted to match the properties. The J-turn cargo option adds a specific loading box type used in truck testing. This loading box has a fixed density of 2745 kg/m3 and a height of 8 in. For this option additional input parameters are required: loading width, loading floor height, front X loading limit, and rear X loading limit.

J-Turn Cargo Placement Process

For both cargo options, a cargo part is added to the model. Any other cargo parts that were originally included in the model will remain in the model. Part numbers 528 and 529 are assigned to the cargo and J-turn cargo parts, respectively. If your model has parts with these ID's, please renumber them.

Adams/Chassis will attempt to match 8 outputs (4 tire forces + CG height + 3 inertias) while varying 7 parameters (CG XYZ, mass, and 3 inertias). CG Height and Vehicle Inertia targets will almost always be achieved, but sometimes not all 4 tire forces can be achieved. 3 parameters (CG X, CG Y, and mass) will be varied to try and match the 4 loads, and sometimes it is impossible to match them exactly. SVC-Iterate will get as close as possible, and it should match your desired overall front-rear and left-right force balances.

Front and Rear Ride HeightThe ride height adjustment option is available for coil and torsion spring suspensions. Leaf spring suspensions are not supported. Data in the .fst and .rst files is varied for this option. For coil spring suspensions, the spring free length is varied. For torsion bar suspensions, the torsion bar preload angle is varied.

Front and Rear Wheel RateThe ride height adjustment option is also available for coil and torsion spring suspensions. For coil spring suspensions, the spring rate is varied. For torsion bar suspensions, the torsion bar diameter is varied.

After all tolerances are met new datafiles are created with the new mass and spring information. The new datafiles are named by adding a .new to your original filename. The desired targets and achieved values are written to the header section of each new datafile.