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Doubt regarding compliance matrix calculation error in suspension analysis

I have read online help regarding this matter and understand that whenever we perform a standard event (for eg Suspension Analysis-----> Steering, which I am trying on one of the projects), the compliance matrix is calculated for every Joint and then various elements of this matrix are used for calculating different requests such as Ride rate, ride steer and a number of other parameters. The model which I have built has a number of idealized constraints (Convel, spherical, revoulte, fixed joints in the steering template). I have tried to replace as many fixed joints in the suspension templates as possible with bushes to see if it worked, but the problem still persists. There are also no redundant constraints in the model. I have also double checked the communicators that I have used and ensured that none of the parts are inadvertently connected to the ground. without the matrix, none of the requests which use this matrix are being calculated. The model I am trying to simulate is that of a tandem axle front suspension with bell-crank equalizing links and twin steering. I have also taken a look at the same assembly from the shared truck database. There seem to be quite a lot of idealized constraints in that model, but still there seems to be no issue when I simulate a similar steering event using that model. Can anybody suggest any corrections I may be able to incorporate into my model to make it work?
Parents
  • Hi Alexis, thanks for your prompt reply, here is the error I am getting. Yes, I have compared how the ATruck database model communicates with the rig and I have included all the communicators. As you can see in the following list of errors and warnings, once the matrix calculation fails, all the other calculations are failing. However, it continues to perform the simulation till the last step and I can also see the animation. Thanks for your time!
     
     
    ****** Performing Quasi-Static Simulation ******
     
    acar/acm_cmat
    **** Error:
     
    Compliance matrix calculation failed.
     
    acar/acm_rmvdof
    *** Warning:
    Singular submatrix - unable to remove DOF's
    One of the DOF's may already have zero
    compliance.
     
    acar/ac_sdm_prop
    *** Warning:
    Failure to remove the steering travel dof from the suspension compliance mat
    ISTAT = 1
     
    acar/FVSA
    *** Warning:
    The left vertical deflection compliance terms are equal to zero.
    Therefore, the front view swing arm angle will equal zero.
     
    acar/FVSA
    *** Warning:
    The right vertical deflection compliance terms are equal to zero.
    Therefore, the front view swing arm angle will equal zero.
     
    acar/asfvsl
    *** Warning:
    The left side rotation is equal to zero.
    Therefore, the front view swing arm length will equal zero.
     
    acar/asfvsl
    *** Warning:
    The right side rotation is equal to zero.
    Therefore, the front view swing arm length will equal zero.
     
    acar/assvsa
    *** Warning:
    The left vertical deflection compliance terms are equal to zero.
    Therefore, the side view swing arm angle will equal zero.
     
    acar/assvsa
    *** Warning:
    The right vertical deflection compliance terms are equal to zero.
    Therefore, the side view swing arm angle will equal zero.
     
    acar/svsl
    *** Warning:
    the left side rotation is equal to zero.
    therefore, the side view swing arm length will equal zero.
     
    acar/svsl
    *** Warning:
    the right side rotation is equal to zero.
    therefore, the side view swing arm length will equal zero.
     
    acar/RIDE
    **** Error:
     
    The left vertical deflection compliance terms are equal to zero.
    Therefore, the suspension ride rate will equal zero.
     
    acar/RIDE
    **** Error:
     
    The right vertical deflection compliance terms are equal to zero.
    Therefore, the suspension ride rate will equal zero.
     
    acar/ROLL
    **** Error:
     
    The vertical deflection compliance terms are equal to zero.
    Therefore, the suspension roll rate will equal zero.
     
    acar/acc_rid_ste
    **** Error:
     
    The left wheel ride stiffness is too large
    to compute the ride steer. The ride steer
    is undefined.
     
    acar/acc_rid_ste
    **** Error:
     
    The right wheel ride stiffness is too large
    to compute the ride steer. The ride steer
    is undefined.
     
    acar/acc_rol_cen
    **** Error:
     
    Unable to calculate the roll center because:
    the left contact patch is constrained.
    the right contact patch is constrained.
     
    acar/FVSA
    *** Warning:
    The left vertical deflection compliance terms are equal to zero.
    Therefore, the front view swing arm angle will equal zero.
     
    acar/FVSA
    *** Warning:
    The right vertical deflection compliance terms are equal to zero.
    Therefore, the front view swing arm angle will equal zero.
     
    acar/asfvsl
    *** Warning:
    The left side rotation is equal to zero.
    Therefore, the front view swing arm length will equal zero.
     
    acar/asfvsl
    *** Warning:
    The right side rotation is equal to zero.
    Therefore, the front view swing arm length will equal zero.
     
    acar/assvsa
    *** Warning:
    The left vertical deflection compliance terms are equal to zero.
    Therefore, the side view swing arm angle will equal zero.
     
    acar/assvsa
    *** Warning:
    The right vertical deflection compliance terms are equal to zero.
    Therefore, the side view swing arm angle will equal zero.
     
    acar/svsl
    *** Warning:
    the left side rotation is equal to zero.
    therefore, the side view swing arm length will equal zero.
     
    acar/svsl
    *** Warning:
    the right side rotation is equal to zero.
    therefore, the side view swing arm length will equal zero.
     
    acar/RIDE
    **** Error:
     
    The left vertical deflection compliance terms are equal to zero.
    Therefore, the suspension ride rate will equal zero.
     
    acar/RIDE
    **** Error:
     
    The right vertical deflection compliance terms are equal to zero.
    Therefore, the suspension ride rate will equal zero.
     
    acar/ROLL
    **** Error:
     
    The vertical deflection compliance terms are equal to zero.
    Therefore, the suspension roll rate will equal zero.
     
    acar/acc_rid_ste
    **** Error:
     
    The left wheel ride stiffness is too large
    to compute the ride steer. The ride steer
    is undefined.
     
    acar/acc_rid_ste
    **** Error:
     
    The right wheel ride stiffness is too large
    to compute the ride steer. The ride steer
    is undefined.
     
    acar/acc_rol_cen
    **** Error:
     
    Unable to calculate the roll center because:
    the left contact patch is constrained.
    the right contact patch is constrained.               
Reply
  • Hi Alexis, thanks for your prompt reply, here is the error I am getting. Yes, I have compared how the ATruck database model communicates with the rig and I have included all the communicators. As you can see in the following list of errors and warnings, once the matrix calculation fails, all the other calculations are failing. However, it continues to perform the simulation till the last step and I can also see the animation. Thanks for your time!
     
     
    ****** Performing Quasi-Static Simulation ******
     
    acar/acm_cmat
    **** Error:
     
    Compliance matrix calculation failed.
     
    acar/acm_rmvdof
    *** Warning:
    Singular submatrix - unable to remove DOF's
    One of the DOF's may already have zero
    compliance.
     
    acar/ac_sdm_prop
    *** Warning:
    Failure to remove the steering travel dof from the suspension compliance mat
    ISTAT = 1
     
    acar/FVSA
    *** Warning:
    The left vertical deflection compliance terms are equal to zero.
    Therefore, the front view swing arm angle will equal zero.
     
    acar/FVSA
    *** Warning:
    The right vertical deflection compliance terms are equal to zero.
    Therefore, the front view swing arm angle will equal zero.
     
    acar/asfvsl
    *** Warning:
    The left side rotation is equal to zero.
    Therefore, the front view swing arm length will equal zero.
     
    acar/asfvsl
    *** Warning:
    The right side rotation is equal to zero.
    Therefore, the front view swing arm length will equal zero.
     
    acar/assvsa
    *** Warning:
    The left vertical deflection compliance terms are equal to zero.
    Therefore, the side view swing arm angle will equal zero.
     
    acar/assvsa
    *** Warning:
    The right vertical deflection compliance terms are equal to zero.
    Therefore, the side view swing arm angle will equal zero.
     
    acar/svsl
    *** Warning:
    the left side rotation is equal to zero.
    therefore, the side view swing arm length will equal zero.
     
    acar/svsl
    *** Warning:
    the right side rotation is equal to zero.
    therefore, the side view swing arm length will equal zero.
     
    acar/RIDE
    **** Error:
     
    The left vertical deflection compliance terms are equal to zero.
    Therefore, the suspension ride rate will equal zero.
     
    acar/RIDE
    **** Error:
     
    The right vertical deflection compliance terms are equal to zero.
    Therefore, the suspension ride rate will equal zero.
     
    acar/ROLL
    **** Error:
     
    The vertical deflection compliance terms are equal to zero.
    Therefore, the suspension roll rate will equal zero.
     
    acar/acc_rid_ste
    **** Error:
     
    The left wheel ride stiffness is too large
    to compute the ride steer. The ride steer
    is undefined.
     
    acar/acc_rid_ste
    **** Error:
     
    The right wheel ride stiffness is too large
    to compute the ride steer. The ride steer
    is undefined.
     
    acar/acc_rol_cen
    **** Error:
     
    Unable to calculate the roll center because:
    the left contact patch is constrained.
    the right contact patch is constrained.
     
    acar/FVSA
    *** Warning:
    The left vertical deflection compliance terms are equal to zero.
    Therefore, the front view swing arm angle will equal zero.
     
    acar/FVSA
    *** Warning:
    The right vertical deflection compliance terms are equal to zero.
    Therefore, the front view swing arm angle will equal zero.
     
    acar/asfvsl
    *** Warning:
    The left side rotation is equal to zero.
    Therefore, the front view swing arm length will equal zero.
     
    acar/asfvsl
    *** Warning:
    The right side rotation is equal to zero.
    Therefore, the front view swing arm length will equal zero.
     
    acar/assvsa
    *** Warning:
    The left vertical deflection compliance terms are equal to zero.
    Therefore, the side view swing arm angle will equal zero.
     
    acar/assvsa
    *** Warning:
    The right vertical deflection compliance terms are equal to zero.
    Therefore, the side view swing arm angle will equal zero.
     
    acar/svsl
    *** Warning:
    the left side rotation is equal to zero.
    therefore, the side view swing arm length will equal zero.
     
    acar/svsl
    *** Warning:
    the right side rotation is equal to zero.
    therefore, the side view swing arm length will equal zero.
     
    acar/RIDE
    **** Error:
     
    The left vertical deflection compliance terms are equal to zero.
    Therefore, the suspension ride rate will equal zero.
     
    acar/RIDE
    **** Error:
     
    The right vertical deflection compliance terms are equal to zero.
    Therefore, the suspension ride rate will equal zero.
     
    acar/ROLL
    **** Error:
     
    The vertical deflection compliance terms are equal to zero.
    Therefore, the suspension roll rate will equal zero.
     
    acar/acc_rid_ste
    **** Error:
     
    The left wheel ride stiffness is too large
    to compute the ride steer. The ride steer
    is undefined.
     
    acar/acc_rid_ste
    **** Error:
     
    The right wheel ride stiffness is too large
    to compute the ride steer. The ride steer
    is undefined.
     
    acar/acc_rol_cen
    **** Error:
     
    Unable to calculate the roll center because:
    the left contact patch is constrained.
    the right contact patch is constrained.               
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