Templates
Using conceptual templates, Adams/Car allows you to study system-level vehicle dynamics without having to create detailed multibody suspension models.
Figure 1 Conceptual Steering System
The conceptual steering system is a very simple model of steering that communicates the steering-wheel revolute joint to the conceptual suspension system. The conceptual suspension system uses the rotation of the joint i and j markers as a measure of the steering input.
The conceptual steering system template consists of a steering wheel and column rotating through a revolute joint. The revolute joint connects the rigid bodies to a mount part.
Mount parts provide the connectivity from the template to the body subsystems. Output communicators publish steering limits for displacement, angle, and force, and torque information.
Using conceptual templates, Adams/Car allows you to study system-level vehicle dynamics without having to create detailed multibody suspension models. You can use the conceptual suspension system to define the wheel movements with respect to the body using a collection of characteristic curves or dependencies.
Figure 2 Conceptual Suspension System
Suspension or full-vehicle analyses. You can mix and match conceptual suspensions in a full-vehicle assembly with multibody suspension models.
References the file dwb_front.scf, stored in the suspension_curves.tbl directory in the Adams/Car shared database. The suspension characteristic file defines kinematic relations or dependencies between suspension characteristic angles, suspension track, and base and the vertical wheel and steer travel.
Three curve-to-curve constraints drive each wheel carrier along a predefined trajectory. A user-written curve subroutine calculates the trajectory depending on the inputs to the system, such as the forces and torques coming from the tire subsystem and the amount of wheel and steer travel.
A conceptual suspension will have four degrees of freedom. A conceptual vehicle, therefore, will have 14 degrees of freedom. The following table lists the model topology for the left side of the template. The right side entities are connected in a similar way.
The toe and camber parameter values define the wheel spin axis, and the unsprung mass parameter variable defines the wheel carrier part mass. Finally, 68 hidden variables define the dependency flags array, with each of parameters setting the status (active or inactive) of a dependency.
Mount parts provide connectivity from the template to the body subsystems and differential. Input communicators receive information about the tire forces, the steer axis, and the steering-wheel joint. Output communicators publish toe, camber, steer axis, and wheel center location information.
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Spring and damper entities in the conceptual suspension template consist of a special user-defined element. A user-written subroutine computes the forces. The subroutine takes into account the nonlinear spring/damper characteristics and the stabilizer bar forces
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Figure 3 Disc-Brake System
Full-vehicle analysis to simulate the effect of braking on the dynamics of the vehicle.
The disc-brake system template represents a simple model of a brake system. It applies a rotational torque between the caliper and the rotor.
The caliper part is mounted to the suspension upright, while the rotor is mounted to the wheel. A rotational SFORCE is applied between the two parts.
The toe and camber values that the suspension subsystem publishes define the spin axis orientation. In addition, the braking torque is expressed as a function of a number of parameters.
The disc-brake template is a simple model of a brake system. It does not model the complex interaction between the rotor and caliper.
Mount parts provide the connectivity between the template and suspension subsystems. Input communicators receive information about the toe and camber suspension orientation and the wheel-center location. Input to the brake system is brake demand.
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A double-wishbone suspension is one of the most common suspension designs. It uses two lateral control arms to hold the wheel carrier and control its movements.
Figure 4 Double-Wishbone Suspension
The double-wishbone template represents the most common design for doublewishbone suspensions. You can use the template as a front steerable suspension or as a rear non-steerable suspension.
You can set subsystems based on this template to kinematic or compliant mode. In kinematic mode, Adams/Car replaces the bushings that connect the control arms to the body mount part with a corresponding purely kinematic constraint. Adams/Car also does this for the top mount and lower strut mount.
You can deactivate the subframe part, as well as the halfshafts. A spring acts between the upper mount part and the lower strut. A bumpstop acts between the upper and lower strut parts.
The lower wishbone connects to a subframe or to the mount if you've deactivated the subframe. The upper wishbone connects to the body mount part. A spherical joint constrains the upright part to the upper and lower arms.
A spherical joint also connects the tie rods to the uprights. Tie rods attach to mount parts through convel joints. Convel joints also connect the tripots to the drive shafts. A static rotation control actuator locks the rotational degree of freedom of the hub during quasi-static analyses.