Realistic System and Component Loads Prediction

With LMS Virtual.Lab, system loads can be generated through dynamic simulation, even before they can be measured on a physical prototype. Virtual driver sessions and road tests performed on a previously released vehicle form the basis of two distinctive simulation approaches.

Digital test track

During realistically simulated driver sessions, a virtual vehicle equipped with virtual tires, drives around over digital test tracks. Its tire models are capable of calculating the dynamic forces and moments acting on the spindles of the vehicle. LMS CDTire (Comfort – Durability) is a tire model that consists of physical entities such as masses, springs, dampers and sensor points. To keep processing times acceptable, the virtual tire is subdivided on macroscopic level, rather than with finite elements.

LMS CDTire supports:

2D tire models with stiff ring (CDT20) or flexible ring (CDT30)
Complex full 3D tire model (CDT40) with a multiple flexible ring, suitable for any type of road surface.

Hybrid road

An alternative solution, pioneered by LMS, draws on a hybrid approach, which combines test-based loads with virtual simulations. It applies a new transformation methodology to accurately determine system loads, before they can be gained through measurement. It starts from wheel spindle loads measured on a previous model vehicle and converts these into wheel spindle displacements. The breakthrough of this approach is that these displacements are much less vehicle-dependent, since they are based on road surfaces, rather than on vehicle characteristics.

Accurately gaining dynamic component forces

The LMS Virtual.Lab Motion solver evolved from LMS DADS, which is widely renowned for its accuracy and inherent robustness and stability. It offers a vast choice of high-performance time-domain solvers for kinematic, transient dynamic, quasi-static and pre-load analysis. LMS Virtual.Lab Motion is capable of predicting true dynamic stresses and deformations by accurately taking mass effects and vibrations into account. Automatically generated Craig-Bampton cases enable FE analyses to be automatically driven. Top-speed is achieved by state-of-the-art reduction techniques. Modal participation factors are automatically made available to the downstream fatigue- life prediction analysis.

Delivering loads for early durability testing

Component loads retrieved from LMS Virtual.Lab Motion are not only used as input for virtual fatigue-life predictions, they are also very useful for driving physical durability tests. Realistic component loading and pre-information on critical locations signifi cantly improves the accuracy and effi ciency of component durability tests.