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Optimizing the dynamic performance of automotive components and subsystems
 Reducing development time and costs, while still delivering high quality products, is one of the major challenges for automotive OEMs and their suppliers in today’s competitive market landscape. To meet these challenges, the focus is on product innovation, process efficiency and product and process versatility. It is clear that the simulation of the products’ key performance attributes plays a crucial role in the overall development process.
Especially automotive suppliers are in a very tight development and bidding process with the OEM. They have to be able to deliver proposals based on specification from the OEM, prove their technical capability to deliver the required specifications at the lowest price and differentiate themselves from the competition by finding innovative solutions towards specific problems, often requiring fast an in-depth engineering. These include many vehicle components and subsystems with complex mechanisms and moving parts ranging from braking and steering systems, gears and gear shift mechanisms, door systems, seat mechanisms, convertible roofs, locks and latches to storage compartments switches and others – some of which are crucial to the brand value of the OEM. To win the innovation race, automotive suppliers are front-loading their design process by investing into virtual prototyping tools which will allow them to simulate the functional performance of their subsystems to ensure smooth, continuous and quite motion of all moving parts and meet the ever more demanding comfort requirements of automotive customers.
Based on a selected number of application examples, this paper illustrates how LMS Virtual.Lab Motion models any kind of mechanical or mechatronic system and allows you to predict its real-life behavior early in the design phase.
Engineering the dynamic performance of an electric motor
Every vehicle contains numerous electric motors to drive moving parts like wipers, window lifts, power doors, roof systems, power seats, external mirrors, for pumping fluids in engine cooling or air-conditionings and for many other applications like ABS brakes, starters, door locks, alternators, etc. The main requirements to those products are a low price, minimal noise, high power density and reliability.
Simulating the behavior of an electric motor includes a number of challenges, such as the simulation of the friction contact between brushes and commutator, the static/dynamic unbalance, the electro-magnetics, the bearing forces and more.
LMS Virtual.Lab Motion provides features to accurately model each of these static and dynamic effects.  Additionally, the calculated loads and accelerations of the system are immediately useful for further analyses such as Acoustics, Noise & Vibration or Durability within the same LMS Virtual.Lab environment.
Virtual.Lab Motion allows the user to easily build detailed models of the complete engine assembly at any level of fidelity required to detect the root cause of a phenomena or to optimize the design for a characteristic performance attribute by bringing the complete CAD geometry into VL Motion or even working with a fully CAD-associative model in the CATIA V5 environment. Most robust and efficient multi-body dynamic solvers perform real-life simulations like a complete speed sweep of the engine run-up in minimal time, calculating bearing loads, critical rpm, brush forces, housing vibrations and other results which can then be studied in a variety of 2d displays as well as 3d animations.
The unique multi-physics functionality of LMS Virtual. Lab eliminates all interfacing problems when using the loads from the engine run-up calculated in the Motion workbench for subsequent predictions of the noise radiation in the Acoustics workbench or the fatigue life prediction in the Durability workbench.
Optimizing a power sliding door system For closure applications, such as automatic windows, roof systems, power back doors and power sliding doors, the challenges range from operating the system as smoothly and quietly as possible while fulfilling the ergonometric requirements, predicting the operational forces and torques for layout of the drive units to minimizing the weight while maximizing the components static strength and dynamic stiffness.  To not compromise on any of these partially conflicting targets, designers of power door systems are confronted with some tough engineering challenges. Clutch mechanisms are required for switching between manual and power door operation, actuators for fully closing the door from half latched position as well as sensors and switches for tracing all positions and operating speeds and checking the lock engagement. All actuators must be operable regardless of the position of the door. For safety reasons touch sensors are required to avoid injury of persons interfering with the door during its operation movement. For comfort reasons the drive unit needs to be designed and positioned to provide sufficient space for passengers entrance and exit and not be an obstacle for rear viewing. Finally, the light-weight components must be designed not only for fatigue life under all operating forces but also for reliability under certain conditions of miss-use (e.g., manual release of the sliding door while the car is parked on a steep incline).
A multi-body dynamic analysis model is developed for the evaluation of loads and necessary drive forces. The actuators and controls are added to the multibody system, manually or with the available controls & hydraulics library, and the systems is solved trough co-simulation with Imagine.Lab or other software such as Matlab/Simulink, Easy 5, DSH+, etc. Simulated results are easily compared with experimental ones in order to validate the model.
 Important in the simulation of those closure systems are the contact forces available in Virtual.Lab Motion. The CAD contact allows to model contact between parts of any geometry. Friction modeling also allows to model tangential forces between parts, which is not possible with pure kinematic analysis. Virtual.Lab Motion furthermore enables to quickly monitor the effects of any changes in the analysis and to drive optimization on parameters by the use of design tables and the integrated optimization algorithms. This is done by imposing a desired target for an output function which varies with the value of the selected parameters to be optimized. It enables the systematic design improvement to meet target specifications or e.g. to fit a simulated contact force curve on a curve obtained by physical test.
Designers of power door systems select LMS Virtual.Lab Motion for its unique capabilities and specific sliding door modeling features compared to generic MBS tools. These include full associativity with the CATIA V5 CAD data, a graphical user interface fully customized to streamline and automate this specific simulation process, dedicated cable modeling tools and highly efficient roller-rail-cable contact algorithms as well as the seamless integration to industry standard controls simulation packages.
Troubleshooting unwanted behavior in a glove compartment
The dashboard glove compartment in this example encountered a problem while driving over cobble stones at
a certain speed: it actually opened by itself, obviously an unacceptable behavior.  The opening mechanism of the glove compartment needs to be designed to easily and smoothly operate as expected from an upper class car customer and equally stay firmly closed under severe dynamics loads across all frequency ranges while the car is driven on rough roads or even off-road. At the same time the pressure on costs prohibit complex locking mechanisms involving expensive parts. To tackle these challenges, LMS Virtual.Lab Motion helps engineers optimize the shape of the latches and contact surfaces required to firmly hold the compartment closed as well as tune the springs and damping elements to ensure a smooth operation when opening the compartment with minimal force applied by the driver or passenger.
Using LMS Virtual.Lab Motion it is possible to simulate the isolated glove compartment submitted to various loads conditions in order to emphasize a resonance response mode of the system at a certain frequency. This accurate simulation was then used to solve the problem by changing the design of the locking mechanism of the
system.
Applying an excitation to the attachment points of the compartment and then running a frequency sweep with LMS Virtual.Lab Motion, i.e. submitting the compartment to a virtual shaker test, allows the design engineer to
closely observe the dynamic behavior of each part under the full scope of real-life operating conditions and immediately detect any issues the locking mechanism may have due to resonance effects of the latches at critical frequencies.  This example shows how the accurate modeling of contact and friction forces play a key role in the simulation and how the simulation sometimes outperforms the test for specific topics. Virtual product creation processes allow the engineers getting their design of complex mechanisms right before the first prototype is molded.
And the motion simulation will not only give users insight into problem areas or help understand the root causes of malfunction, additionally the photorealistic animation of the dynamic lid motion is an impressive instrument to validate the design against the customer’s quality expectations up-front in the design process.
Simulate your product’s real-world performance with LMS Virtual.Lab Motion
LMS Virtual.Lab Motion is a complete and integrated solution to simulate realistic motion and loads of mechanical systems. It permits engineers to quickly analyze and optimize the real-world behavior of the mechanical design, before committing to expensive physical prototype testing.  LMS Virtual.Lab Motion provides leading edge technology in solid modeling, parameterization, CAD Geometry, flexible body features, control and hydraulic capabilities, solver performance, animation, and post-processing capabilities. It integrates all required functionalities into a single and user-friendly desktop environment, eliminating the need for multiple solutions and time consuming data transfers. Virtual.Lab’s embedment in CATIA V5 provides quick and easy updating of results after change in design. It is a multi-attribute solution with seamless integration of Durability, Noise & Vibration, Acoustics and Optimization. It’s also a flexible solution due to the numerous compatible imported CAD files formats and exported result files formats. External FE solvers also are available while staying in the Virtual.Lab environment with automatic data flow between Virtual.Lab and the solver.
Dedicated animation, graphing and post-processing features help engineers to easily identify and effectively solve the root causes of an engineering problem. Users can review dynamic responses, including all system loads, accelerations, velocities, and positions. Simulation results visualized on different types of displays, allow colleagues and customers to "step into" the design and to make critical engineering decisions.
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