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EuroBrake 2022: Brake testing & development: future trends and perspectives session overview

The Brake testing & development: future trends and perspectives session will take place on Wednesday May 18th and will be chaired by Fabio Squadrani of Applus IDIADA and co-chaired by Deaglan O’Meachair, Brakebetter.

Topics and speakers for the session include:

Brake NVH development process improvement through machine learning

Antonio Rubio, Applus IDIADA

Braking systems development is currently facing some huge challenges. The first one is electrification. The presence of regenerative braking and the standard adoption of electro-hydraulic braking systems is completely changing the way braking systems are developed and validated.

The second one is connectivity. This concept is not only applying to the vehicle itself, but also to the development process. Currently vehicles are tested in multiple locations on a worldwide basis. Witnessing testing is becoming every day more expensive and complicated, particularly for vehicles which are sold in different markets.

The third big challenge is certainly the increasing level of driving automation. The pure concept of vehicle assessment and sign-off is shifted from the driver perspective to the “occupant” perspective. Comfort cannot be jeopardized, a good balance between performance and refinement must be guaranteed.

To respond to these three big challenges to brake development, the authors are presenting how artificial intelligence can support the identification of brake noise in real time. In this paper a summary of the machine learning techniques used to identify brake noise events are presented.

Particularly, the validation of the algorithm is presented in order to cover not only brake squeal in standard condition, but also to detect different brake noises, under different testing conditions (different standards, city and mountain driving, low and high ambient temperature, different vehicle category).

Finally, the authors are presenting an automatic process which is managing the complete process, from driving and rating, through detection, brake noise automated analysis and finally the upload of the testing report and relevant information in a connected secure environment.

Dynamic wheel loads application on dyno bench and their effects on brake system test

Claudio Benini, Brembo S.p.A

Pushed by the new technologies that are hitting the automotive market, OEMs and Suppliers are increasingly dealing with the need to enhance product lifetime efficiency reducing development times and costs. Consequently, simulation is gaining more and more relevance and extensive vehicle testing campaign are leaving room to focused and optimized laboratory and dyno tests.

In this scenario the ability to faithfully reproduce vehicle behaviour in a wide range of conditions is a key factor for systems development. Speaking about dyno testing a lot of significant improvements have already been achieved either in matter of procedures and controls. A step forward is represented by the expansion to include also lateral and longitudinal dynamics, integrating standard dyno operations with vehicle wheel dynamic loads application: as well-known their influence may not be negligible when disc deformation or pad position play a relevant role for certain NVH issues.

A fully integrated dynamic system with actuators for longitudinal and lateral loads has been developed and installed on a Brembo dynamic bench in the frame of a cooperation with Link Engineering.

Such device, targeted to be light and flexible in its setup and tuning, confirmed itself to be representative of vehicle actual behaviour and reliable for deeper investigations of NVH phenomena, as shown in some preliminary validation results.

Development of novel brake pad material concepts for future (electric) assembly matrices

Niels Wächter, Volkswagen AG

The brake pad is a crucial part of the brake and together with its friction couple, mostly, dictates the brake’s characteristics. Nowadays, brakes shall be, among other requirements, performant, simultaneously NVH-optimized, durable, inexpensive and environmentally friendly. The task of the friction couple is to unify these partly contradicting requirements. But the friction material often is considered as a black-box as it is a multi-substance mixture with dozens of raw materials.

Interactions between those ingredients and their effect on the required properties are not fully understood. It is expected that there will be a shift in brake (pad) requirements for future vehicle concepts. Electrification, autonomous driving, digitalization, and environmental requirements bring new brake (pad) requirements already today. Friction stability, corrosion and particle emissions are just a few of the new emerging demands. How can requirements specifically for future mobility be covered by suitable brake pad material concepts?

In this study, first, a comprehensive overview of future mobility is presented, and future requirements are derived with a top-down approach. Coming from general vehicle requirements of future mobility concepts, friction couple requirements are deducted, and a set of targeted prioritized properties is discussed. In cooperation with suppliers, raw material classes are categorized regarding which properties they cause in the brake pad. Additionally, test specifications are re-designed towards the found new mobility scenarios. The desired prioritized target properties are then tested prototypically for their fulfilment.

Combining inertia dynamometers with vehicle dynamics model to perform closed-loop testing below wheel slip conditions on ICE and EVs

Carlos Agudelo, Link Engineering Co.

Inertia dynamometer testing needs to evolve. They need to allow the test engineer to embed the test in a vehicle environment: Developing or adaptation of the braking system as a mechatronics/software integration. Having access to advanced real-time control systems to simulate vehicle modules and vehicle dynamics. And a relentless pace to assess more conditions, scenarios, and manoeuvres, way before going to the proving ground (if at all). Since dynamic torque output (as a direct effect of changes in the coefficient of friction) changes during and between braking events, having the actual brake in the control loop avoids the requirement (and risks) of attempting to model all the complexities and nuances of the brake corner. After presenting the key elements and architecture of the test environment, this paper uses examples with full-scale inertia dynamometer testing with selected manoeuvres of the SAE J2707 block wear cycle. The test cases and examples include several matrices to a) compare the Vehicle Dynamics Model control to the native dynamometer control system, b) assess the effects on torque output when changing the vehicle mass and weight distribution, c) determine the sensitivity and responsiveness of the intelligent test bench to changes in brake balance, d) and assess the response to changes in certain parameters (battery power, regenerative torque, and state of charge) of the electric machine within the intelligent test bench. By quantifying and visualizing the dynamic interactions between the vehicle dynamics simulation and the inertia dynamometer, the test engineer can understand the value, relevance, and fidelity of simulation tools. Only then, test methods, programs, and laboratory test architectures can commence the migration to smarter test platforms and realize the benefits of new technologies.

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