This paper highlights how recent advances in multibody dynamics simulation methods can efficiently address challenges in the realm of noise, vibration, and harshness (NVH) to enable an optimized foundation brake system design. 

Brake squeal, a primary concern in NVH analysis, is characterized by high-frequency vibrations caused by the interaction between foundation brake components. In addition to brake squeal, other issues such as judder, roughness, and moan can occur in automotive braking systems. These require detailed analysis and design changes to ensure optimal performance and a comfortable driving experience. 

Recent advances in commercial multibody dynamics software have significantly enhanced the ability to capture critical physical effects that occur in a foundation braking system. Two key effects have emerged as particularly important: one, the local and global structural deformation of brake components (rotor, caliper, and brake pads); And two, the contact force and friction variation between the pads and rotor, which is influenced by structural deflection or deformation of those parts under typical operating conditions. 

These effects need to be represented simultaneously and dynamically within a unified CAE model. In addition, the unsprung masses in the suspension and drivetrain interact with the foundation brake system components, so it is beneficial to analyze the entire “corner” or quarter-car as a system. Traditional FEA analysis methods offer high accuracy and detailed results, but it can be computationally expensive as well as lacking in the ability to efficiently characterize the non-linearity of suspension components such as rubber bushings and hydraulic damper. 

Multibody simulation enabled by “enhanced flexible contact interaction” addresses these modeling challenges efficiently. It offers fast solve time compared to transient FEA. Multibody models can be set up parametrically, so it is possible to reuse the same model for different vehicle programs just by changing parameters and 3D geometry, rather than repeating the detailed build process. Thus, a faster means of tuning the model to validate it against test-bench data is enabled. Additionally, through a downstream reduction process using the same basic multibody model, it is possible to implement a real-time digital twin. 

This paper demonstrates the end-to-end workflow of analyzing a complex brake NVH problem. We utilize Altair’s multibody dynamics solver, MotionSolve, together with its finite element solver, OptiStruct, to show the dynamic response of a quarter-car model that includes a high-fidelity 3D representation of the foundation braking system and suspension. We demonstrate how Altair's multi-physics simulation platforms, Simlab and HyperWorks, enable an integrated approach to streamline the analysis process. This workflow makes it possible to explore more designs in a shorter duration, leading to enhanced brake performance and a more refined driving experience.

The environment is an increasingly important concern today and no economy is unaffected.

Brake dust particle emission is becoming more and more important during brake development due to upcoming legislation and manufacturer responsibility to develop “green products”. Despite all effort that is put into research of the friction couple regarding compounding and interface dynamics, particles of different size, weight and chemical composition will still be generated. Assuming this, the key question is, where are these particles going to?

As braking is a complex process, depending on speed, vehicle weight, level of deceleration, as well as environmental conditions such as temperature and humidity which influence the type and nature of the particles emitted, ranging from very fine to coarse. Depending on their nature, these emissions can end up in the environment in the draining water or in the air we breathe. In the literature there are more and more studies about airborne particles; they all show that mainly emitted particles during braking have a distribution which varies with the braking conditions from nano to micro scale particles.

Altair Engineering as a company specialized in numerical solutions and high-performance computing. Companies specialized in numerical solutions are also challenged to identify which method would be the most suitable to study the trajectory evolution of these particles after their emission. In this context Altair Engineering proposes the use of the Discrete Element Method (DEM) used in the EDEM software. The DEM method is suitable for studying the behavior of a very large number of particles interacting with each other and with their environment. The method can be easily coupled with other numerical solutions such as CFD. Also, the numerical characteristics of the problem require a good strategy to solve the equations in an acceptable time.

In this paper a workflow combining CFD (from Altair) and EDEM is shown with the target to follow particle evolution around the brake system in test bench environment. This numerical solution will bring an improvement to the standard legislation (test bench) by making it possible to understand the behavior of the particles around the brake system. the standard provided only measuring the quantity of particles emitted and measured relative far from the brake system.

The environment is an increasingly important concern today and no economy is unaffected. This also applies to the friction braking system industry, because of the particles emitted during each braking process. As braking is a complex process, depending on speed, vehicle weight, level of deceleration, as well as environmental conditions such as temperature and humidity which influence the type and nature of the particles emitted, ranging from very fine to coarse. Depending on their nature, these emissions can end up in the environment in the draining water or in the air we breathe. In the literature there are more and more studies about airborne particles; they all show that mainly emitted particles during braking have a distribution which varies with the braking conditions from nano to micro particles. For these reasons, Mercedes Benz AG is looking for suitable methods to understand and analyse the braking emissions and countermeasures to recover the emitted particles. Simulations could support here to provide meaningful information regarding brake dust flow also it can enlarge the view including surrounding components and the full vehicle airflow in the wheel housing. Companies specialized in numerical solutions are also challenged to identify which method would be the most suitable to study the trajectory evolution of these particles after their emission. In this context Altair Engineering proposes the use of the Discrete Element Method (DEM) used in the EDEM software. The DEM method is suitable for studying the behaviour of a very large number of particles interacting with each other and with their environment. The method can be easily coupled with other numerical solutions such as CFD. The numerical characteristics of the problem require a good strategy to solve the equations in an acceptable time. In the presentation, a numerical model representing a vehicle wheel-housing and the braking system will be presented to visualize the evolution of the emission trajectories for certain braking scenario. The aim of these studies is to evaluate if the numerical models are solvable and if their results bring a better understanding of the problems encountered. Eventually a simulation containing a countermeasure will be carried out to estimate the prediction of effectiveness of this measure.