This post on Innovation Intelligence is written by Antti Jussila, Director of Sales & Marketing at ThermoAnalytics, developer of RadTherm for thermal analysis. ThermoAnalytics is a member of the Altair Partner Alliance.
The Case for Brake Thermal Modeling
Your car’s brakes are under constant strain from heat, which can be managed in one of two ways: 1) dissipation and/or 2) storage. Either the heat flows in some manner, or it is safely absorbed as energy or thermal inertia within the braking system to be dissipated later. When either is not done properly, the braking system deteriorates prematurely or in unpredictable ways.
Modeling the performance of a brake system in the design phase, if done completely and correctly, would identify any potential thermal issues long before they could occur, and even before the brake system is manufactured. By doing so, the manufacturer prevents not only liability or dissatisfaction from future car owners with underperforming brakes, but also saves considerable time and cost throughout the design cycle in some obvious, and some not-so-obvious ways.
One of the many benefits of using sophisticated technology to analyze and model real-world scenarios is the ability to prototype virtually — i.e., emulate real-world conditions via computer simulation to cover all of the important design space and operating scenarios. This level of testing would not be practical with physical prototypes. Accurate modeling protects a carmaker from the implicit need to “over-design” or “over-manufacture,” directly saving material costs in the manufacture of components, including brakes.
Real-World Modeling for Real-World Reliability
Not all modeling tools are the same. Many traditional modeling tools rely on simplistic assumptions for modeling the actual performance of a car’s brake system as it will occur in the real world. As a result, such tools return incomplete or inaccurate data and can cause a designer to create a sub-optimal design.
Some common mistakes that are made in the modeling process include:
- Reliance on steady-state analysis, when transient analysis is required. In the real world things are dynamic cars are used for quick trips one day and long treks on another, during which braking intervals vary widely. The amount of time between significant braking events can have a dramatic effect on how a braking system manages heat spikes. Traditional tools typically do not account for these real-world, transient variances, so they are not modeling truly dynamic situations.
- Not taking a multiphysics approach. There are, concurrently, many factors affecting the heating and cooling of brake systems, including the conduction of frictional heating through the brake components as brakes are applied, the radiation of heat between nearby objects, and airflow convection that can have a cooling effect. Conventional modeling tools may not fully account for all of these factors, so obtaining a robust analysis will require co-simulation through the coupling of multiple tools to fully simulate the entire braking process. Anything less than full simulation could result in design deficiencies.
- Using a one-dimensional (1D) tool to simulate a three-dimensional (3D) problem. Whether it’s the way heat radiates through multiple paths, is conducted along different axes, or is dissipated via complex airflow, heat is very much a 3D phenomenon. It’s nearly impossible to accurately simulate heat performance with 1D modeling software.
Modeling Early and Often
The earlier in the concept design phase of a braking system that modeling and analysis is begun, the greater the probability of success during the actual design/engineering phase. The earlier simulation is begun, the more complete and accurate the understanding of the actual performance of the braking system in the real world. It’s never too early to examine the entire picture!
Perhaps counter-intuitively, the introduction of full 3D, transient analysis into the design phase actually saves time and cost, as it allows the engineering team to identify issues and opportunities before a braking component is even built — in other words, before significant design and material costs are incurred.
A brake system undergoes significant, continuous and ever-changing heat stress during a normal drive cycle. Modeling that stress accurately, early and often will save time and costs in the short term, save the lifespan of the braking system in the long term, and perhaps even save lives in the extreme case.
If nothing else, getting smarter about design choices through analysis and modeling will help manufacturers make more educated decisions. How and where to make weight and material decisions in braking systems while meeting stringent enterprise-wide fuel efficiency standards and safety requirements is becoming increasingly important.