Introduction
In today’s fiercely competitive racing landscape, lap time simulation provides teams with invaluable insights into their car’s potential performance on the track. By leveraging a combination of real-world data and advanced computer models, teams can carefully analyse various factors such as aerodynamics, suspension settings, and tyre behaviour to fine-tune their setup. This predictive tool allows teams to explore different scenarios and strategies, ultimately aiming to optimise performance and gain a competitive edge. Whether it’s finding the ideal balance between speed and tyre wear or maximising cornering grip, lap time simulation empowers teams to make informed decisions that can make all the difference in strategy for race day.
Types of Lap Time Simulation
Lap time simulations come in various forms, each tailored to suit different needs and objectives of what is being looked at. There are 4 main types of lap time simulations:
- Steady-state simulations:
- This approach is simple and assumes pure lateral and longitudinal dynamics. This makes it easy to calculate and incurs a low computational cost. It also requires a small set of parameters for investigation, streamlining the analysis process
- Quasi-static simulations
- This method is widely used for predicting aerodynamic gains, power unit maximum deployment, and primary mechanical configurations influenced by aerodynamics. It is useful in predicting variations in grip levels and offers sensitivity analyses across various parameters including power, mass, and grip. However, it doesn’t take into account time-dependent parameters so it doesn’t account for transient responses. It breaks the circuit into smaller segments based on length and radius, assuming steady-state conditions within each segment and applying D’Alembert’s principle to determine the car’s motion state. It overlooks damping and unsprung mass oscillation effects as well as transient effects such as direction changes and tyre heat build up. Nevertheless, its computational cost remains low.
- Transient/Dynamics simulations
- This method involves integrating the full equations as a function of time, taking into account the time response, directional changes, oscillations, and fluctuations. This approach requires a controller to represent a driver and it allows for damping effects and transient modelling. This approach comes with a significant cost and takes time to run. Typically, it is used in optimising energy deployment or tyre conservation strategies, as well as understanding systems with time-dependent responses.
- Multibody system simulations
- Similar to transient simulation, this approach takes into account a suspension model that is connected to the chassis. However, it has a larger computational cost because of the increased number of equations required to model the system accurately.
Check out Lap-time Simulation with ChassisSim course HERE!
Within lap time simulation, there are 3 types of simulations that can be ran:
- ‘Track’ lap time
- Straight line simulation: to assess the Aero Balance, Ride Height, camber/plank height at the end of straight at any particular speeds
- Apex simulation: to assess the Mechanical balance, Roll
Source: a sample from ChassisSim & MoTeC
Role of rebalancing
Rebalancing is the name given to each setup that is changed to be compared. To make fair comparisons the rebalance parameters stay the same or similar to the reference conditions. For example, changing a set up with a lower front ride height will be faster from an aerodynamic perspective but the front flap would need to be removed to bring it to the baseline aero balance.
To be in a more representative vehicle state, it should be in a combined (lateral and longitudinal) state.
The main parameters to consider during rebalance:
- Aero Balance → adjusting front flap/ride height
- Mechanical Balance → adjusting rear ARB
- Roll Stiffness → adjusting front and/or rear ARB
- Camber End of Straight → adjusting static camber
- Plank Height End of Straight → adjusting static ride height
Simulation correlation
It is important to find correlations between simulations to be able to pinpoint the model’s weaknesses. The correlation process, when applied to various factors, not only enhances future results but can lead to more precise predictions. Moreover, it can allow feedback loops with aerodynamicists and tyre engineers, particularly when aero maps or grip levels are not as expected. For Vehicle Dynamicists, the focus of correlation lies in two main areas:
- Lap time simulation:
- The aim is to identify factors that can be correlated to achieve more accurate sweep states during race events.
- Suspension behaviour and modelling:
- In suspension behaviour and modelling, the goal is to detect setup misalignments and potential model weaknesses.
These correlations are typically shared among aerodynamicists, tyre engineers, race engineers, and power unit groups, ensuring all relevant stakeholders are informed of potential miscorrelations. In the Vehicle Dynamics in F1 course, Course Leader Marc Olle Bernades covers these topics in more detail.
Check out Vehicle Dynamics in F1 course HERE!
ChassisSim
One popular commercial software that is used in the industry is ChassisSim. It is a transient lap time simulation software capable of solving full equations of motion and therefore integrates as a function of time. It also accounts for time response modelling (changes in direction, oscillations and fluctuations) which is useful for transient responses such as kerb riding/ optimising fuel consumption/energies. It requires a controller (driver) allowing for damping effects unlike quasi-static solvers (as covered earlier). ChassisSim usually runs track simulations but allows tracks to be modelled as open loop for straight line simulations and oval for apex simulations.
In the Lap Time Simulation course, Course Leader, Marc Olle Bernades provides a tutorial on how ChassisSim works and explains in detail the importance and steps required to conduct lap time simulations.
There are also excellent articles and blogs written by Danny Nowlan, the Owner and Director of ChassisSim Technologies, as resources for beginners to understand how the software works.
Watch this video: ChassisSim Motorsport Talks!
Conclusion
Lap Time Simulation is a playground for engineers and it is important to understand its role in performance optimisation for race events. Through detailed analysis and correlation techniques, lap time simulations serve as a cornerstone to enhancing the accuracy of predictions and refining the intricacies of vehicle dynamics. By identifying factors influencing lap times, engineers can uncover setup misalignments and potential model weaknesses, ultimately paving the way for more competitive and efficient race strategies. This iterative process fosters collaboration among engineers and highlights the pivotal role of lap time simulations in pushing the boundaries of performance excellence on the racetrack.
Meet the Author
Dheer is currently pursuing an MSc in Automotive Engineering at Cranfield University after completing his Bachelor’s in Mechanical Engineering in the US. He has built his experience through not only his studies but also by investing in his passion for high-performance vehicles through courses and hands-on opportunities. Outside engineering, he enjoys following F1 and other sports (like golf and football to name a few).
