Tech Tips: Structural Antenna Engineering for Tire Design

In recent years, the demand for intelligent and connected vehicles has led to the development of innovative solutions in automotive engineering. One of these solutions is using electromagnetic (EM) structural antennas integrated into tires, enabling communication between the vehicle and external devices. 

Tires operate under constant load and significant stress; they need to last for tens of thousands of miles driving across roads of varying quality in all manner of weather. Accurately predicting the life of a tire and in our case, of the antenna that has been installed therein, would be nigh impossible to do via physical test. This is where high fidelity and tightly coupled Multiphysics simulation comes into play. 

Designing such antennas can be challenging as it involves optimizing the antenna’s performance while also considering the mechanical constraints of the tire. This is where the CST Studio Suite offers a robust simulation environment for designing and analyzing electromagnetic structures, including antennas. 

Enhancing Structural Antenna Design with Advanced Simulation 

First, it is essential to understand the concept of EM structural antennas. These antennas are composed of conductive materials, such as metal embedded into a dielectric material, such as rubber. They can be designed to operate at specific frequencies and polarizations, which are determined by the dimensions and shape of the antenna. When integrated into a tire, they enable wireless communication between the vehicle and external devices, such as GPS systems, smartphones, and other vehicles. 

Step 1: Structural Simulation 

A tire is not, as one might initially think, just a rubber donut that one fills with air every couple thousand miles. The structure is a highly complex multi-layered assembly. All these layers are made up of different materials such as nylon, steel webbing and different types of rubber.  

By creating an accurate virtual representation that reflects this complexity, we can begin to perform a Multiphysics simulation of tire assembly in conjunction with the installed antenna. This allows us to perform the analysis at the worst loading case, which is when the tire rotation places the antenna at the bottom of the tire with maximum expected deformation, using the Tire Analysis Engineer Role on the 3DEXPERIENCE platform. 

The antenna, which is designed and optimized as a flat structure, is initially adhered to the un-deformed inner liner of the tire. Then we can apply the deformation vector to the full tire assembly as well as the antenna to generate the fully deformed device under test. 

Step 2: Electromagnetic Simulation 

The deformed assembly can directly be brought into the electromagnetic simulation environment where the regular electromagnetic simulation set-up occurs. The main steps will include: 

• Assigning appropriate material properties 
• Defining the excitation and boundary conditions 
• Setting up the solver 
• Localized Mesh Refinement 

Due to the nature of the problem where we have a deformed thin panel antenna on a relatively large structure, we choose to use our market-leading transmission line matrix (TLM) solver. We can then easily apply a very fine mesh in the proximity of the antenna, where this resolution is required to accurately mesh the geometry, while automatically reducing the mesh fidelity the further away from the antenna we get. The resulting mesh has 25 million cells and in order to efficiently run the simulation we make full use of cloud computing and GPU acceleration, which our time domain solvers can utilize to significantly reduce simulation times. 

Step 3: Process Automation 

Now that both the structural and electromagnetic simulations have been fully set up and tested, we can then perform a Multiphysics design of the tire. Rather than analyze the assembly for one tire rotation angle we can use Process Composer to couple the two physics and perform an automatic parameter sweep to simulate every possible rotational angle to ensure the antenna works well under all circumstances.
 

Drive Success with SIMULIA CST Studio suite 

When it comes to designing antennas, the SIMULIA CST Studio Suite offers a range of simulation tools that can model the antenna’s electromagnetic behavior and optimize its performance. Key capabilities include: 

• Multiphysics Simulation: Model electromagnetic and mechanical behavior of antennas to simulate the antenna’s deformation and stress distribution under various mechanical loads, such as the tire’s deformation under different driving conditions. This enables engineers to optimize the antenna’s mechanical design and ensure its reliability and durability. 
• Finite Element Method (FEM): Simulate the electromagnetic field distribution around the antenna and predict its radiation pattern. This allows engineers to optimize the antenna’s shape and dimension to achieve the desired performance. 
• Method of Moments (MoM): Simulate the antenna’s electromagnetic behavior in the presence of other conductive structures, such as the vehicle body. This helps engineers to ensure that the antenna is not affected by interference from other components in the system. 
• Design and Optimization: In addition to simulation tools, the CST Studio Suite also offers a range of design and optimization tools, such as parameter sweeps, optimization algorithms, and design of experiments (DoE). These tools enable engineers to explore different design options and identify the optimal design parameters for the antenna. 
• Post Processing: Analyze the simulation results and visualize the antenna’s electromagnetic and mechanical behavior and generate all manner of outputs that might be relevant. This includes 3D visualization tools, such as field overlays and cut planes, which enable engineers to visualize the antenna’s radiation pattern and field distribution. This helps engineers understand the antenna’s performance and identify potential issues. 

• Process Automation: The CST Studio Suite can help simulation structural and electromagnetic simulation to help perform a coupled Multiphysics design of experiment. Tools like the Process Composer can analyze the physics of the two and complete a parameter sweep across every rotational angle to ensure the antenna works well under all circumstances. 

Conclusion 

In conclusion, the design of electromagnetic structural antennas for tire engineering is a complex task that requires a robust simulation environment. The CST Studio Suite offers a range of simulation, design, and optimization tools that enable engineers to optimize the antenna’s performance while also considering the constraints of the tire. This allows the development of intelligent and connected vehicles to communicate wirelessly with external devices, leading to a more connected and efficient transportation system. 

SIMULIA CST STUDIO with TriMech Enterprise Solutions  

Our TriMech Enterprise Solutions team is experienced with implementing SIMULIA CST Studio, which can be installed as an in-house or cloud-based solution for globally dispersed enterprises.