Key Takeaways & Executive Findings
- •• Introduces a functionally gradient honeycomb non-pneumatic tire (NPT) design that synergistically improves multiple performance metrics. • The optimized NPT-OP achieves a 23.48% reduction in radial stiffness, 8.95% reduction in maximum spoke stress, and 16.86% reduction in spoke mass compared to the initial design. • Combines response surface modeling (RSM) with NSGA-II for efficient multi-objective optimization of honeycomb spoke structures. • Provides a theoretical and technical foundation for the structural design and optimization of gradient honeycomb NPTs, enhancing safety and performance.
Abstract
The spoke as a key component has a significant impact on the performance of the non-pneumatic tire (NPT). The current research has focused on adjusting spoke structures to improve the single performance of NPT. Few studies have been conducted to synergistically improve multi-performance by optimizing the spoke structure. Inspired by the concept of functionally gradient structures, this paper introduces a functionally gradient honeycomb NPT and its optimization method. Firstly, this paper completes the parameterization of the honeycomb spoke structure and establishes the numerical models of honeycomb NPTs with seven different gradients. Subsequently, the accuracy of the numerical models is verified using experimental methods. Then, the static and dynamic characteristics of these gradient honeycomb NPTs are thoroughly examined by using the finite element method. The findings highlight that the gradient structure of NPT-3 has superior performance. Building upon this, the study investigates the effects of key parameters, such as honeycomb spoke thickness and length, on load-carrying capacity, honeycomb spoke stress and mass. Finally, a multi-objective optimization method is proposed that uses a response surface model (RSM) and the Non-dominated Sorting Genetic Algorithm - II (NSGA-II) to further optimize the functional gradient honeycomb NPTs. The optimized NPT-OP shows a 23.48% reduction in radial stiffness, 8.95% reduction in maximum spoke stress and 16.86% reduction in spoke mass compared to the initial NPT-1. The damping characteristics of the NPT-OP have also been improved. The results offer a theoretical foundation and technical methodology for the structural design and optimization of gradient honeycomb NPTs.
1. Introduction
Automobile tires, integral components of vehicles, are sophisticated composite material structures [1]. Serving as a crucial element in the vehicle's propulsion system, the tire is the only component that interacts with the road. Its primary functions include bearing loads, generating ground forces, and mitigating ground disturbances [2]. Tires play a pivotal role in influencing vehicle handling and stability, ride comfort, and overall performance. For decades, traditional pneumatic tires have dominated the global tire market due to their advantages of low contact pressure, low energy loss, low mass, and low vertical stiffness [3]. However, traditional pneumatic tires pose potential risks, including those related to air leakage, unstable pressure, blowouts, and wear. According to statistics, 46% of highway traffic accidents were caused by tire hazards, with flat tires accounting for a staggering 70% of accidents [4]. Therefore, to ensure vehicle safety, tire manufacturers and relevant research institutes have been seeking practical and viable tire safety technologies.
Tire safety technology is a comprehensive technology that not only maintains the basic functions of a tire but also enhances safety or eliminates tire hazards altogether. Current technological approaches for improving tire safety involve either enhancing the safety of pneumatic tires or adopting nonpneumatic tires (NPTs). Pneumatic safety tires are currently used as emergency safety measures and are not suitable for prolonged driving. Therefore, research on NPT technology has received much attention in recent years.
The primary distinction between NPTs and traditional pneumatic tires is that NPTs use a support structure instead of inflation pressure. A typical NPT comprises three main components: the tire body, rim, and support structure. The support structure, a crucial element, absorbs impact and provides flexibility to the wheels under static and dynamic conditions [5]. Over several decades of research, various types of NPTs have been developed, notable examples being Tweel NPTs, mechanical elastic NPTs (MENPTs), and honeycomb NPTs. Tweel tires exhibit performance characteristics similar to those of pneumatic tires, making them suitable replacements in specific operating conditions [6–8]. The support structure of MENPTs, crafted from highly elastic metal, has an excellent abi
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Haichao Zhou, Haifeng Zhou, Haoze Ren, Zhou Zheng, Guolin Wang (2025). Performance Analysis and Multi-Objective Optimization of Functional Gradient Honeycomb Non-pneumatic Tires. Chinese Journal of Mechanical Engineering. https://doi.org/10.1186/s10033-025-01235-5
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Frequently Asked Questions
What is a functionally gradient honeycomb non-pneumatic tire?
It is a non-pneumatic tire design that uses a honeycomb spoke structure with a gradient variation in geometry or material properties to improve multiple performance aspects such as load-carrying capacity, stress distribution, and mass reduction.
How was the multi-objective optimization performed in this study?
The optimization used a response surface model (RSM) to approximate the relationships between design parameters and performance outputs, and then applied the Non-dominated Sorting Genetic Algorithm II (NSGA-II) to find the optimal trade-offs among conflicting objectives like radial stiffness, spoke stress, and mass.
What were the key improvements of the optimized NPT-OP compared to the initial design?
The optimized NPT-OP showed a 23.48% reduction in radial stiffness, an 8.95% reduction in maximum spoke stress, and a 16.86% reduction in spoke mass compared to the initial NPT-1, along with improved damping characteristics.
Why are non-pneumatic tires considered safer than traditional pneumatic tires?
Non-pneumatic tires eliminate the risks associated with air pressure, such as blowouts, air leakage, and pressure instability, which are major causes of tire-related accidents. They use a support structure instead of air, enhancing safety and reliability.
What is the significance of the gradient structure in the honeycomb spokes?
The gradient structure allows for a tailored distribution of stiffness and stress across the spoke, enabling simultaneous improvements in load-carrying capacity, stress reduction, and mass savings, which are often conflicting in uniform designs.
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