PSI - Issue 75

Said Allouch et al. / Procedia Structural Integrity 75 (2025) 299–310 S. Allouch / Structural Integrity Procedia (2025)

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Transferring load programs between different types of BiAx machines, particularly from an inner drum to an outer drum (or vice versa), is not recommended and can lead to inaccurate results. This is because the load application mechanisms are fundamentally different and transferring a load program from one machine type to another could lead to erroneous test results.

4.5. Wheel Size

The wheel size plays a significant role in determining the appropriate load programs for testing. From past LBF experiences the wheel sizes are divided into specific groups: 18" - 19", 19" - 20", 20" - 21", 22", and 23". Within each group, the deviation in wheel size is acceptable, ensuring that the load distribution remains consistent. For the wheel width, deviations of ±0.5” are generally considered without influencing the load program. The deviation between 18" and 19", 19" and 20", or 20" and 21" is small enough that a single load program can be used across each respective group. This means that the load applied to a wheel in the 18" - 19" range will be similar to that applied to a 19" wheel, and similarly, a load program designed for 19" - 20" wheels can be used for a 20" wheel. However, the transition from 18" to 20" introduces a larger deviation. The increase in size is more significant and impacts on the load distribution, which requires a new load program for the 20" wheel. For the 22" and 23" wheels, the size difference is substantial enough that individual load programs must be used for each of these sizes. The load distribution for these wheels is distinct from that of the smaller sizes, and using the same load program for these larger wheels would lead to inaccurate results. 4.6. Tire brand The last influencing factor on the load file in testing it the tire, but its impact on the results is relatively minimal compared to other factors. Tire brands typically do not have a significant effect on the overall damage observed during testing. This is because most tire brands within a given category (e.g., passenger, performance, or commercial) generally share similar material compositions, construction techniques, and performance characteristics. As a result, when subjected to similar loading conditions, the damage patterns produced by different tire brands tend to be comparable. However, tire wear can vary from one tire to another, even when the tire brand is the same. This variation is influenced by several factors, such as the manufacturing process, rubber compound, tread design, and even the specific batch of tires. Additionally, the way a tire is worn can also be affected by the machine type used in the testing process. Different testing machines or loading conditions can result in varying patterns of wear on the tire, as load application, may differ between machines. 5. Influence of tire ratio, tire width and wheel design on load file development In the following a closer look is spent on the influence of the tire ratio, the tire width and the wheel design on the results of a fatigue evaluation of passenger car wheels. The tire ratio is another crucial factor that influences the load file, as it directly impacts the internal stresses experienced by the wheel. To understand this relationship, tire ratios can be categorized into specific groups for which a single load program remains valid. However, changes beyond these defined groups result in deviating loads, necessitating the creation of a new load program. The identified groups are as follows 60, 50, 35 to 45 and <35. This classification refers to the wheel forces. To investigate the influence of the tire ratio on the internal stresses on wheel measured by the flat track roll rig and the BiAx machine (ZWARP technology), a dedicated study was conducted. The development of the load program for one wheel with a tire ratio and the validity for other tires with other ratios. 5.1. Tire Ratio