Key Takeaways & Executive Findings
- •• A novel damage sequence interaction model couples matrix and void phases to accurately predict residual mechanical properties of fatigued materials. • Collision simulations show fatigue damage reduces vertical lift of moving metro vehicles by up to 9.17% and increases longitudinal compression of stationary vehicles by up to 33.15%. • Experimental validation via trolley collision tests confirms the constitutive model's accuracy for engineering applications. • The study underscores the necessity of incorporating fatigue damage in metro vehicle design and maintenance for enhanced safety.
Abstract
This study decouples the material microstructure into matrix and void phases. The undamaged constitutive is derived from the matrix phase, while the void phase contributes to damage evolution. A constitutive model is established by coupling the two. According to the void-phase evolution during damage, a damage sequence interaction model is proposed. Tests on new vehicles and vehicles in service materials yield stress-strain curves of materials without and with fatigue damage and measure the apparent elastic modulus. The damage sequence interaction model accurately predicts the residual mechanical properties of undamaged materials. A trolley collision test validates the constitutive model. Collision simulations at 25, 36, and 48 km/h reveal that compared with undamaged models, the maximum vertical lift heights of moving vehicles with fatigue damage are 4.54%, 3.74%, and 9.17% lower, respectively, and the maximum longitudinal compressions of stationary vehicles are 4.76%, 14.53%, and 33.15% higher respectively. This research emphasizes the importance of considering fatigue damage in vehicle design and maintenance. The damage sequence interaction model has high engineering application value, applicable to vehicle safety checks and design, and provides a reference for improving relevant standards.
1. Introduction
Metro vehicles operate in a complex and changing environment and are subject to shock and vibration loads from all directions, so they are prone to fatigue damage. Once the vehicle’s body material deteriorates or fails, it will pose a severe threat to the regular operation of the vehicle. Therefore, studying the mechanical properties of materials before and after damage can provide an essential basis for the maintenance and material selection of metro vehicles.
The commonly used material for subway vehicles is aluminum alloy. Many research results have been achieved on the mechanical properties of aluminum alloy materials [1, 2]. Ref. [3] carried out tensile tests of aluminum alloy materials at different loading rates and different stress states and selected appropriate constitutive models and ductile fracture criteria to characterize the mechanical properties of materials [4].
Scholars have proposed various damage models to describe the damage and fracture behavior of materials. The uncoupled fracture model separates the damage description from the essential stress-strain relationship of the material when describing the fracture behavior of the material and does not directly consider the damage variable in the material constitutive equation. Common uncoupled damage models include the Johnson-Cook [5] damage model, the McClintock [6] model, the Rice-Tracy [7] model, and the MMC [8] criterion. The GTN [9] model based on micromechanics is also a classical theoretical model to describe the plastic deformation and damage behavior of porous materials. The model can fully characterize the whole process of material elasticity, plasticity, and fracture [10–12].
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Wenyue Yuan, Tao Zhu, Bing Yang, Haoxu Ding, Xiaorui Wang, Quanwei Che, Jingke Zhang, Shoune Xiao, Cheng Lei (2025). Influence of Fatigue Damage on Collision Response of Metro Vehicles: Simulation and Experimental Study Based on Damage Sequence Interaction Model. Chinese Journal of Mechanical Engineering. https://doi.org/10.1186/s10033-025-01316-5
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Frequently Asked Questions
What is the damage sequence interaction model?
The damage sequence interaction model is a constitutive model that decouples material microstructure into matrix and void phases. It couples the undamaged constitutive behavior from the matrix phase with damage evolution from the void phase, accurately predicting residual mechanical properties after fatigue damage.
How does fatigue damage affect metro vehicle collision response?
Fatigue damage reduces the maximum vertical lift height of moving vehicles by up to 9.17% and increases the maximum longitudinal compression of stationary vehicles by up to 33.15% compared to undamaged models, as shown in collision simulations at 25, 36, and 48 km/h.
What experimental validation was performed?
A trolley collision test was conducted to validate the constitutive model. The test results confirmed the model's accuracy in predicting collision responses of metro vehicles with fatigue damage.
Why is considering fatigue damage important in vehicle design?
Fatigue damage significantly alters the mechanical properties of materials, affecting vehicle safety and performance. Incorporating fatigue damage in design and maintenance ensures structural integrity and improves safety standards.
What are the practical applications of this research?
The damage sequence interaction model has high engineering application value, applicable to vehicle safety checks and design, and provides a reference for improving relevant standards in the rail transit industry.
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