Center for Railway Engineering

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Browsing Center for Railway Engineering by Author "Abdurhman Suleiman"

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    Analyzing the Effect of Multiaxial Stresses on the Structural Integrity of Composite Bogie Frames
    (Addis Ababa University, 2025-11) Abdurhman Suleiman; Mulugeta Habtemariam (Ph.D.)
    The increasing global demand for sustainable and efficient transportation has driven interest in replacing traditional steel railway components with advanced composite materials like Basalt Fiber-Reinforced Polymer (BFRP) due to their high strength-to-weight ratio, corrosion resistance, and cost-effectiveness. However, a comprehensive understanding of BFRP behavior under complex multiaxial stress conditions, typical of operational railway environments, remains limited, hindering confident application in critical components such as bogie frames. This research aimed to analyze the structural and fatigue behavior of a Y25 railway bogie frame made from BFRP, specifically focusing on developing a multiscale material model using DIGIMAT and ABAQUS, analyzing stress distribution under operational multiaxial load cases, predicting and comparing fatigue life with S355 steel, assessing failure behavior using the Hashin Failure Criterion, and evaluating strength-to-weight performance. The study employed a simulation based approach, selecting a 60% fiber volume fraction plain weave BFRP laminate, generating its homogenized properties, applying manual geometry modifications to an original steel bogie frame, and performing structural simulations in ABAQUS under EN 13749-defined multiaxial loading conditions, with fatigue life predicted using FE-SAFE and damage onset assessed via Hashin-based failure analysis. Results demonstrated a significant 75% weight reduction from 892 kg to 223 kg for the BFRP frame. Under multiaxial loading, the BFRP bogie maintained sufficient stiffness with stresses remaining within allowable limits, while fatigue life prediction showed a remarkable improvement: for example, in Case 2 the steel bogie frame failed at 594,292 cycles, whereas the BFRP frame exceeded 50 million cycles. Similarly, across all load cases, steel fatigue life ranged between 0.59–9.97 million cycles, while the BFRP consistently survived beyond 50 million cycles, confirming its superior durability. Hashin failure analysis also showed delayed damage onset in BFRP compared to steel, highlighting the material’s ability to withstand operational stresses without premature failure.