A Modified Test Vehicle Incorporating Distance from Neutral Point (DNP)-Induced Strain Gradients for Single-Specimen Fatigue Life Assessment of Solder Joints

초록

In this study, a Modified Test Vehicle (MTV) was developed to evaluate multiple strain conditions within a single specimen by exploiting strain gradients associated with different distances from the neutral point (DNP). Cyclic four-point bending tests were performed under displacement-controlled conditions, and strain amplitudes were quantified through finite element analysis (FEA). Using the Coffin-Manson model, a strain-life (epsilon-N) curve was generated by comparing experimentally measured fatigue lives with FEA-derived strain amplitudes. The validity of the calculated Coffin-Manson curve was subsequently tested under an independent displacement condition, demonstrating the consistency of predicted and measured fatigue lives. The proposed MTV approach enables efficient and representative fatigue life assessment of solder joints, offering improved predictive accuracy while reducing specimen requirements and overall testing complexity.

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