DESIGN OF HYBRID SETUP FOR DETERMINATION OF MECHANICAL PROPERTIES OF SERVICE EXPOSED MATERIALS USING SMALL PUNCH TEST AND FEM

Abstract

The accurate determination of mechanical properties for materials exposed to harsh service conditions is critical for ensuring the safety, reliability, and extended operational life of components in industries such as nuclear power, aerospace, and oil and gas. Traditional mechanical testing methods often demand large material volumes, which is impractical for in-service components or hazardous materials like irradiated specimens. The Small Punch Test (SPT) offers a miniaturised, semi-nondestructive alternative, yet its standalone application is limited by reliance on empirical correlations and the complex biaxial stress state, hindering direct property extraction. This research addresses these limitations by proposing a novel hybrid experimental-numerical setup that integrates SPT with the Finite Element Method (FEM). Our methodology involves a meticulously designed hybrid setup that combines a miniaturised SPT fixture with high-precision extensometers for accurate punch displacement measurement. The iterative optimisation process, managed through ABAQUS routines, enables the extraction of fundamental material properties. Through rigorous validation and case studies, the hybrid SPT-FEM approach demonstrated significant improvements in material property characterisation. Finite Element Analysis (FEA) results, including load-displacement curves and deformed specimen shapes, showed strong agreement with experimental data. Notably, FEM analysis helped refine empirical correlations, leading to improved estimations for ultimate tensile strength. The setup's efficacy was validated across diverse service-exposed materials, including AL6082 alloy & Cr-Mo Steel. This research transforms the Small Punch Test from a qualitative screening tool into a robust, quantitative method for material characterisation, particularly for scenarios with limited or hazardous sample availability. The hybrid SPT-FEM setup provides critical insights into material degradation, enabling more accurate fitness-for-service assessments and reliable life extension predictions for ageing industrial infrastructure.