Constitutive Model of Duplex Stainless Steel: Experimental Investigation and Genetic Algorithm-Based Parameter Calibration

Duplex stainless steel (S22053) is increasingly favoured in construction and marine engineering due to its superior corrosion resistance, toughness, and high strength-to-weight ratio. This study presents a comprehensive investigation into the mechanical behaviour of duplex stainless steel under both monotonic and cyclic loading. First, monotonic behaviour is characterized, and the applicability of existing constitutive models is verified. Addressing the complexity of parameter identification for the cyclic constitutive model, a genetic algorithm (GA)-based calibration framework for the Chaboche model is proposed. This approach overcomes the subjectivity and inefficiency of traditional manual fitting. The proposed method is validated against experimental hysteresis curves, demonstrating high accuracy and providing a reliable basis for the seismic design of duplex stainless steel structures.