An Interval Spline Finite Point Method for Size-Dependent Mechanical Behaviors of Defective Functionally Graded Material Nanobeam

•The defect characterization model of functionally graded material (FGM) nanobeam is constructed based on interval mathematics.•An interval spline finite point method is presented to investigate the mechanical behavior of FGM nanobeam with defects.•A gradient-based vertex strategy is presented to improve the efficiency of predicting the bounds of mechanical response.