This study proposes a Bayesian optimization framework and a related subjective Bayesian update model for the open-hole tensile (OHT) strength design of laminated composites, considering empirical stacking sequence constraints. First, a surrogate model for OHT strength is constructed in terms of lamination parameters using a Gaussian process model, serving as the Bayesian optimization framework, based on experimental strength test results. Subsequently, multiple laminate candidates satisfying the empirical constraints are identified through batch Bayesian optimization using a genetic algorithm with efficient genetic operators, including gene repair strategies and adaptive mutation. To efficiently update the surrogate model, a subjective Bayesian updating method utilizing low-fidelity strength analysis results instead of data from additional strength tests is proposed. Here, “subjective” refers to the engineer’s judgment in defining the uncertainty range of the analysis results to ensure that the approximation accuracy is not compromised. This subjectivity is modeled using a subjective probabilistic framework using the three-point estimation method from the Program Evaluation and Review Technique, which defines pessimistic, most likely, and optimistic values. The Bayesian update process, guided by this subjective stochastic model, is applied to enhance the accuracy of the surrogate model for strength design. The effectiveness of the proposed method is demonstrated through OHT strength design examples of laminates.

Piecewise dynamic twist of rotor blades is studied as a method for reducing rotor power and improving rotor performance. A validated helicopter model is used to predict the rotor power at different flight states. The effects of the parameters of the piecewise dynamic twist, including the phase angle, amplitude, harmonic number, and location, on the rotor performance are investigated. The inboard blade locations with the 1/rev dynamic twist are the most efficient parts to reduce the rotor power at low advance ratios, and the outboard locations are better for high advance ratios. A 2/rev dynamic twist usually can save more power at high advance ratios. Larger twist actuation leads to larger rotor power reduction, while the actuation with fewer actuated piezoelectric patches is more efficient. The dynamic twist with six pairs of the actuated patches is appropriate which can balance the efficiency and power savings. By deploying a piecewise dynamic twist containing the 1/rev and 2/rev twists at the spanwise locations of 10%–40% and 60%–90% of the blade, the rotor power can be significantly reduced and the performance is improved, especially at high advance ratios. A power reduction of 9.0% can be obtained at an advance ratio of 0.375.