Aircraft structural strength test is the most important verification method of aviation structure at present, and it is an indispensable and important link in the aircraft development process. At present, the measurement method of aircraft structural strength test is relatively simple, and only limited and discrete response data can be obtained, and it is difficult to obtain information during the whole process and the whole field of the test, which limits the comprehensive analysis and processing of data. In view of this, this paper proposes a data-driven virtual-real fusion algorithm to construct a digital twin model suitable for structural strength test by fusing simulation data and test data, so as to achieve high-precision prediction of the mechanical properties of test objects. The algorithm is divided into two stages: pre-training and real-time prediction. In the pre-training stage, the simulation data is used to train the Particle Swarm Optimization Random Forest (PSO-RF) model. In the real-time prediction stage, based on the error between the trained PSO-RF model and the experimental data, the Radial Basis Function Multi-Fidelity Surrogate (RBF-MFS) model is trained. Finally, by fusing the PSO-RF model and the RBF-MFS model, a digital twin model of the test object is constructed. The results show that the accuracy of the model on the test set is basically about R²=0.97, and the calculation time on the 330 000 grid nodes is only 0.8 s, and the prediction error of the model is less than 10% for the danger area of the wing box segment, which meets the needs of practical engineering applications and provides a reference for the digitization of aircraft structural strength tests.

This study investigates the failure behavior of open-hole Variable-Stiffness Composite (VSC) laminates. A fiber placement path was fitted based on the distribution of principal stresses, and an anisotropic and quasi-brittle phase-field model was developed to predict the damage evolution in VSCs. First, a direction-dependent crack surface density function was introduced into the unified phase-field framework to capture the anisotropic characteristics during crack propagation. Then, a phase-field driving force and damage constitutive relationship suitable for mixed failure modes were constructed, enabling the model to analyze coupled failure mechanisms. By implementing an alternate solution scheme and a layered element structure in the UEL subroutine, the phase-field model was numerically solved using ABAQUS. To verify the accuracy and applicability of the model, damage and failure analyses were conducted on single-edge-notched plates made of straight-fiber and curved-fiber composites, respectively. The results indicate that the model can reasonably predict the mechanical behavior and crack propagation paths of composite laminates. Finally, the model was used to simulate the tensile failure and damage evolution of open-hole plates with constant and variable stiffness. The results show that the predicted crack paths agree well with experimental observations, and the tensile strength of the variable stiffness plate is significantly improved compared to that of the constant stiffness plate.

To study the ditching performance of civil aircraft in wave conditions, the finite volume method of computational fluid dynamics is used to solve the unsteady incompressible RANS equation. Based on the relevant requirements and suggestions of airworthiness regulations, VOF method, whole dynamic grid method, stokes fifth-order wave model and adaptive grid technology are used to construct the numerical simulation model. The research object is airbus A320-200. Firstly, the ditching process of aircraft in the calm water and wave condition is compared and analyzed. The results show that the maximum horizontal overload is 2.42 g in the wave condition, which is 1.09 times of that in the calm condition. The maximum vertical overload is 4.82 g, which is 2.82 times of that in the calm water condition. In both cases, cushion effect and diving phenomenon are obvious. In the initial stage of impact, the aircraft is affected by water suction. In the wave condition, jumping phenomenon appears, but does not have apparent effect on the ditching process. Secondly, the influence of wave factors on water ditching performance is studied. The results show that with the increase of the wave height, the maximum horizontal and vertical overload increase. With the increase of the wave length, the maximum vertical overload decreases. With the increase of the wave height and length, the maximum sinking velocity increases.