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This paper aimed to investigate the energy absorption characteristics and damage mechanism of carbon fiber reinforced plastics/aluminum (Al‐CFRP) under radial impact. In this study, the damage mode of the hybrid tube is analyzed by falling hammer impact experiments, and the correctness of the finite element model is verified by comparing the experimental and numerical simulation results. Then, the damage mechanism of the hybrid tube under impact loading and the effects of the increase of the fiber angle, the wall thickness of Aluminum, and the number of outer CFRP layers on the impact resistance were analyzed according to the model. The comprehensive performance model of the hybrid tube was established by using the complex scale comprehensive evaluation method, and the genetic algorithm was used to optimize the hybrid tube and determine its optimal performance under radial impact load. The results show that the Al‐CFRP hybrid tube's overall stiffness and deformation resistance under radial impact is improved with the increase of the fiber angle, the wall thickness of the Al tube, and the number of outer CFRP layers. Combined with the parametric analysis of the numerical simulation results, a comprehensive performance evaluation model based on the complex proportionality assessment method (COPRAS) was developed and a genetic algorithm (GA) under back propagation (BP) neural network prediction was used. The optimal hybrid tube form with the best overall performance under radial impact was obtained using GA with BP neural network prediction. Highlights: The energy absorption characteristics of hybrid tubes under radial impact are investigatedA comprehensive performance evaluation model of hybrid pipe based on the complex proportional assessment method (COPRAS) is developedThe failure process and energy absorption mechanism of the hybrid pipe under radial impact are analyzedA genetic algorithm (GA) with backpropagation (BP) neural network prediction was used to obtain the hybrid pipe form with the best overall performance under radial impact [ABSTRACT FROM AUTHOR]

Damage can cause uncontrollable changes during the service of a structure, leading to a reduction in mechanical properties and ultimately to structural failure. This paper presents an experimental and numerical study of the crashworthiness of thin‐walled Al/CFRP hybrid tubes with pre‐existing transverse compression damage under transverse impact loading. Experiments shows that initial damage has a more limited effect on the energy absorption capacity of hybrid tubes under impact loading, but has a greater effect on their deformation pattern and the evolution of damage. After impact, cracks on the surface of the damaged tube propagate into multiple, discontinuous cracks with a total length similar to the length of the tube. Conversely, only short cracks are generated on the intact tube. Subsequent finite element simulations demonstrate the validity and accuracy of a coupled multi‐loads model and explore the effect of different structural parameters (winding angle and number of CFRP layers, and thickness of Al tube) on the crashworthiness of the hybrid tubes. Finally, a multi‐objective snake optimizer algorithm (MOSO) was used to obtain an optimal hybrid tube structure for multiple loading conditions in order to minimize the effect of initial damage on the crashworthiness of the hybrid tube. In comparison to the simulation outcomes for the original structure, the peak crushing force (PCF) decreased by 28.46%, whereas the specific energy absorption (SEA) increased by 44.59%. Highlight: The effect of pre‐existing damage on the crashworthiness and deformation pattern of hybrid tube structures is investigated by means of experimental and numerical simulations.A multi‐step finite element model was developed using the restart method to realize the crashworthiness analysis of the hybrid tube under multiple load coupling conditions.The prediction accuracy of four surrogate models for the crashworthiness of hybrid tubes is compared and analyzed.The multi‐objective snake optimizer algorithm (MOSO) is proposed to obtain the optimum hybrid tube structure for multiple loading conditions. [ABSTRACT FROM AUTHOR]

Carbon fiber reinforced polymer is an effective solution for replacing metal materials and achieving lightweight, and both three‐dimensional (3‐D) braided composites and prepreg laminated composites have their strengths and weaknesses. Using only one forming process can be challenging to meet the performance requirements of structural components under complex operating conditions. To effectively reduce the production cost and cycle time of large structural components while ensuring the mechanical properties of the structure, this article proposes a novel three‐dimensional braided and prepreg‐layered (braid‐and‐lay) composite forming process that is studied in the context of metro bogies. First, the performance advantages of braid‐and‐lay composites were verified through experimental methods. Then, a multi‐scale analysis method, combining experimental and finite element analysis, accurately predicted the macroscopic elastic parameters of the three‐dimensional braided composite with an error of less than 10% compared to the experimental values. Finally, a structural optimization design of the braid‐and‐lay composite metro bogie was carried out based on the predicted elastic parameters. The results show that the mass of the structure was reduced by 15.33%, from 272.103 to 230.386 kg, while ensuring that the displacement and stress responses do not exceed the constraint range. Highlights: Proposed a braid‐and‐lay integrated composite forming process.A multi‐scale analysis method, combining experimental and finite element analysis, was used to predict the modulus.The effect of braiding parameters on modulus prediction was investigated.The influence of the forming process and structural parameters on the performance of the metro bogie was investigated.The lightweight design of the metro bogie is effectively realized. [ABSTRACT FROM AUTHOR]

To find a thin‐walled impact‐resistant structure with excellent crushing performance, a multi‐cell hybrid thin‐walled tube (MCHT) formed by winding carbon fibers around a multi‐cell Al tube was proposed. The structure is designed based on different structural parameters of the thin‐walled tubes exhibiting different crushing characteristics and damage modes. First, a finite element model applicable to MCHT is established, and the accuracy of the model is verified by quasi‐static axial pressure experiments. Second, the verified finite element model was used to study the variation law of the overall structural crushing performance by changing the structural parameters of MCHT, and the Al tube wall thickness was found to have the greatest effect on MCHT crushing performance, followed by the number of ribs and finally the inner circle diameter. Then, a theoretical prediction model of the mean crushing force of MCHT was established based on the principle of energy conservation, and the accuracy of the theoretical model was initially verified through experiments. Finally, to overcome the problem that the prediction error of the theoretical model is larger when the number of ribs is larger or the inner circle diameter is smaller, a correction function is constructed based on Pearson correlation coefficient analysis to further improve the generalization ability of the above‐mentioned theoretical model, and the maximum relative error is reduced from 37% to 14.61%. [ABSTRACT FROM AUTHOR]