The performance models are the critical step for condition monitoring and fault diagnosis of diesel engines, and are an important bridge to describe the link between input parameters and targets. Large-scale experimental methods with higher economic costs are often adopted to construct accurate performance models. To ensure the accuracy of the model and reduce the cost of the test, a novel method for modeling the performances of marine diesel engine is proposed based on deep neural network method coupled with virtual sample generation technology. Firstly, according to the practical experience, the four parameters including speed, power, lubricating oil temperature and pressure are selected as the input factors for establishing the performance models. Besides, brake specific fuel consumption, vibration and noise are adopted to assess the status of marine diesel engine. Secondly, small sample experiments for diesel engine are performed under multiple working conditions. Moreover, the experimental sample data are diffused for obtaining valid extended data based on virtual sample generation technology. Then, the performance models are established using the deep neural network method, in which the diffusion data set is adopted to reduce the cost of testing. Finally, the accuracy of the developed model is verified through experiment, and the parametric effects on performances are discussed. The results indicate that the overall prediction accuracy is more than 93%. Moreover, power is the key factor affecting brake specific fuel consumption with a weighting of 30% of the four input factors. While speed is the key factor affecting vibration and noise with a weighting of 30% and 30.5%, respectively.

As there is increasing usage of composite components with a closed‐end shape, filament winding technology has been applied extensively in engineering practice. However, the residual stresses are readily caused by process parameters in composite manufacturing process. Hence, it is necessary to design the reasonable process parameters for obtaining the expected residual stresses. This study proposed a reverse derivation method to design the winding tension based on the residual stress model of the composite cylinder. To analyze the development of residual stresses, the thermal deformation behavior and a micromechanics model of resin shrinkage are considered to calculate thermal strains and instantaneous shrinkage strains of the hoop wound cylinder during the curing process. Combining the contribution of winding tension to the stresses, the simple model of residual stresses is established based on the superposition principle. Then inversely solving the analytic model, the design method of winding tension is illustrated to guarantee that the hoop wound cylinder with an inner liner has a uniform residual hoop stress. The model accuracy of residual stresses is validated by the destructive slitting experiment. The result indicates that the present model can be used to estimate the residual stresses and design the winding tension for the hoop wound cylinder.

The composite tape winding process, which utilizes a tape winding machine and prepreg tapes, provides a promising way to improve the quality of composite products. Nevertheless, the process parameters of composite tape winding have crucial effects on the tensile strength and void content, which are closely related to the performances of the winding products. In this article, two different object values of winding products, including mechanical performance (tensile strength) and a physical property (void content), were respectively calculated. Thereafter, the paper presents an integrated methodology by combining multi-parameter relative sensitivity analysis and single-parameter sensitivity analysis to obtain the optimal intervals of the composite tape winding process. First, the global multi-parameter sensitivity analysis method was applied to investigate the sensitivity of each parameter in the tape winding processing. Then, the local single-parameter sensitivity analysis method was employed to calculate the sensitivity of a single parameter within the corresponding range. Finally, the stability and instability ranges of each parameter were distinguished. Meanwhile, the authors optimized the process parameter ranges and provided comprehensive optimized intervals of the winding parameters. The verification test validated that the optimized intervals of the process parameters were reliable and stable for winding products manufacturing.

As an inevitable issue in the filament winding technology, the process-induced friction has gained increasing attention. The purpose of this study is to illustrate the experimental investigation of friction between prepreg tape and hot compaction roller in prepreg tape hoop winding system. Based on the modified version of Howell’s equation, the friction model is established to offer an indirect method for measuring the frictional coefficient during the actual composite fabricating process. Three types of prepreg tapes, namely T300/Y69 unidirectional prepreg tape, T300/DFQS-3 and BWT260-82/DFQS-3 orthogonal prepreg tapes are selected to discuss the effect of process parameters on friction under different processing conditions. The experimental results reveal that the friction behavior transfers from resin-dominated friction to fiber-governed friction as the temperature rises. Besides, acceleration of the spindle speed on the frictional coefficient can be markedly improved due to the increase of resin strain rate. Meanwhile, the fiber has a stronger ability to increase friction than resin. It is also observed that the friction plays a role in amplifying the winding tension by comparing the winding tension with the outgoing winding tension.