ABSTRACT Aiming at addressing the uneven pesticide distribution when spraying high-spindle apple trees, the parameters of a homemade profiling boom sprayer were analysed, and the optimal parameter combinations of the profiling sprayer were determined. Fluent was used to simulate the spray for various parameter values. The goodness of fit (R2) with experimentally measured data was 0.9270, which verified the accuracy of the numerical simulations. The response surface methodology (RSM) method was used to obtain optimal parameter values from the simulations, and the effective collection rate and spray distribution coefficient of variation were introduced as response values. A sprayer prototype was manufactured based on the optimal parameters determined by RSM analysis, and the results were verified by vertical droplet distribution tests. The results showed that the spray quality increased by 0.7%, 0.9%, and 0.3% for the three best parameters combinations, the droplet distribution was more uniform, and the effect of the profiling spray was better than that of the control tests. The results can provide guidance for the design of sprayers for orchards, and the optimal combination of parameters can provide a basis for subsequent research on precision modelling of profile spraying.

Abstract To improve the crashworthiness and energy absorption of thin-walled tube structures, a bionic thin-walled tube was designed based on the structural characteristics of antler osteon and the principle of structural bionics and had the same inner and outer diameters and the same gradient thickness as antler osteon. A nonlinear finite element method is used to simulate the crashworthiness of a thin-walled tube with equal gradient thickness variation (EGTTS) under axial and oblique loads. The crashworthiness of EGTTS-7 (Egtts with 7 layers) was evaluated using the complex proportional assessment(COPRAS). A multi-objective particle swarm optimization (MOPSO) algorithm was used to optimize the EGTTS-7 and the Pareto boundary was used to obtain the optimal structure parameters of the EGTTS-7 by using the loading angles of 0°, 10°, 20°, and 30°. It is found that the crashworthiness of the EGTTS is best when the axial load weight factor of the case is large. Compared with EGTTS and circular tubes(CT), F max can be reduced by up to 50.1% and EA can be increased by up to 22.7%.

Anstract Selective Laser Melting (SLM) is one of additive manufacturing techniques which enable to build a complex structure model layer by layer with 3D CAD software. However, a higher research cost makes it hardly carry out by a traditional methodology, the best way to solve the problem is using simulation software. This paper aims to find an optimal processing parameters combination for a specimen with the smallest distortion and lowest residual stress through Simufact Additive (SA) software. Simulation results under an optimal processing parameters, which led to a smallest value of distortion and residual stress, was the combination of scan power with 300W, scan speed with 1.3m/s, scan interval with one spot diameter (0.12mm) and heat treatment holding time with 4h. In addition, the calculation results provide a novel study method to verify the influence of different processing parameters on Inconel 718 alloys fabricated by SLM.