基于优选小波分量的收获机作业部件载荷谱加速编辑方法

    Acceleratedediting for the load spectrum of harvester operational units using optimal wavelet components

    • 摘要: 为提高实验室场景下开展收获机械耐久性试验验证的效率,该研究以联合收获机作业部件载荷为例,开展载荷谱加速编辑方法分析。在传统基于小波分解的加速编辑方法基础上,讨论了不同小波分量差异选取对加速编辑效果的影响,尝试利用伪损伤比例界限对小波分量进行筛选,并通过极值差方法对小波分量中高损伤贡献片段进行识别,形成了基于优选小波分量的载荷谱加速编辑方法。利用实测载荷数据将该方法与基于小波分解和时域损伤保留两种方法进行了对比分析,结果表明,在伪损伤保留比例趋近一致的条件下,基于优选小波分量的加速编辑方法能够得到更精简的加速结果,以喂入搅龙载荷为例,在95%和98%伪损伤保留比例下,本文方法能够在传统小波分解方法基础上,将信号压缩比提升11.59和15.72个百分点。本文所述方法对于收获机作业部件载荷具备通用性,在其他行业领域的结构耐久加速试验场景下同样具有应用潜力。

       

      Abstract: This study aims to improve the efficiency of durability testing, and then verify the harvesting machinery in laboratory scenarios. The accelerated editing was investigated on the load spectrum, according to the operating loads of combine harvester components as an example. The testing efficiency was further improved to reduce the costs for better consistency in the load spectrum loading between field and laboratory bench tests. Different wavelet components were selected to accelerate the editing using traditional wavelet decomposition. The threshold of pseudo-damage ratio was used to filter the wavelet components. The high contribution of damaged segments was identified in the wavelet components using the extreme difference method. Among them, the peak and valley values were extracted from the reconstructed wavelet components. Differences among adjacent extreme values were calculated after reconstruction. The threshold was then applied to discriminate the specific damage segments during extraction. An accelerated editing of the load spectrum was developed using optimal wavelet components. A case study was selected as the operating components of the feeding system in a combine harvester. The torque load was compared with the wavelet decomposition and time-domain damage retention. The results indicated that there was a greater variation in the signal frequency components and statistical features represented by different wavelet components, compared with the traditional acceleration editing of wavelet decomposition. Therefore, the negative impact of acceleration editing was also found in the indiscriminate identification of the damaged segment for each wavelet component. The acceleration editing was potentially improved to exclude the specific high-frequency wavelet components from the damage segment calculation. The wavelet components were then filtered, according to the pseudo-damage ratio between each wavelet component and the original load. There was a more precise and flexible identification of damage segments using extreme differences. Particularly for the boundaries of damage segments, compared with the time-domain window and the envelope damage segment identification. The periodicity of load cycles was achieved within the extracted load segments, in order to further enhance the accuracy of damage segment identification. The accelerated editing with optimized wavelet components was achieved in the more concise acceleration under the condition where the pseudo-damage retention ratios were nearly consistent. Taking the header auger load as an example under 95% and 98% pseudo-damage retention ratios, the acceleration values of the current wavelet decomposition were improved by 11.59 and 15.72 percental points, respectively, compared with the traditional. The acceleration editing with the optimized wavelet components also demonstrated better applicability to the load of drive shafts in the critical operating components of the feeding system. The signal compression ratios increased for the reel, header, and conveyor loads by 6.77, 12.44, and 20.19 percental points, respectively, under the relatively consistent levels of pseudo-damage retention, compared with the traditional. The better-accelerated editing of the load spectrum also exhibited better versatility for the different loads of operational components. The potential applications can also be found for the accelerated testing of structural durability scenarios in industrial field.

       

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