Time-domain random vibration analysis method of pipeline based on time-frequency conversion
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摘要:
减振结构的阻尼效果是管路振动设计的重点,传统频域随机振动计算方法考虑阻尼卡箍非线性因素较为困难。基于时频转换理论,提出了利用时域随机化方法将随机振动载荷谱转换为满足高斯分布的时域振动信号后进行动态计算的管路时域振动分析方法。利用简支梁模型计算了频域随机振动结果与时域随机振动结果,验证了时域随机振动分析方法的可行性,采样位置振动应力均方根值与频域结果误差在5%以内。针对实际管路结构分析了时域方法与频域方法的结果差异,并通过等效阻尼比的计算证明了时域方法在实际设计中的应用优势,采用时域方法分析了阻尼卡箍的摩擦系数、预紧力和不同卡箍构型对管路振动应力均方根值的影响,结果表明,构型和预紧力对振动影响较大,而摩擦系数影响较小,时域随机振动分析方法的参数设定更加灵活,能够差异化研究各类结构参数对管路振动的影响,提高管路减振结构设计效率。
Abstract:Characteristics of damping structures are essential for pipeline vibration design. In traditional random vibration analysis, it is currently challenging to take nonlinear variables caused by damping structure into account. Based on the theory of time-frequency conversion, this paper proposes a time-domain dynamic analysis method that converts random vibration load spectrum into a time-domain vibration signal satisfying Gaussian distribution by using the time-domain randomization method. First, using a simple beam model, the reliability of the time-domain analysis method was demonstrated by comparing random vibration results in frequency-domain and time-domain analysis. Notably, there is a 5% discrepancy in the stress root mean square error between the two approaches. In addition, the difference between the time-domain method and the frequency-domain method is analyzed for the actual pipeline structure, and the advantage of the time-domain method in practical design is proved by calculating the equivalent damping ratio. Thereafter, it was analyzed that the influence of friction coefficient, preload of damping clamp and different clamp configurations on pipeline vibration by applying the time-domain analysis method. The results indicate that the configuration and preload have a greater influence on vibration, but the friction coefficient has a smaller influence. It is evident from the aforementioned analysis that the time-domain random vibration analysis method's parameter setting is more adaptable, allowing for a more thorough investigation of the effects of different structural parameters on pipeline vibration and an improvement in the damping structure's design efficiency.
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Key words:
- pipeline /
- random vibration /
- damping structure /
- time domain randomization /
- nonlinear factor
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表 1 随机振动功率谱密度
Table 1. Random vibration power spectral density
频率/Hz PSD/ (g2·Hz−1) 10 0.008 100 0.08 1 000 0.08 2 000 0.02 表 2 频域随机振动计算结果
Table 2. Calculation results of random vibration in frequency domain
单元号 z方向应力均方根值/MPa 特征频率/Hz 2 032 19.93 554.7/ 1114 2 100 13.61 554.7/ 1114 表 3 时域随机振动计算结果
Table 3. Calculation results of random vibration in time domain
时域信号时长/s 单元号 z方向应力均方根值/MPa 第1次 第2次 第3次 第4次 第5次 第6次 均值 标准差 0.2 2 032 21.73 15.82 19.82 22.18 14.69 22.27 19.42 3.07 2 100 14.86 10.82 13.55 15.17 10.13 15.24 13.30 2.07 1 2 032 22.96 18.09 17.28 20.57 17.46 21.02 19.56 2.10 2 100 15.72 12.36 11.81 14.07 11.93 14.37 13.38 1.45 表 4 时域分析与ABAQUS频域分析的应力均方根值对比
Table 4. Comparison of stress RMS values in time domain and ABAQUS frequency domain analysis
时域信号
时长/s单元号 时域应力
均方根值/MPaABAQUS频域
计算均方根值/MPa误差/% 0.2 2 032 19.42 19.93 −2.57 2 100 13.30 13.61 −2.31 1 2 032 19.56 19.93 −1.84 2 100 13.37 13.61 −1.71 表 5 管路频域与时域分析的应力均方根值对比
Table 5. Comparison of stress RMS values for pipeline in time domain and frequency domain analysis
单元号 时域计算S11
均方根值/MPa频域计算S11均方根值/MPa 模态阻尼比0.004 模态阻尼比0.006 模态阻尼比0.008 模态阻尼比0.01 模态阻尼比0.012 模态阻尼比0.014 216 478 4.37 8.53 6.97 6.04 5.41 4.94 4.57 215 740 7.13 11.28 9.2 7.96 7.12 6.5 6.01 217 038 2.59 6.08 4.97 4.31 3.86 3.53 3.26 表 6 3种构型的应力均方根值结果
Table 6. Stress RMS values of three configurations
单元号 S11应力均方根值/MPa 构型A 构型B 构型C 216 478 7.58 5.86 4.90 215 740 6.33 5.74 4.43 217 038 5.98 4.42 3.92 -
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