NURBS-based Optimization For Bolt Hole Geometry Design
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摘要:
基于非均匀有理B样条(NURBS)曲线,提出了一种螺栓孔设计优化方法,采用极点式双段NURBS曲线构建螺栓孔三维模型,以降低螺栓孔最大当量应力为优化目标,以极点坐标为设计优化变量,约束挡板最大径向位移、螺栓孔最大周向应力和螺栓压紧面积,建立了螺栓孔优化数学模型,采用强化学习差分进化(QLDE)算法开展优化,获得了螺栓孔的一种优化结构,计算表明:优化后的螺栓孔最大当量应力降低了19.0%,最大周向应力降低了12.7%,挡板最大径向位移减小了0.3%,螺栓压紧面积增大了0.5%,挡板低循环疲劳寿命提高了122%。试验验证了设计优化方法的有效性,低循环疲劳试验寿命显著提高,解决了挡板螺栓孔因低循环疲劳试验寿命低导致过早出现裂纹的失效问题。
Abstract:A bolt hole design optimization method based on Non-Uniform Rational B-Splines (NURBS) curves was proposed. The three-dimensional model of the bolt hole was constructed using a two-segment NURBS curve with pole-based control, with the optimization objective of minimizing the maximum equivalent stress. The pole coordinates served as design variables, while constraints included the maximum radial displacement of the baffle, maximum circumferential stress of the bolt hole, and bolt clamping area. A mathematical optimization model for the bolt hole was established, and the enhanced learning differential evolution (QLDE) algorithm was employed for optimization. The results showed that the optimized bolt hole achieved a 19.0% reduction in maximum equivalent stress, a 12.7% decrease in maximum circumferential stress, a 0.3% reduction in maximum radial displacement of the baffle, and a 0.5% increase in bolt clamping area, while the low-cycle fatigue life of the baffle improved by 122%. Experimental validation confirmed the effectiveness of the proposed method, with significantly enhanced low-cycle fatigue life. This addressed the failure issue of premature crack initiation in baffle bolt holes due to inadequate low-cycle fatigue life.
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Key words:
- Bolt holes /
- NURBS curves /
- design optimization /
- enhanced learning /
- differential evolution algorithm
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表 1 测试函数集
Table 1. Test functions
函数 范围 维度 $ {F}_{2} (\boldsymbol{x}) ={10}^{6}{x}_{1}^{2}+\displaystyle\sum\limits_{i=2}^{d}{x}_{i}^{2} $ $ {F}_{2} (\boldsymbol{x}) ={10}^{6}{x}_{1}^{2}+\displaystyle\sum\limits_{i=2}^{d}{x}_{i}^{2} $ 30 $ {F}_{2} (\boldsymbol{x}) ={10}^{6}{x}_{1}^{2}+\displaystyle\sum\limits_{i=2}^{d}{x}_{i}^{2} $ $ {F}_{3} (\boldsymbol{x}) =\displaystyle\sum\limits_{i=1}^{d}\left| {x}_{i}\right| +\prod\limits_{i=1}^{d}\left| {x}_{i}\right| $ 30 $ {F}_{3} (\boldsymbol{x}) =\displaystyle\sum\limits_{i=1}^{d}\left| {x}_{i}\right| +\prod\limits_{i=1}^{d}\left| {x}_{i}\right| $ $ {F}_{4} (\boldsymbol{x}) =\displaystyle\sum\limits_{i=1}^{d}{ ({{x}_{i}}+0.5) }^{2} $ 30 $ {F}_{4} (\boldsymbol{x}) =\displaystyle\sum\limits_{i=1}^{d}{ ({{x}_{i}}+0.5) }^{2} $ $ {F}_{5} (\boldsymbol{x}) ={\left| \displaystyle\sum\limits_{i=1}^{d}{x}_{i}^{2}-d\right| }^{1/4}+\left(0.5\displaystyle\sum\limits_{i=1}^{d}{x}_{i}^{2}+\displaystyle\sum\limits_{i=1}^{d}{x}_{i}\right)/d+0.5 $ 30 $ {F}_{5} (\boldsymbol{x}) ={\left| \displaystyle\sum\limits_{i=1}^{d}{x}_{i}^{2}-d\right| }^{1/4}+\left(0.5\displaystyle\sum\limits_{i=1}^{d}{x}_{i}^{2}+\displaystyle\sum\limits_{i=1}^{d}{x}_{i}\right)/d+0.5 $ $ {F}_{6} (\boldsymbol{x}) =\displaystyle\sum\limits_{i=1}^{d}\dfrac{x_{i}^{2}}{4\;000}-\prod\limits_{i=1}^{d}\cos \left(\dfrac{{x}_{i}}{\sqrt{i}}\right)+1 $ 30 $ {F}_{6} (\boldsymbol{x}) =\displaystyle\sum\limits_{i=1}^{d}\dfrac{x_{i}^{2}}{4\;000}-\prod\limits_{i=1}^{d}\cos \left(\dfrac{{x}_{i}}{\sqrt{i}}\right)+1 $ $ {F}_{7} (\boldsymbol{x}) =\displaystyle\sum\limits_{i=1}^{d}i{x}_{i}^{4}+{\mathrm{random}} (0,1) $ 30 $ {F}_{7} (\boldsymbol{x}) =\displaystyle\sum\limits_{i=1}^{d}i{x}_{i}^{4}+{\mathrm{random}} (0,1) $ $ {F}_{8} (\boldsymbol{x}) =4{x}_{1}^{2}-2.1{x}_{1}^{4}+\dfrac{1}{3}{x}_{1}^{6}+{x}_{1}{x}_{2}-4{x}_{2}^{2}+4{x}_{2}^{4} $ 30 $ {F}_{8} (\boldsymbol{x}) =4{x}_{1}^{2}-2.1{x}_{1}^{4}+\dfrac{1}{3}{x}_{1}^{6}+{x}_{1}{x}_{2}-4{x}_{2}^{2}+4{x}_{2}^{4} $ $ {F}_{9} (\boldsymbol{x}) =\displaystyle\sum\limits_{i=1}^{11}{\left[{{a}_{i}}-\dfrac{{x}_{1} ({b}_{i}^{2}+{b}_{i}{x}_{2}) }{{b}_{i}^{2}+{b}_{i}{x}_{3}+{x}_{4}}\right]}^{2} $ 2 $ {F}_{9} (\boldsymbol{x}) =\displaystyle\sum\limits_{i=1}^{11}{\left[{{a}_{i}}-\dfrac{{x}_{1} ({b}_{i}^{2}+{b}_{i}{x}_{2}) }{{b}_{i}^{2}+{b}_{i}{x}_{3}+{x}_{4}}\right]}^{2} $ $ X={[{{x}_{1}},{{x}_{2}},\cdots ,{{x}_{16}}]}^{{\mathrm{T}}},X\subset {R}^{16} $ 4 表 2 测试结果
Table 2. Test results
FUN QLDE DE PSO SA F1 平均值 4.69×10−5 9.38×10−1 1.66×10−1 6.43×10−4 平均误差 4.69×10−5 9.38×10−1 1.66×10−1 6.43×10−4 中位数 1.47×10−5 9.16×10−1 7.76×10−2 1.49×10−4 最好值 1.88×10−7 4.65×10−1 1.20×10−2 5.80×10−6 标准差 1.06×10−4 2.67×10−1 1.99×10−1 1.40×10−3 F2 平均值 2.53×10−4 2.17×100 4.00×102 1.44×10−3 平均误差 2.53×10−4 2.17×100 4.00×102 1.44×10−3 中位数 2.70×10−5 2.02×100 2.39×10−1 2.89×10−4 最好值 1.10×10−6 1.18×100 2.89×10−2 6.45×10−6 标准差 5.69×10−4 5.87×10−1 1.98×103 3.25×10−3 F3 平均值 1.15×10−3 2.04×10−1 1.28×100 2.70×10−3 平均误差 1.15×10−3 2.04×10−1 1.28×100 2.70×10−3 中位数 6.56×10−4 2.00×10−1 6.32×10−2 2.23×10−3 最好值 6.89×10−5 1.32×10−1 2.86×10−2 5.16×10−4 标准差 1.39×10−3 2.93×10−2 3.27×100 1.73×10−3 F4 平均值 1.14×10−4 8.96×10−1 1.48×10−1 6.98×10−4 平均误差 1.14×10−4 8.96×10−1 1.48×10−1 6.98×10−4 中位数 1.10×10−5 9.22×10−1 8.64×10−2 2.28×10−4 最好值 5.41×10−7 4.12×10−1 1.29×10−2 3.21×10−5 标准差 3.81×10−4 2.07×10−1 1.93×10−1 1.07×10−3 F5 平均值 5.55×10−1 6.72×10−1 6.86×10−1 5.26×10−1 平均误差 5.55×10−1 6.72×10−1 6.86×10−1 5.26×10−1 中位数 5.29×10−1 6.65×10−1 6.63×10−1 5.12×10−1 最好值 3.28×10−1 5.10×10−1 4.03×10−1 2.88×10−1 标准差 1.40×10−1 6.67×10−2 1.55×10−1 1.44×10−1 F6 平均值 1.27×10−2 8.48×10−1 2.22×10−1 6.98×10−2 平均误差 1.27×10−2 8.48×10−1 2.22×10−1 6.98×10−2 中位数 7.46×10−3 8.39×10−1 1.62×10−1 5.89×10−2 最好值 1.74×10−6 7.03×10−1 3.81×10−2 4.15×10−5 标准差 1.57×10−2 6.31×10−2 1.44×10−1 5.77×10−2 F7 平均值 2.79×10−2 9.84×10−2 5.36×10−2 2.28×10−1 平均误差 2.79×10−2 9.84×10−2 5.36×10−2 2.28×10−1 中位数 2.60×10−2 9.81×10−2 5.18×10−2 2.14×10−1 最好值 7.36×10−3 5.69×10−2 2.56×10−2 8.01×10−2 标准差 1.11×10−2 1.84×10−2 1.79×10−2 9.24×10−2 F8 平均值 −1.03×100 −1.03×100 −1.03×100 −1.03×100 平均误差 2.25×10−15 2.23×10−15 2.30×10−15 7.56×10−11 中位数 −1.03×100 −1.03×100 −1.03×100 −1.03×100 最好值 −1.03×100 −1.03×100 −1.03×100 −1.03×100 标准差 2.67×10−16 2.44×10−16 3.19×10−16 8.46×10−11 F9 平均值 3.62×10−4 7.82×10−4 1.44×10−3 1.39×10−2 平均误差 5.49×10−5 4.74×10−4 1.14×10−3 1.36×10−2 中位数 3.07×10−4 7.69×10−4 6.37×10−4 1.76×10−3 最好值 3.07×10−4 6.14×10−4 3.09×10−4 5.17×10−4 标准差 2.20×10−4 1.28×10−4 3.91×10−3 1.80×10−2 表 3 弗里德曼检验统计结果
Table 3. The Friedman test results
Friedman QLDE DE PSO SA F1 1 4 3 2 F2 1 3 4 2 F3 1 3 4 2 F4 1 4 3 2 F5 2 3 4 1 F6 1 4 3 2 F7 1 3 2 4 F8 2.5 2.5 2.5 2.5 F9 1 2 3 4 Average 1.3 3.2 3.2 2.4 Ranks 1 3.5 3.5 2 表 4 优化设计变量
Table 4. Optimization design variables
序号 参数名 初始值 下限 上限 1 x1/mm 55.5 53.0 57.0 2 x2/mm 56.3 54.0 59.0 3 x3/mm 57.7 56.0 58.0 4 x4/mm 59.0 57.0 61.0 5 x5/mm 60.0 58.0 63.0 6 x6/mm 32.5 32.0 33.8 7 x7/mm 53.2 51.0 56.0 8 x8/mm 52.0 50.0 54.0 9 x9/mm 51.0 49.0 53.0 10 y1/mm 5.6 5.0 6.0 11 y2/mm 5.0 4.7 5.5 12 y3/mm 4.7 4.5 5.2 13 y4/mm 4.2 4.0 4.5 14 y5/mm 5.9 5.2 6.3 15 y6/mm 5.8 5.5 6.4 16 y7/mm 4.5 4.0 5.0 表 5 优化结果计算值
Table 5. Calculated values of the optimization result
参数 优化前 优化后 变化率/% 螺栓压紧面积/mm2 68.001 68.312 +0.5 螺栓孔最大当量应力/MPa 1754.2 1420.1 −19.0 螺栓孔最大主应力/MPa 1800.4 1427.4 −20.7 螺栓孔最大周向应力/MPa 1615.7 1410.9 −12.7 挡板最大径向位移/mm 0.6968 0.6950 −0.3 低循环疲劳寿命/次 6204 13789 +122 表 6 低循环疲劳试验阶段
Table 6. Low-cycle fatigue life test phase
试验阶段 试验次数 第1阶段 0~ 4000 第2阶段 4000 ~8000 第3阶段 8000 ~12000 表 7 优化前后低循环疲劳寿命次数
Table 7. Low-cycle fatigue life cycles before and after optimization
参数 优化前 优化后 变化率 低循环疲劳寿命/次 < 8000 > 12000 >+50% -
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