低温风洞电动推杆热防护结构非线性屈曲分析
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摘要
为避免电动推杆元件在低温风洞中工作时受到低温损伤而无法正常工作,设计了使其能够在低温环境下正常工作的热防护结构。基于ANSYS软件建立了热防护结构有限元模型并进行线性屈曲分析,得到了相应屈曲模态。考虑材料非线性,以线性屈曲模态作为结构初始几何缺陷形式,使用Newton-Raphson算法控制载荷加载对热防护结构进行了非线性屈曲分析。结果表明:一阶线性屈曲临界压力为1.651MPa,以其变形量的0.1倍作为初始几何缺陷得到非线性屈曲临界压力为1.544MPa,考虑安全系数(m=3)后许用外压为0.515MPa,高于低温风洞最大工作压力0.35MPa。热防护结构非线性屈曲临界压力随初始几何缺陷的增加而降低,当初始几何缺陷大于一阶线性屈曲模态变形量的约1.4倍时,许用外压低于0.35MPa,结构有可能发生失稳。不同初始几何缺陷形式对热防护结构的临界压力几乎无影响,但结构最终破坏形式不同。
In order to avoid the linear actuator be able not to work normally in cryogenic wind tunnel because of cryoinjury,a thermal protection structure was designed. The finite element model of the thermal protection structure was established based on ANSYS software,while corresponding buckling mode was also obtained through linear buckling analysis. Considering nonlinearity of the material and using the linear buckling mode as the form of initial geometrical imperfections,the nonlinear buckling analysis was carried out by using New-Raphson algorithm to control the loading of the load. The following findings were obtained based on the above analysis. The critical pressure of first linear buckling is 1. 651 MPa. The critical pressure of nonlinear buckling analysis,which sets 0. 1 times of its deformation as initial geometrical imperfection,is 1. 544 MPa. Permitted external pressure is 0.515 MPa after considering the safety factor( m = 3),which is higher than the extreme pressure of cryogenic wind tunnel( 0.35 MPa). The critical pressure of nonlinear buckling decreases with the increase of the initial geometrical imperfections. When the initial geometrical imperfections are greater than about 1. 4 times of the first order linear buckling mode deformation,permitted external pressure is lower than 0. 35 MPa,the structure may be unstable. Different forms of initial geometrical imperfection have little influence to critical pressure of the thermal protection structure,but the final destruction forms of the structure are different.
In order to avoid the linear actuator be able not to work normally in cryogenic wind tunnel because of cryoinjury,a thermal protection structure was designed. The finite element model of the thermal protection structure was established based on ANSYS software,while corresponding buckling mode was also obtained through linear buckling analysis. Considering nonlinearity of the material and using the linear buckling mode as the form of initial geometrical imperfections,the nonlinear buckling analysis was carried out by using New-Raphson algorithm to control the loading of the load. The following findings were obtained based on the above analysis. The critical pressure of first linear buckling is 1. 651 MPa. The critical pressure of nonlinear buckling analysis,which sets 0. 1 times of its deformation as initial geometrical imperfection,is 1. 544 MPa. Permitted external pressure is 0.515 MPa after considering the safety factor( m = 3),which is higher than the extreme pressure of cryogenic wind tunnel( 0.35 MPa). The critical pressure of nonlinear buckling decreases with the increase of the initial geometrical imperfections. When the initial geometrical imperfections are greater than about 1. 4 times of the first order linear buckling mode deformation,permitted external pressure is lower than 0. 35 MPa,the structure may be unstable. Different forms of initial geometrical imperfection have little influence to critical pressure of the thermal protection structure,but the final destruction forms of the structure are different.
引文
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[2]游立新,程克明.低温风洞应用与发展探讨[J].中国空间科学技术,1995,15(6):35-40.
[3]计光华.液氮在低温风洞中的应用[J].低温与特气,1989(4):31-35.
[4]Green J,Quest J.A short history of the European Transonic Wind Tunnel ETW[J].Progress in Aerospace Sciences,2011,47(5):319–368.
[5]初艳玲.考虑初始缺陷的结构非线性屈曲分析与应用[J].中国造船,2010,51(3):119-127.
[6]康习锋,张宏.基于ANSYS的管道屈曲临界载荷分析[J].油气储运,2017,36(3):262-266.
[7]丁昌,汪荣顺.带缺口加强圈的圆柱壳屈曲特性分析[J].低温与超导,2009,37(2):44-47.
[8]杨春光,肖尤明,李志伟,等.聚氨酯泡沫液氮温度下热导率的测量[J].低温与超导,2004,32(2):25-28.
[9]臧少锋,钱才富.超大型真空容器非线性稳定分析[J].北京化工大学学报(自然科学版),2009,36(5):88-91.
[10]方贤骏.CARDC 0.1米低温风洞的工程设计和运行特性[J].实验流体力学,1993(1):40-49.
[11]Pellegrino C,Maiorana E,Modena C.Linear and non-linear behavior of steel plates with circular and rectangular holes under shear loading[J].Thin-Walled Structures,2009,47(6):607-616.
[12]周炬,苏金英.ANSYS Workbench有限元分析实例详解(静力学)[M].北京:人民邮电出版社,2017.
[13]付敏,林松,陈亮,等.纤维缠绕复合材料气瓶内衬的屈曲分析[J].材料科学与工艺,2015,23(2):86-90.
[14]万春华,段世慧,吴存利,等.初始几何缺陷对加筋结构后屈曲分析的影响[J].航空计算技术,2017(1):90-93.
[15]寿比南.GB 150-2011《压力容器》标准释义[M].北京:新华出版社,2012.
[16]王珂晟,刘国强,朱晓莹.含初始缺陷的加强复合材料圆柱壳的非线性屈曲分析[J].机械设计与制造,2004(2):63-65.