共查询到18条相似文献,搜索用时 125 毫秒
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以某航空发动机整体叶盘简化模型为研究对象,对叶片表面涂覆NiCrAlY硬涂层,建立硬涂层整体叶盘有限元模型。针对不同工况下仅考虑离心力影响和同时考虑科氏力和离心力影响的2种情况,进行模态分析,研究离心力和科氏力对不同转速下硬涂层整体叶盘模态特性的影响,并讨论硬涂层对整体叶盘系统固有特性的影响;最后,根据计算得到的固有频率,得到2种不同载荷下的坎贝尔图,求得硬涂层整体叶盘发生共振时的危险转速。结果表明:转速越大,固有频率值升高,科氏力对频率特性影响越大;硬涂层对整体叶盘结构的频率影响较小,硬涂层削弱了科氏力的影响;对于高速旋转的整体叶盘系统,科氏力影响显著,工程计算时不可忽略。 相似文献
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针对航空发动机涡轮叶盘运行中产生的疲劳裂纹改变振动特性的问题,基于有限元模态分析理论对其进行研究。建立不同裂纹长度、裂纹分布位置的整体叶盘有限元模型,分别分析动静态下固有频率的变化;分析裂纹对整体叶盘频率转向的影响;最后,通过分析含裂纹叶片在激励作用下的响应,得出其响应幅值和振动方向的变化。结果表明:裂纹会降低整体叶盘固有频率,且对低阶频率影响较大;裂纹会影响整体叶盘振型,出现振动局部化现象;裂纹的出现影响整体叶盘频率转向现象的发生;整体叶盘中含裂纹叶片的响应峰值随着裂纹长度的增加而逐渐增大,且裂纹叶片会出现大范围振动反向现象。 相似文献
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《组合机床与自动化加工技术》2019,(3)
为提高数控车床的动态特性,改善车床的加工精度、稳定性和抗振性,利用基于PolyMax模态参数识别方法对TCK46A数控车床进行模态实验和在DHDAS动态信号采集分析系统中进行动态特性分析,得到了该车床准确的前6阶固有频率、阻尼比和模态振型。根据模态实验结果分析得出该数控车床在1阶固有频率低于最高激励频率58.33Hz时,车床可能发生共振,其薄弱环节为主轴箱和床身,并提出了相应的改进设计方法和减振措施,以期为该车床的动态特性设计与研究提供参考。 相似文献
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针对快速锻造液压机的有限元建模,本文将以往研究中的活动横梁与机架整体建模,改进为活动横梁与机架采用节点耦合和弹簧连接的方式建模,较好地模拟了液压机的工作连接情况。通过对80MN快速锻造液压机进行有限元模态分析计算,获得了有限元模态频率和模态振型,模态频率分析表明本液压机的最小固有频率为3.8486Hz,大于其工作频率1.25Hz,液压机不会发生共振。模态振型分析表明第三阶振型的振幅相对其它阶大出21.9%以上,下横梁振动对液压机工作精度的影响较大。 相似文献
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整体叶盘在复杂多变载荷的作用下易出现振动损伤和使用寿命缩短等问题。针对此问题,以整体叶盘简化模型为对象,对叶片的压力面涂敷NiCrAlY硬涂层并建立叶盘的流场模型;在Fluent软件中采用流固耦合方法分别对无硬涂层、有硬涂层整体叶盘进行叶盘表面气动载荷的模拟;最后,采用预应力模态分析法对无硬涂层、有硬涂层整体叶盘在气动载荷、离心载荷、气动和离心载荷共同作用下的振动响应、等效应力的分布进行求解,以及绘制叶盘的坎贝尔图。依据以上求解结果,对比研究了硬涂层和3种载荷方式对整体叶盘振动特性的影响程度。结果表明:硬涂层对整体叶盘的振动特性影响较小;相比离心载荷,离心和气动载荷共同作用时对整体叶盘振动特性影响更明显;硬涂层会降低整体叶盘的共振点数。 相似文献
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为了研究复杂载荷对整体叶盘振动特性的影响,基于热流固耦合方法对热障涂层整体叶盘振动特性进行研究。简化整体叶盘模型,对叶片表面涂敷热障涂层并建立整体叶盘的流场模型;在Fluent中采用热流固耦合方法对整体叶盘的表面进行气动载荷和温度载荷的模拟;最后,采用预应力模态分析法分别对不同工况下整体叶盘的振动特性进行分析。结果表明:考虑离心载荷对整体叶盘的固有频率影响最大,温度的影响最小;对比不同工况下,考虑温度载荷对整体叶盘的共振点个数无影响,气动载荷增加整体叶盘的共振点个数。 相似文献
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为了获得全面的振动特性参数,应用LMS.Test.Lab振动测试系统对典型的快走丝线切割机床DK7735进行试验。分析试验结果可以看出:DK7735丝架在266~288 Hz、347~397 Hz、875~943 Hz频率段内的模态振型对加工质量影响最大,因此应避免机床在运行过程中产生的振动激励落在该范围内;机床下臂前段的阻尼比为0.30左右,结构抗振能力较差,应对此处进行结构优化;DK7735的第1、2阶固有频率集中在160、285 Hz附近,从第3阶开始固有频率的分布就比较分散。 相似文献
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针对数控蜗杆砂轮磨齿机磨削过程中具有简谐振动的特点,建立其主轴系统的三维有限元模型。利用有限元分析软件ANSYS进行模态分析和谐响应分析。通过模态分析求解获得了主轴系统的固有频率和振型,并研究了角接触球轴承支承刚度对其固有频率的影响;通过谐响应分析获得了主轴系统的变形—频率响应曲线,最后通过计算临界转速来验证主轴系统是否发生共振。研究结果表明:增大角接触球轴承的支承刚度有利于提高主轴系统的固有频率。磨削激振力的频率在600Hz附近时,变形—频率响应曲线出现了最大的峰值响应为6.56μm。为了避免共振,主轴系统的工作转速应尽量避开一阶临界转速。 相似文献
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Sun-Min Kim Jae-Hoon Ha Sung-Ho Jeong Sun-Kyu Lee 《International Journal of Machine Tools and Manufacture》2001,41(12):1251
A numerical model of a grinding wheel spindle was presented to analyze the dynamic behavior of the wheel spindle with respect to joint conditions. Each joint condition of the wheel-spindle assembly was modeled to examine the dynamic behavior change due to disk mode vibration and joint conditions such as the bolt tightening forces between flange and wheel, and the taper tightening force between shaft and flange contact surface. The effects of bolt and taper coupling joint conditions on the dynamic characteristics, natural frequency and damping ratio of vibration modes, were numerically investigated using this model. Experiments were performed to measure modal parameters and compared with the numerical results. The numerical results obtained from the model agreed well, within 5%, with the experimental results. It was found that joint conditions, such as bolt tightening force and taper tightening force, have significant influence on the dynamic characteristics; the maximum natural frequency change was about 60%. It was also shown that the disk mode vibration of the wheel greatly affects the vibration mode of a wheel-spindle assembly. 相似文献
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《Journal of Materials Processing Technology》2000,97(1-3):114-119
In this paper, the effects of the multi-layer hard surface coating of cutting tools on the cutting forces in steel turning are presented and discussed, based on an experimental investigation with different commercially available carbide inserts and tool geometries over a range of cutting conditions. The cutting forces when turning with surface coated carbide inserts are assessed and compared qualitatively and quantitatively with those for uncoated tools. It is shown that hard surface coatings reduce the cutting forces, although the reduction is marginal under lighter cutting conditions. The cutting force characteristics for surface coated tools are also discussed and shown to have similar trends to those of uncoated tools. 相似文献
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A Piezo Tool Actuator for Precision Turning of Hardened Shafts 总被引:1,自引:0,他引:1
Y. AltintasA. Woronko 《CIRP Annals》2002,51(1):303-306
A piezo actuator based fast tool servo is presented for precision turning of cylindrical shafts. The monolithic actuator housing transmits motion to the tool assembly using solid flexures. The actuator has a stroke of 36 μm, 3200 Hz natural frequency, and 370 N/μm stiffness. Two sets of additional piezo actuators are placed in the transverse direction to clamp the tool for increased stiffness during hard turning operations. A sliding mode controller rejects cutting forces and compensates the piezo stack nonlinearities. The tool position is controlled to within 10 nm during finish hard turning on a conventional CNC lathe. 相似文献
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针对机器人刚性差造成的磨削振动工作模态参数难以预测的问题,建立工艺参数与系统固有频率的关系模型。在简化机器人磨削系统的基础上,提出磨削接触刚度的测量方法。运用摄动法求解振动矩阵方程,将工艺参数与工作模态以磨削接触刚度为纽带联系起来。应用机器人-砂带机磨削平台进行试验验证,改变不同工艺参数测量工作模态,与计算值进行对比,证明数学模型的准确性,并进一步得到不同磨削工艺参数对接触刚度、系统固有频率的影响规律。研究结果为避免或抑制机器人-砂带机磨削系统产生磨削振动以及磨削工艺参数优化提供了参考。 相似文献
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Sub-micrometer cobalt flakes were successively fabricated by hydrazine reduction in aqueous solution, the flakes were coated with silica layers by the hydrolysis method. Their microwave and static magnetic properties were investigated. The silica coated cobalt flakes are characterized with high resonance frequency at 4 GHz, and the real part of permeability μ′ were greatly improved when frequency was lower than resonance frequency. The improvement is ascribed to the suppression of eddy current loss after silica coating. The spectra of complex permeability were fitted with the Landau-Lifshitz-Gilbert equation and the resonance mode is proved to be the natural resonance mode. 相似文献
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以双缝普通电弧焊矩形薄板为典型试件,系统研究了用不同振型对应频率激振时焊接件残余应力降低的幅度。结果表明:试件振型对振动时效激振频率的选择有影响,采用固有振型对应频率激振,试件焊接残余应力降低效果比采用非固有振型效果明显;对于矩形板状焊接件,沿着焊缝方向的低阶固有弯曲振型对应的焊接残余应力消除率最大,一般优先选用具有均匀位移变形的简单振型对应频率对试件进行激振。 相似文献