廖愛華, 黃 旭, 方 宇
(上海工程技術大學城市軌道交通學院 上海,201620)
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基于剛柔耦合的軌道車輛轉向架構架疲勞分析*
廖愛華, 黃 旭, 方 宇
(上海工程技術大學城市軌道交通學院 上海,201620)
對某型地鐵車輛轉向架構架在運行使用過程中局部區(qū)域出現裂紋的問題,首先,基于固定界面模態(tài)綜合法,通過構架主自由度縮減得到了該型構架柔性體模型,從而建立該型地鐵車輛剛柔耦合多體動力學模型;然后,結合一種基于柔性體計算結構動應力的方法,探討該型構架的動應力響應,得到該型構架的振動特性;最后,采用準靜態(tài)應力疊加法對構架電機吊座結構進行了疲勞壽命預測。仿真結果與該型構架實際出現疲勞破壞的位置吻合,從而驗證了基于剛柔耦合模型對構架進行疲勞分析方法的正確性。結果表明,利用這種方法可以在構架前期開發(fā)階段為其疲勞壽命預測提供理論依據。
轉向架構架; 多體動力學; 剛柔耦合; 疲勞壽命
轉向架構架作為地鐵車輛的主要承載部件,其承受著頻繁的隨機載荷,所受工況比較惡劣。以某型地鐵車輛轉向架構架為例,該型車輛轉向架構架在運行使用過程中構架多次出現裂紋現象,構架的使用壽命遠遠小于設計壽命[1],該現象嚴重影響了地鐵車輛的運行安全性。因此,對影響地鐵車輛運行安全的關鍵部件轉向架構架進行疲勞分析以及疲勞壽命預測顯得尤為重要。
國內外學者在結構的疲勞分析這個領域做了大量的研究,這些方法同樣可以應用于轉向架構架的分析和研究中。目前國內外對于結構的疲勞分析主要從實驗[2]和仿真[3-6]兩個角度作為切入點。線路實測動應力實驗及疲勞實驗比較昂貴,且線路實測動應力實驗受線路、氣候條件的影響較大。而仿真主要依靠多體動力學仿真聯合有限元分析的準靜態(tài)疊加法來實現結構動應力的計算,該方法適用于結構固有頻率運離外部載荷頻率的情況。由于地鐵車輛轉向架構架所承受的是復雜的耦合動載荷場,結構架局部動剛度較小,很可能會出現局部共振現象。此時除了外部載荷激勵,還需考慮局部共振造成的自振激勵。因此,本研究以構架結構自身振動特性作為出發(fā)點,建立構架柔性體模型,并結合地鐵車輛剛柔耦合多體動力學仿真得到構架結構的動應力響應,從而得到構架的振動特性,并依據此對該型構架進行疲勞分析,進而得到其疲勞破壞機理,最后基于準靜態(tài)應力疊加法預測構架電機吊座的疲勞壽命。
1.1 柔體動力學理論
柔性體理論主要基于固定界面模態(tài)綜合法[7],其基本思想是賦予柔性體一個模態(tài)集,采用模態(tài)法展開,用模態(tài)向量和模態(tài)坐標的線性組合表示物體的彈性位移,通過計算每一時刻物體的彈性位移來表示其變形,令柔性部件r的界面固定,并建立模態(tài)矩陣,其中模態(tài)矩陣可表示為
(1)
其中:φIN為主模態(tài)矩陣;φIC為約束模態(tài)矩陣。
主模態(tài)qN是界面自由度固定時所對應的固有模態(tài),其與內部自由度一一對應;而約束模態(tài)qC是指依次釋放每一邊界自由度,使其產生單位位移而形成的靜位移分布所構成的靜態(tài)模態(tài),則可得
(2)
其中:I和0分別為單位矩陣和零矩陣;s為位移矩陣。
通過轉換,得到柔性體的運動方程
(3)
由于模態(tài)矩陣中,存在慣性耦合,需對其進行正則化轉換,消除剛體模態(tài),重新代入柔性多體系統(tǒng)中,采用拉格朗日建立整個系統(tǒng)的方程,從而得到系統(tǒng)的解。
1.2 建立柔性構架
該型轉向架構架主體采用牌號為DIN-ST52結構鋼,材料的彈性模量為2.1×105MPa,泊松比為0.29,密度為7.8×103kg/m3,極限強度標準值為510MPa,屈服強度標準值為355MPa。選取SHELL63,SOLID45以及MASS三類單元來建立構架的有限元模型,依據模態(tài)綜合法,選取若干固定交互點進行主自由度縮減,最終得到柔性構架。
傳統(tǒng)的剛體動力學模型忽略了結構內部的相對位移,若結構在運動過程中發(fā)生了共振,此時如若按照傳統(tǒng)結構靜強度計算方法,計算得到的應力會小于實際結構應力。所以,從結構動力學的角度出發(fā),以結構模態(tài)位移為基礎,通過模態(tài)應力恢復計算結構應力。
柔性體中的某一節(jié)點的模態(tài)位移X可以由若干階模態(tài)振型相互疊加得到
(4)
其中:hj為第j階模態(tài)頻率;wj為第j階頻率對應的模態(tài)位移。
根據模態(tài)綜合法,模態(tài)矩陣H是由靜模態(tài)與特征模態(tài)組合而成,靜模態(tài)的數量等于約束特征點的自由度的總和,特征模態(tài)是通過求解式(5)得到
(5)
其中:M為質量矩陣;C為剛度矩陣;λ為特征值;y為特征模態(tài)。
(6)
(7)
通過求解式(8,9)進行模態(tài)矩陣的正則化,得到柔性體的模態(tài)信息
(8)
(9)
依據有限元離散理論可得
(10)
(11)
通過代入柔性體某一節(jié)點i的模態(tài)位移可推出柔性體中某節(jié)點i的應力與應變。將式(4)分別帶入式(10,11)則可推出式(12,13)
(12)
(13)
由此可知,只要獲取柔性體中每個節(jié)點的模態(tài)位移,則可以得到柔性體中每一個節(jié)點的動應力響應。
利用1.2節(jié)得到的柔性構架,根據該型地鐵車輛真實動力學參數以及結構參數,最終建立該型地鐵車輛的剛柔耦合多體動力學模型如圖1所示。在建模過程中對柔性構架所受初始載荷進行預平衡,則在動力學仿真過程中柔性構架所承受的隨機載荷也就模擬了車輛運行過程中構架的實際受力狀態(tài)。
圖1 地鐵車輛剛柔耦合多體動力學模型Fig.1 The rigid-flexible coupling multibody dynamics model of metro vehicle
以該型地鐵車輛在滿載AW2下時速72 km/h作為仿真的邊界條件,并以美國五級譜作為軌道激勵進行仿真,仿真時間設為80 s。
3.1 構架整體結構動應力響應分析
構架屬于準對稱結構形式,在不影響仿真計算的精度并能縮短計算時間的情況下,選取構架的一半區(qū)域作為分析對象。結合實際情況,由于安裝座結構均為整體鑄件結構,運營過程無任何裂紋情況發(fā)生,未出現疲勞破壞現象,所以計算結構動應力響應時沒有考慮在內,構架結構應力分布云圖如圖2所示。
構架最大應力節(jié)點號為47 292,輸出該節(jié)點的動應力歷程如圖3所示。
圖2 構架結構應力分布云圖Fig.2 The structure stress distribution of frame
圖3 節(jié)點47 292動應力Fig.3 The dynamic stress of node 47 292
圖4 構架應力幅值分布云圖Fig.4 The stress amplitude distribution of frame
圖5 構架裂紋位置Fig.5 The crack area of frame
節(jié)點47 292處的應力最大值為142.3 MPa,小于該型構架母材的許用應力178 MPa,符合構架的強度要求。由于結構的破壞主要是由結構動應力的幅值引起的,應力幅值擾動是引起結構破壞的主要原因。應力幅值過大的區(qū)域主要集中在電機吊座區(qū)域、齒輪箱吊座區(qū)域、橫梁和側梁連接區(qū)域。該型構架電機吊座區(qū)域的應力幅值分布云圖如圖4所示,仿真結果與構架實際出現疲勞破壞的位置(圖5)大體一致。
由于電機吊座工字型加強板(圖4)整體所受應力幅值較大,從而導致該處(圖5)加強板底部焊縫區(qū)域經常出現裂紋。針對此處焊縫區(qū)域,取其中應力幅值最大的一個節(jié)點(337 853)進行分析,該節(jié)點的動應力如圖6所示。
圖6 焊縫節(jié)點動應力Fig.6 The dynamic stress of node in weld bead
由圖6得知,焊縫處節(jié)點最大應力值為27.6 MPa,電機吊座加強板采用的是對接焊縫,且焊縫焊接材料為脆性材料。依據BS7608焊接疲勞標準,該處的焊縫區(qū)域的疲勞強度極限值要遠遠小于母材,這也是該處經常出現裂紋的主要原因。
3.2 構架各局部區(qū)域疲勞分析
以該型地鐵車輛在滿載AW2下時速80 km/h作為仿真的邊界條件,并以美國五級譜作為軌道激勵進行仿真,仿真時間設為80 s。分別對上述易疲勞區(qū)域進行疲勞分析,得到各區(qū)域的應力幅值分布云圖,并輸出各個區(qū)域的應力幅值最大節(jié)點的動應力圖。
1) 電機吊座區(qū)域疲勞分析結果如圖7,8所示。
圖7 電機吊座區(qū)域應力幅值分布云圖Fig.7 The stress amplitude distribution of motor suspension
圖8 80 km/h工況下節(jié)點動應力Fig.8 The dynamic stress of node under the working condition of 80 km/h
2) 齒輪箱吊座區(qū)域疲勞分析結果見圖9,10。
圖9 齒輪箱吊座應力幅值分布云圖Fig.9 The stress amplitude distribution of gear suspension
圖10 80 km/h工況下節(jié)點動應力Fig.10 The dynamic stress of node under the working condition of 80 km/h
3) 橫梁-側梁連接區(qū)域疲勞分析結果如圖11,12所示。
圖11 橫梁-側梁連接區(qū)域應力幅值分布云圖Fig.11 The stress amplitude distribution of the connection area between beam and side beam
圖12 80 km/h工況下節(jié)點動應力Fig.12 The dynamic stress of node under the working condition of 80 km/h
由圖7,圖9,圖11得知,電機吊座區(qū)域的最大應力幅值為43 MPa,相對于齒輪箱吊座區(qū)域和橫梁-側梁連接區(qū)域的最大應力幅值較大。由圖8、圖10、圖12可看出,電機吊座區(qū)域的結構動應力比齒輪箱吊座區(qū)域以及橫梁-側梁連接區(qū)域整體要大,這也解釋了該型構架在運行過程中電機吊座出現裂紋頻率較高的原因。
準靜態(tài)應力疊加法的主要思想是計算任一時刻相同結構位置和相同作用方向的單位靜態(tài)載荷所引起的彈性應力應變狀態(tài),然后將其與之對應的載荷譜疊加得到結構的動應力,結合材料S-N曲線,并修正平均應力,最后依據線性損傷累計原則對結構開展疲勞壽命預測。
4.1 單位載荷作用下的電機吊座結構慣性釋放有限元分析
慣性釋放的原理[8]是通過構造一個自平衡力系來模擬約束不足時的結構靜態(tài)響應。在電機吊座質心處施加沿x,y,z正方向單位力以及繞x,y,z3個坐標軸順時針的單位轉矩。限于篇幅,以單位垂向載荷作用下為例,電機吊座應力、應變分布云圖如圖13所示。
從圖13可以看出,應力較大的部位主要集中在電機吊座四塊工字型加強板區(qū)域,工字型加強版區(qū)域整體應力較大。
圖13 z方向單位載荷作用下的應力分布云圖Fig.13 The stress distribution under unit load along z direction
4.2 電機吊座邊界載荷的計算
依據建立的地鐵車輛剛柔耦合多體動力學模型,根據該型車輛實際運行線路參數選取一段長為10 km的線路。以該型地鐵車輛在滿載AW2工況下時速72 km/h速度運行,采用美國五級譜作為激勵譜,獲取電機吊座的邊界載荷Fx,Fy,Fz,Mx,My,Mz,其中電機吊座垂向力如圖14所示。
圖14 電機吊座垂向力FZFig.14 The vertical force FZ of motor suspension
4.3 電機吊座疲勞壽命預測結果
依據上述得到電機吊座有限元分析結果以及動力學仿真獲得的電機吊座邊界載荷,利用nCode仿真得到電機吊座結構疲勞壽命分布云圖,如圖15所示。
圖15 電機吊座結構疲勞壽命分布云圖Fig.15 The fatigue life distribution of motor suspension
由圖15得知,電機吊座安裝座整體鑄件結構為無限壽命,疲勞壽命最短的位置出現在電機吊座工字型加強板與電機安裝座的焊縫連接處,仿真獲得的電機吊座疲勞壽命較短位置與實際電機吊座發(fā)生疲勞破壞的位置吻合的很好。仿真計算得到的電機吊座結構疲勞壽命為1.53×105次循環(huán),每次循環(huán)10km,則可計算得到電機吊座節(jié)點最短壽命為153萬km。根據地鐵檢修部門提供的數據,電機吊座處出現裂紋平均里程為139萬km,兩者誤差為10%。
1) 該型構架結構應力最大值為142.3MPa,小于該型構架母材的許用應力178MPa,符合構架的強度要求。應力幅值擾動是引起結構破壞的主要原因,該型構架應力幅值過大的區(qū)域主要集中在電機吊座區(qū)域、齒輪箱吊座區(qū)域、橫梁-側梁連接區(qū)域。仿真結果與該型構架實際出現疲勞破壞的位置吻合,從而驗證了基于剛柔耦合模型對結構進行疲勞分析方法的正確性。
2) 采用準靜態(tài)應力疊加法對構架易疲勞區(qū)域-電機吊座結構進行疲勞壽命預測,仿真得到電機吊座節(jié)點最短壽命為153萬km。計算結果符合地鐵檢修部門提供的數據:電機吊座該處出現裂紋平均里程為139萬km。仿真結果與實際數據誤差為10%,可知仿真可信性及正確度較高。
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Control of Hysteresis Nonlinearity for Scanning Stage in Scanning Tunneling Microscope
JIHongli1,SUNHongjun1,QIUJinhao1,CHENYuansheng2,ZHUKongjun1
(1.State Key Laboratory of Mechanics and Control of Mechanical Structures,Nanjing University of Aeronautics and Astronautics Nanjing ,210016, China) (2.School of Energy and Power Engineering, Nanjing University of Science and Technology Nanjing, 210094, China)
Abstract Piezoelectric actuators have been widely applied in scanning tunneling microscope (STM). A controller combining inverse hysteresis model and PID control law was designed for the STM to compensate for the hysteresis nonlinearity of piezoelectric actuators and to improve the scanning accuracy. For the purpose of comparing the proposed controller with classical displacement feedback control law, experimental system was built in this investigation. The relative measuring error of grating period and width of grating line were 4.41% and 2.65% using the classic displacement feedback control method respectively. And they were reduced to 1.26% and 0.27% in proposed method. Experimental results indicate that the error caused by hysteresis nonlinearity has been well compensated, and the scanning accuracy is improved with the help of such controller.
Keywords scanning tunneling microscope; piezoelectric actuator; hysteresis control; scanning control
Compressed Sensing and Reconstruction Method Based on Sparsity in Phase Space
WENGuangrui,LUANRiwei,RENYanhui,MAZaichao
(Mechanical Engineering College of Xi′an Jiaotong University Xi′an, 710049, China)
Abstract Aiming at the poor frequency sparsity of the vibration signal from a rotating machinery, which is interfered with strong noise and represented by the conventional FFT, a compressed sensing based on the sparsity in phase space is proposed to realize the signal reconstruction with orthogonal matching pursuit (OMP). First, the frequency sparsity is improved by reconstructing the original signal in a phase space and then principal components analysis (PCA) is implemented to extract the features in the constructed space; second, a random gauss matrix and OMP are adopted respectively to compress and reconstruct the improved signal. Analysis of the simulation signal and the misalignment signal of a rotor system suggest that the proposed method can enhance the frequency sparsity of the investigated signal. Moreover, the efficient compression and the accurate reconstruction of the investigated signal have also been realized.
Keywords compressed sensing; phase space reconstruction; principal component analysis; orthogonal matching pursuit
Research on the Identification in of Waveness Error in Diamond Fly Cutting for KDP Crystals
YANGHong,WANGBaorui,JIfang,LIUYouhai,XIAHuan,CHENDongsheng
(Institute of Machinery Manufacturing Technology, CAEP Mianyang, 621900, China)
Abstract Frequency identification is the prerequisite for eliminating or reducing ripple wave error in ultra-precision diamond fly cutting on KDP crystals. To address this problem, a method for the identification of the ripple waves error of diamond fly cutting trajectory based on spatial frequency transformation was proposed. The method calculated the spatial frequencies of ripple wave error according to the fly cutting profile of the arc-shaped trajectories. Then, the accurate separation of the characteristic frequencies was realized when the frequencies were transformed in time . The contrast between the characteristic frequencies of wave error with the cutting vibration frequencies and the natural frequencies of air spindle showed that the self-excited vibration at the natural frequencies of air spindle under intermittent cutting forces and the forced vibration from the motor was the primary reasons for ripple wave erro. Base on the above conclusion, by optimizing the structure and drive of the air spindle, the RMS value at PSD1 band (2.5~33 mm) of KDP crystal fly cutting surface reduced from 53 nm to 12 nm.
Keywords diamond fly cutting; ripple wave error; spatial frequency; KDP crystal
Analysis on Process of Vortex-induced Vibration of Risers Based on FBG Sensing Technology
LIPeng1,2,WANGLai1,2,GUOHaiyan3,WANGFei1,2,ZHANGYongbo4
(1.College of Architecture and Civil Engineering,Shandong University of Science and Technology Qingdao, 266590,China)(2.Shandong Provincial Key Laboratory of Civil Engineering Disaster Prevention and Mitigation,Shandong University of Science and Technology Qingdao, 266590, China)(3.College of Engineering, Ocean University of China Qingdao, 266100, China)(4.National Oceanographic Center of Qingdao Qingdao, 266071, China)
Abstract To further investigate the applicability of fiber Bragg grating (FBG)sensors sensing technology for testing of vortex-induced vibration(VIV) of deep-sea risers, this paper describes laboratory tests of VIV of a model deep-sea riser in a uniform current, which were carried out in a wind-wave-current flume. The riser model, 1.5 m long and with a slenderness ratio of 83.33, was tested in conditions in which the upper 0.75 m was in air, while the lower 0.75 m was exposed to a uniform current. FBG sensors were used for data acquisition and dynamic strain sensors were used for comparison. By changing the external flow velocity, the difference of the VIV process of the riser attained by two different sensors was analyzed and the vibration performance of the riser such as dominant frequency, amplitude and modal response based on frequency analysis and modal theory were researched implemented. The results indicate that requirement of FBG technology for testing of VIV of deep-sea risers can be wonderful satisfied. The vibration performance of the riser is accurately demonstrated. Modal characteristics and VIV process of the riser accompanying external flow velocity process are clearly reflected. The instantaneity and self-excitation of generation of the ‘lock-in’ region is found clearly.
Keywords FBG sensors; uniform current; marine riser; vortex-induced vibration(VIV); process analysis
Roller Bearing Fault Diagnosis Method Based on LMD-CM-PCA
FUYunxiao1,2,JIALimin1,3,QINYong1,3,YANGJie1
(1.State Key Laboratory of Rail Traffic Control and Safety, Beijing Jiaotong University Beijing, 100044, China)(2.School of Electric Engineering, Beijing Jiaotong University Beijing, 100044, China)(3.Beijing Research Center of Urban Traffic Information Sensing and Service Technologies,Beijing Jiaotong University Beijing, 100044, China)
Abstract It is necessary to improve the visual robust fault identification ability of roller bearing in non-stationary operating condition. To achieve it, LMD-CM-PCA approach was proposed. First, based on roller bearing vibration acceleration signals, local mean decomposition(LMD) was applied to extract product function (PF) sample matrix. Second, the discrete correntropy and Pearson product-moment correlation coefficient (PPCC) of PF and primary signal were calculated. Correntropy was modified by PPCC as the amplitude modulation (AM) of correntropy. Then, the correntropy matrix (CM) of the samples was constructed with AM-correntropy being itselements. Finally, principal component analysis (PCA) was employed to implement the integration of CM with the largest variance accumulated contribution rate as the evaluation index. Integrated CM (ICM) of vibration datum under mixed operating conditions was calculated in slight fault and serious fault situations both. The visual results indicated that ICM could isolate operating condition better and separate faults under different fault severity levels more robustly than traditional characteristics, such as energy moment and spectral kurtosis, do. Above all, application of ICM ,like roller bearing fault features provides more effective technical support for roller bearing fault intuitively diagnosis so that it can support applications in fault diagnosis and safety early warning fields.
Keywords local mean decomposition(LMD); integrated correntropy matrix(ICM); principal component analysis(PCA); roller bearing; fault diagnosis; visualization
Study of Fault Classification for Single Channel Signal Based on SDICA
CHENJianguo1,WANGZhen1,LIHongkun2
(1.Department of Mechanical Engineering, Dalian University Dalian, 116622, China)(2.Institute of Vibration Engineering ,Dalian University of Technology Dalian, 116023, China)
Abstract A fault classification method based on Subband decomposition independent component analysis (SDICA) is presented for an engineering single sensor signal. The intrinsic mode functions obtained by the empirical mode decomposition(EMD) method are used as subband signal, and are processed by independent component analysis (ICA) theory, the residual mutual information is extracted in the process of ICA separation, the approximate entropy is abstracted in the estimated subband signal acquired by the SDICA, the characteristic parameters composed by residual mutual information and approximate entropy are used as input of the generalized regression neural network (GRNN) to realize the fault classification. The SDICA import the ICA theory in the single sensor signal actual fault classification, and the engineering single channel bearing signal achieve completely correct classification of three fault type, this method proves the residual mutual information and estimated subband approximate entropy can be importent classification character.
Keywords fault classification; feature extraction; generalized regression neural network; subband decomposition independent component analysis
Experimental Researches for Broadband Piezoelectric Vibration Energy Harvester
WANGGuangqing,YUEYuqiu,ZHANYongzheng,LIXiaojun,GAOShuaishuai
(School of Information and Electronics Engineering, Zhejiang Gongshang University Hangzhou, 310018, China)
Abstract To improve the output performances of the linear resonant piezoelectric vibration energy harvester (PVEH), a two-degree of freedom broadband piezoelectric vibration energy harvester (BPVEH) is developed. The experimental setup used to test the BPVEH performances is established. The effects of the stiffness ratio and the load resistor on the output performances of the BPVEH are studied by experiments. The results have shown that BPVEH can not only broaden the operational frequency bandwidth, but also improve the output voltage and the output power by adjusting the stiffness ratio. The bandwidth of the BPVEH is 7 times of the PVEH, and the maximum output power is 4.5 times of the PVEH when the base acceleration is 40 m/s2and the load resistor is 471 kΩ.
Keywords broadband; piezoelectric vibration energy harvester; elastic magnifier; prototype model
Mechanical Study on Enveloping Characteristics for New Mechanical Elastic Wheel
WANGQiang,ZHAOYouqun,LINFen,DUXianbin,FUHongxun
(College of Energy and Power Engineering, Nanjing University of Aeronautics and Astronautics Nanjing, 210016, China)
Abstract The enveloping mechanical characteristics of new mechanical elastic wheel (MEW) were studied using the finite element analysis and test method in this paper. According to the analysis of vertical mechanical characteristics of MEW under the effect of plane and obstacles, the influence of types of cleats on variation regularity of vertical mechanical response was revealed, moreover, the reliability of the finite element model was verified. The MEW-enveloping characteristics while traversing the three different cross-section obstacles at low speed were investigated by the nonlinear finite element model and the bench testing. The vertical and longitudinal dynamic mechanical response while traversing different obstacles were illustrated, and the influence of load and types of cleats on enveloping characteristics were analyzed. The results showed that the vertical force curves were from a parabola to a camel back shape with the increase of load. The longitudinal force response increased with the increase of the load, and the curves were similar to the sine shape. And the vertical and longitudinal force response increased with the increase of the height of the obstacle. Furthermore, the vertical and longitudinal mechanical response peak was relatively low, changed slowly, and the MEW had the typical enveloping characteristics under the certain load.
Keywords mechanical elastic wheel; enveloping characteristics; vertical stiffness; cleat; mechanical response
Performance Test and Analysis of Piezoelectric Motor Drive System Based on DSP
ZHANGTiemin,LIAOYiyong,XUZhilin,LIShenghua,LIANGLi
(College of Engineering, South China Agricultural University Guangzhou, 510642, China)
Abstract In order to realize the large-stroke and high-resolution movement of advanced manufacturing industry, the new liner piezoelectric motor that composes with the ultrasonic motor and the piezoelectric ceramic drive in the structure is proposed. Therefore, the large-stoke and high-resolution drive system that achieve the integration of the macro and micro drive system is proposed. The system realizes the seamless switching between AC and DC voltage. When working in the macro-drive state, it can output two adjustable phase (-90°~90°) and adjustable frequency (10 kHz~60 kHz) AC voltage. When working in the micro-drive state, it outputs the adjustable DC voltage. The controller based on TMS320F28335 processes and controls the state of the drive system. The chip PA85 is used to form DC amplifier stabilization circuit which can output the adjustable high DC voltage for the system. According to the influences on the controlled object which has non-linear, time-varying and coupling characteristics, the control algorithm of fuzzy adaptive incremental PID is proposed. The experiments results show that the outputs of the drive system have been improved obviously by the modification of the regulator. Moreover, using the rotary ultrasonic motor and the new liner piezoelectric motor to test the drive system, the results show that the control accuracy of phase and frequency is 5°and 0.5 kHz, which can drive two types of piezoelectric motor in a good state, and has good generality.
Keywords drive system; AC/DC; macro/micro drive system; digital signal processing; PID control
Using Sub-harmonic Resonance to Detect Bolted Joint Looseness
QUWenzhong,ZHANGMengyang,ZHOUJunyu,XIAOLi
(Department of Engineering Mechanics, Wuhan University Wuhan, 430072, China)
Abstract Bolted-joint structures are prone to loosening under vibration, which affects the structural integrity. This paper presents a bolt looseness recognition method based on the sub-harmonic resonance analysis. The bolted-joint structure was simplified to a nonlinear single-degree-of-freedom (SDOF) model, and the multi-scale method was used to explain the sub-harmonic resonance. Experiments were performed on an aluminum beam with a loosened-bolted simulating the damage. Two surface-bonded piezoelectric transducers were used to generate continuous sinusoidal excitation and receive corresponding wave signals. The experimental results demonstrated that the sub-harmonic components appeared when subject to the excitation frequency twice of the natural value, which can be effective on bolt looseness damage detection.
Keywords bolt looseness; damage detection; method of multiple scales; subharmonic
Frequency Reliability Analysis for Transmission System in Engine Valve Train
YANGZhou,LIUYang,ZHANGYimin
(School of Mechanical Engineering and Automation, Northeastern University Shenyang, 110819, China)
Abstract In order to develop the performance of the transmission system of the engine's valve mechanism and to reduce the resonance invalidation,we defined the quasi-failure resonance state of the transmission system based on the rule that absolute value of difference between the natural frequency of the transmission system and the cam vibration frequency cannot go over the specified threshold. According to the perturbation theory and reliability technology,we derived the expression of the probability of the quasi-failure with normal random variables and put forward the analysis method of reliability to decrease the vibration. Finally, we set the simplified model as an example and calculated the reliability of this system with the proposed method and the Monte Carlo method respectively. Numerical results confirmed that practicability of the proposed method which can avoid the resonance invalidation of valve-train by analyzing the effect of vibration.
Keywords valve train; vibration and impact; transmission system; frequency analysis; reliability
Fault Diagnosis of Hydraulic Pump Based on Symbolic Dynamics Entropy and SVM
ZHANGHua,ZENGWentao,YANWei
(School of Machinery & Automation, Wuhan University of Science and Technology Wuhan, 430081, China)
Abstract In the light of the problem that the early fault feature signal of the hydraulic pump is weak and the fault feature is difficult to extract, a fault diagnosis method of hydraulic pump based on symbolic dynamics entropy and support vector machine(SVM) was proposed. Nine kinds of fault states of hydraulic pump were simulated, and the sample values of the vibration signal of the multi measurement points were measured then, the symbolic dynamics entropyHkof each vibration signal were calculated using time series symbolic dynamics entropy to determine the corresponding symbol dynamics entropy feature vector of each state. Finally, the training set of feature vectors in different status was established for SVM to diagnose and identify the fault state of hydraulic pump, the accuracy of the test was 98.71%.The comparison of the diagnostic results with the improved BP neural network showed that the method has a higher recognition rate of 98.71% and cost less time which helps in online diagnosis.
Keywords hydraulic pump; fault diagnosis; symbolic dynamics entropy; support vector machine
Damage Detection for Shear Frame Structure Based on the Substructure ARMAX Model
LUOJun1,LIUGang1,2,HUANGZongming1,2
(1.College of Civil Engineering, Chongqing University Chongqing, 400045, China)(2.The Key Laboratory of New Technology for Construction of Cities in Mountain Area of the Ministry of Education,Chongqing University Chongqing, 400045, China)
Abstract A damage identification method is proposed to identify the damage of a shear frame structure. First, the substructure division method is proposed based on the motion equation of the shear frame and the center difference method. Next, the order determination method of autoregressive moving-average with exogenous inputs(ARMAX) model for the substructure is proposed based on the comparison with ARMAX model and the motion equation of the substructure. Then, the vector is extracted from the elements of the ARMAX coefficient variables as a damage vector, and the Mahalanobis distance of the damage vector is defined as the damage feature. Finally, the area under a receiver operating characteristic curve is used to localize the damage and the Bhattacharyya distance is used to quantify the magnitude of the damage. Results from a simulated model and a frame structure shows that the damage location and severity of a shear frame structure can be successfully identified and a reasonable amount of noise can be eliminated.
Keywords damage detection; substructure approach; ARMAX model; shear frame structure; statistical identification
Optimal Layout of Tuned Mass Damper on Biaxial Eccentric Structure Based on Parameter Identification
HEHaoxiang1,LüYongwei1,2,HANEnzhen1
(1.Beijing Laboratory of Earthquake Engineering and Structure Retrofit, Beijing University of Technology Beijing, 100124, China)(2.Patent Examination Cooperation Center of the State Intellectual Property Office in Tianjin Tianjin, 300000, China)
Abstract The seismic responses of engineering structure can be dramatically reduced by the energy dissipation from tuned mass damper (TMD). For the actual eccentric structure, the eccentricity values are hard to be determined, however, the control efficiency will decline if the TMD is simply installed not considering the real eccentricities. Hence, the optimal install location of TMD needs to be studied in details. Under the condition that the eccentricity of actual multidimensional structure is difficult to be obtained accurately, a parameter identification method based on extend Kalman filter (EKF) is presented in order to simultaneously identify the structural mass, the horizontal stiffness and the eccentricities in two horizontal vectors, thus the optimal location of TMD can be determined based on the real physical parameter. As an example, an asymmetric reinforced concrete frame structure is analyzed based on free vibration responses and EKF, and the parameters such as the integrated eccentricities are accurately identified, and the seismic responses for different locations of TMD are compared. The results show that the parameters can be identified accurately with EKF, and best control rate can be obtained after choosing the rational locations, this method has superior feasibility in engineering practice.
Keywords seismic control; eccentric structure; tuned mass damper; parameter identification; extend Kalman filter
Analysis of Mode and Vibration Fatigue Life of Beam with Multiple Cracks
MAYijiang,CHENGuoping
(State Key Laboratory of Mechanics and Control for Mechanical Structures,Nanjing University of Aeronautics and Astronautics Nanjing, 210016, China)
Abstract An analytical method is proposed to predict the fatigue life of the beam with multiple cracks based on the Paris equation. In the modal analysis process, the segment of cracks is replaced with bending springs, a new method for solving natural modes of the beam with multiple cracks is proposed based on the transfer matrix method, and the effect of the number, locations and depths of cracks on the natural frequency of the cracked beam is analyzed. In the vibration fatigue analysis, the effect of the number of cracks on the crack-tip stress intensity factor under harmonic excitation is analyzed. Considering the interaction of cracked beam vibration and fatigue crack growth, the effect of the number and the location of the cracks on the cracked beam fatigue life is analyzed based on timing analysis and Paris equation. The results indicate that the number, locations and depths of cracks have important effects on the modal parameters and the fatigue life of the structure.
Keywords cracked beam; transfer matrix method; natural frequency; vibration fatigue
Study on Vibration Characteristics of Marine Steam Turbine Rotor Shaft Coupling With Disk
SUNYuanli,LIZhaojun
(Naval Academy of Armamant Beijing, 100161, China)
Abstract Base on small aspect ratio modeling theory, the finite element of rotor shaft coupling with disk was established, and the vibration characteristics of marine steam turbine rotor were analyzed with different modeling methods such as oblique cutting way and disk unit. Then, the significant influences of different modeling methods on the vibration characteristics of the rotor system were studied. The additional modes of rotor bearing system generated by disk unit represented as coupling vibration mode between disk and rotor shaft. The calculation method based on disk-unit model accurately described the vibration characteristics of the rotor shaft coupling with disk. For thicker disk, the disk had less effect on the rotor coupling vibration. The oblique cutting model commonly used in engineering generated additional stiffness and caused larger error in the solving process. This kind of error gradually reduced with the decreasing of the disk thickness.
Keywords rotor shaft coupling with disk; finite element model; disk element; vibration characteristics
Dynamic Analysis of a Flexible Nonlinear Synchronous Vibration Pile System
ZHANGNan1,QIUYanchao1,ZHANGXueliang2,WENBangchun2
(1.Beijing Key Laboratory of Performance Guarantee on Urban Rail Transit Vehicles, Beijing University of Civil Engineering and Architecture Beijing, 102616, China)(2.School of Mechanical Engineering and Automation, Northeastern University Shenyang, 110819, China)
Abstract The dynamic characteristics of the flexible nonlinear synchronous vibration pile system were studied. The nonlinear dynamic models of the system were proposed to analyze the nonlinear stiffness of the soil, which were induced by the relationship between the nonlinear stress and the strain in the soil. The periodic solutions of the system were investigated using Lyapunov function of the amplitude-frequency characteristic equation for the nonlinear models. The amplitude-frequency characteristics were analyzed through the selected parameters. The dynamic characteristics of the system were presented for the changes of system parameters (including the vibrating frequency, the stiffness of the soil and the damping of the soil, the radius of the eccentric block), which are induced by the amplitude-frequency characteristics. Finally, the stable solution of multiple periodic solutions can be obtained by the different initial conditions, using Runge-Kutta method. The stability of periodic solutions was theoretically analyzed by theory and verified by simulation, and the influence of different parameters on the periodic solution was presented.
Keywords nonlinear vibration; amplitude frequency; stability; synchronous vibrating pile system
Wind-Induced Responses Analysis for the Typical Transmission Tower with Narrow Base Based on an Aero-Elastic Model Wind Tunnel Test
ZHANGQinghua1,MAWenyong2,ZHAOLong2,3
(1.School of Civil Engineering and Communication, North China University of Water Resources and Electric Power Zhengzhou, 450000, China)(2.Wind Engineering Research Center, Shijiazhuang Tiedao University Shijiazhuang, 050043, China)(3.CRL Group, China Railway Tunnel Survey & Design Institute Co., Ltd Tianjin, 300133, China)
Abstract Based on the discrete stiffness method, aero-elastic model for the typical transmission tower with narrow base (TTNB) was firstly made. Then the displacements and accelerations of the TTNB under various heights and wind directions were investigated through boundary layer wind tunnel tests. Finally, based on the wind tunnel test data, the wind-induced vibration coefficients of TTNB were calculated and compared with Chinese architectural structure load standards. The results showed that the mean displacements on the TTNB were mostly in the along-wind direction; but, the along-wind and across-wind fluctuating displacements and accelerations were in the same order of magnitude and cannot be ignored. Moreover, the fluctuating responses did not change remarkably with the variation of wind directions; however, the heights above ground had different influence on fluctuating displacements and accelerations. In addition, since the high-order modes had influence on the dynamic displacement responses, the wind-induced vibration coefficients which were only deduced from the first-order displacement response would be lower. And the wind-induced vibration coefficients obtained from Chinese architectural structure load standards were bigger than that from the wind tunnel tests.
Keywords transmission tower; aero-elastic model; wind tunnel test; wind-induced responses; wind-induced vibration coefficients
Vibration State of Remanufactured Engine Based on Sensitive IMF
CHENChengfa1,2,BAIYunchuan1,ZHANGYingfeng1,JIAOYufei1,LIShumin1
(1.Department of Automobile Engineering, Military Transportation University Tianjin, 300161, China)(2.State Key Laboratory of Precision Measuring Technology and Instruments, Tianjin University Tianjin, 300072, China)
Abstract In order to improve the quality of remanufactured engine, ensemble empirical mode decomposition(EEMD) decomposition and sensitive intrinsic mode function(IMF) selection algorithm is introduced in the study of remanufactured engine performance. Based on the EEMD decomposition, interrelated coefficient is drawn into the study of IMF, the interrelation between the IMF weight and original signal is analyzed, the original signal IMF weight’s sensitive determination is computed, then the sensitive IMF Hilbert commutation is used, and the vibration condition is analyzed. The results show that, using the EEMD decomposition algorithm and sensitive IMF marginal spectrum can reflect the vibration state on different parts of remanufactured engine. Cylinder, cylinder head, crankshaft, the sensitive frequency region of these three parts is different. Through the study of vibration condition of main parts, using manufacture technology, thus providing technology to improve Remanufactured Engine level.
Keywords sensitive IMF; vibration state; remanufactured engine; marginal spectrum
Feature Extraction Method Based on Empirical Mode Decomposition and Bispectrum Analysis
JIANGYonghua,LIRongqiang,JIAOWeidong,TANGChao,CAIJiancheng,SHIJizhong
(Institute of Precision Machinery, Zhejiang Normal University Jinhua, 321004, China)
Abstract In view of the deficiency of traditional bispectrum that has good insensitivity to independent Gaussian noise but is incapable of avoiding the disturbance of non-Gaussian noise, a new feature extraction method based on EMD and bispectrum analysis is proposed. Firstly, decompose the signal by EMD. Then, energy-related method is applied to removal the illusive intrinsic mode functions (IMFs) of EMD. Finally, bispectrum analysis is applied to the real IMFs to extract the fault feature. The results of experiment and practical signals analysis show that the proposed method is feasible and effective for extracting feature of rolling bearing, and it is more effective compared with traditional power spectral analysis and traditional bispectrum analysis.
Keywords empirical mode decomposition(EMD); bispectrum analysis; energy-related; feature extraction; intrinsic mode function(IMF)
Investigation on Longitudinal Vibration of Hollow Shaft Based on Dynamic Vibration Absorber
ZHAOShuai,CHENQian,YAOBing
(State Key Laboratory of Mechanics and Control of Mechanical Structures,Nanjing University of Aeronautics and Astronautics Nanjing, 210016, China)
Abstract With the increasing size of ship, the damage of the longitudinal vibration of shaft is increasingly exposed. This paper adopted a damping vibration absorber to attenuate longitudinal vibration of the hollow shaft system, established the dynamic model of shaft with dynamic vibration absorber combining with the substructure synthetic method and transfer matrix method, and analyzed the frequency response function of shaft under harmonic excitation, which is verified by the traditional finite element method using ANSYS software. The theoretical calculation and simulation results showed that the frequency response function curve near the resonance frequency turned to smooth by adding dynamic vibration absorber. A dynamic vibration absorber is designed and then an experimental verification is conducted. The testing results show that the resonance peak is strongly attenuated when dynamic vibration absorber attached to the shaft, which indicates the attenuation effect of dynamic vibration absorber is obvious. Based on hollow characteristics of a large marine propulsion shafting system, a DVA can be installed into the void location of the hollow shafting, which saves space and has a good absorption performance, can be a new choice in the control of longitudinal vibration of marine propulsion shafting system in future.
Keywords hollow shaft; longitudinal vibration; dynamic vibration absorber; transfer matrix method; substructure synthetic method
Study on Effect of Subsystem on Vibration Isolation Performance of Two-Stage Vibration Isolation System
CHENJun1,YANBing1,SUNMeiyun2,SHIWeizhen1,LUZhiwen1,DONGDawei1
(1.School of Mechanical Engineering, Southwest Jiaotong University Chengdu, 610031, China)(2.Tangshan Railway Vehicle Co., Ltd Tangshan, 063000, China)
Abstract Since there is little study on subsystem parameters design for powerpack two-stage isolation system attached with a subsystem, experimental method was adopted to tackle the situation. Effects of subsystem parameters (isolator general stiffness, isolator damp, isolator stiffness ratio) on vibration isolation performance and dynamic characteristics of a certain diesel multiple unit powerpack two-stage vibration isolation system were studied. The results showed that the powerpack two-stage vibration isolation system had excellent vibration isolation performance in both conventional condition and shutdown condition of engine when the subsystem act as a vibration absorber of the main system. And a better vibration isolation performance can be obtained with proper value of the stiffness of subsystem isolators, damping and stiffness ratio.
Keywords subsystem; diesel multiple unit powerpack; two-stage vibration isolation system; vibration isolation performance
Rapid Precision Diagnosis of Non-uniform Scroll Part Based on Reverse Engineering
WUZaixin,LIUTao,WUJun
(School of Mechanical and Electronical Engineering, Lanzhou University of Technology Lanzhou, 730050, China)
Abstract Non-uniform scroll parts are more difficult to be examed with traditional fixtures and calibration precision is relatively low because of their compicated shape. In response to the above feature, an approach of rapid precision diagnosis of non-uniform scroll part based on reverse engineering is presented. First a 3D solid model of non-uniform scroll part was created in the Pro/E environment and used as the reference model, and then cloud data of the scroll part machined was collected using the ROMER measuring arm and treated as digital model. The two models are compared to abtain machining precision information of the scroll part. Graphics-directed matching principle of mathematical models is proposed to improve alignment precision of the digital model. In this approach, alignment of multi-look cloud data, de-noising of scattered cloud data and data compacting integrated by random and curvature sampling are adopted to decrease the data-processing error. Analysis of 2D, 3D and geometric tolerance evaluation between the reference and digital models show that the machining precision and geometric tolerance of the presented non-uniform scroll part are satisfied. This study provides a rapid, accurate and visual method of precision diagnosis for complex-surfaced mechanical products.
Keywords reverse engineering; non-uniform scroll part; precision diagnosis; cloud data; digital model
The Blade Vibration Measurement Research Based on the Key Phase Interpolation Method
WANGWeimin,RENSanqun,CHENLifang,SHAOHuajin
(Beijing Key Laboratory of Health Monitoring Control and Fault Self-recovery for High-end Machinery,Beijing University of Chemical Technology Beijing, 100029, China)
Abstract This paper studied the effect of speed fluctuation on the accuracy of blade tip timing and corresponding solution. Based on the method of blade tip timing (BTT), key phase interpolation method is introduced to solve the larger error caused by speed rise (deceleration) or speed fluctuation with once per revolution probe, while it can also be adaptive under the constant speed operation. First, the simulation model was established to compare the results of the key phase interpolation method with the result of the single phase under different frequencies and speed fluctuations. Finally, tests were carried out by the simulant test platform and real impeller test bench. The results showed that the accuracy of results were significantly improved by using key phase interpolation method when the fluctuation period was large or the amplitude of rotation speed fluctuation was big. Because the vibration signal may be affected by the rotor axial displacement, test data in real impeller test bench needs further research.
Keywords blade tip timing (BTT); blades vibration; speed fluctuation; once per revolution probe; key phase interpolation method (KPIM)
Model Updating and Validation for Bearing-Rotor System at Working Speed Considering Model-Form Error
ZHANGBaoqiang1,GUOQintao2,YUANXiukai1
(1.School of Aerospace Engineering, Xiamen University Xiamen, 361005, China)(2.College of Mechanical and Electrical Engineering, Nanjing University of Aeronautics & Astronautics Nanjing, 210016, China)
Abstract Structure dynamical model updating and validation for bearing-rotor system at working speed considering model-form error is presented. The theory of model-form error, model updating based on complex eigenvalue sensitivity analysis is successfully accomplished in this piece of work. The updating for simulation example about flexible rotor-bearing system at working speed, considering model-form error, is performed to bearing stiffness, bearing damping and diameter moment of inertia parameters using wheel frequency and damping as objective residues. The updated model is validated through unbalance response prediction. The simulation results show that the maximum residual errors of updated parameter is still -10.1%, but the maximum residual errors for the real part of updated eigenvalue is 0.95% and for the imaginary part is -1.15% even taking into 2% model-form error account in model updating. The unbalance response prediction of the updated model matches the target model unbalance response quite well. The results, in no doubt, proved the effectiveness and robustness of the model updating method considering model-form error using wheel frequency and damping for bearing-rotor system at working speed.
Keywords model updating; model-form error; rotor dynamics; working speed; validation
Displacement Measurement of Free-Piston Stirling Engine Based on Strain Gauge
LIWei1,2,MOUJian1,2,HONGGuotong1
(1.Technical Institute of Physics and Chemistry, Chinese Academy of Sciences Beijing, 100190, China)(2.University of Chinese Academy of Sciences Beijing, 100049, China)
Abstract Combining the structure characteristics of free-piston Stirling engine, a kind of dynamic displacement measurement that the strain gauge are used to measure indirectly the displacement of displacer and piston by responding to shape change of plate spring is put forward. On the basis of strain-resistance effect and bridge principle of strain indicator, a set of dynamic displacement measurement system based on strain gauge is built up, and experimental data are compared with the data gotten from static displacement measurement. The experimental testing results indicate the data from dynamic displacement measurement are not exactly the same as the data from static displacement measurement, and the attaching position of strain gauge directly affected the accuracy of measurement.
Keywords free-piston Stirling engine; dynamic displacement measurement; strain gauge; plate spring
Analysis Method for Discretization Dynamics of TRUM with Stator Teeth Structure
SUNHexu1,2,3,JINGKai1,2,DONGYan1,2,LIGuoqing1,2
(1.School of Control Science and Engineering, Hebei University of Technology Tianjin, 300130, China)(2.Hebei Control Engineering Technology Research Center Tianjin, 300130, China)(3.School of Electrical Engineering, Hebei University of Science and Technology Shijiazhuang, 050018, China)
Abstract This paper puts forward an analysis method for the dynamics of the contact interface of travelling-wave rotary ultrasonic motors (TRUMs) by discreting the stator/rotor interface to avoid the complexity non-linear deduction of the motor in the recent researches. First, the surface-contact of each stator tooth was equivalent to point-contact, for which the concept of equivalent stiffness of different contact states was proposed to analyze the contact states. The discrete axial forces between the stator teeth and rotor were described as the equivalent stiffness, and the equivalent force between the stator and the rotor was obtained. Thus, the relative movement of the stator and the rotor was calculated, and the axial dynamics characteristics of the stator and the rotor were gained. Then, the radial and circumferential friction was given by the three-dimensional motion in the interface to study the mechanical characteristics and the energy consumption. The final simulations and experiments demonstrated the accurate description of the interface dynamics by the proposed method.
Keywords travelling-wave rotary ultrasonic motor; stator teeth; contact interface; discretization; dynamics
ANFIS Method to Remove Background Vibration from Traffic Environment Vibration Measured Data
GENGChuanfei1,2,LUWenliang1,YUXing3
(1.School of Civil Engineering, Beijing Jiaotong University Beijing, 100044, China)(2.China Railway Siyuan Survey and Design Group Co.,Ltd Wuhan, 430063, China)(3.Jin Liwen Railway Limited Liability Company Wenzhou, 325003, China)
Abstract In the field of data test, environment vibration signals induced by rail transit and background vibration signals are inseparable. A new adaptive neuro-fuzzy inference system (ANFIS) method is put forward. Basic principle to banish background vibration is discussed, and the implementation steps of ANFIS are determined. A background vibration acceleration time history is superimposed on a ground vibration induced by a train to synthesize a testing field vibration record, which is used to remove background vibration by the proposed ANFIS method and other existing methods. The comparative analysis of results is carried out. The root mean square errors of time history curves calculated by these methods are 0.414 mm/s2with the Fourier amplitude revising method, 0.363 mm/s2with the auto power spectral density (PSD) method, 0.261 mm/s2with auto-cross PSD method and 0.074 mm/s2with the proposed ANFIS method, respectively. The error of ANFIS method is minimal. Also the weighted vibration levelVLzvalues are 63.842 dB with vibration level revising method, 62.894 dB with Fourier amplitude revising method, 63.859 dB with auto PSD method, 63.802 dB with auto-cross PSD method and 63.805 dB with ANFIS method, respectively. The calculation value of ANFIS method is the closest to real value 63.815 dB. The results show that the time history, Fourier spectrum, power spectral density and vibration level obtained with the new ANFIS method are extremely close to true ones of traffic vibration, and the errors are relatively smaller than those of other existing approaches.
Keywords rail transit; environment vibration; measured data; background vibration; adaptive neuro-fuzzy inference system (ANFIS) method; auto power spectral density (PSD) method; auto-cross power spectral density (PSD) method
Fatigue Analysis for Bogie Frame Based on Rigid-Flexible Coupling Simulation
LIAOAihua,HUANGXu,FANGYu
(College of Urban Railway Transportation, Shanghai University of Engineering Science Shanghai, 201620, China)
Abstract Bogie frame is one of the important parts of an urban subway vehicle, but it usually occurs to fatigue crack. Traditional dynamic characteristic analysis for bogie frame is generally based on multi-body dynamics simulation and finite element analysis, this method is suitable for the structural natural frequency away from the external loading frequency, consequently its result has certain limitations. In order to study dynamic response characteristics and fatigue strength of a bogie frame,a rigid-flexible coupled multi-body dynamic model of the bogie frame is established based on the finite element analysis method and the rigid-flexible multi-body dynamics theory. The dynamic stress response of bogie frame is carried out based on rigid-flexible coupling multibody dynamic model of the metro vehicle, from which vibration characteristics of this type of the bogie frame can be obtained. Then, failure mechanism of the bogie frame can be obtained based on fatigue analysis of local fatigue areas of the bogie frame. The stress time histories of its bogie frame necessary for fatigue analysis are calculated with the results of the multi-body dynamic simulation taken as the dynamic load by using the finite element analysis method. The fatigue life of the bogie frame is predicted by using the quasi-static stress superposition method. The calculation results show regions of the bogie frame with excessively large stress amplitude are concentrated on the motor hanger region, gear box hanger region and the connected region between the beam and side beams. The simulation result conforms to the location of actual fatigue bogie damage on this frame, thus verifying the correctness of the method on structure fatigue analysis based on the rigid-flexible coupled model. The shortest lifetime of the motor hanger obtained from the simulation is 1 530 000 km. The error of the result of simulation and the actual data is 10%, which illustrates high credibility and accuracy of the simulation.
Keywords bogie frame; multi-body dynamics; rigid-flexible coupling; fatigue life
(End of the Volume 36)
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The high firing precision has been continuously required by modern war for weapon systems such as multiple launch rocket system, artillery, tank and armored vehicle. However, bad firing precision, huge consumption of rockets in test and launch unsafety are hard technical problems restricting the development of these modern weapon systems. The firing precision and the launch safety depend on dynamics of the corresponding weapon system. As an engineering subject studying the motion and force for weapon system during launch process, launch dynamics has been a novel sally port to improve the firing precision and to ensure launch safety of weapon systems. In this paper, the theory and technology of launch dynamics of multibody system as well as its applications in the design and test of firing precision and safety for weapon systems are studied. It can provide new theory and technology for the design and test of firing precision and safety of weapons.
firing precision; consumption of rockets in test; launch safety; launch dynamics of multibody system; transfer matrix method for multibody systems
*上海市研究生教育創(chuàng)新計劃學位點引導布局與建設培育資助項目(13SC002);上海市自然科學基金資助項目(15ZR1419200)
2015-04-01;
2015-05-21
10.16450/j.cnki.issn.1004-6801.2017.02.030
TH113
廖愛華,女,1978年1月生,博士、副教授。主要研究方向為車輛結構動力學、有限元分析及車輛故障診斷等。曾發(fā)表《A numerical simulation of elastoplastic contact analysis of compressor by overspeeding》(《Advances in Mechanical Engineering》2014,No.4)等論文。 E-mail:aiwa7816@126.com
New Developments in Launch Dynamics of Multibody System and Its Applications
RUIXiaoting
(Institute of Launch Dynamics, Nanjing University of Science and Technology Nanjing, 210094, China)