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XX 大學畢業(yè)設計文獻翻譯與原文題目： 鐵路車輪對的輔助磁檢測學 院： 測試與光電工程學院專業(yè)名稱： 測控技術與儀器班級學號： 學生姓名： 指導教師： 二〇xx 年四月鐵路車輪對的輔助磁檢測摘要：在工件制作的過程中，車輪對檢測可以采取許多不同的缺陷檢測方法。然而這些方法在車輪在役使用時是不夠的。這篇論文旨在介紹一種針對車輪對的圓弧表面磁參數(shù)變化的檢測案例。這些圓弧表面磁參數(shù)的變化是由于材料的老化，而材料老化是由于材料疲勞造成的。1.簡介：到目前為止測試車輪制造過程中通過 x 射線(RT),超聲波(UT),渦流(ET)和磁(MT)。洛氏、布氏硬度測試也是非常重要的。在鐵路車輛操作的基本方法診斷車輪超聲和渦流的方法。然而,即便是這種復雜的檢驗流程的使用確保轉向架的完整可靠性和底盤和車輪組關節(jié),作為鐵路的記錄在分析已知的情況下失敗。本文給出的方法要求鐵路輪對的進一步診斷。該方法測試 PKP 車輛維護植物。提出測試是基于鋼的鐵磁特性以及magneto-mechanical 效應和磁過程發(fā)生在材料由于疲勞和引起的退化。這個新的診斷是一個獨特的有價值的補充的檢驗,特別是車輪的滾動表面測試。額外的測試基于測量的切向分量在滾動表面磁場強度檢測有害內應力及其發(fā)展隨著時間的推移以及材料的物理參數(shù)的變化由于操作不當。2.制造過程中的缺陷檢測控制輪集,車輪中心、實心輪子和輪胎的復雜過程，非常有限的概率失敗的組件使用。不同的診斷方法通常應用[1]。如 Tab.1 表示。制造過程的車輪組成分測試檢測方法檢測元素射線 硬度測試 幾何測量 超聲檢測 磁檢測 渦流檢測輪胎 X X X X X車輪中心 X X X X X實心輪 X X X X X車輪組 X X X X X這些方法導致消除塊材料不連續(xù)(缺陷),微觀結構變化和由輪或輪中心材料硬度的變化而引起的內部應力。UT 和 RT 可以用來檢測散裝材料,而磁檢測則用來檢測材料的表層和次表層。3.車輪組在役檢測對于高速列車的輪組在役檢測，主要是集中在循環(huán)檢查,當滾動表面的幾何已經(jīng)被評估過的時候。滾動表面的磨損情況表明,了車輪和軌道的相互作用。在檢查或維修的期間,磁檢測和超聲檢測大多用于車輪組檢測(車輪組保留或拆除)——Tab.2。車輪組成分的在役檢測超聲波(UT)可以穿透車輪輪胎并且檢測深度范圍為 10 毫米甚至更深層次,而渦流測試(EC)可以覆蓋表面開始向下 10 毫米的厚度層。選擇適當?shù)臏u電流探針頻率檢測到材料的不連續(xù)而非結構性變化。在選擇的頻率范圍內這種變化并不是“可見” 。4 在役疲勞檢測當車輪組在使用時,滾動面上層容易出現(xiàn)變化。這些都是結構變化以及磁性和力學參數(shù)的變化。這些可以表明在使用過程中在輪組的滾動表面積累的疲勞應力。常見的診斷程序對材料結構不敏感。車輪材料進行調查的幫助下 BEMI(巴克豪森噪聲和渦流顯微鏡)的弗勞恩霍夫研究所(Saabrucken,德國)。用頻率大于 1,5 MHz 的渦流檢測模塊(3、4)(圖 2)檢測接觸載荷引起的材料結構的變化(圖 1)。表一，輪胎材料結構樣品 PA 和 PB表二本 pA 和 pB 以及振幅軌跡曲線在不同的操作頻率下的 BEMI 渦流圖像樣檢測方法待檢測元素射線檢測硬度測試幾何測量超聲檢測磁檢測 渦流檢測車輪 X X X車輪組 X X X5.以漏磁場作為診斷媒介的檢測曲面表面的磁漏磁場測量是按照材料的反映了不同機械材料的條件的磁導率來進行的。這可能也就解釋了顯示初始磁化曲線的變化:材料樣本取自一個新的車輪(已經(jīng)聚集在方向盤前)和材料樣品接觸影響加載在?阿姆斯勒試驗臺(Fig.3a)。硬材料樣本來自一組車輪在方向盤上(Fig.3b)圖 2.材料的磁參數(shù)的變化進行變形和硬化(a)新鮮和退化的材料(b)+圖 3.材料的磁參數(shù)的變化進行變形和硬化(a)新鮮和退化的材料(b)+在這兩種情況下矯頑力 Hc 的增加和材料磁導率的減少是可觀察的[5]。可以檢測可塑體沿著滾動表面的變化,內部壓力的影響[5]以及相變材料由于材料的磁參數(shù)和磁化強度的變化而引起的變化是可以測量的。為了達到這個結果，測量車輪的滾動表面在外部磁場(例如地球磁場)的磁場強度是必要的(Ht)。然而,重復測量只是確保當?shù)嘏c標準磁場磁軛磁化和探針(校準)檢測磁化強度的變化,如圖 4所示。材料的磁性參數(shù)的變化的檢測擴展了已知的輪軸檢測方法。目前在鐵路工程部門，實驗室和鐵路維修和保養(yǎng)工作都在進行研究。一些博士論文也提到了這種研究。圖 5顯示:測試的數(shù)值模擬,b)測試平臺,c)新車輪磁漏磁場測量的結果,和 d)的磁漏磁場測量結果輪表面受損(物質結構的變化)。在磁測量過程中的車輪組的附加信息提高了診斷的可靠性,特別是在輪軸操作。這反過來增加了鐵路運輸安全。6.結論在輪對診斷中引入附加的磁性測試為材料的不連續(xù)以及結構性變化(同質性)檢測提供了附加的信息。在確保適當?shù)母咚倭熊嚨陌踩院筒僮髦?，這是必要的。表 3 列出了能提高診斷的可靠性的新的測試方法,檢測方法檢測元素 幾何測量 超聲檢測 磁檢測 渦流檢測車輪 X X X X車輪組 X X X X提出的可靠性檢驗應該被鐵路安全當局驗證。擴大現(xiàn)有的測試平臺通過添加一些測試探頭，并沒有顯著增加質量成本。SUPPLEMENTARY MAGNETIC TESTS FOR RAILWAY WHEEL SETSSummary: During manufacturing process the wheel set is subjected to many different flaw detection methods; however, these methods are not sufficient while the wheel set is in service. The paper presents an example of monitoring of magnetic parameters changes of wheel set rolling surface (changes result from material degradation due to material fatigue).1. INTRODUCTIONSo far testing the wheels during the manufacturing process has been done by X-ray (RT),ultrasound (UT), eddy currents (ET) and magnetic (MT) . Rockwell or Brinell hardness tests are also very important. During rail vehicle operation the basic methods of diagnosing the wheels are ultrasound and eddy current methods. However, even the uses of such sophisticated inspection processes do not ensure full reliability of the bogie and undercarriage and the wheel set in articular, as documented in analysis of known cases of railway failures. The method presented in the paper asks for a further step in the railway wheel sets diagnostics. This method is tested in the PKP rolling stock maintenance plants. Proposed tests are based on the ferromagnetic properties of the steels as well as on magneto-mechanical effects and magnetic processes occurring in the material and caused by degradation due to fatigue. This new diagnostics is a distinct valuable supplement of the wheel inspection and especially of the wheel rolling surface tests. Additional tests based on the measurement of the tangential component of the magnetic field intensity at the rolling surface detect harmful internal stresses and their development with time as well as change in the physical parameters of the material due to improper operation.2. WHEEL SET DIAGNOSTICS DURING MANUFACTURING PROCESSThe complex process of controlling wheel sets, wheel centers, monobloc wheels and wheel tires has tremendously limited the probability of failure of the used components. Different diagnostic methods are usually applied [1]. They are indicated in Tab.1.Wheel set components testing during manufacturing processThese methods result in eliminating pieces with material discontinuities (flaws), microstructure changes and internal stresses defined by change in wheel or wheel centre material hardness. UT and RT allow to inspect the bulk material, while by MT a check of the surface and subsurface layers is only performed.3. WHEEL SET OPERATIONAL DIAGNOSTICSWheel set operational diagnostics (for high speed trains) is mostly focused on cyclic inspections,when the rolling surface geometry is assessed. Rolling surface wear shows how wheel and track interact. During inspection or repair cycles ET and UT are mostly used for wheel set testing (wheel sets either remain in place or are dismantled) – Tab.2.Ultrasonic waves (UT) penetrate the wheel tire material and inspect a depth range of 10 mm and deeper, while eddy currents tests (EC) can cover the 10 mm thick layer beginning at the surface. Eddy current probe frequencies are selected so that the tests will detect any material discontinuity rather than structural changes. Such changes are not “visible” in the frequency range under consideration.4. FATIGUE PROCESSES DETECTIONWhen the wheel set is in operation, changes emerge in the rolling surface upper layer. These are structural changes as well as magnetic and mechanical parameter changes. These can indicate the fatigue processes which accumulate in the wheel set’s rolling surface. The common diagnostics procedures are not sensitive to the material structure. The wheel set materials were investigated withthe help of BEMI (Barkhausen Noise and Eddy Current Microscope) in the Fraunhofer Institute (Saabrücken, Germany). Detection of contact load induced changes in the material structure (Fig.1)were detected by the implemented eddy current module for frequencies greater than 1,5 MHz [3,4](Fig.2).5. MAGNETIC LEAKAGE FIELD USED AS A DIAGNOSTIC MEDIUMThe magnetic leakage field measured at the rolling surface varies in accordance with material’s magnetic permeability, which in turn reflects the mechanical material’s condition. This may be explained by example showing changes in initial magnetisation curves:Material sample taken from a new wheel tire (before it has been assembled at the wheel) and material sample subjected to contact oads at AMSLER test rig (Fig.3a).Hardened material sample taken from a wheel tire set on the wheel (Fig.3b)In both cases also a significant increase in the magnetic coercion Hc and a decrease in material’s magnetic permeability are observed [5]. It is possible to detect changes in plastic strains along the rolling surface, impact of internal strains [5] as well as the phase changes of the material due tochanges in material’s magnetic parameters and magnetisation. In order to attain this result it is sufficient to measure magnetic field intensity (Ht) only along the wheel’s rolling surface in the external magnetic field (e.g. Earth’s magnetic field). However, a good measurement repeatability is only ensured by a local yoke magnetisation and with standard field probes (calibration), detecting magnetisation changes as shown in Fig.4.Detection of changes in material’s magnetic parameters extends the range of known wheel set testing methods. Research is currently carried out in the Railway Engineering Department on a laboratory scale and in railway repair and maintenance works. Some investigation is performed also within a Ph.D. thesis.Fig.5 shows: a) the numerical simulation of the test, b) the test rig, c) the results of the magnetic leakage field measurements for a new wheel, and d) the results of the magnetic leakage field measurements for a wheel with a damaged surface (change in material structure).Additional information on the wheel set condition originating from magnetic measurements increases the diagnostic reliability, in particular during wheel set operation. This in turn increases rail transport safety.6. CONCLUSIONSIntroducing additional magnetic tests to operational wheel set diagnostics provides additional information on material discontinuity as well as on structural changes (homogeneity). This is essential in order to ensure proper safety and operation of high speed trains. Table 3 sets out new testingmethodology which will increase diagnostic reliabilityThe reliability of the proposed inspection should be validated by railway safety authorities.Expanding existing test rigs by adding some test probes does not significantly increase the quality costs。