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1、 畢業(yè)設(shè)計(jì)（論文）外文資料翻譯 學(xué)院： 機(jī)械工程學(xué)院 專(zhuān)業(yè)： 機(jī)械設(shè)計(jì)制造及其自動(dòng)化 班級(jí)： 機(jī)113班 姓名： 學(xué)號(hào)： 2011307310 外文出處： Availabie online at www.sciencedirect U

2、ltransonics 42(2004) 169-172 附 件：1、外文原文；2、外文資料翻譯譯文。 指導(dǎo)教師評(píng)語(yǔ)： 簽字： 年 月 日 附件1： Friction generated ultrasound from geotechnical materials Abstract Drilling is a process involved with product manufacturing and for civil engineers, site prepar

3、ation. The usual requirement is for efficient material removal. In this study, the friction pair interaction generated by a drilling process provides ultrasound information related to parameters for the geotechnical material being drilled, where the drill bit has non-degrading ultrasonic characteris

4、tics and no essential requirement for material removal. This study has considered monitoring the ultrasonic signal generated by drilling process, with a view to characterising the parameters of the geotechnical material being drilled and provides a novel method to identify or characterise ground str

5、uctures. Drilling of geotechnical material systems, typically involve the interaction of a rotating probe and a granular composite medium. The applied load and angular velocity are measured to determine their relevance to the ultrasonic signal. Samples of granular materials have been graded into con

6、trolled grain size ranges. Attention has been focused on determining the effects on the ultrasound signal of grain size, bulk density and the water content of the granular material. A comparison between the various granular samples of the different grain sizes, density, water content and the associa

7、ted ultrasonic signal has been done. The effect of each variable, and existing theory for these effects is commented upon. The broad aim of this research is to evaluate ultrasonic monitoring of drilling and assess its potential for real-time geotechnical ground condition monitoring applications and

8、offer it as an alternative to existing methods. _ 2004 Published by Elsevier B.V. 1. Introduction The ultrasound generated from a solid–solid friction pair has been the main focus of research concerning friction-generated ultrasound, mainly associated with rotating and reciprocating machines.

9、 A frictional process developed during relative movement between contacting materials has an inherent level of wear that eventually would result in failure. Monitoring the ultrasonic signal generated from machinery has become an alternative condition-monitoring tool, as the generated signal contains

10、 information related to the microcondition of the friction pair. It is possible to detect when components of a machine are becoming worn and a thus reduce the risk of catastrophic failure leading to production down time. Holroyd and Randall [1] discussed the sensitivity of using acoustic emission (A

11、E) for detecting changes in lubrication, overloading, wear and review a number of different techniques used to analysethe acoustic signature. Further methodologies for analysing the friction generated acoustic signatures were discussed by Bukkapatnam et al. [2] and provide a novel analysis technique

12、 based on chaos theory, wavelets and neural networks. Much of the research concerning condition monitoring focuses on the changes in the signal due to wear, but some research have also focused on the parameters associated with the generated acoustic signal.Work by Diei [3] monitored the acoustic emi

13、ssion generated by tool wear during face milling and proposed a power function relationship between the AERMS voltage and the rate of frictional energy dissipationgiven by AERMS ekgssAaV Tm=2 e1T where k and m are constants that depend on the AE measuring system and the material properties of the f

14、riction pair, g is a function of surface roughness and elastic properties of the friction pair, ss is the shear strength of the interfacial material, Aa is the visible area of contact and V is the sliding velocity. The parameters g and Aa essentially define the real area of contact andtherefore, the

15、 AERMS is a function of the real area of contact, the shear strength and the sliding velocity. Results obtained by Diei’s work also indicated a linear relationship between the AERMS and the sliding velocity. Jiaa and Dornfield [4] monitored the AE generated by a pin on disk experiment, highlighting

16、 that the AE is caused by impulsive shock due to asperity collisions and micro-vibrations excited by stick–slip phenomena. The research shows that the AERMS increases with load while a linear relationship exists between the relative surface velocity and the AERMS. Sarychev and Shchavelin [5] describ

17、e the frictional process and the generated acoustic emission associated with it. Two general rules were established relating the rate of counting the acoustic pulses (count rate) to the sliding speed of the friction pair and the applied load. The general rule for the dependence of the count rate

18、N_ on the sliding velocity is in the form: N_ A t BvX e2T where A and B are constants and X P1. A similar relationship also applies for the dependence of the load on the count rate, but the exponent X 61. A further relationship was expressed relating the AE activity to the regime of friction in ela

19、stic contact: N_ a k N0:71h0:71A0:71 c r0:90R1:60 a V e3T where N is the normal load, h the generalised elastic modulus, Ac the counter area of contact, r the surface asperity tip radius, Ra is the surface roughness and k is a coefficient of proportionality. Further work by Baranov [6] produced two

20、 models relating the frictional parameters of the friction pair to the acoustic parameters; count rate and acoustic energy. The model for the count rate is based on the assumption that the rate of counting acoustic pulses is directly proportional to the number of contact points formed per unit time.

21、 Work by Henrique et al. [7] studied particle collisions down an inclined slope and the number of acoustic events were used to monitor the number of collisions (contacts) generated when a ball was rolled down the slope. The model for the acoustic energy relates the mechanical potential energy genera

22、ted during the elastic deformation of a contacting asperity to the amplitude distribution of the acoustic signal. The energy model does not take into consideration the effects of wear and is based on the AE generated due to elastic contact. Current studies in friction-generated acoustics have shown

23、 that the acoustic signals contain information relating to the material parameters of the friction pair. The work in this study uses the acoustic signal as a tool to characterise the material properties of the friction pair. The idea for this study originates from a study by Hill [8] for Scientifics

24、, when it became apparent that monitoring the ultrasound generated by a drilling process process had potential for ground condition monitoring. The overall aim of this work is to develop a method of characterising geotechnical materials using a typical drilling process and monitoring the ultrasound

25、generated due to the interaction between the drill tip and the geotechnical material. 2. Experimental design A simplified drilling arrangement has been constructed where a rotating probe is used to maximise the friction at the probe-tip–granular contact. The probe string is designed, using a suit

26、able coupling device, so that the ultrasonic signal is transmitted from the probe tip to a stationary piezoelectric sensor. The signal is amplified by 60 dB and filtered between 250 and 500 kHz. The captured signal is therefore in the mid-ultrasonic range and relates to the transducer monitoring fre

27、quency used. A schematic diagram of the experimental arrangement can be seen in Fig. 1. The probe rotates, while being submerged in a granular medium of controlled particle size, initial density and water content. The feed rate and angular velocity were set to a constant value and the applied load,

28、count rate and ultrasonic energy were simultaneously monitored. The effects of the particle size, density and water content on two ultrasonic parameters (count rate and energy) have been investigated and the system aims to be a future option for ground condition monitoring. 3. Results The effect o

29、f load on the count rate can be seen in Fig. 2a. The signal values on the left of the figure correspond to the probe tip not being in contact with the granular medium. When the probe is pushed into the granular material the load increases. The data highlights a stabilizatio(reduction) in the count r

30、ate and is referred to as the ‘‘characteristic count rate’’ for a particular friction pair. The stabilisation of the count rate means that no more oscillations are being produced due to an increase in the load and therefore the signal amplitude is only subject to amplitude increase. Different grades

31、 of particulate material have been used and the characteristic count rate monitored. The results indicate that a lower characteristic count rate occurs as the average particle size is increased. Eight samples of sand were used and the characteristic count rate is compared with the particle size in F

32、ig. 2b. Larger particle sizes produce fewer contacts and therefore the results agree with the assumption stated by Baranov et al. [6] that, the rate of counting is proportional to the number of contacts formed per unit time. The results in Fig. 2c reveal that the water content has little effect on t

33、he characteristic count rate. Four ranges of grain size have been used and the count rate is plotted against the mass percentage water content. There is a small variation in the count rate but the separation in the signals generated by the different particle sizes still exist. Results have revealed

34、 that the count rate value does not significantly change due to the addition of water and that the count ratesignal is mainly dependent on the number of contacts formed. Therefore, regardless of the water content of the sand it is possible to obtain an approximate evaluation of the average particle

35、size. The ultrasonic signal energy appears to be sensitive to a number of parameters including the particle size, water content, density and mineralogy. Fig. 3a shows the ultrasonic energy signal plotted against the applied force for two different initial dry densities (compacted and loose). Result

36、s indicate that the energy varies linearly with the applied load and the gradient increases with a reduction in the initial density. The effect of varying the density is more apparent when using smaller grain sizes. A change in the density using smaller particulate material will produce a larger aff

37、ect on the number of probe– granular contacts generated within the apparent contact area. Lower particulate densities produce fewer contacts and therefore the pressure due to the applied force is increased and may account for an increase in the average energy per oscillation as a function of the app

38、lied force. It is expected that an increase in the particulate size would also produce an increase in the acoustic energy as a result of higher contact pressures. Fig. 3b shows the change in the average energy per oscillation due to the applied force against the average particle diameter. Results in

39、dicate that there is no unique relationship between this ultrasonic energy parameter and the particle size, with a peak occurring at 512 lm. The effect of increasing the water content of the granular sample causes the sand to become acoustically quieter (a significant drop in signal amplitude). Al

40、though the sand becomes quieter, the rate of change of the ultrasonic energy due to the applied force is not affected by varying the level of water content in a wet sample but there is a noticeable difference in the gradient when comparing a dry sample with a wet sample. 4. Conclusions Results hav

41、e shown that when probing into granular materials, using a constant sliding velocity the count rate becomes stable (characteristic count rate). The characteristic count rate is affected by a change in the number probe–granular contacts and therefore provides a method for characterising the particle

42、size. The water content of a granular sample has little effect on the characteristic count rate and data agrees with the assumption stated by Baranov et al. [6] that the count rate is proportional to the number of contacts formed per unit time. However, the data does not agree with the general rule

43、suggested by Sarychev and Shchavelin [5], as the characteristic count rate does not depend on the applied force. Results provide positive evidence that monitoring the characteristic count rate has potential as a tool for identifying the layers of different particle size in ground structures regardle

44、ss of the moisture content. The ultrasonic energy signal is sensitive to a variety of parameters including the load, sliding velocity, particle size, density, water content and mineralogy. Results have indicated that the contact pressure, which is affected by altering the density and particle size,

45、 affects the acoustic energy signal. However, a continuous increase in the ultrasonic energy due to larger particle sizes, which was expected, did not occur. It is possible that larger particles produce larger particle-probe contact areas thus reducing the contact pressure at a single contact spot b

46、ut further work is needed for this to be established. It is clear that the ultrasonic energy contains information relating to the parameters of the friction pair but further investigation is required to fully understand the contribution of each parameter associated with the generated acoustic signal

47、. References [1] T.J. Holroyd, N. Randall, Use of acoustic emission for machine condition monitoring, Condition Monitoring 35 (2) (1993) 75–79. [2] S.T.S. Bukkapatnam, S.R.T. Kumara, A. Lakhtakia, Analysis of acoustic emission signals in machining, ASME Journal of Manufacturing Science and Engi

48、neering (1999) 183–207. [3] E.N. Diei, Acoustic emission sensing of tool wear in face milling, Journal of Engineering for Industry 109 (1987) 234–240. [4] C.L. Jiaa, D.A. Dornfield, Experimental studies of sliding friction and wear via acoustic emission signal analysis, Wear 139 (1990) 403–424. [

49、5] G.A. Sarychev, V.M. Shchavelin, Acoustic emission method for research and control of friction pairs, Tribology International 24 (1) (1991) 11–16. [6] V.M. Baranov, E.M. Kudryavtsev, G.A. Sarychev, Calculation of the parameters of acoustic emission when there is external friction between solids,

50、Russian Journal of Non-Destructive Testing 8 (1995) 569–577. [7] C. Henrique, M.A. Aguirre, A. Calvo, I. Ippolito, D. Bideau, Experimental acoustic technique in granular flows, Powder Technology94 (1997) 85–89. [8] R. Hill, Confidential consultancy Report, Scientifics, 1997. 附件2：

51、 巖土材料的摩擦聲波 摘要 鉆井作業(yè)涉及到設(shè)備生產(chǎn)，對(duì)于工程師來(lái)說(shuō)，還包括地址的選擇。鉆井通常要求高效地去除材料。在這項(xiàng)研究中，鉆井過(guò)程中摩擦副的相互作用提供了被鉆削巖土材料相關(guān)參數(shù)的超聲信息，在這些信息中鉆頭具有非降解的超聲特性，對(duì)于材料去除沒(méi)有基本的要求。這項(xiàng)研究認(rèn)為監(jiān)測(cè)鉆井過(guò)程中產(chǎn)生的超聲波信號(hào)，為表征巖土材料鉆削參數(shù)提供了新的觀(guān)點(diǎn)，并提供了一種識(shí)別或表征地面結(jié)構(gòu)的新方法。巖土材料系統(tǒng)的鉆削，通常涉及一個(gè)旋轉(zhuǎn)探頭和顆粒復(fù)合介質(zhì)的相互作用。測(cè)量旋轉(zhuǎn)探頭的載荷和角速度可用來(lái)確定它們和超聲信號(hào)的相關(guān)性。顆粒材料的樣本已經(jīng)把粒徑控制在一定范圍內(nèi)。精力主要集中在確定晶粒尺寸、堆積密度和顆粒材

52、料的含水量對(duì)超聲信號(hào)的影響。將不同粒徑、密度、水分含量和相關(guān)超聲波信號(hào)的顆粒樣本進(jìn)行比較，解釋每個(gè)變量的影響和有關(guān)這種影響的現(xiàn)有理論。這項(xiàng)研究一般的目的是評(píng)估鉆井的超聲監(jiān)測(cè)，并估計(jì)其在巖土地表實(shí)時(shí)狀態(tài)監(jiān)測(cè)中的應(yīng)用潛力，用它來(lái)代替現(xiàn)有的一些方法。 1.引言 固體–固體摩擦副產(chǎn)生的超聲波是摩擦產(chǎn)生超聲波研究的重點(diǎn)，主要涉及旋轉(zhuǎn)和往復(fù)運(yùn)動(dòng)的機(jī)械。相互接觸的材料相對(duì)運(yùn)動(dòng)過(guò)程中的摩擦產(chǎn)生固有的磨損，最終會(huì)導(dǎo)致工作故障。監(jiān)測(cè)機(jī)械產(chǎn)生的超聲波信號(hào)已成為一種不可替代的機(jī)器狀態(tài)監(jiān)測(cè)方法，因?yàn)槌暡ㄐ盘?hào)包含了與摩擦副的微觀(guān)環(huán)境相關(guān)的信息。當(dāng)機(jī)器零件發(fā)生磨損時(shí)，用這種方法來(lái)查明故障是可行的，因而降低了因?yàn)?zāi)難性故

53、障導(dǎo)致生產(chǎn)停機(jī)所帶來(lái)的風(fēng)險(xiǎn)。Holroyd和 Randall [ 1 ]論述了利用聲音輻射技術(shù)（AE）檢測(cè)潤(rùn)滑、超載、磨損變化的靈敏度問(wèn)題，并查閱了許多其他用于分析聲學(xué)特征的技術(shù)。Bukkapatnam等人[ 2 ]論述了用于分析摩擦聲信號(hào)更先進(jìn)的方法，并提出了一種基于混沌理論、小波和神經(jīng)網(wǎng)絡(luò)的新的分析技術(shù)。大多數(shù)有關(guān)狀態(tài)監(jiān)測(cè)的研究更關(guān)注由磨損引起的聲信號(hào)變化，而一些研究也已經(jīng)注意到與產(chǎn)生聲信號(hào)相關(guān)的參數(shù)。Diei [3]監(jiān)測(cè)了表面磨削過(guò)程中刀具磨損所產(chǎn)生的聲音輻射，提出了AERMS電壓和摩擦能量耗散率之間的冪函數(shù)關(guān)系 ekgssAaV Tm=2 e1T 。其中k和m取決于聲音輻射測(cè)量系統(tǒng)和

54、摩擦副材料性能常數(shù)；g是摩擦副的表面粗糙度和彈性度的函數(shù)；ss是界面材料的剪切強(qiáng)度；Aa是有效接觸面積，V是滑動(dòng)速率。參數(shù)g和Aa基本決定了有效接觸面積，因此AERMS是有效接觸面積、抗剪強(qiáng)度和滑動(dòng)速率的函數(shù)。Diei研究的結(jié)果也表明AERMS和滑動(dòng)速率線(xiàn)性相關(guān)。Jiaa and Dornfield [ 4 ]監(jiān)測(cè)了大頭針在磁盤(pán)上所產(chǎn)生的聲音輻射，表明聲音輻射是由于微凸體碰撞和粘滑現(xiàn)象所激發(fā)的微振動(dòng)產(chǎn)生脈沖沖擊引起的。 這項(xiàng)研究表明當(dāng)表面相對(duì)速度和AERMS之間存在線(xiàn)性關(guān)系時(shí)，AERMS隨負(fù)荷增加而增加。Sarychev and Shchavelin [5]描述了摩擦過(guò)程及其產(chǎn)生的聲音輻射，建

55、立了兩條與摩擦副滑動(dòng)速度及因加載產(chǎn)生的聲脈沖計(jì)數(shù)速率（計(jì)數(shù)率）相關(guān)的基本原則。計(jì)數(shù)率N_對(duì)滑動(dòng)速率依賴(lài)性的基本原則的形式是： N_ A t BvX e2T 。其中，A和B是常數(shù)，X取P1。同樣的關(guān)系也適用于載荷對(duì)于計(jì)數(shù)率的依賴(lài)性，只是指數(shù)X取61。進(jìn)一步把聲音輻射活躍度與彈性接觸產(chǎn)生摩擦的機(jī)理聯(lián)系起來(lái)，其關(guān)系表示為：N_ a k N0:71h0:71A0:71 c r0:90R1:60 a V e3T 。其中，N是正常負(fù)荷量，h是廣義彈性模量，Ac表示非接觸區(qū)的面積，r為表面粗糙度的尖端半徑，Ra是表面粗糙度，k為比例系數(shù)。Baranov[6] 做了進(jìn)一步的研究，給出了兩種模型：把摩擦副的

56、參數(shù)與聲音參數(shù)聯(lián)系起來(lái)；把計(jì)數(shù)率與聲音能量參數(shù)聯(lián)系起來(lái)。計(jì)數(shù)率模型是基于聲音脈沖計(jì)數(shù)率與單位時(shí)間內(nèi)所形成接觸點(diǎn)的數(shù)目成正比的假設(shè)。 Henrique等人[ 7 ]研究了粒子沿著斜坡向下碰撞，及用于檢測(cè)一個(gè)球滾下斜坡時(shí)產(chǎn)生碰撞（接觸）次數(shù)的聲音發(fā)生次數(shù)。聲音能量模型把一個(gè)接觸的微凸體彈性變形過(guò)程中產(chǎn)生的機(jī)械勢(shì)能與聲信號(hào)的振幅分布聯(lián)系起來(lái)。這種聲音能量模型沒(méi)有考慮磨損的影響，而且是基于彈性接觸產(chǎn)生的聲音輻射。 目前摩擦聲學(xué)研究已經(jīng)表明聲音信號(hào)包含了與摩擦副材料參數(shù)相關(guān)的信息。這項(xiàng)研究工作用聲信號(hào)作為一種表征摩擦副材料特性的工具。當(dāng)監(jiān)測(cè)鉆井過(guò)程中產(chǎn)生的超聲波對(duì)地面狀態(tài)監(jiān)測(cè)的作用變得明顯的時(shí)候，這種

57、思想在Hill[ 8 ]為Scientifics所做的一項(xiàng)研究中產(chǎn)生了。這項(xiàng)工作的總體目標(biāo)是研究一種利用典型鉆井過(guò)程并監(jiān)測(cè)鉆頭和巖土材料相互作用產(chǎn)生的超聲波來(lái)描述巖土材料特性的方法。 2. 實(shí)驗(yàn)設(shè)計(jì) 一個(gè)簡(jiǎn)單的鉆井裝置具有一個(gè)使探針–顆粒接觸面積最大化的旋轉(zhuǎn)探頭。使用合適的耦合裝置設(shè)計(jì)探頭串，使超聲波信號(hào)從探頭傳輸?shù)揭粋€(gè)固定的壓電傳感器。該信號(hào)被放大了60分貝并過(guò)濾掉250和500千赫之間的信號(hào)。因此所得到的信號(hào)在中超聲波的范圍內(nèi)并與所使用傳感器的監(jiān)測(cè)頻率有關(guān)。實(shí)驗(yàn)裝置示意圖如圖1所示。探頭伸入具有一定粒徑、初始密度和含水量的顆粒介質(zhì)中旋轉(zhuǎn)。探頭的進(jìn)給速度和角速度設(shè)置為一定值，并同時(shí)監(jiān)測(cè)所

58、施加的載荷、計(jì)數(shù)率和超聲波能量。粒徑、密度和含水量對(duì)兩種超聲參數(shù)（計(jì)數(shù)率和能量）的影響被進(jìn)行了研究，這種研究的目的是為未來(lái)地面狀態(tài)監(jiān)測(cè)提供一種選擇。 3. 實(shí)驗(yàn)結(jié)果 載荷對(duì)于計(jì)數(shù)率的影響如圖2a所示。位于圖左側(cè)的信號(hào)數(shù)值對(duì)應(yīng)不與顆粒介質(zhì)接觸的探針。當(dāng)探頭推入顆粒材料時(shí)，負(fù)載隨之增加。對(duì)于計(jì)數(shù)率模型，所得數(shù)據(jù)要求穩(wěn)定可靠（原始），并將之稱(chēng)為一個(gè)特定摩擦副的“特征計(jì)數(shù)率”。計(jì)數(shù)率的穩(wěn)定意味著負(fù)載的增加不會(huì)產(chǎn)生更多的震蕩，因此信號(hào)幅度只受振幅增加的影響。實(shí)驗(yàn)中使用了不同等級(jí)的顆粒材料，并且其特征計(jì)數(shù)率也已被監(jiān)測(cè)。 研究結(jié)果表明，隨著平均粒徑的增大特征計(jì)數(shù)率會(huì)降低。在圖2b中，對(duì)八份沙子樣本進(jìn)行了

59、特征計(jì)數(shù)率與粒徑的比較。粒徑越大，接觸面積就越小。因此實(shí)驗(yàn)結(jié)果印證了Baranov等人[ 6 ]提出的計(jì)數(shù)率與單位時(shí)間內(nèi)接觸次數(shù)成正比的假設(shè)。在圖2c中，實(shí)驗(yàn)結(jié)果表明含水量對(duì)特征計(jì)數(shù)率影響不大。使用四種不同尺寸的晶粒，畫(huà)出計(jì)數(shù)率與質(zhì)量含水率的關(guān)系曲線(xiàn)。盡管計(jì)數(shù)率發(fā)生很小的變化，但是不同粒徑產(chǎn)生的信號(hào)分離仍然存在。實(shí)驗(yàn)結(jié)果表明，增加水含量不會(huì)引起計(jì)數(shù)率地顯著變化，計(jì)數(shù)率信號(hào)主要取決于產(chǎn)生接觸的次數(shù)。因此，無(wú)論沙子含水量多少，都可以獲得其平均粒度的近似計(jì)算。 超聲波信號(hào)的能量似乎對(duì)包括顆粒大小、含水量、密度和礦物質(zhì)含量在內(nèi)的一些參數(shù)很敏感。圖3a顯示出超聲波能量信號(hào)與施加在兩份不同初始干密度（松

60、散與密實(shí)）樣本上的力的關(guān)系曲線(xiàn)。實(shí)驗(yàn)結(jié)果表明，超聲波信號(hào)的能量與施加的荷載線(xiàn)性相關(guān)，相關(guān)線(xiàn)的斜率隨樣本初始密度的降低而增加。當(dāng)使用較小的晶粒尺寸時(shí)，密度變化對(duì)超聲波信號(hào)能量的影響更為顯著。使用粒徑更小的顆粒材料時(shí)，密度的變化將對(duì)表面接觸區(qū)中探針–顆粒接觸次數(shù)產(chǎn)生更大的影響。較低的顆粒密度產(chǎn)生更少的接觸，因而荷載產(chǎn)生的壓力增大，并可能使荷載的函數(shù)——平均每振蕩的能量增加。預(yù)計(jì)由于較高的接觸壓力顆粒尺寸的增加也會(huì)使超聲波能量增加。圖3b顯示了由于對(duì)平均粒徑施加力而引起平均每振蕩能量的變化。結(jié)果表明在粒徑達(dá)到512 lm時(shí)超聲波能量參數(shù)和粒徑之間沒(méi)有特殊的關(guān)系。 增加顆粒樣本的含水量導(dǎo)致沙子

61、變得更安靜（聲信號(hào)幅值顯著下降）。雖然沙子變得更安靜，在潮濕的沙子樣本中因施力產(chǎn)生的超聲波能量的變化率不受水含量變化的影響，但是當(dāng)把干燥的樣本與潮濕的樣本進(jìn)行比較時(shí)，它們?cè)诼暡ㄌ荻壬先杂忻黠@的差異。 4. 結(jié)論 實(shí)驗(yàn)結(jié)果表明，用一個(gè)恒定的滑動(dòng)速率探查顆粒材料時(shí)，計(jì)數(shù)率趨于穩(wěn)定（特征計(jì)數(shù)率）。特征計(jì)數(shù)率受到探針–顆粒接觸次數(shù)的影響，從而提供了一種用于表征顆粒粒徑的方法。顆粒樣本的含水量對(duì)特征計(jì)數(shù)率幾乎無(wú)影響。而且實(shí)驗(yàn)所得數(shù)據(jù)印證了Baranov等人[ 6 ]所提出的計(jì)數(shù)率與單位時(shí)間內(nèi)接觸次數(shù)成正比的假設(shè)。然而，實(shí)驗(yàn)所得數(shù)據(jù)不符合Sarychev和shchavelin [ 5 ]提出的

62、一般規(guī)律，因?yàn)樘卣饔?jì)數(shù)率不依賴(lài)于所施加的力。實(shí)驗(yàn)結(jié)果提供了有力的證據(jù)來(lái)表明監(jiān)測(cè)特征計(jì)數(shù)率具有實(shí)現(xiàn)不依賴(lài)水分含量而識(shí)別地面結(jié)構(gòu)不同粒度層的潛力。 超聲波能量信號(hào)對(duì)于包括負(fù)載、滑動(dòng)速率、粒徑、密度、含水量和礦物質(zhì)含量在內(nèi)的多種參數(shù)很敏感。實(shí)驗(yàn)結(jié)果表明受密度和粒徑變化影響的接觸壓力會(huì)影響聲波能量信號(hào)。然而，在意料之中，由于更大的顆粒尺寸而引起超聲波能量持續(xù)地增加不會(huì)發(fā)生。較大的顆粒產(chǎn)生較大的粒子-探頭接觸面積從而減小單一接觸點(diǎn)的接觸壓力是可能的，但需進(jìn)一步研究來(lái)支持這種觀(guān)點(diǎn)。很明顯，超聲波能量包含了與摩擦副參數(shù)相關(guān)的信息，但是為了完全了解與產(chǎn)生聲音信號(hào)相關(guān)的每個(gè)參數(shù)的分布，還需要做進(jìn)一步的研究。

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