本文選題：超聲相控陣 + Nios��； 參考：《天津大學(xué)》2014年碩士論文

【摘要】：超聲相控陣技術(shù)因其掃查速度快、聲束控制靈活、檢測靈敏度高、適用范圍廣等多項優(yōu)點而被推廣使用,并逐漸成為國際無損檢測領(lǐng)域研究熱點。本文以相控陣超聲缺陷檢測信號處理相關(guān)技術(shù)為主線,先從硬件和軟件方面實現(xiàn)超聲信號的獲取,為自主研發(fā)超聲相控陣設(shè)備奠定了基礎(chǔ);緊接著對缺陷信號的處理方法進行了研究和實驗驗證,最后將分形技術(shù)應(yīng)用于提取近表面缺陷信號特征并實現(xiàn)缺陷識別。相控陣超聲缺陷檢測中首先要實現(xiàn)的是聲波的相控發(fā)射與接收,本文建立了帶楔塊超聲相控陣檢測的聲束偏轉(zhuǎn)和聲束聚焦模型,并計算兩種模型的延遲法則,通過仿真說明了延遲法則相控技術(shù)對聲束合成的影響,分析了超聲相控陣缺陷檢測的成像方法。為實現(xiàn)缺陷信號的獲取,提出了基于FPGA嵌入式處理器的超聲信號采集方案,通過在FPGA內(nèi)部構(gòu)建以Nios Ⅱ軟核為處理器的片上可編程系統(tǒng)(SOPC,System On a Programmable Chip),實現(xiàn)對超聲信號采集A/D芯片以及信號傳輸USB芯片的控制,構(gòu)建了嵌入式超聲信號采集平臺。針對全矩陣捕獲(FMC,Full Matrix Capture)這一獲取缺陷全面信息的掃查方式,對Multi2000系統(tǒng)進行軟件開發(fā)以獲取全矩陣數(shù)據(jù),提出了運用全聚焦成像算法(TFM,Total Focusing Methods)對全矩陣數(shù)據(jù)進行后處理。為排除實驗外界干擾對算法驗證的影響,仿真了全矩陣捕獲過程。對獲得的仿真和實驗數(shù)據(jù)分別用平面B掃、聚焦B掃和TFM的成像方法處理,結(jié)果表明,全聚焦成像的方法有助于提高缺陷成像分辨率。最后本文針對工業(yè)相控陣超聲缺陷檢測過程中近表面缺陷的漏檢問題,提出運用分形理論的方法對實驗獲得的A-Scan缺陷信號進行處理,計算其盒計數(shù)維數(shù),通過統(tǒng)計分析證明了分形理論可應(yīng)用于近表面缺陷A-Scan信號處理,盒維數(shù)特征可用于識別近表面缺陷。
[Abstract]:Ultrasonic phased array technology has been widely used because of its advantages of fast scanning speed, flexible control of sound beam, high detection sensitivity, wide range of application and so on, and has gradually become a hot spot in the field of international nondestructive testing (NDT). In this paper, the ultrasonic signal processing technology of phased array ultrasonic defect detection is the main line, first from the hardware and software to achieve ultrasonic signal acquisition, for the development of ultrasonic phased array equipment laid the foundation; Then, the processing method of defect signal is studied and verified by experiments. Finally, fractal technique is applied to extract the feature of near-surface defect signal and to realize defect recognition. The first thing to be realized in the ultrasonic defect detection of phased array is to transmit and receive the sound wave. In this paper, the acoustic beam deflection and the focusing model of ultrasonic phased array with wedge are established, and the delay rules of the two models are calculated. The effect of delay rule phase control technology on acoustic beam synthesis is illustrated by simulation, and the imaging method of ultrasonic phased array defect detection is analyzed. In order to obtain defect signal, an ultrasonic signal acquisition scheme based on FPGA embedded processor is proposed. An embedded ultrasonic signal acquisition platform is constructed by constructing a programmable system on a Programmable ChipP with Nios 鈪，

本文編號：2002364