【摘要】：開縫鋼板剪力墻、開孔鋼板剪力墻、圓孔蜂窩梁、梁腹板開圓孔節(jié)點、節(jié)點焊接處等,都存在復雜應變場。鋼結構中這些復雜應變區(qū)域存在同向的二維或者三維應變場以及低溫環(huán)境往往導致鋼材脆化、造成鋼結構脆性破壞。因此復雜應變場的產(chǎn)生機理有重要的研究意義。復雜應變場的研究有很多,并形成了許多的理論方法。然而,只有少量的邊界條件和幾何形狀相對簡單的情形能夠得到彈性力學的解析解；更多的情況下需要用有限元法近似求解；而對于更復雜的情況往往就只能借助實驗方法了。事實上結構的實驗分析方法非常重要：既可以對解析解進行驗證,還可以解決很多理論方法不能解決的復雜實際問題。本文研究復雜應變場測量實驗方法,并且通過基于重疊貼片法的復雜應變場電測實驗驗證本文方法的可行性。主要內容如下：1、歸納、總結常規(guī)電阻應變測量技術,討論基于重疊貼片的電測法測量復雜應變場的基本原理和測量方法。通過三個不同柵長的應變片重疊的方法得到點應變值,然后利用獲得的應變實測值通過牛頓插值擬合某個軸上的復雜應變場；模擬分析發(fā)現(xiàn)：對復雜應變場中的一點,通過重疊粘貼多個不同柵長應變片的方法比單片粘貼應變片測量方法能更加準確地反映出被測點的應變值。而對于在測點區(qū)間外的測點(即外推的數(shù)據(jù))誤差較大。所以,通過構造牛頓插值多項式函數(shù)的應變場測量方法需要進行改進。2、在重疊三片貼片法的基礎上,模擬分析重疊四片和五片不同柵長應變片的測量方法。得出了重疊粘貼四片應變片測量效果最為理想的結論。3、提出一種關于復雜應變場測量的基于重疊貼片的雙三次樣條插值曲面擬合方法。即通過重疊貼片的電測法得到復雜應變場區(qū)域的點應變值,再通過雙三次樣條插值的曲面擬合方法得到復雜應變區(qū)域的應變場。本文結果表明：通過重疊應變片測量的方法得到獲得測點處高精度的應變實測值,再利用雙三次樣條插擬合應變場較最小二乘擬合的曲面場相對誤差小、效果更理想。4、以一典型的帶孔拉伸板為實驗對象,獲得重疊貼片的實測數(shù)據(jù)；分別進行最小二乘擬合與雙三次樣條插值曲面擬合求解應變場；最后對ANSYS結果、實測數(shù)據(jù)、牛頓插值結果、最小二乘擬合與雙三次樣條插值曲面擬合以及數(shù)字圖像相關分析方法實測結果等進行綜合分析比較。本文關于復雜應變場測量的基于重疊貼片和雙三次樣條插值曲面擬合方法應變電測方法精度高、是有效實用的。
[Abstract]:The complex strain field exists in the slotted steel plate shear wall, the perforated steel plate shear wall, the circular honeycomb beam, the web opening joint of the beam, the joint welding, and so on. In these complex strain regions of steel structures there are two or three dimensional strain fields in the same direction and the low temperature environment often leads to steel embrittlement resulting in brittle failure of steel structures. Therefore, the mechanism of complex strain field is of great significance. There are many researches on complex strain field, and many theoretical methods have been formed. However, only a small number of boundary conditions and relatively simple geometric shapes can obtain the analytical solution of elastic mechanics; in more cases, it is necessary to use the finite element method to approximate solution; but for more complex cases, it is often only by means of experimental methods. In fact, the experimental analysis method of the structure is very important: it can not only verify the analytical solution, but also solve many complex practical problems which can not be solved by the theoretical method. In this paper, the experimental method of measuring complex strain field is studied, and the feasibility of this method is verified by electrical measurement of complex strain field based on overlap patch method. The main contents are as follows: 1. The basic principle and method of measuring complex strain field by electrical measurement based on overlapped patch are discussed. The point strain values are obtained by the method of overlapping strain gauges with three different gate lengths, and the complex strain field on an axis is fitted by Newton interpolation. The simulation results show that the strain values of the measured points can be more accurately reflected by the method of overlapping multiple strain gauges with different gate lengths than by the method of single piece sticking strain gauges for a point in a complex strain field. However, the error of measuring points (i.e. extrapolated data) outside the interval is large. Therefore, it is necessary to improve the method of strain field measurement by constructing Newton interpolation polynomial function. 2. Based on the method of overlapping three patches, the measurement method of overlapping four pieces and five pieces of strain gauges with different gate lengths is simulated and analyzed. It is concluded that the effect of overlapping paste four pieces of strain gauges is the most ideal. 3. A fitting method of double cubic spline interpolation surface based on overlapping patches is proposed for complex strain field measurement. The point strain of the complex strain field is obtained by the electrical measurement of the overlapped patch, and the strain field of the complex strain region is obtained by the surface fitting method of the double cubic spline interpolation. In this paper, the results show that the high precision strain measurements are obtained by the method of overlapping strain gauges, and the bicubic spline interpolation is used to fit the strain field with less relative error than the surface field fitted by the least square method. 4. Taking a typical stretching plate with holes as the experimental object, the measured data of the overlapped patch were obtained. The strain field is solved by least square fitting and bicubic spline interpolation respectively. Finally, the ANSYS results, the measured data, the Newton interpolation results, the least square fitting, the bicubic spline interpolation surface fitting and the digital image correlation analysis results are comprehensively analyzed and compared. In this paper, the method based on overlapped patch and bicubic spline interpolation surface fitting method for measuring complex strain field has high accuracy and is effective and practical.
【學位授予單位】：長沙理工大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：TU317
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本文編號：2338841