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  本文關(guān)鍵詞： 光滑粒子法 FE-SPH耦合算法 應(yīng)力波 鋼纖維混凝土 應(yīng)變率效應(yīng) 損傷軟化效應(yīng) 侵徹　出處：《中國科學(xué)技術(shù)大學(xué)》2017年博士論文　論文類型：學(xué)位論文

【摘要】：作為一種粒子類方法,光滑粒子法在沖擊動力學(xué)問題的計算中具有其特定的優(yōu)勢,比如它很適合進行大變形、斷裂和破碎的處理,并且可以很方便的追蹤物質(zhì)界面等。本文在介紹光滑粒子法一般理論的基礎(chǔ)上,研究了核函數(shù)和光滑長度在應(yīng)力波的光滑粒子法模擬中的作用,并采用光滑粒子法完成了對材料層裂的數(shù)值模擬。相對素混凝土,鋼纖維混凝土具有更高的強度和韌性,適用于軍事防護工程和民事建筑,本文對鋼纖維混凝土的動態(tài)力學(xué)性能進行了深入研究,重點在于應(yīng)變率、損傷和鋼纖維含量對混凝土的強度和韌性的影響及其耦合作用,并給出了相應(yīng)的本構(gòu)模型。FE-SPH耦合方法結(jié)合了光滑粒子法和有限元法的優(yōu)勢,同時具有較高的效率和精度,非常適用于侵徹等沖擊動力學(xué)問題的模擬,本文深入研究了 FE-SPH耦合算法,重點在于單元-粒子接觸算法,并采用二維軸對稱FE-SPH耦合程序?qū)︿摾w維混凝土侵徹問題進行了數(shù)值模擬,驗證了耦合算法的可靠性,并研究了鋼纖維混凝土的抗侵徹機理。本文的研究內(nèi)容和創(chuàng)新成果主要包括:本文第2章闡述了光滑粒子法的基本思想,介紹了光滑粒子法中核近似和粒子近似的基本概念。將連續(xù)介質(zhì)力學(xué)守恒方程在直角笛卡爾坐標(biāo)系下進行了光滑粒子離散,研究了利用光滑粒子方法進行連續(xù)介質(zhì)動力學(xué)問題計算需要考慮的一些基本問題,包括CFL條件、核函數(shù)、可變光滑長度、粒子搜索方法和本構(gòu)嵌入等。最后引入改進的光滑粒子方法(CSPM),說明了其優(yōu)越性。在第3章中將通量修正輸運法引入光滑粒子法以進行間斷面的處理,并對通量修正輸運法與人工粘性法的處理效果進行了對比。研究了核函數(shù)和光滑長度對光滑粒子法模擬應(yīng)力波的影響,給出了適用于應(yīng)力波模擬的核函數(shù)和相應(yīng)光滑長度,并給出了一個代表模擬精度的參數(shù)。采用CSPM方法對45#鋼的層裂進行了模擬,以實驗結(jié)果為依據(jù),對比了 FDM和CSPM給出的自由面速度時程曲線,證明CSPM方法可以更好的模擬固體中的應(yīng)力波傳播和層裂問題。第4章首先對鋼纖維混凝土的霍普金森桿實驗技術(shù)進行了研究,重點研究了整形器的原理:減少入射波高頻部分,更好的維持恒應(yīng)變率加載和應(yīng)力均勻狀態(tài)。利用霍普金森桿研究了六種不同鋼纖維體積比混凝土的動態(tài)力學(xué)行為,分析了應(yīng)變率和鋼纖維體積比對混凝土強度、峰值應(yīng)變和能量耗散的影響,探討了應(yīng)變率效應(yīng)和鋼纖維增強效應(yīng)的機理。在分析總結(jié)了前人有關(guān)混凝土應(yīng)變率效應(yīng)方面成果的基礎(chǔ)上,提出了一個新的動態(tài)增強因子公式,并對動態(tài)增強因子公式嵌入本構(gòu)的方式進行了修正�；�于上述實驗和理論分析結(jié)果,提出了一個新的混凝土粘塑性損傷軟化本構(gòu)模型,此模型在物理上更加嚴(yán)謹(jǐn),在處理方法上更加簡潔明了,并且能夠很好的反映混凝土材料的應(yīng)變率效應(yīng)、應(yīng)變率突躍效應(yīng)、卸載非線性回滯效應(yīng)和損傷軟化效應(yīng)等各種力學(xué)行為;在對新本構(gòu)模型進行擬合的過程中,發(fā)展了一種逐步積分最小二乘法,并采用這種方法擬合出本構(gòu)關(guān)系和損傷演化方程的全部參數(shù),方法簡潔有效,適用于一切含損傷的材料本構(gòu)關(guān)系參數(shù)的確定。最后,第5章對有限元-光滑粒子耦合算法(FE-SPH)進行了研究和改進,重點是有限元單元-光滑粒子的轉(zhuǎn)化算法、有限元單元間的接觸算法、光滑粒子間的接觸算法和有限元單元-光滑粒子間的接觸算法�；�于本文對鋼纖維混凝土動態(tài)力學(xué)性能的研究成果,在二維軸對稱FE-SPH耦合程序中引入鋼纖維混凝土的本構(gòu)模型,對45#鋼彈體侵徹鋼纖維混凝土的過程進行了數(shù)值模擬;對比了實驗和數(shù)值計算得到的剩余速度,驗證了程序的有效性;給出了不同時刻的侵徹圖形,分析了鋼纖維混凝土的抗侵徹機理,認(rèn)為加入鋼纖維增強了混凝土的抗壓強度、抗拉強度和韌性,并可有效阻止材料損傷裂紋的擴展,這些因素都提高了鋼纖維混凝土的抗侵徹能力。
[Abstract]:As a kind of particle method, SPH method has its particular advantages in the calculation of impact dynamics problems, such as it is suitable for large deformation, fracture and fragmentation, and can easily track the material interface. Based on the general introduction of SPH theory, study the role of nuclear function and the smooth length in smoothed particle method to simulate the stress wave in, and by SPH method to complete the numerical simulation of spallation. Compared to plain concrete, steel fiber reinforced concrete has higher strength and toughness, suitable for military protection engineering and civil construction, the dynamic mechanical properties of steel fiber reinforced concrete conducted in-depth research, focuses on the influence of strain rate, and damage of steel fiber content on the strength and toughness of concrete and its coupling effect, and gives the corresponding constitutive model of.FE-SPH coupling method A combination of SPH method and finite element method, the efficiency and it has a high precision. The simulation is very suitable for dynamic problems of penetration impact, this paper studies the FE-SPH coupling algorithm, focuses on the unit - particle contact algorithm, and the two-dimensional axisymmetric FE-SPH coupling procedure to simulate the steel fiber reinforced concrete the penetration problem, verify the reliability of the coupling algorithm, the anti penetration mechanism of steel fiber reinforced concrete and research. In this paper, the research contents and innovations include: the second chapter elaborates the thought of SPH method, introduces the basic concepts of SPH method in approximation and continuum mechanics. The conservation equations in Cartesian coordinates of Descartes smooth particle discrete, studied the continuum dynamics calculation needs to consider the use of SPH method Some basic problems, including CFL, kernel function, smoothing length, particle search method and constitutive embedding. Finally the introduction of improved SPH method (CSPM), shows its superiority. The third chapter will be in flux corrected transport method is introduced into the SPH method for processing discontinuity, comparison and the treatment effect of the flux corrected transport method and artificial viscosity method. The kernel function and the smoothing length simulated the stress wave effect of SPH method, are given for the kernel function of stress wave simulation and the corresponding smooth length parameter is given a representative simulation accuracy by the method of CSPM. 45# steel layer crack was simulated on the basis of experimental results, comparing the free surface velocity of FDM and CSPM given time curve, simulation of solid proved that CSPM method can better the stress wave propagation and spall problems. The fourth chapter firstly Hopkinson test technology of steel fiber reinforced concrete is studied, focusing on the principle of pulse shaper: reduce the incident wave frequency components, to better maintain the constant strain rate loading and uniform stress state. Using the Hopkinson bar on six different steel fiber volume ratio of the dynamic mechanical behavior of concrete, strain rate and analysis the steel fiber volume ratio and concrete strength, peak strain and the effect of energy dissipation, discusses the mechanism of enhancement effect and strain rate effect of steel fiber are summarized. Based on the analysis of previous studies on the strain rate effect of concrete achievements, put forward a new dynamic enhancement factor formula, and the dynamic enhancement factor formula embedded constitutive the method is modified. The experimental and theoretical analysis based on the results, proposed a new concrete viscoplastic damage softening constitutive model, this model is physically more In the processing method is more rigorous, concise, and can well reflect the strain rate effect, strain rate effect, unloading nonlinear hysteresis effect and damage softening effect of various mechanical behavior; in the process of the new constitutive model were fitted in the development of an integral least square method. By fitting a constitutive relation and damage evolution equation of all parameters of this method, method is simple and effective, suitable for all materials with damage to determine the constitutive relation parameters. Finally, the fifth chapter of the finite element smoothed particle coupling algorithm (FE-SPH) is studied and improved, the focus is on finite element - transformation algorithm smooth particle contact algorithm, finite element contact between the smooth algorithm between particles and finite element - smooth inter particle contact algorithm. In this paper, the dynamic mechanical properties of steel fiber concrete based on The research results, the constitutive model of steel fiber reinforced concrete is introduced in the two-dimensional axisymmetric FE-SPH coupling in the program, the process of 45# steel projectile penetrating steel fiber concrete was simulated; the residual velocity is calculated by experimental and numerical comparison, verify the effectiveness of the program; given penetration graphics at different times. Analysis of the anti penetration mechanism of steel fiber reinforced concrete, adding that the steel fiber reinforced concrete compressive strength, tensile strength and toughness, and can effectively prevent the damage of crack propagation materials, these factors have increased the steel fiber concrete anti penetration ability.

【學(xué)位授予單位】：中國科學(xué)技術(shù)大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2017
【分類號】：TB12

【參考文獻】

相關(guān)期刊論文 前10條

1 張凱;陳榮剛;張威;姜錫權(quán);;混凝土動態(tài)直接拉伸實驗技術(shù)研究[J];實驗力學(xué);2014年01期

2 黃瑞源;李永池;章杰;高光發(fā);;壓剪耦合損傷演化方程在混凝土本構(gòu)模型中的應(yīng)用[J];北京理工大學(xué)學(xué)報;2013年06期

3 張志春;強洪夫;高巍然;;SPH-FEM接觸算法在沖擊動力學(xué)數(shù)值計算中的應(yīng)用[J];固體力學(xué)學(xué)報;2011年03期

4 張志春;強洪夫;高巍然;;一種新型SPH-FEM耦合算法及其在沖擊動力學(xué)問題中的應(yīng)用[J];爆炸與沖擊;2011年03期

5 田威;黨發(fā)寧;梁昕宇;陳厚群;;混凝土單軸壓縮下細(xì)觀損傷特性的CT研究[J];實驗力學(xué);2009年03期

6 強洪夫;王坤鵬;高巍然;;基于完全變光滑長度SPH方法的高能炸藥爆轟過程數(shù)值試驗[J];含能材料;2009年01期

7 胡秀章;劉永勝;王肖鈞;谷先廣;;超短鋼纖維混凝土抗侵徹性能的實驗研究[J];彈道學(xué)報;2008年02期

8 黨發(fā)寧;劉彥文;丁衛(wèi)華;陳厚群;;基于破損演化理論的混凝土CT圖像定量分析[J];巖石力學(xué)與工程學(xué)報;2007年08期

9 劉永勝;王肖鈞;金挺;勞俊;;鋼纖維混凝土力學(xué)性能和本構(gòu)關(guān)系研究[J];中國科學(xué)技術(shù)大學(xué)學(xué)報;2007年07期

10 李永池;曹結(jié)東;董杰;姚磊;;45~#鋼的損傷演化方程和層裂準(zhǔn)則研究[J];力學(xué)季刊;2006年02期

相關(guān)博士學(xué)位論文 前6條

1 章杰;應(yīng)力波傳播和噴發(fā)彈侵徹數(shù)值模擬中的SPH方法[D];中國科學(xué)技術(shù)大學(xué);2015年

2 卞梁;高速碰撞中的SPH方法及其應(yīng)用研究[D];中國科學(xué)技術(shù)大學(xué);2009年

3 王峰;有限元方法及其在高速碰撞中的應(yīng)用[D];中國科學(xué)技術(shù)大學(xué);2007年

4 劉永勝;鋼纖維混凝土力學(xué)性能和抗侵徹機理研究[D];中國科學(xué)技術(shù)大學(xué);2006年

5 王吉;光滑粒子法與有限元的耦合算法及其在沖擊動力學(xué)中的應(yīng)用[D];中國科學(xué)技術(shù)大學(xué);2006年

6 巫緒濤;鋼纖維高強混凝土動態(tài)力學(xué)性質(zhì)的研究[D];中國科學(xué)技術(shù)大學(xué);2006年

，

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