發(fā)布時(shí)間：2018-05-17 00:01

  本文選題：斷裂行為 + 斷裂準(zhǔn)則　； 參考：《南京理工大學(xué)》2015年碩士論文

【摘要】：隨著固體火箭發(fā)動(dòng)機(jī)朝大口徑、遠(yuǎn)射程的方向發(fā)展,具有粘彈力學(xué)特征的改性雙基推進(jìn)劑表現(xiàn)出越來(lái)越明顯的率相關(guān)性,尤其是在高點(diǎn)火沖擊、高發(fā)射過(guò)載、跌落撞擊等沖擊載荷下,其力學(xué)性能完全區(qū)別于準(zhǔn)靜態(tài)條件。本文針對(duì)這種情況,使用脆性材料力學(xué)理論對(duì)改性雙基推進(jìn)劑斷裂力學(xué)行為進(jìn)行了研究。本文使用分離式霍普金森壓桿(SHPB)和萬(wàn)能材料試驗(yàn)機(jī)對(duì)改性雙基推進(jìn)劑的I型和II型斷裂行為進(jìn)行了實(shí)驗(yàn)研究。I型斷裂主要進(jìn)行了10-4～101s-1應(yīng)變率下的單軸拉伸斷裂實(shí)驗(yàn),得到了平面應(yīng)力、應(yīng)力集中對(duì)斷裂性能的影響及斷裂能在準(zhǔn)靜態(tài)條件下隨應(yīng)變率的變化規(guī)律。II型斷裂研究使用剪切試件進(jìn)行102-103s-1應(yīng)變率下的高速撞擊實(shí)驗(yàn),得到了改性雙基推進(jìn)劑高應(yīng)變率下的斷裂行為判定準(zhǔn)則；并補(bǔ)充以104～101s-1應(yīng)變率下的剪切試件壓縮實(shí)驗(yàn)作為對(duì)比。通過(guò)實(shí)驗(yàn)結(jié)果比較可知,改性雙基推進(jìn)劑在高應(yīng)變下表現(xiàn)出脆性斷裂現(xiàn)象,而準(zhǔn)靜態(tài)環(huán)境中只有在大變形下才會(huì)發(fā)生斷裂,即應(yīng)變率對(duì)材料斷裂形式影響很大。高應(yīng)變率下,斷裂能與應(yīng)變率呈線(xiàn)性相關(guān)；準(zhǔn)靜態(tài)下,斷裂能與應(yīng)變率呈指數(shù)相關(guān)。同時(shí),本文還使用分離式霍普金森壓桿對(duì)改性雙基推進(jìn)劑的本構(gòu)進(jìn)行了研究,得到了可以準(zhǔn)確描述該材料在高應(yīng)變率下力學(xué)行為的線(xiàn)性ZWT本構(gòu)模型。為了將上述實(shí)驗(yàn)結(jié)果用于改性雙基推進(jìn)劑工程預(yù)測(cè)數(shù)值計(jì)算,采用FORTRAN語(yǔ)言對(duì)材料的本構(gòu)模型和斷裂行為判定準(zhǔn)則進(jìn)行了VUMAT程序?qū)崿F(xiàn)。最后使用ABAQUS對(duì)圓柱形試件和II型剪切試件進(jìn)行數(shù)值計(jì)算驗(yàn)證,以確定材料的本構(gòu)與斷裂行為判定準(zhǔn)則的正確性。
[Abstract]:With the development of solid rocket motor in the direction of large caliber and long range, modified double base propellants with viscoelastic mechanical characteristics show more and more obvious rate correlation, especially in high ignition impact and high emission overload. Under the impact load such as drop impact, the mechanical properties are completely different from the quasi static condition. In this paper, the fracture mechanics behavior of modified double base propellants is studied by using the theory of brittle material mechanics. In this paper, the mode I and mode II fracture behaviors of modified double-base propellants have been experimentally studied by using split Hopkinson compression bar (SHPB) and universal material testing machine. The uniaxial tensile fracture tests of type I propellants at 10-4~101s-1 strain rate have been carried out. The effects of plane stress and stress concentration on fracture properties and the variation of fracture energy with strain rate under quasi-static conditions are obtained. The criterion of fracture behavior of modified double base propellant at high strain rate is obtained, and the compression test of shear specimen at 104~101s-1 strain rate is added as a comparison. The experimental results show that the modified double base propellants exhibit brittle fracture under high strain, but only under large deformation in quasi static environment, that is, the strain rate has a great influence on the fracture form of the material. At high strain rate, the fracture energy is linearly correlated with strain rate, and the fracture energy is exponentially correlated with strain rate under quasi-static condition. At the same time, the constitutive model of modified double base propellant was studied by using split Hopkinson pressure bar, and a linear ZWT constitutive model was obtained to describe the mechanical behavior of the material at high strain rate. In order to apply the above experimental results to the engineering prediction numerical calculation of modified double-base propellants, the constitutive model of the material and the criterion of fracture behavior were realized by VUMAT program using FORTRAN language. Finally, the numerical calculation of cylindrical and type II shear specimens is carried out with ABAQUS to determine the correctness of the constitutive and fracture behavior criteria of the material.
【學(xué)位授予單位】：南京理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類(lèi)號(hào)】：V512

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本文編號(hào)：1898983