本文關(guān)鍵詞： 動(dòng)態(tài)破壞 混凝土 數(shù)值模擬 二級(jí)配 沖擊荷載　出處：《寧夏大學(xué)》2017年碩士論文　論文類(lèi)型：學(xué)位論文

【摘要】：混凝土是民用、工業(yè)、安全防護(hù)等建筑中應(yīng)用最普遍的材料之一,有抗壓強(qiáng)度高、工藝簡(jiǎn)單、抗腐蝕性好、抗耐性?xún)?yōu)良等特點(diǎn)。混凝土結(jié)構(gòu)在應(yīng)用階段不僅要考慮緩慢變化準(zhǔn)靜態(tài)荷載,同時(shí)還需考慮抗沖擊、抗爆炸等動(dòng)荷載作用,因此有必要進(jìn)行混凝土動(dòng)態(tài)特性研究。從宏觀(guān)上看,混凝土是各向同性材料,但從微觀(guān)上看,混凝土是由粗骨料和水泥砂漿兩者構(gòu)成的復(fù)合材料。本文運(yùn)用ANSYS/LS-DYNA軟件對(duì)2個(gè)模型尺寸二級(jí)配混凝土動(dòng)態(tài)力學(xué)性能進(jìn)行了有限元分析,具體研究?jī)?nèi)容如下:(1)粗骨料的投放,先利用富勒級(jí)配曲線(xiàn)及瓦拉文平面轉(zhuǎn)化公式將三維空間問(wèn)題轉(zhuǎn)化為二維平面問(wèn)題,即利用瓦拉文平面轉(zhuǎn)化公式計(jì)算出粗骨料分布時(shí)所需平面面積含量,采用ANSYS/LS-DYNA自帶APDL語(yǔ)言編輯二級(jí)配圓形粗骨料任意分布面積控制程序,通過(guò)控制粗骨料投放平面面積含量,進(jìn)行粗骨料隨機(jī)投放。(2)根據(jù)粗骨料隨機(jī)投放程序,進(jìn)行了粗骨料體積含量、粗骨料最大顆粒直徑和粗骨料中間顆粒直徑不同二級(jí)配混凝土動(dòng)態(tài)破壞過(guò)程的數(shù)值模擬,提取相應(yīng)的應(yīng)力-應(yīng)變曲線(xiàn),并對(duì)模擬結(jié)果進(jìn)行了分析。數(shù)值模擬表明:①隨著粗骨料體積含量逐漸增大,二級(jí)配混凝土峰值應(yīng)力在粗骨料體積含量40%時(shí)最大;②二級(jí)配混凝土峰值應(yīng)力隨粗骨料最大顆粒直徑增大而減小;③隨著粗骨料中間顆粒直徑增大,二級(jí)配混凝土峰值應(yīng)力在粗骨料中間顆粒直徑20mm時(shí)為最大;④混凝土峰值應(yīng)力隨模型尺寸變化表現(xiàn)出明顯尺寸效應(yīng);⑤沖擊速度低,沖擊產(chǎn)生的能量低,宏觀(guān)裂紋較少;沖擊速度高,沖擊產(chǎn)生的能量高,宏觀(guān)裂紋多,碎塊較小,數(shù)量多。
[Abstract]:Concrete is one of the most common materials used in civil, industrial, safety protection and other buildings. It has high compressive strength, simple process and good corrosion resistance. In the application stage of concrete structure, not only slow change quasi static load should be considered, but also dynamic load such as impact and explosion resistance should be considered, so it is necessary to study the dynamic characteristics of concrete. Concrete is an isotropic material, but from a microscopic point of view, it is a composite composed of coarse aggregate and cement mortar. In this paper, the dynamic mechanical properties of two model size secondary concrete are analyzed by using ANSYS/LS-DYNA software. The concrete research contents are as follows: 1) using the Fuller gradation curve and the Vallavan plane transformation formula, the three-dimensional space problem is transformed into a two-dimensional plane problem. That is to say, the plane area content needed for coarse aggregate distribution is calculated by using the Vallavan plane transformation formula, and the area control program for arbitrary distribution of secondary circular coarse aggregate is edited by ANSYS/LS-DYNA with APDL language, and the content of coarse aggregate in plane area is controlled. The dynamic failure process of coarse aggregate volume content, maximum particle diameter of coarse aggregate and intermediate diameter of coarse aggregate were simulated according to the procedure of coarse aggregate random dropping. The corresponding stress-strain curves were extracted and the simulation results were analyzed. When the volume content of coarse aggregate is 40, the peak stress of secondary concrete increases with the diameter of coarse aggregate and decreases with the increase of diameter of coarse aggregate. The peak stress of secondary concrete is maximum when the diameter of coarse aggregate is 20mm. The change of peak stress with model size shows obvious size effect, such as low impact velocity, low energy produced by impact and less macroscopic crack. The impact velocity is high, the energy produced by the impact is high, the macroscopic crack is many, the fragment is small, the quantity is many.
【學(xué)位授予單位】：寧夏大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類(lèi)號(hào)】：TU528

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