發(fā)布時(shí)間：2018-05-17 07:07

  本文選題：動(dòng)態(tài)沖擊 + 動(dòng)態(tài)特性��； 參考：《湖南科技大學(xué)》2015年碩士論文

【摘要】：含沙流導(dǎo)致的過流件沖蝕是水電工程中存在的主要技術(shù)問題,研究表明它是粒子流對(duì)材料表面連續(xù)沖擊損傷的結(jié)果。上世紀(jì)80年代,研究人員開始進(jìn)行聚合物材料抗沖蝕的應(yīng)用試驗(yàn),結(jié)果表明,在中低水頭的高含沙環(huán)境中,以超高分子量聚乙烯(UHMWPE)為代表的聚合物基復(fù)合材料顯示出比普通碳鋼材料更優(yōu)良的抗沖蝕性能。根據(jù)接觸動(dòng)力學(xué)理論,材料的動(dòng)態(tài)力學(xué)特性對(duì)材料沖擊破壞有著重要影響,隨著聚合物復(fù)合材料在沖蝕環(huán)境中的推廣應(yīng)用,開展聚合物復(fù)合材料動(dòng)態(tài)沖擊特性的研究,對(duì)于揭示聚合物材料沖蝕損傷機(jī)理,完善抗沖蝕聚合物復(fù)合材料的組分設(shè)計(jì),改進(jìn)抗沖蝕聚合物復(fù)合材料制備方法,進(jìn)一步提高其抗沖蝕綜合性能有著重要的科學(xué)與應(yīng)用意義。本文選擇兩種材料的填充粒子,采用壓制燒結(jié)工藝制備了UHMWPE復(fù)合材料,應(yīng)用霍普金森壓桿實(shí)驗(yàn)技術(shù)研究了復(fù)合材料的動(dòng)態(tài)沖擊性能,并通過數(shù)據(jù)處理分析了材料在沖擊過程中的吸能特性;通過沖蝕磨損實(shí)驗(yàn)考察了復(fù)合材料的抗粒子流沖擊損傷(沖蝕)性能;結(jié)合實(shí)驗(yàn)結(jié)果分析討論了材料損傷與本身靜、動(dòng)態(tài)特性及材料微觀結(jié)構(gòu)的相關(guān)性,主要結(jié)論如下:1.填充粒子可提高UHMWPE復(fù)合材料的表面硬度、屈服應(yīng)力,但填充粒子后的復(fù)合材料比純UHMWPE的沖擊韌性降低。相同填充量時(shí),云母/UHMWPE復(fù)合材料的沖擊韌性值高于碳酸鈣/UHMWPE復(fù)合材料。2.填充粒子能有效提高UHMWPE復(fù)合材料的動(dòng)態(tài)屈服應(yīng)力值,在相同應(yīng)變率下,UHMWPE復(fù)合材料的動(dòng)態(tài)屈服應(yīng)力值隨粒子填充量的加大而提高,且填充碳酸鈣粒子比云母粒子更明顯。UHMWPE復(fù)合材料的動(dòng)態(tài)屈服應(yīng)力隨應(yīng)變率的增大而提高,具有顯著的應(yīng)變率強(qiáng)化效應(yīng)。3.根據(jù)動(dòng)態(tài)實(shí)驗(yàn)數(shù)據(jù),采用吸能效率評(píng)價(jià)了UHMWPE復(fù)合材料的動(dòng)態(tài)吸能特性,結(jié)果表明,在應(yīng)變率3200/s以下范圍內(nèi),UHMWPE復(fù)合材料的吸能效率隨應(yīng)變率的增加而提高。粒子填充量在5%~15%范圍內(nèi),復(fù)合材料吸能效率相對(duì)UHMWPE提高15%左右。填充量相同時(shí),填充云母粒子比碳酸鈣粒子更能提高UHMWPE復(fù)合材料的吸能效率,相差在8%左右。4.沖蝕實(shí)驗(yàn)表明,UHMWPE復(fù)合材料具有優(yōu)良的抗沖蝕性能,相同工況下,UHMWPE復(fù)合材料的沖蝕磨損量僅為45#鋼的0.08倍。5%云母填充量的UHMWPE復(fù)合材料的抗沖蝕性能比純UHMWPE高10%左右。5.UHMWPE復(fù)合材料的抗沖蝕性能與其硬度、靜態(tài)屈服應(yīng)力等靜態(tài)性能相關(guān)性不高,而與其沖擊韌性和動(dòng)態(tài)屈服應(yīng)力乘積、吸能效率等動(dòng)態(tài)性能有良好的正對(duì)應(yīng)關(guān)系。UHMWPE復(fù)合材料優(yōu)良的抗沖擊損傷性能從能量角度可解釋為聚合物內(nèi)部分子鏈的伸縮與球晶結(jié)構(gòu)的扭轉(zhuǎn)有效耗散了沖擊能量;填充粒子減少微剪切帶的形成,起到增強(qiáng)作用。
[Abstract]:The main technical problem in hydropower engineering is the erosion of overflowing parts caused by sand flow. The research shows that it is the result of continuous impact damage caused by particle flow on the surface of materials. In the 1980s, researchers began to test the erosion resistance of polymer materials, and the results showed that in high-sand environments with low and low water head, The polymer matrix composites, represented by UHMWPE, show better erosion resistance than ordinary carbon steel materials. According to the contact dynamics theory, the dynamic mechanical properties of the materials have an important effect on the impact failure of the materials. With the popularization and application of polymer composites in the erosion environment, the dynamic impact characteristics of polymer composites are studied. It is of great scientific and practical significance to reveal the erosion damage mechanism of polymer materials, improve the composition design of erosion-resistant polymer composites, improve the preparation method of anti-erosion polymer composites, and further improve their comprehensive anti-erosion properties. In this paper, UHMWPE composites were prepared by pressing sintering process, and the dynamic impact properties of the composites were studied by using Hopkinson compression bar test technique. The energy absorption characteristics of the materials during impact are analyzed by data processing, the impact damage (erosion) properties of the composites are investigated by erosion wear experiments, and the damage and static properties of the composites are discussed by combining the experimental results. The main conclusions are as follows: 1. The surface hardness and yield stress of UHMWPE composites can be improved by filling particles, but the impact toughness of the composites filled with particles is lower than that of pure UHMWPE. The impact toughness of mica / UHMWPE composite is higher than that of calcium carbonate / UHMWPE composite. The dynamic yield stress of UHMWPE composites can be improved by filling particles, and the dynamic yield stress of UHMWPE composites increases with the increase of particle filling at the same strain rate. The dynamic yield stress of UHMWPE composites increases with the increase of strain rate, and it has a significant strain rate strengthening effect .3.The results show that the dynamic yield stress of UHMWPE composites is more obvious than that of mica particles, and the dynamic yield stress increases with the increase of strain rate. According to the dynamic experimental data, the dynamic energy absorption characteristics of UHMWPE composites are evaluated by energy absorption efficiency. The results show that the energy absorption efficiency of UHMWPE composites increases with the increase of strain rate in the range of 3 200 / s. The energy absorption efficiency of the composite is about 15% higher than that of UHMWPE in the range of 5% particle filling. When the filling amount is the same, filling mica particles can improve the energy absorption efficiency of UHMWPE composites better than calcium carbonate particles, and the difference is about 8%. 4. The erosion test shows that the UHMWPE composite has excellent erosion resistance. Under the same condition, the erosion resistance and hardness of the UHMWPE composite with only 0.08 times the amount of mica filled with 4 steel is about 10% higher than that of the pure UHMWPE under the same condition. 5. The erosion resistance and hardness of the UHMWPE composite is about 10% higher than that of the pure UHMWPE composite, and the erosion resistance of the UHMWPE composite is only 0.08% of that of the pure UHMWPE composite. The static properties, such as static yield stress, are not highly correlated with their impact toughness and dynamic yield stress. The excellent impact damage resistance of UHMWPE composites can be explained from the energy point of view as the molecular chain stretching inside the polymer and the torsion of spherulite structure effectively dissipating the impact energy. Filling particles reduce the formation of microshear bands and play an enhanced role.
【學(xué)位授予單位】：湖南科技大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TB33

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本文編號(hào)：1900422