發(fā)布時(shí)間：2019-04-20 16:08

【摘要】：激光沖擊強(qiáng)化是一種新型的表面強(qiáng)化技術(shù),它使用高能量和短脈沖的激光束作為工具,對(duì)材料表面進(jìn)行強(qiáng)化處理。本文運(yùn)用數(shù)值模擬與實(shí)驗(yàn)相結(jié)合的研究方法,研究激光沖擊鋁合金圓桿件后,材料中殘余應(yīng)力的分布情況及其對(duì)材料疲勞壽命的影響,主要內(nèi)容如下:首先,在激光沖擊波產(chǎn)生原理和氣體動(dòng)力學(xué)理論的基礎(chǔ)上,對(duì)激光沖擊波誘導(dǎo)的峰值壓力在無約束和有約束模型中的傳播過程進(jìn)行比較研究。根據(jù)爆轟波的C-J理論,闡述了激光誘導(dǎo)的應(yīng)力場形成原理,討論了沖擊波在約束模型下的傳播機(jī)理,建立了激光沖擊強(qiáng)化金屬材料的力學(xué)模型,對(duì)激光誘導(dǎo)產(chǎn)生的峰值壓力進(jìn)行了公式的推導(dǎo)和估算。其次,使用ABAQUS數(shù)值模擬軟件建立鋁合金圓桿的有限元模型,來模擬激光沖擊鋁合金圓柱桿后,桿內(nèi)應(yīng)力波的傳播與衰減過程,并分別分析了激光單點(diǎn)和多點(diǎn)沖擊后,圓柱桿端面和圓周面的殘余應(yīng)力分布情況,研究了圓桿直徑因素對(duì)殘余應(yīng)力分布規(guī)律的影響。通過比較激光沖擊在曲面上殘余應(yīng)力分布規(guī)律的差異,探究了激光沖擊強(qiáng)化在曲面上殘余應(yīng)力的分布特點(diǎn)。最后,以2024鋁合金圓桿件為材料進(jìn)行激光沖擊強(qiáng)化實(shí)驗(yàn)。對(duì)強(qiáng)化后和未強(qiáng)化的試樣進(jìn)行疲勞試驗(yàn)。對(duì)比分析激光沖擊強(qiáng)化對(duì)圓桿件疲勞壽命的影響。而且,通過掃描電子顯微鏡對(duì)試樣疲勞斷口的微觀形貌特征進(jìn)行了觀測,從微觀角度解釋了激光沖擊強(qiáng)化鋁合金圓桿件的延壽機(jī)理。
[Abstract]:Laser shock hardening is a new surface strengthening technology, which uses high energy and short pulse laser beam as a tool to strengthen the surface of materials. In this paper, the distribution of residual stress and its influence on fatigue life of aluminum alloy rod after laser shock are studied by means of numerical simulation and experiment. The main contents are as follows: first of all, the distribution of the residual stress in the material and its influence on the fatigue life of the material are studied. Based on the generation principle of laser shock wave and the theory of gas dynamics, the propagation process of peak pressure induced by laser shock wave in unconstrained and constrained models is compared. The formation principle of laser-induced stress field and the propagation mechanism of shock wave under the constraint model are discussed. The mechanical model of laser shock hardening metal material is established according to the theory of C ~ (? J) of detonation wave, and the mechanism of laser-induced stress field formation is discussed in this paper. The formula of peak pressure induced by laser is derived and estimated. Secondly, the finite element model of aluminum alloy circular rod is established by using ABAQUS numerical simulation software to simulate the propagation and attenuation of stress wave in aluminum alloy cylindrical rod after laser shock, and the single-point and multi-point laser shock are analyzed respectively. The distribution of residual stress at the end and circumference of cylindrical rod is studied. The influence of diameter factor on the distribution of residual stress is studied. By comparing the difference of the residual stress distribution on the surface of laser shock, the distribution characteristics of the residual stress on the surface strengthened by laser shock are discussed. Finally, the laser shock strengthening experiment of 2024 aluminum alloy circular bar was carried out. Fatigue tests were carried out on the strengthened and unstrengthened specimens. The influence of laser shock strengthening on the fatigue life of circular member is analyzed. In addition, the micro-morphology of fatigue fracture was observed by scanning electron microscope, and the mechanism of prolonging the life of aluminum alloy round bar strengthened by laser shock was explained from the micro-point of view.
【學(xué)位授予單位】：安徽工業(yè)大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TG665

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