激光噴丸強(qiáng)化鎳基合金的疲勞性能研究

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摘 要
本文以實(shí)現(xiàn)激光沖擊強(qiáng)化In718鎳基高溫合金工藝參數(shù)的優(yōu)化，提高In718鎳基合金的疲勞性能為研究目的，在深入分析國(guó)內(nèi)外關(guān)于激光沖擊強(qiáng)化技術(shù)和鎳基高溫合金疲勞性能的研究成果的基礎(chǔ)上，對(duì)不同激光能量和不同基體溫度下，In718鎳基高溫合金激光沖擊強(qiáng)化的殘余應(yīng)力場(chǎng)分布進(jìn)行了數(shù)值模擬，選取典型板狀光滑疲勞拉伸試樣、含預(yù)制小孔疲勞拉伸試樣以及激光沖擊強(qiáng)化后含預(yù)制殘余應(yīng)力場(chǎng)的疲勞試樣的疲勞性能進(jìn)行數(shù)值模擬研究，在此基礎(chǔ)上，實(shí)現(xiàn)激光沖擊強(qiáng)化過(guò)程工藝參數(shù)的優(yōu)化和疲勞服役壽命的預(yù)測(cè)。
通過(guò)COMSOL Multiphysics軟件建立有限元模型，分析了激光沖擊強(qiáng)化過(guò)程中試樣的殘余應(yīng)力場(chǎng)分布狀況和規(guī)律，并且研究脈沖激光能量和溫度因素對(duì)In718鎳基高溫合金激光沖擊強(qiáng)化誘導(dǎo)的動(dòng)態(tài)應(yīng)力場(chǎng)和穩(wěn)態(tài)應(yīng)力場(chǎng)的影響規(guī)律。利用COMSOL Multiphysics軟件模擬分析板狀光滑疲勞拉伸試樣、含預(yù)制小孔疲勞拉伸試樣以及激光沖擊強(qiáng)化后含預(yù)制殘余應(yīng)力場(chǎng)的疲勞試樣的應(yīng)力集中區(qū)域及特點(diǎn)，在此基礎(chǔ)上，實(shí)現(xiàn)激光沖擊強(qiáng)化對(duì)不同類(lèi)型In718鎳基高溫合金試樣疲勞性能的預(yù)測(cè)，結(jié)果表明：
（1）隨著激光能量的提高，試樣殘余壓應(yīng)力幅值增大，殘余壓應(yīng)力影響深度增加；隨著試樣溫度的提高，試樣殘余壓應(yīng)力幅值有所降低；
（2）板狀光滑疲勞拉伸試樣應(yīng)力集中部位在夾持區(qū)與拉伸區(qū)的過(guò)渡區(qū)域，含預(yù)制小孔疲勞拉伸試樣的主要應(yīng)力集中部位轉(zhuǎn)移到小孔處，含預(yù)制小孔疲勞拉伸試樣的疲勞壽命與板狀光滑疲勞拉伸試樣相比大幅下降；
（3）由于殘余壓應(yīng)力可以部分抵消外加拉伸載荷的作用，降低疲勞試樣中實(shí)際施加載荷的大小。在加載初期，雖然殘余壓應(yīng)力場(chǎng)在外加循環(huán)載荷作用下有所釋放，但是仍可有效延緩疲勞損傷的積累。激光沖擊強(qiáng)化形成的殘余壓應(yīng)力場(chǎng)能夠有效提高鎳基高溫合金In718的疲勞壽命。

關(guān)鍵詞：激光沖擊強(qiáng)化、In718鎳基合金、殘余應(yīng)力場(chǎng)、疲勞性能、數(shù)值模擬



ABSTRACT
In order to improve the fatigue property of In718 Superalloy and to optimize the parameters of laser shock peening, a simulation of LSP on 718 superalloy and virtual fatigue testing of several FEA models were carried out based on the lucubrating of numerous researches done by scientists and researches all over the world.
Firstly, numerical simulation research of LSP on In718 Superalloy under different laser pulse energy and different temperatures are carried out in COMSOL Multiphysics. Then in the fatigue module of COMSOL Multiphysics, virtual fatigue testings of standard plate fatigue testing specimen, fatigue testing specimen with small hole and fatigue testing specimen with residual stress field are explored. The following phenomena and laws are discovered during the numerical simulation researches.
(1) As the pulse energy of LSP improves, the greatest value of the residual stress goes up and the the residual stress field goes deeper. However, as the substrate temperature improves, the greatest value of the residual stresses goes down.
(2) The stress concentration area of plate smooth fatigue tensile specimen is in the transition area of clamping area and tensile area. The stress concentration area of fatigue tensile samples containing preformed hole transfer to the hole. The fatigue life of fatigue tensile samples with small hole has fallen dramatically compared with standard plate fatigue testing specimen.
(3) The residual stress field formed by laser shock processing can effectively improve the fatigue life of In718 nickel-based superalloy. Since the residual stress can be partially offset by the effect of the applied tensile load,reducing the actual size of the fatigue loads applied to the sample.In the early stage of loading,although the residual compressive stress field has been released under the applied cyclic loading, but still effectively delay the accumulation of fatigue damage.

Key Words: Laser Shock Peening, IN 718 Superalloy, Residual Stress, Fatigue Property, Numerical Simulation


目 錄

第一章 緒論 1
1.1引言 1
1.2鎳基高溫合金表面強(qiáng)化工藝的研究現(xiàn)狀 2
1.3激光噴丸強(qiáng)化技術(shù) 4
1.3.1激光噴丸強(qiáng)化技術(shù)研究現(xiàn)狀 5
1.3.2激光噴丸強(qiáng)化數(shù)值模擬技術(shù) 7
1.4 本文研究的意義及主要內(nèi)容 9
1.4.1本文研究的意義 9
1.4.2本文研究的主要內(nèi)容 9
第二章 激光噴丸強(qiáng)化鎳基合金殘余應(yīng)力場(chǎng)的數(shù)值模擬 11
2.1 激光沖擊強(qiáng)化工藝常用的仿真軟件 12
2.1.1 ANSYS\LS-DYNA & ANSYS 13
2.1.2 ABAQUS 14
2.1.3 COMSOL Multiphysics 15
2.2 數(shù)值仿真的基本方法 15
2.3 材料動(dòng)態(tài)本構(gòu)模型 16
2.4 沖擊波的傳播規(guī)律和加載方法 17
2.5 不同激光沖擊參數(shù)下激光噴丸強(qiáng)化仿真 19
2.5.1不同激光能量 19
2.5.2不同溫度 21
2.6 本章小結(jié) 22
第三章 激光噴丸強(qiáng)化鎳基合金疲勞性能的數(shù)值模擬 24
3.1 疲勞分析基本方法 24
3.1.1疲勞的概念 24
3.1.2疲勞分析流程 24
3.1.3疲勞分析的荷載譜模式 25
3.2 疲勞分析軟件 26
3.2.1 MSC.Fatigue 27
3.2.2 COMSOL Fatigue Module 28
3.3 疲勞分析的數(shù)值模擬 28
3.3.1 疲勞仿真試樣分析 28
3.3.2 基于載荷譜模式的疲勞分析 35
3.4 本章小結(jié) 36
第四章 激光沖擊強(qiáng)化實(shí)驗(yàn)平臺(tái) 37
4.1 激光沖擊強(qiáng)化實(shí)驗(yàn)平臺(tái)的組成 37
4.2 運(yùn)動(dòng)控制平臺(tái)的結(jié)構(gòu)方案 37
4.3 運(yùn)動(dòng)控制平臺(tái)的軟件 40
4.4 本章小結(jié) 40
第五章 總結(jié)與展望 41
5.1 總結(jié) 41
5.1 展望 41
參考文獻(xiàn)： 42
致謝 45