激光冲击强化对AA2024-T351铝合金残余应力分布和疲劳寿命的影响研究
发布时间：2022-11-12 09:08
众所周知,零部件在循环疲劳载荷作用下,其疲劳失效通常起始于最表层应力集中位置的裂纹区域。通过喷丸强化和激光冲击强化等技术将残余应力引入材料的表层可以延缓疲劳裂纹萌生和扩展,从而提高部件的疲劳寿命以及抗磨损和应力腐蚀开裂（SCC）性能。激光冲击过程中,由等离子冲击破产生的塑性变形可以在材料表面诱导产生残余应力。由于AA2024-T351铝合金在航空航天工业领域中重要作用,研究残余应力对该材料疲劳性能的影响,从而达到抑制疲劳失效,提高疲劳寿命的目的是有必要的。因此,本文的研究题目是激光冲击强化（LSP）对AA2024-T351铝合金残余应力分布和疲劳寿命的影响,创新性的提出了一种梯度式的扫描策略来优化激光喷丸过程中脉冲扫描路径。采用三维有限元分析（FEA）法模拟残余应力分布,并建立模拟和实验结果的关系。利用优化的有限元模型预测了激光冲击过程中,梯度式扫描策略和常规扫描策略对残余应力分布的影响,并通过实验进行了验证。利用两种扫描策略在“骨棒”试样上进行激光冲击强化实验,并将两种激光冲击试样的疲劳寿命与未冲击试样进行对比,结果表明激光冲击强化可以提高材料的疲劳寿命。与未冲击试样相比,策略1试样...
【文章页数】：148 页
【学位级别】：博士
【文章目录】：
ABSTRACT
摘要
DEDICATION
CHAPTER 1 INTRODUCTION AND LITERATURE REVIEW
1.1 Introduction
1.2 Literature Review
1.2.1 Severe plastic deformation(SPD)methods
1.2.2 Laser shock peening and its processing parameters on metals materials
1.3 Literature Summary
1.4 Research Objectives
1.5 Dissertation Outline
CHAPTER 2 EXPERIMENTAL MATERIAL AND METHODS
2.1 Properties of Aluminum alloys(AA)
2.2 Material Preparation
2.3 Laser Shock Peening(LSP)
2.4 Microhardness and specimen preparation
2.4.1 Microhardness measurement
2.4.2 Microhardness specimen preparation
2.4.3 Scanning electron microscope(SEM)
2.4.4 SEM specimen preparation
2.4.5 Optical microscope(OM)
2.5 Surface roughness and topography
2.6 X-ray diffraction analysis
2.7 Residual measurement
2.8 Transmission electron microscope(TEM)
2.9 Fatigue Test
2.10 Tensile test
2.11 LSP and simulation
2.12 Modelling pressure loading and plastic deformation due to shockwaves
2.13 Thin and thick geometry
2.14 Material simulation model
2.15 LSP and its processing parameters on AA2024-T351 aluminum alloy
CHAPTER 3 THE EFFECTS OF SCANNING PATH GRADIENT ON THE COMPRESSIVE RESIDUAL STRESS DISTRIBUTION AND FATIGUE LIFE BY LSP
3.1 Introduction
3.2 FE simulation and compressive residual stress distribution
3.2.1 Strategy1:Scanning path gradient parallel to fatigue load
3.2.2 Strategy2:Scanning path in advancing direction to fatigue load
3.3 Results and discussion
3.4 Residual stress distribution comparative to experimental and simulated results
3.4.1 Strategy 1
3.4.2 Strategy 2
3.5 Fatigue life improvement
3.6 Fatigue fracture
3.7 SUMMARY
CHAPTER 4 THE EFFECTS OF LASER ENERGY ON FATIGUE BEHAVIOR INDUCED BY LASER SHOCK PEENED(LSP)ON AA2024-T351 ALUMINUM ALLOY
4.1 Introduction
4.2 Experimental details
4.3 Results and discussion
4.3.1 Effect of pulse energy on residual stress
4.3.2 Effect pulse energy on microhardness
4.4 Fatigue fracture analysis
4.5 Fatigue crack behavior and microstructure on the fractured surfaces
4.6 Fatigue life
4.7 SUMMARY
CHAPTER 5 THE EFFECTS OF MULTIPLE PEENING ON FATIGUE LIFE AND SURFACE INTEGRITY ON AA2024-T351 ALUMINUM ALLOY WITH LSP
5.1 Introduction
5.2 Experimental materials and methods
5.3 Results and discussion
5.3.1 Tensile properties
5.3.2 Fracture analysis
5.3.3 TEM observation
5.4 Effects of multiple LSP impacts on mechanical properties
5.4.1 XRD diffraction and phase analysis
5.4.2 Residual stress distribution
5.4.3 Microhardness analysis
5.4.4 Surface roughness analysis
5.5 Fatigue life and fracture surfaces
5.5.1 Fatigue life
5.5.2 Fatigue fracture
5.6 SUMMARY
CHAPTER 6 CONCLUSIONS AND RECOMMENDATION
6.1 CONCLUSIONS
6.1.1 The effects of scanning path gradient direction on residual stress distribution and fatigue life induced by LSP
6.1.2 The effects of different laser energy of fatigue behavior and residual stress distribution induced by LSP
6.1.3 The effects of multiple peening on fatigue life and surface integrity on AA2024-T351 aluminum alloy with LSP
6.2 NOVELTY CONTRIBUTION
6.3 FUTURE RESEARCH WORK
REFERENCES
ACKNOWLEDGEMENT
PUBLICATIONS
【参考文献】：
期刊论文
[1]Numerical simulation of residual stress field induced by laser shock processing with square spot[J]. 曹子文,车志刚,邹世坤,费群星. Journal of Shanghai University（English Edition）. 2011(06)
[2]约束层对激光驱动冲击波压力影响机理的理论研究[J]. 顾永玉,张永康,张兴权,史建国. 物理学报. 2006(11)
[3]激光冲击处理降低铝合金裂纹扩展速率的研究[J]. 邹世坤 ,王健 ,王华明 ,韩海军 ,王春生. 航空制造技术. 2002(09)
本文编号：3706091
【文章页数】：148 页
【学位级别】：博士
【文章目录】：
ABSTRACT
摘要
DEDICATION
CHAPTER 1 INTRODUCTION AND LITERATURE REVIEW
1.1 Introduction
1.2 Literature Review
1.2.1 Severe plastic deformation(SPD)methods
1.2.2 Laser shock peening and its processing parameters on metals materials
1.3 Literature Summary
1.4 Research Objectives
1.5 Dissertation Outline
CHAPTER 2 EXPERIMENTAL MATERIAL AND METHODS
2.1 Properties of Aluminum alloys(AA)
2.2 Material Preparation
2.3 Laser Shock Peening(LSP)
2.4 Microhardness and specimen preparation
2.4.1 Microhardness measurement
2.4.2 Microhardness specimen preparation
2.4.3 Scanning electron microscope(SEM)
2.4.4 SEM specimen preparation
2.4.5 Optical microscope(OM)
2.5 Surface roughness and topography
2.6 X-ray diffraction analysis
2.7 Residual measurement
2.8 Transmission electron microscope(TEM)
2.9 Fatigue Test
2.10 Tensile test
2.11 LSP and simulation
2.12 Modelling pressure loading and plastic deformation due to shockwaves
2.13 Thin and thick geometry
2.14 Material simulation model
2.15 LSP and its processing parameters on AA2024-T351 aluminum alloy
CHAPTER 3 THE EFFECTS OF SCANNING PATH GRADIENT ON THE COMPRESSIVE RESIDUAL STRESS DISTRIBUTION AND FATIGUE LIFE BY LSP
3.1 Introduction
3.2 FE simulation and compressive residual stress distribution
3.2.1 Strategy1:Scanning path gradient parallel to fatigue load
3.2.2 Strategy2:Scanning path in advancing direction to fatigue load
3.3 Results and discussion
3.4 Residual stress distribution comparative to experimental and simulated results
3.4.1 Strategy 1
3.4.2 Strategy 2
3.5 Fatigue life improvement
3.6 Fatigue fracture
3.7 SUMMARY
CHAPTER 4 THE EFFECTS OF LASER ENERGY ON FATIGUE BEHAVIOR INDUCED BY LASER SHOCK PEENED(LSP)ON AA2024-T351 ALUMINUM ALLOY
4.1 Introduction
4.2 Experimental details
4.3 Results and discussion
4.3.1 Effect of pulse energy on residual stress
4.3.2 Effect pulse energy on microhardness
4.4 Fatigue fracture analysis
4.5 Fatigue crack behavior and microstructure on the fractured surfaces
4.6 Fatigue life
4.7 SUMMARY
CHAPTER 5 THE EFFECTS OF MULTIPLE PEENING ON FATIGUE LIFE AND SURFACE INTEGRITY ON AA2024-T351 ALUMINUM ALLOY WITH LSP
5.1 Introduction
5.2 Experimental materials and methods
5.3 Results and discussion
5.3.1 Tensile properties
5.3.2 Fracture analysis
5.3.3 TEM observation
5.4 Effects of multiple LSP impacts on mechanical properties
5.4.1 XRD diffraction and phase analysis
5.4.2 Residual stress distribution
5.4.3 Microhardness analysis
5.4.4 Surface roughness analysis
5.5 Fatigue life and fracture surfaces
5.5.1 Fatigue life
5.5.2 Fatigue fracture
5.6 SUMMARY
CHAPTER 6 CONCLUSIONS AND RECOMMENDATION
6.1 CONCLUSIONS
6.1.1 The effects of scanning path gradient direction on residual stress distribution and fatigue life induced by LSP
6.1.2 The effects of different laser energy of fatigue behavior and residual stress distribution induced by LSP
6.1.3 The effects of multiple peening on fatigue life and surface integrity on AA2024-T351 aluminum alloy with LSP
6.2 NOVELTY CONTRIBUTION
6.3 FUTURE RESEARCH WORK
REFERENCES
ACKNOWLEDGEMENT
PUBLICATIONS
【参考文献】：
期刊论文
[1]Numerical simulation of residual stress field induced by laser shock processing with square spot[J]. 曹子文,车志刚,邹世坤,费群星. Journal of Shanghai University（English Edition）. 2011(06)
[2]约束层对激光驱动冲击波压力影响机理的理论研究[J]. 顾永玉,张永康,张兴权,史建国. 物理学报. 2006(11)
[3]激光冲击处理降低铝合金裂纹扩展速率的研究[J]. 邹世坤 ,王健 ,王华明 ,韩海军 ,王春生. 航空制造技术. 2002(09)
本文编号：3706091
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