本文選題：2024鋁合金 + 噴丸強化�。� 參考：《山東大學》2017年碩士論文

【摘要】：噴丸作為一種表面強化工藝,可有效提升材料的抗疲勞性能。通常認為疲勞性能的強化是由于噴丸引入的殘余應力,但噴丸在引入殘余應力的同時還會改變材料表面形貌而增加粗糙度,這對材料的疲勞性能存在負面影響,而粗糙度與殘余應力存在著一定的相關性。因此,噴丸所引入的殘余應力,所增加的粗糙度,兩者的相關性以及對疲勞壽命的影響都需要得到足夠關注。本文針對2024鋁合金,結(jié)合實驗研究與數(shù)值仿真研究各自的優(yōu)點,開展噴丸及相關實驗研究,然后建立相應的ABAQUS有限元數(shù)值模型來模擬實驗過程,通過實驗與仿真結(jié)果的對照,在驗證數(shù)值模型的正確性和有效性后,利用數(shù)值仿真進行參數(shù)影響的研究,主要研究內(nèi)容如下:(1)對2024鋁合金試件進行噴丸處理,實驗測量噴丸后的粗糙度特征值Ra,通過ABAQUS/Explicit建立多丸粒數(shù)值模型模擬噴丸過程,基于所提出的Ra離散化計算式,通過對節(jié)點位移進行統(tǒng)計分析得到Ra模擬值,通過實驗與模擬結(jié)果的對照,驗證仿真方法的正確性及有效性,最后利用該數(shù)值模型進行噴丸參數(shù)對粗糙度影響的研究。(2)對噴丸處理后的試件進行剝層殘余應力測量,得到噴丸殘余應力沿深度分布的曲線,同時通過多丸粒數(shù)值模型得到相應的仿真殘余應力曲線,通過兩者結(jié)果的比較研究來檢驗仿真方法,通過數(shù)值模型進行噴丸參數(shù)對殘余應力的影響研究。最后將不同參數(shù)下粗糙度與殘余應力的結(jié)果進行線性擬合及相關性分析,建立噴丸殘余應力特征值與相應粗糙度的相關關系。(3)利用2024鋁合金的三彎試樣,通過疲勞試驗機分別對噴丸與未噴丸的試件進行三彎疲勞實驗,得出噴丸對疲勞壽命影響的實驗結(jié)果。通過ABAQUS建立試件的二維平面應力模型,利用擴展有限元法模擬循環(huán)載荷下裂紋的萌生與擴展,對比實驗結(jié)果驗證該擴展有限元數(shù)值模型的正確性。最后利用該模型研究不同載荷工況下殘余應力對疲勞壽命的影響效果。
[Abstract]:As a surface strengthening process, shot peening can effectively improve the fatigue resistance of the material. It is generally believed that the strengthening of the fatigue properties is due to the residual stress introduced by the shot peening, but the surface morphology of the material will be changed and the roughness is increased while the residual stress is introduced, which has a negative effect on the fatigue property of the material, and the roughness and residual strength. The residual stress has a certain correlation. Therefore, the residual stress introduced by the shot peening, the increased roughness, the correlation between the two and the fatigue life need to be paid enough attention. In this paper, 2024 aluminum alloy, combining the advantages of experimental and numerical simulation research and numerical simulation, to carry out the shot peening and related experimental research, and then build up. The corresponding ABAQUS finite element numerical model is established to simulate the experimental process. The main research contents are as follows: (1) the shot peening treatment of 2024 aluminum alloy specimens is carried out, and the roughness of the shot peening is measured by the experiment. The eigenvalue Ra is used to simulate the shot peening process by the multi pellet numerical model of ABAQUS/Explicit. Based on the proposed Ra discrete calculation formula, the Ra simulation value is obtained by statistical analysis of the node displacements. The correctness and effectiveness of the simulation method are verified by the comparison between the experiment and the simulation results. Finally, the shot blasting parameters are carried out by the numerical model. Study on the influence of roughness. (2) measure the residual stress of the peeling layer after shot peening, get the curve of the residual stress along the depth distribution, and get the corresponding simulation residual stress curve through the multi pellet numerical model, and test the simulation method through the comparison study of the two results, and carry out the shot peening parameter through the numerical model. The effect of number on residual stress is studied. Finally, the results of roughness and residual stress under different parameters are linear fitting and correlation analysis, and the correlation between the characteristic values of residual stress of shot peening and the corresponding roughness is established. (3) using three bending specimens of 2024 aluminum alloy, the specimens of shot peening and unpeening are three respectively through fatigue testing machine. The experimental results of the effect of shot peening on fatigue life are obtained. A two-dimensional plane stress model of the specimen is established by ABAQUS. The propagation of crack initiation and propagation under cyclic loading is simulated by the extended finite element method, and the correctness of the extended finite element model is verified by comparison with the experimental results. Finally, the model is used to study the different load conditions. The effect of the residual stress on the fatigue life.
【學位授予單位】：山東大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TG146.21;TG668

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